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A patient with muscular subaortic stenosis underwent hemodynamic studies on four separate occasions. At cardiac catheterization, there was a peak systolic gradient of 10 to 20 mm. Hg between the left ventricle and the brachial artery. The effective orifice size was 2 to 4 square centimeters. This gradient increased to 95 mm. Hg when isoproterenol was infused. During the strain of the Valsalva maneuver a gradient of 95 mm. Hg was induced; this regressed rapidly upon release of straining. Concomitantly, the cardiac output decreased by 61 per cent, and the stroke volume by 69 per cent of resting values. The calculated orifice size was 0.2 square centimeter. When simultaneous left ventricular and brachial arterial pressures were measured in a patient with left ventricular hypertrophy due to hypertension, and in a normotensive patient, no pressure gradient developed between the left ventricle and aorta during the Valsalva maneuver. All the drugs or maneuvers associated with an increase in left ventricular obstruction in muscular subaortic stenosis, including the Valsalva maneuver, have in common a decrease in cardiac size or in end-systolic volume. These findings lend support to the view that, with more complete left ventricular emptying, a greater opportunity is afforded for approximation of the already narrowed ventricular outflow tract, with resultant obstruction in late systole.

A young woman abruptly developed the return of angina pectoris after a successful coronary bypass graft. Angiography and repeated surgery revealed a proximal occlusion of the vein graft, not related to poor distal run-off. Pathologic examination of the removed vein graft revealed thrombotic occlusion associated with an intimal mycotic abscess.

Eighteen subjects with a short P-R interval (

A multistage, continuous treadmill exercise test was designed to achieve nearmaximal heart rates without concomitant exhaustion. A series of 362 ambulatory, asymptomatic Caucasian men with mean age of 44 years, who were predominantly sedentary government administrators, were tested with this protocol for ischemic S-T-segment responses. All subjects reached 90 to 99 per cent predicted maximal heart rate. With continuous monitoring of a bipolar lead, 3 subjects had downsloping S-T-segments with at least a 1 mm. J-junctional depression during exercise; 2 others had “positive” and 8 others equivocal changes after exercise. Eight subjects had frequent premature ventricular contractions, but there were no serious tachyarrhythmias. There were no instances of hypotension, syncope, or untoward vagal reactions. Three subjects requested test termination because of fatigue; none complained of dyspnea. Because of the high degree of subjective acceptability and apparent safety of this protocol, further application and investigation of this approach is suggested for screening high-risk populations by referral centers.

A capacitance displacement transducer with a linear response and constant sensitivity for a frequency range of 0-1000 Hz is described. Its application to measurement of chest wall motions was verified using static displacements from flat and curved surfaces and both human tissue and metal. The transducer has been used to obtain recordings of apex motion, heard sounds, and brachial and radial pulses. Its advantages are that it is noncontacting and linear, and that it has a wide frequency response and can easily be calibrated to obtain quantitative data of actual motion. Problems encountered in use were the mechanical positioning of the probe including respiratory motions in the measurement and the need to insulate the probe with a film of thin plastic to insure against an electrical hazard to the subject.