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Biomedical subjects

J M Matloff

Publications and source records attributed to J M Matloff.

At least 109 records · Page 6Linked to original sources
PubMed1983

Coronary artery stenoses. Relationship between angiographic severity and impact on mean diastolic pressure gradient.

Coronary angiography provides important anatomic information about coronary artery stenoses. However, it is unclear whether specific assumptions about hemodynamic impact can be made from the angiogram. We therefore studied the relationship between angiographic severity of coronary stenoses and the mean diastolic pressure gradient measured directly at coronary bypass operation. We studied 29 stenoses selected because they were the only lesions in a given vessel, they were well seen in two angiographic views, and there was no change in clinical status of the patient between angiographic and surgical procedures. Fourteen stenoses were in the left anterior descending artery, nine were in the right coronary artery, and six were in the left circumflex artery. Correlation between mean diastolic gradient and percent stenosis was good (r = 0.78, p = 0.001) and especially so for lesions in the left anterior descending artery (r = 0.84, p = 0.001). Lesions over 90% had a wide range of gradients, while lesions less than 90% tended to have more predictable gradients. Collaterals invariably identified vessels with stenoses causing major pressure gradients. History of myocardial infarction was associated with major gradients in supplying vessels. Length of stenosis was not an important influence on gradient over a stenosis. We conclude that in some defined instances, generalizations about hemodynamic (and presumed functional) impact of stenoses can be made from the angiographic assessment, but precise assumptions are not possible.

Adult↗
PubMed1983

Arrhythmias and conduction disturbances following cardiac operation for the removal of left atrial myxomas.

Between September, 1971, and April, 1982, 11 patients (seven female) with left atrial myxomas underwent surgical resection at Cedars-Sinai Medical Center. The tumors ranged in size from 4 to 9 cm (mean 6.3 cm) and were attached to the interatrial septum (four superiorly, four inferiorly), the free atrial wall (one posteriorly, one at the dome), or both (one). Although all patients were symptomatic preoperatively, arrhythmias were uncommon; only one had chronic atrial fibrillation, and two others had had single episodes of paroxysmal atrial fibrillation in the immediate preoperative period. Early postoperatively, all but one patient had episodes of atrial fibrillation (eight patients), atrial flutter (four patients), junctional rhythm (six patients), sinus arrest (two patients), or complete heart block (three patients). Ten patients required antiarrhythmic therapy, and two required permanent pacemaker implantation. After a mean follow-up of 48 months (range 7 to 124), seven patients continue to have episodic or chronic supraventricular arrhythmias, with only three patients not using antiarrhythmic drugs regularly. The pathophysiological basis for these arrhythmias is unclear, but some patients appear to have sustained injury to the sinus node or atrioventricular node, while others have developed interatrial or intra-atrial conduction delays. Attention should be directed to the basis of these arrhythmias and conduction disturbances, as surgical technique may be the major determinant of this early and late postoperative complication.

Adult↗
PubMed1983

Post-myocardial infarction ventricular septal defect. Improved outlook.

Eight patients (mean age 63.75 years) were operated upon for post-myocardial infarction ventricular septal rupture (PMI-VSD) within 1 to 21 days of the infarction and 8 hours to 18 days of rupture. All but one were in low cardiac output syndrome necessitating intra-aortic balloon pumping; all had cardiac catheterization. The VSD was closed via a transinfarct ventriculotomy with an oversized folded double patch, the folded edge being incorporated in the ventriculotomy closure. Five patients received seven saphenous vein coronary bypass grafts. None had recurrent shunts. Six patients (anterior VSD, five; posterior VSD, one) are survivors (18 months to 2.5 years) in Class I (five) or Class II (one). Two patients died postoperatively, one (anterior VSD) of an arrhythmia and the other (posterior VSD) while on biventricular bypass support. Two survivors in whom prolonged preoperative stabilization was attempted required emergency operation before the planned waiting period of 3 weeks had elapsed, and both had postoperative multiorgan complications. Our present approach is to operate as soon as clinical and catheterization diagnosis of VSD is made.

Aged↗
PubMed1982

Effects of calcium on the coronary and systemic circulation in patients after coronary surgery.

Nine patients were studied three hours after aorto-coronary bypass. Before anaesthesia a radial arterial cannula was inserted and a thermodilution catheter placed into the pulmonary artery by fluoroscopy. A special thermodilution catheter was manipulated into the coronary sinus. Haemodynamic measurements were made plus cardiac output and coronary sinus blood flow. Content of oxygen and lactate in arterial and coronary sinus blood was determined. Series of measurements were done before and after 1 gm of CaCl2 given intravenously over 15 minutes. Calcium increased cardiac index and arterial pressure but not systemic vascular resistance. Total coronary sinus blood flow did not change, nor did myocardial oxygen consumption or coronary sinus oxygen content. Content of lactate in arterial and coronary sinus blood was unaltered and lactate extraction by the heart continued, in eight of nine patients. The improved haemodynamics were accomplished without inordinate risk to global ventricular energy metabolism.

Blood Circulation↗
PubMed1982

Role of intravenous verapamil in supraventricular tachyarrhythmias after open-heart surgery.

Although the antiarrhythmic effects of verapamil (V) have been studied widely, its role in the treatment of atrial tachyarrhythmias after open-heart surgery (OHS) has not been defined. Accordingly, 22 patients were studied using a double-blind randomized crossover protocol 1 to 6 days after OHS, except for one patient, who was studied 90 days after OHS. Atrial fibrillation was seen in 18 and atrial flutter was observed in four patients. Two doses were used, 0.075 and 0.15 mg/kg (not exceeding 10 mg per dose), depending on the response. A positive response consisted of: conversion to sinus rhythm or heart rate less than 100 beats/minute (bpm). Eleven patients received V as the first drug; the remaining 11 received placebo first. Digoxin had been given to 20 patients (0.5 mg average dose) prior to inclusion in the study. Four patients converted to sinus rhythm within 30 minutes after V and one additional patient did so within 10 seconds of placebo administration. The post treatment heart rate combining both low and high dose response was 85 +/- 18 compared to 128 +/- 23 bpm for placebo (M +/- SD, p less than 0.01). The heart rate remained lower than control 30 minutes after V. Transient hypotension required intravenous fluid in one patient. Thus, V safely and rapidly controls heart rate but is not likely to result in immediate conversion to sinus rhythm in patients after OHS.

Adult↗
PubMed1982

Flow characteristics of the St. Jude prosthetic valve: an in vitro and in vivo study.

The St. Jude cardiac prosthetic aortic valve was evaluated in vitro and in vivo in an attempt to establish flow characteristics and to correlate them with clinical findings. In vitro, a fluid vehicle (6% Polyol V-10, 32 degrees C) with viscosity similar to blood (0.035 dyne-sec/cm2) was used under conditions of steady flow through a flow chamber simulating the aortic root. Gradient, velocity, and shear stress were measured 5.79 mm, 26.79 mm, 44.79 mm, and 77.79 mm downstream from 25-mm and 27-mm valves using a laser-Doppler anemometer. At 417 ml/sec, the valve gradient was 6.2 mmHg with the 25-mm valve, and 5.2 mmHg with the 27-mm prosthesis. Velocity was maximum at the orifice center, and wall shear stress was low (maximum 600 dyne/cm2). In vivo, six patients with 25-mm St. Jude aortic valves were studied within 48 hours after surgery to determine cardiac output, valve flow, and gradient. The gradient was 3.3 +/- 1.9 mmHg (M +/- SD) at 249 +/- 96 ml/sec and the effective valve area was as large as the geometric area (2.58 vs. 3.09 cm2). Thus, flow through the St. Jude valve is unobstructed and central, has low turbulence, and achieves optimal effective valve area for a given available orifice area.

Aortic Valve↗
PubMed1982

Ruptured atheromatous plaques in saphenous vein coronary artery bypass grafts: a mechanism of acute, thrombotic, late graft occlusion.

Although early occlusion of saphenous vein coronary artery bypass grafts is usually thrombotic, late occlusion is most often a result of progressive intimal fibromuscular proliferation or atheroma formation in the implanted vain. We describe another mechanism of late graft occlusion: atheromatous plaque rupture with superimposed occlusive thrombosis. Four men, ages 48-67 years underwent repeat bypass surgery for recurrent angina. Six of eight vein grafts excised 5-8 years after original bypass showed complete luminal occlusion by recent thrombus superimposed on ruptured atheromatous plaques. Similar findings were present at autopsy in two of three vein grafts from a 66-year-old man who died 7 years after bypass. These lesions are indistinguishable from those that occur in native coronary arteries of many patients with acute myocardial infarction. Unlike previously described graft occlusions, the present lesion represents a mechanism of acute, thrombotic, late graft occlusion. If recognized early, it may be amenable to nonsurgical intervention by angioplasty or thrombolysis.

Acute Disease↗
PubMed1982

Intravenous nitroglycerin and myocardial metabolism during anesthesia in patients undergoing myocardial revascularization.

Although intravenous nitroglycerin has been used to control the hypertensive response during sternotomy in patients undergoing myocardial revascularization, the effects of the drug on myocardial oxygen supply and demand have not been anesthetized for coronary artery bypass, were studied before and after administration of intravenous nitroglycerin (mean dose 12 microgram/kg in 6 minutes). Evaluation of myocardial metabolism showed an increase in coronary sinus oxygen content (p less than 0.05) and a reduction in myocardial oxygen consumption (p less than 0.05). Although mean myocardial lactate extraction and coronary sinus blood flow were not significantly altered in the group as a whole, variations in individual patient responses were observed and are discussed. These direct observations of global myocardial metabolism observed in this study group are similar to the conclusions reached by other investigators using indirect indices of myocardial oxygen supply and demand.

Anesthesia↗
PubMed1982

Myocardial metabolism and hemodynamic responses to halothane or morphine anesthesia for coronary artery surgery.

Eighteen patients having coronary artery bypass grafts were randomly anesthetized with morphine (1 mg/kg) or halothane and oxygen. Central and peripheral pressures were measured serially, plus cardiac output and total coronary sinus blood flow, both by thermodilution catheters, starting before induction of anesthesia and continuing until completion of sternotomy. No significant differences in hemodynamic responses were seen between the two anesthetic techniques during induction: blood pressure and peripheral vascular resistance decreased significantly, but not cardiac output or coronary flow. Myocardial oxygen consumption decreased significantly with induction as oxygen content of coronary sinus blood increased, indicating preservation of oxygen balance. Heart rate and blood pressure increased after sternotomy in the patients given morphine, with the myocardium producing lactate in two of six patients and with nitroprusside being required in four patients to decrease arterial pressure. Halothane-oxygen anesthesia effectively controlled autonomic responses to sternotomy, although one of 12 patients had myocardial lactate production at that time. Neither rate-pressure product or ST segment changes were useful predictors of the ratio between myocardial oxygen consumption and supply. Myocardial oxygen balance can be maintained in coronary patients before cardiopulmonary bypass if pulse rate and blood pressure are kept at less than awake levels.

Adult↗
PubMed1982

Dobutamine and cardiac oxygen balance in patients following myocardial revascularization.

Dobutamine is frequently used in the early postoperative period following myocardial revascularization to improve cardiac output. Seven postoperative adult patients with low output syndrome were studied before and during intravenous dobutamine (mean +/- SD: 5.1 +/- 2.5 micrograms/kg/min) infusion. The metabolic effects were evaluated and related to hemodynamic changes. Cardiac index increased 40% (p less than 0.05) with an increase in heart rate (p less than 0.05) and decreases in systemic vascular resistance and right atrial pressure (p less than 0.05). No significant changes occurred in arterial or pulmonary capillary wedge pressures or in stroke volume index. Dobutamine produced a 29% increased in myocardial oxygen consumption which, in these revascularized patients, was accompanied by a 35% increase in coronary blood flow. No significant alteration was observed in coronary sinus oxygen content or in global myocardial lactate extraction. Thus, despite the increased metabolic cost of dobutamine, global myocardial ischemia was not observed.

Blood Pressure↗
PubMed1982

Effects of left heart bypass on right ventricular function.

Right ventricular function has been studied in a canine ejecting heart model in-situ with intact sympathetic innervation and constant cardiac output, during varying degrees of left heart bypass ratio ranging from nil to total left ventricular decompression. The right ventricular function deteriorates as the left heart bypass ratio increases, reaching the maximal degree of RV depression when the LV is maximally decompressed. Some practical implications for the conduction of left heart bypass are discussed.

Animals↗
PubMed1982

Cardiovascular effects of morphine in patients with coronary arterial disease.

Large doses of morphine sulfate have been reported to cause myocardial lactate production and reduction in coronary blood flow in animals. Similar effects with clinical doses in man would significantly alter the management of cardiac patients. Eleven adult patients with significant coronary arterial disease and normal left ventricular ejection fraction were studied before and 30 minutes after infusion of morphine (0.25 mg/kg IV). Evaluation of myocardial metabolism showed an increase in coronary sinus oxygen content (p less than 0.001) and a reduction in myocardial oxygen consumption. Myocardial lactate extraction was not altered. No change in coronary sinus blood flow was seen. It is concluded that infusion of morphine sulfate, 0.25 mg/kg IV, does not produce global myocardial ischemia in patients with coronary artery disease and normal ventricular function.

Aged↗
PubMed1982

Effects of protamine sulfate on myocardial oxygen supply and demand in patients following cardiopulmonary bypass.

The effect of protamine sulfate on myocardial oxygen supply and demand was studied under clinical conditions in nine patients following cardiopulmonary bypass. Before surgery, the patients had severe coronary artery disease with good ventricular function. The patients required no vasoactive drugs, but only blood volume adjustments when weaned off bypass, and were hemodynamically stable at the time of study. The protamine dose of 196 mg (2.5 mg/kg) was infused over 4 +/- 1 minutes. Although modest variation in hemodynamic function occurred in individual patients after administration of protamine, there were no significant hemodynamic alterations for the group. No significant alteration in global myocardial metabolism was observed. Protamine caused a small decrease in measured coronary blood flow, resulting in a corresponding reduction in calculated myocardial oxygen consumption as coronary sinus oxygen content remained unaltered. Myocardial lactate extraction showed no significant alteration. It is concluded that protamine sulfate, given at rapid infusion rates in hemodynamically stable patients, is not associated with an adverse alteration in hemodynamics or global myocardial metabolism.

Aged↗
PubMed1981

Low cardiac output states after open heart surgery. Comparative hemodynamic effects of dobutamine, dopamine, and norepinephrine plus phentolamine.

The hemodynamic effects of dobutamine, dopamine, and a combination of norepinephrine-phentolamine were compared in nine patients with low cardiac output state after open heart surgery. Using a Latin square design for drug sequence, each patient was given each drug at three levels by continuous intravenous infusion. For dobutamine and dopamine the doses were 2.5, 5.0 and 10.0 microgram/kg/min; for norepinephrine, 0.02, 0.05 and 0.10 microgram/kg/min with phentolamine in the ratio of 1 (norepinephrine) to 2.5 (phentolamine). Dobutamine and dopamine both produced an increase in heart rate, mean arterial pressure, cardiac index, and stroke volume index. Both drugs reduced total pulmonary and systemic vascular resistance in the dose range of 5.0 to 10.0 microgram/kg/min. When the maximum tolerated doses were compared, the drugs equally increased cardiac index and stroke volume index, but dopamine did so at a smaller dose than dobutamine. At equivalent doses, dobutamine tended to produce less tachycardia and vasoconstriction than dopamine. The norepinephrine-phentolamine combination resulted in increases in both systemic arterial pressure and vascular resistance with no significant increase in cardiac index. Its unique feature was its predictable vasopressor response with absence of chronotropic effects and ventricular irritability.

Cardiac Output, Low↗
PubMed1981

Improvement in global and segmental left ventricular function after coronary bypass surgery.

Ventricular function was assessed at rest and during exercise by multiple gated cardiac blood pool scintigraphy before and after coronary artery bypass surgery in 21 patients. Resting left and right ventricular ejection fraction and segmental wall motion were unchanged by surgery. However, the postoperative exercise response of left ventricular ejection fraction (-1 +/- 12% vs 6 +/- 9%) and segmental wall motion score (medium -2.7 [range -8 to 2] vs -0.4 [range -6 to 2]) were significantly improved (p less than 0.05). The normal right ventricular ejection fraction exercise response was maintained after surgery. Previous myocardial infarction in 15 patients did not attenuate the observed improvement in ventricular function. In addition, normal postoperative left ventricular ejection fraction response to exercise was associated with symptomatic improvement. In three of six patients a normal preoperative left ventricular ejection fraction response to exercise was not maintained. Therefore, global and regional left ventricular reserve is improved by coronary bypass surgery and this improvement is not affected by previous myocardial infarction.

Adult↗