PubMed Health⌕ Search

Biomedical subjects

D F Leon

Publications and source records attributed to D F Leon.

At least 19 recordsLinked to original sources
PubMed1986

Extent of mitral calcific deposits determined by cineangiography in mitral stenosis and their effect on valve motion, hemodynamics and clinical signs.

The relation between the degree of leaflet calcium in a stenotic mitral valve and several parameters of valve mobility, hemodynamics and clinical signs was determined in 105 patients with relatively pure mitral stenosis (MS). The amount of mitral valve calcific deposits was determined by grading cineangiograms. Compared to 71 patients with no or minimal valvular calcium, the 23 patients with heavy valve leaflet calcium were significantly older, more likely to be men and more likely to be in atrial fibrillation. These patients also had a significant reduction of valve mobility in that their M-mode measurements of valve excursion and rate of valve opening were significantly reduced compared to those of patients without heavy valvular calcium. Two-dimensional echocardiograms also documented a significant reduction in valve mobility and progressive restriction in doming of the anterior mitral leaflet as the level of calcium increased. The prevalence of an opening snap was significantly decreased in patients with heavy vs no or light valvular calcium, and patients without an opening snap had reduced valve mobility. However, a considerable number of patients with moderate to heavy valve calcium retained an opening snap.

Adult↗
PubMed1986

Venous systolic thrill and murmur in the neck: a consequence of severe tricuspid insufficiency.

A palpable venous systolic thrill and murmur at the base of the neck are described as new physical findings in five patients with severe tricuspid regurgitation. In two of these patients, the tricuspid valve had been resected as treatment for infective endocarditis related to intravenous drug abuse. The third patient had severe chronic pulmonary disease with right heart failure. The fourth patient had a complex congenital defect in which the mitral valve served as the venous atrioventricular valve and was severely incompetent. The fifth patient suffered from long-standing rheumatic mitral and tricuspid disease with pulmonary hypertension 10 years after placement of a mitral prosthesis. From these observations, it is apparent that pulsatile retrograde flow in the cervical veins resulting from severe right-sided atrioventricular valve incompetence can produce a palpable systolic thrill and murmur at the base of the neck.

Adolescent↗
PubMed1977

Pulmonary hypertension in the CREST syndrome variant of progressive systemic sclerosis (scleroderma).

Severe pulmonary hypertension without pulmonary fibrosis occurred in 10 patients with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, telangiectasia), reputedly a benign variant of progressive systemic sclerosis. Time from the initial symptom, Raynaud's phenomenon, to the recognition of pulmonary hypertension was as long as 40 years. Pulmonary hypertension and increased pulmonary vascular resistance was shown in all patients. Autopsy examination in three of six deaths attributable to pulmonary hypertension showed intimal proliferation with myxomatous change in the small- and medium-sized pulmonary arteries similar to changes in the digital arteries of patients with scleroderma and Raynaud's phenomenon, and interlobular renal arteries of those with "scleroderma kidney." It is concluded that the CREST syndrome is not entirely benign but may be complicated, after a long clinical course, by progressive pulmonary vascular obliteration, pulmonary hypertension, and death in the absence of significant pulmonary fibrosis.

Adult↗
PubMed1976

Sound pressure correlates of the Austin Flint murmur. An intracardiac sound study.

Mitral valve motion and pressure correlates of the Austin Flint murmur (AFM) were investigated in nine patients with aortic regurgitation using high fidelity catheter tip micromanometers and the mitral valve echocardiogram (MVE). External phonocardiography demonstrated a mid-diastolic murmur (MDM) in eight subjects and a presystolic murmur (PSM) in five. Maximum intensity of both AFM components was found in the left ventricular (LV) inflow tract; the murmur was not recordable in the left atrium (LA). In two patients, an apparent AFM was recorded in the intracardiac phonocardiogram when absent externally. Only one subject had a significant late diastolic "reversed" or LV to LA gradient; in this patient, presystolic mitral regurgitation was shown angiographically but no PSM was present and MVE revealed absence of atriogenic mitral valve re-opening. In two subjects, a PSM disappeared from the external phono when a "reversed" gradient occurred during the diastolic pause following a ventricular premature systole; this LV to LA gradient was associated with diastolic mitral regurgitation recordable in the left atrial phono. In two patients, LV inflow phono showed the MDM to begin 80-120 msec after the aortic second sound and during the D to E phase of the MVE. The rate of early diastolic mitral valve closure in patients (152 +/- 24 mm/sec) was not significantly different from 13 normals (232 +/- 10 mm/sec). With regard to the genesis of the AFM, the present study concludes: 1) diastolic mitral regurgitation plays no role, and 2) antegrade mitral valve flow is required but simultaneous retrograde aortic flow may also be necessary.

Aortic Valve Insufficiency↗
PubMed1976

Determinants of variation between Fick and indicator dilution estimates of cardiac output during diagnostic catheterization. Fick vs. dye cardiac outputs.

Simultaneous Fick and duplicate dye cardiac outputs were done in 105 patients with various cardiovascular diseases during routine cardiac catheterization. Dye was injected into the pulmonary artery and sampled from the brachial artery. Nineteen patients had mitral and/or aortic valvular regurgitation. Eighty-four per cent of the duplicate dye cardiac outputs agreed within 10 per cent variation from the line of identity, and 98 per cent were within 25 per cent. There was no systematic difference between the Fick and dye methods. Seventy-five per cent agree within 20 per cent variation from the line of identity. However, individual variation ranged from -27 to +58 per cent. There was, also, no systematic difference between Fick and dye methods either with low cardiac index or valvular regurgitation. Variation between the two methods was less with low cardiac index and greater with higher cardiac index. The variation was not increased in the presence of valvular regurgitation. The variation in the two methods could partly be explained by errors in the measurement of arteriovenous oxygen difference and oxygen consumption. When the injection is made into the pulmonary artery and sampled from the brachial artery, dye outputs are valid irrespective of the level of resting cardiac index and valvular regurgitation as long as there are enough points to draw a straight line from semilogarithmic trace of the descending limb.

Cardiac Catheterization↗
PubMed1975

Reversibility of left ventricular asynergy by nitroglycerin in coronary artery disease.

To evaluate the potential reversibility of left ventricular asynergy in patients with coronary artery disease, pre- and postnitroglycerin left ventriculography was performed in 32 subjects. In four other subjects left ventriculography was repeated without intervention of nitroglycerin. Changes in ejection fraction and percentage of systolic shortening of three minor axes from the first to the second angiogram were then calculated. Changes were not significant for the myocardial infarction group or for the control group without the intervention of nitroglycerin. Normal left ventricles showed small but significant changes (p less than 0.05). Patients with coronary artery disease but without previous myocardial infarction who demonstrated asynergy in their first angiogram showed three types of response: (1) no significant change (p less than 0.05)-irreversible asynergy; (2) significant change (p less than 0.025) with residual dysfunction-partially reversible asynergy; (3) significant change (p less than 0.001) without residual dysfunction-completely reversible asynergy. It is concluded that postnitroglycerin ventriculography is useful in assessing the reversibility of left ventricular asynergy in patients with coronary artery disease.

Adult↗
PubMed1974

Autonomic mechanisms in hemodynamic responses to isometric exercise.

Selective autonomic blockade with intravenous propranolol, practolol, atropine, and combined atropine-propranolol was utilized to elucidate the role of the autonomic nervous system in the hemodynamic responses in young adult male volunteers to handgrip sustained at 30% of maximal voluntary contraction for 3 min. The initial 30 s of the tachycardia response was found to be mediated by withdrawal of vagal dominance, as evidenced by blockade of this response by prior atropinization. The mid and late portion of the heart rate response curve was demonstrated to be sympathetic in origin, since it was unaffected by atropine, but was suppressed by combined atropine-propranolol blockade. Sympathetic stimulation appears to be a secondary mechanism for increasing the heart rate, however, as it becomes operative only after the first mechanism of vagal withdrawal has been utilized. This was confirmed by the finding that beta adrenergic receptor blockade alone had little effect on the heart rate response curve. The pressor response to handgrip was accompanied by increased cardiac output and no change in calculated systemic vascular resistance. After propranolol, handgrip resulted in increased peripheral resistance and an equivalent rise in arterial pressure, but no increase in cardiac output. It was concluded that the increase in resistance was the result of sympathetically induced vasoconstriction. This response was shown to be independent of peripheral beta adrenergic receptor blockade by the use of practolol, a cardio-selective beta adrenergic receptor-blocking drug which caused identical hemodynamic responses to those observed after propranolol. Left ventricular ejection time (corrected for heart rate) was prolonged by handgrip. The increased afterload imposed on the left ventricle by sustained handgrip may explain the prolongation of ejection time index. Preejection period was prolonged by SHG after propranolol and shortened after atropine. In addition to confirming the previously defined role of the parasympathetic nervous system, this study delineates the role of the sympathetic nervous system in the heart rate and pressor responses to sustained handgrip.

Adult↗