Comparative effects of transdermal clonidine and oral atenolol on acute exercise performance and response to aerobic conditioning in subjects with hypertension.

We compared the effects of transdermal clonidine and oral atenolol on acute exercise performance and on conditioning response to an 8-week program of regular aerobic exercise in young, otherwise healthy subjects with mild hypertension. The study was a double-blind, randomized, parallel-group study with placebo control. Twenty-seven subjects (11 receiving transdermal clonidine, 8 receiving oral atenolol, and 8 receiving placebo) completed the study. Atenolol controlled blood pressure in all 8 subjects, vs 6 of 11 in the transdermal clonidine group and 0 of 8 in the placebo group. Both active drugs lowered systolic blood pressure during exercise. With clonidine treatment, the antihypertensive effect during exercise was smaller and was observed only at low and moderate workloads. Acute exercise performance (subjects receiving drug but still unconditioned) was assessed by endurance time at a constant workload equal to the highest workload completed on a previous 2-minute incremental exercise test. Endurance time was reduced 35% by atenolol but not by transdermal clonidine or placebo. Neither active drug interfered with the progress of the conditioning program, as measured by gradual lengthening of exercise time. However, as assessed by change in oxygen uptake standardized to a heart rate of 170 beats per minute, the improvement in conditioning was twice as great in subjects receiving transdermal clonidine and placebo (+20%, +18%) as it was in those receiving atenolol (+8%). Subjects receiving placebo and transdermal clonidine lost weight; subjects receiving oral atenolol gained weight. The changes in weight were small.

The effect of phenylpropanolamine on blood pressure during upright bicycle exercise in normal subjects.

We studied the effect of a single oral dose (37.5 mg immediate release) of phenylpropanolamine (PPA) in six normal subjects during upright incremental bicycle exercise to symptom tolerance. The study was double blind and placebo controlled with a crossover design. The patients rested supine for 90 minutes after dosing, sat quietly on the bicycle for five minutes, and then began exercise. After PPA systolic blood pressure was increased during supine rest (135 +/- 14 mmHg vs 120 +/- 10 mmHg for placebo; P less than 0.01) and while sitting on the bicycle prior to exercise (131 +/- 8 mmHg vs 121 +/- 8 mmHg for placebo; P less than 0.05). However, PPA did not alter the expected increase in systolic blood pressure with progressive exercise. Systolic blood pressure at maximum exercise (254 +/- 43 watts) was 185 +/- 14 mmHg for PPA vs 182 +/- 13 mmHg for placebo (difference not significant). This suggests that the physiological factors controlling blood pressure during exercise (increased cardiac output, vasodilation of vessels in exercising muscles and vasoconstriction of non-exercising vascular beds) are not altered significantly by a dose of PPA sufficient to increase resting systolic blood pressure, at least in normal subjects.

Coronary artery bypass surgery in patients on maintenance dialysis: long-term survival.

Coronary artery bypass grafting (CABG) can be performed with acceptable risk and results in symptomatic improvement in patients with end-stage renal disease (ESRD). However, the effect of CABG on long-term survival in these patients is unknown. We retrospectively identified 39 patients (group 1) with ESRD who underwent CABG for intractable angina between January 1975 and February 1987 while on maintenance dialysis. Thirty-nine dialysis patients (group 2) were also retrospectively selected for comparison and matched for age, sex, year of initiation, length of time on dialysis, and presence of diabetes mellitus and atherosclerotic heart disease at initiation of dialysis. Using life-table analysis, survival probability (with 95% confidence limits) was determined from the time of CABG for group 1 or after an equivalent period of time on dialysis for group 2. Two life-table analyses were performed; one with study end-points of death, withdrawal (renal transplantation, transfer to other dialysis facilities, and reoperation), and alive on dialysis; and a second with identical end points except that noncardiac deaths were treated as withdrawals. Coronary arteriography revealed severe three vessel disease, left ventricular dysfunction, and segmental wall motion abnormalities in most patients. A mean (+/- SD) of 2.56 +/- 0.75 vessels were bypassed with an operative mortality (30 days) of 2.6%. Mean follow-up after CABG in group 1 was 34.9 +/- 30.1 months, and in most patients functional classification improved. Mean follow-up for group 2 was 17.2 +/- 15.2 months. Two-year survival was 91.7% in group 1 and 51.4% in group 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Psychological, social, and somatic prognostic indicators in old patients undergoing long-term dialysis.

We prospectively studied the influence of 29 demographic, social, psychological, and somatic factors on survival of 78 patients over age 70 years receiving long-term dialysis. Three years after the prospective evaluation, 54% of the patients had died. Only four factors, all psychosocial, were prognostically important. The patients who survived rated higher on the Karnofsky scale (85 vs 78 points), gained less weight between dialyses (1.5 vs 1.9 kg), more often underwent home dialysis (44% vs 21%), and less often wished for transplantation (28% vs 57%). In stepwise and multiple regression analysis, home dialysis and Karnofsky scale resulted in best fit. No somatic variable predicted outcome. Thirty-one patients were reinterviewed three years later. At that time, more patients were depressed and had a lower income, fewer wanted a transplant, and five had lost their living companion. There was a decrease in the number of patients who cooked their own meals, spent time outdoors, went to church, or had hobbies. Activity on the Karnofsky scale decreased from 87 to 84 points. The home dialysis patients' perceived health decreased from 3.9 to 3.4 points. Our study shows that psychosocial, but not somatic variables, are prognostically important in survival of older patients undergoing dialysis, and there is a measurable decline in these variables during a three-year follow-up period.

Old patients and uremia: rates of acceptance to and withdrawal from dialysis.

We studied the entry of elderly uremic patients to chronic dialysis in the U.S. in 1979. We also reviewed long-term survival, causes of death, and risk factors for death in old patients on dialysis at one center for the period 1966 to 1983. A comparison of the number of patients at risk with the number entering dialysis in the United States in 1979 indicates that 80% of the patients aged 25-45 years, 30% of patients over the age of 65 years, and 6% of those over the age of 75 years entered dialysis during that period. Of 239 patients over the age of 70 years followed at the Regional Kidney Disease Program at Hennepin County Medical Center in Minneapolis, the seven-year cumulative survival was 17%. In this program withdrawal from dialysis was the commonest cause of death, accounting for 40% of all deaths. Age groups over 75 years, sex, time period, duration of dialysis, eight pre-existing degenerative diseases, living situation, family support, and site and type of dialysis were not risk factors for termination of dialysis, but living in a nursing home was. When compared to the young, total deaths and deaths from discontinuation were much higher, and this decision was made earlier. Half of the patients who died because dialysis was discontinued were competent and decided for themselves; the other half were incompetent and families and physicians made the decision.(ABSTRACT TRUNCATED AT 250 WORDS)

Reoperation on prosthetic heart valves. An analysis of risk factors in 552 patients.

Five hundred fifty-two patients underwent a total of 617 reoperations for repair or replacement of a prosthetic heart valve. Operative mortality for first reoperation (530 patients) was 5.9% for the aortic position and 19.6% for the mitral position. Overall operative mortality was 14% for second reoperation (69 patients) and 7% for third reoperation (14 patients). In addition to valve position, operative mortality for first reoperation appeared to be related to pre-reoperation functional class and urgency of operation. First reoperation for mitral valve patients in New York Heart Association (NYHA) Class II was 4.2%; for Class III, 9.3%; and for Class IV, 41%. In the aortic position, operative mortality was 2.4% for Class I, 1.6% for Class II, 6.3% for Class III, and 20.8% for Class IV. The mortality for elective mitral valve reoperation was 0%; for urgent operation, 20.3%; and for emergency procedures, 54.5%. Elective aortic valve reoperation carried a 1.4% mortality; urgent procedures, 8%; and emergency procedures, 37.5%. No significant differences in bleeding complications were noted between reoperations and initial valve replacement. The data appear to suggest that when significant valve dysfunction is first noted, reoperation should be undertaken to minimize operative risk.