Sympathetic responsiveness and plasma norepinephrine during therapy of chronic congestive heart failure with captopril

The interaction of cardiac function and sympathetic tone in severe chronic heart failure was evaluated in 24 patients by assessing the cardiac index/plasma norepinephrine relationship. Potential changes were assessed during first-dose and long-term captopril therapy including sympathetic responsiveness to the gravitational stress of head-up tilt. Baseline cardiac index and norepinephrine levels demonstrated a significant inverse correlation (r = ?0.640, p < 0.001). Norepinephrine decreased from 803 ± 116 to 635 ± 76 pg/ml following first-dose captopril therapy (p < 0.02), with overall hemodynamic improvement. However significant first-dose correlations were not observed. During long-term therapy, norepinephrine decreased from 694 ± 118 to 457 ± 106 pg/ml, associated with improvement of symptoms and exercise tolerance. The extent of cardiac index increase was matched by norepinephrine reduction, so that their correlation was maintained (r = ?0.540, p < 0.02). First-dose and long-term therapy were associated with improved responsiveness of sympathetic tone to the reduction of cardiac index induced by the gravitational stress of tilt. In summary, sympathetic tone was increased in severe heart failure, correlating inversely with cardiac function. Although there was improvement of cardiac function with first-dose captopril therapy, significant correlations of supine improvement with reduction of sympathetic tone were noted primarily with long-term therapy. Responsiveness of sympathetic tone to the stress of tilt however, was evident during first-dose and long-term therapy.     

Laser coronary angioplasty: experience with 9 cadaver hearts

Experience with laser angioplasty in 16 coronary arteries in 9 cadaver hearts is presented. Coronary obstructions were due to experimentally created thrombi as well as to naturally occurring calcified plaques. Successful laser angioplasty was achieved in 14 of 15 arteries. One artery was sacrificed to etermine factors necessary for deliberate perforation of the arterial wall. This procedure required more than 30 seconds of laser energy at 3.0 W with the catheter tip almost perpendicular to the wall. Penetration of the arterial wall occurred only in the second left anterior descending artery which was plaque-occluded because of operator inexperience.     

Exercise versus cold temperature stimulation during radionuclide cineangiography: Diagnostic accuracy in coronary artery disease

To assess the relative efficacy of cold temperature stimulation and bicycle exercise in inducing ischemia detectable by radionuclide Cineangiography, we used both stresses to study 20 normal subjects and 54 patients with coronary artery disease (CAD), 42 of whom had not had myocardial infarction. Cold stimulation caused increases in heart rate and arterial pressure which were significantly less marked than those caused by exercise. Regional left ventricular dysfunction was induced by cold in 24 of 41 patients without previous infarction (57%) and by exercise in 34 of 42 patients (81%) (p < 0.05), but was absent in all normal subjects during either stress. Left ventricular ejection fraction increased during exercise in all normal subjects (average increase 18%) but decreased during cold stimulation in 12 of 20 subjects. Because of the disparate response of normal subjects to the 2 stresses, the sensitivity and specificity of radionuclide Cinean-giography were assessed over a wide range of ejection fraction changes independently for each stress. During exercise, at ejection fraction changes in which specificity was high, sensitivity also was high, but during cold stress, specificity was relatively poor at ejection fraction changes in which sensitivity was high, and sensitivity was relatively poor when specificity was high. During exercise, patients with anatomically severe (3-vessel, left main, proximal left anterior descending) disease manifested significantly greater reduction in ejection fraction than did patients with less severe stenoses (?10% versus ?3%, p < 0.001); cold stimulation did not lead to similar separation (?2% versus ?3%, difference was not significant). Therefore, when radionuclide Cineangiography is performed, exercise is more effective than cold stress in separating normal subjects from patients with fixed obstructive CAD and in identifying patients with anatomically severe CAD.     

Functional importance of coronary collateral vessels

Angiographically demonstrable coronary collateral vessels are believed to preserve myocardial function at rest, but disagreement exists regarding the importance of collaterals in mitigating exercise-induced ischemic dysfunction. Therefore, we used radionuclide cineangiography during exercise to assess the left ventricular (LV) functional effects of collateral vessels in 125 patients with at least 1 major coronary artery that had greater than or equal to 90% diameter stenosis but without prior myocardial infarction. Regional LV function, graded on a 4-point scale, worsened during exercise by at least 1 grade in 14 of 43 regions (33%) with good collaterals, and in 70 of 98 without good collaterals (p less than 0.001). Of the 43 good collaterals, 14 were supplied by arteries with greater than or equal to 75% stenoses; 10 of 14 regions (71%) thus supplied worsened by at least 1 grade (p less than 0.01). The ischemia-mitigating effect of coronary collateral vessels also affected the magnitude of exercise-induced global dysfunction. Of 43 patients with only one greater than or equal to 90% stenotic artery, 18 had good collaterals; in these patients, average LV ejection fraction (EF) at rest was 51 +/- 8%; LVEF during exercise was 46 +/- 7%. In the 25 patients without good collaterals, LVEF at rest was 52 +/- 7%, and LVEF during exercise was 41 +/- 9% (p less than 0.005 vs good collaterals).(ABSTRACT TRUNCATED AT 250 WORDS)     

Transluminal laser catheter angioplasty

The first transluminal laser angioplasty in animals is reported herein. An Argon laser and a specialized coronary arterial catheter with a fiberoptic wave guide were used. Immediate histologic changes consisted of a moderate degree of intimai necrosis and some loss of elastic tissue. At 5 days the intima was repaired, but focal elastic tissue loss persisted.     

Duration of ejection in aortic stenosis: effect of stroke volume and pressure gradient

The theoretical effect of variable ventricular function on left ventricular ejection time in aortic stenosis was predicted by applying data measured in 52 patients with pure aortic stenosis to equations derived from the relations of Gorlin and Gorlin and Weissler et al. Ejection time and aortic valve area are not, of necessity, linearly related because (Formula: see text) where LVET is left ventricular ejection time, k is a constant, SV is stroke volume, PG is mean aortic pressure gradient and AVA is aortic valve area. When the patients were separated into performance groups on the basis of cardiac index (at 2.8 liters/min per m2), the linear regression relating the measured SV/square root PG with valve area in 18 patients with normal function (SV/square root PG = 11.1 AVA + 2.0, r = 0.969, p less than 0.001) predicted ejection time prolongation with decreasing valve area. In 34 patients with poor function, however, the decrease in SV/square root PG with decreasing valve area was more marked (SV/square root PG = 12.6 AVA + 0.4, r = 0.894, p less than 0.001), predicting a shorter ejection time at any given valve area in this group. As predicted by the effect of valve area on the equation, ejection time becomes most variable at a small aortic valve area. Independent ejection time measurement in these patients validated the predicted effect.