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Biomedical subjects

H N Neufeld

Publications and source records attributed to H N Neufeld.

At least 163 records · Page 9Linked to original sources
PubMed1978

Coronary artery disease in children.

In this paper an attempt has been made to correlate the morphologicla aspects of childhood atherosclerosis. Some of the features described are directly related to atherosclerosis. Some of the other conditions described may be related to the subsequent development of atherosclerosis by damaging the vessel wall and thus stimulating the production of atherosclerosis. In other instances, as in the description of the ultrastructural features of the coronary arteries, the exact role of the changes described still remains to be elucidated.

Child↗
PubMed1978

Ventricular reentry and automaticity in myocardial infarction. Effect of size of injury.

The effects of the size of acute myocardial infarction on ventricular reentry and automaticity were studied in 36 mongrel dogs. Large transmural myocardial infarctions were produced by ligation of the left anterior descending coronary artery (major ligation; diameter of infarction above 4.0 cm), and small subendocardial or intramural infarctions were produced by ligating a small diagonal branch of the left anterior descending coronary artery (minor ligation; diameter of infarction less than 1.5 cm). Reentrant arrhythmias were induced by rapid ventricular stimulation, and ventricular automaticity was determined during vagal stimulation. Ventricular automaticity became enhanced only 30 to 45 minutes after both major and minor coronary arterial ligations; however, the animals with major ligations attained a higher level of increased automaticity. While automaticity became enhanced in both groups reentrant arrhythmias could never be produced artificially (or observed spontaneously) in the animals with myocardial infarctions. The dependence of the so-called reentrant arrhythmias on the size of the infarction is a major support for the theory of reentry as the basis for these arrhythmias.

Animals↗
PubMed1977

Current problems in cardiology.

Many achievements in medicine in general, and in cardiology in particular, are the result of joint endeavors by cardiologists, surgeons, research workers and engineers. This paper deals briefly with some of the devices which have been developed as a result of this interdisciplinary cooperation. They included cardiac pace-makers, the use of computers in the analysis of electrocardiograms and echocardiograms in intensive coronary care units (ICCU) and in catheterization laboratories. Finally, the use of an intra-aortic balloon pump and other cardioassist devices will be mentioned. The joint efforts of medical and engineering workers have helped to improve diagnosis of acute myocardial infarction and to improbe techniques and results of cardiac surgery. Finally, it is anticipated that through this combined work, more intensive epidemiologic studies will be made possible, new risk factors uncovered with analysis of their significance - all of which will ad to the prevention of heart diseases.

Biomedical Engineering↗
PubMed1977

Surveillance of pacemaker patients by an automatic pacemaker function analyzer.

An external, simply operated, fail-safe, automatic pacemaker function analyzer (PFA) has been designed for routine examination of ambulatory patients in local medical clinics and for continual surveillance of hospitalized patients in cardiology units. The instrument provides a comprehensive test of the pacing system, including the battery, pulse generator, and electrodes (leads), during varying heart activity. In the recorded ECG from 92 pacemaker patients, the PFA recognized all but 0.29% of the QRS complexes and 0.21% of the pacing artifacts; no signals were incorrectly attributed to the QRS complex. With the PFA, 1171 pacemaker tests were performed on these patients. In all cases, the PFA judged the performance of the tested pacemakers in accordance with the predetermined criteria. The PFA can be integrated into a pacemaker-patient surveillance system within a general-purpose cardiac care unit.

Electrocardiography↗
PubMed1977

The human coronary microcirculation: an electron microscopic study.

The ultrastructure of the terminal vascular bed of human coronary arteries was studied in the myocardial tissue obtained at surgery from different locations in the heart in five patients. The following vessels were identified: (1) Arterioles; slender and prolonged endothelial cells, flat nuclei and two to three layers of smooth muscle cells. (2) Precapillary sphincters: short endothelial cells, large nuclei bulging into the lumen, close myoendothelial junctions and a single layer of circular smooth muscle. (3) Capillaries: composed of one or more slender endothelial cells. (4) Venules: flat endothelial cells and nuclei, no muscular layer, rich collagen tissue. The function of these structures is believed to be as follows: the arterioles are the smallest blood-distributing arteries in the heart. The precapillary sphincters control blood flow to the capillaries; pressor substances present in the blood are picked up by endothelial cells, pass rapidly through the myoendothelial junctions and cause contractions of the smooth circular muscle layer; the bulging nuclei of endothelial cells then passively obstruct the lumen almost completely. The main exchange of gases and nourishing substances takes place in the capillaries. We postulate that in some pathologic conditions, abnormal constriction of the sphincters may cause diminished flow and be the basis for some well defined or unclear ischemic events.

Coronary Circulation↗
PubMed1977

Isorhythmic Dissociation--a "physiological" arrhythmia.

The behavior of the sino-atrial mechanism in isorhythmic dissociation (IRD) was studied in 21 patients, nine with spontaneous IRD and 12 with artificially pacemaker-induced IRD following electrode placement for heart block. Successive P-P, R-R and P-R intervals and blood pressure (BP) fluctuations were determined and graphically interrelated at control and during IRD. Several features were observed: a. IRD was present only when the independent ventricular rate was close to the atrial; b. P rate oscillations closely followed the P-R interval-dependent BP fluctuations (mean difference 30 mmHg) during IRD. In cardiogenic shock and in severe hypertension IRD could not be achieved easily; c. While during complete dissociation or during 1:1 A-V conduction the sinus rate was remarkably constant (2-4 beats/min variations), it showed marked oscillations (differences of 6-19, mean 13, beats/min) during IRD. All the data and calculations support the theory that in most instances of IRD, the arrhythmia is sustained by the normal physiologically active baroreceptor reflex arc.

Aged↗
PubMed1977

Cerebral arteriovenous fistula causing congestive heart failure in infancy.

The case of a newborn female in congestive heart failure due to a cerebral A-V fistula is presented. The cardiac manifestations in the presence of this condition are described, and the diagnostic importance of auscultation of the skull is stressed. Because of the precarious condition of most of these neonates, diagnostic procedures should be minimized if the clinical picture is compatible with this diagnosis, and cerebral angiography should be performed before any heart studies are undertaken.

Female↗
PubMed1977

Isoenzymes of creatine phosphokinase in acute myocardial infarction.

Serial determinations of creatine phosphokinase (CPK) isoenzymes were performed in 400 patients with definite acute myocardial infarction (AMI). The findings were correlated with the clinical course and the findings in another 300 cases of increased CPK levels. MB-CPK, the cardiac fraction, was present in all 400 cases of AMI and in only 5 cases of the 300 patients with high CPK due to causes other than AMI. Based on the magnitude and time course of the total CPK in relation to the MB-CPK, five different patterns are described which correlate with the clinical course. Our findings thus suggest that the determination of CPK isoenzymes can be a most helpful diagnostic tool in the care of the cardiac patient.

Acute Disease↗
PubMed1977

Arteriosclerotic aneurysm of the coronary artery.

The findings in a patient with an angiographically proven aneurysm of the coronary artery are described. The case is reviewed in the light of 115 similar cases reported in the literature. The patient had had numerous episodes of variant angina, a feature not previously described in coronary arterial aneurysms, which may be related to embolic showers originating from the aneurysm.

Adrenergic beta-Antagonists↗