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Biomedical subjects

U Elkayam

Publications and source records attributed to U Elkayam.

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

Improvement of resting myocardial asynergy with cessation of upright bicycle exercise.

Exercise generally aggravates ischemic myocardial dysfunction, presumably by increasing tissue oxygen demand out of proportion to the increase in supply. Nevertheless, resting left ventricular (LV) wall motion abnormalities can improve dramatically after upright exercise. To investigate this "paradoxical" phenomenon, we performed upright bicycle exercise equilibrium radionuclide ventriculography in 93 patients with angiographic coronary artery disease. Immediately after exercise, LV end-diastolic volume was similar to the resting level (1 +/- 22% of rest value), but end-systolic volume (ESV) was significantly below (p less than 0.05) that at rest (-11 +/- 32%) and LV ejection fraction increased significantly compared with rest (0.57 +/- 0.16 vs 0.51 +/- 0.13, p less than 0.05). Improvement in resting myocardial asynergy was frequent (115 of 330 abnormal segments), and was observed more commonly in patients without pathologic Q waves and in segments manifesting mild rather than severe asynergy. In 60 additional patients with resting asynergy who were also studied after nitroglycerin (NTG), there was 89% concordance of wall motion response in asynergic segments after exercise and NTG: 71 of 85 segments manifesting improvement with NTG also improved after exercise, and 157 of 172 segments without improvement with NTG also failed to improve after exercise. Despite the similar wall motion response, the mechanism of improvement is probably different from that produced by NTG. With NTG, preload (end-diastolic volume) and afterload (systolic blood pressure) were significantly lower than their resting control levels (p less than 0.05). These changes did not occur after exercise. Instead, an isolated, significant reduction in ESV was noted. These data support the hypothesis that catecholamine stimulation is responsible for paradoxical wall motion improvement after upright exercise.

Aged↗
PubMed1983

Cardiac output by thermodilution technique. Effect of injectate's volume and temperature on accuracy and reproducibility in the critically Ill patient.

We compared determinations of cardiac output using various combinations of injectate volumes and temperatures to results obtained with 10 ml of iced (0 degrees C) injectate (standard technique) in 33 critically ill patients. The use of a 10-ml injectate at room temperature resulted in comparable reproducibility (12.7 vs 10.8 percent; not significant) and a small and nonsignificant error (-0.013 +/- 0.543 L/min). Five milliliters at room temperature resulted in markedly decreased reproducibility (17.9 vs 8.9 percent; p less than 0.05); however, the error associated with the technique was still not significant (0.136 +/- 0.829 L/min). When a 5-ml injectate at 0 degrees C was used, a reproducibility comparable to that of 10 ml at 0 degrees C was obtained (12.3 vs 7.5 percent; not significant). The results underestimated values obtained with 10 ml at 0 degrees C (-0.360 +/- 0.857 L/minute); however, the difference did not reach statistical significance. The use of 3 ml at 0 degrees C was associated with a substantial increase in variability, with a coefficient of variation of 32.0 percent (10.4 percent for 10 ml of iced injectate; p less than 0.01); however, the differences between the average value of cardiac output obtained with this technique and the standard technique were only minimal (error, -0.063 +/- 0.455; not significant). We reached the following conclusions: (1) the use of 10 ml at room temperature and 5 ml at 0 degrees C as the indicator for thermodilution determinations of cardiac output results in small and insignificant differences in reproducibility and accuracy from the standard technique; (2) five milliliters at room temperature and 3 ml at 0 degrees C are associated with markedly decreased reproducibility; however, the error in values for cardiac output obtained with these techniques is not statistically significant; and (3) the ability to use injectate at room temperature and in small volume should substantially simplify the technique, lowering its cost, and should prevent volume overloading.

Adult↗
PubMed1983

Antiarrhythmic drug therapy during pregnancy.

Pregnancy increases the work demands on the heart by increasing blood volume and thereby cardiac output. Therefore, in pregnant patients with organic heart disease, arrhythmias may have significant hemodynamic consequences to the mother with harm to the fetus. As a result of improved medical therapy, an increasing number of women with cardiac diseases or rhythm disorders reach their reproductive years and require medication. Information on the effect of antiarrhythmic agents on the human fetus as well as the possible changes in therapeutic response during the altered state of pregnancy is limited. In principle, the approach to the treatment of arrhythmias in pregnant patients is similar to that in nonpregnant patients. Special consideration, however, must be given with regard to drug selection and dosage in order to avoid adverse effects on the mother and fetus.

Adrenergic beta-Antagonists↗
PubMed1982

Glyceryl trinitrate (nitroglycerin) ointment and isosorbide dinitrate: a review of their pharmacological properties and therapeutic use.

Sublingual glyceryl trinitrate (nitroglycerin) is the most widely used drug in the treatment of angina pectoris, but its use is limited due to its short acting effect. Recent investigations have shown that some longer acting nitrates administered orally or topically have a long acting antianginal effect. The mechanism of the antianginal effect of nitrates is multifactorial. Nitrates increase oxygen supply to the myocardium by causing redistribution of coronary blood flow. In addition, nitrates decrease myocardial oxygen demand by reducing left ventricular volume, intramyocardial tension, and left ventricular afterload. The use of nitrates for the treatment of congestive heart failure has also been established in recent years. Nitrates have a predominant venodilatory effect resulting in peripheral blood pooling and decreased venous return to the heart, thereby decreasing left ventricular filling pressure. The effect of nitrates on the arteriolar circulation is small, and there is usually little or no change in cardiac output. Some reduction in systemic blood pressure can be seen, while there is usually no change in heart rate. In a small number of patients with myocardial infarction complicated by congestive heart failure, the use of long acting nitrates has resulted in haemodynamic and symptomatic improvement. Nitrates has also bee shown to improve variant angina. Nitrates are usually well tolerated in most patients. However, some troublesome side effects can occur, including headache, postural hypotension, and methaemoglobinaemia.

Angina Pectoris↗
PubMed1981

Comparison of upright and supine bicycle exercise in the detection and evaluation of extent of coronary artery disease by equilibrium radionuclide ventriculography.

Upright and supine multiple gated cardiac blood pool scintigraphy was performed at rest and during maximum exercise in 37 patients, 15 with normal coronary arteriograms, 12 with coronary artery disease (CAD) without myocardial infarction (MI), and 10 with CAD and previous MI. Heart rate and systolic blood pressure were similar during upright and supine exercise in normal patients, but were significantly lower during supine exercise in both CAD groups. Left ventricular (LV) ejection fraction (EF), right ventricular (RV) EF, and LV segmental wall motion were similar in the upright and supine positions at rest or during maximum exercise within each group and showed high concordance of exercise responses. Although LV end-diastolic volume increased in all three groups during upright exercise and in both CAD groups when exercised supine, it did not change during supine exercise in patients without CAD. The fall of LV end-systolic volume in normals was greater during supine exercise than during upright exercise. LV end-systolic volume rose in the CAD patients in both positions. Therefore, although LVEF, RVEF, and LV segmental wall motion responses are similar in the upright and supine positions, LV end-systolic and LV end-diastolic volume changes are not. For detecting and evaluating CAD, the two different positions of exercise appear to have similar diagnostic content.

Coronary Circulation↗
PubMed1981

Dynamic responses to continuous use of prazosin and hydralazine in patients with refractory heart failure.

The hemodynamic effects of oral doses of prazosin and hydralazine were studied in the same group of patients with chronic congestive heart failure. Prazosin, 3 to 10 mg, and hydralazine, 75 to 100 mg, were given by mouth every 6 hr and the responses to the first and the fifth consecutive dose were compared. The first dose of prazosin was followed by a predominant effect of left ventricular filling pressure and concomitantly by reduction of left ventricular afterload. Hydralazine acted primarily on left ventricular afterload with no significant effect on the filling pressure. A marked difference was noted in respect to the dynamic responses to continuous therapy with these two drugs. While the initial hemodynamic effect of prazosin was markedly attenuated in most of the cases after the fifth consecutive oral dose, the response to hydralazine was augmented by continuous therapy. These findings suggest that the reported hemodynamic tachyphylaxis seen with prazosin does not occur with hydralazine when given to the same patients with chronic congestive heart failure. Our study also indicates the importance of prolonged monitoring for the assessment of the hemodynamic effect of prazosin and hydralazine in patients with severe chronic congestive heart failure.

Aged↗
PubMed1981

A closed chest animal model for the study of reversible ischemia.

An experimental methodology consisting of partial coronary occlusions, pacing-induced myocardial ischemia and photokymography-aided fluoroscopic study of segmental left ventricular motion, was verified in 14 closed chest dogs. A partial intracoronary occluder device was found suitable for single or multiple coronary arterial stenosis, and remained patent up to 10 h with 10/cm3 heparin administration. With 38% proximal left circumflex coronary artery stenosis, pacing up to 220 beats/min produced no significant regional or global left ventricular dysfunction. In contrast, a 68.5% stenosis which was not associated with dysfunction in the resting state produced significant derangements of segmental motions at a pacing rate of 150 beats/min. Photokymography probes placed at several segments of the left ventricular epicardial and endocardial interface delineated by fluoroscopy or ventriculography allowed monitoring of regional contractions in both pacing-induced ischemic and remote nonischemic zones. The methodology is considered ready for further applications in experimental studies of ischemic states and treatments, simulating clinically meaningful coronary stenosis in the animal without requiring prior thoracotomy and pericardiotomy for implanting occluders.

Animals↗
PubMed1980

Analysis of cardiac kinetics: use of a new photo-optic technique.

The photokymograph (PKG) is a new noninvasive instrument that can record segmental myocardial wall motion from self-illuminated images such as are produce; by fluoroscopy, cine ventriculography, two-dimensional sonography, and 99mTc scintigraphy. The PKG can be calibrated to provide amplitude of myocardial tissue motion. The recordings of segmental wall motion obtained closely resemble those recorded by established techniques, both during control state and during ischemic episodes. Regression analysis was performed to compare PKG recordings with frame by frame analysis of left ventriculograms (0.98) and with M-mode echo derived from two-dimensional images (r = 0.97). The PKG has some distinct advantages over existing techniques used to analyze segmental wall motion: it is inexpensive, usable simultaneously over multiple areas, analyzes individual beats, and is not restricted to any particular myocardial wall or any particular angle of motion.

Echocardiography↗
PubMed1980

Pericardial involvement in asymptomatic patients undergoing long-term hemodialysis: an echocardiographic study.

M-mode echocardiography was performed in 20 asymptomatic patients undergoing chronic hemodialysis, in order to assess pericardial involvement. Six of the patients had small to moderate amounts of pericardial effusion. One of these patients and 5 others showed an echocardiographic pattern of pericardial thickening. No correlation was found between pericardial involvement and age, sex, secondary hyperthyroidism, serum levels of urea, creatinine or uric acid. The traditional diagnostic techniques commonly used for the detection of pericardial disease such as physical examination, chest X-ray and electrocardiography were not helpful in our patients. Our study demonstrates the high incidence of pericardial involvement in asymptomatic chronically dialyzed patients. Periodic echocardiographic evaluation is recommended for assessment of the presence and significance of these findings.

Adolescent↗
PubMed1979

Echocardiographic findings in cardiogenic shock due to right ventricular myocardial infarction.

The echocardiographic findings in a patient with cardiogenic shock secondary to acute right ventricular myocardial infarction based on typical clinical, electrocardiographic, and hemodynamic features are described. The echocardiogram demonstrated a large RV/LV minor axis ratio caused by a volume overload of the right ventricle and an underfilled left ventricle. The interventricular septum showed abnormal movement, presumably due to right ventricular overload or severe disease of the left anterior descending coronary artery. Diminished septal systolic thickening, as seen in our patient, may be explained by extension of the infarct from the right ventricle to the adjacent part of the septum. Predominant right ventricular involvement can be a cause for a correctable hypotension in patients with acute myocardial infarction and should therefore be recognized early. The echocardiographic picture demonstrated in our patient, when considered in conjunction with the clinical status, can be useful for early diagnosis.

Echocardiography↗