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Biomedical subjects

S Zaim

Publications and source records attributed to S Zaim.

28 records · Page 2Linked to original sources
PubMed1996

Characterization of spontaneous recurrent ventricular arrhythmias detected by electrogram-storing defibrillators in sudden cardiac death survivors with no inducible ventricular arrhythmias at baseline electrophysiologic testing.

This retrospective study characterized the recurring ventricular arrhythmias with an electrogram-storing defibrillator in survivors of sudden cardiac death who had no inducible sustained ventricular arrhythmias at baseline electrophysiologic testing (EPS). The study group was composed of 24 selected patients with documented ventricular fibrillation (VF) without need of revascularization or chronic antiarrhythmic therapy. The EPS protocol usually consisted of three extrastimuli at two drive cycles at two right ventricular sites. Nonischemic cardiomyopathy was the most frequent structural abnormality (n = 11) followed by coronary artery disease (n = 7). The mean ejection fraction was 0.37 +/- 0.13. Cardiac status did not appear to change during a mean follow-up period of 16.4 +/- 12.5 months, and eight (33%) patients received appropriate shocks in that time period. On the basis of intracardiac electrograms, 7 (88%) patients experienced VF and 1 (12%) patient had ventricular tachycardia as the first recurring arrhythmia. Four patients had additional recurrences and all were VF episodes. VF was usually present from the onset of the arrhythmia. In addition, 9 (38%) patients had nonsustained ventricular arrhythmias that were solely VF in 6 (67%). In conclusion, VF of sudden onset was the most frequent recurring sustained ventricular arrhythmia in this group.

Aged↗
PubMed1994

Perioperative complications of cardioverter-defibrillator implantation: the Emory experience.

Over a 5-year period, 110 cardioverter-defibrillators (109 epicardial, 1 transvenous) were implanted consecutively in selected patients with ventricular tachyarrhythmias. The perioperative course of this patient population was examined to determine the associated morbidity and mortality of the procedure. Patients were predominantly male, with coronary artery disease and a decreased left ventricular ejection fraction. Most underwent median sternotomy for implantable cardioverter defibrillator implantation. The incidence of perioperative mortality was found to be 2.7%. New-onset atrial fibrillation or flutter occurred in 17.3% of the patients during the postoperative period and aggravation of ventricular tachyarrhythmias in 19.1%. The ICD system became infected in 2.7% of the patients and the mediastinal incision site infected in 2.4%. Pneumonia developed in 4.5%. Other complications included significant blood loss, ICD pocket hematomas, and lead dislodgement. There is an appreciable incidence of morbidity and mortality associated with ICD implantation.

Adult↗
PubMed1994

Liver metastases: safety and efficacy of detection with superparamagnetic iron oxide in MR imaging.

PURPOSE: To evaluate the clinical and biologic safety of superparamagnetic iron oxide (SPIO) as a contrast agent in magnetic resonance (MR) imaging and to assess its efficacy in the detection of liver metastases. MATERIALS AND METHODS: Twenty adults with liver metastases underwent MR imaging at 1.5 T before and 1 hour after infusion of SPIO. Four spin-echo (SE) sequences and one gradient-echo (GRE) sequence were used. RESULTS: There were no adverse reactions. Alterations in serum protein, serum iron, transferrin, and ferritin levels and transferrin saturation coefficient were statistically significant. The mean tumor-to-liver contrast-to-noise ratio (C/N) increased markedly with all sequences. The best postcontrast tumor-to-liver contrast was obtained with the GRE sequence (repetition time msec/echo time msec = 300/15). The mean number of apparent lesions detected after administration of SPIO increased by 12 with the proton-density-weighted SE sequences (800/30 and 2,500/30), four with the T2-weighted SE sequence (2,500/90), and seven with the GRE sequence (300/15). CONCLUSION: SPIO is safe, increases tumor-to-liver C/Ns with some sequences, and improves the detection of liver metastases.

Contrast Media↗
PubMed1993

Efficacy of a tiered therapy defibrillator system used to treat recurrent ventricular arrhythmias refractory to drugs.

OBJECTIVE: To evaluate an implantable tiered therapy defibrillator system that delivered antitachycardia pacing treatment for slower well tolerated ventricular tachycardias and cardioversion or defibrillation for fast tachycardias or ventricular fibrillation. METHODS: A tiered treatment device (Ventritex Cadence V-100) was implanted in 30 patients with ventricular tachycardia that was refractory to drugs. Efficacy was evaluated by the responses of induced or spontaneous arrhythmias to the treatments delivered. RESULTS: Antitachycardia pacing successfully terminated 80% of episodes of ventricular tachycardia induced by non-invasive programmed stimulation, but acceleration was brought about by pacing in six patients in 10% of episodes. During a follow up of two to 17 (mean seven) months, 18 patients (60%) had recurrence of ventricular arrhythmias. Antitachycardia pacing terminated ventricular tachycardia in 17 of 18 patients in 87% of episodes. Twelve patients received shocks for ventricular tachycardia or fibrillation. Failure of pacing, with subsequent cardioversion, occurred in nine patients (50%) in one or more episodes. Acceleration of tachycardia by pacing occurred in 10 patients in 5% of episodes. Only two of these patients had experienced acceleration of previously induced arrhythmia. Five patients had spontaneous fast ventricular tachycardia or fibrillation treated by cardioversion or defibrillation. Spurious treatment was delivered in nine patients (30%), during atrial fibrillation in five, sinus tachycardia in two, and because of fracture of the sensing lead system in two patients. The retrieval of stored intracardiac electrograms was of clinical value in assessing spurious treatment. CONCLUSIONS: Tiered treatment was effective in terminating recurrent ventricular arrhythmias in these selected patients. Most episodes were treated successfully by pacing, and resistant tachycardias, pacing induced acceleration, or haemodynamically compromising arrhythmias were treated by shocks.

Adolescent↗
PubMed1989

Cellular electrophysiology and beta-adrenergic-blocking activity of dilevalol, the R,R-isomer of labetalol, on isolated canine cardiac tissues.

Dilevalol is a beta-adrenergic receptor-blocking drug derived from labetalol. Many beta blockers exert local anesthetic effects or alter repolarization in cardiac tissue. Because the cellular electrophysiologic effects of dilevalol have not been studied, we investigated the actions of dilevalol on canine cardiac tissues using standard microelectrode techniques. We also tested the beta-blocking actions of dilevalol in isolated Purkinje fibers. This was done by measuring the inhibition of the positive chronotropic response to 10(-6) M isoproterenol before and after treatment with the drug. Dilevalol at 10(-9) M produced slight beta blockade, whereas 10(-6) M produced maximal (approximately 90%) effects. In normal Purkinje fibers, dilevalol less than or equal to 10(-6) M did not change the dV/dtmax or action potential duration (APD). Dilevalol at 10(-5) M produced rate-dependent decreases of dV/dtmax, and decreased the plateau amplitude while prolonging total APD of the Purkinje fibers. In ventricular muscle cells, dilevalol greater than or equal to 10(-8) M increases APD, whereas less than or equal to 10(-5) M does not decrease dV/dtmax. Dilevalol less than or equal to 10(-6) M does not decrease automaticity in Purkinje fibers at either the high or the low level of membrane potential. In summary, dilevalol produces significant beta blockade in normal cardiac tissues. The dose-response curve for this action is comparable to that of propranolol. Dilevalol also prolongs APD in ventricular muscle cells. Dilevalol may reduce arrhythmias through either class II or class III effects.

Action Potentials↗
PubMed1988

Automatic and triggered impulse initiation in canine subepicardial ventricular muscle cells from border zones of 24-hour transmural infarcts. New mechanisms for malignant cardiac arrhythmias?

With standard microelectrode techniques, electrical activity of cells in the epicardial border zones of infarcts in the canine heart were studied. Either automaticity or triggered activity (or both) occurred in each of the 12 preparations studied from 24-hour infarcts. One 24-hour preparation had continuous activity indistinguishable from low-potential (abnormal) automaticity. This automaticity was not effected by flecainide 1-5 mg/l. Two other 24-hour subepicardial muscle preparations also were automatic. However, nine preparations from the subepicardium were not automatic during superfusion with standard Tyrode's solution. Delayed afterdepolarizations (DADs) and triggered activity could be induced in all of these preparations by treatment with catecholamines. The amplitude of these DADs was directly related to the stimulus rate of the train of impulses used to elicit them, and their coupling interval was inversely related to this rate of stimulation. Triggered activity occurred from maximal diastolic potentials of -58 to -88 mV in the 24-hour infarct zone preparations. In seven preparations from 72-96-hour infarct zones, the epicardial muscle cells did not show triggered activity after treatment with catecholamines. In one preparation from a 72-hour infarct, however, 3-5-mV DADs occurred. No DADs or triggered impulses occurred in subepicardial muscle from normal, noninfarcted hearts. Thus, triggered impulses and low-potential automaticity could contribute to arrhythmias occurring in the canine heart 24 hours after coronary ligation.

Animals↗
PubMed1987

Indecainide compared with quinidine for chronic stable ventricular arrhythmias secondary to coronary artery disease or to cardiomyopathy.

Indecainide, a new type Ic antiarrhythmic agent, and quinidine sulfate were compared in a randomized double-blind parallel study. Cardiac patients with greater than or equal to 30 ventricular premature complexes per hour hour received indecainide, 50 mg, or quinidine, 200 mg every 6 hours, and the doses were increased until more than 80% suppression was noted, adverse effects occurred or a maximal dose of 100 mg of indecainide or 400 mg of quinidine given every 6 hours. Efficacy was achieved in 8 of 10 taking indecainide (p less than 0.05) and 7 of 9 taking quinidine (p less than 0.05). At least 90% of episodes of ventricular tachycardia were suppressed in 4 of 7 patients taking indecainide and 1 of 4 taking quinidine. No adverse effects were observed in the 7 patients who responded to indecainide and the 4 who responded quinidine, resulting in short-term efficacy without adverse effects in 7 patients (70%) taking indecainide and 4 (44%) taking quinidine. The effective or maximal mean daily indecainide and quinidine doses were 190 +/- 32 mg and 1,022 +/- 291 mg, respectively; mean trough indecainide and quinidine concentrations were 617 +/- 247 ng/ml and 3.3 +/- 1.4 micrograms/ml, respectively. Indecainide prolonged mean PR and QRS intervals (p less than 0.05), but not QT and QTc intervals. Quinidine did not change PR or QRS intervals but prolonged QTc interval (p less than 0.05). During dosing, 1 patient discontinued indecainide treatment because of nausea; 3 discontinued quinidine because of gastrointestinal complaints.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Arrhythmia Agents↗