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Biomedical subjects

R Holtzman

Publications and source records attributed to R Holtzman.

7 recordsLinked to original sources
PubMed1991

The effects of labetalol and prazosin on exercise haemodynamics in hypertensive patients.

The antihypertensive and haemodynamic effects of labetalol were compared with those of prazosin both at rest and during bicycle exercise in 38 moderate to moderately severe hypertensive patients (supine DBP 95 to 119 mmHg when untreated). Following a two week open placebo phase to establish baseline BP and baseline exercise performance, patients were randomly and double-blindedly assigned to receive labetalol or prazosin. Drug dose was titrated from 100 to 400 mg labetalol twice daily, or from one to 10 mg prazosin twice daily at weekly intervals until BP was controlled (supine DBP less than or equal to 90 mmHg with at least a 10 mmHg decrease from baseline). Eighteen labetalol and twenty prazosin patients achieved BP control and were subsequently reexercised to fatigue on a bicycle ergometer. The mean changes from baseline for heart rate and rate pressure product (heart rate x SBP) were reduced only in the labetalol group; the difference between the labetalol and prazosin groups was significant (P less than 0.01) both at rest and during exercise. This haemodynamic profile of labetalol may be important in selecting a vasodilating antihypertensive for patients with concomitant ischaemic heart disease.

Adult↗
PubMed1987

Repeat colonoscopy after endoscopic polypectomy.

The records of all patients undergoing endoscopic polypectomy between December 1979 and December 1982 were reviewed. One hundred seventy-two patients underwent colonoscopic polypectomy in the absence of carcinoma or inflammatory bowel disease. Of these, the polyp could not be retrieved in 4, and 19 were lost to follow-up. One hundred forty-nine patients underwent subsequent endoscopy from one to four years after the initial polypectomy. Seventy-five (50.3 percent) of the patients developed new polyps. Although 61 of the 75 patients with new polyps were identified in the first two years, new polyps were noted throughout all four years. The presence of multiple polyps on the initial examination was statistically significant in predicting new polyps. The age and sex of the patients, size of the polyps, and the presence of atypia did not identify patients at higher risk for new polyps. The data indicate that new polyps are more likely to develop in patients who had a previous polyp. It would appear that annual examinations should be performed until two successive examinations are negative. Following a second negative examination, reexamination at two- or three-year intervals, unless symptomatic, would appear to be adequate.

Adenoma↗
PubMed1985

Autonomic dependence of ventriculoatrial conduction.

To evaluate the effects of isoproterenol and atropine on patients with poor ventriculoatrial (VA) conduction, 17 patients were studied who did not have 1-to-1 VA conduction during ventricular pacing at a rate slightly faster than sinus rate (group I) and 11 patients were studied who had 1-to-1 VA conduction, but only at constant ventricular pacing cycle lengths longer than 600 ms (group II). Isoproterenol infusion at a rate causing a 20 to 30% increase in sinus rate or up to 4 micrograms/min shortened the ventricular pacing cycle lengths that induced VA block in all group II patients. Atropine administration at a dose causing a 20 to 30% increase in sinus rate or up to a total dose of 2 mg also shortened the ventricular pacing cycle lengths that induced VA block in all group II patients. At similar pacing cycle lengths, isoproterenol and atropine induced shorter VA intervals than control. Nine of 17 group I patients had demonstrable 1-to-1 VA conduction either during isoproterenol infusion or after atropine administration. Of these 9 patients, 1-to-1 VA conduction could be found only during isoproterenol infusion in 3 patients and only after atropine administration in 4 patients. The improvement of VA conduction by these drugs was related to their effects on the atrioventricular node. The change in VA conduction mediated by autonomic changes induced by these drugs may explain why some patients without demonstrable VA conduction during rest may have, under certain circumstances, "endless-loop" tachycardia or paroxysmal supraventricular tachycardia using atrioventricular nodal conduction as the retrograde limb.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effect of labetalol on exercise tolerance and double product in mild to moderate essential hypertension.

Maximal exercise capacity after control of resting blood pressure with labetalol was studied in nine hypertensive men aged 34 to 69 years (average 52 years). Subjects exercised to exhaustion on an upright cycle ergometer with workload increased as a step function by 25 watts every three minutes, both before and after control of blood pressure was obtained. Mean exercise capacity expressed as total time of exercise until exhaustion was 936 seconds prior to control of the resting blood pressure and 884 seconds (no significant difference) after control of resting blood pressure with labetalol. Double product at peak exercise fell from 254 X 10(2) mm Hg beats per minute prior to blood pressure control to 183 X 10(2) mm Hg beats per minute (p = 0.006) after control of blood pressure with labetalol. The difference in the means of resting heart rate and both peak blood pressure and peak heart rate with exercise were all statistically significant after control of blood pressure with labetalol. These findings suggest that labetalol has an ideal exercise profile affording a cardioprotective effect by decreasing double product but without sacrificing exercise capacity.

Adult↗
PubMed1985

Quantitative analysis of the high-frequency components of the signal-averaged QRS complex in patients with acute myocardial infarction: a prospective study.

We performed a prospective study of the high-frequency components of the terminal portion of the QRS complex in 50 patients with acute myocardial infarction (AMI) (mean age 63 +/- 10 years) within 3.25 +/- 2.45 days of the acute event. Signal averaging (400 beats) at a filter setting of 80 to 300 Hz was performed and the duration of the low-amplitude signals of less than 40 microV in the terminal portion of the QRS, the root-mean-square (RMS) voltage of the terminal 40 msec of the QRS complex, and the total duration of the signal-averaged QRS vector complex were measured. The low-amplitude signals were abnormally prolonged in 22 of 50 patients (44%); the RMS-V was abnormal (less than 20 microV) in 21 of 50 patients (58%), and the signal-averaged vector complex was abnormal (greater than 120 msec) in 15 of 46 patients (33%) without bundle branch block. There was no significant correlation between any of the signal-averaged parameters and site of AMI or total creatine kinase (CK) and CK-MB values. On the basis of the occurrence of spontaneous ventricular tachycardia in the acute and postcoronary care phase of AMI, the patients were divided into two groups. Group I consisted of 31 patients (62%) who had no documented ventricular tachycardia and group II consisted of 19 patients (38%) who had one or more runs of ventricular tachycardia. Fourteen of the 19 patients in group II (73.6%) had nonsustained ventricular tachycardia and five patients (26.3%) suffered sustained ventricular tachycardia/ventricular fibrillation or sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗