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Biomedical subjects

A M Weissler

Publications and source records attributed to A M Weissler.

At least 55 records · Page 3Linked to original sources

Left ventricular performance in mitral regurgitation assessed with systolic time intervals and echocardiography.

Among 22 patients with isolated mitral regurgitation of various origins, systolic time intervals (preejection period [PEP] index, left ventricular ejection time [LVET] index and PEP/LVET) and echocardiographic measures of left ventricular performance (end-diastolic diameter [Dd], end-systolic diameter [Ds], and the percent change in minor axis diameter [% delta D]) were calculated. The patients were classified into two groups, those with a normal or supernormal % delta D (group I, 15 patients) and those with a decreased % delta D (group II, 7 patients). On group analysis, prolongation of the preejection period, shortening of the left ventricular ejection time and an increase in PEP/LVET was generally characteristic of patients with mitral regurgitation. These changes were accentuated when mitral regurgitation was complicated by echocardiographic evidence of diminished left ventricular contractile performance (% delta D less than 30 percent). An increase in PEP/LVET to greater than 0.05 was consistently associated with abnormal left ventricular performance, whereas a normal PEP/LVET ratio reflected normal or supernormal left ventricular performance. An inverse linear relation was found between PEP/LVET and % delta D. When compared with previous data on the relation of these variables among patients without valve insufficiency, PEP/LVET proved to be increased for any level of % delta D in mitral regurgitation. The state of digitalization did not appear to influence the relation between PEP/LVET and % delta D. The use of echocardiographic measurements augments the determination of systolic time intervals in the analysis of left ventricular performance in patients with mitral regurgitation.

Adolescent↗

Left ventricular performance in coronary artery disease by systolic time intervals and echocardiography.

Determinations of systolic time intervals and echocardiographic measures of left ventricular performance were made in twenty-five normal subjects and 37 patients who had convalesced from a previous transmural myocardial infarction. On group analysis the patients with previous myocardial infarction demonstrated significant differences from the normals in each of the noninvasive measures. Among the noninvasive measures the PEP/LVET and deltaD% proved to be the most sensitive indicators of left ventricular dysfunction. Deviations from the normal range in PEP/LVET and deltaD% occurred in 65% to 70% of patients asymptomatic for dyspnea and fatigability (20 patients) and in 85% of patients asymptomatic for angina pectoris (13 patients). Neither the presence of phonocardiographically documented S3 or S4 or the finding of an abnormal C/T ratio on standard chest x-ray reliably detected patients with abnormal left ventricular performance. Among 26 patients studied by coronary arteriography, abnormal left ventricular performance by PEP/LVET and deltaD% occurred in less than 30% of those with obstruction (70% or greater) of one coronary artery and in over 80% of those with obstruction of two or three major arteries. A close correlation existed between the level of left ventricular performance measured by the PEP/LVET and the deltaD% (r = 0.93). These studies document the high degree of sensitivity of the noninvasive measures and demonstrate their superiority over clinical methods for detecting abnormal left ventricular performance in patients with previous myocardial infarction.

Echocardiography↗

New observations on the effects of atropine on the sinoatrial and atrioventricular nodes in man.

Previous observations of slowing of the heart rate after administration of atropine in doses smaller than 0.4 mg and recent reports of development of rhythm disorders in patients with acute myocardial infarction given atropine prompted us to evaluate systematically the effects of various doses of atropine (0.1 to 0.8 mg) on the response of the sinoatrial (S-A) and atrioventricular (A-V) nodes in healthy volunteers. The response of the S-A node to atropine was characteristically bimodal, slowing at smaller doses and accelerating at larger doses. In contrast, the A-V node showed acceleration of conduction in response to all doses of atropine used. A hypothesis based on current understanding of the electrophysiologic parameters governing impulse formation and impulse conduction is advanced to explain the apparent paradox in the S-A and A-V nodal responses to small doses of atropine. The results suggest the need for caution and continuous rhythm monitoring when giving atropine to patients with acute myocardial infarction.

Adult↗