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Biomedical subjects

M B Rosenbaum

Publications and source records attributed to M B Rosenbaum.

At least 37 records · Page 2Linked to original sources
PubMed1984

Efficacy of amiodarone during long-term treatment of malignant ventricular arrhythmias in patients with chronic chagasic myocarditis.

Oral amiodarone was administered to 24 patients with chronic chagasic myocarditis (CCM) and malignant ventricular arrhythmias. Control 24-hour Holter recordings revealed frequent ventricular premature beats (VPBs) (157 to 2572/hr; mean 714 +/- 125), multiform VPBs, and countless numbers of ventricular couplets in all patients, R-on-T phenomenon in 17 patients, and ventricular tachycardia in 21 patients. Amiodarone caused total and persistent suppression of ventricular couplets and tachycardia and greater than 93% reduction of VPB number in 22 patients, during a follow-up of 26.6 months (range 2 to 55 months). In 1 patient, ventricular couplets and tachycardia persisted despite the fact that a 98.2% reduction of VPB number was achieved. This latter patient was the only one in the whole group who experienced sudden death. The maximal antiarrhythmic effect was attained gradually after 3 to 26 weeks (mean 7.4). In four patients in whom treatment was discontinued after 3 to 12 months, the antiarrhythmic protection lasted 4 to 9 weeks. In nine patients the dose of amiodarone was 600 to 800 mg/day. In 15 patients the dose had to be increased to 800 to 1000 mg/day. Despite the presence of congestive heart failure in seven patients and intraventricular block in 17 patients, no limiting side effects were observed. Amiodarone proved to be extremely effective and safe against the most malignant ventricular arrhythmias of CCM.

Adult↗
PubMed1983

Ten years of experience with amiodarone.

Arrhythmias may be controlled in most patients with recurrent supraventricular tachycardia or atrial fibrillation with small to moderate maintenance doses of amiodarone (100 to 400 mg/day). Moderate doses (400 mg/day) are also highly effective in suppressing "warning" ventricular arrhythmias in patients with chronic ischemic heart disease, particularly if the goal of treatment is to eliminate ventricular couplets, runs of ventricular tachycardia (VT), and the "R on T" phenomenon. Treatment and prevention of sustained recurrent VT and the malignant arrhythmias of chagasic myocarditis require, however, doses of about 800 mg/day, which may be higher than those needed for ischemic heart disease complicated by VT and ventricular fibrillation. Clinical studies suggest an elimination half-life for amiodarone of about 30 days (range 15 to 100 days). Thus there is a pretherapeutic latency period that varies according to the type of arrhythmia and the doses employed. The maximal effects (as well as the most significant adverse effects) are not attained before 90 to 150 days of treatment, and the antiarrhythmic protection may persist for varying intervals, up to 150 days or more, after the drug has been discontinued. Side effects are not negligible but are generally dose dependent. Despite these side effects, many patients have been treated by us with amiodarone for as long as 5 to 8 years--and for up to 10 years in some cases. Amiodarone appears to be one of the most promising drugs for the possible prevention of ventricular fibrillation and sudden death.

Amiodarone↗
PubMed1983

Supernormal excitability and conduction.

The authors examine circumstances in which supernormality causes specific electrocardiographic events. True supernormal conduction is much more common than previously thought. A complete scanning of the cardiac cycle in patients with phase 3 BBB or with second-degree or advanced infranodal AV block would reveal that a much larger number of cases of supernormal conduction would be uncovered.

Arrhythmias, Cardiac↗
PubMed1982

Efficacy of chronic amiodarone therapy in patients with variant angina pectoris and inhibition of ergonovine coronary constriction.

In three patients with vasospastic angina pectoris, chronic amiodarone administered orally at doses of 800 and 1,000 mg/day totally suppressed spontaneous episodes of ischemic chest pain for 8 to 14 months. Before treatment, ergonovine maleate 0.2 to 0.4 mg intravenously provoked chest pain and similar ischemic ECG changes as those occurring spontaneously. During amiodarone treatment ergonovine vasoconstriction was totally or partially inhibited. In addition to calcium-blocking agents, amiodarone is another spasmolytic drug which effects smooth muscle relaxation by different mechanisms and appears to be useful for the chronic treatment and prevention of variant angina. The vasodilator property of amiodarone is achieved by both direct action and noncompetitive alpha receptor antagonism of coronary vasculature.

Administration, Oral↗
PubMed1982

Electrotonic modulation of the T wave and cardiac memory.

Alterations in the sequence of ventricular activation (left bundle branch block occurring spontaneously or induced by atrial pacing; right ventricular pacing) were studied and shown to induce two opposite changes in the order of ventricular repolarization. One, which causes classic secondary T wave changes, occurs and disappears instantaneously, and is proportional in magnitude to the QRS complex but of opposite direction. The other, which requires a long time to reach its maximal effect and to be dissipated, shows the same direction as the abnormal QRS forces but becomes apparent only when normal activation is restored. The former is a well known consequence of prolongation of the activation time, but the latter appears to be modulated by electrotonic interactions occurring during cardiac activation, in such a way that repolarization is delayed in sites where depolarization begins, and accelerated in sites where depolarization terminates. Our study suggests that electrotonically modulated T wave changes show accumulation and memory, and may persist for days or weeks after the provoking stimulus (the change in the activation sequence) is discontinued. The fact that any shift of the activation sequence may produce "pseudoprimary" T wave changes that may persist long after cessation of the triggering factor has wide clinical implications. Electrotonic modulation of ventricular repolarization is a basic electrophysiologic mechanism that may account for several features of normal and abnormal T waves, and for the possible existence of a heart memory.

Bundle-Branch Block↗
PubMed1982

Electrocardiographic changes evoked by ajmaline in chronic Chagas' disease with manifest myocarditis.

Conversion from Chagas' infection to chagasic myocarditis occurs slowly and the earliest signs of myocardial involvement are hard to define. To obtain new information on this difficult clinical problem, ajmaline was administered (1 mg/kg body weight intravenously) to 101 patients with Chagas' infection and to 46 patients without such infection (control group). In 3 patients in the control group left anterior hemiblock alone occurred whereas in the group with Chagas' infection, ajmaline caused the occurrence of right bundle branch block, left anterior hemiblock, or both, in 32 patients (31.6 percent), ventricular extrasystoles in 8 (7.9 percent) and ischemic ST-T changes in 7 (6.9 percent). Ajmaline may thus evoke the most typical electrocardiographic changes of chronic chagasic myocarditis in patients without signs of myocardial involvement or only minor nonspecific signs. A positive ajmaline test, defined in the present context as the occurrence of a fascicular block, ventricular arrhythmias or ischemic ST-T changes, may indicate the existence of localized areas of injured myocardial tissue, not enough to alter the electrocardiogram by itself, but able to give rise to severe abnormalities after exposure to the drug. The test may therefore be used as a nonspecific detector of myocardial damage, and thus may have a much broader scope of clinical application. In chronic Chagas' infection, the ajmaline test is a relatively simple and apparently safe procedure that may serve to unveil the earliest signs of chagasic myocarditis.

Adolescent↗
PubMed1982

Usefulness of the ajmaline test in patients with latent bundle branch block.

Twelve patients were studied with intermittent bundle branch block whose conduction disturbance disappeared completely and could no longer be recorded even after provoked changes in heart rate. Premature atrial stimulation and atrial pacing at rapid rates were performed in nine patients; in none of these nine were these procedures able to evoke the complete bundle branch block pattern that all patients exhibited before the spontaneous normalization of conduction. In marked contrast, the administration of ajmaline (1 mg/kg body weight, intravenously in 90 seconds) caused the bundle branch block pattern to reappear in 10 (83.3 percent) of the 12 patients 30 to 120 seconds after the end of the injection, and in 11 patients (91.6 percent) when additional atrial stimulation was performed in 1 of the 2 "failures." This pharmacologic test was much more rapid and simple than electrophysiologic testing and it was noninvasive. Results of this study suggest that some form of subclinical fascicular injury was present (or had persisted) at a time when intraventricular conduction was persistently normal even though no significant physiologic alteration could be demonstrated by the atrial stimulation techniques. The ajmaline test may become a valuable tool for uncovering cases of latent bundle branch block and furthering our knowledge of the early natural history of intraventricular block.

Adult↗
PubMed1982

The hyperventilation test as a method for developing successful therapy in Prinzmetal's angina.

In 10 cases of Prinzmetal's angina in which episodes of myocardial ischemia were easily and reproducibly induced by hyperventilation, this test was performed 111 times, 41 times under control conditions and 70 times during treatment with one or more of the following drugs: phentolamine, isosorbide dinitrate, propranolol, verapamil, nifedipine and amiodarone. Seventeen of 18 negative tests performed under the influence of a long-acting drug coincided with total remission of the patient's anginal episodes when this drug was administered on a short- or long-term basis. No patient died or sustained infarction during a follow-up period of 10.9 months. A negative test was thus a good indication that the clinical response to the corresponding drug would be favorable. The electrocardiographic changes and chest pain provoked by hyperventilation occurred not when alkalosis was greatest (hydrogen ion [pH] change from 7.42 to 7.58, p less than 0.001), but when pH was approaching normal or control values. The onset of electrocardiographic changes occurred an average of 175 seconds after the end of hyperventilation and, in two cases, the time lag was as much as 480 and 705 seconds, respectively. This raises several questions regarding the true mechanism triggering coronary spasm under such conditions. The hyperventilation test appears to be a useful and safe procedure for selecting the best possible drug for long-term treatment of Prinzmetal's angina as well as for comparing the relative efficacy of different drugs.

Adult↗
PubMed1982

Psychiatric aspects of replantation surgery.

The surgical literature on replant patients was reviewed and reports of psychiatric complications were noted. Data for this study were obtained from semistructured psychiatric interviews administered to 30 replant patients within a few days of admission. In addition, 24 of the patients received two or more follow-up interviews. Thirty-three percent of the patients showed evidence of preaccident psychopathology; 20% suffered from a substance use disorder. Fifty percent of the patients reported a stressful life event within the year antedating the accident. Sixty percent of the patients were assessed as warranting psychiatric intervention. The presence of preaccident psychopathology, family or marital dysfunction, previous psychiatric history, and a stressful life event were all positively associated with the occurrence of an adverse postoperative emotional reaction. Case material is presented to illustrate specific psychological issues of replantation surgery, such as those concerning body image and the disruption to body integrity. Suggestions for further research are given.

Accident Proneness↗
PubMed1982

Malignant ventricular arrhythmias in chronic chagasic myocarditis.

We studied 28 cases of chronic chagasic myocarditis (CCM) with frequent ventricular arrhythmias. Two-hundred and three conventional ECGs recorded during 3 months showed ventricular extrasystoles (VE) ranging between 0.2 and 6 per ten beats in 100%; multiform VE in 97.04%; couplets in 79.31%; ventricular tachycardia (VT) in 42.85%; and R on T in 21.67%. A 24-hour continuous recording showed that VE ranged between 3780 and 61733 (mean 16618 +/- 2627); multiform VE and couplets were present in 100% of patients, and VT was present in 78.5%. In 16 patients (group I) the frequency of VE was persistently high, without diurnal variation; 11 patients showed sustained reduction during sleeping hours and only one showed an increase during night sleep (group II). Even in group II, VE never disappeared for periods longer than 10 minutes. In five patients, four 24-hour recordings were obtained at weekly intervals, and in five other patients a second 24-hour recording was performed 10 to 24 months later. The remarkable frequency, persistence and low variability of ventricular arrhythmias in CCM suggest that such arrhythmias can be used as a most stable, reliable, but highly demanding model for testing the efficacy of antiarrhythmic drugs.

Adult↗
PubMed1982

Ventricular fibrillation after intravenous atropine in a patient with atrioventricular block.

A 69-year-old black woman with complete AV block developed ventricular fibrillation following an IV injection of 1 mg of atropine sulphate. After a successful DC countershock, the ECG showed a polymorphous ventricular tachycardia which subsided spontaneously. Cardiac catheterization revealed a small left ventricular diverticulum and normal coronary arteries. This seems to be the first reported case of atropine-induced ventricular fibrillation in a patient with complete AV block. The fact that this occurred without previous change of the ventricular rate suggests that the adverse action of atropine was mediated through a mere vagolytic effect at the ventricular level.

Aged↗
PubMed1982

Abnormal Q waves in right sided chest leads provoked by onset of right bundle-branch block in patients with anteroseptal infarction.

In five cases of anteroseptal myocardial infarction complicated by intermittent right bundle-branch block, the onset of right bundle-branch block provoked the appearance of abnormal Q waves in leads V1 and V2, whereas a small initial R wave was present in the same leads during normal conduction. The intermittency of the conduction disturbance indicated that the Q waves were "right bundle-branch block dependent". It was also apparent that right bundle-branch block shifted the electrical location of the infarct towards the right, and made it look much larger. Right bundle-branch block dependent Q waves may arise during the acute stage of an anterior infarct suggesting, fallaciously, that an acute extension has occurred, or during the chronic stage, leading to the erroneous supposition that a new infarct had developed. The abnormal Q waves anteroseptal infarction complicated by fixed right bundle-branch block, though obviously related to the infarct, may be dependent on the right bundle-branch block.

Adult↗
PubMed1982

Modulation of parasystolic activity by nonparasystolic beats.

We studied 12 patients with ventricular parasystole in whom pacemaker activity could be modulated by nonparasystolic beats (NPBs). In six patients (group 1) in whom the intrinsic parasystolic cycle length (XX interval) was obtained without interposed NPBs, we found that NPBs falling during the first half of the cycle prolonged the XRX interval (containing one NPB) and that NPBs falling during the second half of the cycle abbreviated the XRX interval; both effects were maximal when NPBs fell close to the middle of the cycle and were separated by a reversal point. However, because of mutual interference between parasystolic beats and NPBs, only 13.2-43.4% of the parasystolic cycle could be effectively scanned. We also found that the XRX and RX intervals were linearly related. This relationship served to establish that in six patients in whom the XX interval was not obtained (group 2), modulation showed a similar behavior, although neither the reversal point nor the sense of the modulation could be determined. In this report, we suggest diagnostic criteria of parasystolic modulation.

Arrhythmias, Cardiac↗
PubMed1981

Spontaneous remission in variant angina.

Four cases of variant angina are reported, in which total remission of anginal pain was documented during a follow-up of seven months, four years, five years, and 15 years, respectively. During this relatively long follow-up, the clinical course of the disease was apparently benign. The possibility of spontaneously and complete recovery may be postulated. The natural history of relatively benign forms a variant angina is poorly known and understood.

Adult↗
PubMed1981

Concealed ventricular parasystole uncovered in the form of ventricular escapes of variable coupling.

Exit block from a parasystolic focus is recognized when automatic discharges fail to become manifest during the excitable phase of the ventricular cycle. In the present study, an apparently complete exit block and a persistently concealed ventricular parasystole (VP) resulted from an exit refractory period (ExRP) longer than the sinus cycle length. Slowing of the heart rate caused the concealed VP to become apparent in the form of ventricular escapes of variable coupling and as an idioventricular rhythm that failed to show initial "warming up." These features reflect the fact that the automatic focus is protected from activity of the sinus impulses, which, however, can induce a prolonged ExRP. Seven cases of concealed VP are discussed. In two, concealment occurred spontaneously during the follow-up of a typical VP; in three, it was provoked by conduction-depressing drugs; and in two, ventricular escapes of varying coupling were shown to represent the manifestation of a concealed and previously unrecognized VP. In two cases, isoproterenol caused reappearance of typical VP, probably through a shortening of the ExRP. While isoproterenol may be useful for uncovering a concealed VP, conduction-depressing drugs may be used to provoke or increase exit block. Total extinction of the VP seemed to occur in two patients during follow-up studies.

Aged↗
PubMed1981

Long-term management of sustained, recurrent, symptomatic ventricular tachycardia with amiodarone.

Twenty-three patients with sustained, recurrent, symptomatic ventricular tachycardia were treated with oral amiodarone. Initial doses were 600-2000 mg/day and maintenance doses were 200-1200 mg/day. Amiodarone was highly effective in 20 patients (87%), seven of whom had a follow-up of 30 months or longer, including two who were followed for 5 years. Three patients died within the first 45 days, three died suddenly after a follow-up of 33.5 months, and four had a nonarrhythmic death after a follow-up of 25 months. Fifteen patients (65%) had no recurrence during a follow-up of 21.5 months, while five (22%) had isolated recurrences during a follow-up of 32.2 months. The average maintenance dose was 713 mg/day in the 15 patients who did not have recurrences and 375 mg/day in the five patients who had recurrences (p less than 0.001). Both short- and long-term tolerance were excellent and there was not a single case in which treatment had to be discontinued. The main disadvantage of amiodarone was that it took an average of 9.5 days to reach anti-arrhythmic efficacy. The main advantages were prolonged duration of action (recurrences occurred only 15-60 days after the drug was discontinued or the dose lowered, virtual absence of contraindications, doses as high as 2000 mg/day were safe and patient compliance was excellent.

Adult↗