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Biomedical subjects

M D Klein

Publications and source records attributed to M D Klein.

At least 109 records · Page 6Linked to original sources
PubMed1982

Treatment of stable angina of effort with verapamil: a double-blind, placebo-controlled randomized crossover study.

The effects of verapamil were assessed in 26 patients with stable exertional angina pectoris in a double-blind, placebo-controlled, randomized crossover protocol using serial treadmill tests. Verapamil, 480 mg/day, reduced anginal frequency from 5.6 +/- 7.3 to 2.2 +/- 3.9 attacks per week (p less than 0.001) and nitroglycerin consumption from 3.4 +/- 4.9 to 1.2 +/- 2.5 tablets per week (p less than 0.05) compared with placebo. Treadmill time increased from 6.4 +/- 2.1 minutes during the placebo phase to 7.5 +/- 1.8 minutes during the verapamil phase (p less than 0.001). Verapamil's beneficial effect appeared to be related, in part, to a 10% reduction of the rate-pressure product at rest (p less than 0.05) and a 12% reduction during submaximal exercise (p less than 0.001). Verapamil also caused less marked ST-segment depressions at peak exercise (p less than 0.05) at a similar rate-pressure product, suggesting a favorable redistribution of coronary blood flow to the ischemic zone. Side effects from verapamil were minimal, consisting mainly of constipation (six patients). Verapamil appears to be a safe and effective drug for treating angina of effort.

Adult↗
PubMed1982

Suppression of ischemic related ventricular tachycardia by verapamil during treadmill exercise testing.

A 35-year-old man with class 2 angina pectoris was enlisted in a serial exercise test protocol to evaluate oral verapamil therapy for angina pectoris. During both the single-blind open dose titration phase and the double-blind phase, short salvoes of ventricular tachycardia (VT) were followed by angina and ischemic ST segment depression during exercise with placebo. With verapamil therapy, no ventricular ectopy was noted during exercise, and the patient exercised longer before angina or ischemic ECG changes developed. Twenty-four hour ECG monitoring revealed multiform ventricular premature depolarizations and three-beat salvoes of VT with placebo and no ventricular ectopy whatsoever with verapamil. Verapamil's antiarrhythmic effect may be secondary to its anti-ischemic action, or, by inhibiting slow channel conduction (with its propensity for enhanced automaticity and reentry) induced by ischemia and the sympathetic response to exercise, exerts a primary antiarrhythmic action.

Adult↗
PubMed1982

Myopotential inhibition of unipolar lithium pacemakers.

The effect of isometric upper extremity exercise on pacemaker function was evaluated in 27 patients who remained pacemaker-dependent during testing. Inhibition was demonstrated in eight (31 percent) of which five were symptomatic. Based on design of the sensing amplifier and return to an all-metal housing in the unipolar lithium pulse generators, myopotential inhibition is being recognized as one cause of symptomatic pacemaker inhibition that is more common than generally appreciated. A method of evaluation and management options for symptomatic patients are discussed. Routine testing of all patients should be performed at the time of a regular office evaluation. If one model pulse generator appears to be particularly prone to myopotential inhibition, this knowledge should be considered in the choice of future pacing systems.

Action Potentials↗
PubMed1982

Neuropsychological dysfunction following elective cardiac operation. I. Early assessment.

Two neuropsychological tests were administered to 227 men and women, ages 25 to 69 years, before and after coronary bypass and cardiac valve operations to provide current information regarding the incidence of postoperative decrements in neuropsychological dysfunction and the factors associated with them. Biographical, psychological, and medical-surgical data were studied together with changes in scores on the Trail Making Tests and the Visual Reproduction (VR) Test of the Wechsler Memory Scale (WMS). Postoperative decrements greater than one standard deviation were observed in each of the four scores derived from these testings for 11% to 17% of the patients. Yet 70% of all patients remained within one standard deviation of original performance on all four scores. Among the preoperative correlates of significantly reduced test performance were age greater than 60 years, end-diastolic pressure greater than 30 mm Hg, moderate to severely enlarged heart size on preoperative x-ray film, and use of propranolol or chlordiazepoxide hydrochloride. Significant perioperative correlates included measure of duration of operation (such as total time of operation greater than 7 hours, time on the pump greater than 2 hours, and aortic cross-clamp time greater than 2 hours), total estimate of blood loss greater than 2,000 ml, hypotension, difficult intubation, and insertion of an intra-aortic balloon. Postoperative factors significantly associated with declines in test scores included electrolyte (Na+, K+, Cl-) abnormalities, longer stay in the intensive care unit, bizarre behavior or disorientation, and depression score. These findings suggest that those patients with more precarious heart function, a more protracted operation, and/or increased metabolic disturbances are especially prone to neuropsychological dysfunction following cardiac operations.

Adult↗
PubMed1981

Congenital defects of the abdominal wall. A review of the experience in New Mexico.

Omphalocele, umbilical cord hernia, and gastroschisis are surgically correctable defects of the abdominal wall. Each of these defects has a distinct embryologic basis that results in a characteristic clinical picture. Twenty-five infants with congenital defects of the abdominal wall were treated at the University of New Mexico Hospital in the past four years. Six infants had omphalocele, one had umbilical cord hernia, and 18 had gastroschisis. Survival among infants who underwent a corrective operation was as follows: omphalocele, 50%; umbilical cord hernia, 100%; and gastroschisis, 82%. Long-term survival for the entire group was 72% (18/25). Gastroschisis, which had a lower incidence of major associated anomalies, had a better prognosis than omphalocele. The mortality of congenital abdominal wall defects was related to presence of severe associated anomalies and to poor clinical condition on admission. Prompt and informed initial care may increase the chance of survival.

Abdominal Muscles↗
PubMed1981

Cellulitis and necrotizing fasciitis of the abdominal wall in pediatric patients.

Soft tissue infections of the abdominal wall in 14 children were classified as cellulitis (8), necrotizing fasciitis (5), or myositis/myonecrosis (1). These 3 categories were characterized by increasing anatomic depth of infection, clinical severity, and need for more radical surgical treatment. Ten of the 14 children were neonates. The most frequent associations were omphalitis (5), necrotizing enterocolitis (4), and urachal anomalies (3). The severest infections were usually polymicrobial and contained both aerobic and anaerobic bacteria. Important clinical findings in children with necrotizing fasciitis and myositis/myonecrosis were tachycardia, systemic toxicity, severe edema, and, in older children, pain out of proportion to the apparent degree of infection. None of the children had fever or crepitation of the wound. An ominous sign, indicative of the need for immediate, radical debridement was the appearance of a patch of dusky or gangrenous skin. There were two deaths associated with delayed diagnosis of necrotizing fasciitis. One child did not receive radical debridement, and the other received it too late to be of benefit. Although these infections are rare in children, their lethal potential and early diagnostic signs must be recognized.

Abdominal Muscles↗
PubMed1981

Studies with a slit-valve catheter for parenteral nutrition.

A new catheter for central venous total parenteral nutrition has a blunt occluded distal end and a longitudinally oriented slit one centimeter proximal. Studies in rats show that this slit-valve prevents both reflux of blood and intracatheter thrombosis. This may be a factor in reducing sepsis associated with central venous total parenteral nutrition.

Animals↗
PubMed1981

Congenital defects of the abdominal wall.

We reviewed a 22 year experience with 138 newborn infants with congenital evisceration through defects of the abdominal wall. Omphalocele is a large defect which always has a sac, in which the rectus muscles insert laterally on the costal margins and which usually has associated anomalies. Cord hernia is a small defect which always has a sac, in which the rectus muscles insert at the xiphoid and which commonly has associated anomalies. Gastroschisis is a small defect which never has a sac, in which the rectus muscles insert at the xiphoid and has few associated anomalies, though prematurity is frequent. We hypothesize that gastroschisis develops because the umbilical coelom fails to form, which forces the elongating midgut to rupture into the amniotic cavity. This differs from the embryogenesis of omphalocele, which is failure of closure of a primary body fold, and from that of cord hernia, which is failure of the midgut to return from the umbilical coelom. The number of infants in this series who survived after surgical repair of an omphalocele was 31 of 51 patients; of a cord hernia, 22 of 28 patients, and of gastroschisis, 40 of 59 patients. Factors contributing to mortality were associated anomalies, low birthweight and surgical closure under excessive tension.

Abdominal Muscles↗
PubMed1981

Nonrefluxing central venous catheters in children.

A central venous catheter occasionally is necessary in infants to maintain adequate nutritional support. Our experience shows that routine dressing changes are not necessary. Clinical studies of a slit-valve central venous catheter in which intraluminal thrombosis is eliminated are described. The combination of minimal dressing manipulation, adequate dressing protection, and the nonrefluxing slit-valve catheter have markedly reduced sepsis rates.

Age Factors↗
PubMed1980

Successful use of a paracorporeal left ventricular assist device in man.

A paracorporeal left ventricular assist device (LVAD) with a capacity to pump 8 L/min of blood was employed in a clinical trial, and this report details the first survivor. A 60-year-old man could not be separated from the pump oxygenator following coronary artery bypass grafting, and, therefore, an LVAD was employed. Almost the entire left ventricular workload was assumed by the mechanical pump so that the myocardium was allowed to rest and recover. The LVAD support was continued for 105 hours. It provided satisfactory total body perfusion with maintenance of good hemodynamics--without serious deleterious effects on hematologic factors. The patient is alive and active without cardiac symptoms 16 months after his operation. The total experience with 13 LVAD implantations warrants continuation of the clinical trials in selected patients.

Angina Pectoris↗