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2,700 | [Tachycardia-induced cardiomyopathy, unusual and reversible cause of left ventricular dysfunction: report of 9 cases]. | In this study, 9 cases of tachycardia-induced cardiomyopathy have been reported, with a 7-year follow-up period. The patient population consisted of 5 males and 4 females with a mean age of 41 +/- 18 years (range: 10-70 years). It was difficult to determine the onset of the arrhythmia, due to its frequently asymptomatic course until such time as cardiac insufficiency became apparent (this was the case in 7 patients, while 2 subjects had palpitations). Four cases of AV intranodal reentry tachycardia (3 with an accessory pathway), 2 cases of atrial fibrillation, 1 case of auricular flutter, 1 case of atrial tachycardia and 1 case of ventricular tachycardia were observed. Disappearance of the symptomatology following restoration of sinus rhythm was accompanied by echocardiographically-determined normalization of systolic function on average 5 +/- 4 months post-arrhythmia (range: 1-12 months). Left-ventricular end-diastolic volumes decreased from 60 +/- 5 mm to 51 +/- 4 mm (P < 0.01), and end-systolic volumes from 50 +/- 7 mm to 35 +/- 4 mm (P < 0.001), while the left ventricular shortening fraction increased from 17 +/- 5% to 33 +/- 4% (P < 0.0001). In the differential diagnosis for primary dilated cardiomyopathy, tachycardia-induced cardiomyopathy appears very similar to the former, and only an adequate period of follow-up after the restoration of sinus rhythm can confirm the diagnosis. |
2,701 | [Endocavitary implantation of a permanent pacemaker in the contralateral side of right pneumonectomy: a case report]. | The definitive endocardial stimulation is easy to install, allows a stable position of the leads, and a satisfactory stimulation thresholds for a long period. The epicardial approach is reserved for some rare indications including infectious contexts. The endocardial approach has been considered for a 67 years man with a complete AV block and an atrial fibrillation. This patient had undergone a right pneumonectomy 15 years before. A VVIR pacemaker has been implanted successfully by an internal jugular vein approach, and connected to a passively fixed unipolar lead. Because of the right ventricle deformation which made it unrecognizable, even by angiography means, we had to face major difficulties to position the lead. The epicardial approach should be considered even if a direct unique lung controlateral approach is easier than homolateral, because it allows us a quick ventricular access under the view control. |
2,702 | [Junctional tachycardia in adolescents: nodal reentry is the most frequent cause]. | Ventricular preexcitation syndromes are classically more common in the pediatric age group than in adults, and a latent Kent bundle may explain most cases of paroxysmal junctional tachycardia (PJT). These data stem from the results of intracardiac electrophysiologic testing, which is performed only in those patients at the most severe end of the symptom spectrum. The recent introduction of transesophageal testing has expanded the indications of electrophysiologic testing for PJT. This technique was used to determine the mechanism of PJT in 23 adolescents aged 11 to 9 years (mean age, 16 +/- 3 years) with paroxysmal palpitations, accompanied in seven cases with dizziness or syncope. Only four patients had documented PJT. The basal ECG was normal, and exercise testing showed no evidence of preexcitation. Pacing at increasing rates and programmed stimulation with one then two extra-stimuli was used and repeated, if needed, under infusion of 20 to 30 micrograms of isoproterenol.</AbstractText>PJT was induced in 21 patients (91%), under basal conditions in 13 and under isoproterenol in eight. Neither of the two patients with a negative test had documented tachycardia. Based on classic criteria (position of A relative to V1, effect of a bundle branch block, and shape of A in D1 and V1), the mechanism of the PJT was shown to be nodal reentry in 17 cases (81%) and reentry into a latent left-sided Kent's bundle in four cases. Atrial fibrillation was also induced in two of the patients with nodal reentry. In six of the patients with dizziness or syncope associated with palpitations, these symptoms were due to nodal reentry.</AbstractText>Nodal reentry is very common in adolescents and can explain symptoms ascribed to "spasmophilia", as well as some cases of malaise or syncope.</AbstractText> |
2,703 | Histochemical and ultrastructural characterisation of an arrhythmogenic substrate in ischemic pig heart. | The aim of the present study was to reveal by enzyme histochemistry and ultrastructural examination the possible anatomic substrate that may be the cause of high susceptibility of the pig heart to ischemia and/or reperfusion-induced severe arrhythmias. The heart of landrace pigs was subjected to 90 min of left coronary occlusion followed by 30 min reperfusion, whereby both conditions elicited arrhythmias and often even ventricular fibrillation. We found for the first time, besides common contractile cardiomyocytes, Purkinje fibers, and "transitional cells" in mid-myocardium. Transitional cells likely correspond to the recently described M cells. Importantly, these cells and Purkinje fibers exhibited reversible ischemia-related subcellular alterations, whereas the majority of contractile cardiomyocytes were irreversibly injured in the area of infarction. In correlation with these findings, glycogen-dependent phosphorylase activity was abolished, whereas it was still persistent in Purkinje fibers and small islands of contractile cardiomyocytes. Moreover, a distinct heterogeneity in the activity of all enzymes selected and subcellular alterations within a border zone were observed. These results suggest that particularly the preserved viability of specialized conducting cells spanning the ventricular wall may account for electrical disturbances that consequently contribute to increased susceptibility of the pig heart to ischemia- and reperfusion-induced severe arrhythmias. |
2,704 | Gap junction remodelling is involved in the susceptibility of diabetic rats to hypokalemia-induced ventricular fibrillation. | The objective of the present study was to examine the susceptibility of diabetic rats with cardiomyopathy to hypokalemia-induced ventricular fibrillation and to localize gap junction protein connexin-43 as well as subcellular changes that may be involved in the development of severe arrhythmia. Our results showed a significantly higher incidence of sustained ventricular fibrillation in diabetic hearts as compared with control hearts, 80% vs 20%, respectively. Diabetic cardiomyopathy itself was accompanied by a distinct decrease in connexin-43-immunopositive gap junctions. Moreover, interstitial fibrosis and subcellular alterations to various degrees were observed in diabetic hearts, and a further deterioration of the ultrastructure and impairment of intercellular junctions, and a stronger local decrease in connexin-43 levels due to hypokalemia were found. These changes were heterogeneously distributed throughout the myocardium and occurred earlier and were more pronounced in diabetic hearts than control hearts. In conclusion, our results indicate that diabetic cardiomyopathy is associated with down-regulation of gap junction proteins and may account for the higher vulnerability of diabetic rats to ventricular fibrillation in combination with impairment of intercellular communication due to hypokalemia. |
2,705 | [Normal conventional electrocardiogram with negative pharmacological stress test does not rule out Brugada syndrome]. | The diagnosis of Brugada syndrome, or right bundle-branch block with an elevated ST segment and negative T waves in V1-3, is obscured by the transitory normalization of the electrocardiogram, which can be unmasked by administering sodium-channel blockers. It has been recently reported that the condition can be underdiagnosed if only conventional precordial leads are used. We present the cases of two asymptomatic patients, a mother and son, with a family history of sudden cardiac death in first-degree relatives. Baseline ECGs obtained in conventional leads and one and two intercostal spaces above conventional electrode sites were similar, normal in the mother and saddle-like in the son. A flecainide stress test elicited the characteristic pattern of Brugada syndrome in both patients, but only in the high leads. Pharmacological stress testing with conventional precordial lead recordings does not rule out Brugada syndrome. We recommend that ECG recordings should include leads in the second and third intercostal spaces. |
2,706 | Fiberglass needle electrodes for transmural cardiac mapping. | We developed a new method for fabricating plunge needle electrodes for use in cardiac mapping. The needles have 12 electrodes with 1-mm spacing, are 0.5 mm in diameter, and are fabricated from fiberglass reinforced epoxy. They are stiff enough to be easily inserted into beating hearts and durable enough to be reused many times. We found that these new needles elicit smaller, more quickly resolving injury potentials, and when inserted in a row with 2-mm spacing, disrupt ventricular fibrillation activation patterns less than traditional steel needles. |
2,707 | Quantitative assessment of the total myocardial uptake ratio of 123I-BMIPP by using the Ishii-MacIntyre method is useful for predicting cardiac complications in patients with mitochondrial encephalomyopathy or myotonic dystrophy. | We evaluated the usefulness of the total myocardial uptake ratio (TMUR) of 15-(p-[123I]iodophenyl)-3(R,S)-methyl-pentadecanoic acid (123I-BMIPP) for predicting cardiac complications in patients with mitochondrial encephalomyopathy or myotonic dystrophy. Six patients with mitochondrial encephalomyopathy, four with myotonic dystrophy, and 10 control subjects were studied. Quantitative assessment of 123I-BMIPP dynamic myocardial imaging was performed, and the TMUR of 123I-BMIPP was calculated according to the Ishii-MacIntyre method. Then, the TMUR was compared in the 10 patients and 10 healthy controls, and all patients were followed for 56.1+/-22.1 months to evaluate cardiac complications. TMUR in patients (2.69+/-0.64) was significantly (P =0.01) lower than that in controls (3.28+/-0.25). Three patients in whom the TMUR value was above 3.00 had no cardiac complications. On the other hand, all patients in whom TMUR was below 3.00 had some kind of cardiac complication during the follow-up period. Two patients showed progressive conduction abnormality and underwent pacemaker implantation, one patient had sick sinus syndrome and underwent pacemaker implantation, another patient showed non-sustained ventricular tachycardia and paroxysmal atrial fibrillation, and four of seven patients, including one with a pacemaker, showed an increased cardiothoracic ratio value over 50%. In conclusion, measurement of the TMUR by the Ishii-MacIntyre method is useful for evaluating the development of cardiac complications in patients with mitochondrial encephalomyopathy or myotonic dystrophy. |
2,708 | Clusters of ventricular fibrillation in a patient with an implantable cardioverter difibrillator treated with amiodarone. | A 44 year-old man with severe left ventricular dysfunction resulting from an old myocardial infarction developed clusters of ventricular fibrillation (VF). Although coronary bypass surgery was performed and heart failure was well controlled, the VF recurred during amiodarone therapy. Despite multiple deliveries of shocks by an implantable cardioverter defibrillator, the electrical storm could not be terminated. Some substrate for rapid ventricular tachyarrhythmias, refractory to class III drugs, can lead to death from arrhythmia. |
2,709 | Role of kappa-opioid receptor activation in pharmacological preconditioning of swine. | Pharmacological preconditioning with kappa-opioid receptor agonists is proarrhythmic and exerts antipreconditioning effects in rats. In swine, it is unknown whether kappa-opioid receptor stimulation plays a role in pharmacological preconditioning. Swine were preconditioned with 1) saline (controls), 2) [d-Ala(2),d-Leu(5)]enkephalin (DADLE), 3) morphine, 4) pentazocine, 5) norbinaltorphimine (nor-BNI), 6) DADLE + nor-BNI, 7) morphine + nor-BNI, or 8) pentazocine + nor-BNI before occlusion (45 min) and reperfusion (180 min) of the left anterior descending coronary artery. Infarct size to area at risk (IS), regional (systolic shortening) and global (pressures and flows) myocardial function, and arrhythmia occurrence were assessed. Only DADLE + nor-BNI preconditioning significantly decreased infarct size compared with controls (47 +/- 13 vs. 65 +/- 5%, P < 0.05); morphine preconditioning was not cardioprotective with or without kappa-opioid receptor blockade (nor-BNI). DADLE preconditioning significantly increased ischemia-induced arrhythmias relative to controls, whereas pentazocine-preconditioned animals (n = 2) experienced intractable ventricular fibrillation during ischemia. kappa-Opioid receptor blockade with DADLE or pentazocine preconditioning alleviated proarrhythmic effects. These results suggest that kappa-opioid receptor activation during pharmacological preconditioning is proarrhythmic in swine. |
2,710 | Off-pump coronary surgery: surgical strategy for the high-risk patient. | In a retrospective study, we compared two groups of consecutive patients operated by the same team during the year 2000 for coronary artery disease with the use of extracorporeal circulation (group 1, n=230) or on the beating heart using the Octopus II plus stabiliser (group 2, n=228). High-risk patients were identified by a EuroSCORE plus 6. EuroSCORE definitions and predicted risk models were utilized to compare the variables of the groups.</AbstractText>There were no significant differences between the preoperative variables of the groups in age, gender, left ventricular function, diabetes and peripheral vascular and renal disease as is indicated by the Euroscore (resp. 4.7/5.1 p=0.107). Calcification of the ascending aorta and chronic obstructive lung disease were statistically significant more prevalent in the beating heart group. No differences in preoperative variables in the high-risk patients group (Euroscore 8.5/8.1 p=0.356) except for calcification of the ascending aorta.</AbstractText>All patients underwent a full revascularisation through a midline sternotomy. Significant more distal anastomoses were performed in group 1 (3.7 per patient (1-6)) with regard to group 2 (2.9 per patient (1-6)). Anesthesia, postoperative treatment and follow up were equal for both groups. A significant lower incidence of atrial fibrillation (p=0.010), shorter ICU stay (p=0.031) and renal insufficiency (p=0.033) was reported in group 2. In the low risk group, we could not diagnose any difference between the two groups, except for atrial fibrillation. The benefits of the beating heart surgery however were more pronounced in the high-risk patient as is indicated by a significant reduction of the ICU stay by 1 day (3.5d/2.5d (p=0.028)), better preservation of the renal function (p=0.017) and a significant reduction of the length of hospital stay by more than two days (p=0.040). A lower incidence of atrial fibrillation, however not significant.</AbstractText>In our experience, beating heart surgery is a safe alternative for conventional coronary heart surgery. High-risk patients do benefit most from this technique. It became our first choice in the elderly patient and patients presenting with higher co-morbidities.</AbstractText> |
2,711 | The effect of the isomers of cyclo(Trp-Pro) on heart and ion-channel activity. | Cyclo(L-Trp-L-Pro) has shown potential for use in the treatment of cardiovascular dysfunction. The aim of the study was to determine the effects of the isomers of cyclo(Trp-Pro) - cyclo(L-Trp-L-Pro), cyclo(L-Trp-D-Pro), cyclo(D-Trp-L-Pro) and cyclo(D-Trp-D-Pro) - on heart and ion-channel activity. The effects on L-type Ca(2+)-channel, Na(+)-channel and inward rectifier K(+)-channel activity were determined by using the whole-cell patch-clamp technique on myocytes of guinea-pig origin. Dependence on the membrane potential in terms of Ca(2+)-channel activity was also investigated. A modified Langendorff method was used to determine the effects of the isomers on heart rate, coronary flow, duration of ventricular tachycardia and arrhythmia, time to sinus rhythm and QRS interval on the rat isolated heart. Cyclo(L-Trp-L-Pro), cyclo(L-Trp-D-Pro) and cyclo(D-Trp-D-Pro), 100 microM, showed agonism towards Ca(2+)-channel activity, while cyclo(D-Trp-L-Pro) caused a blockage of the current. The action of cyclo(D-Trp-L-Pro) was shown to be independent of membrane potential. No significant effect (P > 0.05) on the inward rectifier K(+) current was observed in the presence of cyclo(L-Trp-D-Pro) and cyclo(D-Trp-D-Pro), while antagonism was noted in the presence of cyclo(L-Trp-L-Pro) and cyclo(D-Trp-L-Pro). All isomers showed antagonist effects on the Na(+) channel. No adverse effects were noted on chronotropic effects in the presence of 200 microM cyclo(L-Trp-L-Pro) and cyclo(D-Trp-D-Pro) (P > 0.05), while cyclo(L-Trp-D-Pro) significantly increased the heart rate. Cyclo(D-Trp-L-Pro) significantly reduced the heart rate (P < 0.05). In addition, no significant effects were observed on the coronary flow rate in the presence of the isomers. All isomers significantly reduced the duration of ventricular tachycardia and arrhythmia, as well as the time to sinus rhythm. Furthermore, no change in the QRS intervals was noted in the presence of the isomers in comparison with the control, with a significant increase being noted for cyclo(D-Trp-D-Pro) (P < 0.05) in reference to the other isomers. The isomers thus show antiarrhythmic potential and may manifest as novel agents in the treatment of cardiovascular dysfunction, since a decrease in ventricular fibrillation may reduce the mortality rates in acute myocardial infarction. |
2,712 | Current issues in cardiopulmonary resuscitation. | Current Advanced Cardiac Life Support (ACLS) guidelines and emergency medical services (EMS) clinical protocols usually recommend immediate defibrillation for victims of out-of-hospital cardiac arrest who have ventricular fibrillation (VF). However, animal studies and results from a small number of clinical investigations now suggest that a short period of chest compressions or ACLS procedures delivered before defibrillation may improve the outcome of patients with prolonged VF. Although the basic science and clinical data supporting a chest-compression-first procedure are compelling, large, multicenter randomized trials are still necessary to determine whether such protocols do indeed improve outcome. In current EMS dispatch practice, traditional cardiopulmonary resuscitation (CPR) instructions are given when needed to bystanders who report a possible cardiac arrest. Recent literature has shown that in certain circumstances, CPR instructions involving chest compressions alone may be given more quickly and can yield an equivalent, if not better, chance of survival. Although this practice is controversial, the general consensus is that any CPR is better than none at all. Therefore, telephone CPR protocols that recommend the immediate initiation of chest compressions may be preferred, particularly for callers who have no previous training in CPR. |
2,713 | Prehospital management of acute tachyarrhythmias. | Arrhythmias are commonly encountered by emergency medical services (EMS) personnel. The potential seriousness of acute symptomatic arrhythmias necessitates thorough up-to-date training of EMS personnel. The three most common acute tachyarrhythmias, not linked to cardiac arrest, that are observed outside the hospital are paroxysmal supraventricular tachycardia (PSVT), atrial fibrillation with rapid ventricular response (RAF), and perfusing ventricular tachycardia (VT). Ideally, these tachyarrhythmias should be operationally defined in a manner that simplifies, particularly for EMS providers, their diagnosis and treatment. The authors recommend referring to these rhythms as regular narrow-complex tachycardia (presumed PSVT), irregularly irregular narrow-complex tachycardia (presumed RAF), or regular wide-complex tachycardia (presumed VT or aberrantly conducted PSVT). Although the value of treatments such as cardioversion is widely understood, the benefit from others, such as lidocaine, is unclear. Current preferences, recommendations, and concerns regarding the treatment of most arrhythmias outside the hospital reflect the dichotomy that sometimes exists between available evidence and actual practice. |
2,714 | Effect of adrenergic stimulation on action potential duration restitution in humans. | Enhanced sympathetic activity facilitates complex ventricular arrhythmias and fibrillation. The restitution properties of action potential duration (APD) are important determinants of electrical stability in the myocardium. Steepening of the slope of APD restitution has been shown to promote wave break and ventricular fibrillation. The effect of adrenergic stimulation on APD restitution in humans is unknown.</AbstractText>Monophasic action potentials were recorded from the right ventricular septum in 18 patients. Standard APD restitution curves were constructed at 3 basic drive cycle lengths (CLs) of 600, 500, and 400 ms under resting conditions and during infusion of isoprenaline (15 patients) or adrenaline (3 patients). The maximum slope of the restitution curves was measured by piecewise linear regression segments of sequential 40-ms ranges of diastolic intervals in steps of 10 ms. Under control conditions, the maximum slope was steeper at longer basic CLs; eg, mean values for the maximum slope were 1.053+/-0.092 at CL 600 ms and 0.711+/-0.049 at CL 400 ms (+/-SEM). Isoprenaline increased the steepness of the maximum slope of APD restitution, eg, from a maximum slope of 0.923+/-0.058 to a maximum slope of 1.202+/-0.121 at CL 500 ms. The effect of isoprenaline was greater at the shorter basic CLs. A similar overall effect was observed with adrenaline.</AbstractText>The adrenergic agonists isoprenaline and adrenaline increased the steepness of the slope of the APD restitution curve in humans over a wide range of diastolic intervals. These results may relate to the known effects of adrenergic stimulation in facilitating ventricular fibrillation.</AbstractText> |
2,715 | Near-infrared fluorescence coronary angiography: a new noninvasive technology for intraoperative graft patency control. | Intraoperative graft patency verification is of major clinical importance for quality control after coronary artery bypass grafting (CABG), especially if surgery is performed on the beating heart. This is one of the first reports of fluorescence coronary angiography (FCA) using the dye indocyanine green (ICG), a noninvasive technology for direct visualization of coronary arteries, bypass grafts, and myocardial perfusion.</AbstractText>Twenty-three domestic pigs (weight, 45-72 kg) underwent FCA of the left anterior descending coronary artery (LAD). In the first group (n = 6 pigs), FCA was used to visualize the native coronary vessels and myocardial perfusion. In the second group (n = 8 pigs), 14 stenoses of various degrees and 4 total vessel occlusions were created by snares on different segments of the LAD, and FCA was used to visualize the effects of these obstructions. In the third group (n = 9 pigs), a coronary bypass procedure on the beating heart was performed by a left internal mammary artery or a human saphenous vein graft to the LAD, and FCA was used to visualize graft patency. Three pigs were removed from the study because of ventricular fibrillation. ICG was intravenously applied, and the heart was illuminated with near-infrared light emitted by laser diodes. The fluorescence emission was detected by an adapted charge-coupled device camera system. The images were displayed in real time on a high-resolution monitor. Subsequently, images obtained with FCA were compared to those obtained with coronary angiography (n = 10 pigs).</AbstractText>In all cases, high-quality FCA images of coronary arteries and myocardial perfusion were obtained. All stenoses resulted in an impairment of the myocardial perfusion visualized by FCA. Occlusion of the LAD or the diagonal branch resulted in a total perfusion defect of the corresponding anterior myocardial wall with immediate reperfusion after releasing the snare. In 5 cases a patent bypass graft with an apparent homogenous perfusion of the corresponding myocardium was detectable. In one procedure, FCA images indicated total occlusion of the bypass graft and a total perfusion deficit in the distal LAD region. Correlation between FCA and coronary angiography in detection of stenoses and graft patency was excellent.</AbstractText>With the fluorescence technique using ICG, visualization of blood flow in coronary vessels and bypass grafts, as well as of myocardial perfusion, is feasible. FCA is a highly sensitive and reproducible method and an excellent technique for intraoperative quality control in CABG.</AbstractText> |
2,716 | On-pump coronary artery surgery versus off-pump exclusive arterial coronary grafting: a matched cohort comparison. | It is unknown whether coronary artery bypass grafting without cardiopulmonary bypass and with exclusive use of arterial grafts (arterial off-pump CABG) offers any significant short-term advantages over standard CABG with cardiopulmonary bypass. Accordingly, we performed a comparison of the short-term outcomes of arterial off-pump and standard CABG patients matched for preoperative risk and number of grafts.</AbstractText>We studied 90 consecutive arterial off-pump CABG patients during a 2-year period, obtained demographic and clinical features and surgical characteristics, and calculated their predicted surgical risk (EuroSCORE). Using a database of 750 contemporaneous patients treated with standard CABG, we created a matched cohort of 90 patients using an iterative process prioritizing number of grafts, target vessels, EuroSCORE, age, and sex. We compared the two groups for baseline features and short-term clinical outcomes.</AbstractText>There were no differences in age (65.9 versus 64.7 years), sex, EuroSCORE (3.3 versus 3. 6), number of grafts (2.1 versus 2.1), and preoperative left ventricular function. Arterial off-pump CABG, however, was associated with decreased duration of operation (213 versus 252 minutes; p < 0.0013), decreased peak postoperative troponin I levels (mean, 10.8 versus 29.1 ng/mL; p < 0.0001), decreased peak norepinephrine dose (2.3 versus 4.1 microg/ min; p < 0.0082), and decreased likelihood of receiving red blood cell transfusion (17.8% versus 40%; p = 0.0016). There were no differences in duration of intensive care unit or hospital stay, incidence of atrial fibrillation, or other clinical complications. There was one death in each group.</AbstractText>After matching for number of grafts and other important preoperative risk markers, arterial off-pump CABG still decreases the need for red blood cell transfusion and offers other moderate clinical advantages compared with standard on-pump CABG.</AbstractText> |
2,717 | Does Cl-/HCO3- exchange play an important role in reperfusion arrhythmias in rats? | The protective effects of Cl(-)/HCO(3)(-) exchange inhibitors, 4,4'-diisothiocyano-stilbene-2,2'-disulfonic acid (DIDS) and 4-acetamido-4'isothiocyanato-stilbene-2,2'-disulfonic acid (SITS), against reperfusion-induced arrhythmias were investigated in anesthetized rats. Rats were subjected to 5-min occlusion of the left coronary artery followed by 10-min reperfusion. All drugs were intravenously administered 5 min before the onset of occlusion. DIDS (75 mg/kg) reduced the incidence of ventricular fibrillation and mortality to 0%, whereas SITS (75 mg/kg) only decreased these parameters to 60%. DIDS simultaneously decreased the mean blood pressure and heart rate, and prolonged PQ and QRS intervals, whereas SITS produced a weaker effect on these parameters and no change in QRS interval. Mexiletine (5 mg/kg), which had been demonstrated to suppress the arrhythmias and reduce the heart rate and mean blood pressure in this model, was shown to prolong PQ and QRS intervals. Verapamil (0.5 mg/kg) or diltiazem (0.4 mg/kg) suppressed the arrhythmias, simultaneously decreasing the heart rate and mean blood pressure and prolonging PQ interval. The results indicate that the protective effect of DIDS on reperfusion arrhythmias in the anesthetized rats is unlikely to be attributed to the inhibitory action on Cl(-)/HCO(3)(-) exchange, but possibly mediated by its blocking effects on cardiac ion channels, such as Na(+) or Ca(2+) channels. |
2,718 | Maximum left ventricular thickness and risk of sudden death in patients with hypertrophic cardiomyopathy. | We sought to assess the relationship between maximum left ventricular (LV) wall thickness and outcome in patients with hypertrophic cardiomyopathy (HCM).</AbstractText>An association between maximum LV wall thickness and risk of sudden death was suggested in HCM. This finding requires further investigation, given the important implications for risk stratification and treatment.</AbstractText>We analyzed the mortality and risk profile of 237 patients (age 41 +/- 17 years; 63% male) classified into five groups based on echocardiographic maximum LV thickness.</AbstractText>During follow-up (12 +/- 7 years), 36 patients died of cardiovascular causes, including 16 sudden deaths. Maximum LV thickness was not associated with a risk of sudden death (p = 0.37) nor with overall cardiovascular mortality (p = 0.7). With the exception of the small subset with thickness values < or =15 mm, with a consistently benign clinical course, the distribution of sudden death and overall cardiovascular mortality was not significantly different among the other four classes, ranging from 16 to 19 mm to > or =30 mm. Among 30 patients with extreme LV thickness (> or =30 mm), only one sudden event occurred among six patients diagnosed at <18 years of age (17%) and none among 24 diagnosed at > or =18 years of age. The prevalence of nonsustained ventricular tachycardia, syncope, an abnormal blood pressure response to exercise, and atrial fibrillation was similar among the five thickness classes.</AbstractText>During 12-year follow-up, we observed no association between maximum LV thickness and cardiovascular mortality in a community-based population with HCM. The degree of maximum LV wall thickness should be considered in the context of a multifactorial approach to risk stratification, rather than as an isolated risk factor. Only in those patients diagnosed at a very young age might the presence of extreme LV wall thickness represent, per se, a potential marker of risk of sudden death.</AbstractText> |
2,719 | Amiodarone and the risk of bradyarrhythmia requiring permanent pacemaker in elderly patients with atrial fibrillation and prior myocardial infarction. | The aim of this study was to determine whether the use of amiodarone in patients with atrial fibrillation (AF) increases the risk of bradyarrhythmia requiring a permanent pacemaker.</AbstractText>Reports of severe bradyarrhythmia during amiodarone therapy are infrequent and limited to studies assessing the therapy's use in the management of patients with ventricular arrhythmias.</AbstractText>A study cohort of 8,770 patients age > or =65 years with a new diagnosis of AF was identified from a provincewide database of Quebec residents with a myocardial infarction (MI) between 1991 and 1999. Using a nested case-control design, 477 cases of bradyarrhythmia requiring a permanent pacemaker were matched (1:4) to 1,908 controls. Multivariable logistic regression was used to estimate the odds ratio (OR) of pacemaker insertion associated with amiodarone use, controlling for baseline risk factors and exposure to sotalol, Class I antiarrhythmic agents, beta-blockers, calcium channel blockers, and digoxin.</AbstractText>amiodarone use was associated with an increased risk of pacemaker insertion (OR: 2.14, 95% confidence interval [CI]: 1.30 to 3.54). This effect was modified by gender, with a greater risk in women versus men (OR: 3.86, 95% CI: 1.70 to 8.75 vs. OR: 1.52, 95% CI: 0.80 to 2.89). Digoxin was the only other medication associated with an increased risk of pacemaker insertion (OR: 1.78, 95% CI: 1.37 to 2.31).</AbstractText>This study suggests that the use of amiodarone in elderly patients with AF and a previous MI increases the risk of bradyarrhythmia requiring a permanent pacemaker. The finding of an augmented risk of pacemaker insertion in elderly women receiving amiodarone requires further investigation.</AbstractText> |
2,720 | Gender, age, and heart failure with preserved left ventricular systolic function. | This study was designed to determine if women are more likely than men to have heart failure (HF) with preserved systolic function after adjustment for potential confounders, including age.</AbstractText>Although prior evidence suggests an independent association between female gender and preserved left ventricular systolic function (LVSF) in patients with HF, existing studies are limited by referral biases, small sample sizes, or the inability to adjust for a wide range of potential confounding variables.</AbstractText>This is a cross-sectional study using data from retrospective medical chart abstraction of a national sample of Medicare beneficiaries hospitalized with the principal discharge diagnosis of HF in acute-care nongovernmental hospitals in the U.S. between April 1998 and March 1999. Patients were eligible for this analysis if they were age 65 years or older, had documentation of LVSF, and corroboration of the diagnosis of HF. We used multivariable logistic regression to identify the correlates of preserved LVSF, which was defined as qualitatively normal function or quantitatively reported ejection fraction > or =0.50. Stratified regressions by gender were performed to identify significant interactions.</AbstractText>Of the 19,710 patients in the analysis, preserved LVSF was present in 6,700 (35%), 79% of whom were women. In contrast, among the 12,956 patients with impaired LVSF, only 49% were women. Patients with preserved LVSF were 1.5 years older than those with impaired LVSF. After adjustment for age and other patient factors, female gender remained strongly associated with preserved LVSF (calculated risk ratio = 1.71; 95% confidence interval 1.63 to 1.78). The association was consistent in all age groups, and was similar in patients with or without coronary artery disease, hypertension, pulmonary disease, renal insufficiency, or atrial fibrillation.</AbstractText>In elderly patients hospitalized with HF, preserved systolic function is primarily a condition of women, independent of important demographic and clinical characteristics.</AbstractText> |
2,721 | American College of Cardiology/American Heart Association Chronic Heart Failure Evaluation and Management guidelines: relevance to the geriatric practice. | Heart failure (HF) is the only cardiovascular disease with increasing incidence and prevalence. Most HF patients are older adults. With the aging of the population and effective treatment of hypertension and coronary artery disease, the two major underlying causes of HF, the number of older Americans with HF is expected to rise significantly in the coming decades. HF is the number one hospital discharge diagnosis for older adults. It is one of the causes of frequent hospital readmissions, reflecting acute decompensation and compromised quality of life for patients and increased cost and resource use for the healthcare system. It is also associated with approximately 300,000 deaths annually, most in older adults. Advances in the management of HF in the past several decades have significantly decreased the mortality and morbidity associated with this condition. Randomized controlled trials have demonstrated the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, beta-blockers, and spironolactone on survival and quality of life of HF patients, but there is evidence of underuse of evidence-based care for HF. Several national guidelines have been published since 1994 that recommended evidence-based evaluation and management of HF. In 1995, the American College of Cardiologists (ACC) and the American Heart Association (AHA) published their first HF guidelines that recommended left ventricular (LV) function evaluation for all patients presenting with HF and use of ACE inhibitors for all patients with LV systolic dysfunction (LVSD) unless contraindicated. The guidelines recommended the use of hydralazine and isosorbide dinitrate in patients who could not use ACE inhibitors. In addition, digoxin was recommended in patients with HF due to LVSD but not adequately responsive to ACE inhibitors and diuretics and in those with atrial fibrillation and rapid ventricular rates. Diuretic use was recommended for symptomatic patients with evidence of fluid overload. Use of anticoagulation was restricted to patients with atrial fibrillation or to those with a history of systemic or pulmonary embolism. Beta-blockers were reserved for HF patients after acute myocardial infarctions. Recent advances in the management of HF called for a revision of the guidelines.</AbstractText>The purpose of revising the 1995 ACC/AHA guidelines was to incorporate recent advances in pharmacological and nonpharmacological approaches to HF treatment and to assist physicians in clinical decision-making in the management of HF.</AbstractText>The ACC/AHA invited representatives from the American College of Chest Physicians, the Heart Failure Society of America, the International Society for Heart and Lung Transplantation, the American Academy of Family Physicians, and the American College of Physicians-American Society of Internal Medicine to participate in the preparation of the guidelines. The writing committee searched pertinent medical literature in English using computerized databases such as MEDLINE and EMBASE and manually searching the bibliographies of the selected articles. The writing committee classified HF into four stages, including patients who are at high risk for developing HF. According to this new classification, Stage A and B represent asymptomatic patients, the former at high risk for developing HF but no structural disorder, the latter with structural disorders of the heart. Stage C encompasses patients with underlying structural heart disorders who are symptomatic, either currently or in the past. Stage D includes end-stage HF patients. This new classification is intended to complement the New York Heart Association (NYHA) functional classification of HF into Class I (asymptomatic), Class II (symptomatic on less than ordinary exertion), Class III (symptomatic on ordinary exertion), and Class IV (symptomatic at rest).</AbstractText>The recommendations are categorized into those for evaluation and management.</AbstractText> |
2,722 | Amiodarone: an emergency medicine perspective. | Amiodarone is a highly efficacious antiarrhythmic agent for many cardiac arrhythmias, ranging from atrial fibrillation to malignant ventricular rhythm disturbances. Significant interest has developed in recent years with the publication of randomized controlled trials supporting the efficacy of amiodarone over placebo and lignocaine for improving survival to hospital in patients with shock-resistant ventricular fibrillation. Amiodarone has complex pharmacological and pharmacokinetic properties. It has significant long-term adverse effects, but short-term administration of intravenous amiodarone is generally well tolerated. This article will explore issues related to the clinical use of amiodarone from an emergency medicine perspective. |
2,723 | [Hepatic toxicity of propafenone: a case description]. | A case of acute liver injury associated with the use of the antiarrhythmic drug propafenone in a 62-year-old woman undergoing clinical observation for recurrent atrial fibrillation is reported. Propafenone hydrochloride, a class 1C antiarrhythmic drug widely used in the clinical practice for the treatment of supraventricular and ventricular arrhythmias, rarely (0.1-0.2% of incidence) causes liver injury characterized by a rise in hepatic cell enzymes or cholestatic enzymes or both. Within 2 months of the discontinuation of therapy the liver function tests return to normal, therefore there are no known fatalities secondary to propafenone liver injury including fulminant hepatitis and death. The close temporal relationship between the administration of the drug and the acute onset of signs of liver injury, the marked rise in liver function tests following the increase of the drug dosage and their gradual normalization after its withdrawal strongly suggest that propafenone is involved in the pathogenesis of this syndrome. Although rare, hepatotoxicity due to this widely used antiarrhythmic drug should be borne in mind in the differential diagnosis of sudden hepatocellular or cholestatic syndrome of obscure origin. It seems prudent to obtain baseline liver function before starting therapy with propafenone and then follow up laboratory tests some months later at least in patients with known liver disease. |
2,724 | Predictors of stroke mortality in elderly people from the general population. The CArdiovascular STudy in the ELderly. | Stroke occurs particularly frequently in elderly people and, being more often disabling than fatal, entails a high social burden. The predictors of stroke mortality have been identified in 3282 subjects aged > or = 65 years, taking part in the CArdiovascular STudy in the ELderly (CASTEL), a population-based study performed in Northeast Italy. Historical and clinical data, blood tests and 14-year fatal events were recorded. Continuous items were divided into quintiles and, for each quintile, adjusted relative risk (RR) with 95% confidence intervals [CI] was derived from multivariate Cox analysis. Age, historical stroke (RR: 5.2; 95% CI: 3.18-8.6) and coronary artery disease (RR: 1.38; CI: 1.18-2.1), atrial fibrillation (RR: 2.40; CI: 1.42-4.0), arterial hypertension (RR: 1.33; CI: 1.15-1.76), systolic blood pressure > or = 163 mmHg (RR: 1.84; CI: 1.20-2.59), pulse pressure > or = 74 mmHg (RR: 1.50; CI: 1.13-2.40), cigarette smoking (RR: 1.60; CI: 1.03-2.47), electrocardiographic left ventricular hypertrophy (RR: 1.72; CI: 1.10-2.61), impaired glucose tolerance (IGT, RR: 1.83; CI: 1.10-3.0), uric acid (UA) > 0.38 mmol/l (RR: 1.61; CI: 1.14-2.10), serum potassium > or = 5 mEq/l (RR: 1.70; CI: 1.24-2.50) and serum sodium < or = 139 mEql/l (RR: 1.34; 1.10-2.10) increased the risk of stroke. In the CASTEL, stroke was the first cardiovascular cause of death. Some independent predictors usually unrelated to stroke mortality (namely pulse pressure, pre-diabetic IGT, UA and blood electrolytes disorders) have been identified. |
2,725 | QT dispersion in infants with apparent life-threatening events syndrome. | Apparent life-threatening event (ALTE) is a term used to define an event of unknown cause after an infant is found limp, cyanotic, bradycardic, and/or requires resuscitation. Eight to 15% of children with ALTE die of sudden infant death syndrome. Obstructive sleep apnea, bradycardia, gastroesophageal reflux, and laryngotracheal abnormalities are frequently associated with ALTE. Wide QT dispersion is associated with sudden death in heart failure and increased risk of ventricular fibrillation in acute myocardial infarction. Here, we assess QT dispersion in infants with ALTE and its correlation to clinical and electrocardiographic indices. The study included eighty nine infants (age 2.14 +/- 1.8 months, 46 males and 43 females) referred with ALTE to the pediatric emergency room and 18 controls (age 2.77 +/- 2.2 months) who underwent electrocardiogram assessment of QTmin, QTmax, QT dispersion (QT-D), and as well as QTmin, QTmax, and QT-D corrected for heart rate (QTcmin, QTcmax, QTC-D, respectively). All infants were referred at the usual diagnostic tests-the gastroesophageal reflux test, apnea monitoring, Holter ECG monitoring, electroencephalogram, and Doppler echocardiography. QT-D, QTc-D, and QTc-min were significantly greater in the ALTE group (p < 0.01). Greater QTc-D was found in males compared to females (p < 0.001). QT-D and QTc-D showed little or no correlation with age of infant or positivity of diagnostic tests. QTc has been found by multiple regression analysis to be the independent variable with the greatest impact on QTc-D (beta = -0.68, p < 0.001). |
2,726 | The incidence of arrhythmias in a pediatric cardiac intensive care unit. | A pediatric cardiac intensive care unit (CICU) manages critically ill children and adults with congenital or acquired heart disease. These patients are at increased risk for arrhythmias. The purpose of this study was to prospectively evaluate the incidence of arrhythmias in a pediatric CICU patient population. All patients admitted to the CICU at the Cardiac Center at The Children's Hospital of Philadelphia between December 1, 1997, and November 30, 1998, were evaluated prospectively from CICU admission to hospital discharge via full disclosure telemetry reviewed every 24 hours. Arrhythmias reviewed included nonsustained and sustained ventricular tachycardia (VT), nonsustained and sustained supraventricular tachycardia (SVT), atrial flutter and fibrillation, junctional ectopic tachycardia, and complete heart block. We reviewed 789 admissions consisting of 629 patients (age range, 1 day-45.5 years; median, 8.1 months). Hospital stay ranged from 1 to 155 days (total of 8116 patient days). Surgical interventions (n = 602) included 482 utilizing cardiopulmonary bypass. During the study period, there were 44 deaths [44/629 patients (7.0%)], none of which were directly attributable to a primary arrhythmia. The operative mortality was 5.1%. Overall, 29.0% of admissions had one or more arrhythmias the most common arrhythmia was nonsustained VT (18.0% of admissions), followed by nonsustained SVT (12.9% of admissions). Patients admitted to a pediatric CICU have a high incidence of arrhythmias, most likely associated with their underlying pathophysiology and to the breadth of medical and surgical interventions conducted. |
2,727 | Incremental net benefit in randomized clinical trials with quality-adjusted survival. | Owing to induced dependent censoring, estimating mean costs and quality-adjusted survival in a cost-effectiveness comparison of two groups using standard life-table methods leads to biased results. In this paper we propose methods for estimating the difference in mean costs and the difference in mean effectiveness, together with their respective variances and covariance in the presence of dependent censoring. We consider the situation in which the measure of effectiveness is either the probability of surviving a duration of interest or mean quality-adjusted survival time over a duration of interest. The methods are illustrated in an example using an incremental net benefit analysis. |
2,728 | Electrical injuries. | Electrical injury is a relatively infrequent but potentially devastating form of multisystem injury with high morbidity and mortality. Most electrical injuries in adults occur in the work-place, whereas children are exposed primarily at home. In nature, electrical injury occurs due to lightning, which also carries the highest mortality. The severity of the injury depends on the intensity of the electrical current (determined by the voltage of the source and the resistance of the victim), the pathway it follows through the victim's body, and the duration of the contact with the source of the current. Immediate death may occur either from current-induced ventricular fibrillation or asystole or from respiratory arrest secondary to paralysis of the central respiratory control system or due to paralysis of the respiratory muscles. Presence of severe burns (common in high-voltage electrical injury), myocardial necrosis, the level of central nervous system injury, and the secondary multiple system organ failure determine the subsequent morbidity and long-term prognosis. There is no specific therapy for electrical injury, and the management is symptomatic. Although advances in the intensive care unit, and especially in burn care, have improved the outcome, prevention remains the best way to minimize the prevalence and severity of electrical injury. |
2,729 | Atrial fibrillation: relation between clinical risk factors and transoesophageal echocardiographic risk factors for thromboembolism. | To correlate clinical risk factors for thromboembolism with transoesophageal echocardiography (TOE) markers of a thrombogenic milieu.</AbstractText>Clinical risk factors for thromboembolism and TOE markers of a thrombogenic milieu were assessed in consecutive patients with non-rheumatic atrial fibrillation. The following TOE parameters were assessed: presence of spontaneous echo contrast, thrombi, and left atrial appendage blood flow velocities. A history of hypertension, diabetes mellitus, or thromboembolic events, patient age > 65 years, and chronic heart failure were considered to be clinical risk factors for thromboembolism.</AbstractText>Tertiary cardiac care centre.</AbstractText>301 consecutive patients with non-rheumatic atrial fibrillation scheduled for TOE.</AbstractText>255 patients presented with clinical risk factors. 158 patients had reduced left atrial blood flow velocities, dense spontaneous echo contrast, or both. Logistic regression analysis showed that a reduced left ventricular ejection fraction and age > 65 years were the only independent predictors of a thrombogenic milieu (both p < 0.0001). The probability of having a thrombogenic milieu increased with the number of clinical risk factors present (p < 0.0001). 17.4% of the patients without clinical risk factors had a thrombogenic milieu whereas 41.2% of the patients presenting one or more clinical risk factors had none.</AbstractText>There is a close relation between clinical risk factors and TOE markers of a thrombogenic milieu. In addition, TOE examination allows for the identification of patients with a thrombogenic milieu without clinical risk factors.</AbstractText> |
2,730 | Genetics and arrhythmias. | The availability of chromosomal markers that span the human genome and improved high-throughput technology for genotyping and sequencing have led to major advances against genetic diseases. Genes have been identified for several disorders responsible for arrhythmias and sudden death. These genes all encode ion channels and are referred to as channelopathy genes. Congenital long QT syndrome is caused by mutations in genes encoding sodium or potassium channels. Brugada syndrome, only recently described, is due to mutations in a sodium channel and is an important cause of sudden death, particularly in Southeast Asia. Familial polymorphic ventricular tachycardia is due to a defect in the ryanodine receptor. A locus mapped to 10q32 is responsible for familial atrial fibrillation. Treatments based on knowledge of the molecular defect are being implemented for long QT syndrome and will probably provide paradigms for targeted treatment of acquired arrhythmias. |
2,731 | The automated external defibrillator: critical link in the chain of survival. | Sudden death due to ventricular fibrillation (VF) is the leading cause of death in the United States. Early defibrillation is the most important determinant of survival and is the key element in cardiopulmonary resuscitation. Obstacles to rapid defibrillation by trained emergency personnel persist, but the development of the automated external defibrillator (AED) promises to realize the goal of widespread early defibrillation and translate to an improved chance for survival for the cardiac arrest victim. Technological advancements have made the AED safe, easy to use, accurate, and effective in terminating VF. Use of the AED by trained nontraditional first responders (e.g., firefighters, police officers, flight crews) has improved survival rates in a variety of settings and forms the basis for public-access defibrillation. |
2,732 | Detection of malignant right coronary artery anomaly by multi-slice CT coronary angiography. | Coronary artery anomalies occur in 0.3-0.8% of the population and infer a high risk for sudden cardiac death in young adults. Diagnosis is usually established during coronary angiography, which is hampered by poor spatial visualization. Magnetic resonance imaging is an alternative, but it is not feasible in the presence of metal objects or claustrophobia. In this report, a 15-year-old boy experienced ventricular fibrillation and was successfully resuscitated. Cardiac catheterization was inconclusive, and pacemaker implantation prohibited the use of MR imaging. Multi-slice CT coronary angiography revealed a malignant anomalous right coronary artery. |
2,733 | Ventricular fibrillation: ablation of a trigger? | We report the case of a patient with recurrent ventricular fibrillation (VF) and no evidence of structural heart disease. VF was consistently initiated by a relatively early-coupled premature ventricular contraction with identical morphology on each occasion. Treatment with antiarrhythmic agents failed to suppress the arrhythmia. Electrophysiologic testing showed high-frequency potential at the earliest activation site, and radiofrequency ablation resulted in abolition of the ventricular ectopy with no further VF recurrence. Suppression of VF arising from focal triggers in patients with frequent ventricular ectopy and normal heart can be achieved with catheter ablation, but further studies are needed to evaluate the prevalence of such a mechanism. |
2,734 | Bundle branch reentrant tachycardia in patients with apparent normal His-Purkinje conduction: the role of functional conduction impairment. | His-Purkinje conduction delay, manifested by bundle branch block QRS complex configuration or by HV interval prolongation, is considered an essential condition for maintenance of bundle branch reentrant tachycardia (BBRT).</AbstractText>Of 178 patients with different types of ventricular tachycardia (VT), 13 were found to have BBRT as the underlying electrophysiologic mechanism. Of these 13 patients (9 men and 4 women; mean age 64 +/- 13 years), 6 had an HV interval < or = 55 msec (group A), and 7 had a prolonged HV interval (> 55 msec; group B) during sinus rhythm (SR). PR interval (169 +/- 32 vs 339 +/- 138 msec, P = 0.01) and QRS duration (116 +/- 17 vs 167 +/- 29 msec, P = 0.003) during SR were significantly shorter in group A than in group B. In group A, the HV interval was significantly longer during VT than during SR (73 +/- 18 vs 47 +/- 7 msec, P = 0.007). There were more patients with functional His-Purkinje block (split His potentials, a jump of HV interval induced by programmed atrial stimulation or burst pacing) or phase 3 block in group A than group B (6/6 patients vs 0/7 patients, P < 0.001). Successful ablation of the right bundle branch was performed in all 13 patients without deteriorating AV block. Two patients died in each group, and VTs (other than BBRT) or ventricular fibrillation were documented by ICD electrogram storages in 4 patients during follow-up of 27 +/- 17 months.</AbstractText>A prolonged HV interval during SR is not a prerequisite for BBRT. Functional His-Purkinje system abnormalities appear to be the electrophysiologic substrate for this specific type of BBRT.</AbstractText> |
2,735 | Intravenous adrenaline or vasopressin in sudden cardiac arrest: a literature review. | The chain of survival concept implies that provision of early access, early advanced care, including early intravenous drugs would improve survival in sudden cardiac arrest. Intravenous adrenaline (epinephrine) has been used as the drug of choice since 1906. What is the evidence for its effectiveness? Is vasopressin a better alternative?</AbstractText>We performed a systematic literature search in order to answer these questions. Evidence from the clinical trials that have been conducted on this subject was reviewed.</AbstractText>Experimental evidence confirms the beneficial effect adrenaline has on coronary perfusion pressure. However, adrenaline has not been shown conclusively to improve survival in clinical trials. Extensive trials have also failed to show any benefit of high-dose adrenaline over standard doses. Vasopressin seems to be more effective than adrenaline in animal studies for treatment of cardiac arrest due to resistant ventricular fibrillation. However, it has yet to be proven to be superior to adrenaline in clinical trials.</AbstractText>More research is needed into this area, especially randomised controlled trials studying the effectiveness of vasopressin. Meanwhile, in order to improve survival from sudden cardiac arrest, continuing effort should be made to achieve early initiation of cardiopulmonary resuscitation, early defibrillation and early advanced care.</AbstractText> |
2,736 | Bleeding and thromboembolic risks of internal cardioversion for persistent atrial fibrillation. | Although internal cardioversion is an effective method for converting AF the thromboembolic risk and bleeding complication of this procedure remains unclear. Retrospective analysis of the thromboembolic events and bleeding complications was performed in 114 consecutive patients (mean age 63 +/- 10 years, 91 men) who underwent internal cardioversion for persistent AF (mean AF duration 31 +/- 42 months). All patients received therapeutic warfarin for 3 weeks prior to the procedure, which was then replaced by periprocedural heparin therapy during internal cardioversion. The mean INR value before the internal cardioversion was 1.3 +/- 0.2. A total of 992 R wave synchronized shocks were delivered (mean 8.7 shocks/patients) without ventricular proarrhythmia. Successful internal cardioversion of AF was achieved in 100 (88%) patients. Two (2%) patients developed major bleeding complications with pericardial effusion after the procedure. Both of them subsided with conservative treatment. Minor bleeding with wound hematoma occurred in 8 (7%) of 114 after the procedure. Overall, there was no significant difference in the risk of procedure related complication between the use of heparin infusion and subcutaneous LMWH injection (6/78 [13%] vs 3/36 [8%], P = 0.9). No thromboembolic event was observed after 4 weeks of follow-up. In conclusion, the risk of thromboembolism after discontinuation of anticoagulation before the procedure is low in patients with persistent AF underwent internal cardioversion. However, the use of periprocedural heparin therapy was associated with an increase risk of procedure related bleeding complications. |
2,737 | Radiofrequency ablation of cardiac arrhythmias using a three-dimensional real-time position management and mapping system. | A recently developed three-dimensional real-time position management system (RPM) uses an ultrasound ranging technique that enables multiple distance measurements between two reference catheters and a mapping catheter each equipped with ultrasound transducers. In addition to three-dimensional representation of the catheters and ablation sites it displays real-time movements of catheters (including the tip and shaft). A recently released version of the system enables additional geometry reconstruction of the heart chamber and activation mapping. This study included 21 patients (mean age 59 +/- 14.5 years) referred for radiofrequency catheter ablation of various arrhythmias. Geometry was reconstructed by tracing the endocardial contour of the respective heart chambers. Global and local color coded activation maps were constructed to confirm the nature of arrhythmia and to guide ablation. Spontaneous or induced arrhythmias were typical atrial flutter (n = 8), atypical atrial flutter (n = 3), atrioventricular nodal reentrant tachycardia (n = 3), atrial tachycardia (n = 2), atrial fibrillation (n = 2), ventricular tachycardia (n = 2), and Wolff-Parkinson-White syndrome (n = 1). Geometry reconstruction and mapping of arrhythmias were possible in 20 of 21 patients. RPM-guided radiofrequency ablation was successful in 19 (95%) of 20 patients. Due to difficulties in steering the RPM mapping/ablation catheter, in 6 (28%) successfully mapped patients, radiofrequency ablation was performed using another catheter. In one patient, the RPM-guided map was inconclusive and in another patient, ablation failed due to multiple reentrant circuits. No complications were observed. In conclusion, the new RPM system enables geometry reconstruction and three-dimensional positioning of the ablation catheters, reconstruction of the activation maps, marking of anatomic structures and reproducible tracking of multiple ablation sites. The system could be used to guide radiofrequency ablation of atrial and ventricular arrhythmias. |
2,738 | Brugada syndrome with ventricular tachycardia and fibrillation related to hypokalemia. | A 60-year-old man with asymptomatic Brugada syndrome and neither a history of syncope nor family history of sudden death was admitted because of bronchial asthma. Serum potassium concentration was 3.8 mmol/L on admission, and decreased to 3.1 mmol/L on the 6th day, probably as a side effect of steroid therapy. The patient was found unconscious on the 7th day, and his serum potassium concentration was 3.4 mmol/L immediately after the episode. On the 8th day, the patient was again found unconscious, and polymorphic ventricular tachycardia and fibrillation (VT/VF) was documented on electrocardiographic (ECG) monitoring. The coved type of ST-segment elevation in leads V(1-3) was observed on the ECG after spontaneous recovery of sinus rhythm, and VT/VF associated with Brugada syndrome was diagnosed. The serum potassium concentration decreased to 2.9 mmol/L immediately after the episode, but QT prolongation was not observed during the clinical course. After the correcting the serum potassium concentration, there was no further recurrence of the malignant ventricular arrhythmia and syncope. An implantable cardioverter defibrillator was inserted to prevent sudden death. Hypokalemia that does not induce QT prolongation may contribute to the occurrence of VT/VF in Brugada syndrome. |
2,739 | Noncardioplegic surgery for ischemic mitral regurgitation. | Twenty-seven consecutive patients underwent surgery for ischemic mitral regurgitation (MR): papillary muscle rupture (1), papillary muscle dysfunction (11) and annular dilatation (15). The grade of MR was moderate or severe, and the ejection fraction (EF) was less than 30% in 8 patients (mean, 43%). Three cases were reoperation and 3 were emergencies. Under ventricular fibrillation (VF) and intermittent aortic cross-clamping at moderate hypothermia, coronary artery bypass grafting (CABG) was performed first, followed by the mitral procedure through a right-sided left atriotomy (repair 21, replacement 6) performed under VF with the heart perfused through the native coronary arteries and CABG grafts. Concomitant procedures were CABG (23), Dor's procedure (5), and tricuspid annuloplasty (3). In one reoperative case with cardiogenic shock, CABG was impossible because of dense adhesions and the patient died just after surgery (hospital mortality, 3.7%). Five patients required intra-aortic balloon pump (IABP) support intraoperatively, but none required prolonged (> or =7 days) inotropic support or IABP use, although the serum concentrations of creatine kinase and its myocardial fraction were elevated remarkably. Other morbid events were refractory ventricular arrhythmia in one case and stroke in another. Median duration of mechanical ventilation and intensive care unit stay was 8 h and 3 days, respectively. Mean EF at hospital discharge was 48%. The extended period of VF was not associated with unfavorable clinical outcomes. Noncardioplegic surgery for ischemic MR was carried out with acceptable mortality and morbidity, and can be a good alternative, especially when clamping the aorta is undesirable. |
2,740 | New ECG criteria for high-risk Brugada syndrome. | To identify high-risk patients with Brugada syndrome, the present study reviewed 60 standard 12-lead electrocardiograms from 60 patients collected by the Japanese Brugada syndrome registry. Under blinded conditions, the S wave of lead V(1) was measured from the tip of r to r', and the amplitude of the ST segment in lead V(2) was measured at 0.08 s from the J point. In patients with ventricular fibrillation (n=17), the S wave was significantly longer in V(1) (0.085+/-0.007 s vs 0.075+/-0.011 s, p=0.001), and ST segment elevation in V(2) was significantly greater (0.323+/-0.133 mV vs 0.236+/-0.129 mV, p=0.012) than in patients without fibrillation. An S wave width of 0.08 s or more in V(1) had a positive predictive value of 40.5% and negative predictive value of 100% for ventricular fibrillation, with 100% sensitivity. ST elevation of 0.18 mV or more in V(2) had a positive predictive value of 37.8% and a negative predictive value of 100% for ventricular fibrillation, with 100% sensitivity. Both an S wave width > or =0.08 s in V(1) and ST elevation > or =0.18 mV in V(2) were highly specific indicators of ventricular fibrillation and are proposed as new criteria for high-risk Brugada syndrome. |
2,741 | Rescue systemic thrombolysis during cardiopulmonary resuscitation. | The main goal of the cardiopulmonary resuscitation is good neurological outcome. The primary ischaemic insult initiates a multitude of coagulation and inflammatory cascades resulting in cytotoxic brain oedema, necrosis and apoptosis. Thrombolytic agents may have experimentally and clinically significant beneficial effects in non-traumatic cardiac arrest. Prospective clinical trials show that thrombolytic therapy combined with heparin is feasible, safe and effective during resuscitation. We demonstrate three cases of successful systemic thrombolysis during in hospital CPR in cancer patients. Two patients were successfully resuscitated from cardiac arrest with streptase bolus (500.000 IU) and infusion (100,000/hr). One patient with pulmonary embolism and gynecological bleeding were treated with bolus (10,000 IU) and infusion of heparin (1,000 IU/hr) and successfully resuscitated. We observed a very good neurological outcome in all 3 cases following rescue thrombolysis and standard CPR. Two patients were discharged from hospital in good neurological outcome. One patient died on ICU on 10th day due to myocardial re-infarction and biventricular failure. Systemic thrombolysis is safe and effective treatment modality during resuscitative efforts even in cancer patients. In oncological patients with dissemination and/or bleeding heparin therapy should be considered due to better clinical control. (Ref. 17.) |
2,742 | [Sudden cardiac death and inherited repolarization disorders]. | Repolarization disorders leading to ventricular tachyarrhythmias are common causes of sudden cardiac death. Two of the disorders have been recently described at the molecular level revealing gene mutations: long QT syndrome, characterized by a prolonged QT interval corrected for heart rate and high incidence of malignant ventricular tachycardia, mainly torsade de pointes, and Brugada syndrome characterized by a ST segment elevation in the right precordial leads (V1-V3), right bundle branch block and idiopathic ventricular fibrillation. This review outlines current understanding of molecular genetic basis and pathophysiology of these diseases. On the basis of these repolarization disorders lay ion channel dysfunctions. The new discoveries may in the future allow a better diagnosis by genetic testing and raise the possibility of effective treatment by means of the gene-specific therapy. |
2,743 | [Usefulness of Doppler echocardiography in the diagnosis of acute diastolic heart failure in the elderly]. | To evaluate the clinical usefulness of the determination of Doppler mitral inflow pattern and new combined indices using colour M mode velocity flow propagation (Vp) in the diagnosis of acute diastolic heart failure in the elderly.</AbstractText>Total serum protein concentration (P, g/l) and E/A, E/Vp and 1000/(2 x IRT + Vp) Doppler indices (E and A: mitral inflow peak velocities; IRT: isovolumic relaxation time) were measured at the time of therapy initiation in 94 patients with left ventricular ejection fraction > 50% (78 +/- 13 years), 56 with pulmonary edema and 38 patients with acute respiratory disease.</AbstractText>The feasibility was 73, 90 and 89% for E/A, E/Vp and 1000/(2 x IRT + Vp) respectively. The sensitivity, specificity and accuracy were 94-56-72%, 84-86-85% and 92-86-89% for E/A > or = 1, E/Vp > or = 2 and 1000/(2 x IRT + Vp) > or = 6 respectively in the diagnosis of pulmonary edema in patients with normal serum colloid osmotic pressure defined by P > or = 60 g/l, and 41-50-43%, 37-86-50% and 22-100-42% in patients with low colloid osmotic pressure (P < 60 g/l).</AbstractText>The mitral inflow measurement is limited in most of cases of acute diastolic heart failure in the elderly by confounding factors such as atrial fibrillation and normalised pattern. New combined Doppler indices are useful in these patients, however, their value must be interpreted according to the serum colloid osmotic status estimated by total serum protein concentration.</AbstractText> |
2,744 | Prevalence and prognostic value of exercise-induced ventricular arrhythmias. | The purpose of this study was to determine the prevalence and prognostic significance of exercise-induced ventricular arrhythmias (EIVAs) in patients referred for exercise testing, considering the arrhythmic substrate and exercise-induced ischemia.</AbstractText>EIVAs are frequently observed during exercise testing, but their prognostic significance is uncertain. The design of this study was a retrospective analysis of prospectively collected data, and it took place in 2 university-affiliated Veterans Affairs Medical Centers. Patients comprised 6213 consecutive males referred for exercise tests. We measured clinical exercise test responses and all-cause mortality after a mean follow-up of 6 +/- 4 years. EIVAs were defined as frequent premature ventricular contractions (PVCs) constituting >10% of all ventricular depolarizations during any 30 second electrocardiogram recording, or a run of > or =3 consecutive PVCs during exercise or recovery.</AbstractText>A total of 1256 patients (20%) died during follow-up. EIVAs occurred in 503 patients (8%); the prevalence of EIVAs increased in older patients and in those with cardiopulmonary disease, resting PVCs, and ischemia during exercise. EIVAs were associated with mortality irrespective of the presence of cardiopulmonary disease or exercise-induced ischemia. In those without cardiopulmonary disease, mortality differed more so later in follow up than earlier. In those without resting PVCs, EIVAs were also predictive of mortality, but in those with resting PVCs, poorer prognosis was not worsened by the presence of EIVAs.</AbstractText>Exercise induced ischemia does not affect the prognostic value of EIVAs, whereas the arrhythmic substrate does. EIVAs and resting PVCs are both independent predictors of mortality after consideration of other clinical and exercise-test variables. These findings are of limited clinical significance because of the modest change in risk and the lack of any established intervention. However, they explain some of the previous controversy and highlight the need to consider resting PVCs and follow-up duration in assessing the clinical implications of EIVAs.</AbstractText> |
2,745 | CPR for patients labeled DNR: the role of the limited aggressive therapy order. | Patients who sustain a cardiac arrest have a less than 20% chance of surviving to hospital discharge. Patients may request do-not-resuscitate (DNR) orders if they believe that their chances for a meaningful recovery after cardiopulmonary arrest are low. However, in some identifiable circumstances, cardiopulmonary resuscitation (CPR) has a higher chance of success and lower likelihood of neurologic impairment. The probability of survival from a cardiac arrest influences patients' wishes regarding resuscitation; thus, when CPR has a higher likelihood of success, patients' expressed preferences for treatment as contained within a DNR order may not accurately reflect their intended goals. Patients should be offered the option of consenting to CPR for "higher-success" situations, including a witnessed cardiopulmonary arrest in which the initial cardiac rhythm is ventricular tachycardia or fibrillation, cardiac arrest in the operating room, and cardiac arrest resulting from a readily identifiable iatrogenic cause. This new level of resuscitation could be called a "limited aggressive therapy" order. |
2,746 | Left ventricular function after monophasic and biphasic waveform defibrillation: the impact of cardiopulmonary resuscitation time on contractile indices. | Previous work has suggested that low-energy biphasic waveform defibrillation (BWD) is followed by less post-resuscitation left ventricular (LV) dysfunction when compared with higher-energy monophasic waveform defibrillation (MWD). To the best of the authors' knowledge, the effect of cardiopulmonary resuscitation (CPR) duration and total ischemia time on LV function after countershock, controlling for waveform type, has not been evaluated.</AbstractText>To determine the effect of CPR duration on LV function after MWD and BWD.</AbstractText>VF was electrically induced in anesthetized and instrumented swine. After 5 minutes of VF, the animals were randomized to MWD (n = 22) or one of two BWDs (n = 46). If countershock terminated VF but was followed by a nonperfusing rhythm, conventional manual CPR without drug therapy was performed until restoration of spontaneous circulation (ROSC), defined as a systolic arterial pressure >60 mm Hg for 10 minutes without vasopressor support. Systolic LV pressure (LVP), LV dP/dt (first derivative of pressure measured over time), and cardiac output (CO) were measured at intervals for 60 minutes postresuscitation. CPR times (times to ROSC) and hemodynamic variables for the three groups were compared. Multivariable linear regression was performed to assess the contribution of defibrillation waveform, total joules, and CPR time on LVP, LV dP/dt, and CO at 15, 30, and 60 minutes postresuscitation.</AbstractText>When analyzed as groups, significant differences in median number of shocks to terminate VF, total joules, or CPR time were not observed between waveform groups. Regression analysis demonstrated that increasing CPR time was associated with a significant effect on indices of LV function at 15 and 30 minutes postresuscitation. Global LV function was not influenced by waveform type or total joules.</AbstractText>Adjustment for CPR time, a determinant of total myocardial ischemia time, is necessary when defibrillation waveforms are compared for their effect on postresuscitation cardiac function and short-term outcome.</AbstractText> |
2,747 | Inappropriate shock delivery due to interference between a washing machine and an implantable cardioverter defibrillator. | Electromagnetic interference with implantable cardioverter defibrillators (ICD) can cause inappropriate delivery of therapies or temporary inhibition of ICD functions. The presented case describes electromagnetic interference between a washing machine and an ICD resulting in an inappropriate discharge of the device due to false detection of ventricular fibrillation. |
2,748 | Left ventricular dysfunction is associated with prolonged average ventricular fibrillation cycle length in patients with implantable cardioverter defibrillators. | In cellular studies, ventricular refractoriness (ERP) is prolonged in heart failure (CHF), but clinical evidence is lacking. The average ventricular fibrillation cycle length (VFCL) has been shown to correlate with local ERP. We hypothesized that the VFCL increases with left ventricular (LV) dysfunction. Therefore, we evaluated intracardiac VFCL recorded by implantable defibrillators (ICD) in patients with and without LV dysfunction.</AbstractText>We analyzed intracardiac VFCL recorded by sensing leads of Ventak MINI (Guidant) ICD in 49 patients (35 men; age 54 +/- 13 years; 25 (51%) with coronary artery disease; mean LV ejection fraction (EF) 41 +/- 17%, range 76-10) from the European Ventak MINI Investigator Group. No patients were receiving antiarrhythmic drugs, including beta-blockers. Mean and median VFCL were obtained at predischarge testing during first charge time (4.5 +/- 2.7 s, range 1.4-11).</AbstractText>Mean median VFCL was 186 +/- 21ms (range 150-230 ms). Patients with LVEF >/= 50% (n = 14) had shorter median VFCL than patients with LVEF < 50% (n = 35), (171 +/- 14 vs. 191 +/- 20 ms; p = 0.002). Median VFCL correlated with LVEF (r = -0.41; p = 0.003) and age (r = 0.28, p = 0.04), but was not significantly associated with charge time and defibrillation threshold at implant. Similar results occurred with mean VFCL. In multiple linear regression and correlation models, only LVEF% was a significant predictor (p < 0.05 for all models) of median VFCL.</AbstractText>LV dysfunction prolongs averaged VFCL in patients at risk for malignant ventricular arrhythmias who have implantable cardioverter defibrillators. This phenomenon might be related to alterations in the ventricular refractory period.</AbstractText> |
2,749 | A streamlined "3-catheter" approach in the electrophysiological study and radiofrequency ablation of narrow complex tachycardia. | Electrophysiological study (EPS) followed by radiofrequency (RF) ablation has emerged as the treatment of choice for symptomatic narrow complex tachycardia (NCT), for which purpose, 5 catheters are typically used (4 for the initial EPS and an additional one for the subsequent RF ablation). We describe an alternative, streamlined approach using only 3 catheters [2 standard (diagnostic) and 1 deflectable, thermistor tip (mapping)] as the standard configuration for EPS and RF ablation in patients with NCT but no pre-excitation on ECG.</AbstractText>Diagnosis was obtained in all 250 consecutive patients (mean age 45 years, 174 females): atrio-ventricular nodal re-entrant tachycardia (AVNRT) in 188 (75%), concealed accessory pathways (AP's) in 38 patients (15%), ectopic atrial tachycardia in 19 patients (8%), persistent junctional re-entrant tachycardia (PJRT) in 4 patients (2%) and atrial fibrillation in 1 patient. An additional diagnostic catheter was used for optimising atrial pacing in 3 patients and for ventricular pacing in concealed right postero-septal AP's in another 3. An additional mapping catheter was used in 31 patients with concealed left-sided AP's, 2 with multiple AP's and 1 with PJRT. Three patients had complications (1 pulmonary embolism, 1 pericardial effusion and 1 atrio-ventricular node block). Overall, the immediate success rate was 98% (224/229) with a recurrence rate of 4.4% (10/224), and the total success rate (with repeat RF ablation if necessary) was 99.2% (227/229) over a median follow-up period of 31.4 months. The average cost saving was US$474 per procedure. Procedure duration (2.0 +/- 0.1 hours), fluoroscopy time (13 +/- 1 minutes) and the number of radiofrequency applications (5.4 +/- 0.3) also compared favourably with values reported in the literature for RF ablation of AVNRT.</AbstractText>Compared to the conventional 5-catheter configuration for the combined EPS and RF ablation procedure in treatment of patients with NCT, the described 3-catheter configuration reduces cost, procedure duration and fluoroscopy time without compromising on success rate and safety. On these bases, we advocate its widespread adoption.</AbstractText> |
2,750 | Homicidal commotio cordis: the final blow in a battered infant. | This report describes in detail the occurrence of inflicted commotio cordis (cardiac concussion) in a previously abused 7-week-old. Though inflicted commotio cordis has been reported in three toddlers, this is the first report in a young infant.</AbstractText>Following documentation of abuse in a living child, the case of a death of a prior sibling--previously regarded as natural--was re-opened for further investigation. Original autopsy materials were reviewed, and the body of the deceased child was exhumed.</AbstractText>Exhumation and second autopsy documented more than 50 fractures in the deceased child. When re-interviewed, the children's father admitted to causing the injuries in both children, and gave a textbook description of commotio cordis as the mechanism of death in the fatal case.</AbstractText>Commotio cordis is a rare event in which a fatal dysrhythmia--usually ventricular fibrillation--is precipitated by a blow to the precordial chest. Previous reports have indicated that homicidal commotio cordis can occur in small children. This report demonstrates that commotio cordis can occur even in the very young, previously abused infant.</AbstractText>Copyright 2002 Elsevier Science Ltd.</CopyrightInformation> |
2,751 | A mathematical model of human atrioventricular nodal function incorporating concealed conduction. | This work develops a mathematical model for the atrioventricular (AV) node in the human heart, based on recordings of electrical activity in the atria (the upper chambers of the heart) and the ventricles (the lower chambers of the heart). Intracardiac recordings of the atrial and ventricular activities were recorded from one patient with atrial flutter and one with atrial fibrillation. During these arrhythmias, not all beats in the atria are conducted to the ventricles. Some are blocked (concealed). However, the blocked beats can affect the properties of the AV node. The activation times of the atrial events were regarded as inputs to a mathematical model of conduction in the AV node, including a representation of AV nodal concealment. The model output was compared to the recorded ventricular response to search for and identify the best possible parameter combinations of the model. Good agreement between the distribution of interbeat intervals in the model and data for durations of 5 min was achieved. A model of AV nodal behavior during atrial flutter and atrial fibrillation could potentially help to understand the relative roles of atrial input activity and intrinsic AV nodal properties in determining the ventricular response. |
2,752 | Reproduction of typical electrocardiographic findings of the Brugada syndrome using modified precordial leads. | We present a case of a patient with Brugada syndrome and aborted sudden cardiac death in whom the typical Brugada sign (coved-type ST segment elevation in the precordial leads V1 through V3) was always reproduced by the precordial leads recording on the second intercostal space even after the typical sign had disappeared. The finding indicates that recordings of precordial leads on the higher intercostal spaces are important to unmask the ST elevation in suspected patients with Brugada syndrome. |
2,753 | Acute hepatitis complicating intravenous amiodarone treatment. | We describe a case of acute hepatitis after a loading dose of intravenous amiodarone. An 83-year-old woman was admitted in emergency for recent-onset atrial fibrillation associated with left ventricular failure. Twenty-four hours after having started parenteral amiodarone, she developed biochemical alterations indicative of severe hepatic cytolysis associated with impairment of the synthetic capacity which rapidly reverted after suspension of the drug. No clinical sign or symptom of hepatopathy was noted except for mild icterus. A review of the literature regarding amiodarone-related hepatotoxicity is reported. |
2,754 | Clinical features and prognosis associated with a preserved left ventricular systolic function in a large cohort of congestive heart failure outpatients managed by cardiologists. Data from the Italian Network on Congestive Heart Failure. | The aim of this study was to evaluate the clinical characteristics, 1-year prognosis and therapeutic approach of heart failure with a preserved left ventricular systolic function in a large multicenter registry of patients referred to specialized heart failure clinics.</AbstractText>The study population consisted of 5164 outpatients (mean age 62 +/- 12 years, 78.8% male, 28.1% in NYHA functional class III-IV) with an available left ventricular ejection fraction (LVEF) measurement at the initial evaluation for enrollment in the Italian Network on Congestive Heart Failure. A 1-year follow-up was available for 2390 patients.</AbstractText>2859 out of 5164 patients (55.4%) had an LVEF < 35%, 1618 (31.3%) had an LVEF between 35 and 45%, and 687 patients (13.3%) had an LVEF > 45%. Patients with an LVEF > 45% were significantly older, more often female and presented a significantly higher prevalence of a hypertensive etiology, obesity and atrial fibrillation. The severity of the clinical picture, as indicated by a lower prevalence of NYHA class III-IV (17.2 vs 35.6%, p = 0.001) and a third heart sound (14.8 vs 33.5%, p = 0.001), was less in patients with an LVEF > 45%. The therapeutic approach differed significantly, with a larger use of calcium antagonists and beta-blockers in patients with an LVEF > 45%, while ACE-inhibitors, diuretics and digoxin were more often prescribed to those with an impaired LVEF. The 1-year mortality and morbidity (all cause and congestive heart failure worsening hospitalizations) were significantly lower in patients with a preserved left ventricular systolic function compared to those with left ventricular systolic dysfunction (8.9 vs 18.8% for mortality, p = 0.001, and 8.3 vs 16.5% for hospital readmissions due to worsening congestive heart failure, p = 0.001, respectively).</AbstractText>Patients with congestive heart failure and a preserved left ventricular systolic function seem to constitute a distinct population not infrequently presenting even in the clinical setting of specialized heart failure clinics. Further studies are needed to establish a definitive and standardized diagnosis and the most appropriate therapy for congestive heart failure with a normal LVEF.</AbstractText> |
2,755 | Transthoracic impedance does not decrease with rapidly repeated countershocks in a swine cardiac arrest model. | Successful defibrillation is dependent upon the delivery of adequate electrical current to the myocardium. One of the major determinant of current flow is transthoracic impedance. Prior work has suggested that impedance falls with repeated shocks during sinus rhythm. The purpose of this study was to evaluate changes in transthoracic impedance with repeated defibrillation shocks in an animal model of cardiac arrest due to ventricular fibrillation (VF).</AbstractText>VF was electrically induced in anesthetized swine. After 5 min of untreated VF, monophasic or biphasic waveform defibrillation was attempted using a standard sequence of 'stacked shocks' (200, 300, then 360 J, if necessary) administered via adhesive electrodes. If one of the first three shocks failed to convert VF, conventional CPR was initiated and defibrillation (360 J) attempted 1 min later. Strength-duration curves for delivered voltage and current were measured during each shock and transthoracic impedance calculated. Animals requiring a minimum of four shocks were selected for study inclusion. Impedance data from sequential shocks were analyzed using mixed linear models to account for the repeated-measures design and the variability of the initial impedance of individual animals.</AbstractText>Thirteen animals (monophasic waveform, n=7, biphasic waveform, n=6) required at least four shocks to terminate VF (range 4-6). Transthoracic impedance did not change from the first shock in the 13 animals (46+/-8 Omega) to the fourth shock (46+/-9 Omega). In animals receiving more than four shocks, transthoracic impedance likewise did not change significantly from the first to the last shock, which terminated VF. The lack of a significant change in impedance was also observed when animals were analyzed according to defibrillation waveform.</AbstractText>Transthoracic impedance does not change significantly with repeated shocks in a VF cardiac arrest model. This is likely due to the lack of reactive skin and soft tissue hyperemia and edema observed in non-arrest models.</AbstractText> |
2,756 | What happens when cardiac Na channels lose their function? 1--numerical studies of the vulnerable period in tissue expressing mutant channels. | The vulnerable period (VP) defines an interval during which premature impulses can trigger reentrant arrhythmias leading to ventricular fibrillation and sudden death. The mechanistic basis of the success or failure of impulse propagation during the VP remains unclear. Recent clinical reports of gene mutations, drugs and cardiac disease link a variety of often lethal conditions with loss of cardiac Na channel function (NaLOF) and reentrant proarrhythmia. We hypothesized that during the VP, the Na conductance at the stimulus site is graded and that NaLOF would favor reentry specifically by flattening this gradient, which would destabilize antegrade front formation.</AbstractText>Using numerical studies of propagation in a one-dimensional cable of ventricular cells, we identified the boundaries of the VP using paired (s1-s2) stimulation. We explored VP alterations associated with different NaLOF scenarios including reduced channel density, accelerated rate of inactivation, and prolonged recovery from inactivation.</AbstractText>Following the passage of a wave over the s2 site, a gradient in the restoration of Na channel conductance was demonstrated to exist during the VP. The VP boundaries coincided with different thresholds for stable retrograde and antegrade impulse propagation. Reducing channel density, accelerating inactivation and slowing the recovery from inactivation flattened the restoration gradient and extended the VP. VP extension was directly proportional to the time constant of Na channel recovery.</AbstractText>Mutations that accelerate inactivation, slow recovery from inactivation, or reduce Na channel density flatten the restoration gradient within the VP which prolongs the VP and increases the probability that a premature impulse will initiate reentry. These studies define a new mechanism that links alterations in Na channel function with conditions that enable premature excitation to generate proarrhythmia and sudden death.</AbstractText> |
2,757 | The effect of endocardial defibrillator shocks on basic atrial electrophysiology in man. Is post cardioversion atrial electrical 'remodelling' artefact? | To determine the effect of an endocardial DC shock on the basic electrophysiology of the human atrium if delivered in sinus rhythm.</AbstractText>A 5J endocardial R wave synchronized DC shock was delivered in 10 patients in stable sinus rhythm during ICD implantation for ventricular arrhythmias. There was no prior history of atrial fibrillation. Monophasic action potential duration (APD) and atrial effective refractory periods (AERP) were evaluated before, 1 min post DC shock, and 15 min post shock. These parameters were assessed at basic cycle lengths and at atrial paced cycle lengths of 600 ms and 400 ms at two right atrial sites; mid lateral right atrial wall (MRLA) and the right atrial appendage (RAA). There were no significant differences in APD 90, AERP or atrial refractory dispersion at any site or drive cycle length before, immediately after or 15 min after shock delivery.</AbstractText>There are no significant changes in basic electrophysiological parameters following a DC shock delivered in sinus rhythm in patients with no prior history of atrial fibrillation. This suggests that atrial electrical remodelling occurs as a result of atrial fibrillation and is unrelated to shock artefact.</AbstractText>Copyright 2003 The European Society of Cardiology.</CopyrightInformation> |
2,758 | Investigation of the potential of clozapine to cause torsade de pointes. | Antipsychotics are frequently associated with QTc interval prolongation, a proposed marker for vulnerability to fatal ventricular arrhythmias, e.g. torsade de pointes (TdP). Little has been published on this topic in relation to clozapine. The objectives of this review were to: (i) calculate the frequency of QTc interval prolongation, T-wave abnormalities, TdP, ventricular tachycardia/fibrillation and sudden unexplained death in patients treated with clozapine and thioridazine from clinical trial and post-marketing reports; (ii) to compare these data with published findings for haloperidol, risperidone, olanzapine, sertindole and ziprasidone; and (iii) to correlate these clinical data with results from preclinical tests presently considered to be of predictive value for a compound's potential to cause QTc interval prolongation and TdP. A review of the global Novartis databases for clozapine and thioridazine and a Medline/Internet search for information on these cardiac events and for preclinical effects on the human ether-a-go-go related gene channels, action potential duration, and QT interval changes produced by the selected antipsychotics were performed. The clozapine database (2.8 million patient-years spanning 27 years) demonstrated that at therapeutic doses all but three reports of QTc interval prolongation and both of TdP were confounded by relevant co-medication/comorbidity. The literature review revealed that all antipsychotics considered except clozapine induced TdP and/or QTc interval prolongation at therapeutic doses. Preclinical in vitro tests appear to overestimate the risk of clozapine, haloperidol and risperidone to prolong QTc interval in patients and underestimate such a risk for sertindole and ziprasidone. Extrapolation of in vitro results to clinical events requires qualified interpretation. |
2,759 | Transition from ventricular fibrillation to ventricular tachycardia: a simulation study on the role of Ca(2+)-channel blockers in human ventricular tissue. | We study the effect of blocking the L-type Ca(2+)-channel on fibrillation in simulations in two-dimensional (2D) isotropic sheets of ventricular tissue and in a three-dimensional anisotropic anatomical model of human ventricles, using a previously developed model of human ventricular cells. Ventricular fibrillation (VF) was obtained as a result of spiral wave breakup and consisted of a varying number of chaotically wandering wavelets activating tissue at a frequency of about 6.0 Hz. We show that blocking the Ca(2+)-current by 75% can convert ventricular fibrillation into a periodic regime with a small number of stable spiral waves, ranging from six in 2D sheets of 25 x 25 cm to a single spiral in the anatomical model of human ventricles. The dominant frequency during this process changed to about 10.0 Hz in the 2D simulations, but to only 5.0 Hz in the whole heart simulations where a single spiral wave anchored around an anatomical obstacle. We show that the observed effects were due to a flattening of the electrical restitution curve, which prevented the generation of wave breaks and stabilized the activation patterns. |
2,760 | Rapid on-site defibrillation versus community program. | For patients who suffer out-of-hospital cardiac arrest, the time from collapse to initial defibrillation is the single most important factor that affects survival to hospital discharge. The purpose of this study was to compare the survival rates of cardiac arrest victims within an institution that has a rapid defibrillation program with those of its own urban community, tiered EMS system.</AbstractText>A logistic regression analysis of a retrospective data series (n = 23) and comparative analysis to a second retrospective data series (n = 724) were gathered for the study period September 1994 to September 1999. The first data series included all persons at Casino Windsor who suffered a cardiac arrest. Data collected included: age, gender, death/survival (neurologically intact discharge), presenting rhythm (ventricular fibrillation (VF), ventricular tachycardia (VT), or other), time of collapse, time to arrival of security personnel, time to initiation of cardiopulmonary resuscitation (CPR) prior to defibrillation (when applicable), time to arrival of staff nurse, time to initial defibrillation, and time to return of spontaneous circulation (if any). Significantly, all arrests within this series were witnessed by the surveillance camera systems, allowing time of collapse to be accurately determined rather than estimated. These data were compared to those of similar events, times, and intervals for all patients in the greater Windsor area who suffered cardiac arrest. This second series was based upon the Ontario Prehospital Advanced Life Support (OPALS) Study database, as coordinated by the Clinical Epidemiology Unit of the Ottawa Hospital, University of Ottawa.</AbstractText>The Casino Windsor had 23 cases of cardiac arrests. Of the cases, 13 (56.5%) were male and 10 (43.5%) were female. All cases (100%) were witnessed. The average of the ages was 61.1 years, of the time to initial defibrillation was 7.7 minutes, and of the time for EMS to reach the patient was 13.3 minutes. The presenting rhythm was VF/VT in 91% of the case. Fifteen patients were discharged alive from hospital for a 65% survival rate. The Greater Windsor Study area included 668 cases of out-of-hospital cardiac arrest: Of these, 410 (61.4%) were male and 258 (38.6%) were female, 365 (54.6%) were witnessed, and 303 (45.4%) were not witnessed. The initial rhythm was VF/VT was in 34.3%. Thirty-seven (5.5%) were discharged alive from the hospital.</AbstractText>This study provides further evidence that PAD Programs may enhance cardiac arrest survival rates and should be considered for any venue with large numbers of adults as well as areas with difficult medical access.</AbstractText> |
2,761 | Resuscitation for patients with out-of-hospital cardiac arrest: Singapore. | To evaluate characteristics and outcome of out-of-hospital cardiac arrest (OHCA) patients presenting to the Emergency Department (ED), and to examine factors that could be used to determine to prolong or abort resuscitation for these patients.</AbstractText>All OHCA patients presenting to the ED were studied over a three-month period from November 2001 through January 2002. Patient with traumatic cardiac arrest were excluded. Data were collected from the ambulance case records, ED resuscitation charts, and the ED Very High Frequency (VHF) radio case-log sheet. Information collected included the patient's demographic characteristics, timings (time from call to ambulance arrival on scene, time from arrival at scene to departure from scene, time from scene to arrival in the ED) recorded in the pre-hospital setting, the outcome of the resuscitation, and the final outcome for patients who survived ED resuscitation.</AbstractText>Ninety-three non-traumatic patients with an OHCA were studied during the three-month period. Of the 93 patients, 15 (16.1%) survived ED resuscitation, and one survived to hospital discharge. There were no statistically significant differences for age, race, or gender with regards to the outcome of the resuscitation. The initial cardiac rhythms were asystole (65), pulseless electrical activity (21), and ventricular fibrillation (7). Fourteen (15%) received bystander cardiopulmonary resuscitation (CPR). All seven patients with return of spontaneous circulation (ROSC) on arrival in the ED survived ED resuscitation. The ambulance took an average of 11.80 +/- 3.36 minutes for the survivors and 11.8 +/- 4.22 minutes for the non-survivors from the time of call to get to these patients. The average of the scene times was 12.5 +/- 4.61 minutes for the survivors and 12.0 +/- 4.02 minutes for the non-survivors. Transport time from the scene to the ED took an average of 39.1 +/- 8.32 minutes for the survivors and 37.2 +/- 9.00 minutes for the non-survivors.</AbstractText>The survival rate for patients with OHCA after ED resuscitation is similar to the results from other studies. There is a need to increase the awareness and delivery of basic life support by public education. Automatic External Defibrillators (AED) should be available widely to ensure that the chance of early defibrillation is increased. Prolonged resuscitation efforts appear to be futile for OHCA patients if the time from cardiac arrest until arrival in the ED is > or = 30 minutes coupled with no ROSC, and if continuous asystole has been documented for > 10 minutes.</AbstractText> |
2,762 | Electrocardiographic effects of intravenous cocaine: an experimental study in a canine model. | Cocaine abuse causes cardiac dysfunction. Acute intravenous administration of cocaine may lead to development of severe arrhythmias, conduction abnormalities, ST-T changes, and sudden death. Understanding arrhythmogenesis due to cocaine may provide a therapeutic approach to reduce morbidity and mortality. We studied the arrhythmogenic activity and other electrocardiographic abnormalities resulting from an intravenous bolus of cocaine. Baseline and postanesthetic electrocardiographic findings were compared with those after administration of intravenous bolus of various doses of cocaine hydrochloride in 20 dogs. The study was done in three phases (phase I: low dose of cocaine [1 mg/kg, 15 experiments]; phase II: medium dose [2 mg/kg, 30 experiments]; and phase III: high dose [5-7 mg/kg, 10 experiments]). Plasma levels of cocaine were estimated. The low dose induced sinus bradycardia, sinus arrhythmia, atrial ectopic, wandering pacemaker, unifocal ventricular premature contractions, and ventricular couplets. The medium dose generated moderately severe arrhythmias that were of supraventricular origin. Atrial flutter and atrial fibrillation were observed in two experiments each. Ventricular arrhythmias were manifested as unifocal, multifocal, interpolated ventricular premature contractions as well as bigeminy, trigeminy, couplets, and salvos. The high dose of 5-7 mg/kg increased electrocardiographic intervals and caused ST-segment elevation as well as serious life-threatening arrhythmias. Three of the dogs developed sustained ventricular tachycardia followed by ventricular flutter-fibrillation and death. |
2,763 | Prolongation of LAS40 (duration of the low amplitude electric potential component (<40 microV) of the terminal portion of the QRS) induced by isoproterenol in 11 patients with Brugada syndrome. | The electrophysiological mechanism of Brugada syndrome is unclear, but transmural dispersion of repolarization in the right ventricle is believed to be the most likely mechanism. On the other hand, the presence of a conduction delay region is considered to be related to the occurrence of ventricular fibrillation; that is, a relationship between the presence of a ventricular late potential (LP) and arrhythmogenic right ventricular cardiomyopathy. In this study, the LP from signal-averaged electrocardiography during isoproterenol (ISP) administration in patients with Brugada syndrome is discussed. The subjects were 11 patients with Brugada syndrome and 6 healthy individuals. In all subjects, the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS(40)), duration of the low amplitude electric potential component (40 microV) of the terminal portion of the QRS (LAS(40)), and time duration of the fQRS-LAS(40) difference were compared between when ISP was prescribed and when it was not. During ISP administration, a peculiar response, which resulted in an LAS(40) prolongation, was observed in the patients with Brugada syndrome. With ISP, the fQRS remained unchanged, but the RMS(40) and the fQRS-LAS(40) decreased. Consequently another 3 patients with a positive LP were diagnosed using the ordinary standard because of the administration of ISP. We believe that the low-amplitude component was unmasked by shortening of the high-amplitude component. In patients with Brugada syndrome, a conduction delay in the ventricle may be present and may be related to the occurrence of ventricular fibrillation. |
2,764 | Protective effects of SEA0400, a novel and selective inhibitor of the Na+/Ca2+ exchanger, on myocardial ischemia-reperfusion injuries. | The Na(+)/Ca(2+) exchanger (NCX) is involved in myocardial ischemia-reperfusion injuries. We examined the effects of 2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400), a potent and selective inhibitor of NCX, on myocardial ischemia-reperfusion injury models. In canine cardiac sarcolemmal vesicles and rat cardiomyocytes, SEA0400 potently inhibited the Na(+)-dependent 45Ca(2+) uptake with an IC(50) value of 90 and 92 nM, compared with 2-[2-[4-(4-nitrobenzyloxy)phenyl]isothiourea (KB-R7943, 7.0 and 9.5 microM), respectively. In rat cardiomyocytes, SEA0400 (1 and 3 microM) attenuated the Ca(2+) paradox-induced cell death. In isolated rat Langendorff hearts, SEA0400 (0.3 and 1 microM) improved the cardiac dysfunction induced by low-pressure perfusion followed by normal perfusion. In anesthetized rats, SEA0400 (0.3 and 1 mg/kg, i.v.) reduced the incidence of ventricular fibrillation and mortality induced by occlusion of the left anterior descending coronary artery followed by reperfusion. These results suggest that SEA0400 is a most potent NCX inhibitor in the heart and that it has protective effects against myocardial ischemia-reperfusion injuries. |
2,765 | [Anticoagulant treatment of patients with atrial fibrillations: dependent on age and other risk factors for thromboembolism]. | Atrial fibrillation is a common arrhythmic disorder which is becoming increasingly prevalent among the elderly. Atrial fibrillation is an independent risk factor for ischaemic stroke. Patients with hypertension, heart failure, diabetes, age older than 65 years, previous thromboembolisms, left atrial enlargement and left ventricular dysfunction have an increased risk. Coumarins (with a target international normalised ratio (INR) of 2.0 to 3.0) are the treatment of first choice in patients with atrial fibrillation. In young patients without additional risk factors, acetyl salicylic acid provides sufficient protection. The management of anticoagulant therapy during electric cardioversion in the acute phase of an ischaemic stroke and during elective surgical interventions, is still a subject of clinical research. |
2,766 | [The added value of a structured evaluation of patients with vascular disease]. | In 3 patients, 2 women aged 21 and 34 years and a man aged 56 years, with complaints related to wide-ranging and extensive vascular conditions, an organ-specific diagnostic approach and treatment did not lead to the correct diagnosis of the underlying clinical condition. Hereafter a structured, partly protocol-based approach was started which considered the entire vascular system and risk factors for vascular disease. The youngest women died a few years later due to ventricular fibrillation, while the two other patients were assisted in reducing those risk factors that could be influenced. As a result, the planned bypass operation was no longer necessary for the male patient. A structured evaluation by a multidisciplinary team can optimise the care of these patients. The basis of such a team consists of a vascular specialist and vascular nurse-practitioner, both of whom should have specific knowledge of risk factors, aetiology, life style intervention and treatment of these disorders. |
2,767 | Induction of ventricular fibrillation in Brugada syndrome by site-specific right ventricular premature depolarization. | This patient was a 50-year-old man. Oral pilsicainide unmasked a Brugada-type ECG abnormality and self-terminating polymorphic VT was repetitively induced. The polymorphic VT always developed following a specific ventricular premature complex showing a left bundle branch block pattern suggesting a limited origin in the right ventricle. |
2,768 | [Effect of amiodarone on autonomic status and its efficacy in the treatment of different variants of paroxysmal atrial fibrillation]. | Association of autonomic status and efficacy of therapy with amiodarone was studied in 90 patients with paroxysmal atrial fibrillation of ischemic (n=45, mean age 62 years) and nonischemic (n=45, mean age 38 years) origin. Autonomic status was assessed by measurement of heart rate variability. Electrophysiological and echocardiographical studies were also conducted before and after 4 weeks of amiodarone therapy. Treatment with amiodarone was accompanied by substantial lowering of the tone of autonomic nervous system in patients with adrenergic type of paroxysmal atrial fibrillation while there was no dynamics of parasympathetic tone in patients with vagal or mixed types. Positive association between amiodarone therapy and decrease of left atrial dimension and improvement of left ventricular contractility was also observed. It was concluded that the use of amiodarone was justified in adrenergic but not in vagal or mixed variants of paroxysmal atrial fibrillation. |
2,769 | [Long QT interval syndrome]. | Long QT interval syndrome is a cardiac disorder associated with fatal ventricular arrhythmias (torsade de pointes and ventricular fibrillation). Timely diagnosis and adequate treatment may decrease mortality due this syndrome. The present review summarizes results of recent studies of etiology, pathogenesis, clinical picture, diagnosis and treatment of the long QT syndrome. |
2,770 | Maintained benefits and improved survival of dynamic cardiomyoplasty by activity-rest stimulation: 5-year results of the Italian trial on "demand" dynamic cardiomyoplasty. | Latissimus dorsi (LD) muscular degeneration caused by continuous electrical stimulation has been the main cause of the poor results of dynamic cardiomyoplasty (DCMP) and its exclusion from the recent international guidelines on heart failure. To avoid full transformation of the LD and to improve results, a new stimulation protocol was developed; fewer impulses per day are delivered, providing the LD wrap with daily periods of rest ("demand" stimulation), based on a heart rate cut-off. The aim of this work is to report the results at 5 years of follow-up of the Italian Trial of Demand Dynamic Cardiomyoplasty and to discuss their impact on the destiny of this type of cardiac assistance.</AbstractText>Twelve patients with dilated myocardiopathy (M/F=11/1, mean age 58.2+/-5.8 years, sinus rhythm/atrial fibrillation=11/1) were submitted during the period 1993-1996 to DCMP and at different intervals to demand protocol. Clinical, echocardiographic, mechanographic and cardiac invasive assessments were scheduled before initiating the demand protocol and during the follow-up at 0, 6 and every 12 months.</AbstractText>The mean duration of follow-up was 40.2+/-13.8 months (range 18-64). There were no perioperative deaths. The demand stimulation protocol showed a decrease in 5 years in New York Health Association (NYHA) class (3.17+/-0.38-1.67+/-0.77, P=0.0001), an improvement of left ventricular ejection fraction (22.6+/-4.38-32.0+/-7.0, P<0.001), a 5-year actuarial survival of 83.3% (one patient was switched to heart transplantation programme due to clinical worsening and another one died of massive pulmonary embolism).</AbstractText>Demand DCMP maintains over time LD muscular properties, enhances clinical benefits and improves survival of DCMP, thus reopening the debate whether this type of treatment should be considered in patients with end-stage heart failure.</AbstractText> |
2,771 | [The Wearable Cardioverter Defibrillator (WCD) for the prevention of sudden cardiac death -- a single center experience]. | The Wearable Cardioverter Defibrillator (WCD) is an external defibrillator that automatically detects and treats ventricular tachyarrhythmias without the need for assistance from a bystander while at the same time allowing the patient to ambulate freely. The main components of the system are the defibrillator unit and a chest belt with electrodes for arrhythmia detection and therapy delivery. Between December 1998 and October 2001, 84 patients used the device at our institution. The majority of patients had a history of acute myocardial infarction or coronary artery bypass surgery with an increased risk for sudden cardiac death or were awaiting heart transplantation. During a mean follow-up of 116+/-90 days, 7 episodes of ventricular tachyarrhythmias were detected and terminated successfully by the WCD in 5 patients. In 9720 days, there was one inappropriate shock due to oversensing of electrical noise. Four patients died during follow-up; none of them had a cardiac arrest while wearing the device. Five patients were excluded because of irregularities in device use. An ICD was implanted in 24 patients at the end of the follow-up period. The WCD is effective in detecting and treating ventricular tachyarrhythmias in patients with an intermittently increased risk for sudden cardiac death. Further use of the system in larger patient populations is needed to confirm its safety and cost effectiveness. |
2,772 | The effect of isoproterenol on the class III effect of azimilide in humans. | Many class III antiarrhythmic agents lose efficacy under beta-adrenergic stimulation and at high heart rates (reverse rate dependence). This effect is thought to be due to selective blockade of the rapidly (I(Kr)), but not the slowly (I(Ks)), activating component of the delayed inward rectifier potassium current. Azimilide is an investigational class III antiarrhythmic agent that blocks both IKr and IKs.</AbstractText>We investigated the electrophysiologic effect of azimilide with and without beta-adrenergic stimulation in humans. Right ventricular effective refractory period at cycle lengths of 600 and 400 milliseconds and monophasic right ventricular action potential duration at 90% repolarization at cycle lengths of 250, 300, 400, 500 and 600 milliseconds were measured in 13 patients at baseline. Isoproterenol was then infused to increase the heart rate to 125% of baseline, and the pacing protocol was repeated. Patients then received, in a single-blind randomized manner, azimilide dihydrochloride (4.5 mg/kg intravenous loading dose followed by 0.625 mg/kg/h) plus either isoproterenol at the previous dose, or saline. After measurements were taken, treatment groups were crossed over, the azimilide infusion was continued and the procedure repeated.</AbstractText>Azimilide significantly (P < 0.05) prolonged monophasic action potential duration compared to baseline at all cycle lengths except for the 250 millisecond cycle length. In the presence of isoproterenol, azimilide maintained its class III effect, prolonging the action potential duration at 90% repolarization by a mean of 8.7 +/- 3.9 milliseconds, (3.7 +/- 1.7%), whereas isoproterenol alone shortened the action potential duration at 90% repolarization by -2.6 +/- 3.2 milliseconds (-1.2 +/- 1.4%) (P = 0.0051). Isoproterenol alone shortened the right ventricular effective refractory period by -13.6 +/- 3.4 milliseconds, whereas with isoproterenol in the presence of azimilide, the right ventricular effective refractory period was essentially unaffected (-1.4 +/- 3.4 milliseconds, P = 0.0085).</AbstractText>Azimilide maintained its class III effect in the presence of isoproterenol and at increased heart rates, suggesting that IKs block may be of particular benefit in these circumstances.</AbstractText> |
2,773 | Noninvasive estimation of both systolic and diastolic pulmonary artery pressure from Doppler analysis of tricuspid regurgitant velocity spectrum in patients with chronic heart failure. | Noninvasive estimation of pulmonary artery systolic and diastolic pressures usually requires the investigation of both tricuspid and pulmonary regurgitant jets and an estimate of right atrial pressure. A new, noninvasive method to obtain pulmonary diastolic pressure (based on the hemodynamic demonstration that right ventricular systolic pressure and pulmonary artery diastolic pressure are equal at the time of pulmonary valve opening) from the analysis of tricuspid regurgitation alone has been described in a small cohort of patients. We sought to verify the accuracy of this method in a large population of patients with heart failure.</AbstractText>An estimate of pulmonary artery diastolic pressure was obtained by transposing the pulmonary opening time (from the onset of the R wave on the electrocardiographic tracing to the beginning of pulmonic forward flow on Doppler examination) onto the tricuspid regurgitant velocity curve and calculating the pulmonary artery diastolic pressure value as the pressure gradient between the right ventricle and right atrium at this time. The study group included 86 consecutive patients (64 men, aged 52 +/- 11 years) with heart failure (New York Heart Association class > or =II, 94%) who were in stable clinical condition with a chiefly idiopathic (57%), ischemic (24%), or other form (13%) of dilated cardiomyopathy. Noninvasive, right-sided pressures were compared with invasive measurements obtained during right heart catheterization performed within 24 hours. The Bland and Altman graphic method was used together with the calculation of the Lin concordance correlation coefficient and its 95% CI to assess the agreement between hemodynamic and echocardiographic measurements.</AbstractText>Catheter-derived pulmonary artery systolic pressure ranged from 8 to 119 mm Hg (mean 42 +/- 21 mm Hg), pulmonary artery diastolic pressure from 1 to 59 mm Hg (mean 20 +/- 11 mm Hg), and right atrial pressure from -5 to 20 mm Hg (mean 6 +/- 5 mm Hg). Tricuspid regurgitation was detected in 75 of 86 patients (87%). Pulmonary artery systolic pressure ranged from 13 to 110 mm Hg (mean 44 +/- 21 mm Hg); the pressure gradient between the right ventricle and right atrium at time t of the pulmonary valve opening on the tricuspid regurgitation velocity curve was measurable in 70 of 75 (93%) cases and ranged from 3.5 to 64 mm Hg (mean 22 +/- 11 mm Hg). Good agreement was observed not only for pulmonary artery systolic pressure but also for pulmonary artery diastolic pressure, based on the analysis of the tricuspid regurgitation velocity jet, with a slight difference between measurements (-1.8 and 0.1, respectively), no evident pattern of point scattering, and a high concordance correlation coefficient that was elicited by the virtually total overlapping of lines on the graph. Overall results were not significantly different whether patients with depressed right ventricular function (right ventricular ejection fraction < or =35%), with a tricuspid regurgitation grade > or =2 and atrial fibrillation were included in the analysis.</AbstractText>The narrow paired difference for the estimate of pulmonary artery systolic pressure and the even better difference for pulmonary artery diastolic pressure using the tricuspid regurgitation velocity curve analysis indicates that this new method reliably estimates invasive right-sided pressures over a wide range of pressure values in patients with heart failure. The overall good correlation with invasive values indicates that Doppler examination of tricuspid regurgitation alone may provide a simple and comprehensive new method for the noninvasive evaluation of right ventricular and pulmonary hemodynamics in patients with heart failure.</AbstractText> |
2,774 | Fixed-energy biphasic waveform defibrillation in a pediatric model of cardiac arrest and resuscitation. | For adults, 150-J fixed-energy, impedance-compensating biphasic truncated exponential (ICBTE) shocks are now effectively used in automated defibrillators. However, the high energy levels delivered by adult automated defibrillators preclude their use for pediatric patients. Accordingly, we investigated a method by which adult automated defibrillators may be adapted to deliver a 50-J ICBTE shock for pediatric defibrillation.</AbstractText>Prospective, randomized study.</AbstractText>A university-affiliated research institution.</AbstractText>Domestic piglets.</AbstractText>We initially investigated four groups of anesthetized mechanically ventilated piglets weighing 3.8, 7.5, 15, and 25 kg. Ventricular fibrillation was induced with an AC current delivered to the right ventricular endocardium. After 7 mins of untreated ventricular fibrillation, a conventional manual defibrillator was used to deliver up to three 50-J ICBTE shocks. If ventricular fibrillation was not reversed, a 1-min interval of precordial compression preceded a second sequence of up to three shocks. The protocol was repeated until spontaneous circulation was restored, or for a total of 15 mins. In a second set of experiments, we evaluated a 150-J biphasic adult automated defibrillator that was operated in conjunction with energy-reducing electrodes such as to deliver 50-J shocks. The same resuscitation protocol was then exercised on piglets weighing 3.7, 13.5, and 24.2 kg.</AbstractText>All animals were successfully resuscitated. Postresuscitation hemodynamic and myocardial function quickly returned to baseline values in both experimental groups, and all animals survived.</AbstractText>An adaptation of a 150-J biphasic adult automated defibrillator in which energy-reducing electrodes delivered 50-J shocks successfully resuscitated animals ranging from 3.7 to 25 kg without compromise of postresuscitation myocardial function or survival.</AbstractText> |
2,775 | Stroke volumes generated by precordial compression during cardiac resuscitation. | To quantitate stroke volumes generated by precordial compression during cardiopulmonary resuscitation and to determine their relationship to coronary perfusion pressure and the success of resuscitation.</AbstractText>Prospective, observational animal study.</AbstractText>Medical research laboratory in a university-affiliated research and educational foundation.</AbstractText>Domestic pigs.</AbstractText>Ventricular fibrillation was electrically induced in 25 anesthetized male domestic pigs. After an interval of 7 mins, electrical defibrillation was attempted. Failing to reverse ventricular fibrillation in each instance, precordial compression was begun coincident with mechanical ventilation.</AbstractText>Stroke volumes were computed from differences between diastolic and systolic areas of the left ventricle by utilizing transesophageal echocardiography. Both stroke volumes and coronary perfusion pressure were consistently greater in successfully resuscitated animals. Progressive decreases in stroke volumes during precordial compression were predictive of unsuccessful resuscitation. A linear correlation between stroke volume and coronary perfusion pressure (r =.70) was documented.</AbstractText>These observations support the concept that stroke volumes generated by precordial compression are quantitatively related to the coronary perfusion pressure and to the success of cardiopulmonary resuscitation.</AbstractText> |
2,776 | Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals. | In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired. |
2,777 | Catecholaminergic polymorphic ventricular tachycardia: electrocardiographic characteristics and optimal therapeutic strategies to prevent sudden death. | To investigate the clinical outcome, ECG characteristics, and optimal treatment of catecholaminergic polymorphic ventricular tachycardia (CPVT), a malignant and rare ventricular tachycardia.</AbstractText>Questionnaire responses and ECGs of 29 patients with CPVT were evaluated. Mean (SD) age of onset was 10.3 (6.1) years.</AbstractText>The initial CPVT manifestations were syncope (79%), cardiac arrest (7%), and a family history (14%). ECGs showed sinus bradycardia and a normal QTc. Mean heart rate during CPVT was 192 (30) beats/min. Most cases were non-sustained (72%), but 21% were sustained and 7% were associated with ventricular fibrillation. The morphology of CPVT was polymorphic (62%), polymorphic and bidirectional (21%), bidirectional (10%), or polymorphic with ventricular fibrillation (7%). There was 100% inducement of CPVT by exercise, 75% by catecholamine infusion, and none by programmed stimulation. No late potential was recorded. Onset was in the right ventricular outflow tract in more than half the cases. During a follow up of 6.8 (4.9) years, sudden death occurred in 24% of the patients, 7% of whom had anoxic brain damage. Autosomal dominant inheritance was seen in 8% of the patients' families. beta Blockers completely controlled CPVT in only 31% of cases. Calcium antagonists partially suppressed CPVT in autosomal dominant cases.</AbstractText>CPVT may arise in certain distinct areas but the prognosis is poor. The onset of CPVT may be an indication for an implanted cardioverter-defibrillator.</AbstractText> |
2,778 | Factors associated with survival to hospital discharge among patients hospitalised alive after out of hospital cardiac arrest: change in outcome over 20 years in the community of Göteborg, Sweden. | To describe the change in survival and factors associated with survival during a 20 year period among patients suffering from out of hospital cardiac arrest and being hospitalised alive.</AbstractText>All patients hospitalised alive in the community of Göteborg after out of hospital cardiac arrest between 1 October 1980 and 1 October 2000 were included.</AbstractText>Patient data were prospectively computerised with regard to factors at resuscitation. Data on medical history and hospitalisation were retrospectively recorded. Patients were divided into two groups (the first and second 10 year periods).</AbstractText>Community of Göteborg, Sweden.</AbstractText>5505 patients suffered from cardiac arrest during the time of the survey. Among them 1310 patients (24%) were hospitalised alive. Survival (discharged alive) was 37.5% during the first part and 35.1% during the second part (NS). The following were independent predictors of an increased chance of survival: ventricular fibrillation/tachycardia as the first recorded rhythm (odds ratio (OR) 3.46, 95% confidence interval (CI) 2.36 to 5.07); witnessed arrest (OR 2.50, 95% CI 1.52 to 4.10); bystander initiated cardiopulmonary resuscitation (OR 2.00, 95% CI 1.42 to 2.80); the patient being conscious on admission to hospital (OR 6.43, 95% CI 3.61 to 11.45); sinus rhythm on admission to hospital (OR 1.53, 95% CI 1.12 to 2.10); and treatment with lidocaine in the emergency department (OR 1.64, 95% CI 1.16 to 2.31). The following were independent predictors of a low chance of survival: age > 70 years (median) (OR 0.65, 95% CI 0.47 to 0.88); atropine required in the emergency department (OR 0.35, 95% CI 0.16 to 0.75); and chronic treatment with diuretics before hospital admission (OR 0.59, 95% CI 0.43 to 0.81).</AbstractText>There was no improvement in survival over time among initial survivors of out of hospital cardiac arrest during a 20 year period. Major indicators for an increased chance of survival were initial ventricular fibrillation/tachycardia, bystander cardiopulmonary resuscitation, arrest being witnessed, and the patient being conscious on admission. Major indicators for a lower chance were high age, requirement for atropine in the emergency department, and chronic treatment with diuretics before cardiac arrest.</AbstractText> |
2,779 | Changing incidence of out-of-hospital ventricular fibrillation, 1980-2000. | Recent reports from 2 European cities and an earlier observation from Seattle, Wash, suggest that the number of patients treated for out-of-hospital ventricular fibrillation (VF) has declined.</AbstractText>To analyze the incidence of cardiac arrest and to examine relationships among incidence, sex, race, age, and first identified cardiac rhythm in Seattle.</AbstractText><AbstractText Label="DESIGN, SETTING, AND PATIENTS" NlmCategory="METHODS">Population-based study of all cardiac arrest cases with presumed cardiac etiology who received advanced life support from Seattle Fire Department emergency medical services during specified periods between 1979 and 2000. United States Census data for Seattle in 1980, 1990, and 2000 were used to determine incidence rates for treated cardiac arrest with adjustments for age and sex.</AbstractText>Changes in incidence of cardiac arrest and initial recorded cardiac rhythm.</AbstractText>The adjusted annual incidence of cardiac arrest with VF as the first identified rhythm decreased by about 56% from 1980 to 2000 (from 0.85 to 0.38 per 1000; relative risk [RR], 0.44; 95% confidence interval [CI], 0.37-0.53). Similar reductions occurred in blacks (54%; RR, 0.45; 95% CI, 0.26-0.79) and whites (53%; RR, 0.47; 95% CI, 0.38-0.58) and was most evident in men (57%; RR, 0.43; 95% CI, 0.35-0.53), in whom the baseline incidence was relatively high. When all treated arrests with presumed cardiac etiology were considered, that incidence decreased by 43% (RR, 0.58; 95% CI, 0.49-0.67) in men but negligibly in women, for whom a relatively low incidence of VF also declined but was offset by more cases with asystole or pulseless electrical activity.</AbstractText>We observed a major decline in the incidence of out-of-hospital VF and in all cases of treated cardiac arrest presumably due to heart disease in Seattle. These changes likely reflect the national decline in coronary heart disease mortality.</AbstractText> |
2,780 | [Acute pancreatitis caused by atrial fibrillation?]. | We report three male patients who had atrial fibrillation with a rapid and irregular ventricular rate, aged 60, 69 and 70 years, respectively, in whom development of acute pancreatitis occurred simultaneously with other ischaemic events.</AbstractText>One of these patients simultaneously suffered from a transient ischaemic attack (TIA), another developed a stroke and an infarction of the spleen, while the third one had a splenic infarction and an embolism in the region of the mesenteric arteries. Two patients had paroxysmal atrial fibrillation, while the third suffered from ischemic cardiomyopathy with chronic atrial fibrillation.</AbstractText>Oedematous pancreatitis occurred in one patient while, in the two others, the diagnosis of severe necrotizing pancreatitis was made.</AbstractText>Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice and a recognized risk factor for the development of peripheral embolism, which often takes the form of an ischaemic stroke. It is a major cause of stroke, especially in the elderly. Because of the simultaneous occurrence of thromboembolic events in all three patients, an ischaemic cause for the acute pancreatitis can be assumed with a high degree of probability. This is one of the first reports of acute ischaemic pancreatitis probably caused by microembolization secondary to atrial fibrillation. Because of the relatively frequent occurrence of atrial fibrillation, this factor deserves increased attention in the differential diagnosis of supposedly idiopathic pancreatitis.</AbstractText> |
2,781 | Brugada syndrome: a decade of progress. | The Brugada syndrome has gained wide recognition throughout the world and today is believed to be responsible for 4% to 12% of all sudden deaths and approximately 20% of deaths in patients with structurally normal hearts. The incidence of the disease is on the order of 5 per 10 000 inhabitants and, apart from accidents, is the leading cause of death of men under the age of 50 in regions of the world where the inherited syndrome is endemic. This minireview briefly summarizes the progress made over the past decade in our understanding of the clinical, genetic, cellular, ionic, and molecular aspects of this disease. |
2,782 | [Psychological stress and sudden death]. | Recent studies provide relevant evidence that psychological stress significantly influences the pathogenesis of sudden cardiac death. Psychological stress expresses a situation of imbalance, derived from a real or perceived disparity between environmental demands and the individual's ability to cope with these demands. A situation of psychological stress may include different components: personality factors and character traits, anxiety and depression, social isolation and acute or chronic adverse life events. In particular, it has been documented that a sudden extremely hard event, such as an earthquake or a war strike, can significantly increase the incidence of sudden death. Nevertheless, each one of these factors, if not present, can balance a partially unfavorable situation; this overview suggests a multifactorial situation where almost all elements are present and in which the relative influence of each one varies according to the individual examined. Sudden death occurs when a transient disruption (such as acute myocardial ischemia, platelet activation or neuroendocrine variations), occurring in a patient with a diseased myocardium (such as one with a post-necrotic scar or hypertrophy), triggers a malignant arrhythmia. Psychological stress acts at both levels: by means of a "chronic" action it contributes to create the myocardial background, while by means of an acute action it can create the transient trigger precipitating sudden death. In the chronic action two possible mechanisms can be detected: the first is a direct interaction, which contributes to cause a hypertension status or to exacerbate coronary atherosclerosis consequent to endothelial dysfunction; the second one acts through adverse health behaviors, such as a poor diet, alcohol consumption or smoking. In case of acute psychological stress, the mechanisms involved are mainly the ability to trigger myocardial ischemia, to promote arrhythmogenesis, to stimulate platelet function, and to increase blood viscosity. Finally, some individuals have a sympathetic nervous system hyper-responsitivity, manifesting as exaggerated heart rate and blood pressure responses which result in accelerated atherosclerosis. |
2,783 | Detection of enteroviral RNA (poliovirus types 1 and 3) in endomyocardial biopsies from patients with ventricular tachycardia and survivors of sudden cardiac death. | The purpose of this study was to determine the prevalence of enteroviral infection in the myocardium of consecutive patients with serious ventricular arrhythmias by using a reverse transcription nested PCR followed by direct DNA sequencing. After exclusion of coronary heart disease, right ventricular endomyocardial biopsies were obtained from 32 consecutive patients with a history of ventricular tachycardia or sudden cardiac death. Control biopsies were obtained from 36 subjects with no history of viral myocarditis, dilated cardiomyopathy, ventricular tachycardia or recent infection. Enteroviral genome was found in endomyocardial biopsies from 4/32 patients (12.5%), 2 with a history of ventricular tachycardia and 2 with a history of ventricular fibrillation. Three of these 4 enteroviral RNA-positive patients had dilated cardiomyopathy and the other had normal cardiac geometry and ventricular function. In the latter and in 1 patient with enteroviral-positive dilated cardiomyopathy, an active inflammatory process in the myocardium was found by means of immunohistology. Enteroviral RNA in the myocardium of 3 patients had the highest homology to poliovirus type 1 (strain CHAT 10A-11) and in the other was similar to poliovirus type 3 (strain P3/119). All control samples were negative for enteroviral RNA. In summary, these findings raise the possibility that enteroviruses, such as poliovirus types 1 and 3, may be involved in the pathogenesis of ventricular tachycardia and sudden cardiac death. |
2,784 | New concepts in transthoracic defibrillation. | The transition of biphasic waveforms from ICDs to external defibrillators constitutes a significant technological advances for transthoracic defibrillation. Impedance compensation has enabled the delivery of defibrillating current adapted to each patient and each shock in the same patient. Optimally designed biphasic waveforms have been shown clinically to have greater efficacy in the termination of VF when compared with monophasic waveforms, and because peak current delivery is less, these waveforms are likely to be less injurious to myocardial function. Advances in the understanding of the mechanisms of fibrillation and defibrillation have identified the electrophysiologic events that initiate and sustain VF and the effects of defibrillation shocks on those events. Definition of the role of VEP and postshock excitation has clarified the mechanisms by which shocks can either fail or succeed. The ability of the second phase of optimal biphasic waveform shocks to exploit recruited sodium channels in negatively polarized areas and thus induce rapid propagation of postshock excitation assures uniform depolarization and prevention of re-entry. This appears to be the major mechanism of greater efficacy of biphasic waveforms. It seems certain that continuing investigation of virtual electrodes will enhance our understanding of defibrillation and optimal waveforms. At the same time, much more needs to be known regarding translation of these experimental observations to mechanisms of defibrillation in human hearts with long-standing underlying structural heart disease, which often arises of multiple factors. This represents a major challenge in defibrillation research. |
2,785 | Midterm clinical results in myocardial revascularization using the radial artery. | The aim of this study was to evaluate the immediate and midterm results of coronary artery bypass grafting with the radial artery (RA) as a conduit.</AbstractText>Two hundred forty-one patients underwent myocardial revascularization using the RA. In 78.5% of patients, three coronary vessels were involved, and in 25% of patients, the left main coronary artery was involved. The mean (+/- SD) preoperative ejection fraction was 58 +/- 13%.</AbstractText>The RA was implanted on branches of the circumflex artery in 81% of the cases, and the left internal mammary artery was implanted on the left anterior descending artery in 94% of patients. Total arterial myocardial revascularization was performed in 58% of patients.</AbstractText>The in-hospital mortality rate was 0.8%. Two patients had acute myocardial infarction, and three patients experienced a transient low-cardiac output syndrome. We reviewed the records of all 171 patients who had undergone at least 6 months of follow-up after surgery. The late mortality rate in this group was 0.6% (one patient died 2 months after surgery because of cardiocirculatory arrest due to untreatable ventricular fibrillation). At a mean follow-up time of 545 +/- 253 days, two patients showed class 3 residual angina according to the Canadian Cardiovascular Society (CCS) guidelines. One patient required another hospital admission 6 months after undergoing surgery for PTCA/stenting on a circumflex artery that had not previously undergone bypass. The second patient, 8 months after undergoing coronary artery bypass grafting, underwent angiography and stenting on a stenosed anastomosis of a posterolateral branch of the circumflex artery that previously had been bypassed with the right internal mammary artery.</AbstractText>The routine use of the RA for coronary bypass grafting is a safe surgical technique, providing excellent clinical mid-term results in terms of cardiac event-free expectancy.</AbstractText> |
2,786 | Cardiac troponin T and cardiac enzymes after external transthoracic cardioversion of ventricular arrhythmias in patients with coronary artery disease. | Serum levels of cardiac troponins after external cardioversion (ECV) for atrial fibrillation and atrial flutter are widely investigated, and no increases in cardiac troponin T (cTnT) levels have been reported. However, the effect of ECV on cardiac enzyme release may depend on the type of arrhythmias. Furthermore, ventricular tachycardia (VT) or ventricular fibrillation (VF) could cause release of cardiac enzymes after ECV due to underlying myocardial ischemia, myocardial dysfunction, or more pronounced hemodynamic deterioration during arrhythmia.</AbstractText>The purpose of this study was to determine whether direct current (DC) shock may increase cardiac enzyme levels in patients with coronary artery disease undergoing ECV for VT or VF, so that diagnosis of acute myocardial infarction, which initially presents with VT or VF, can be excluded.</AbstractText>We obtained measurement of cTnT, total creatine kinase (CK), and CK MB isoenzyme (CK-MB) activity before and after ECV in 27 patients (mean +/- SD age, 62 +/- 13 years) with induced VT or VF (22 patients) who required ECV during provocative electrophysiologic testing and who underwent ECV due to VT (5 patients) in the cardiology department. Blood samples were drawn before, and 4 h, 8 h, and 24 h after ECV. The total energy used was 630 +/- 375 J (range, 200 to 1,280 J). CK levels rose to the upper limit of reference range in seven patients (26%), and CK-MB activity was higher than the normal reference range in five patients (19%) after ECV. In contrast, cTnT concentrations remained within the normal range (< 0.1 micro g/L) in all patients. Peak CK and CK-MB activity levels strongly correlated with the total energy delivered.</AbstractText>Elevation of cTnT level after an urgent DC shock strongly indicates the diagnosis of acute myocardial infarction presented with life-threatening arrhythmias, rather than myocardial damage caused by ECV.</AbstractText> |
2,787 | Is it safe to program a long tachycardia detection interval? | Implantable cardioverter defibrillator (ICD) therapy is used frequently in patients with "slow" ventricular tachycardia (VT). Hence, the tachycardia detection interval is programmed within the range of the physiologic heart rate, but this may cause serious problems. If a fast VT is converted to sinus tachycardia with a cycle length shorter than the tachycardia detection interval, the episode is not terminated and the success counter is not reset. If this happens repeatedly, therapies will be exhausted without termination of the episode. If VT recurs within such an episode, it will not be treated. This report describes a patient who died suddenly in a scenario similar to the one described. Although all documented VT/ventricular fibrillation episodes were terminated by the device, the episode was not terminated because of the ongoing supraventricular tachycardia. Therefore, no further therapies were available and the patient probably died of fast untreated VT. Programming of a long tachycardia detection interval is dangerous in currently available ICDs. |
2,788 | Inducible ventricular flutter and fibrillation predict for arrhythmia occurrence in coronary artery disease patients presenting with syncope of unknown origin. | Ventricular fibrillation and ventricular flutter (cycle length < or = 230 msec) induced at electrophysiologic studies are thought to be nonspecific findings in patients presenting with syncope of unknown origin. However, there are limited data on the prognosis of these patients in long-term follow-up.</AbstractText>We followed 274 consecutive patients with coronary artery disease presenting with syncope or presyncope who underwent electrophysiologic studies from January 1992 to June 1999 and assessed the risk of subsequent arrhythmias stratified by the electrophysiologic result at the time of their presentation with syncope. Ventricular fibrillation was induced in 23 patients (8%); ventricular flutter in 24 (9%), sustained ventricular tachycardia in 41 (15%); and nonsustained ventricular tachycardia 42 (15%). In 37 +/- 25 months of follow-up, there have been ventricular arrhythmias in 34 patients, including 3 (13%) of 23 who had induced ventricular fibrillation, and 7 (30%) of 24 with induced ventricular flutter, compared to 13 (32%) of 41 with sustained ventricular tachycardia, 7 (17%) of 42 with nonsustained ventricular tachycardia, and only 4 (3%) of 144 noninducible patients (P < 0.001 for induced ventricular fibrillation and ventricular flutter vs noninducible patients). The inducibility of ventricular fibrillation and ventricular flutter were independent risk factors for arrhythmia occurrence in follow-up.</AbstractText>Ventricular fibrillation and ventricular flutter induced at electrophysiologic studies have prognostic significance for arrhythmia occurrence in patients presenting with syncope. These induced arrhythmias may not be as nonspecific as previously thought and treatment should be considered for these patients.</AbstractText> |
2,789 | Advanced rhythm discrimination for implantable cardioverter defibrillators using electrogram vector timing and correlation. | Discrimination of ventricular and supraventricular arrhythmias remains one of the major challenges for appropriate implantable defibrillator (ICD) therapy delivery. The electrogram vector timing and correlation (VTC) algorithm was developed for such rhythm discrimination. The VTC algorithm differentiates normally conducted supraventricular beats from abnormally conducted ventricular beats by comparing the timing and correlation of rate and shock channel electrograms.</AbstractText>Rate and shock channel electrograms of sinus rhythm and induced arrhythmias were collected from 93 patients during ICD placement. The algorithm was developed using data from 50 patients and prospectively tested in a software model with the remaining 43 patients. A sinus rhythm reference was formed by averaging complexes of the shock channel signal aligned by the peak amplitude of the rate channel. Eight features measuring the amplitude and timing of shock channel signal characteristics were extracted from the reference for comparison. When a high-rate rhythm was detected, the VTC algorithm computed the correlation of the arrhythmia complex features with the reference. Rhythms with a sufficient number of uncorrelated beats were classified as ventricular tachycardia (VT). In a dual-chamber implementation, the VTC algorithm is integrated with ventricular and atrial rate comparison (V>A) and stability above an atrial fibrillation rate threshold. The test set consisted of 117 arrhythmias. Dual-chamber sensitivity was 100% (81/81 VT) and specificity was 97% (35/36 supraventricular tachycardia). Single-chamber analysis demonstrated 99% sensitivity and 97% specificity.</AbstractText>The VTC algorithm demonstrated high sensitivity and specificity in discriminating between ventricular and supraventricular arrhythmias.</AbstractText> |
2,790 | Ischemic preconditioning suppresses ventricular tachyarrhythmias after myocardial revascularization. | Ventricular fibrillation (VF) and tachycardia (VT) are the common and potential life-threatening complications after CABG. Ischemic preconditioning (IP) has been proved effective in reducing ischemia reperfusion arrhythmia in animals and humans. Whether IP is effective in suppressing postoperative VF/VT in patients with CABG has not been studied.</AbstractText>Eighty-six patients with CABG with stable and unstable 3-vessel disease were equally randomly assigned into an IP and a control group. The patients who received IP received 2 periods of 2-minute ischemia followed by 3-minute reperfusion. Twenty-four-hour electrocardiographic data were collected. IP resulted in fewer cases of VF after declamping (48.8% versus 79.1% in IP and control, P=0.004) and a shorter VF period (2.28+/-0.44 versus 4.41+/-0.51 minutes, P=0.002). The episodes of VT were significantly reduced in patients in the IP group during early reperfusion and 24 hours after reperfusion (0.65+/-0.16 versus 3.71+/-0.46, P=0.000 and 0.07+/-0.04 versus 2.12+/-1.41, P=0.002, respectively). De novo sustained VT occurred in 3 control patients as against none in the IP group after surgery. As a result, IP significantly curtailed the mechanical ventilation period and reduced the need for inotropes.</AbstractText>IP significantly reduced postoperative VF/VT in patients with CABG with 3-vessel disease. Suppression of VT during early reperfusion and 24 hours after reperfusion suggests early and delayed IP phenomena in patients undergoing CABG surgery.</AbstractText> |
2,791 | Cardiac arrhythmia classification using autoregressive modeling. | Computer-assisted arrhythmia recognition is critical for the management of cardiac disorders. Various techniques have been utilized to classify arrhythmias. Generally, these techniques classify two or three arrhythmias or have significantly large processing times. A simpler autoregressive modeling (AR) technique is proposed to classify normal sinus rhythm (NSR) and various cardiac arrhythmias including atrial premature contraction (APC), premature ventricular contraction (PVC), superventricular tachycardia (SVT), ventricular tachycardia (VT) and ventricular fibrillation (VF).</AbstractText>AR Modeling was performed on ECG data from normal sinus rhythm as well as various arrhythmias. The AR coefficients were computed using Burg's algorithm. The AR coefficients were classified using a generalized linear model (GLM) based algorithm in various stages.</AbstractText>AR modeling results showed that an order of four was sufficient for modeling the ECG signals. The accuracy of detecting NSR, APC, PVC, SVT, VT and VF were 93.2% to 100% using the GLM based classification algorithm.</AbstractText>The results show that AR modeling is useful for the classification of cardiac arrhythmias, with reasonably high accuracies. Further validation of the proposed technique will yield acceptable results for clinical implementation.</AbstractText> |
2,792 | [Pathogenetic assessment of cardiac arrhythmia and myocardial ischemia in hemodynamic stroke]. | 330 patients with ischemic stroke entered the trial. They were divided into two groups: 72 (21.8%) patients with hemodynamic stroke (group 1) and the rest 258 (78.2%) patients with other pathogenetic subtypes of stroke (group 2). Heart rhythm and myocardial ischemia were studied using ECG and Holter monitoring. Electrocardiographically, hemodynamic stroke is characterized by frequent ventricular extrasystole, sick sinus syndrome and transient atrioventricular block of the second and third degree with pauses 2 s and longer, ventricular fibrillation and painless myocardial ischemia. Perpetual and paroxysmal atrial fibrillation and paroxysmal ventricular tachycardia are not pathognomonic for hemodynamic stroke though these disorders can be also considered as independent pathogenetic factors of hemodynamic cerebral focal lesion. |
2,793 | [Isolated and asymptomatic Brugada syndrome. A case report]. | The case report of a 32-year-old man with a Brugada syndrome is presented. He was asymptomatic and without familial history of sudden death or syncope. Diagnosis criteria for Brugada syndrome were 1--a pattern of right bundle branch block and ST-segment elevation in leads V1 and V2 on the ECG, 2--no cardiac structural anomalies. Symptomatic patients with this electrical anomaly are at high risk of sudden death and need an automatic implantable defibrillator. The outcome and the treatment of asymptomatic patients are a matter of debate and are discussed in this report. |
2,794 | SNP S1103Y in the cardiac sodium channel gene SCN5A is associated with cardiac arrhythmias and sudden death in a white family. | Cardiac arrhythmias cause 400 000 sudden deaths annually in the United States alone. Mutations in the cardiac sodium channel gene SCN5A on chromosome 3p21 cause cardiac arrhythmias and sudden death. In this study, we define an SCN5A mutation, S1103Y, in a white family associated with syncope, ventricular fibrillation, and sudden death. A very recent study reported the same mutation in 13.2% of African Americans, but not in the white population. Our study shows that mutation S1103Y does exist in the white population, and it is associated with a considerable risk of syncope, ventricular arrhythmia, ventricular fibrillation, and sudden death in this population. |
2,795 | A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. | Maintenance of sinus rhythm is the main therapeutic goal in patients with atrial fibrillation. However, recurrences of atrial fibrillation and side effects of antiarrhythmic drugs offset the benefits of sinus rhythm. We hypothesized that ventricular rate control is not inferior to the maintenance of sinus rhythm for the treatment of atrial fibrillation.</AbstractText>We randomly assigned 522 patients who had persistent atrial fibrillation after a previous electrical cardioversion to receive treatment aimed at rate control or rhythm control. Patients in the rate-control group received oral anticoagulant drugs and rate-slowing medication. Patients in the rhythm-control group underwent serial cardioversions and received antiarrhythmic drugs and oral anticoagulant drugs. The end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, implantation of a pacemaker, and severe adverse effects of drugs.</AbstractText>After a mean (+/-SD) of 2.3+/-0.6 years, 39 percent of the 266 patients in the rhythm-control group had sinus rhythm, as compared with 10 percent of the 256 patients in the rate-control group. The primary end point occurred in 44 patients (17.2 percent) in the rate-control group and in 60 (22.6 percent) in the rhythm-control group. The 90 percent (two-sided) upper boundary of the absolute difference in the primary end point was 0.4 percent (the prespecified criterion for noninferiority was 10 percent or less). The distribution of the various components of the primary end point was similar in the rate-control and rhythm-control groups.</AbstractText>Rate control is not inferior to rhythm control for the prevention of death and morbidity from cardiovascular causes and may be appropriate therapy in patients with a recurrence of persistent atrial fibrillation after electrical cardioversion.</AbstractText>Copyright 2002 Massachusetts Medical Society</CopyrightInformation> |
2,796 | A comparison of rate control and rhythm control in patients with atrial fibrillation. | There are two approaches to the treatment of atrial fibrillation: one is cardioversion and treatment with antiarrhythmic drugs to maintain sinus rhythm, and the other is the use of rate-controlling drugs, allowing atrial fibrillation to persist. In both approaches, the use of anticoagulant drugs is recommended.</AbstractText>We conducted a randomized, multicenter comparison of these two treatment strategies in patients with atrial fibrillation and a high risk of stroke or death. The primary end point was overall mortality.</AbstractText>A total of 4060 patients (mean [+/-SD] age, 69.7+/-9.0 years) were enrolled in the study; 70.8 percent had a history of hypertension, and 38.2 percent had coronary artery disease. Of the 3311 patients with echocardiograms, the left atrium was enlarged in 64.7 percent and left ventricular function was depressed in 26.0 percent. There were 356 deaths among the patients assigned to rhythm-control therapy and 310 deaths among those assigned to rate-control therapy (mortality at five years, 23.8 percent and 21.3 percent, respectively; hazard ratio, 1.15 [95 percent confidence interval, 0.99 to 1.34]; P=0.08). More patients in the rhythm-control group than in the rate-control group were hospitalized, and there were more adverse drug effects in the rhythm-control group as well. In both groups, the majority of strokes occurred after warfarin had been stopped or when the international normalized ratio was subtherapeutic.</AbstractText>Management of atrial fibrillation with the rhythm-control strategy offers no survival advantage over the rate-control strategy, and there are potential advantages, such as a lower risk of adverse drug effects, with the rate-control strategy. Anticoagulation should be continued in this group of high-risk patients.</AbstractText>Copyright 2002 Massachusetts Medical Society</CopyrightInformation> |
2,797 | [Hardware implementation in VT/VF detection algorithms for AED (automatic external defibrillators)]. | The automatic external defibrillator (AED) should carry out the diagnosis of the patient in a cardiac emergency when medical professionals are not present. The decision about defibrillation should be made without the help of first responder. To fulfill these requirements special algorithms are needed. In this article the structure of such an algorithm and also hardware implementation problems are described. |
2,798 | [Autoantibodies: new upstream targets of paroxysmal atrial fibrillation in patients with congestive heart failure]. | The clinical implications of autoantibodies (Abs) were investigated as upstream indicators of paroxysmal atrial fibrillation in patients with congestive heart failure.</AbstractText>Circulating Abs against myosin (M-Abs) detected by immunofluorescence, Abs against beta 1-adrenergic receptors (Beta 1-Abs) detected by enzyme-linked immunosorbent assay (ELISA), and Abs against NA-K-ATPase (NKA-Abs) detected by ELISA were screened in 95 congestive heart failure patients with < or = 45% left ventricular ejection fraction (coronary artery disease, n = 48; dilated cardiomyopathy, n = 47) and 48 age-matched control patients with hypertension. No patient received antiarrhythmic therapy. All patients were enrolled with angiotensin converting enzyme inhibitors in the chronic stable state. Relationship of the presence of paroxysmal atrial fibrillation to other clinical variables were assessed by 48-hour Holter monitoring.</AbstractText>No control patient had Abs. However, M-Abs, Beta 1-Abs, and NKA-Abs were detected in 22%, 26% and 16% of patients with congestive heart failure (coronary artery disease; 8%, 10%, and 4%, dilated cardiomyopathy; 36%, 43%, and 28%, respectively). Paroxysmal atrial fibrillation was more frequent in patients with dilated cardiomyopathy than in those with coronary artery disease (47% vs 15%, p < 0.01). Multivariate analysis suggested that NKA-Abs was an independent risk factor for the occurrence of paroxysmal atrial fibrillation (p < 0.01), although there were no differences in other clinical factors: age, sex, New York Heart Association functional class, concomitant medication, left ventricular ejection fraction, left atrial diameter, severity of mitral regurgitation, serum potassium, plasma norepinephrine, and atrial natriuretic peptide concentration.</AbstractText>Autoantibodies against sarcolemmal Na-K-ATPase were closely related to the occurrence of paroxysmal atrial fibrillation in patients with congestive heart failure, so an autoimmune process may be an upstream factor in atrial fibrillation.</AbstractText> |
2,799 | [Use of semi-automatic defibrillators outside the hospital]. | With an annual incidence of 1 to 2@1000 and a rate of survival without complication of 2%, sudden death outside hospital constitutes a serious public health problem in France. Ventricular fibrillation (VF) is responsible for more than three quarters of these deaths. The rate of survival is inversely proportional to the duration of VF making early defibrillation a strong link in the chain of survival. The chances of survival are much greater if the cardio-respiratory arrest occurs with a witness, basic first aid is started rapidly, diagnosis of VF is made quickly and the first shock is delivered as soon as possible. These last two criteria are being met more often since the advent of the semi-automatic defibrillator (SAD) and its availability to first line rescuers. The SAD is a light and compact defibrillator capable of automatic analysis of the electrocardiographic trace, charging if it detects ventricular tachycardia (VT) or VF. By analysing the QRS amplitude, its slope, its morphology, its spectral density and the duration of the isoelectric line, the SAD is capable of recognising VF with a sensibility of 98% and a specificity of 93%. The shock, however, is only delivered with a manoeuvre from the operator. The SAD memorizes both the rhythmic event treated and certain parameters relating to its use. During the last decade, the SAD has benefited from the technological evolutions of the implantable automatic defibrillator, with the introduction of a biphasic shock. The use of a biphasic shock allows reduction in the minimal defibrillation charge and thus lightens the apparatus and increases the number of shocks which the SAD can deliver on a charged battery. In authorizing paramedics by statute to use the SAD, it has been possible to reduce the interval from alert to first delivered shock to 8 minutes although it would be 10 minutes if the medical team was awaited, and to obtain a survival rate without complication of 6.3%. The progress achieved by the use of the SAD in the chain of survival cannot be denied. However, to surpass automatic defibrillation and widen the use of defibrillators to an informed and motivated public would certainly bring our results closer to those obtained in America where the survival rate reaches 30% in the best cases; subject to widespread first aid training for the population. |
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