PubMed Health⌕ Search

Biomedical subjects

J Kron

Publications and source records attributed to J Kron.

At least 55 records · Page 3Linked to original sources
PubMed1990

Assessment and follow-up of pediatric survivors of sudden cardiac death.

In the young patient resuscitated from sudden cardiac arrest, the risks of recurrence are uncertain and so are the criteria defining therapeutic efficacy for the presumed cause of the initial event. In this study, we analyzed the outcome of 15 consecutive young patients, who were resuscitated from pulseless ventricular tachycardia or ventricular fibrillation and who were evaluated by comprehensive hemodynamic and electrophysiological testing. Patients were 11.2 +/- 2.7 (mean +/- SD) years old at the time of their event, and each was known to have some form of heart disease before sudden cardiac arrest. Ventricular tachycardia or fibrillation was inducible by programmed electrical stimulation in eight patients. Accessory atrioventricular connections, with antegrade effective refractory periods less than 220 msec, were identified in three patients. Sustained atrial flutter was the only arrhythmia inducible in two patients, and no arrhythmias were inducible in two other patients. Surgical or electrophysiological-guided medical therapy resulted in noninducibility of the ventricular arrhythmias in six patients. Surgical division of the accessory atrioventricular connections was performed in three patients, and arrhythmias were not inducible after operation. The four patients with atrial flutter or without defined arrhythmia were treated with an empiric therapy. During 37 +/- 14 months of follow-up, the nine patients with documented noninducibility of a defined cause of sudden cardiac arrest were free of recurrent events. In contrast, during 18 +/- 10 months of follow-up, two of the six patients with empiric therapy or persistent inducibility of ventricular tachycardia died suddenly, and three others had recurrence of ventricular tachycardia or fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Current management of the Wolff-Parkinson-White syndrome.

The Wolff-Parkinson-White syndrome is a multifaceted disorder that ranges from asymptomatic to life threatening. Accounting for approximately 20% of cases of paroxysmal supraventricular tachycardia and with a prevalence perhaps as high as 1 per 500, it is far from a rare disorder. Considering the potentially lethal complications following the administration of digoxin or verapamil, all physicians treating arrhythmias should know when to suspect the Wolff-Parkinson-White syndrome. A careful review of electrocardiograms helps identify cases of the disorder despite a wide range of findings that may mimic other conditions. Major advances in the efficacy of surgical procedures to cure this syndrome make this a reasonable alternative to life-long medical therapy for many patients. Unfortunately, available diagnostic tests lack the positive predictive value to reliably distinguish patients at risk of sudden death. This review is an update for general internists of the major developments in the evaluation and treatment of the disorder and provides specific examples helpful in differentiating these patients.

Electrocardiography↗
PubMed1990

Misdiagnosing ventricular tachycardia in patients with underlying conduction disease and similar sinus and tachycardia morphologies.

Six patients presented with wide-complex tachycardias with QRS morphologies similar to those seen on their electrocardiograms that showed normal sinus rhythms. During normal sinus rhythm, each patient had an underlying intraventricular conduction abnormality or bundle branch block. Despite the similarity of the QRS complexes to those seen during sinus rhythm, the tachycardias subsequently proved to be ventricular in origin in each patient. It is important not to misdiagnose these disorders as supraventricular tachycardia as an erroneous diagnosis may result in inappropriate management.

Aged↗
PubMed1989

Psychophysiological factors in ventricular arrhythmias and sudden cardiac death.

Plasma catecholamine levels were measured preceding programmed electrophysiological studies of patients who had survived a ventricular tachyarrhythmia episode. Psychological assessments of desire for control, locus of control and behavior pattern were obtained. Psychophysiological variables were analysed with respect to the severity of arrhythmias induced by the electrophysiological procedure. Analysis of data from 17 subjects showed desire for control was significantly higher in those with induced sustained arrhythmias than in those in which nonsustained arrhythmias were induced. No relationship was found between behavior pattern and arrhythmia severity or plasma catecholamine levels. There was a significant interaction between desire for control and behavior pattern with respect to epinephrine level. The findings indicate that psychological factors such as desire for control may be associated with potentially lethal arrhythmias and implicated in sudden cardiac death.

Adult↗
PubMed1988

Limited value of programmed electrical stimulation from multiple right ventricular pacing sites in clinically sustained ventricular fibrillation or ventricular tachycardia associated with coronary artery disease.

One-hundred and fifty patients with coronary artery disease and a documented history of sustained ventricular tachyarrhythmias were studied to determine if programmed electrical stimulation (PES) from a second right ventricular (RV) pacing site optimizes the induction of such sustained arrhythmias. The first PES test was performed from 2 RV pacing sites (apex and outflow tract or septum) using the apex first in each patient. All patients underwent a second PES within 6 to 24 hours of the first; both studies used up to 4 ventricular extrastimuli, in the absence of antiarrhythmic treatment. The second PES was performed from a single RV apical site using a pacing catheter retained from the first study. During the first day's study, 74 patients (49%) had sustained ventricular tachycardia induced from the RV apex. Only 11 of the remaining 76 patients (7% of the total group) were inducible exclusively from a second RV pacing location during the first day's testing. Seven of these 11 patients, as well as 15 additional patients who did not have ventricular tachycardia induced from either site on the first day's study, were inducible from the RV apex during the second drug-free study. Among patients with sustained ventricular tachyarrhythmias, limiting PES to a single RV site, with the option of performing a second study in those who are initially noninducible is more effective in inducing sustained ventricular tachyarrhythmias than is PES performed from 2 RV pacing sites.

Adult↗
PubMed1988

Long-segment coronary ulcerations in survivors of sudden cardiac death.

Angiographically irregular coronary stenoses usually represent plaque rupture with or without superimposed thrombi. Long-segment coronary stenoses with diffuse irregularities (type IIB morphology) have been shown to be more prevalent than focal irregular lesions (type IIA morphology) in survivors of cardiac arrest without acute myocardial infarction. To further understand the pathogenetic importance of type IIB morphology, the clinical and angiographic characteristics in 59 such patients were analyzed. Type IIB lesions accounted for 63% of all type II lesions. Type IIB patients were older than type IIA patients (p less than 0.05). There was a tendency for type IIB morphology to be associated with more extensive disease than other types of lesion morphology (p less than 0.10). Type IIB morphology probably reflects more advanced atherosclerosis. Platelet microemboli may precipitate spasm and/or acute ischemic ventricular tachyarrhythmias. It is possible that long-segment coronary ulcerations are associated with a higher risk for local coronary thromboembolism, and hence with sudden death, than focal lesions.

Aged↗
PubMed1988

Angiographic coronary morphology in survivors of cardiac arrest.

Autopsy studies in victims of sudden coronary death revealed intramyocardial platelet aggregates with microscopic myonecrosis downstream from ruptured atherosclerotic plaques. Ruptured plaques usually manifest angiographically as irregularly bordered (type II) lesions. To investigate the possible pathogenic role of ruptured plaques in arrhythmic death, we analyzed clinical, angiographic, and electrophysiologic data from 49 survivors of cardiac arrest without acute myocardial infarction. All patients had greater than or equal to 50% stenoses of greater than or equal to one coronary artery; 16 had type II morphology, and 33 did not. Type II morphology was more prevalent in patients without inducible sustained monomorphic ventricular tachycardia (11 of 22 or 50%) than in those with it (five of 27 or 19%), p less than 0.05, and patients without akinetic or dyskinetic segments (eight of 14 or 57%) than in those with them (eight of 34 or 24%), p less than 0.06. Thus type II morphology is more prevalent in patients without a demonstrable anatomic and/or electrophysiologic substrate for reentrant ventricular tachycardia, indirectly implicating ruptured plaques in the pathogenesis of cardiac arrest in this subset of patients.

Aged↗
PubMed1988

Idiopathic dilated cardiomyopathy. Role of programmed electrical stimulation and Holter monitoring in predicting those at risk of sudden death.

The prognostic role of programmed electrical stimulation and Holter monitoring was evaluated in 21 patients with idiopathic dilated cardiomyopathy who had no prior history of ventricular tachyarrhythmias. During a mean follow-up period of 23 months, sudden death or ventricular fibrillation occurred in four (20 percent). One patient died of complications of sepsis, and one underwent cardiac transplantation. Programmed electrical stimulation (PES) resulted in five or more beats of induced ventricular tachycardia in seven patients (33 percent), but was a poor predictor of sudden death (sensitivity = 20 percent). Thirteen patients (62 percent) had complex ventricular ectopy (Lown class 4A or 4B) by ambulatory monitoring. This was a sensitive (80 percent) but not specific (31 percent) marker for sudden death. The predictive value of a negative Holter monitor study was high (80 percent) for identifying those at low risk of sudden death. The results of this prospective study suggest that programmed ventricular stimulation and routine ambulatory monitoring are poor predictors of sudden death in this population.

Adult↗
PubMed1987

Ventricular fibrillation survivors in whom tachyarrhythmia cannot be induced: outcome related to selected therapy.

Eight-five patients were studied to determine the prognosis of the ventricular tachyarrhythmias at the time of electrophysiologic study. Twenty-five patients (29%) were not inducible when we used a stimulation protocol consisting of up to four extrastimuli delivered at two right ventricular sites. Patients with no inducible arrhythmias were younger (53 vs 59 yrs; p = .06) and had higher ejection fractions (.49 vs .34; p less than .04) than the inducible ventricular fibrillation survivors. Sex, cardiac diagnosis, time from event to electrophysiologic study, and antiarrhythmic therapy at the time of event did not discriminate between those with and those without inducible ventricular tachyarrhythmias. Survival free of recurrent sudden death or ventricular tachycardia was .86 +/- .05 and .95 +/- .05 for patients with and without inducible tachyarrhythmias, respectively (p = .22). Nine of 25 (36%) patients with no inducible arrhythmias developed inducible ventricular tachyarrhythmias when testing was repeated with an antiarrhythmic drug. Ventricular fibrillation survivors not inducible at the time of programmed ventricular stimulation (using a stimulation protocol consisting of four extrastimuli delivered at two right ventricular sites) seem to have a good prognosis. Many "noninducible" patients develop inducible tachyarrhythmias when placed on antiarrhythmic therapy. Because it is possible that these drugs are proarrhythmic, empiric antiarrhythmic therapy should be avoided in these patients.

Adult↗
PubMed1987

Determinants of induced sustained arrhythmias in survivors of out-of-hospital ventricular fibrillation.

We prospectively studied 196 consecutive survivors of out-of-hospital ventricular fibrillation (VF) not associated with acute myocardial infarction and 46 consecutive, control patients without prior ventricular arrhythmias. Programmed stimulation included two extrastimuli (S3 protocol) in all patients and three extrastimuli (S4 protocol) in the last 140 study patients and in all control patients. Sustained ventricular tachycardia (VT) or VF was not induced in any control patient. In study patients, logistic regression identified two independent predictors of induced, sustained VT for both S3 and S4 protocols: prior spontaneous, sustained VT (37 patients; p less than or equal to .001) and prior myocardial infarction (113 patients; p = .005). With the S3 protocol, sustained VT was induced in 54% of patients with both prior myocardial infarction and prior sustained VT vs 4% without either; with the S4 protocol, sustained VT was induced in 91% vs 13%, respectively. Eighty-three percent of induced VT episodes had a cycle length less than 300 msec, and all required termination by cardioversion or pacing. VF was induced only in survivors of out-of-hospital VF without prior, spontaneous, sustained VT (S3 protocol, 9%; S4 protocol, 24%) but not in study patients with prior sustained VT (S3, p = .10; S4, p = .05) or control patients (S3, p = .06; S4, p = .01). The mean coupling intervals of extrastimuli that induced VF were not significantly different from the intervals that induced sustained VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1986

Prognostic value of programmed electrical stimulation in patients with a recent episode of unstable angina.

Patients with a recent episode of unstable angina have a 10% 1-year risk of sudden cardiac death. To determine prospectively whether electrophysiologic testing might be useful in predicting sudden death, 20 patients admitted to our hospital underwent programmed electrical stimulation as part of their evaluation. None had persistent angina, severe congestive heart failure, or sustained arrhythmias at the time of testing. Because of their long-term benefits, beta-blocking agents were continued whenever possible (18 of 20 patients). Ten of 20 patients (50%) had inducible ventricular tachycardia. In 19.5 months' mean follow-up, three patients (15%) either died suddenly or survived an episode of ventricular fibrillation. Programmed electrical stimulation was an insensitive (33%) and nonspecific (47%) predictor of sudden death in these patients. Programmed ventricular stimulation soon after admission for unstable angina is not a useful prognostic indicator for sudden death. Such patients do have a frequent induction of ventricular arrhythmias which appears to be a nonspecific marker of underlying coronary disease.

Actuarial Analysis↗
PubMed1986

Reproducibility of arrhythmia induction with intracardiac electrophysiologic testing: patients with clinical sustained ventricular tachyarrhythmias.

In order to characterize the day to day reproducibility of arrhythmias provoked during electrophysiologic stimulation, 114 patients with documented sustained clinical ventricular tachyarrhythmias were studied. Two baseline electrophysiologic tests were performed in the drug-free state and within 6 to 24 hours of one another. There was a significant increment (p less than or equal to 0.02) in the induction of sustained ventricular tachyarrhythmias as the number of programmed extrastimuli increased from one (10% induction) to four (64% induction). Provoked arrhythmias were observed to be more frequently nonreproducible (as reflected in a major change in rate or duration, or both, of an induced ventricular arrhythmia between baseline tests) as the number of extrastimuli increased from one (7%) to four (27%). Nonreproducibility with three and four extrastimuli was not significantly greater than when two extrastimuli were utilized. Electrophysiology-directed drug trials should be interpreted in light of this observed variability in induced arrhythmias.

Adolescent↗
PubMed1986

Granulomatous myocarditis. Diagnosis by endomyocardial biopsy and response to corticosteroids in two patients.

Granulomatous involvement of the myocardium is of uncertain etiology, rarely diagnosed premorbidly, and the response to therapy is unknown. We report two patients with granulomatous disease apparently isolated to the myocardium, one presenting with cardiac arrest secondary to ventricular tachycardia, one with heart block. In both cases, the clinical rhythm was substantiated by electrophysiologic studies and neither case had evidence of significant myocardial dysfunction. In both, treatment was instituted with orally administered prednisone. One patient died suddenly two months following onset of therapy. Limited autopsy demonstrated no evidence of granulomatous involvement of the myocardium. The other patient is alive without clinical arrhythmias on amiodarone therapy; however, inducible ventricular tachycardia persists. Repeat endomyocardial biopsy in this patient demonstrated no granulomatous disease. These cases are discussed and the literature reviewed.

Adult↗
PubMed1986

Sudden death prediction by programmed electrical stimulation following myocardial infarction.

To determine prospectively whether electrophysiologic testing is prognostically useful following a myocardial infarction, 38 patients were studied. Ventricular tachycardia was induced in 32 of 38 (84%) patients (sustained in 12) and was significantly increased with the use of three or four extrastimuli. In 17 months' mean follow-up, 4 patients died suddenly or survived an episode of sustained ventricular tachycardia. Programmed ventricular stimulation was a sensitive but not a specific predictor of these events with an overall 24% predictive accuracy. The use of one or two extrastimuli substantially improved specificity but was insensitive in predicting sudden death or ventricular tachycardia. Programmed ventricular stimulation soon after uncomplicated myocardial infarction was not a useful prognostic indicator for sudden death or subsequent ventricular tachycardia.

Adult↗
PubMed1985

[Effect of age, basic disease and treatment of kidney patients in the stage of compensated retention on prognosis in a chronic hemodialysis program].

In an examination of 82 patients with chronic haemodialysis the quality of the care at the stage of the compensating retention proved to be the most important factor determining the prognosis. The 6-year survival rate of patients undergoing for a long time dialysis in a dispensary of a renal centre was 82%, the number of those patients who were transferred to dialysis at the terminal stage of renal insufficiency was, however, only 28%. Particularly in patients older than 45 years the care in the preliminary state of the dialytic treatment increasingly gains importance. As cause for the favourable prognosis of patients with polycystic degeneration of the kidneys its better care at the stage of compensated retention is discussed. When the increase of the creatinine level is more than 350 mumol/l patients with renal insufficiency should be transferred to the dispensaire of a renal centre.

Adolescent↗