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Biomedical subjects

P Denes

Publications and source records attributed to P Denes.

At least 37 records · Page 2Linked to original sources
PubMed1990

Permanent pacemaker placement in chronic atrial fibrillation associated with intermittent AV block and cerebral symptoms.

We examined the hypothesis that a greater than or equal to 2 second pause detected on 24-hour Holter monitoring in patients with persistent atrial fibrillation and complaints of syncope or dizziness lacked sufficient specificity to warrant implantation of a permanent pacemaker. We retrospectively reviewed cases from our 24-hour electrocardiographic (Holter) monitoring data base. A total of 411 consecutive Holter monitoring records demonstrating persistent atrial fibrillation obtained during a 5-year period (1982 to 1987) were examined. One hundred and five (26%) patients had cerebral symptoms (dizziness or syncope) as a primary indication for monitoring 80 (76%) patients were identified with documented ventricular pauses of greater than or equal to 2 seconds. Three hundred and six patients (74%) underwent 24-hour monitoring without cerebral symptoms as an indication and 209 (68%) patients had greater than or equal to 2-second pauses. Clinical information was available in 164 (50 symptomatic and 114 asymptomatic) patients. There were no significant differences in the clinical or Holter findings between the two groups. Of the 50 symptomatic patients, 15 (30%) underwent permanent pacemaker placement and the remaining 35 (70%) were managed conservatively during a mean follow-up of 23 +/- 5 months. Eleven of 15 paced (73%) and 31 of 35 (89%) nonpaced patients experienced resolution of their cerebral symptoms (NS). The sensitivity of Holter monitoring in detecting pauses of greater than or equal to 2 seconds in patients with cerebral symptoms was high (76%), but the specificity (32%) and positive predictive values (28%) were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Significance of the clinical presentation in ventricular tachycardia/fibrillation.

We examined the hypothesis that clinical presentation in patients with sustained ventricular tachycardia/fibrillation (VT/VF) predicts clinical, electrophysiologic (EP) findings and long-term outcome. We included in the study 121 consecutive patients seen in our EP laboratory with documented and inducible sustained VT/VF. Patients were categorized into three groups according to their clinical presentation: (1) cardiac arrest (CA)-53 patients; (2) syncope (S)-20 patients; (3) palpitations/dizziness (P)-48 patients. There were no significant differences in age, sex, or prevalence of underlying heart disease between groups. The left ventricular ejection fraction (LVEF) was significantly lower for patients with CA (mean +/- S.D.; 31 +/- 14%) or S (30 +/- 11%) when compared with P (39 +/- 15%) (p less than 0.05). Induction of VT/VF required a more aggressive stimulation protocol (three extrastimuli) in patients with CA (53%) when compared with patients with S (30%) or P (29%) (p less than 0.05). The cycle length of the induced VT was shorter for CA (239 +/- 64 msec) patients as compared with the S (294 +/- 67 msec) or the P (319 +/- 94 msec) patients (p less than 0.01). Polymorphic VT or VF was induced in 28% of CA patients, in 9% of S patients, and in 12% of P patients (p less than 0.05). There were significantly more sudden deaths observed during the 4-year follow-up interval in patients presenting with CA compared to the P group (p less than 0.05). The 4-year survival was 67 +/- 8% for P, 45 +/- 15% for S, and 45 +/- 10% for CA patients (N.S.).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Short-term effect of coronary artery bypass grafting on the signal-averaged electrocardiogram.

Ventricular late potentials at the end of the QRS can be detected on the body surface during sinus rhythm by recording a signal-averaged electrocardiogram (SAECG). In patients with coronary artery disease, these late potentials have been shown to be markers for spontaneous or inducible ventricular tachycardia, or both. The short-term (before and 10 +/- 4 days after coronary revascularization) influence of coronary artery bypass grafting (CABG) on the quantitative SAECG variables was studied in 40 patients with chronic coronary artery disease. Twenty-five of these patients had a previous myocardial infarction. In the 15 patients without previous myocardial infarction, no abnormal SAECG indexes were recorded before CABG and no change in the quantitative SAECG variables was observed after surgery. In the patients with a previous myocardial infarction, 7 (28%) had a late potential before CABG. After CABG, 5 (71%) patients remained late potential-positive, whereas the other 2 (29%) lost their late potential. The mean values of their SAECG variables improved after coronary revascularization. In the entire group of postmyocardial infarction patients, the high-frequency QRS duration had shortened (p less than 0.01) after CABG (the other SAECG indexes did not change). The postoperative arrhythmic complications (transient atrial fibrillation, new onset of ventricular couplets) tended to be more frequent in the postmyocardial infarction group and in patients with late potentials. Our findings suggest that the reported increase in ventricular arrhythmias after CABG is probably not related to a change in the arrhythmogenic substrate for ventricular reentry but is associated with changes in the arrhythmogenic milieu.

Adult↗
PubMed1988

The automatic implantable cardioverter-defibrillator. Clinical experience, complications, and follow-up in 25 patients.

Twenty-five patients with recurrent ventricular tachyarrhythmias underwent implantation of an automatic implantable cardioverter-defibrillator. The mean length of follow-up was 11.9 +/- 10.8 months. Before the implantation, the patients had survived one or more cardiac arrests (mean, 1.7; range, 1 to 4) and episodes of syncope (mean, 2.2; range, 2 to 3) and had received 6.0 +/- 1.0 antiarrhythmic drug trials. The in-hospital complications included death (two patients), reoperation (one patient), intraoperative myocardial infarction (one patient), sensing-failure (one patient), infection (five patients), and pocket seroma (two patients). The posthospital complications included device failure (four patients), device deactivation (one patient), and inappropriate discharge (two patients). The device discharged appropriately in seven patients due to sustained ventricular tachycardia. During electrophysiologic measurements, the energy requirement for successful cardioversion-defibrillation was related to the type of ventricular arrhythmia induced (monomorphic or pleomorphic ventricular tachycardia or fibrillation). Ventricular tachycardia acceleration occurred in ten patients (40%). No significant changes were found in the size of the electrograms or in the cardioversion threshold during early and late follow-up measurements. Life table analysis showed a 12-month survival rate of 86% and an arrhythmic death survival rate of 100%. We confirm the improved rate of survival in this high-risk group of patients, despite significant complications.

Adult↗
PubMed1988

Oral amiodarone loading therapy. I. The effect on serial signal-averaged electrocardiographic recordings and the QTc in patients with ventricular tachyarrhythmias.

The effect of amiodarone loading (1400 mg/day for 7 days) and maintenance therapy (400 mg/day) on the signal-averaged electrocardiogram (SAECG) and the QTc were evaluated in 14 patients. Daily recordings were taken for the first 7 days of loading and on the ninth, twelfth, fourteenth, and twenty-first day of maintenance therapy. All patients had inducible sustained ventricular tachycardia (VT), 10 of them had late potential (LP) positive recording, and four were LP negative during control measurements. Amiodarone loading significantly changed all SAECG indices and prolonged the QTc. Changes induced by amiodarone were present within 24 hours of administration. The time to reach peak effect varied from 6 to 9 days. The maximum increase in late potential duration (LPD) was threefold greater than the increase in filtered QRS duration or QTc (61% vs 18% vs 14%, respectively), suggesting a more pronounced effect on the reentrant pathway than on the remaining myocardium. Of the four LP negative patients, three became LP positive while receiving amiodarone. In conclusion, amiodarone affects all SAECG indices. However, the magnitude of the changes varies, being most pronounced on the LPD. Amiodarone affects the SAECG and the QTc within the first 24 hours. The time of onset of the peak effect varies from 6 to 9 days. LP negative patients with inducible VT frequently became LP positive during amiodarone therapy.

Administration, Oral↗
PubMed1988

Carotid sinus hypersensitivity in patients with unexplained syncope: clinical, electrophysiologic, and long-term follow-up observations.

To assess the incidence and clinical characteristics of carotid sinus hypersensitivity and the relationship to electrophysiologic findings, 76 patients with unexplained syncope underwent carotid sinus massage during electrophysiologic studies for syncope evaluation. Twenty-one patients (28%) were found to have carotid sinus hypersensitivity. Of these 21 patients, 11 (52%) had coronary artery disease, two (10%) had hypertensive heart disease, and eight (38%) had no organic heart disease. During electrophysiologic studies, abnormal sinus node function was found in three patients (14%), abnormal atrioventricular (AV) node function was noted in four (19%), and combined abnormal sinus node and AV node functions were seen in three (14%). Eleven patients (53%) had a normal electrophysiologic study. During carotid sinus massage, sinus arrest alone was observed in 12 patients (57%), and combined sinus arrest and AV nodal block was seen in nine (43%). Thirteen patients were treated with a permanent pacemaker, in whom either carotid sinus massage reproduced the symptom or concomitant sinus node or AV node abnormality, or organic heart disease was present. With a mean follow-up of 42 +/- 19 months, none of these 13 patients had recurrent syncope. However, one of eight patients (13%) who did not receive a pacemaker had recurrence of syncope. Subsequently, this patient has done well after implantation of a pacemaker. These observations suggest that there is a significant incidence of carotid sinus hypersensitivity in patients with unexplained syncope. Permanent pacing appears to be beneficial in selected patients based on clinical and electrophysiologic findings.

Arrhythmia, Sinus↗
PubMed1988

Correlation between the signal-averaged electrocardiogram and electrophysiologic study findings in patients with coronary artery disease and sustained ventricular tachycardia.

Ventricular late potentials at the end of the surface QRS, detected on the signal-averaged electrocardiogram (SAECG) have been shown to be markers for spontaneous and/or inducible ventricular tachycardia (VT) in patients with coronary artery disease (CAD). We examined the correlations between electrophysiologic study (EPS) findings and SAECG indexes in 50 patients with chronic CAD with documented spontaneous VT/ventricular fibrillation (VF), who had either syncope (24 patients) or aborted sudden cardiac death (SCD). The prevalence of late potentials was significantly higher in the syncope patients (75%) compared with the SCD group (46%) (p less than 0.05). No correlation was found between the ventricular refractoriness and the SAECG indexes. There was a significant difference in quantitative SAECG indexes comparing the induction mode of the sustained VT/VF by single and double versus triple extrastimuli; the types of the induced VT (sustained monomorphic, sustained pleomorphic or VF, noninducible); and the cycle length of the induced sustained monomorphic VT with the high frequency QRS duration (QRSD). In conclusion, differences in prevalence and characteristics of ventricular late potentials were found between patients with syncope and with SCD. The degree of abnormality of SAECG indexes correlated with the type and the mode of induction of sustained VT. The magnitude of QRSD of the SAECG correlated with the cycle length of monomorphic VT. The above findings suggest that in patients with CAD and sustained VT/VF the SAECG variables are related to the area of reentry.

Adult↗
PubMed1988

Prognostic significance of signal-averaged ECGs during acute myocardial infarction: a preliminary report.

To gain insight into the prognostic significance of the presence of late potentials detected by body surface signal-averaged electrocardiography during acute myocardial infarction, the authors prospectively studied the relationship between the presence of late potentials and the occurrence of ventricular arrhythmias and sudden death in 52 patients from the initial presentation of myocardial infarction to 14 months after discharge from the hospital. Signal-averaged recordings were performed on admission and again at the time of discharge (mean, 12 days from initial tracing). Late potentials were present on the first recording in 10 patients, 6 of whom had late potentials on the second recording. Twelve patients had late potentials on the second recording, and six of these did not have late potentials on the first recording. Early in-hospital sustained ventricular tachycardia and ventricular fibrillation occurred in three patients, all in the late potential-negative group. There were 10 deaths, 7 in the hospital and 3 late. There was no significant difference in early or late mortality between the late potential-positive and the late potential-negative groups due to the small sample size, although there was a trend toward higher mortality in the late potential positive group. Late potentials detected by body surface signal-averaged electrocardiography did not predict the occurrence of early in-hospital ventricular tachycardia or fibrillation or sudden death. During the acute phase of myocardial infarction, late potentials are often variable and transient findings on signal-averaged electrocardiography.

Arrhythmias, Cardiac↗
PubMed1988

Performance of implantable cardiac rhythm management devices.

Our data represent use, follow-up, and management decisions from eight independently functioning centers and most importantly, actuarial survival of ICRMD's that have been implanted for a sufficient time period to allow assessment of time versus failure. General patterns of possible target durations for adequate performance for present or future generations of similar clinical devices may be suggested by the data that we have presented. However, it would be inappropriate to conclude from these data that any presently implanted ICRMD would have a particular functional reliability. Furthermore, these data only summarized device hardware performance and cannot and must not be used to determine either short-term or long-term individual patient status, management, or outcome.

Electric Countershock↗
PubMed1988

"Quinidine syncope" without lengthening of Q-Tc interval in the presence of left bundle branch block. Role of programmed ventricular stimulation studies.

Idiosyncratic and proarrhythmic reactions to antiarrhythmic drugs are a well-recognized phenomenon and appear to correlate poorly with Q-T prolongation or with the serum concentration of the drug. It therefore becomes difficult to identify patients clinically with an underlying electrophysiologic substrate for ventricular tachycardia which was made manifest by an antiarrhythmic drug, or to determine whether the drug is causing an idiosyncratic reaction (the classic "long Q-T syndrome"). We recently studied a patient with ischemic heart disease and a prolonged corrected Q-T interval (Q-Tc) due to chronic left bundle-branch block. She developed "quinidine syncope," and the Q-Tc was unchanged despite stopping administration of the drug; however, electrophysiologic studies demonstrated reproducibly inducible "torsade de pointes" while the patient was being rechallenged with quinidine, while no inducible arrhythmia was seen during control studies. We conclude that electrophysiologic studies are of clinical value in the clarification of possible drug-induced arrhythmias.

Aged↗
PubMed1988

Familial sudden death. Report of a case and review of the literature.

A 15 1/2-year-old boy died suddenly while swimming. He had a family history of sudden death involving three consecutive generations, including a brother. The patient had a history of exercise-related syncope, for which he was being treated with nadolol. Autopsy showed enlarged heart, normal coronary arteries, right ventricular septal hypertrophy, quadricuspid pulmonary valve, accessory tricuspid valve, and a moderately elongated and thickened mitral valve. Conduction system revealed that the penetrating bundle was pushed to the left side of the summit of the ventricular septum by the right ventricular septal hypertrophy; it was lobulated and showed fatty-fibrous changes. These findings extended throughout the beginning of the bundle branches. We conclude that in this patient with familial sudden death and normal QT interval, the abnormal right ventricular septal hypertrophy altered the course and produced degenerative changes in the conduction system, which may have caused sudden death.

Adolescent↗
PubMed1988

Clinical predictors of electrophysiologic findings in patients with syncope of unknown origin.

Unexplained syncope is a common medical problem. Intracardiac electrophysiologic studies (EPS) have been used to uncover the underlying arrhythmic mechanisms. Electrophysiologic studies are especially helpful in the management of patients with inducible tachyarrhythmias, but is of limited usefulness in those with normal EPS findings. We investigated whether clinical and noninvasive laboratory variables can predict the results of EPS in 89 patients with unexplained syncope. The prevalence of inducible ventricular tachycardia (VT) was 15%; supraventricular tachycardia, 15%; bradyarrhythmias, 41%; and normal EPS, 29%. We used multivariate discriminant function analysis to predict the results of EPS. The variables selected for identification of patients with inducible VT by this analysis include New York Heart Association (NYHA) functional class, gender, digitalis use, nonsustained VT, and atrial fibrillation. Based on our statistical model, performing EPS on 45% of the patients with unexplained syncope would result in a 90% sensitivity in detecting patients with inducible VT. The variables selected for identification of patients with normal EPS findings include: New York Heart Association functional class, heart disease, digitalis use, and intraventricular conduction. Based on this model, it would require that all but 12% of patients with unexplained syncope be studied to achieve a 90% predictive accuracy for identification of patients with normal EPS. During follow-up, recurrence rates for the different EPS categories did not differ significantly. The five-year cumulative survival among the EPS groups were as follows: VT, 37% +/- 28%; SVT, 90% +/- 9%; bradyarrhythmias, 71% +/- 10%; and normal EPS, 96% +/- 4%. Survival of the VT group differed significantly from that of the normal group. In patients with unexplained syncope, EPS findings can be predicted from clinical and noninvasive laboratory data. Mortality during follow-up relates to EPS findings.

Adult↗