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S Bekheit

Publications and source records attributed to S Bekheit.

At least 19 recordsLinked to original sources
PubMed1990

Use of heart rate spectral analysis to study the effects of calcium channel blockers on sympathetic activity after myocardial infarction.

We used spectral analysis of heart rate variability (HRV) to study the effects of the calcium channel blockers diltiazem and nifedipine and the beta-blocker metoprolol on the sympathetic nervous system in patients following myocardial infarction. Energy in the low-frequency range (0.04 to 0.12 Hz) in the standing (tilt) position was used as a quantitative index of sympathetic activity. Twenty-seven male patients, mean age 62 +/- 13 years, were studied 2 to 6 weeks after myocardial infarction. Eight patients received metoprolol, 100 mg twice daily; nine patients received diltiazem, 60 mg three times daily; and 10 patients received nifedipine, 10 mg three times daily. HRV and arterial blood pressure were recorded before and 5 to 7 days after initiation of therapy. None of the drugs had significant effects on the systolic blood pressure, and only nifedipine significantly reduced the diastolic blood pressure. Metoprolol and diltiazem reduced the low-frequency HRV in all patients studied, but nifedipine had no consistent effects. Our results suggest that diltiazem had a depressant effect on sympathetic activity similar to beta-adrenergic blockers. This effect was not observed with nifedipine. The reduction in sympathetic activity by diltiazem may contribute to its therapeutic effects in the post-infarction period.

Adult↗
PubMed1990

Risk stratification and management of patients with organic heart disease and nonsustained ventricular tachycardia: role of programmed stimulation, left ventricular ejection fraction, and the signal-averaged electrocardiogram.

PURPOSE: Programmed stimulation, left ventricular ejection fraction, and signal-averaged electrocardiography were performed in patients with organic heart disease and spontaneous nonsustained ventricular tachycardia (VT) to determine the role of these techniques in risk stratification and management. PATIENTS AND METHODS: The study consisted of 90 patients: 63 had coronary artery disease and 27 had idiopathic dilated cardiomyopathy. Radionuclide ventriculography, signal-averaged electrocardiography, and programmed electrical stimulation were performed in all patients within 48 hours of index ambulatory electrocardiography. RESULTS: Fifty-three patients (59%) had an ejection fraction less than 40%. Programmed stimulation induced sustained monomorphic VT in 22 patients (24%), ventricular fibrillation (VF) in 10 patients (11%), and no sustained VT/VF in 58 patients (64%). The signal-averaged electrocardiogram (ECG) showed late potentials in 23 patients (26%). Sustained monomorphic VT could be induced in 65% of patients with late potentials and in 10% of those without late potentials. There was no case of inducible sustained monomorphic VT in 33 patients with no late potentials and an ejection fraction of 40% or greater. All patients with induced sustained monomorphic VT received antiarrhythmic therapy guided by the results of programmed stimulation. All 58 patients with no induced sustained ventricular tachyarrhythmias and eight patients with induced VF were discharged without receiving antiarrhythmic drugs. During a follow-up of 30 +/- 10 months, the three-year sudden death rate was 19% in patients with induced sustained VT, 0% in those with induced VF, and 9% in those with no induced sustained VT/VF. The three-year sudden death rate was the same (7%) in patients with no induced sustained VT/VF, both in those with an ejection fraction of 40% or greater or less than 40%. On the other hand, the three-year total cardiac mortality was significantly higher (27%) in those patients with ejection fractions less than 40% compared to those with ejection fractions of 40% or greater (7%). CONCLUSION: It is concluded that the signal-averaged ECG, ejection fraction, and programmed stimulation could be used for the risk stratification and management of patients with organic heart disease and nonsustained VT as follows: (1) Patients with no late potentials and with an ejection fraction of 40% or greater do not require invasive evaluation or antiarrhythmic therapy, since the incidences of induced VT and sudden death are very low. (2) Patients with late potentials as well as patients without late potentials but with an ejection fraction of less than 40% may be advised to undergo electrophysiologic evaluation.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Arrhythmia Agents↗
PubMed1989

Prognostic significance of the signal-averaged ECG depends on the time of recording in the postinfarction period.

Serial recordings of the signal-averaged ECG and the 24-hour ambulatory ECG were obtained from 156 patients with acute myocardial infarction up to 5 days (phase 1), 6 to 30 days (phase 2), and 31 to 60 days (phase 3) after the infarction. Left ventricular ejection fraction by radionuclide ventriculography was also determined in phase 2. The signal-averaged ECG was abnormal during one or more of the three phases in 51 patients (31%). In 35 of these patients (69%) the recording changed category between normal and abnormal with the highest prevalence of abnormal recording occurring during phase 2. Eight patients had ventricular tachycardia/ventricular fibrillation in the first 48 hours after myocardial infarction. The signal-averaged ECG was abnormal in only one of these patients. Twelve patients had late arrhythmic events during the first year of follow-up (four sudden deaths and eight instances of documented ventricular tachycardia or ventricular fibrillation). Nine of the 12 patients had an abnormal signal-averaged ECG in phase 2 and four of these nine had a normal recording in phase 1. Five patients had a transient abnormal signal-averaged ECG in phase 1, whereas six patients had an abnormal recording only in phase 3. None of these 11 patients had an arrhythmic event. Stepwise logistic regression showed that an abnormal signal-averaged ECG in phase 2 has the most significant relation to late arrhythmic events. Both an abnormal signal-averaged ECG and a left ventricular ejection fraction less than 40%, but not complex ventricular arrhythmias, were independent significant risk factors for late arrhythmic events.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Initiation of ventricular fibrillation by supraventricular beats in patients with acute myocardial infarction.

The role of supraventricular extrasystoles in the initiation of ventricular arrhythmia was studied in 72 consecutive patients who developed primary ventricular fibrillation during the acute phase of myocardial infarction. In six patients (8%), a total of 12 episodes of ventricular fibrillation and 16 episodes of ventricular tachycardia were initiated by supraventricular extrasystoles. Ventricular fibrillation and tachycardia were initiated by single supraventricular extrasystoles in 16 and by salvos greater than or equal to two beats in 12 episodes. The RR coupling interval of the supraventricular impulse immediately preceding ventricular tachycardia ranged from 240 to 420 ms (mean 356 (62)) and was characteristic of R-on-T (prematurity index less than 1) in 63% of episodes. Average peak serum creatine kinase activity in the six patients in whom ventricular tachycardia was initiated by a supraventricular extrasystole was 1275 units compared with 720 units in the remaining 66 patients. Five of these six patients later showed evidence of pump failure. Lignocaine or procainamide or both suppressed the ventricular arrhythmia in five of the six patients. The initiation of ventricular fibrillation or tachycardia by supraventricular extrasystoles in acute myocardial infarction is not uncommon and may reflect the increased vulnerability of the heart after a large infarct. These arrhythmias may respond to drugs that suppress ventricular irritability.

Cardiac Complexes, Premature↗
PubMed1987

The prediction of cardiac risk in patients undergoing vascular surgery.

In an attempt to determine whether noninvasive cardiac testing could be used to assess cardiac risk in patients undergoing surgery for vascular disease, the authors studied 96 patients. Seventy-seven patients eventually underwent major vascular surgery with 11 (14%) experiencing a significant cardiac complication. Thallium imaging was much more likely to be positive (p less than 0.01) in patients with a cardiac complication; however, there was a significant number of patients with cardiac complications who had a positive history or electrocardiogram for myocardial infarction. When grouped by complication and history of infarction, thallium imaging, if negative, correctly predicted low cardiac risk in the group with a history of infarction. Thallium imaging, however, did not provide a clear separation of risk in those without a history of infarction. Age and coronary angiography, on the other hand, did reveal significant differences within the group without a history of infarction. The resting radionuclide ejection fraction followed a similar pattern to thallium imaging. It is concluded that a positive history of myocardial infarction at any time in the past is the strongest risk predictor in this population and that the predictive value of noninvasive testing is dependent on this factor. Considering these findings, a proposed scheme for assessing risk that will require further validation is presented.

Age Factors↗
PubMed1979

Massive coronary arterial aneurysm.

The pathologic and echocardiographic findings of a massive right coronary arterial aneurysm in a 62 year old man are presented. The thrombosed aneurysm simulated a cardiac tumor, destroying one pulmonary valve cusp. It also caused marked pulmonary stenosis with elongation and narrowing of the outflow tract of the right ventricle and fixation of half of one cusp of the tricuspid valve.

Aneurysm↗
PubMed1979

Severe pulmonary vascular disease in systemic lupus erythematosus.

A young woman with systemic lupus erythematosus (SLE) had clinical evidence of acute cor pulmonale. Autopsy disclosed vascular lesions in the lungs resembling those seen in advanced pulmonary hypertension. This case illustrates that severe pulmonary vascular disease may complicate SLE and mimic pulmonary thromboembolic disease.

Acute Disease↗
PubMed1976

The effects of smoking on myocardial conduction in the human heart.

Inhalation of a few puffs on a cigarette increases the velocity of conduction and shortens the effective refractory period of the A-V node. These effects are attributed to adrenergic stimulation produced by minute amounts of nicotine absorbed. Wenckebach block is abolished whether induced by atrial pacing or occurring spontaneously. Conduction velocity in the His-Purkinje system and in the anomalous pathways in the WPW syndrome were not affected. Smoking increases the ventricular rate in atrial fibrillation, and antagonizes the cholinergic effects of digitalis.

Atrial Fibrillation↗
PubMed1976

Angular velocity of the QRS loop of the vectrocardiogram in the normal heart.

Angular velocity expressed in radians/sec of the rotation movement of the QRS loop at intervals of 2.5 msecs was calculated from a computer program written in Fortran IV. Frontal, horizontal and left sagittal planes were recorded in 125 normal subjects for analysis. The range of angular velocity for 375 QRS loops was from a few radians/sec to a maximum of 95 radians/sec. Average values of maximum angular velocities were: frontal plane, 46.2 radians/sec, horizontal plane, 41 radians/sec, and left sagittal plane, 34.1 radians/sec. Angular velocity expressed as a periodic function of the vector loop is characterized by polyphasic curves. In the frontal plane, curves tend to be more symmetrical with maximum values in the middle. Angular velocity curves are an alternate expression of analysis of planar vector loops employed in clinical practice. Their normal ranges are given in this paper.

Adult↗