Circulation
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To study the effect of respiration and negative intrathoracic pressure on the left ventricular outflow tract gradient in patients with muscular subaortic stenosis, we studied nine patients using various respiratory maneuvers at the time of cardiac catheterization. Deep inspiration decreased the left ventricular outflow tract gradient from 60 +/- 11 to 34 +/- 6 mm Hg (p less than 0.01) and decreased the left ventricular ejection time (corrected for heart rate) from 0.42 +/- 0.01 to 0.38 +/- 0.01 second (p less than 0.001). The Müller maneuver decreased the left ventricular outflow tract gradient from 69 +/- 13 to 7 +/- 3 mm Hg (p less than 0.001) and decreased the corrected left ventricular ejection time from 0.42 +/- 0.02 to 0.24 +/- 0.01 second (p less than 0.01). ⋯ These findings indicate that negative intrathoracic pressure reduced the left ventricular outflow tract gradient in muscular subaortic stenosis. We believe that negative intrathoracic pressure produced these changes by increasing left ventricular afterload through an increase in left ventricular transmural pressure, resulting in a decrease in the left ventricular outflow tract obstruction. These observations provide an explanation for the decrease in pressure gradient that occurs on inspiration in patients with muscular subaortic stenosis.
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Although mitral valve prolapse is often associated with a systolic click or murmur, it is not widely appreciated that a sound or murmur may also occur in diastole. Nine patients with a systolic click or murmur and echocardiographic evidence of mitral prolapse had, in addition, a diastolic sound or an early diastolic murmur best heard at the apex or left sternal border. The sound, which was of high frequency and easily audible, followed A2 by 70-110 msec (mean 94 +/- 5 msec), and coincided with the point where the prolapsed posterior leaflet returned from the left atrium and recoapted with the anterior mitral leaflet. ⋯ The diastolic murmur, also of high frequency, was brief and decrescendo, and simulated aortic regurgitation in two patients. Thus, mitral prolapse may be associated with a sound or murmur in diastole. When a diastolic sound or murmur is best heard apically, even if accompanied by a systolic murmur, mitral valve prolapse should be considered.
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Three young children with anomalous origin of the left coronary artery (LCA) from the pulmonary artery were studied by two-dimensional echocardiography. The LCA was shown to be in confluence with the left posterior aspect of th pulmonary artery root in the two patients studied preoperatively. ⋯ In all, the LCA could be followed beyond the branching point. This study demonstrates the feasibility of noninvasive diagnosis of anomalous origin of the LCA from the pulmonary artery by direct visualization with two-dimensional echocardiography.
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Medical control for paramedics by means of radio and ECG telemetry is costly, time consuming, and of unproved value. We assessed the interaction between emergency room physicians and paramedics during ambulance transport of "seriously ill" cardiac patients (cardiac arrest, acute myocardial infarction, or new onset of crescendo angina pectoris) with paramedics in service. Thirty-five percent of all arrhythmias and 35% of potentially life-threatening arrhythmias were misclassified. ⋯ Mortality reflected correct diagnosis and treatment. In-hospital and overall mortalities were 12% and 33%, respectively, for patients who were correctly diagnosed and treated (p < 0.06), compared with 20% and 43%, respectively, for patients who were incorrectly diagnosed or incorrectly treated (p < 0.04). More rigorous medical control is needed to improve the quality of patient care and outcome and to further integrate the advanced life support program into the health care system.