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Biomedical subjects

M A Quinones

Publications and source records attributed to M A Quinones.

103 records · Page 6Linked to original sources
PubMed1975

His bundle electrograms in patients with congestive cardiomyopathy.

His bundle electrograms were obtained at rest and during atrial pacing in 16 patients with congestive cardiomyopathy. Increments in heart rate during atrial pacing were associated with progressive increases in the A-H interval in all patients. Three patients had abnormal conduction (prolonged P-H) proximal to the His bundle; atrial pacing resulted in second degree A-V block (A-H block) in these three patients at paced rates below 130/min; these three patients were on digitalis at the time of the study. Two patients ahd left bundle branch block associated with a prolonged H-V interval suggesting a conduction disturbance in the contralateral bundle system either at or distal to the branching portion of the His bundle. Two patients had H-V prolongation in the presence of a normal QRS duration which suggests delay in the bundle of His. Two patients with normal H-V intervals had marked prolongation of the total intraventricular conduction time (H-S prolongation). The His bundle electrogram uncovered abnormalities in atrioventricular conduction not apparent on the standard electrocardiogram and has allowed expansion of our knowledge regarding the electrophysiologic features of congestive cardiomyopathy.

Adult↗
PubMedDate not supplied

Doppler echocardiography: application to the assessment of successful thrombolysis of prosthetic valve thrombosis.

Prosthetic valve thrombosis remains a significant problem despite anticoagulation therapy and advances in valve design. Thrombolytic therapy offers an alternative approach to valve replacement in patients with high surgical risk. In this article we discuss three cases in which Doppler echocardiography was used to confirm the diagnosis of prosthetic mitral valve obstruction and serially monitor the response of valvular hemodynamic measurements to thrombolysis with intravenous streptokinase. These cases illustrate how the Doppler technique, in addition to allowing the noninvasive diagnosis of prosthetic valve obstruction, is presently the ideal tool to follow serially the effect of thrombolytic therapy on prosthetic valve function.

Aged↗
PubMedDate not supplied

Determination of the time course of left ventricular wall stress and velocity of fiber shortening in man by simultaneous left ventricular pressure and echocardiographic recording: preliminary report.

This report presents a method for determining the time course of circumferential LV wall stress and fiber shortening velocity (endocardial as well as midwall) using simultaneous recordings of LV dimensions by echography and LV pressure (micromanometer). The values for max VCF, VCF at peak stress, mean VCF, and peak stress are in general agreement with those observed with previous methods; the separation between normal and abnormal LV function appears to be good. The method permits frequent observations to be performed in a single patient, which is of particular value during acute interventions. Data from a small number of interventions suggest that VCF in man is relatively insensitive to acute changes in preload, is inversely affected by changes in afterload and appears sensitive to inotropic stimulation. Although VCF seems to be a good index of LV performance, its sensitivity to afterload might, at times, limit its usefulness.

Blood Flow Velocity↗
PubMedDate not supplied

Evolution of hemodynamics after orthotopic heart and heart-lung transplantation: early restrictive patterns persisting in occult fashion.

Though successfully transplanted hearts respond in such a way that individuals remain remarkably asymptomatic, they do not function normally. Characterization of early hemodynamic patterns and their evolvement has not been done. The evolution of hemodynamic indices in 20 patients receiving orthotopic heart (n = 17) or combined heart-lung (n = 3) transplants is therefore documented. In 15 isolated heart recipients, right heart catheterization was performed at 24 to 48 hours, 1 to 2 weeks, 4 to 8 weeks, and greater than 3 months after surgery at the time of routine endomyocardial biopsy. Early, patients had elevated mean blood pressure (96 +/- 14 mm Hg, mean +/- standard deviation), mean right atrial pressure (15 +/- 6 mm Hg), right ventricular end-diastolic pressure (16 +/- 7 mm Hg), mean pulmonary artery pressure (30 +/- 7 mm Hg), and mean pulmonary capillary wedge pressure (19 +/- 6 mm Hg), but normal resting heart rate (96 +/- 14 beats/min) and cardiac output (5.6 +/- 1.6 L/min). Heart rate, blood pressure, and output did not change during follow-up, but right atrial pressure decreased dramatically (4 +/- 2 mm Hg at 3 months), as did right ventricular end-diastolic pressure (4 +/- 4 mm Hg), mean pulmonary artery pressure (21 +/- 8 mm Hg), and pulmonary capillary wedge pressure (11 +/- 4 mm Hg). Analysis of right heart filling dynamics revealed an abnormal inspiratory rise in mean right atrial pressure (15 +/- 6 and 27 +/- 7 mm Hg at 24 to 48 hours) that subsequently resolved. In eight patients whose resting follow-up right heart pressures normalized, rapid volume challenge uncovered occult restrictive right atrial pressure patterns that increased from 4 +/- 4 to 9 +/- 4 mm Hg after infusion of saline solution. Kussmaul's response was not apparent with prevolume infusion, but volume expansion caused appearance of this hemodynamic pattern. All patients had early evidence of tricuspid insufficiency, but in two patients, the Doppler regurgitant fraction was over 50%. These two individuals had hemodynamics similar to the other 15 patients initially, but in contrast, their right heart filling pressures did not change during follow-up. Other significant echocardiographic findings included enlarged atria and increased left ventricular mass in all patients. In two of three combined heart-lung transplant patients, similar hemodynamic patterns were evident. Rejection indices did not correlate with hemodynamic observations. Thus a characteristic evolvement of hemodynamics in heart and heart-lung transplants that mimic dynamics associated with restrictive myocardial disease is documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗