Mark L. Entman

The anatomy and blood supply of the papillary muscles of the left ventricle

Abstract The supply of blood to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base generally receive their vascular supply from separate tributaries which have a radial arrangement. Fibrosis of the papillary muscles is most often associated with occlusive disease of the large coronary vessels. The vascular alteration accompanying this fibrosis is of two types: (1) a fine overgrowth of Class A vessels, without interruption of the Class B vessels, and (2) an interruption of all channels, with enlargement of subendocardial vessels, suggesting the utilization of these vessels in the formation of collaterals past the occluded area.

The vascular supply of the left ventricular wall: Anatomic observations, plus a hypothesis regarding acute events in coronary artery disease☆

Abstract Postmortem injection studies of the left ventricular wall in 58 human hearts have revealed a characteristic distribution of vessels: those which divide quickly (Class A), and those which penetrate to the subendocardial layers, forming multiple anastomosing arcades (Class B). This subendocardial plexus appears to play an important role as a collateral channel in coronary disease. These anatomic features suggest an explanation for certain features observed in patients with coronary artery disease. This concept assigns a permissive role to the large occlusive lesions of the coronary arteries. Such lesions make the potentially ischemic focus distal to the occlusion dependent on collateral flow through the subendocardial plexus, thus permitting dynamic factors that modify this collateral circulation to become critically significant.

Glossopharyngeal Neuralgia Associated with Bradycardia, Syncope, and Seizures

An unusual case of glossopharyngeal neuralgia associated with bradycardia, hypotension, syncope, and seizure is described. Our observations indicate that the cardiovascular components of this syndrome are probably due to stimulation of vagal centers by pain impulses arising from the glossopharyngeal area. Diphenylhydantoin therapy produced satisfactory relief of symptoms in this patient, probably by modification of the intensity of the neuralgic pain and thereby reducing the central vagal response.

The pathologic basis of the electrocardiographic pattern of parietal block

Abstract Extensive pathologic examination of hearts of patients with parietal block and varying clinical pictures indicates that parietal block and left axis deviation can result from a variety of anatomic lesions and that no specific area of the heart or conduction system is consistently involved.

Effects of Hyperbaric Oxygenation on Coronary Artery Occlusion in Pigs

To evaluate more precisely the possible protective effect of hyperbaric oxygenation in experimental myocardial infarction, gradual occlusion of a coronary artery was produced in the pig. Ameroid constrictors designed to produce complete occlusion within 48 hours were placed on the left anterior descending coronary artery of 24 young farm pigs. Of these, 12 were placed in a hyperbaric chamber at 1.25 atmospheres absolute and allowed to breathe 100% oxygen for a maximum of 32 hours. For control studies 12 other pigs were handled in a similar manner outside the chamber while breathing air at normal atmospheric pressure. Pigs treated with hyperbaric oxygenation outlived the untreated pigs. Pathological and histochemical studies of the hearts revealed that pigs treated with hyperbaric oxygenation had a high incidence of myocardial infarction, whereas only two pigs in the untreated group showed any evidence of myocardial damage. These findings suggest that moderate but prolonged hyperbaric oxygenation may lengthen life during and after coronary occlusion. This prolongation of life may permit the development of pathologically detectable myocardial infarctions.

Calcium metabolism in cardiac microsomes incubated with lanthanum ion.

Abstract Lanthanum ion, which has been shown to reverse the polarity of artificial phospholipid membranes and destroy their permeselectivity for calcium ion, did not alter the calcium accumulation or exchange in dog cardiac microsomes. The activity of “calcium-stimulated ATPase” was likewise unaffected. These results suggest that in contrast to artificial membrane systems, microsomal transport of calcium is dependent on a specific and selective site rather than simple electrostatic attraction.

Phasic myocardial blood flow in hemorrhagic hypotension

Abstract The systolic phase of coronary blood flow is markedly impeded in early hemorrhagic hypotension. When pronethalol is administered, it returns to a nearly normal level, and total coronary blood flow is significantly increased. The myocardial lesions that usually occur in hemorrhagic hypotension are markedly reduced by administration of pronethalol regardless of heart rate. These findings demonstrate the role of intense positive inotropic stimulation in the production of myocardial lesions in a situation in which coronary perfusion pressure is decreased.

Effect of Cardiotonic Lactones on Calcium Metabolism of Dog Cardiac Microsomes

The effects of several lactones were studied in a microsomal fraction of dog myocardium thought to be sarcoplasmic reticulum. The lactones increased the steady-state accumulation and turnover of calcium only in the presence of ATP, and augmented the calcium-stimulated ATPase activity. When the effective concentrations of the lactones were exceeded, there were no further alterations in calcium accumulation or turnover. A correlation between the capacity of these lactones to increase calcium accumulation and turnover and their relative cardiotonic activity, as reported in the literature, was noted. The potency of the lactones in relation to calcium metabolism in the microsomes is influenced by ring saturation, position of the double bond, and presence of a steroid ring system to the lactone moiety.

Phasic myocardial blood flow in hemorrhagic hypotension: Effect of beta sympathetic blockade☆

Abstract The systolic phase of coronary blood flow is markedly impeded in early hemorrhagic hypotension. When pronethalol is administered, it returns to a nearly normal level, and total coronary blood flow is significantly increased. The myocardial lesions that usually occur in hemorrhagic hypotension are markedly reduced by administration of pronethalol regardless of heart rate. These findings demonstrate the role of intense positive inotropic stimulation in the production of myocardial lesions in a situation in which coronary perfusion pressure is decreased.