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2,800 | Acquired atrioventricular block in a patient with sinus node disease on single-chamber atrial pacing. | Single-chamber atrial pacing is the most physiological and yet economical modality of treatment in patients with symptomatic sinus node disease with normal atrioventricular conduction. However, because of the possibility of future development of a high-degree atrioventricular block and atrial fibrillation, most patients are implanted either dual- or single-chamber right ventricular pacemakers. We report a patient with symptomatic sinus node disease on single-chamber atrial pacing for the past 7 years who developed a progressive increase in the PR interval and ultimately presented with symptomatic high-degree atrioventricular block requiring pacemaker upgradation. The pacemaker was upgraded to the single-chamber ventricular mode with one additional ventricular lead introduced from the same side percutaneously. |
2,801 | Desflurane improves neurologic outcome after low-flow cardiopulmonary bypass in newborn pigs. | Despite improvements in neonatal heart surgery, neurologic complications continue to occur from low-flow cardiopulmonary bypass (LF-CPB) and deep hypothermic circulatory arrest (DHCA). Desflurane confers neuroprotection against ischemia at normothermia and for DHCA. This study compared neurologic outcome of a desflurane-based with a fentanyl-based anesthetic for LF-CPB.</AbstractText>Thirty piglets aged 1 week received either fentanyl-droperidol (F/D), desflurane 4.5% (Des4.5), or desflurane 9% (Des9) during surgical preparation and CPB. Arterial blood gases, glucose, heart rate, arterial pressure, brain temperature, and cerebral blood flow (laser Doppler flowmetry) were recorded. After CPB cooling (22 degrees C brain) using pH-stat strategy, LF-CPB was performed for 150 min followed by CPB rewarming, separation from CPB, and extubation. On postoperative day 2, functional and histologic outcomes were assessed.</AbstractText>Cardiovascular variables were physiologically similar between groups before, during, and after LF-CPB. Cerebral blood flow during LF-CPB (13% of pre-CPB value) did not differ significantly between the groups. Functional disability was worse in F/D than in Des9 (P = 0.04) but not Des4.5 (P = 0.1). In neocortex, histopathologic damage was greater in F/D than in Des4.5 (P = 0.03) and Des9 (P = 0.009). In hippocampus, damage was worse in F/D than in Des9 (P = 0.01) but not Des4.5 (P = 0.08). The incidences of ventricular fibrillation during LF-CPB were 90, 60, and 10% for F/D, Des4.5 (P = 0.06), and Des9 (P = 0.0002), respectively.</AbstractText>Desflurane improved neurologic outcome following LF-CPB compared with F/D in piglets, indicated by less functional disability and less histologic damage, especially with Des9. Desflurane may have produced cardiac protection, suggested by a lower incidence of ventricular fibrillation.</AbstractText> |
2,802 | Transient proarrhythmic state following atrioventricular junction radiofrequency ablation: pathophysiologic mechanisms and recommendations for management. | The induction of complete heart block by radiofrequency ablation of the atrioventricular junction combined with pacemaker implantation has become an established therapy for rate control in patients with atrial fibrillation who are unresponsive to drugs. Reports of ventricular arrhythmias and sudden death after ablation have, however, raised concerns about safety. Ventricular arrhythmias are usually polymorphic and related to a phase of electrical instability due to an initial prolongation and then slow adaptation of repolarization caused by the change in heart rate and activation sequence. Structural heart disease, and other factors that predispose for the acquired long QT syndrome, seem to add to the risk. Ventricular activation and repolarization stabilize during the first week after the procedure. Routine pacing at 80 beats per minute during this phase is recommended, as well as in hospital monitoring for at least 48 hours. Patients with high-risk features for arrhythmias, such as congestive heart failure or impaired left ventricular function, may require pacing at higher rates. Adjustment of the pacing rate-although rarely below 70 beats per minute-is usually undertaken after a week in most patients, preferably after an electrocardiographic evaluation for repolarization abnormalities at the lower rate. |
2,803 | Effects of subclinical thyroid dysfunction on the heart. | Mounting evidence indicates that subclinical thyroid dysfunction has important clinical effects and prognostic implications, supporting the view that it is not a compensated biochemical change sensu strictu.</AbstractText>To review clinical information on the effects of subclinical thyroid dysfunction on the heart.</AbstractText>English-language articles identified from files and a MEDLINE search (1970-September 2001), references of relevant articles, textbooks, and meeting abstracts.</AbstractText>Reports on the effects of subclinical hypothyroidism and subclinical hyperthyroidism on the cardiovascular system in humans.</AbstractText>Data on cardiac structure and performance, arrhythmias, and risk for coronary artery disease were independently assessed by all authors and summarized.</AbstractText>Subclinical hypothyroidism is associated with impaired left ventricular diastolic function at rest, systolic dysfunction on effort, and enhanced risk for atherosclerosis and myocardial infarction. Subclinical hyperthyroidism is associated with increased heart rate, atrial arrhythmias, increased left ventricular mass with marginal concentric remodeling, impaired ventricular relaxation, reduced exercise performance, and increased risk for cardiovascular death. All abnormalities were reversed by restoration of euthyroidism (subclinical hypothyroidism) or were blunted by beta-blockade and tailoring of the l -thyroxine dose (subclinical hyperthyroidism).</AbstractText>The heart responds to the minimal but persistent changes in circulating thyroid hormone levels typical of subclinical thyroid dysfunction. Thus, the condition is not a compensated biochemical change sensu strictu, and timely treatment should be considered in an attempt to avoid adverse cardiovascular effects.</AbstractText> |
2,804 | Automated external defibrillation in cardiac surgery. | Revision open heart surgery may be impeded by a dense network of pericardial adhesions rendering cardiac mobilization laborious or incomplete, and internal defibrillation impossible. External defibrillation, the current alternative to internal defibrillation, may result in myocardial stunning secondary to the delivery of escalating, monophasic, high-energy shocks. Automated external defibrillation, by delivering consecutive, non-escalating, impedance-compensated, low-energy, biphasic electric shocks to the myocardium, may provide a more effective and safer option whilst reducing the risk of myocardial stunning. |
2,805 | Defibrillation with a minimally invasive direct cardiac massage device. | This study examined (1) the defibrillation efficacy of using a minimally invasive direct cardiac massage (MID-CM) device as one electrode of the defibrillation electrical circuit and (2) the effect on external defibrillation of defibrillating when the MID-CM device is in place and a pneumothorax is present.</AbstractText>Part 1: in seven pigs, defibrillation thresholds (DFTs) were determined with a truncated exponential biphasic waveform. DFTs were determined for five electrode configurations: standard transthoracic defibrillation with electrodes on the left and right chest walls (1), with the MID-CM as one of the defibrillation electrodes pressed gently (2) or firmly (3) against the heart with the right chest wall patch as the second electrode, the same as (1) with the MID-CM device in place and the lungs at end-inspiration (4) or at end-expiration (5). Part 2: in six pigs, DFTs were determined with a monophasic damped sinusoidal waveform with external defibrillation electrodes (1) and with the device as one defibrillation electrode and the other electrode on either the anterior (2), lateral (3), or posterior right chest wall (4).</AbstractText>Part 1: the DFTs for (2) or (3) were not different (18.7+/-12.4 vs. 17.0+/-8.3 J), but both DFTs were lower than that for (1) (155+/-45 J). The DFT was elevated for (4) (205+/-69 J) compared with (1). For (5) only one animal could be defibrillated with shocks up to 360 J. Part 2: the DFTs for (2), (3) or (4) were not different (19.5+/-11.0, 25.4+/-9.4, 27.4+/-9.0 J), but all three were lower than the DFT for (1) (198+/-70 J).</AbstractText>Using the MID-CM device as one electrode of the defibrillation circuit markedly lowers the DFT compared with that for standard transthoracic defibrillation for both a monophasic and biphasic waveform. Defibrillation with the device in place and the chest opened elevates the DFT for external defibrillation much more during end-expiration than during end-inspiration.</AbstractText> |
2,806 | Evaluation of LUCAS, a new device for automatic mechanical compression and active decompression resuscitation. | LUCAS is a new gas-driven CPR device providing automatic chest compression and active decompression. In an artificial thorax model, superior pressure and flow were obtained with LUCAS compared with manual CPR. In a randomized study on pigs with induced ventricular fibrillation significantly higher cardiac output, carotid artery blood flow, end-tidal CO(2), intrathoracic decompression-phase aortic- and coronary perfusion pressures were obtained with LUCAS-CPR (83% ROSC) compared to manual CPR (0% ROSC). In normothermic fibrillating pigs, the ROSC rate was 100% after 15 min and 38% after 60 min of LUCAS-CPR (no drug treatment). The ROSC rate increased to 75% if surface cooling to 34 degrees C was applied during the first 30 min of the 1-h resuscitation period. Experience with the first 20 patients has shown that LUCAS is light (6.5 kg), easy to handle, quick to apply (10-20 s), maintains a correct position, and works optimally during transport both on stretchers and in ambulances. In one hospital patient with a witnessed asystole where manual CPR failed, LUCAS-CPR achieved ROSC within 3 min. One year later the patient's mental capacity was fully intact. To conclude, LUCAS-CPR gives significantly better circulation during ventricular fibrillation than manual CPR. |
2,807 | Management of heart failure in primary care (the IMPROVEMENT of Heart Failure Programme): an international survey. | Heart failure is a prevalent condition that is generally treated in primary care. The aim of this study was to assess how primary-care physicians think that heart failure should be managed, how they implement their knowledge, and whether differences exist in practice between countries.</AbstractText>The survey was undertaken in 15 countries that had membership of the European Society of Cardiology (ESC) between Sept 1, 1999, and May 31, 2000. Primary-care physicians' knowledge and perceptions about the management of heart failure were assessed with a perception survey and how a representative sample of patients was managed with an actual practice survey.</AbstractText>1363 physicians provided data for 11062 patients, of whom 54% were older than 70 years and 45% were women. 82% of patients had had an echocardiogram but only 51% of these showed left ventricular systolic dysfunction. Ischaemic heart disease, hypertension, diabetes mellitus, atrial fibrillation, and major valve disease were all common. Physicians gave roughly equal priority to improvement of symptoms and prognosis. Most were aware of the benefits of ACE inhibitors and beta blockers. 60% of patients were prescribed ACE inhibitors, 34% beta blockers but only 20% received these drugs in combination. Doses given were about 50% of targets suggested in the ESC guidelines. If systolic dysfunction was documented, ACE inhibitors were more likely and beta blockers less likely to be prescribed than when there was no evidence of systolic dysfunction.</AbstractText>Results from this survey suggest that most patients with heart failure are appropriately investigated, although this finding might be as a result of high rates of hospital admissions. However, treatment seems to be less than optimum, and there are substantial variations in practice between countries. The inconsistencies between physicians' knowledge and the treatment that they deliver suggests that improved organisation of care for heart failure is required.</AbstractText> |
2,808 | Mitral valve surgery in patients with poor left ventricular function. | Mitral valve surgery for the correction of secondary mitral valve regurgitation (MR) in cardiomyopathy is associated with a poor outcome. Numerous studies have identified a severe left ventricular dysfunction as an indicator for a poor prognosis. The aim of the study was to asses the follow-up after mitral valve surgery and severe left ventricular dysfunction.</AbstractText>Between 1994 and 2000, 31 patients with mitral regurgitation and a left ventricular ejection fraction of below thirty percent undergoing isolated repair (n = 16) or replacement (n = 15) were investigated. All patients received maximal drug therapy. Twenty-one patients were New York Heart Association (NYHA) class III and 10 were class IV. Follow-up with echocardiography, ECG, and chest x-ray was performed in 87 % of the survivors. The mean duration of follow-up was 39 +/- 16 months.</AbstractText>The mean duration of ICU and hospital stay was 3.6 +/- 2.1 days and 8.1 +/- 5.4 days, respectively. The 1-, 2-, and 5-year survival rates were 91 %, 84 %, and 77 %, respectively. NYHA class improved from 3.3 +/- 0.8 to 2.1 +/- 0.7 at follow-up (p < 0.01). The ejection fraction improved from 23.1 +/- 6.6 % to 36 +/- 6.8 % at follow-up (p < 0.02). Freedom from readmission for heart failure was 85 %, 79 %, and 68 % at 1-, 2-, and 5 years, respectively.</AbstractText>Mitral valve surgery improves left ventricular function and reduces heart failure severity in patients with MR and cardiomyopathy. High-risk mitral valve surgery may be an alternative to heart transplantation in selected patients.</AbstractText> |
2,809 | ICD implantation with and without combined myocardial revascularisation--incidence of ICD therapy and late survival. | Our aim was to evaluate the occurrence of implanted cardioverter-defibrillator (ICD) shock and antitachycardia pacing (ATP), the effect of ICD therapies on mortality and the impact of revascularisation strategies on arrhythmic events.</AbstractText>We investigated 130 CAD patients undergoing ICD implantation between 1984 and 1999.</AbstractText>Freedom of shock was 66 +/- 7 %, 48 +/- 9 % and 48 +/- 9 % after 1, 3 and 5 years in patients with revascularisation and 62 +/- 8 %, 43 +/- 8 % and 23 +/- 11 % in patients without revascularisation, respectively; p = n. s. Freedom from ATP was similar in both groups - in patients with revascularisation, 64 +/- 6 %, 58 +/- 7 % and 58 +/- 7 % and without revascularisation 56 +/- 8 %, 51 +/- 9 % and 38 +/- 10 %, respectively; p = n. s. There were no significant differences in cumulative survival between patients with and without revascularisation; p = n. s.</AbstractText>CAD patients with VT/VF and with implanted ICD have, despite successful revascularisation, the same rate of device therapy and mortality as patients without an indication of revascularisation. This implies that patients with chronic ischemic heart disease and ventricular tachyarrhythmias continue to be at risk of sudden death after CABG/PTCA; evaluation for ICD implantation is warranted.</AbstractText> |
2,810 | Vasopressor response in a porcine model of hypothermic cardiac arrest is improved with active compression-decompression cardiopulmonary resuscitation using the inspiratory impedance threshold valve. | During normothermic cardiac arrest, a combination of active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) with the inspiratory threshold valve (ITV) significantly improves vital organ blood flow, but this technique has not been studied during hypothermic cardiac arrest. Accordingly, we evaluated the hemodynamic effects of ACD + ITV CPR before, and after, the administration of vasopressin in a porcine model of hypothermic cardiac arrest. Pigs were surface-cooled until their body core temperature was 26 degrees C. After 10 min of untreated ventricular fibrillation, 14 animals were randomly assigned to either ACD CPR with the ITV (n = 7) or to standard (STD) CPR (n = 7). After 8 min of CPR, all animals received 0.4 U/kg vasopressin IV, and CPR was maintained for an additional 10 min in each group; defibrillation was attempted after 28 min of cardiac arrest, including 18 min of CPR. Before the administration of vasopressin, mean +/- SEM common carotid blood flow was significantly higher in the ACD + ITV group compared with STD CPR (67 +/- 13 versus 26 +/- 5 mL/min, respectively; P < 0.025). After vasopressin was given at minute 8 during CPR, mean +/- SEM coronary perfusion pressure was significantly higher in the ACD + ITV group, but did not increase in the STD group (29 +/- 3 versus 15 +/- 2 mm Hg, and 25 +/- 1 versus 14 +/- 1 mm Hg at minute 12 and 18, respectively; P < 0.001); mean +/- SEM common carotid blood flow remained higher at respective time points (33 +/- 8 versus 10 +/- 3 mL/min, and 31 +/- 7 versus 7 +/- 3 mL/min, respectively; P < 0.01). Without active rewarming, spontaneous circulation was restored and maintained for 1 h in three of seven animals in the ACD + ITV group versus none of seven animals in the STD CPR group (not significant). During hypothermic cardiac arrest, ACD CPR with the ITV improved common carotid blood flow compared with STD CPR alone. Moreover, after the administration of vasopressin, coronary perfusion pressure was significantly higher during ACD + ITV CPR, but not during STD CPR.</AbstractText>New strategies are needed to improve the efficiency of cardiopulmonary resuscitation (CPR) in hypothermic cardiac arrest. Active compression-decompression CPR with the inspiratory threshold valve improved carotid blood flow (and coronary perfusion pressure with vasopressin) compared with standard CPR.</AbstractText> |
2,811 | Stenting of an unprotected left main coronary artery stenosis in cardiogenic shock and ventricular fibrillation: three-year follow-up. | We describe a case of stenting an unprotected left main coronary artery stenosis in an octogenarian patient with cardiogenic shock complicating acute myocardial infarction. Our patient had no in-stent restenosis of the left main for three years and remains asymptomatic. Since, in the octogenarian patient, the surgical risk for emergent coronary artery bypass graft is extremely high, coronary artery stenting of the unprotected left main for myocardial infarction complicated by cardiogenic shock is an alternative treatment in selected patients. |
2,812 | Characterisation of electrocardiogram signals based on blind source separation. | Blind source separation assumes that the acquired signal is composed of a weighted sum of a number of basic components corresponding to a number of limited sources. This work poses the problem of ECG signal diagnosis in the form of a blind source separation problem. In particular, a large number of ECG signals undergo two of the most commonly used blind source separation techniques, namely, principal component analysis (PCA) and independent component analysis (ICA), so that the basic components underlying this complex signal can be identified. Given that such techniques are sensitive to signal shift, a simple transformation is used that computes the magnitude of the Fourier transformation of ECG signals. This allows the phase components corresponding to such shifts to be removed. Using the magnitude of the projection of a given ECG signal onto these basic components as features, it was shown that accurate arrhythmia detection and classification were possible. The proposed strategies were applied to a large number of independent 3 s intervals of ECG signals consisting of 320 training samples and 160 test samples from the MIT-BIH database. The samples equally represent five different ECG signal types, including normal, ventricular couplet, ventricular tachycardia, ventricular bigeminy and ventricular fibrillation. The intervals analysed were windowed using either a rectangular or a Hamming window. The methods demonstrated a detection rate of sensitivity 98% at specificity of 100% using nearest neighbour classification of features from ICA and a rectangular window. Lower classification rates were obtained using the same classifier with features from either PCA or ICA and a rectangular window. The results demonstrate the potential of the new method for clinical use. |
2,813 | [Coupling ventilation and defibrillation]. | Fibrillation of the heart is one of the most common reasons for sudden death. In case of fibrillation, the brain gets damaged by hypoxia within minutes. Only a concept that bothly regards the cardial and pulmonal problem can be successful. A combination of AED (Automatic-External-Defibrillator) and breathing machine reduces the risks of hypoxia. It can furthermore benefit from the common use of sensors and a synchronised course. |
2,814 | Patient-dependent current dosing for semi-automatic external defibrillators (AED). | The improvements in semiconductors and modern circuitry allow new waveforms to be created for treating life-threatening heart fibrillation. A comparison of common waveforms shows that there is no definite optimal waveform. Especially in the case of early defibrillation by novices, the question of dosage should be re-discussed. While a physician may be able to dose the intensity of the therapeutic electric shock, one can't expect that from someone having no medical training. Common AEDs have predefined energy levels, that are delivered to a patient regardless of the patient's size and weight, etc. Current-based defibrillation provides a therapy matched to patient parameters, keeping the myocard stress as low as possible so that the heart has better chances of resuming a normal rhythm. |
2,815 | Removal of cardiopulmonary resuscitation artifacts from human ECG using an efficient matching pursuit-like algorithm. | We present a computationally efficient and numerically robust solution to the problem of removing artifacts due to precordial compressions and ventilations from the human electrocardiogram (ECG) in an emergency medicine setting. Incorporated into automated external defibrillators, this would allow for simultaneous ECG signal analysis and administration of precordial compressions and ventilations, resulting in significant clinical improvement to the treatment of cardiac arrest patients. While we have previously demonstrated the feasibility of such artifact removal using a multichannel Wiener filter, we here focus on an efficient matching pursuit-like approach making practical real-time implementations of such a scheme feasible for a wide variety of sampling rates and filter lengths. Using more realistic data than what have been previously available, we present evidence showing the excellent performance of our approach and quantify its computational complexity. |
2,816 | Computational framework for simulating the mechanisms and ECG of re-entrant ventricular fibrillation. | Ventricular arrhythmias remain an important cause of morbidity and mortality in the Western world. Although the underlying mechanisms of these arrhythmias can be studied experimentally, these investigations are in general limited to mapping electrical activity on the heart surface. Computational models of action potential propagation offer a potentially powerful way to study electrical activation and arrhythmias, but current models are not easy to link to the clinical environment. In this paper, we describe a framework for computing action potential propagation in which the geometry, electrophysiology and regional properties of ventricular myocardium can be specified so that, for example, different models for cardiac cellular electrophysiology can be used. We have computed action potential propagation during both normal beats and re-entry in an anatomically accurate model of ventricular geometry. By computing the resultant electric current flow in the torso we have also generated simulated ECG signals that result from specific activation patterns in the ventricular model. Models can be powerful tools for explaining observations, and this approach is able to provide a direct link between the different configurations of re-entry observed in computational and experimental studies, and the ECG signals observed in patients. |
2,817 | Detection of ventricular fibrillation and tachycardia from the surface ECG by a set of parameters acquired from four methods. | The recent development and increased application of automatic external defibrillators have prescribed very strong requirements towards ventricular fibrillation (VF) and fast ventricular tachycardia (VT > 180 bpm) detection from the surface electrocardiogram (ECG). We attempted to use informative parameters from several existing analysis methods and from a method developed in-house. A set of nine parameters was derived initially, with four of them being selected after statistical assessment. Detection of VF against non-shockable rhythms was obtained using the K-nearest neighbours classification method, with 98.6% specificity and 96.7% sensitivity. The detection accuracy remained high after inclusion of VT episodes above and below 180 bpm to shockable and non-shockable rhythms respectively and after the addition of noise. Test signals were taken from the well-known ECG signal databases of the American Heart Association and the Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH-'cudb' and 'vfdb' files). |
2,818 | Is left ventricular hypertrophy a risk factor in hypertensive patients? | Left ventricular hypertrophy (LVH) is supposed to be a risk factor of cardiovascular (CV) complications in hypertensive patients.</AbstractText>To compare clinical events in hypertensives with and without LVH.</AbstractText>319 hypertensives with LVH (mean age 64.1+/-10.6 ys) and 177 hypertensives without LVH (mean age 62.5+/-11.3 ys). LVH defined by echo Penn convention as left ventricular mass index >134 g/m2 in men and >110 g/m2 in women. Clinical events--heart failure (EF<40 %), left ventricular diastolic dysfunction (echo-doppler: transmitral-flow where peak A>peak E), myocardial infarction (history, ECG, cardiac enzymes), chronic atrial fibrillation (more than 2 weeks duration), mitral regurgitation (echo) and renal involvement (creatininemia>120 micromol/l). The two groups of hypertensives were matched by demographic criteria, duration and intensity of hypertension, obesity, diabetes mellitus, lipid serum levels and smoking habits.</AbstractText>There were statistically significant at least p<0.05 more CV events (heart failure, left ventricular diastolic dysfunction, myocardial infarction, chronic atrial fibrillation, and mitral regurgitation cases) and renal involvement in LVH-positive patients than in LVH-negative patients.</AbstractText>LVH is a strong risk factor for clinical events in hypertensives, which necessitates their more intensive treatment, mainly with drugs producing also LVH regression. (Tab. 5, Ref. 48.)</AbstractText> |
2,819 | August rats are more resistant to arrhythmogenic effect of myocardial ischemia and reperfusion than Wistar rats. | As differentiated from Wistar rats, myocardial ischemia and reperfusion produce no ventricular fibrillation in August rats. Pretreatment with nitric oxide synthase inhibitor Nw-nitro-L-arginine increased mortality rate in August rats with acute myocardial infarction from 20 to 40%. Under these conditions mortality rate in Wistar rats increased from 50 to 71%. Interstrain differences in the resistance of these animals to the arrhythmogenic effect of ischemia are probably associated with higher activity of the nitric oxide system in August rats compared to Wistar rats. |
2,820 | Precountershock cardiopulmonary resuscitation improves ventricular fibrillation median frequency and myocardial readiness for successful defibrillation from prolonged ventricular fibrillation: a randomized, controlled swine study. | After prolonged ventricular fibrillation (VF), precountershock cardiopulmonary resuscitation (CPR) will improve myocardial "readiness" for defibrillation compared with immediate defibrillation.</AbstractText>After 10 minutes of untreated VF, 32 swine (27+/-1 kg) were randomly assigned to receive immediate countershocks (DEFIB), CPR for 3 minutes followed by countershocks (CPR), or CPR for 3 minutes plus intravenous epinephrine followed by countershocks (CPR+EPI). VF waveform was evaluated by fast Fourier transformation.</AbstractText>VF amplitude and median frequency by fast Fourier transformation decreased during the untreated VF interval in all groups, and the median frequency subsequently increased during each minute of precountershock CPR. Although the VF median frequency in the 3 groups did not differ after 10 minutes of untreated VF (8.9+/-0.8 Hz versus 8.4+/-0.5 Hz versus 7.3+/-0.5 Hz, respectively), immediately before the first shock the VF median frequency was much lower in the DEFIB group than in either the CPR or CPR+EPI groups (8.9+/-0.8 Hz versus 13.1+/-0.8 Hz versus 13.8+/-0.9 Hz, respectively; P <.01). None of the 10 animals in the DEFIB group attained return of spontaneous circulation after the first set of shocks versus 5 of 10 animals in the CPR group and 6 of 12 animals in the CPR+EPI group (DEFIB versus each CPR group; P <.05). Cardiac output 1 hour after resuscitation was substantially worse in the DEFIB group than in the CPR or CPR+EPI groups (74+/-7 mL/kg per minute versus 119+/-7 mL/kg per minute versus 104+/-15 mL/kg per minute; P <.05).</AbstractText>Precountershock CPR can result in substantial physiologic benefits compared with immediate defibrillation in the setting of prolonged VF. Moreover, these benefits can be attained with or without the addition of intravenous epinephrine.</AbstractText> |
2,821 | Survival and neurologic outcome after cardiopulmonary resuscitation with four different chest compression-ventilation ratios. | The optimal ratio of chest compressions to ventilations during cardiopulmonary resuscitation (CPR) is unknown. We determine 24-hour survival and neurologic outcome, comparing 4 different chest compression-ventilation CPR ratios in a porcine model of prolonged cardiac arrest and bystander CPR.</AbstractText>Forty swine were instrumented and subjected to 3 minutes of ventricular fibrillation followed by 12 minutes of CPR by using 1 of 4 models of chest compression-ventilation ratios as follows: (1) standard CPR with a ratio of 15:2; (2) CC-CPR, chest compressions only with no ventilations for 12 minutes; (3) 50:5-CPR, CPR with a ratio of 50:5 compressions to ventilations, as advocated by authorities in Great Britain; and (4) 100:2-CPR, 4 minutes of chest compressions only followed by CPR with a ratio of 100:2 compressions to ventilations. CPR was followed by standard advanced cardiac life support, 1 hour of critical care, and 24 hours of observation, followed by a neurologic evaluation.</AbstractText>There were no statistically significant differences in 24-hour survival among the 4 groups (standard CPR, 7/10; CC-CPR, 7/10; 50:5-CPR, 8/10; 100:2-CPR, 9/10). There were significant differences in 24-hour neurologic function, as evaluated by using the swine cerebral performance category scale. The animals receiving 100:2-CPR had significantly better neurologic function at 24 hours than the standard CPR group with a 15:2 ratio (1.5 versus 2.5; P =.007). The 100:2-CPR group also had better neurologic function than the CC-CPR group, which received chest compressions with no ventilations (1.5 versus 2.3; P =.027). Coronary perfusion pressures, aortic pressures, and myocardial and kidney blood flows were not significantly different among the groups. Coronary perfusion pressure as an integrated area under the curve was significantly better in the CC-CPR group than in the standard CPR group (P =.04). Minute ventilation and PaO (2) were significantly lower in the CC-CPR group.</AbstractText>In this experimental model of bystander CPR, the group receiving compressions only for 4 minutes followed by a compression-ventilation ratio of 100:2 achieved better neurologic outcome than the group receiving standard CPR and CC-CPR. Consideration of alternative chest compression-ventilation ratios might be appropriate.</AbstractText> |
2,822 | Risk associated with pregnancy in hypertrophic cardiomyopathy. | We sought to assess mortality and morbidity in pregnant women with hypertrophic cardiomyopathy (HCM).</AbstractText>The risk associated with pregnancy in women with HCM is an important and increasingly frequent clinical issue for which systematic data are not available and a large measure of uncertainty persists.</AbstractText>Maternal mortality in 91 consecutively evaluated families with HCM was compared with that reported in the general population. The study cohort included 100 women with HCM with one or more live births, for a total of 199 live births. Morbidity related to HCM during pregnancy was investigated in 40 women evaluated within five years of their pregnancy.</AbstractText>Two pregnancy-related deaths occurred, both in patients at a particularly high risk. The maternal mortality rate was 10 per 1,000 live births (95% confidence interval [CI] 1.1 to 36.2/1,000) and was in excess of the expected mortality in the general Italian population (relative risk 17.1, 95% CI 2.0 to 61.8). In the 40 patients evaluated within close proximity of their pregnancy, 1 (4%) of the 28 who were previously asymptomatic and 5 (42%) of the 12 with symptoms progressed to functional class III or IV during pregnancy (p < 0.01). One patient had atrial fibrillation and one had syncope, both of whom had already experienced similar and recurrent events before their pregnancy.</AbstractText>Maternal mortality is increased in patients with HCM compared with the general population. However, absolute maternal mortality is low and appears to be principally confined to women at a particularly high risk. In the presence of a favorable clinical profile, the progression of symptoms, atrial fibrillation, and syncope are also uncommon during pregnancy.</AbstractText> |
2,823 | ST-segment elevation and ventricular fibrillation without coronary spasm by intracoronary injection of acetylcholine and/or ergonovine maleate in patients with Brugada syndrome. | The study examined whether patients with Brugada syndrome are sensitive to vagal stimulation or ischemia.</AbstractText>Experimental studies have suggested that a prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of the action potential dome in the epicardium, but not in the endocardium, give rise to ST-segment elevation and subsequent ventricular fibrillation (VF).</AbstractText>We evaluated the frequency of coronary spasm, augmentation (> or =0.1 mV) of ST-segment elevation in leads V(1) to V(3), and induction of VF by intracoronary injection of acetylcholine (ACh) and/or ergonovine maleate (EM) in 27 symptomatic patients with Brugada syndrome and 30 control subjects.</AbstractText>The coronary spasm was induced in 3 (11%) of the 27 patients with Brugada syndrome and in 13 (43%) of the 30 control subjects. ST-segment elevation was augmented by 11 (33%) of the 33 right coronary injections (ACh: 6/11 [55%]; EM: 5/22 [23%]), without coronary spasm, but not by any of the left coronary injections in patients with Brugada syndrome. Ventricular fibrillation was induced by 3 (9%) of the 33 right coronary injections (ACh: 2/11 [18%]; EM: 1/22 [5%]), but not by any of the left coronary injections. In contrast, neither ST-segment elevation nor VF was observed in any of the control subjects.</AbstractText>Our results support the hypothesis that mild ischemia and vagal influences act additively or synergistically with the substrate responsible for the Brugada syndrome to elevate the ST-segment and precipitate VF. These observations suggest that Brugada patients may be at a higher risk for ischemia-related sudden death.</AbstractText> |
2,824 | Paroxysmal postural dyspnea related to a left atrial ball thrombus. | We report herein an uncommon clinical observation of a 82-year-old woman with paroxysmal postural dyspnea related to a giant ball-thrombus located in the left atrium and partly protruding through the mitral orifice. No mitral stenosis was otherwise disclosed. The patient had a previous medical history of chronic atrial fibrillation without any anticoagulant therapy. The atrial mass was easily removed and the postoperative course was uneventful. Disclosure of such a free-floating ball-thrombus in the left atrial cavity requires prompt surgical treatment because of high risks of acute hemodynamic decompensation due to obstruction of the left ventricular inflow or, more rarely, systemic embolic events. |
2,825 | Implantable cardioverter defribrillator shocks: a troubleshooting guide. | Implantable cardioverter defibrillators deliver shocks in response to electrical signals that satisfy programmed criteria for detection of VT or VF. The first step in diagnosis of inappropriate shocks in patients with ICDs is to determine if the shock was delivered in response to a true tachyarrhythmia by inspecting data stored in the ICD. Shocks occur in the absence of tachyarrhythmias because nonarrhythmic physiologic or nonphysiologic signals are oversensed by the ICD and detected as arrhythmias. Diagnosis and causes of oversensing are reviewed. The second step in diagnosis is to determine if the tachyarrhythmia stored in the VT/VF episode log is VT/VF or SVT by analyzing stored electrograms. Frequent or repetitive shocks constitute an electrophysiologic emergency. The approach to this problem is reviewed. |
2,826 | Primary and secondary prevention of sudden cardiac death: the role of the implantable cardioverter defibrillator. | Sudden cardiac death (SCD) affects nearly 300,000 people each year in the U.S., and out-of-hospital rates for survival range from only 2% to 25%. A substantial reduction in SCD requires primary prevention through risk-stratification and secondary prevention of sustained ventricular tachycardia (VT-S) and ventricular fibrillation (VF). Because frequent premature ventricular complexes (PVCs) appeared to be associated with an increased risk for SCD in patients with significant ventricular dysfunction, it was thought that suppression of PVCs would prevent SCD. The implantable cardioverter defibrillator (ICD) electrically treats life-threatening VT-S and VF, and it can be implanted readily in the pectoral area. Two randomized, prospective, controlled trials demonstrated conclusively that the ICD is the treatment of choice in the primary prevention of SCD in patients with a previous MI. In addition, three randomized, controlled trials found the ICD to be superior to antiarrhythmic drugs in the secondary prevention of SCD. Physicians should learn to recognize patients who are candidates for the ICD and refer them to an electrophysiologist so that they can get this life-saving therapy. |
2,827 | Role of invasive EP testing in the evaluation and management of hypertrophic cardiomyopathy. | Hypertrophic cardiomyopathy (HCM) is an inheritable condition that may cause sudden death in the absence of significant symptoms or adverse morphological features. Therefore, there is a need for identification of those patients at sufficiently high risk to warrant prophylactic treatment. Risk stratification for primary prevention of sudden death has relied upon non-invasively derived markers of risk: syncope; a family history of premature sudden death; nonsustained ventricular tachycardia on Holter; abnormal blood pressure response to exercise; and severe left ventricular hypertrophy. The presence of two or more risk factors is associated with a 6-year sudden death survival rate of 72% (56-88%), justifying the consideration of prophylactic therapy. The 6-year sudden death survival rate in patients with one or no risk factors is 94% (91-98%). In these individuals the context and severity of the risk factor may guide the decision for prophylaxis; for example, a highly malignant family history carries greater justification than a large pedigree with only one sudden death. There is a need, however, for determining risk more accurately in those individuals with only one conventional risk factor. Programmed stimulation has been studied for its predictive value in primary prevention. 'Aggressive' protocols have been used and the most commonly induced arrhythmia is polymorphic ventricular tachycardia. These findings, however, are non-specific and of limited prognostic value. In addition the patients studied have been from selected high-risk populations without a low-risk cohort for comparison. Thus invasive EP studies appear to carry little advantage over non-invasive risk stratification. This is not surprising given that the mechanisms of cardiac arrest in HCM can be varied and may be modified by abnormal vascular responses and ischaemia. The relevance of invasively induced arrhythmias may therefore be limited. Other uses for electrophysiological study include the investigation and treatment of individuals with conduction disease and/or Wolff-Parkinson-White syndrome, atrial flutter and fibrillation and monomorphic ventricular tachycardia. Appropriate management may then involve radiofrequency ablation. A permanent pacemaker will be required if the atrio-ventricular node is ablated. |
2,828 | MADIT-II: clinical implications. | The MADIT-II trial showed that in patients with a prior myocardial infarction and ejection fraction </=0.30, prophylactic implantation of a defibrillator improves survival with a 31% reduction in mortality during an average follow-up of 20 months. Electrophysiologic inducibility was positive in 36% of patients at the time of ICD implantation. Inducibility was associated with increased ICD utilization for ventricular tachycardia during long-term follow-up, and decreased utilization for ventricular fibrillation. These preliminary findings raise questions about the clinical usefulness of electrophysiologic testing as a risk stratifier in patients with advanced left ventricular dysfunction. |
2,829 | The role of the transvenous catheter electrophysiologic study in the evaluation and management of ventricular tachyarrhythmias associated with ischemic heart disease. | The transvenous-catheter electrophysiologic (EP) study has occupied a central position in the investigation and management of patients with ischemic heart disease and a propensity to ventricular tachycardia (VT) or ventricular fibrillation (VF) for more than 25 years. However, demonstration of the superiority of the implantable cardioverter defibrillator (ICD) compared to other approaches to the management of VT/VF has resulted in a decrease in the frequency of use of the EP study in these patients. Nevertheless, the EP study remains a value-added procedure for many patients in this setting. These advantages include demonstration that the clinical arrhythmia is VT/VF when the diagnosis is uncertain, identification of those patients whose VT/VF is actually the result of a supraventricular tachyarrhythmia, identification of VT mechanisms readily amenable to catheter ablation, assessment of the response of a patient's VT to attempts at pace-termination, evaluation of candidacy for ablative VT therapy, prediction of the efficacy of approaches to prevention of VT/VF episodes, risk stratification of patients who have not yet experienced a sustained episode of VT/VF, and continued enhancement of our understanding of the mechanisms and therapeutics of VT/VF. The purpose of this review is to outline our present understanding of the techniques and indications for an EP study in patients with ischemic heart disease. |
2,830 | Catheter ablation or modulation of the AV node. | The ablate and pace strategy may be considered a viable therapy in the palliative management of patients with medically refractory highly symptomatic atrial fibrillation (AF). The overall success rate is approaching 100%, the inhospital course is usually event free, and the procedure is a relatively safe therapeutic option. There is no doubt that one of the major findings after atrioventricular (AV) node ablation is the significant reduction of cardiac symptoms and health care use, while exercise tolerance and quality of life significantly improved after the procedure. It is also well accepted that catheter ablation and pacemaker (PM) implantation are usually associated with significant improvement in left ventricular ejection fraction, particularly in patient with AF and reduced systolic function at baseline. On the other hand, AV node ablation seems unlikely to have a negative effect on long term survival. The mortality rate in some reports have raised concerns about excess deaths (mainly sudden deaths) attributable to AV node ablation and pacing therapy. These findings are not confirmed by recent data. Modulation of the AV node has been more recently introduced in the clinical practice in order to avoid permanent complete AV block and lifetime PM dependency. AV node modulation procedure is effective in approximately 70% of cases. The short duration of following periods does not allow to draw definitive conclusions concerning the potential evolution of AV node conduction disorders. Both AV node ablation and AV node modulation, when successful, are effective means to improve quality of life and cardiac performance in patients with medically refractory AF. The exact place of these procedures is, today, a matter of debate which is more controversial in patients with paroxysmal AF than with uncontrolled permanent AF. |
2,831 | New catheter ablation techniques for the treatment of cardiac arrhythmias. | Although established as the current standard in catheter ablation, radiofrequency energy has significant limitations. To produce a continuous line of conduction block, radiofrequency energy requires contact between the electrode and endocardium throughout and produces a lesion limited in depth and prone to endocardial disruption. As the predominant case mix of catheter ablation shifts from supraventricular tachycardias towards atrial fibrillation and ventricular tachycardia, interest has grown in alternative energy sources. Cryothermy offers the advantages of low risk of endocardial disruption and thrombus formation with extensive previous surgical experience in the treatment of cardiac arrhythmias. Ultrasound and microwave have the advantages of being contact forgiving and having excellent depth of penetration without an apparent higher risk of endocardial disruption than radiofrequency. Diode laser produces controlled low energy ablation and can be delivered through a range of optical fiber configurations including loops and balloons to produce thin continuous lesions. The use of optical fibers for laser delivery also provides an option for reflectance spectroscopy as a feedback mechanism on both contact as well as lesion progression in real time. Each of the above energy sources have potential clinical advantages in epicardial as well as endocardial ablation. |
2,832 | Hemodynamic and neurohumoral effects of selective endothelin A (ET(A)) receptor blockade in chronic heart failure: the Heart Failure ET(A) Receptor Blockade Trial (HEAT). | The endothelin (ET-1) system is activated in chronic heart failure (CHF). Whether, what type, and what degree of selective ET blockade is clinically beneficial is unknown. We investigated hemodynamic and neurohumoral effects of 3 weeks of treatment with various dosages of the orally available ET(A) antagonist darusentan in addition to modern standard therapy in patients with CHF.</AbstractText>A total of 157 patients with CHF (present or recent NYHA class III of at least 3 months duration), pulmonary capillary wedge pressure > or =12 mm Hg, and a cardiac index < or =2.6 L x min(-1) x m(-2) were randomly assigned to double-blind treatment with placebo or darusentan (30, 100, or 300 mg/d) in addition to standard therapy. Short-term administration of darusentan increased the cardiac index, but this did not reach statistical significance compared with placebo. The increase in cardiac index was significantly more pronounced after 3 weeks of treatment (P<0.0001 versus placebo). Pulmonary capillary wedge pressure, pulmonary arterial pressure, pulmonary vascular resistance, and right atrial pressure remained unchanged. Heart rate, mean artery pressure, and plasma catecholamines remained unaltered, but systemic vascular resistance decreased significantly (P=0.0001). Higher dosages were associated with a trend to more adverse events (including death), particularly early exacerbation of CHF without further benefit on hemodynamics compared with moderate dosages.</AbstractText>This study demonstrates for the first time in a large patient population that 3 weeks of selective ET(A) receptor blockade improves cardiac index in patients with CHF. However, long-term studies are needed to determine whether ET(A) blockade is beneficial in CHF.</AbstractText> |
2,833 | [Secondary and primary prevention of coronary heart disease: platelet aggregation inhibitors and anticoagulants]. | This review presents the results of primary and secondary prevention of coronary heart disease (CHD) with antiplatelet drugs and anticoagulants; therapeutic recommendations are derived. According to the results of the trials and due to its low price aspirin (ASS) can be still considered as the drug of choice. Its protective action has been documented for secondary prevention in patients with previous myocardial infarction, coronary angioplasty (PCI), unstable and stable angina, but not in patients with coronary artery bypass surgery, heart failure as well as in primary prevention. The doses recommended are 75-325 mg/d. If ASS is not tolerated clopidogrel is an alternative, but an expensive one. Anticoagulation for primary prevention of CHD may be considered in high risk patients, who do not tolerate ASS (alternative: clopidogrel). In secondary prevention anticoagulation is only recommended for special conditions, such as ASS intolerance (alternative: clopidogrel), ventricular aneurysm, ventricular thrombus, severe heart failure and/or atrial fibrillation. |
2,834 | History of cardiac rhythm disorders. | The history of cardiac rhythm disorders including antiarrhythmic drugs and electrotherapeutical tools is long and fascinating. In the beginning, there was not simply the anatomy and physiology of the heart, but also analysis of the pulse, which indicates the activity of the heart. Thus, like any other field of medicine, the study of arrhythmias has a distinctive past. Our current level of knowledge is not the result of a straight, linear progression any more than there is a static, established, monolithic body of thought dominating this field. Instead, our knowledge of arrhythmias today is the result of many competitive, sometimes serendipitous, scientific realizations, of which a few proved useful enough to pursue and eventually led to real advancements. Looking at the worldwide development of rhythmology it can be said that considerable contributions came from Germany in the last few centuries. Arrhythmology--past, present and future--includes clearly German investigators as pioneers of the field. The growing clinical importance of electric cardiac stimulation has been recognized and renewed as Zoll in 1952 described a successful resuscitation in cardiac standstill by external stimulation. The concept of a fully automatic implantable cardioverter-defibrillator system for recognition and treatment of ventricular flutter/fibrillation was first suggested in 1970. The first implantation of the device in a human being was performed in February 1980. By early 1997, 17 years after the first human implantation more than 100,000 ICD systems had been implanted worldwide. Further developments concern new pharmacological compounds, modern cardioverter-defibrillators, radiofrequency ablation, particularly pulmonary vein ablation in atrial fibrillation, innovative pacemakers including preventive pacing techniques, probably laser therapy and perhaps the automatic implantable pharmacological defibrillator. The advances in the field of therapeutic application of pharmacologic and electrical means as well as alternative methods will continue as rapidly as before in order to give us further significant aid in taking care of the patient. |
2,835 | Estimated global epicardial distribution of activation rate and conduction block during porcine ventricular fibrillation. | A proposed mechanism of the maintenance of ventricular fibrillation (VF) determined by studying small hearts or segments of large hearts is that a single stable rotor exists at the site of maximal activation rate, which gives rise to activation fronts that propagate into slower activating regions where they frequently block. We wished to determine if two predictions of this hypothesized mechanism are true during VF in large hearts: (1) there is a single maximum in the distribution of activation rates with the activation rate decreasing with distance away from this maximum; and (2) the incidence of block is greater outside than inside the fastest activating region.</AbstractText>Six 25-second episodes of VF from each of six pigs were recorded from 504 electrodes over the entire ventricular epicardium. The electrodes were divided into four zones: left ventricular base and apex (LVB and LVA) and right ventricular base and apex (RVB and RVA). A fast Fourier transform was performed on each electrogram, and the mean activation rate was estimated from the dominant (peak) frequency (DF) and block was estimated to be present during those time intervals when double peaks (DPs) were present in the power spectrum. The zones had statistically significant distributions of DF (LVB>LVA>RVA>RVB) and DP incidence (RVA>RVB>LVA>LVB).</AbstractText>During VF, the LV base has the highest estimated activation rate and the lowest estimated block incidence, and the RV has the slowest rate but the highest block incidence. This is consistent with the concept of VF being maintained by activation fronts originating from the LV base.</AbstractText> |
2,836 | Postresuscitation stunning: postfibrillatory myocardial dysfunction caused by reduced myofilament Ca2+ responsiveness after ventricular fibrillation-induced myocyte Ca2+ overload. | Resuscitation from ventricular fibrillation (VF), particularly from prolonged VF, frequently is complicated by postfibrillatory myocardial dysfunction (postresuscitation stunning). We tested whether this dysfunction can be caused by reduced myofilament Ca2+ responsiveness after VF-induced myocyte Ca2+ overload. We also tested whether electrical defibrillation shocks contribute to this dysfunction.</AbstractText>Myofilament Ca2+ responsiveness was estimated as ratio of left ventricular developed pressure over myocyte Ca2+ transient amplitudes (assessed as indo-1 fluorescence) in isolated perfused rat hearts before, during, and after VF (1.5 or 10 min) comparing three modes of defibrillation (biphasic electrical shocks, lidocaine, or spontaneous). We found that, independent of these defibrillation modes, myofilament Ca2+ responsiveness was significantly reduced, particularly after prolonged VF, although hearts were not ischemic or acidotic during and after VF (unchanged coronary flow, myocardial oxygen consumption, and pH of the coronary effluent). This reduction was associated with VF-induced myocyte Ca2+ overload and increasing or decreasing Ca2+ overload during VF (using 1 microM diltiazem or 6 mM extracellular calcium) led to parallel changes of myofilament Ca2+ responsiveness. However, myofilament Ca2+ responsiveness was not associated with the defibrillation shock energy (range 0.1-15.0 J/g wet heart weight).</AbstractText>Postfibrillatory myocardial dysfunction can be caused by reduced myofilament Ca2+ responsiveness after VF-induced myocyte Ca2+ overload. Electrical defibrillation shocks (up to 15 J/g wet heart weight), however, do not significantly contribute to this dysfunction. Our findings suggest that early additional therapy targeting intracellular Ca2+ overload may normalize myocyte Ca2+ and partially prevent postresuscitation stunning.</AbstractText> |
2,837 | Circadian and seasonal variation of malignant arrhythmias in a pediatric and congenital heart disease population. | Recent studies in adult populations have revealed seasonal variation in the frequency of acute cardiovascular events, including life-threatening arrhythmias, demonstrating increased events during winter and early spring. Trends in the time of day that arrhythmias occur also were noted. We sought to establish whether pediatric and young adult congenital heart disease implantable cardioverter defibrillator (ICD) recipients have circadian or seasonal variability in shock frequency, similar to adult populations.</AbstractText>Data from ICD patients at six pediatric centers in North America were analyzed to assess the timing of life-threatening arrhythmias. The populations consisted of children and adults with congenital heart disease and ICDs placed for malignant arrhythmias. Data were considered in 46 patients who received appropriate therapy (total 139 episodes) for ventricular tachycardia or ventricular fibrillation. Multiple variables were analyzed, including time of day, day of week, and month of year. In contrast to previously studied adult patients, fewer events occurred in the early morning (7.5%), with the most therapies occurring between 6 P.M. and midnight (35%). An increased frequency of therapies was observed in the fall and winter (September-January), representing 60% of all appropriate shocks. Unlike adult populations, Mondays did not have an increased frequency of malignant arrhythmias.</AbstractText>Pediatric and adult congenital heart disease populations have moderate seasonal and 24-hour variation in ICD event rate, with some distinctly different peaks than those seen in typical adult ICD populations. These findings suggest circadian variation in arrhythmia vulnerability that may differ from conventional occupational, physical, or emotional stressors. (J Cardiovasc Electrophysiol, Vol. 13, pp.</AbstractText> |
2,838 | [Two years experience with the Pericarbon stentless valve in Hungary]. | In 1999 stentless heart valves were introduced for treatment of the aortic valve disease in elderly patients at the Department of Cardiac Surgery of the University of Debrecen.</AbstractText><AbstractText Label="PATIENTS, METHODS" NlmCategory="METHODS">Between December 1999 and November 2001 63 patients underwent aortic valve replacement with Sorin Pericarbon stentless valve. The mean gradient was 80 +/- 11 mmHg, the left ventricular wall thickness was 15.5 +/- 0.7 mm and the ejection fraction was 54 +/- 8% preoperatively. 4 patients were in NYHA II, 47 in NYHA III and 12 in NYHA IV functional class. 42 patients had isolated aortic valve replacement, the remaining 21 patients underwent combined surgical procedure. The aortic x-clamp and perfusion times were 125 +/- 27 and 153 +/- 48 minutes respectively. Nine 21 mm, twenty-three 23 mm, seventeen 25 mm, twelve 27 mm and two 29 mm valves were implanted.</AbstractText>The hospital mortality was 6% (four patients). Transient atrial fibrillation was the most frequent postoperative complication. 77% of the patients had uneventful recovery and left hospital one week after surgery. Transthoracic echocardiography was performed at all patients before discharge and in December 2001. The mean follow up time was 9.7 +/- 5.8 months. 86% of the patients were in NYHA I functional class at the time of the follow up. The mean and peak transvalvular gradients were 9.4 +/- 4.1 mmHg and 16.1 +/- 6.8 mmHg respectively. The left ventricular wall thickness has decreased significantly (12.5 +/- 1.1 mm).</AbstractText>The Sorin Pericarbon stentless valve is an easily implantable valve replacement device. Due to the excellent hemodynamic properties and the unnecessary anticoagulation it could be safely used in elderly patients.</AbstractText> |
2,839 | Characteristics and outcome among patients having out of hospital cardiac arrest at home compared with elsewhere. | To describe the characteristics and outcome of patients who have a cardiac arrest at home compared with elsewhere out of hospital.</AbstractText>Subjects were patients included in the Swedish cardiac arrest registry between 1990 and 1999. The registry covers about 60% of all ambulance organisations in Sweden.</AbstractText>The study sample comprised patients reached by the ambulance crew and in whom resuscitation was attempted out of hospital. There was no age limit. Crew witnessed cases were excluded. The patients were divided into two groups: cardiac arrest at home and cardiac arrest elsewhere.</AbstractText>Among a study population of 24 630 patients the event took place at home in 16 150 (65.5%). Those in whom the arrest took place at home differed from the remainder in that they were older, were more often women, less often had a witnessed cardiac arrest, were less often exposed to bystander cardiopulmonary resuscitation (CPR), were less often found in ventricular fibrillation, and had a longer interval between collapse and call for ambulance, arrival of ambulance, start of CPR, and first defibrillation. Of patients in whom the arrest took place at home, 11.3% were admitted to hospital alive, v 19.4% in the elsewhere group (p < 0.0001); corresponding figures for survival after one month were 1.7% v 6.2% (p < 0.0001). The adjusted odds ratio for survival after one month (at home v not at home; considering age, sex, initial arrhythmia, bystander CPR, aetiology, and whether the arrest was witnessed) was 0.40 (95% confidence interval 0.33 to 0.49; p < 0.0001).</AbstractText>Sixty five per cent of out of hospital cardiac arrests in Sweden occur at home. The patients differed greatly from those with out of hospital cardiac arrests elsewhere, and fewer than 2% were alive after one month. Having an arrest at home was a strong independent predictor of adverse outcome. Further research is needed to identify the reasons for this.</AbstractText> |
2,840 | Prevalence of left ventricular systolic dysfunction and heart failure in high risk patients: community based epidemiological study. | To determine the prevalence of left ventricular systolic dysfunction, and of heart failure due to different causes, in patients with risk factors for these conditions.</AbstractText>Epidemiological study, including detailed clinical assessment, electrocardiography, and echocardiography.</AbstractText>16 English general practices, representative for socioeconomic status and practice type.</AbstractText>1062 patients (66% response rate) with previous myocardial infarction, angina, hypertension, or diabetes.</AbstractText>Prevalence of systolic dysfunction, both with and without symptoms, and of heart failure, in groups of patients with each of the risk factors.</AbstractText>Definite systolic dysfunction (ejection fraction <40%) was found in 54/244 (22.1%, 95% confidence interval 17.1% to 27.9%) patients with previous myocardial infarction, 26/321 (8.1%, 5.4% to 11.6%) with angina, 7/388 (1.8%, 0.7% to 3.7%) with hypertension, and 12/208 (5.8%, 3.0% to 9.9%) with diabetes. In each group, approximately half of these patients had symptoms of dyspnoea, and therefore had heart failure. Overall rates of heart failure, defined as symptoms of dyspnoea plus objective evidence of cardiac dysfunction (systolic dysfunction, atrial fibrillation, or clinically significant valve disease) were 16.0% (11.6% to 21.2%) in patients with previous myocardial infarction, 8.4% (5.6% to 12.0%) in those with angina, 2.8% (1.4% to 5.0%) in those with hypertension, and 7.7% (4.5% to 12.2%) in those with diabetes.</AbstractText>Many people with ischaemic heart disease or diabetes have systolic dysfunction or heart failure. The data support the need for trials of targeted echocardiographic screening, in view of the major benefits of modern treatment. In contrast, patients with uncomplicated hypertension have similar rates to the general population.</AbstractText> |
2,841 | Amiodarone-induced thyrotoxicosis: a case for surgical management. | Amiodarone can cause the development of thyroid dysfunction in patients with or without previous thyroid disease. Although most cases of amiodarone-induced thyrotoxicosis (AIT) are mild, a significant number become life threatening. Because of its pharmacokinetics, simply discontinuing amiodarone provides no relief and can worsen the patient's condition. Medical management frequently fails, and many patients cannot discontinue amiodarone because of its effect against resistant arrhythmias.</AbstractText>This retrospective chart review of a case at a tertiary care institution presents the case of a fifty-five-year-old male with dilated cardiomyopathy and no previous thyroid disease. The patient was in normal sinus rhythm on amiodarone for control of atrial fibrillation. He experienced the acute onset of symptoms with return to atrial fibrillation resistant to cardioversion. Physical examination, laboratory tests, and imaging findings were all consistent with a diagnosis of AIT. An attempt to withdraw amiodarone resulted in severe ventricular tachyarrhythmias.</AbstractText>Despite medical treatment, the patient's condition continued to deteriorate. Because amiodarone was the only effective drug, surgical treatment was elected. The patient underwent a total thyroidectomy and experienced no difficulties or complications. Postoperatively, the patient's condition improved, and he was successfully cardioverted.</AbstractText>Although an uncommon clinical entity, life-threatening AIT has been reported. Thyrotoxicosis can develop in any patient during or after amiodarone therapy. Medical management of this entity is extremely difficult because of the lack of a proven, consistent therapeutic armamentarium. Surgical management should be considered for patients whose conditions necessitate the continuation of amiodarone or those with severe symptoms resistant to medical therapy.</AbstractText>Copyright 2002, Elsevier Science (USA). All rights reserved.)</CopyrightInformation> |
2,842 | The isolated blood-perfused rat heart: an inappropriate model for the study of ischaemia- and infarction-related ventricular fibrillation. | 1. Well-characterized in vivo and in vitro models exist for the study of ischaemia- and infarction-related ventricular fibrillation (VF). In rats in vivo, VF appears to occur in distinct acute ischaemia- (early) and infarction-related (late) phases. Interestingly, isolated buffer-perfused rat hearts do not develop late VF. This raises the possibility that unidentified components of the blood may be responsible for late VF. We thus sought to characterize an isolated blood-perfused rat heart in order to investigate the possible influence of blood components on arrhythmias arising from ischaemia and infarction. 2. Hearts, excised from male Wistar rats, were perfused in the Langendorff mode with blood from support rats (male Wistar, 350-430 g) via an extracorporeal circuit. Perfused hearts underwent left coronary artery occlusion for 240 min or a sham procedure (n=10 group(-1)). 3. Only 10% of ischaemic hearts developed late VF (90-240 min). Tissue myeloperoxidase activity (an index of neutrophil accumulation) increased during ischaemia from 0.017+/-0.004 (six fresh hearts) to 0.056+/-0.005 units mg protein(-1) (P<0.05) at 240 min, but values were similar in sham hearts (0.083+/-0.013). Likewise, the decline (-1 vs 240 min of ischaemia shown) in circulating total white blood cells from 6.8+/-0.5 to 1.9+/-0.2 x 10(3) micro l(-1) and in platelets from 441+/-32 to 274+/-16 x 10(3) micro l(-1) (both P<0.05) was similar in time-matched sham hearts (data not shown). 4 Surprisingly, only 10% of ischaemic hearts developed early VF (0-90 min), although the incidence of early ventricular tachycardia was 100% in these hearts (P<0.05 vs sham hearts). Blood K+ values were normal (hyperkalaemia suppresses VF). 5 Although late VF was absent in blood-perfused hearts, it would be premature to conclude from this that late VF is not mediated by blood components. This is because the similar neutrophil accumulation in ischaemic and sham hearts, the decline in numbers of circulating blood components, and the unexpected paucity of early VF all question the validity of the model. |
2,843 | Atrial fibrillation in the elderly: facts and management. | Although atrial fibrillation is not widely known by the general public, in developed countries it is the most common arrhythmia. The incidence increases markedly with advancing age. Thus, with the growing proportion of elderly individuals, atrial fibrillation will come to represent a significant medical and socioeconomic problem. The consequences of atrial fibrillation have the greatest impact. The risk of thromboembolism is well known; other outcomes of atrial fibrillation are less well recognised, such as its relationship with dementia, depression and death. Such consequences are responsible for diminished quality of life and considerable economic cost. Atrial fibrillation is characterised by rapid and disorganised atrial activity, with a frequency between 300 and 600 beats/minute. The ventricles react irregularly, and may contract rapidly or slowly depending on the health of the conduction system. Clinical symptoms are varied, including palpitations, syncope, dizziness or embolic events. Atrial fibrillation may be paroxysmal, persistent or chronic, and a number of attacks are asymptomatic. Suspicion or confirmation of atrial fibrillation necessitates investigation and, as far as possible, appropriate treatment of underlying causes such as hypertension, diabetes mellitus, hypoxia, hyperthyroidism and congestive heart failure. In the evaluation of atrial fibrillation, cardiac exploration is invaluable, including electrocardiogram (ECG) and echocardiography, with the aim of detecting cardiac abnormalities and directing management. In elderly patients (arbitrarily defined as aged >75 years), the management of atrial fibrillation varies; it requires an individual approach, which largely depends on comorbid conditions, underlying cardiac disease, and patient and physician preferences. This management is essentially based on pharmacological treatment, but there are also nonpharmacological options. Two alternatives are possible: restoration and maintenance of sinus rhythm, or control of ventricular rate, leaving the atria in arrhythmia. Pharmacological options include antiarrhythmic drugs, such as class III agents, beta-blockers and class IC agents. These drugs have some adverse effects, and careful monitoring is necessary. The nonpharmacological approach to atrial fibrillation includes external or internal direct-current cardioversion and new methods, such as catheter ablation of specific foci, an evolving science that has been shown to be successful in a very select group of atrial fibrillation patients. Another serious challenge in the management of chronic atrial fibrillation in older individuals is the prevention of stroke, its primary outcome, by choosing an appropriate antithrombotic treatment (aspirin or warfarin). Several risk-stratification schemes have been validated and may be helpful to determine the best antithrombotic choice in individual patients. |
2,844 | [Right atrial lipoma with calcification in ascending aorta; report of a case]. | A 67-year-old male was diagnosed to have a right atrial tumor by echocardiography incidentally. Computed tomography (CT) indicated a mass which showed very low radiodensity and magnetic resonance imaging (MRI) [T1-weighted] showed the high signal intensity of tumor. We could predict the mass as lipoma. Tumor removal was performed under cardio-pulmonary bypass and under ventricular fibrillation because of the calcification in ascending aorta. Microscopically the tumor was consisted of mature adipose tissue. The postoperative course was uneventful. Cardiac lipomas are rare tumors. CT and MRI are better investigations for preoperative diagnosis. After surgical excision the prognosis is excellent. |
2,845 | Alpha 2-Adrenergic stimulation is protective against ischemia-reperfusion-induced ventricular arrhythmias in vivo. | We previously reported that alpha(2)-adrenergic receptor (alpha(2)-AR) stimulation in Purkinje fibers in vitro prolongs action potential duration and suppresses beta-adrenergic-induced delayed afterdepolarizations and sustained triggered activities. We examined the effects of alpha(2)-AR stimulation on reperfusion-induced ventricular arrhythmias [ventricular tachycardia/ventricular fibrillation (VT/VF)] in vivo. Arterial blood pressure, heart rate, surface electrocardiogram, and renal sympathetic nerve activities were recorded simultaneously in Sprague-Dawley rats. The incidence of VT/VF was 87.5% for controls, 50% for the beta-blocker group, 72% for the alpha(1)-blocker group, and 12.5% for the alpha(1) + beta-blockers group (unopposed alpha(2)-adrenergic activation). Direct alpha(2)-AR stimulation with UK-14304 also prevented VT/VF. These effects were reversed by the alpha(2)-adrenergic antagonist yohimbine. Increases in renal sympathetic nerve activity were associated with left anterior descending coronary artery ligation and reperfusion (33 +/- 1.5 and 62 +/- 1.7% over baseline, respectively) in controls. Similar patterns were observed among all experimental groups irrespective of the incidence of VT/VF on reperfusion. We conclude that alpha(2)-AR stimulation has a potent antiarrhythmic effect on ischemia-reperfusion-induced VT/VF in vivo and that this effect is not centrally mediated. |
2,846 | Effects of acute reduction of temperature on ventricular fibrillation activation patterns. | Because of its electrophysiological effects, hypothermia can influence the mechanisms that intervene in the sustaining of ventricular fibrillation. We hypothesized that a rapid and profound reduction of myocardial temperature impedes the maintenance of ventricular fibrillation, leading to termination of the arrhythmia. High-resolution epicardial mapping (series 1; n = 11) and transmural recordings of ventricular activation (series 2; n = 10) were used to analyze ventricular fibrillation modification during rapid myocardial cooling in Langendorff-perfused rabbit hearts. Myocardial cooling was produced by the injection of cold Tyrode into the left ventricle after induction of ventricular fibrillation. Temperature and ventricular fibrillation dominant frequency decay fit an exponential model to arrhythmia termination in all experiments, and both parameters were significantly correlated (r = 0.70, P < 0.0001). Termination of the arrhythmia occurred preferentially in the left ventricle and was associated with a reduction in conduction velocity (-60% in left ventricle and -54% in right ventricle; P < 0.0001) and with activation maps predominantly exhibiting a single wave front, with evidence of wave front extinction. We conclude that a rapid reduction of temperature to <20 degrees C terminates ventricular fibrillation after producing an important depression in myocardial conduction. |
2,847 | Safety and efficacy of advanced atrial pacing therapies for atrial tachyarrhythmias in patients with a new implantable dual chamber cardioverter-defibrillator. | This study evaluated the safety and efficacy of atrial pacing therapies for the treatment and prevention of atrial tachycardia (AT) or atrial fibrillation (AF) in a new dual chamber implantable cardioverter defibrillator (ICD).</AbstractText>Patients with an ICD may also experience AT or AF that is amenable to pace termination.</AbstractText>The efficacy of atrial antitachycardia pacing (ATP) therapies for atrial tachycardia or atrial fibrillation (AT/AF) was determined in 151 patients after implantation of a GEM III AT ICD (Medtronic Inc., Minneapolis, Minnesota). The percentage of episodes successfully terminated was adjusted for multiple episodes per patient.</AbstractText>A total of 717 of 728 (96%) episodes classified as AT or AF were judged to be appropriate detections. By device classification, atrial ATP terminated 187 of 383 (40% adjusted) episodes classified as AT compared with 65 of 240 episodes classified as AF (26% adjusted, p = 0.013). Atrial Ramp or Burst+ ATP terminated 184 of 378 episodes of AT (39% adjusted), whereas 50-Hz Burst pacing therapy terminated only 12 of 109 episodes of AT (12% adjusted) and 65 of 240 episodes of AF (26% adjusted). If efficacy was defined as termination of AT/AF within 20 s of delivery of the pacing therapy, ATP therapies terminated 139 of 383 (32% adjusted) episodes of AT compared with 34 of 240 episodes of AF (15% adjusted, p = 0.003). Efficacy was dependent on AT cycle length. Frequent transitions between AT and AF predicted inefficacy of atrial ATP (p < 0.001). Ventricular proarrhythmia secondary to atrial ATP was not observed.</AbstractText>Atrial ATP therapies terminate many episodes of AT without ventricular proarrhythmia. The addition of 50-Hz Burst pacing has minimal efficacy for AT/AF.</AbstractText> |
2,848 | Left ventricular diastolic dysfunction as a predictor of the first diagnosed nonvalvular atrial fibrillation in 840 elderly men and women. | The objective of this study was to determine whether diastolic dysfunction is associated with increased risk of nonvalvular atrial fibrillation (NVAF) in older adults with no history of atrial arrhythmia.</AbstractText>Few data exist regarding the relationship between diastolic function and NVAF.</AbstractText>The clinical and echocardiographic characteristics of patients age > or =65 years who had an echocardiogram performed between 1990 and 1998 were reviewed. Exclusion criteria were history of atrial arrhythmia, stroke, valvular or congenital heart disease, or pacemaker implantation. Patients were followed up in their medical records to the last clinical visit or death for documentation of first AF.</AbstractText>Of 840 patients (39% men; mean [+/- SD] age, 75 +/- 7 years), 80 (9.5%) developed NVAF over a mean (+/- SD) follow-up of 4.1 +/- 2.7 years. Abnormal relaxation, pseudonormal, and restrictive left ventricular diastolic filling were associated with hazard ratios of 3.33 (95% confidence interval [CI], 1.5 to 7.4; p = 0.003), 4.84 (95% CI, 2.05 to 11.4; p < 0.001), and 5.26 (95% CI, 2.3 to 12.03; p < 0.001), respectively, when compared with normal diastolic function. After a number of adjustments, diastolic function profile remained incremental to history of congestive heart failure and previous myocardial infarction for prediction of NVAF. Age-adjusted Kaplan-Meier five-year risks of NVAF were 1%, 12%, 14%, and 21% for normal, abnormal relaxation, pseudonormal, and restrictive diastolic filling, respectively. CONCLUSIONS; The presence and severity of diastolic dysfunction are independently predictive of first documented NVAF in the elderly.</AbstractText> |
2,849 | Serious ventricular arrhythmias among users of cisapride and other QT-prolonging agents in the United States. | To evaluate the risk of serious ventricular arrhythmia (SVA) with cisapride use in the United States.</AbstractText>The study population included 28,078 patients under the age of 65 years who received cisapride between 1993 and 1998 with no history of antiarrhythmia treatment. Each follow-up day was classified according to use of cisapride and other factors. Outcomes of SVAs were identified using medical claims records and National Death Index search, and confirmed by medical record review. Rates of events were calculated for time on and off cisapride. Poisson regression analysis was used to calculate adjusted rate ratios.</AbstractText>There were 23 cases of SVAs; 10 during periods of cisapride use and 13 during periods of non-use. The adjusted rate ratio comparing SVA events in cisapride use time to non-use time was 1.60 (95% CI: 0.67-3.82), and that identified for the other QT-prolonging drugs was 1.60 (95% CI: 0.65-3.98).</AbstractText>The evidence for an increased risk of SVAs associated with cisapride was equivocal after taking observation time on and off cisapride into account, and adjusting for risk factors, though we cannot exclude the possibility of a 3.8-fold increased risk. Overall, the plausible risks of cisapride were similar to those of other QT-prolonging drugs.</AbstractText> |
2,850 | [The first Japanese case of autosomal dominant Emery-Dreifuss muscular dystrophy with a novel mutation in the lamin A/C gene]. | Emery-Dreifuss muscular dystrophy (EDMD) is a muscular disorder characterized by 1) early contracture of the elbows. Achilles tendons and post-cervical muscles, 2) slowly progressive muscle wasting and weakness with a humeroperoneal distribution, and 3) life-threatening cardiomyopathy with conduction block. Most of families with EDMD show X-linked recessive inheritance with mutations in the STA gene on chromosome Xq28, which encodes a protein named emerin. A rare autosomal dominant form of EDMD (AD-EDMD) is caused by mutations in lamin A/C gene (LMNA) on chromosome 1q21. Both emerin and lamin A/C are located in the inner surface membrane of the nucleus. A 49-year-old woman was skinny and slow runner from childhood and suspected as having a certain muscular disorder. At 35 years, she was found to have the second degree atrioventricular block. At 45 years, she was admitted to a hospital for right-side hemiplegia after cerebral infarction. Cardiac involvement was also observed including high degree atrioventricular block with chronic atrial fibrillation and frequent paroxysmal ventricular contraction on the electrocardiogram. At 49 years, she was referred to our hospital for further evaluation. She had possible dilated cardiomyopathy with conduction block. She also had muscular atrophy and weakness in all extremities, predominantly in the right-side, and contracture of bilateral Achilles tendon, knee and elbow joints, and postcervical muscles. Biopsied skeletal muscle and electromyogram showed myopathic changes. Since a novel point mutation of Ser303Pro was found in exon 5 of LMNA gene, she was diagnosed as having AD-EDMD and had a permanent pacemaker implantation. Her daughter also had some abnormalities on electrocardiogram. This is the first Japanese case of AD-EDMD. Amiodaron was effective for non-sustained ventricular tachycardia. Early diagnosis and following cardiological examinations and treatments are important and necessary to improve the prognosis of the patients with EDMD. |
2,851 | Ibutilide-induced long QT syndrome and torsade de pointes. | Ibutilide is a class III antiarrhythmic agent used for the termination of atrial fibrillation and atrial flutter. It mainly affects membrane potassium currents and prolongs the cardiac action potential. This effect is reflected as QT interval prolongation on the surface electrocardiogram. Like other drugs that affect potassium currents, ibutilide is prone to induce a malignant ventricular tachycardia, torsade de pointes. We report four cases of torsade de pointes after administration of ibutilide for pharmacologic cardioversion of atrial fibrillation and atrial flutter; three of these cases required direct current cardioversion for termination of torsade de pointes. All four patients were female. We discuss the risk factors for development of ibutilide-induced torsade de pointes. |
2,852 | A novel TPM1 mutation in a family with hypertrophic cardiomyopathy and sudden cardiac death in childhood. | We sought to define the pathogenic mutation in a family with hypertrophic cardiomyopathy (HC) and a markedly arrhythmogenic phenotype. The proband was an 8-year-old female with a sentinel event of sudden death. Screening echocardiograms revealed HC in 2 of her 3 siblings and her father. Her youngest male sibling was diagnosed with HC at age 2 years and died suddenly at age 6 years from ventricular fibrillation despite an implanted cardioverter defibrillator. Using DNA extracted from peripheral lymphocytes, linkage exclusion was performed by haplotype analysis of polymorphic markers for the HC genes. Genes not excluded by linkage were analyzed for mutations using denaturing high-performance liquid chromatography (DHPLC) and direct DNA sequencing. Using this strategy, a 610 T>G nucleotide substitution in the alpha-tropomyosin gene (TPM1) was identified resulting in a novel L185R (Leucine [L] to Arginine [R]) missense mutation. This mutation was a spontaneous germ-line mutation originating in the proband's father. L185R-TPM1 cosegregated with family members having clinical evidence of HC, including the proband as confirmed by molecular autopsy. The mutation was not present in 400 reference alleles. Thus, a novel missense mutation in TPM1 was discovered in a family with HC and sudden death in childhood. Unlike previously defined mutations that may disrupt the interactions between alpha-tropomyosin monomers, the L185R mutation may affect troponin-T binding. Defining the pathogenic mutation enabled definitive molecular diagnosis of 2 surviving children. |
2,853 | [Effects of myocardial stretching on excitation frequencies determined by spectral analysis during ventricular fibrillation]. | The aim of this study was to analyze the effects of myocardial stretching on excitation frequencies, as determined by spectral analysis, during ventricular fibrillation.</AbstractText>In 12 isolated rabbit heart preparations, ventricular activation during ventricular fibrillation was recorded with multiple electrodes. Recordings were obtained before, during and after ventricular dilatation produced with an intraventricular balloon. The dominant frequency of the signals obtained with each of the electrodes was determined by spectral analysis.</AbstractText>During the control phase, the mean, minimum and maximum dominant frequencies were, respectively, 14.3 1.7, 12.5 1.7, and 16.2 1.4 Hz, and the average difference between the maximum and minimum frequencies was 3.6 2.1 Hz. This difference was over 4 Hz in four cases, and in no case did it exceed 8 Hz. During ventricular stretching, the mean dominant frequency increased significantly (21.1 6.1 Hz; p < 0.0001), as did the minimum values (14 2.6 Hz; p < 0.05) and especially the maximum values (26.6 7.7 Hz; p < 0.0001). The difference between the maximum and minimum frequencies (12.6 6.4 Hz; p < 0.001) was over 4 Hz in all cases except one, and over 8 Hz in 9 cases. The maximum values were distributed heterogeneously during ventricular stretching. Upon suppressing ventricular stretching, the dominant frequency did not differ from controls.</AbstractText>Myocardial frequency maps during ventricular fibrillation show limited variations in the dominant frequency of the signals recorded in the lateral wall of the left ventricle. During stretching, the patterns were heterogeneous, due mainly to the marked increase in the maximum dominant frequency. In the experimental model used, the effects of stretching remitted after suppressing ventricular dilatation.</AbstractText> |
2,854 | Inhibition of angiotensin-converting enzyme reduces susceptibility of hypertrophied rat myocardium to ventricular fibrillation. | Left ventricular (LV) hypertrophy increases susceptibility to reperfusion arrhythmias and the angiotensin-converting enzyme inhibitor, ramipril, may reduce that susceptibility via regression of LV hypertrophy. Rats (n=12 per group) were subjected to abdominal aortic constriction (AC) or sham-operation (SH) and from 3 to 6 weeks after surgery, 3 AC groups received ramipril (0.01, 0.1, or 1 mg/kg per day p.o.) while the SH and 1 AC group received vehicle. Six weeks after surgery (ie after 3 weeks of treatment), the hearts were excised and subjected to independent Langendorf perfusion of left and right coronary beds. The left coronary bed was then subjected to ischemia (7 min) and reperfusion (5 min). Hypertrophied hearts from the vehicle AC group showed a significant increase in the incidence of reperfusion-induced ventricular fibrillation (VF) compared with control hearts from the SH group (92%* vs 33%: *p<0.05); this difference was abolished by ramipril (42%, 50%, and 42%, at 0.01, 0.1, or 1 mg/kg per day, respectively). The LV weight/body weight ratio was significantly increased in all AC groups (regardless of ramipril treatment) relative to the SH group. At the cellular level, myocyte length was significantly increased in the vehicle AC group, but was normalized by ramipril treatment (1 mg/kg per day). At the molecular level, atrial natriuretic factor (ANF) mRNA expression was also significantly increased in the vehicle AC group, but was again normalized by ramipril treatment (1 mg/kg per day). In conclusion, short-term treatment with ramipril reduced susceptibility to severe ventricular arrhythmias in hypertrophied rat hearts. This protection was achieved in the absence of a significant reduction in LV weight, but was accompanied by regression of myocyte hypertrophy, as reflected by reductions in cell size and ANF expression. |
2,855 | Chemoreflex sensitivity as a predictor of arrhythmia relapse in ICD recipients. | The chemoreflex sensitivity as a marker of a disturbed vagal reflex activity has proved to be a parameter of increased risk for ventricular tachyarrhythmias or sudden cardiac death. The sensitivity of patients with prior myocardial infarction concerning ventricular tachyarrhythmias amounted to about 70%. This prospective study should evaluate the positive predictive accuracy of this new method in patients at risk for ventricular arrhythmias.</AbstractText>42 patients were enrolled into this study. All had a prior myocardial infarction at least 6 months previously; 35 patients were resuscitated from sudden cardiac death, and seven patients had documented monomorphic ventricular tachycardias. All patients were recipients of an ICD. The chemoreflex sensitivity was measured by determination of the venous partial pressure of oxygen and the heart rate before and after inhalation of pure oxygen. The difference in the RR-intervals before and after inhalation divided by the difference in the oxygen pressures were calculated as the chemoreflex sensitivity [ms/mmHg]. Furthermore, in all patients additional risk stratifiers used in this study were the presence of ventricular late potentials (LP), the short-term heart rate variability (HRV), the baroreflex sensitivity (BRS) and a decreased left ventricular function (ejection fraction<40%, EF).</AbstractText>The chemoreflex sensitivity in the patient group as a whole amounted to 2.59+/-2.06 ms/mmHg. During follow-up, out of the 42 patients enrolled, 20 had a documented arrhythmic event (AE: sustained ventricular tachycardia or ventricular fibrillation). Patients with and without AE showed significantly different values of chemoreflex sensitivity (1.58+/-1.09 vs. 3.51+/-2.31 ms/mmHg, P<0.01) and EF (33.3+/-15.6 vs. 47.9+/-17.9%, P<0.05), but not of LP, HRV or BRS. The relative risk of reduced chemoreflex sensitivity concerning an AE amounted to 2.83 (95% CI 0.99-8.01).</AbstractText>The chemoreflex sensitivity as a marker of increased risk for ventricular tachyarrhythmias shows a high positive predictive power in patients with prior myocardial infarction and who previously survived ventricular tachyarrhythmias. These results should be confirmed by studies in broad populations and without survived arrhythmic event.</AbstractText> |
2,856 | Comparative effects of permanent biventricular and right-univentricular pacing in heart failure patients with chronic atrial fibrillation. | One third of chronic heart failure patients have major intraventricular conduction and uncoordinated ventricular contraction. Non-controlled studies suggest that biventricular pacing may improve haemodynamics and well-being by reducing ventricular asynchrony. The aim of this trial was to assess the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation.</AbstractText>Fifty nine NYHA class III patients with left ventricular systolic dysfunction, chronic atrial fibrillation, slow ventricular rate necessitating permanent ventricular pacing, and a wide QRS complex (paced width >or=200 ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, crossover study compared the patients' parameters, as monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. The primary end-point was the 6-min walked distance, secondary end-points were peak oxygen uptake, quality-of-life, hospitalizations, patients' preferred study period and mortality.</AbstractText>Because of a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, we did not observe a significant difference. However, in the patients with effective therapy the mean walked distance increased by 9.3% with biventricular pacing (374+/-108 vs 342+/-103 m in univentricular;P =0.05). Peak oxygen uptake increased by 13% (P=0.04). Hospitalizations decreased by 70% and 85% of the patients preferred the biventricular pacing period (P<0.001).</AbstractText>As compared with conventional VVIR pacing, effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes. Further randomized controlled studies are required to definitively validate this therapy in such patients.</AbstractText>Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved.</CopyrightInformation> |
2,857 | Catecholaminergic polymorphic ventricular tachycardia in a 3-year-old with occult myocarditis. | Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare clinical entity in children. Occult myocarditis has not been previously implicated as an etiologic agent. A 3-year-old female presents with a presumed breath-holding spell and is found to have ventricular fibrillation requiring DC cardioversion. An invasive electrophysiological study was performed demonstrating the absence of inducible ventricular arrhythmias. Low dose epinephrine confirmed the presence CPVT. Right ventricular endomyocardial biopsies sent for polymerase chain reaction (PCR) analysis demonstrated the presence of adenoviral DNA. The authors hypothesize that occult myocarditis may be the inciting agent for CPVT in children. |
2,858 | Inhibition of bradycardia pacing and detection of ventricular fibrillation due to far-field atrial sensing in a triple chamber implantable cardioverter defibrillator. | Oversensing of intracardiac signals or myopotentials may cause inappropriate ICD therapy. Reports on far-field sensing of atrial signals are rare, and inappropriate ICD therapy due to oversensing of atrial fibrillation has not yet been described. This report presents a patient with a triple chamber ICD and a history of His-bundle ablation who experienced asystolic ventricular pauses and inappropriate detection of ventricular fibrillation due to far-field oversensing of atrial fibrillation. Several factors contributed to the complication, which resolved after reduction of the ventricular sensitivity. |
2,859 | [Alternatives to chronic cardiac stimulation in patients with mechanical tricuspid prosthesis and atrioventricular block]. | One of the complications of tricuspid valve replacement (TVR) is the complete heart block (CHB). In these patients an epicardial permanent pacemaker is frequently used but its insertion is another major operation and higher thresholds are needed. Two patients are reported, both women, with rheumatic heart disease and TVR who required a permanent pacemaker because they developed CHB. The first patient underwent mitral valve replacement with a disc valve seventeen years before and TVR recently. A single chamber pacemaker was implanted. Left ventricular pacing was achieved through the great cardiac vein. The acute and chronic pacing thresholds were adequate. The second patient underwent tricuspid and mitral replacement with a Starr-Edwards (SE) valve. Eighteen years later this patient had atrial fibrillation with slow ventricular response and heart failure. The pacemaker lead had to be inserted across the tricuspid SE valve because ventricle pacing through the coronary veins was unsuccessful. The endocardial pacing resulted in mild tricuspid regurgitation and has continued the same way for four years. To conclude, ventricle pacing through the coronary veins is safe, produces excellent results and fewer complications. On the other hand, ventricle pacing across a prosthetic tricuspid valve remains questionable because of possible damage to the prosthesis itself leading to valve insufficiency and because of damage to the pacing lead. |
2,860 | [Follow-up of a group of patients with automatic implantable defibrillator]. | The automatic implantable defibrillator (AID) is the treatment of choice for primary and secondary prevention of sudden death. At the Instituto Nacional de Cardiología, since October 1996 until January 2002, 25 patients were implanted with 26 AID. There were 23 men (92%) and the mean age of the whole group, was 51.4 years. Twenty-three patients (92%) presented structural heart disease, the most common was ischemic heart disease in 13 patients (52%), with a mean ejection fraction of 37.8%. One patient without structural heart disease had Brugada Syndrome. The most frequent clinical arrhythmia was ventricular tachycardia in 14 patients (56%). The mean follow-up was of 29.3 months during which a total of 30 events of ventricular arrhythmia were treated through AID; six of them were inappropriate due to paroxismal atrial fibrillation; 10 AID patients (34%) have not applied for therapy. Three patients (12%) of the group died due to congestive heart failure refractory to pharmacologic treatment.</AbstractText>The implant of the AID is a safe and effective measure for primary and secondary prevention of sudden death. World-wide experience evidences, that this kind of device has not modified the mortality rate due to heart failure in these patients, but it has diminished sudden arrhythmic death.</AbstractText> |
2,861 | [Perpetual cardiac fibrillation and predictors of sudden cardiac arrhythmic death in patients with ischemic stroke]. | To study predictors of sudden cardiac arrhythmic death in patients with perpetual cardiac fibrillation (PCF) and ischemic stroke.</AbstractText>230 patients with ischemic stroke were examined. 22 (9.6%) patients of them (group 1) had PCF, 208 (90.4%) patients (group 2) had sinus rhythm. The groups were matched by sex, stage of ischemic stroke, presence of ischemic heart disease. Echocardiography and Holter monitoring were made in all the examinees.</AbstractText>Zones of left ventricular dyskinesia and high-grade extrasystoles occurred more frequently in group 1. Ventricular extrasystoles were also frequent in this group. A close correlation was found between the zones of left ventricular dyskinesis and ventricular extrasystoles of high gradations.</AbstractText>Thus, most of the patients with ischemic stroke and PCF have ventricular arrhythmia resultant from systolic dysfunction of the left ventricle and related to the risk of sudden cardiac death.</AbstractText> |
2,862 | Is the presence of interatrial septal hypertrophy a marker for atrial fibrillation in the elderly? | Interatrial septal thickness (IST) appears to increase with heart weight, body surface area, and the presence of vacuolated fat cells within the atrial septum. The increased thickness of the atrial septum is an infrequently observed but readily recognized entity by echocardiography. Several reports have suggested that some cardiac arrhythmias, particularly those of atrial origin, may be a consequence of this fatty deposition. However, to date, no study has correlated the presence of atrial fibrillation with IST in the elderly. This is of particular importance as this rhythm is so prevalent in this population. Accordingly, a retrospective analysis was conducted in a group of 40 patients, age 65 and older, to measure IST using transthoracic echocardiography. Furthermore, measurements of right and left atrial size, body surface area, left ventricular wall thickness, and left ventricular ejection fraction were recorded. Group I consisted of 20 patients with known atrial fibrillation (eight males and 12 females; mean age 78+/-8 years) and group II consisted of 20 patients in normal sinus rhythm (three males and 17 females; mean age 74+/-6 years). There was no difference between the two groups in terms of body surface area (1.83 vs. 1.79 m2; p<0.78); left ventricular wall thickness (1.16 vs. 1.12 cm; p<0.58); and left ventricular ejection fraction (48% vs. 55%; p<0.17). Group I had somewhat larger right atrial (4.2 vs. 3.4 cm; p<0.001) and left atrial (4.7 vs. 4.1 cm; p<0.02) dimensions than group II. Furthermore, IST was found to be the most significant variable that differentiated patients with atrial fibrillation from patients with normal sinus rhythm (1.39 vs. 0.85 cm; p<0.0001). Even after adjusting for all the covariables, IST remained statistically significant (p<0.0001). The findings of this pilot study show a strong correlation between IST and atrial fibrillation. Although the stimulus for the increased thickness of the atrial septum remains elusive, IST may identify a structural cause for atrial fibrillation in elderly patients that is easily identified by transthoracic echocardiography. |
2,863 | Atrial pacing for the prevention and termination of atrial fibrillation. | Atrial fibrillation (AF) affects about 2% of the general population and 8%-11% of those older than 65 years. The demand for effective therapeutic strategies for AF is anticipated to increase substantially as the proportion of the elderly population increases. Atrioventricular nodal ablation accompanied by permanent pacemaker implantation is an established option in elderly patients with intractable arrhythmia and poor ventricular rate control. However, it renders most patients pacemaker dependent and does not eliminate symptoms associated with loss of atrial transport or reduce the risk of stroke. The considerable limitations of rhythm or rate control strategies prompted interest in preventative atrial pacing, which may reduce the incidence of AF by either eliminating the triggers and/or by modifying the substrate of AF. Atrial or dual-chamber pacing has been proven to prevent or delay progression to permanent AF in elderly patients with sinus node dysfunction as compared with ventricular pacing. Patients with advanced atrial conduction delay may benefit from atrial resynchronization pacing. There may be additional benefits associated with the use of particular sites of pacing, specific pacing algorithms designed to target potential triggers of AF, and pace-termination of atrial tachycardia. Preventive and antitachycardia pacing algorithms incorporated in implantable cardioverter-defibrillators and pacemakers are currently under investigation and may offer a valuable alternative to antiarrhythmic drug therapy in elderly patients with left ventricular dysfunction at high risk of proarrhythmia or worsening heart failure. The evolution of hybrid therapy, in which two or more different strategies are employed in the same patient, may be the most effective approach to management of AF. |
2,864 | Indications and nonindications for ablation of atrioventricular conduction in the elderly: is it sensible to destroy normal tissue? | Atrial fibrillation is common in later life. The goals of therapy are maintenance/restoration of sinus rhythm and control of ventricular rate when atrial fibrillation occurs. The only nonpharmacologic therapy of proven benefit is atrioventricular junction ablation and pacing, but this approach is irreversible and requires clear guidelines for patient selection. In paroxysmal atrial fibrillation, ablation and pacing carries a high risk of progression to permanent atrial fibrillation within 6 months but is indicated only when at least two appropriate drug strategies have failed. In persistent atrial fibrillation, ablation and pacing will inevitably result in permanent atrial fibrillation; this may influence the decision for pacemaker type and the timing of the procedure. In permanent atrial fibrillation, there is clear evidence for benefit, especially in those with reduced left ventricular function. In conclusion, ablation and pacing offers symptomatic and functional benefit to patients with drug-refractory atrial fibrillation. Timing of the intervention relates to response to other pharmacologic therapy. |
2,865 | Ventricular rate control in the elderly: is digoxin enough? | The ventricular response in untreated patients with atrial fibrillation often exceeds 120 beats/min at rest. Digoxin can slow this rate, but its efficacy during exertion may be limited. Alternatives, or additions, to digoxin therapy include the beta blockers and diltiazem or verapamil. This review discusses the role of digoxin in relation to these other drugs, with particular reference to the elderly population. |
2,866 | Left ventricular geometry immediately following defibrillation: shock-induced relaxation. | A previous two-dimensional (2D) ultrasound study suggested that there is relaxation of the myocardium after defibrillation. The 2D study could not measure activity occurring within the first 33 ms after the shock, a period that may be critical for discriminating between shock- and excitation-induced relaxation. The objective of our study was to determine the left ventricular (LV) geometry during the first 33 ms after defibrillation. Biphasic defibrillation shocks were delivered 5-50 s after the induction of ventricular fibrillation in each of the seven dogs. One-dimensional, short-axis ultrasound images of the LV cavity were acquired at a rate of 250 samples/s. The LV cavity diameter was computed from 32 ms before to 32 ms after the shock. Preshock and postshock percent changes in LV diameter were analyzed as a function of time with the use of regression analysis. The normalized mean pre- and postshock slopes (0.2 +/- 2.2 and 3.3 +/- 7.9% per 10 ms) were significantly different (P < 0.01). The postshock slope was positive (P < 0.005). Our results confirm that the bulk of the myocardium is relaxing immediately after defibrillation. |
2,867 | Surgical treatment of tachyarrhythmias due to postinfarction left ventricular aneurysm with endoaneurysmorrhaphy and cryoablation. | In this study, the efficacy of left ventricular (LV) endoaneurysmorrhaphy and cryoablation without intraoperative electrophysiologic mapping was evaluated in patients with postinfarction LV aneurysm and sustained ventricular tachycardia (VT).</AbstractText>A prospective study was performed on all patients operated with malignant VT in the presence of a resectable LV aneurysm between July 1990 and February 2001.</AbstractText>The study included 31 patients, 20 men and 11 women, with a mean age of 65.5 years (47-84). Monomorphic, polymorphic VT or ventricular fibrillation was present in all patients prospectively, and VT was incessant in 11. Twenty-six patients had an anterior, four patients had an inferior and one patient a posterolateral myocardial wall infarction. All patients had a well-limited ventricular aneurysm. Ten patients had three, eight patients two and 13 patients had single vessel coronary artery disease. Mean preoperative ejection fraction was 34.8 +/- 14.5% (8-62) and mean end-diastolic volume index was 141.5 +/- 51.8 ml/m(2) (57-288). Six patients had mitral regurgitation grade III or IV. All patients underwent extensive cryoablation at the transition zone of scar and viable tissue and LV remodelling with prosthetic patch in 26 patients. Associated procedures were CABG in 19 patients (61%) and mitral valve reconstruction in six patients (19%). Postoperative electrophysiologic study (EPS) revealed freedom from VT induction in 25 patients and inducible VT in five patients. One patient had inducible polymorphic VT. Five patients received an implantable cardioverter defibrillator (ICD) and three patients had a permanent pacemaker implanted. After a mean follow-up of 30 +/- 27 months (6-132) there was one arrhythmia-related death. There was one early hospital readmission for clinical VT and no need for late ICD implantation.</AbstractText>In patients suffering from ventricular arrhythmias in the presence of a complicated postinfarction LV aneurysm, combined 'blind' cryoablation and endoaneurysmorrhaphy offers excellent arrhythmia control and clinical and haemodynamic outcome.</AbstractText>Copyright 2002 Elsevier Science B.V.</CopyrightInformation> |
2,868 | Post-resuscitation right ventricular dysfunction: delineation and treatment with dobutamine. | Left ventricular dysfunction after resuscitation from cardiac arrest has been well described. Treatment with dobutamine improves post-resuscitation left ventricular function. Right ventricular function following resuscitation has not been investigated. The purposes of this study were to examine right ventricular function following resuscitation and determine whether dobutamine would improve post-resuscitation right ventricular function.</AbstractText>Right ventricular function was measured in 28 swine (29+/-1 kg) before and after resuscitation from 15 min of untreated ventricular fibrillation. Twelve animals received dobutamine at 10 mcg/kg/min while 16 animals served as untreated controls. Among controls, right ventricular dysfunction post-resuscitation was demonstrated by a decrease in right ventricular ejection fraction and an increase in right ventricular end-diastolic pressure. Among animals treated with dobutamine, there was a significant improvement in right ventricular function post-resuscitation compared to untreated controls.</AbstractText>This study establishes that right ventricular systolic and diastolic dysfunction does occur after prolonged cardiac arrest from ventricular fibrillation. Dobutamine can ameliorate post-resuscitation right ventricular dysfunction.</AbstractText>Copyright 2002 Elsevier Science Ireland Ltd.</CopyrightInformation> |
2,869 | Defibrillation threshold and cardiac responses using an external biphasic defibrillator with pediatric and adult adhesive patches in pediatric-sized piglets. | Before recommendations for using an automatic external defibrillator on pediatric patients can be made, a protocol for the energy of a biphasic waveform energy dosing needs to be determined that will allow ventricular defibrillation of 8 year olds while causing only a minimal amount of cardiac damage to infants. Pediatric- and adult-sized electrode patches were alternately applied to 10 isoflurane-anesthetized piglets weighing 3.8-20.1 kg to approximate the body weights of newborns to children < 8 years old. The defibrillation threshold (DFT) was determined for biphasic truncated exponential waveform shocks. Additional shocks, varying from the DFT to 360 Joules (J), were delivered during sinus rhythm or following 30 s of ventricular fibrillation (VF). The DFT was 2.4+/-0.81 and 2.1+/-0.65 J/kg for pediatric and adult patches, respectively (P = N.S.). The change in left ventricular (LV) dP/dt from baseline as a function of shock strength was significantly different at 1 and 10 s after shocks of increasing energy that were delivered in sinus rhythm, and 1, 10, 20, and 30 s after defibrillation shocks. There was no significant difference in LV dP/dt with increasing shock energy at 60 s with either patch size. The time to return of sinus rhythm, ST-segment deviation, and cardiac output were also not significantly different from baseline 60 s following shocks of up to 360 J delivered during sinus rhythm or VF with either patch. The same amount of energy delivered with a biphasic external defibrillator successfully defibrillated VF whether adult or pediatric patches were used. Cardiac rhythm and hemodynamic variables were unaltered at 60 s after shocks delivered at energies of up to 360 J. These data suggest that there is a substantial safety margin above a DFT strength shock for this biphasic waveform in piglets. |
2,870 | Impact of atrial fibrillation on mortality in patients with chronic heart failure. | Chronic heart failure and atrial fibrillation often occur together. The aim of the study is to review the available literature on the impact of atrial fibrillation on mortality in patients with heart failure. Using MEDLINE six full papers were identified. In the studies with severe heart failure atrial fibrillation did not emerge as an independent predictor of mortality beyond standard clinical variables. In contrast, atrial fibrillation was associated with increased mortality in case of mild-to-moderate heart failure. |
2,871 | [Proinflammatory cytokines (IL-6, TNF-alpha) and cardiac troponin I (cTnI) in serum of young people with ventricular arrhythmias]. | In the most cases the origin of ventricular arrhythmias is ischaemic, necrosis focus or presence of the connective tissue in cardiac muscle. The aim of the study was to evaluate troponin I (cTnI), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) vs in young subject with ventricular arrhythmias. Into the study group included young people without organic heart diseases, dyselectrolitemia, with normal ECG which has not elevated levels of C-reactive protein (55 persons). The control group consisted of 22 healthy persons. The values of cTnI were not increased. The TNF-alpha concentrations were elevated in persons with ventricular arrhythmias (92 +/- 232 pg/mL vs. 2 +/- 1 pg/mL, p < 0.001). The IL-6 concentrations were slightly elevated without statistical significance (1.5 +/- 4.5 pg/mL i 0.1 +/- 0.04 pg/mL, p = 0.06).</AbstractText>There was no evidence of myocardial injury in young people with ventricular arrhythmias (cTnI). We noted increase levels of proinflammatory cytokines. It might suggest that the background of ventricular arrhythmias is inflammation.</AbstractText> |
2,872 | Diastolic heart failure in the community: clinical profile, natural history, therapy, and impact of proposed diagnostic criteria. | Diastolic heart failure (DHF) has been broadly defined as "signs and symptoms of congestive heart failure (CHF) with normal/near normal systolic function." The clinical profile and natural history of the syndrome remain controversial. Furthermore, the frequency with which patients with CHF and normal ejection fraction (EF) fulfill recently proposed standardized diagnostic criteria for DHF is unclear. Our objective was to determine the clinical profile, Doppler echocardiographic features, current management, prognosis, and predictors of outcome of all patients with new onset CHF who had normal EF in Olmsted County, Minnesota, during 1996-1997. The frequency with which patients met recently proposed standardized criteria for diagnosis of DHF was assessed.</AbstractText>Using the resources of the Rochester Epidemiology Project, all residents of Olmsted County, Minnesota, with a new diagnosis of CHF in 1996-1997, an ejection fraction >45%, and no valve disease (n = 83) were identified.</AbstractText>Patients were elderly (79 +/- 13 yr), predominantly female (76%), and had hypertension and/or coronary artery disease (85%). New-onset atrial fibrillation, ischemia, and medical comorbidities were frequently present at diagnosis. Although most patients (81%) met criteria for "probable DHF" by recently proposed clinical criteria, only half of patients met European criteria in which evidence of abnormal function/filling is required. The 1-, 2-, and 3-year mortality rates were 29%, 39%, and 60%, respectively. Angiotensin-converting enzyme inhibition (P =.0008) and beta-blocker (P =.02) therapy were independently associated with improved survival.</AbstractText>This population-based study provides a comprehensive clinical profile, current management, prognosis, and predictors of outcome of patients with new onset CHF who had normal ejection fraction.</AbstractText> |
2,873 | Clinical use of AcuNav diagnostic ultrasound catheter imaging during left heart radiofrequency ablation and transcatheter closure procedures. | AcuNav ultrasound catheter (UC) (10F, 5.5-10 MHz) has unique advantages for left heart imaging with its 4-way tip flexible maneuverability, maximal 16-cm intracardiac imaging depth, and Doppler and color flow imaging capability.</AbstractText>We assessed the initial use of this UC in 40 consecutive patients (34 men; age 53 +/- 11 years old). All patients were also undergoing transseptal catheterization for percutaneous catheter mapping and ablation of either left atrium (focal initiated atrial arrhythmia/fibrillation, n = 32) or left ventricle (ventricular tachycardia, n = 4), or transcatheter atrial septal defect closure (n = 4) procedures. During each procedure, the UC was placed in the right atrium, superior vena cava, or right ventricular inflow/outflow tract.</AbstractText>In all patients, UC successfully guided transseptal catheterization and provided imaging of normal or aberrant anatomy of the right/left atrial (interatrial septum, fossa ovalis, appendages, 4 pulmonary vein ostia) and right/left ventricular (valves and papillary muscles) structures. UC was important in early identification procedure complications, including pericardial effusion (n = 2, detected before systematic hemodynamic deterioration) and thrombus formation on sheaths deployed in the right atrium (n = 9) and left atrium (n = 2, early elimination with management of the sheath). With Doppler and color flow imaging, UC provided effective monitoring of increased flow velocity of all ablated pulmonary vein ostia and detection of patent foramen ovale (n = 6) or residual trivial/small atrial septal defect posttransseptal catheterization (n = 2). UC was also used to successfully image and guide transcatheter closure of atrial septal defect with positioning of the cardioseal septal occluder (Nitinol Medical Technologies Inc, Boston, Mass) and color Doppler imaging of no significant residual shunt.</AbstractText>AcuNav UC with Doppler and color flow imaging has significant use, especially during left heart ablation. Uses include guidance of transseptal and mapping/ablation catheters and closure devices, and prompt diagnosis of cardiac complications.</AbstractText> |
2,874 | Fractionated-clamping for thoracoabdominal aortic aneurysm repair: a modified Crawford technique. | To apply fractionated-clamping for repair of thoracoabdominal aortic aneurysm (TAA), and evaluate its effects in decreasing surgical mortality and severe complications, such as renal failure and paraplegia, a modified crawford procedure were prospectively evaluated.</AbstractText>Using modified shunting and cross-clamping techniques, modified Crawford repair in 13 thoracoabdominal aorta patients were performed in the Vascular Division at Peking Union Medical College Hospital. TAA Crawford classification: 1 type I, 2 type II, 2 type III and 3 type IV TAA. Debakey classification: 1 type I, 4 type III (including 2 ruptured aneurysms), and 1 aortic coarctation.</AbstractText>Thirteen procedures were performed successfully. One died of ventricular fibrillation just before completing the operation. Surgical mortality rate was 7.7% (1/13). Postoperative complications included 1 acute necrotic pancreatitis, 1 ARDS, 1 paraplegia, 1 acute renal failure, and 2 thoracic cavity bleeding. Total complication rate was 53.8% (7/13).</AbstractText>Fractionated-clamping in thoracoabdominal aortic aneurysm repair is our modified Crawford procedure and aortic bypass. Clinical results demonstrate that our procedure decreased surgical mortality and major complication rate, and also alleviated viscera ischemic injury. Fractionated-clamping in aorta replacement is a practical procedure for TAA repair under general anesthesia at normal temperature.</AbstractText> |
2,875 | Anti-arrhythmic peptide N-3-(4-hydroxyphenyl)propionyl Pro-Hyp-Gly-Ala-Gly-OH reduces dispersion of action potential duration during ischemia/reperfusion in rabbit hearts. | During ischemia, cardiac gap junctions close and neighboring cells uncouple. This leads to slow conduction, increased dispersion of APD90 (duration from action potential beginning to 90% of repolarization), nonuniform anisotropy, and unidirectional conduction block, all of which favor the induction of reentry arrhythmias. It has been suggested that anti-arrhythmic peptides increase gap junction conductance during states of reduced coupling. The aim of this study was to test the effect of the anti-arrhythmic peptide N-3-(4-hydroxyphenyl)propionyl Pro-Hyp-Gly-Ala-Gly-OH (HP-5) (10(-10) ) on dispersion of epicardial APD90 during both normokalemic and hypokalemic ischemia/reperfusion in isolated perfused rabbit hearts. HP-5 did not affect average APD90, heart rate, left ventricular contractility (LVP dP/dtmax), or mean coronary flow. HP-5 significantly reduced the epicardial APD dispersion during hypokalemic ischemia (HP-5 treated: 24.1 +/- 3.4 ms, untreated: 33.9 +/- 3.1 ms, p < 0.05 versus untreated) and during normokalemic reperfusion but not during normokalemic ischemia or control conditions. In addition, among untreated hearts subjected to hypokalemic ischemia/reperfusion, seven of 10 developed ventricular fibrillation, whereas only three of nine hearts perfused with HP-5 developed ventricular fibrillation. These results show that HP-5 is able to reduce APD90 dispersion during hypokalemic ischemia in rabbit hearts. |
2,876 | Arrhythmias in Patients with Heart Failure. | Both atrial and ventricular arrhythmias are very common in patients with congestive heart failure, and their presence is associated with symptoms, significant morbidity, and mortality. Studies have attempted to determine the prognostic significance of atrial and ventricular arrhythmias in patients with heart failure. Whether atrial fibrillation is an independent risk factor of mortality remains controversial. The presence of ventricular arrhythmias in patients with ischemic cardiomyopathy identifies patients at high risk for sudden death. However, in patients with nonischemic cardiomyopathy there is not a strong correlation between ventricular arrhythmias and increased risk for sudden death. Multiple trials using antiarrhythmic drugs, pharmacologic therapy, and implantable cardioverter defibrillators have been performed in an attempt to improve survival in patients 1) post-myocardial infarction; 2) with congestive heart failure, with and without nonsustained ventricular tachycardia; and 3) with sustained ventricular tachycardia and those who have survived an out-of-hospital cardiac arrest. The purpose of this article is to present an overview of arrhythmias in patients with heart failure and discuss the prevalence, prognostic significance, complications, mechanisms, and trials that have formed the current therapies presently used. |
2,877 | Hypertrophic Cardiomyopathy. | When an individual is diagnosed with hypertrophic cardiomyopathy (HCM), all relatives potentially affected by Mendelian autosomal-dominant inheritance should be evaluated with an electrocardiogram (ECG) and echocardiogram. Genetic testing should be considered in high-risk mutations where there are diagnostic uncertainties. Symptom relief depends on beta-blockers as first-line therapy. If the disease is nonobstructive, then calcium channel blockers can be added or used alone. If there is a significant left ventricular outflow tract (LVOT) gradient then disopyramide can be used, ideally in combination with a beta-blocker. Verapamil should be used with care due to potential exacerbation of the LVOT gradient. Nonmedical therapy for obstructive disease consists of surgical myectomy, alcohol septal ablation, or dual-chamber pacing. Surgery is the gold standard, although in experienced hands and directed appropriately, septal ablation achieves good results. Pacing is generally less effective. The development of atrial fibrillation (AF) or left atrial enlargement carries a significant risk of thromboembolism. All patients should be closely observed for AF and thromboembolic risk, and the threshold for initiation of anticoagulation should be low in patients with sustained palpitations, atrial enlargement, and nonsustained supraventricular arrhythmia on Holter. All patients with HCM should be assessed for their risk of sudden death regardless of severity of symptoms or morphology. The factors predictive of risk are 1) previous cardiac arrest; 2) unexplained syncope; 3) family history of premature sudden death; 4) abnormal blood pressure response to exercise; 5) nonsustained ventricular tachycardia; and 6) severe left ventricular hypertrophy >/= 30 mm. |
2,878 | Inappropriate high-rate ventricular pacing in a patient with a defibrillator. | We describe a patient who presented with high rate ventricular pacing secondary to dysfunction of his implantable cardioverter defibrillator (ICD). The device was also unable to communicate with the programmer and unable to treat ventricular fibrillation. Immediate disconnection of the ICD from the leads was the only effective recourse. Subsequent detailed technical analysis of the device revealed a different electrical circuit problem from that found in typical cases of runaway pacing. To our knowledge this is the first description of a malfunction of precisely this nature. |
2,879 | [Atrial fibrillation and heart failure: cause or effect?]. | The association between atrial fibrillation and heart failure is well documented. Heart failure is one of the established predisposing conditions for the development of atrial fibrillation; conversely, heart failure is a common condition in patients with atrial fibrillation. In patients with heart failure the atrial electrophysiologic properties might be modified by hemodynamic overloading and neurohumoral activation. Atrial fibrillation promotes heart failure with multiple mechanisms including uncontrolled heart rate, loss of atrioventricular synchrony, irregularity in the ventricular rhythm, valvular regurgitation and neurohormonal effects. Treatment includes correction of neurohumoral activation, prevention of thromboembolism, maintenance of sinus rhythm, and pharmacologic and interventional control of ventricular rate. The results of recent trials (PIAF-Pharmacological Intervention in Atrial Fibrillation, RACE-RAte Control versus Electrical cardioversion for persistent atrial fibrillation, AFFIRM-Atrial Fibrillation Follow-up Investigation of Rhythm Management) suggest that a rate control strategy can be better than rhythm control, particularly in patients at high risk of relapse, like those with left ventricular dysfunction. |
2,880 | [Refractory heart failure. Multisite stimulation]. | The pathophysiological background of cardiac resynchronization therapy is represented by the intraventricular conduction delay such as left bundle branch block, present in about one third of patients with dilated cardiomyopathy. Intraventricular conduction block, with or without atrioventricular delay, adversely influences ventricular function due to unsynchronized contraction and is associated with a poor prognosis. Contractile dyssynchrony and abnormal atrioventricular delay can be corrected by non-conventional stimulation modalities such as left ventricular pacing or biventricular pacing associated with preexcitation to restore the physiological atrioventricular timing. Over the last decade several studies have reported the short- or long-term favorable effects of resynchronization therapy on the left ventricular function and remodeling, the quality of life, the functional capacity, the adrenergic activity, and the reduced rehospitalization rate. The most significant results have been reported in patients with a QRS duration > or = 150 ms, while the InSync Italian Registry has shown improvement even in patients with a QRS duration < 150 ms as well as in patients with atrial fibrillation. On the basis of such data it may be argued that the activation sequence of the different walls of the left ventricle is likely more important than the QRS duration. Inclusion criteria commonly used in the published or ongoing trials are: moderate to severe congestive heart failure (NYHA functional class III-IV) on optimized pharmacological treatment; left ventricular ejection fraction < or = 35%; left ventricular diastolic diameter > 60 mm; end-diastolic mitral regurgitation; no need of conventional pacing. While with regard to the surrogate endpoints the results of published trials are very encouraging, we do not yet know whether resynchronization therapy prolongs the life expectancy of patients with heart failure. Studies able to provide important answers to these problems are near completion. In the meanwhile, in agreement with the guidelines of the European Society of Cardiology, it seems prudent to employ such a therapy only in case of patients satisfying the above-mentioned criteria. |
2,881 | Postoperative oral amiodarone as prophylaxis against atrial fibrillation after coronary artery surgery. | To assess the prophylactic effect of postoperative oral amiodarone on the incidence and severity of atrial fibrillation (AF) after coronary artery surgery.</AbstractText>Prospective, randomized, blinded, controlled study.</AbstractText>University hospital.</AbstractText>Patients who had coronary artery surgery (n = 200).</AbstractText>Patients in group 1 (n = 100) received oral amiodarone, 15 mg/kg, 4 hours after arrival in the intensive care unit, followed by 7 mg/kg/d until hospital discharge. Patients in group 2 (n = 100) received placebo.</AbstractText>Incidence, duration, and recurrence of new episodes of AF and maximal ventricular rate response were recorded from day 0 until hospital discharge. Side effects related to amiodarone and complications induced by new-onset AF were noted. The incidence of new-onset AF (12% v 25%) and maximal ventricular rate response (120 +/- 21 beats/min v 135 +/- 24 beats/min) were significantly lower in the amiodarone group. There were no side effects related to the administration of amiodarone. The incidence of complications induced by AF was comparable between the 2 groups.</AbstractText>Postoperative prophylactic oral amiodarone after coronary artery surgery is safe and effective in reducing the incidence of new-onset AF and maximal ventricular rate response.</AbstractText>Copyright 2002, Elsevier Science (USA). All rights reserved.</CopyrightInformation> |
2,882 | Transthoracic defibrillation of short-lasting ventricular fibrillation: a randomised trial for comparison of the efficacy of low-energy biphasic rectilinear and monophasic damped sine shocks. | Biphasic rectilinear shocks are more effective than monophasic shocks for transthoracic atrial defibrillation and for ventricular arrhythmias during electrophysiological testing. We undertook the present study to compare the efficacy of 100 J rectilinear biphasic waveform shocks with 150 J monophasic damped sine waveform shocks for transthoracic defibrillation of true ventricular fibrillation during defibrillation threshold testing (DFT). The second aim of the study was to analyse the influence of patch positions on the efficacy of defibrillation.</AbstractText>50 episodes of 14 patients (age ranging from 37 to 82 years) who underwent DFT testing were randomised for back-up shocks with either a sequence of 100 and 200 J biphasic waveform, or a sequence of 150 and 360 J conventional monophasic shocks. A binary search protocol was used at implantation and before hospital discharge. Patients were also randomised to an anteroposterior position versus a right-anterior-apical position. A crossover was performed between implantation and pre-hospital discharge for biphasic versus monophasic sequence as well as for the 2 different positions.</AbstractText>After failed internal shocks, 27 episodes were treated with biphasic, and 23 with monophasic shocks. The first attempt by the external device did not terminate II episodes (2 biphasic, 9 monophasic). The first shock efficacy was significantly greater with biphasic than with monophasic shocks (p < 0.02). The overall success rate was 93% with biphasic shocks and 64% with monophasic shocks. In multivariate regression analysis including patch position, arrhythmia duration, type of waveform, testing order and session, only waveform was associated with successful defibrillation (p < 0.02).</AbstractText>For transthoracic defibrillation of ventricular fibrillation, low-energy rectilinear biphasic shocks are more effective than monophasic shocks. The position of the defibrillation shock pads has no influence on the biphasic shock efficacy, but anteroposterior pad position is more effective using monophasic shocks.</AbstractText> |
2,883 | New insights into the mechanisms and management of atrial fibrillation. | Atrial fibrillation (AF) is a common contributor to cardiovascular morbidity and mortality. Two generally acceptable strategies exist for long-term AF management, with ongoing studies comparing the overall mortality associated with each. One strategy aims to maintain sinus rhythm, with antiarrhythmic agents if necessary, thereby preserving physiological cardiac electrical function but exposing the patient to the potential side effects of potent drugs. The second approach is to control the ventricular rate and prevent thromboembolic complications with anticoagulants, leaving the patient with AF. Both beta-blocking agents and calcium antagonists are more effective than digoxin in achieving rate control. Several nonpharmacological therapies including catheter ablation, implantable devices and surgical interventions show promise for rate control and maintenance of sinus rhythm. This paper provides an overview of new developments in pharmacological and nonpharmacological therapy. Key features of recently published clinical guidelines, including a unified classification scheme for AF and issues relating to rate control and maintenance of sinus rhythm, are considered. In addition, preliminary results from the recently presented AFFIRM study, the largest AF trial to date, are summarized. Finally, we discuss recent insights into the basic mechanisms underlying AF that have potentially significant clinical implications. |
2,884 | Delays in defibrillation: influence of different monitoring techniques. | Rapid defibrillation is the most important intervention required for a patient in cardiac arrest due to ventricular fibrillation or ventricular tachycardia. Isolated case reports of spurious asystole may have seen a change in practice, moving away from monitoring through defibrillator paddles and gel pads in favour of attaching electrocardiograph (ECG) leads for the initial monitoring of a collapsed patient. We surveyed current preferences for initial monitoring and estimated the difference in time taken to deliver the first shock with the following three monitoring techniques: defibrillator paddles and gel pads, ECG leads and hands-free adhesive pads.</AbstractText>Sixty Advanced Life Support (ALS) course directors, selected at random, were questioned to establish their current practice. Twenty ALS providers received 5 min revision in the three techniques for the initial monitoring of a collapsed patient and were then randomly tested to measure the time from confirmation of arrest to the first shock.</AbstractText>Forty-two directors indicated their preferred methods for initial monitoring as 74% leads, 21% paddles and 5% hands-free adhesive pads. Before testing, 10 providers preferred paddles and 10 preferred leads. Monitoring through leads 54 (range 49-65) s was significantly slower than paddles 28 (24-31) s, P < 0.01 and adhesive pads 23 (19-27) s, P < 0.01. There was no significant difference in the time taken between paddles and adhesive pads.</AbstractText>The current practice of monitoring through leads delays the time to deliver the first shock. We recommend that initial monitoring through leads be discontinued in favour of hands-free adhesive pads or defibrillator paddles/gel pads.</AbstractText> |
2,885 | Adult cardiac arrest in general practice. | Out of hospital cardiac arrest victims contribute significantly to adult mortality figures but are encountered infrequently by most general practitioners and their staff. A number of scientific organisations produce guidelines for the basic and advanced management of cardiac arrest.</AbstractText>To review the management principles for basic and advanced adult cardiac life support measures for cardiac arrest.</AbstractText>General practitioners are required to manage cardiac arrest victims infrequently. The initiation of bystander cardiopulmonary resuscitation and the rapid defibrillation of suitable cardiac rhythms determine a favourable outcome. All staff working at a surgery must be skilled in basic life support. The GP needs an understanding of advanced life support principles.</AbstractText> |
2,886 | Halothane, isoflurane, and fentanyl increase the minimally effective defibrillation threshold of an implantable cardioverter defibrillator: first report in humans. | Placing an implantable cardioverter defibrillator (ICD) involves the induction of ventricular fibrillation, whereupon the minimally effective defibrillation energy threshold (DFT) is determined. We evaluated the effects of 0.7% halothane, 1% isoflurane, or 1.5 micro g/kg of IV fentanyl during N(2)O/oxygen-based general anesthesia (GA) or those of subcutaneous 1.5% lidocaine plus IV 0.35 mg/kg of propofol on the DFT during ICD implantation in humans (n = 20 per group). Thirty minutes after the first set of DFT measurements under such conditions, the inhaled anesthetics were withdrawn, and all three GA groups received fentanyl 1 microg/kg IV (second set). A third set was taken 30 min later, before the GA patients awakened and when only N(2)O/oxygen was delivered for GA. The lidocaine plus propofol patients were given the same IV propofol bolus 1 min before each fibrillation/defibrillation trial and at the same time points as the three GA groups. The first DFTs were 16.1 +/- 2.2 J (halothane), 17.7 +/- 2.7 J (isoflurane), 16.4 +/- 2.9 J (fentanyl), and 12.9 +/- 3.8 J (lidocaine plus propofol) (P = 0.01). The second set of DFTs were significantly lower than the first sets for the halothane (P = 0.01) and isoflurane (P = 0.02), but not the fentanyl or lidocaine plus propofol, regimens. The third DFTs were significantly (P < 0.01) lower than the first ones for the three GA groups, but not for the lidocaine plus propofol patients. Thus, halothane, isoflurane, and fentanyl increased DFT values during ICD implantation in humans, whereas lidocaine plus intermittent small-dose IV propofol minimized these thresholds.</AbstractText>Halothane, isoflurane, and IV fentanyl added to N(2)O/oxygen-based general anesthesia similarly increase minimal defibrillation threshold energy requirements (DFT) during cardioverter defibrillator implantation in humans. Subcutaneous lidocaine plus intermittent small-dose IV propofol minimizes DFT compared with these general anesthetics while providing equal patient satisfaction.</AbstractText> |
2,887 | Off-pump multivessel coronary artery surgery in high-risk patients. | Coronary artery bypass surgery on cardiopulmonary bypass is associated with significant morbidity and mortality, which may be more marked in high-risk patients. We evaluated our results of off-pump coronary artery bypass (OPCAB) in high-risk patients with multivessel coronary artery disease and compared them with results in similar patients who underwent operation on cardiopulmonary bypass.</AbstractText>A total of 1,075 patients who underwent OPCAB between October 1996 and June 2001 and who had one or more of the following risk factors were included in the study: poor left ventricular function (EF < or = 30%), advanced age (> 70 years), left main stenosis, acute myocardial infarction, and redo coronary artery surgery. These patients were compared with 2,312 similar patients who underwent coronary artery bypass grafting on cardiopulmonary bypass during the same period. Preoperative risk factors, intraoperative variables, and postoperative results were analyzed and compared between two groups.</AbstractText>The average number of grafts was 3.0 +/- 0.4 and 3.2 +/- 0.3 in the off-pump (OPCAB) and on-pump (CCAB) groups, respectively. Hospital mortality was 3.2% and 4.5% in OPCAB and CCAB groups respectively (p = 0.109). Perioperative myocardial infarction, requirement of inotropic agents, stroke, and renal dysfunction were comparable in two groups. Intubation time (19 +/- 5 vs 24 +/- 6 hours, p < 0.001), mean blood loss (362 +/- 53 vs 580 +/- 66 mL, p < 0.001), atrial fibrillation (14.3 vs 19.7%, p < 0.001), and prolonged ventilation (4.6 vs 7.6%, p = 0.002) were less in OPCAB group. Intensive care unit stay (20 +/- 8 hours) and hospital stay (6 +/- 3 days) were significantly less in the OPCAB group (p < 0.001).</AbstractText>Off-pump coronary artery surgery can be safely performed in high-risk patients with multivessel coronary artery disease. Operative mortality is comparable to that associated with on-pump surgery, and avoidance of cardiopulmonary bypass is associated with reduced postoperative morbidity in these patients.</AbstractText> |
2,888 | Surgical revascularization in patients with poor left ventricular function: on- or off-pump? | Patients with left ventricular dysfunction and low ejection fraction (EF) are at high-risk of complication and mortality after coronary artery bypass grafting (CABG). The potential success of off-pump CABG in this high-risk population has yet to be determined. The purpose of this study is to compare the outcome of off-pump coronary artery bypass (OPCAB) and conventional coronary artery bypass (CCAB) in patients with poor left ventricular function, all from a single institution.</AbstractText>Data on patient demographics, preoperative risk factors, operative and postoperative outcomes were collected retrospectively on all patients having undergone isolated CABG between January 1, 1998, and October 31, 2001.</AbstractText>A total of 77 patients (31 OPCAB/46 CCAB) were identified as having an ejection fraction (EF) of < or = 0.35. Of these, 52 had EF < or = 0.30 (21 OPCAB/31 CCAB) and 31 patients had EF < or = 0.25 (10 OPCAB/21 CCAB). Operative mortality was 3.2% after the OPCAB procedure versus 10.9% for the CCAB (p = 0.39). Use of intraaortic balloon pump (6.5%) was rarely required. The OPCAB procedure resulted in significantly less requirement for blood transfusions (p < 0.05), fewer distal anastomoses per patient (p < 0.01), and a higher incidence of atrial fibrillation (p < 0.05) compared with CCAB.</AbstractText>Patients with poor left ventricular function may undergo surgical revascularization using off-pump technique with relatively good results and low mortality levels. The lower number of grafts performed on the off-pump procedure did not seem to affect clinical outcomes.</AbstractText> |
2,889 | Left atrial dimensions determined by M-mode echocardiography in black and white older (> or =65 years) adults (The Cardiovascular Health Study). | Stroke and atrial fibrillation are common and serious illnesses in the elderly, the risks of which are substantially increased by left atrial (LA) enlargement. Despite growing recognition of the importance of LA enlargement, the distribution and correlates of LA dimension in the elderly have not been well defined. A total of 3,882 women and men aged >65 years were studied. Increased LA dimension was independently associated with increased weight, mitral annular calcium, regional wall motion abnormalities, mitral early peak inflow velocity, and left ventricular (LV) fractional shortening. Increased LA dimension was negatively associated with aortic leaflet thickening. The relation with LV fractional shortening was curvilinear with a nadir at 35% to 40%. LA dimension in black men was approximately 1.9 mm less than in white men in multivariate analyses. Adjustment for spirometric lung volumes and chest dimensions appeared to diminish the race-LA dimension relation. Thus, LA dimension is strongly associated with weight and with several echocardiographic valvular abnormalities; its relation with LV fractional shortening is U-shaped with a nadir at the borderline of LV functional impairment. |
2,890 | Cumulative effect of complete left bundle-branch block and chronic atrial fibrillation on 1-year mortality and hospitalization in patients with congestive heart failure. A report from the Italian network on congestive heart failure (in-CHF database). | Many clinical variables have been proposed as prognostic factors in patients with congestive heart failure. Among these, complete left bundle-branch block and atrial fibrillation are known to impair significantly left ventricular performance in patients with congestive heart failure. However, their combined effect on mortality has been poorly investigated. The aim of this study was to determine whether left bundle-branch block associated with atrial fibrillation had an independent, cumulative effect on mortality for congestive heart failure.</AbstractText>We analysed the Italian Network on congestive heart failure (IN-CHF) Registry that was established by the Italian Association of Hospital Cardiologists in 1995. One-year follow-up data were available for 5517 patients. Complete left bundle-branch block and atrial fibrillation were associated in 185 (3.3%) patients. In this population the cause of congestive heart failure was dilated cardiomyopathy (38.4%), ischaemic heart disease (35.1%), hypertensive heart disease (17.3%), and other aetiologies (9.2%). This combination of electrical defects was associated with an increased 1-year mortality from any cause (hazard ratio, HR: 1.88; 95% CI 1.37-2.57) and sudden death (HR: 1.89; 95% CI 1.17-3.03) and 1-year hospitalization rate (HR: 1.83; 95% CI 1.26-2.67).</AbstractText>In patients with congestive heart failure, the contemporary presence of left bundle-branch block and atrial fibrillation was associated with a significant increase in mortality. This synergistic effect remained significant after adjusting for clinical variables usually associated with advanced heart failure. We can conclude that this combination of electrical disturbances identifies a congestive heart failure specific population with a high risk of mortality.</AbstractText>Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved</CopyrightInformation> |
2,891 | Hypothermia and neurologic outcome in patients following cardiac arrest: should we be hot to cool off our patients? | Hypothermia as a protectant of neurologic function in the treatment of cardiac arrest patients, although not a new concept, is now supported by two recent randomized, prospective clinical trials. The basic science research in support of the effects of hypothermia at the cellular and animal levels is extensive. The process of cooling for cerebral protection holds potential promise for human resuscitation efforts in multiple realms. It appears that, at least, those patients who suffer a witnessed cardiac arrest with ventricular fibrillation and early restoration of spontaneous circulation, such as those who were included in the European and Australian trials (discussed here), should be considered for hypothermic therapy. |
2,892 | [Cardiac resynchronization therapy by biventricular pacing. How many patients with left ventricular dysfunction are eligible?]. | Cardiac resynchronization therapy by multisite biventricular pacing presents an additive therapeutic option in the treatment of severe congestive heart failure. The objective of the study was to evaluate how many patients with left ventricular dysfunction may potentially benefit from this therapy.</AbstractText>A total of 975 patients were screened for the prevalence of left ventricular dysfunction. Patients with a left ventricular ejection fraction (LVEF) <45 % were included into the investigation. Potential benefit of biventricular pacing was presumed in the presence of: LVEF < 35 %, severe heart failure (NHYA class III or IV), intrinsic left bundle branch block pattern with QRS interval > 150 ms and the absence of atrial fibrillation in the last 3 months before study inclusion.</AbstractText>In 203 patients (168 male, 35 female, mean age: 64 +/- 11) an LVEF <45 % was found. A total of 12 of these patients (6 %) or 12 of 113 patients (11 %) with an LVEF <35 % were identified as appropiate candidates for biventricular resynchronization therapy.</AbstractText>Cardiac biventricular pacing currently serves as a therapeutic option for a relatively small subgroup of patients with left ventricular dysfunction. Focusing on estimations that the incidence of heart failure in Germany amounts to more than 100.000 cases per year our results suggest that after all more than 6.000 patients per year may potentially benefit from electric resynchronization therapy. This number may increase substantially if prospective studies can prove that patients with heart failure and atrial fibrillation or left ventricular conduction delay due to univentricular pacing also benefit from cardiac resynchronization therapy.</AbstractText> |
2,893 | New approaches to atrial fibrillation management: a critical review of a rapidly evolving field. | Atrial fibrillation (AF) is the most common cardiac arrhythmia, the prevalence of which is increasing with the aging of the population. Because of its clinical importance and the lack of highly satisfactory management approaches, AF is the subject of active clinical and research efforts. This paper reviews recent and on-going developments in pharmacological and non-drug management of AF. The ideal therapeutic goal for AF is the production and maintenance of sinus rhythm. Comparative studies suggest that available class I and III drugs have comparable and modest efficacy for sinus rhythm maintenance. Amiodarone, with actions of all antiarrhythmic classes, has recently been shown to have clearly superior efficacy compared with other available drugs. Newer agents are in development, but their advantages are as yet unclear and appear limited. A potentially interesting approach is the prescription of drugs upon the occurrence of an attack, rather than on a continuous basis. Recent insights into AF mechanisms may permit therapy to prevent development of the AF substrate. An alternative to sinus rhythm maintenance is a rate control approach, with no attempt to prevent AF. Drugs to effect rate control include digitalis, beta-blockers and calcium channel antagonists. Digitalis has limited value for control of exercise heart rate and for paroxysmal AF, but is particularly well suited for patients with concomitant AF and congestive heart failure. AV-nodal ablation and pacing is an effective alternative for rate control but leaves the patient pacemaker dependent. The relative merits of rate versus rhythm control are being evaluated in ongoing trials, preliminary results of which indicate no statistically significant differences in primary endpoints but highlight the risks of rhythm control therapy. In patients requiring pacemakers, physiological pacing (dual chamber devices or atrial pacing) has an advantage over purely ventricular pacemakers in AF prevention. Newer pacing modalities that produce more synchronised atrial activation, as well as pacemakers that prevent excessive atrial rate swings, show promise in AF prevention and may soon see wider use. The usefulness of automatic atrial defibrillators is presently limited by discomfort during shocks. Targeted destruction of pulmonary vein foci by radiofrequency catheter ablation suppresses paroxysmal AF. Efficacy in persistent AF is lower and still under study. Problems include potential recurrence in other veins and a small but nontrivial risk of pulmonary vein stenosis. Surgical division of the atria into zones with limited electrical connection, the MAZE procedure, is highly effective in AF prevention but is a major intervention that is not applicable to most patients. In conclusion, significant advances are being made in the management of patients with AF but much more work remains to be done. |
2,894 | [Effect of diabetes mellitus in recovery and maintenance of sinus rhythm in patients with persistent atrial fibrillation]. | Diabetes mellitus is frequently accompanied by cardiac rhythm disorders. On the other hand, atrial fibrillation is the most frequent cardiac arrhythmia in adult population [1, 2]. According to some of the large epidemiological studies diabetes mellitus is among independent risk factors for development and persistence of atrial fibrillation [3]. Both diabetes mellitus and atrial fibrillation independently increase the risk of thromboembolism, especially of stroke [3-5]. It is obvious that rhythm control, i.e. restoration and maintenance of sinus rhythm, may be essential for prevention of thromboembolism in these patients.</AbstractText>The aim of this study is to analyse the impact of diabetes mellitus on rhythm control in patients with persistent atrial fibrillation.</AbstractText>We analysed the impact of diabetes mellitus and other clinical and echocardiographic parameters (age, gender, current arrhythmia duration, presence of previous episodes of persistent atrial fibrillation, cardiac and/or noncardiac diseases, left atrial diameter and left ventricular ejection fraction) on outcome of attempted cardioversion in patients with persistent atrial fibrillation admitted to Cardiologic Department of the Institute of Cardiovascular Diseases, Clinical Centre of Serbia, between January 1992 and December 1999. We also analysed retrospectively the impact of diabetes mellitus and other parameters listed above on the presence of previous episodes of atrial fibrillation in our patients, that at our opinion reflected the possibilities of sinus rhythm maintenance in these patients. All continuous parameters were expressed as mean value and standard deviation. Statistical significance of differences between variables was examined using Chi-square test. For identification of independent predictors of examined outcomes we used multiple logistic regression model with 95% of confidence interval. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) programme.</AbstractText>Of 378 patients with currently persistent atrial fibrillation, aged mean 53.98 +/- 11.69 years, there were 266 (70.4%) men. Diabetes mellitus was previously diagnosed in 27 (7.1%) patients, cardiac diseases in 223 (59.0%), noncardiac diseases in 47 (12.4%) and 140 (37.0%) patients had "lone" atrial fibrillation. Left atrial enlargement was noted in 224 (59.3%) patients, and reduced left ventricular ejection fraction in 82 (21.7%). Atrial fibrillation lasted 48 hours to 9 years, mean 8.5 +/- 18.14 months before cardioversion. While 43 patients had previous episodes of persistent AF for last 1-30 years, mean 10.5 +/- 7.3,335 patients never experienced AF before. There was a statistically significant difference in percent of diabetic patients (18.6%/43 vs. 5.7%/335, value of Chi-square test = 7.759, p < 0.01) in these two groups. We analysed the impact of diabetes mellitus on outcome of attempted cardioversion and on presence of previous episodes of AF reflecting the success in maintaining sinus rhythm. Multiple logistic regression models for all of 378 patients, with dependent variable being present in previous recurrent atrial fibrillations and independent variables of clinical and echocardiographic parameters as listed, identified diabetes mellitus to be an independent predictor of repeated atrial fibrillations with relative risk of 4.6 (CI 95%). When dependent variable in the same model was outcome of cardioversion (sinus rhythm is restored in 281/378 patients--74%) diabetes mellitus was not among independent predictors of successful cardioversion.</AbstractText>The relationship between atrial fibrillation and diabetes mellitus is not completely understood, including the impact of known complications of diabetes mellitus on electrophysiological properties of atrial myocardium and development of atrial fibrillation [6]. Besides being the independent risk factor for occurrence of atrial fibrillation, diabetes mellitus, according to our results, appears to influence the possibilities of maintaining sinus rhythm after cardioversion of permanent atrial fibrillation in diabetic patients. We found that patients with diabetes mellitus and persistent atrial fibrillation may be successfully converted to sinus rhythm like any other group of patients, but the presence of diabetes mellitus increases the risk of arrhythmia recurrence for 4.6 times compared to patients without diabetes mellitus. Obviously, diabetic patients need to be treated with more efficacious antiarrhythmics from the very beginning, including amiodarone, which successfully prevents recurrent atrial fibrillation in the majority of patients [7, 8].</AbstractText>We concluded that diabetes mellitus independently predicts the presence of recurrent atrial fibrillation but does not influence the possibility of sinus rhythm restoration. The relationship between atrial fibrillation and diabetes mellitus needs further investigation.</AbstractText> |
2,895 | Ventricular fibrillation during acute coronary occlusion is related to the dilation of the ischemic region. | Myocardial stretch induces several electrophysiological changes and arrhythmias, but little is known on its possible role in triggering ventricular fibrillation (VF) during acute coronary occlusion. In thiopental-anesthetized, open-chest pigs submitted to a 40-min ligation of the left anterior descending coronary artery, the association between the early increase in end-diastolic length (measured by means of ultrasonic crystals) in the ischemic region and subsequent VF was analyzed. Animals received no treatment (n = 35) or intravenous nitroglycerin (2.5 microg/kg/min for 20 min, starting 10 min after coronary occlusion, n = 8) or Gd(3+) (80 microM/kg for 35 min, starting 5 min before occlusion, n = 15). Twenty-four animals (41 %) had VF, 16 to 39 min after coronary occlusion. The magnitude of ischemic dilation and the incidence of VF were similar among groups. End-diastolic length in the ischemic region 15 min after coronary occlusion was 115.7 +/- 1.2 % of baseline in animals with VF and 111.4 +/- 0.9 % in those without (P = 0.007), and was the strongest predictor of this arrhythmia (P = 0.003) after adjusting for treatment and other possible confounding variables. Thus, the dilation of the ischemic region is closely and independently associated with VF following coronary occlusion. Although the interventions tested in the present study failed to protect against this arrhythmia, the results strongly suggest an influence of ischemic dilation on VF. |
2,896 | Public use of automated external defibrillators. | Automated external defibrillators save lives when they are used by designated personnel in certain public settings. We performed a two-year prospective study at three Chicago airports to assess whether random bystanders witnessing out-of-hospital cardiac arrests would retrieve and successfully use automated external defibrillators.</AbstractText>Defibrillators were installed a brisk 60-to-90-second walk apart throughout passenger terminals at O'Hare, Midway, and Meigs Field airports, which together serve more than 100 million passengers per year. The use of defibrillators was promoted by public-service videos in waiting areas, pamphlets, and reports in the media. We assessed the time from notification of the dispatchers to defibrillation, survival rate at 72 hours and at one year among persons with cardiac arrest, their neurologic status, and the characteristics of rescuers.</AbstractText>Over a two-year period, 21 persons had nontraumatic cardiac arrest, 18 of whom had ventricular fibrillation. With two exceptions, defibrillator operators were good Samaritans, acting voluntarily. In the case of four patients with ventricular fibrillation, defibrillators were neither nearby nor used within five minutes, and none of these patients survived. Three others remained in fibrillation and eventually died, despite the rapid use of a defibrillator (within five minutes). Eleven patients with ventricular fibrillation were successfully resuscitated, including eight who regained consciousness before hospital admission. No shock was delivered in four cases of suspected cardiac arrest, and the device correctly indicated that the problem was not due to ventricular fibrillation. The rescuers of 6 of the 11 successfully resuscitated patients had no training or experience in the use of automated defibrillators, although 3 had medical degrees. Ten of the 18 patients with ventricular fibrillation were alive and neurologically intact at one year.</AbstractText>Automated external defibrillators deployed in readily accessible, well-marked public areas in Chicago airports were used effectively to assist patients with cardiac arrest. In the cases of survivors, most of the users had no duty to act and no prior training in the use of these devices.</AbstractText>Copyright 2002 Massachusetts Medical Society</CopyrightInformation> |
2,897 | The end-of-study patient survey: methods influencing response rate in the AVID Trial. | Patient surveys are commonly distributed at the end of a multicenter clinical trial. This Antiarrhythmics Versus Implantable Defibrillators (AVID) substudy prospectively explored the relationship between methods used in distributing a survey and the quantity of responses received. AVID was a multicenter, randomized trial comparing survival in arrhythmia patients treated with antiarrhythmic drugs versus implantable defibrillators. At study termination, a patient satisfaction survey was mailed to the 664 surviving participants. Questions included reasons for study participation, study benefits and problems and quality of care. Survey mailings were stratified by four factors in a 2x2x2x2 factorial design: delivery mode (overnight vs. regular mail), certificate of appreciation, timing of administration ("early" vs. "late") and cover letter signed by a physician versus coordinator. Patients were randomly assigned to received one of 16 combinations of these four factors. Clinical characteristics and response rates were evaluated. Patients were more likely to return surveys delivered by overnight mail (75% vs. 68%, p=0.04), with no certificate of appreciation enclosed (75% vs. 68%, p=0.05) and administered close to the time of study closeout (79% vs. 72%, p=0.085). Compared to the 184 nonrespondents, the 456 (71%) respondents were older, Caucasian, lived with others, were high school graduates and less likely to have Medicare/Medicaid or HMO insurance (p<0.03). Physician recommendation was the most common reason cited for trial participation. Main benefits included increased knowledge of their medical condition and improved health. Reported problems included parking, transportation and excess clinic wait time. This randomized study demonstrated that methods of patient survey distribution affect the survey return rate. Additional studies should explore mechanisms for maximizing return rates. |
2,898 | Determinants and prognostic value of left atrial volume in patients with dilated cardiomyopathy. | We aimed to investigate the determinants of left atrial (LA) volume and its prognostic value in patients with dilated cardiomyopathy (DCM).</AbstractText>Enlargement of the LA is a marker of mortality in the general population. Patients with DCM are characterized by a wide range of LA sizes, but the clinical role of this observation has been played down.</AbstractText>A complete echocardiographic Doppler examination was performed in 337 patients (age 60 +/- 13 years; 84% male) with the diagnosis of DCM. Left atrial maximal volume (LA(max)) was measured at left ventricular (LV) end systole (four-chamber view; area-length method). Left ventricular end-diastolic and end-systolic volumes (LVEDV and LVESV) and ejection fraction (EF) were also measured. Mitral regurgitation (MR) was graded using a 5-point scale. Mitral E-wave (E) and A-wave (A) velocities, as well as their ratio (E/A), were measured off-line.</AbstractText>Determinants of LA(max) were: atrial fibrillation (r = 0.34, p < 0.0001), LVEDV (r = 0.46, p < 0.0001), EF (r = 0.40, p < 0.0001), MR (r = 0.39, p < 0.0001), and E/A ratio (r = 0.36, p < 0.0001). During follow-up (41 +/- 29 months), 77 patients died and 12 underwent heart transplantation. Univariate Cox analysis showed that LA(max) (hazard ratio [HR] 1.01, 95% confidence interval [CI] 1.007-1.013, p < 0.0001), LVESV (HR 1.003, CI 1.001-1.005, p = 0.0003), E/A ratio (HR 1.6, CI 1.3-2.005, p < 0.0001), and MR (HR 1.21, CI 1.03-1.44, p = 0.02) were related to the outcome. On bivariate Cox analysis, LA(max) predicted the prognosis independently of each determinant. Patients with a larger LA volume (LA(max)/m(2) >68.5 ml/m(2)) had a risk ratio of 3.8 compared with those with a smaller LA volume.</AbstractText>In patients with DCM, LA volume is associated with LV remodeling, diastolic dysfunction, and the degree of MR. The maximal volume of the LA has an independent and incremental prognostic value, compared with all its determinants.</AbstractText> |
2,899 | Ibutilide in rapid conversion of atrial flutter in octogenarians. | Atrial flutter is a common sustained atrial tachyarrhythmia for which frequency increases with age. Ibutilide is a novel class III antiarrhythmic agent used for the rapid cardioversion of atrial fibrillation or atrial flutter.</AbstractText>The aim of our study was to assess the use of ibutilide in a selected population of very elderly patients (octogenarians) with recent-onset atrial flutter.</AbstractText>Twenty-nine consecutive elderly patients (11 male, 18 female; mean age 83 +/- 3 years; interquartile range of 10) with recent-onset atrial flutter were included in the study; none of them had signs or symptoms of severe heart failure, angina or impaired renal or hepatic function. All patients underwent a 10-minute intravenous infusion of ibutilide (0.87 mg in 10 ml).</AbstractText>The rate of successful arrhythmia termination was 75.9% within a mean time of 31 +/- 20 minutes. No clinical variables were shown to be associated with successful cardioversion, although there was a tendency towards higher efficacy in patients with a shorter duration of arrhythmia. Two female patients (6.9%) developed torsade de pointes, requiring direct current cardioversion under general anaesthesia. Episodes of nonsustained ventricular tachycardia occurred in two other patients.</AbstractText>Ibutilide appears to be an effective and well tolerated drug for rapid conversion of recent-onset atrial flutter in octogenarian patients, and may represent a valid approach in the acute management of atrial flutter in this particular set of patients.</AbstractText> |
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