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Biomedical subjects

K L Baughman

Publications and source records attributed to K L Baughman.

At least 91 records · Page 5Linked to original sources
PubMed1987

Negative inotropic effects of furosemide in the isolated rabbit heart: a prostaglandin-mediated event.

Furosemide is an effective diuretic that initiates a rapid diuresis and peripheral vasodilatation through renal adenylate cyclase inhibition and prostaglandin synthesis. Recently, it has been shown to be associated with activation of the neurohumoral vasoconstrictor mechanism and a further compromise of left ventricular function in patients with heart failure. The present study was performed to investigate the direct effects of furosemide on myocardial performance in the isolated perfused rabbit heart. Furosemide (10(-3) M) caused a significant decrease in developed pressure as well as a similar fall in coronary perfusion pressure. Furosemide also decreased myocardial contractility when the coronary perfusion pressure was kept constant. The change in developed pressure but not the decrease in coronary perfusion pressure could be blocked by treatment with indomethacin. Furosemide did not antagonize rabbit cardiac membrane adenylate cyclase. Therefore, furosemide has a direct inhibitory effect on cardiac contractility that is related to prostaglandin synthesis.

Adenylyl Cyclases↗
PubMed1987

Prophylactic antiarrhythmic therapy of high-risk survivors of myocardial infarction: lower mortality at 1 month but not at 1 year.

To determine whether prophylactic antiarrhythmic therapy influences mortality in high-risk patients after acute myocardial infarction, 143 such patients were randomized in a double-blind individually dose-adjusted, placebo-controlled trial an average of 14 +/- 7 days after myocardial infarction and followed for 1 year. Patients were judged to be at high risk on the basis of (1) ejection fraction less than 40% (n = 60), (2) arrhythmias of Lown class 3 or higher (n = 26), or (3) both (n = 57). Aprindine was chosen because of its long half-life, few side effects, and antiarrhythmic efficacy. Baseline characteristics in the treatment arms did not differ. Holter-detected arrhythmias were reduced in aprindine-treated patients at 3 months (p less than .001) and at 1 year (p less than .001). One patient was lost to follow-up; in the remaining patients 1 year mortality was 20% (28/142; 12 aprindine and 16 placebo). There was no significant difference between the two study arms in overall mortality and sudden death. However, among those who died, median duration of survival was longer in aprindine-treated patients (86 vs 21.5 days) (p = .04). Although antiarrhythmic treatment with aprindine of high-risk patients after myocardial infarction does not affect 1 year survival, mortality appears to be delayed; thus there may be a role for short-term treatment before more definitive therapy such as surgery.

Aprindine↗
PubMed1987

Functional and metabolic consequences of vitamin B-6 deficiency in the rat heart.

The cardiac functional and metabolic consequences of pyridoxine deficiency were studied in rats maintained on a pyridoxine-deficient diet for 10 weeks. Because food intake was diminished in the pyridoxine-deficient rats, a second group of animals was fed a diet restricted to the intake of the pyridoxine-deficient animals. The inotropic response (developed pressure) to an isoproterenol or Ca2+ concentration response curve was measured simultaneously with high energy phosphate levels using a modified Langendorf apparatus and 31P nuclear magnetic resonance spectroscopy. The inotropic response to Ca2+ and isoproterenol was significantly decreased relative to controls in both the food-deprived and the pyridoxine-deficient groups. Developed pressure after adrenergic stimulation was significantly less in the pyridoxine-deficient than in the food-deprived animals. Phosphocreatine and ATP levels were maintained and did not differ among the control, pyridoxine-deficient, and food-deprived groups during isoproterenol and Ca2+ stress, implying that the diminished inotropy was not due to an abnormality in generation of high energy phosphate levels.

Adenosine Triphosphate↗
PubMed1987

Comparative analysis of mechanical and bioprosthetic valves after aortic valve replacement.

Comparative long-term performance characteristics of Björk-Shiley mechanical and bioprosthetic valves were analyzed for patients undergoing aortic valve replacement between 1976 and 1981. A total of 419 patients received either a standard Björk-Shiley (n = 266) or bioprosthetic (porcine, n = 126, or pericardial, n = 27) aortic valve. Cumulative patient follow-up was 1,705 patient-years; the average patient follow-up was 4.1 +/- 2.7 years. Survival data were obtained for all but 11 patients (97% complete follow-up) up to 9 years after operation. Survival at 5 years was 81% +/- 4% (+/- standard error) for Björk-Shiley and for bioprosthetic valve recipients. Valve failure in the Björk-Shiley group was predominantly due to valve-related mortality and did not result from structural failure. Patients with bioprosthetic valves experienced valve failure as a result of prosthetic valve endocarditis and intrinsic valve degeneration. Although patients with bioprostheses experienced a lower incidence of valve-related morbidity than Björk-Shiley valve recipients (p less than 0.03), no difference could be demonstrated in the incidence of valve-related mortality or valve failure at 5 years between bioprosthetic and Björk-Shiley valves. Mortality rate from valve failure was higher for Björk-Shiley (86%, 12/14) than bioprosthetic valves (36%, 5/14) (p less than 0.01).

Actuarial Analysis↗
PubMed1986

De novo refractory ventricular tachyarrhythmias after coronary revascularization.

Twelve of 1,675 patients who underwent coronary artery bypass grafting during a 2.5-year period had new onset, recurrent, sustained ventricular tachyarrhythmia a mean of 27 days (range 2 to 150) postoperatively. No patient had an intra- or perioperative myocardial infarction and all patients were hemodynamically stable and had normal metabolic and electrolytic indexes at the time of ventricular tachyarrhythmia. Preoperative ejection fraction was 39 +/- 10% (mean +/- standard deviation) and all patients had Lown grade II or less ventricular ectopic activity on ambulatory monitoring. Postoperative angiography demonstrated occluded saphenous vein grafts in 3 of 7 patients studied, none of whom had symptoms suggestive of myocardial ischemia. Treatment with conventional antiarrhythmic therapy was unsuccessful in all but 1 patient, and 10 patients were treated with amiodarone and 1 patient with propafenone. Four of these patients also received an automatic implantable defibrillator. Thus, de novo ventricular tachyarrhythmia can occur unexpectedly after coronary artery bypass grafting and may be the result of several factors related to either subclinical graft occlusion or increased dispersion of repolarization secondary to reperfusion.

Aged↗
PubMed1986

Effect of the addition of propranolol to therapy with nifedipine for unstable angina pectoris: a randomized, double-blind, placebo-controlled trial.

The value of the addition of beta-blockers to coronary vasodilator therapy in the treatment of patients with unstable angina at rest is controversial. We conducted a double-blind, randomized, placebo-controlled 4 week trial of propranolol in 81 patients with unstable angina, 39 of whom were assigned to placebo and 42 of whom received propranolol in a dose of at least 160 mg daily. All patients were also treated with coronary vasodilators, including 80 mg nifedipine daily and long-acting nitrates. The incidences of cardiac death, myocardial infarction, and requirement for bypass surgery or coronary angioplasty did not differ between the two groups (propranolol = 16; placebo = 18). The propranolol group had a lower cumulative probability of experiencing recurrent resting angina than the placebo group (p = .013), and over the first 4 days of the trial the mean number of clinical episodes of angina (propranolol 0.9 +/- 0.2, placebo 1.8 +/- 0.3, p = .036), duration of angina (propranolol 15.1 +/- 4.3 min, placebo 38.1 +/- 8.4, p = .014), and nitroglycerin requirement (propranolol 1.1 +/- 0.3 tablets, placebo 3.5 +/- 0.8, p = .003) were also fewer. Continuous electrocardiographic recording for ischemic ST segment changes revealed fewer daily ischemic episodes in the propranolol group (2.0 +/- 0.5) than in the placebo group (3.8 +/- 0.7, p = .03), and a shorter duration of ischemia (propranolol 43 +/- 10 min, placebo 104 +/- 28 min, p = .039). Thus propranolol, in patients with unstable angina, in the presence of nitrates and nifedipine is not detrimental and reduces the frequency and duration of symptomatic and silent ischemic episodes.

Adult↗
PubMed1986

Organization, development and early results of a heart transplant program. The Johns Hopkins Hospital experience.

Improved survival and quality of life have resulted in a resurgence in cardiac transplantation and the proliferation of centers contemplating initiation of a transplant program. Organization of such a program requires cooperation among several clinical and non-clinical departments of the hospital. Prior to implementation of such a program, a number of issues need to be addressed, including state authorization, an expeditious method for donor organ retrieval, protocols for recipient selection and evaluation, and perioperative and follow-up care of the transplant recipient. Since July of 1983, 35 patients (27 men and eight women) have undergone orthotopic cardiac transplantation. Transplantation was undertaken for cardiomyopathy (30) or end-stage ischemic heart disease (5). The mean age was 38 years (range, 16 to 57 yrs). Distant organ procurement was used for 83 percent of patients; mean ischemic time was 164 min (range, 75 to 250 min). Current immunosuppressive regimen consists of oral cyclosporine (10 mg/kg) and prednisone. Mean follow-up was 10.3 months (range, two weeks to 27 months). Transient renal dysfunction appeared early in 15 patients. Six deaths have occurred: three from rejection, one from infection, one from metastatic prostate carcinoma, and one from pulmonary hemorrhage. All but three recent patients have been rehabilitated. These initial encouraging results are a result of careful planning, institutional commitment, adequate resources and, most importantly, a dedicated transplant team.

Adolescent↗
PubMed1986

Cardiomyopathy.

Explore the source record for details and available documents.

Cardiomyopathies↗
PubMed1985

Heart and heart-lung transplantation: program, development, organization, and initiation.

Since the initiation of cardiac transplantation in 1967, more than 1,000 procedures have been done worldwide. A high percentage of these transplant procedures have been completed in the past few years. In 1983, II centers in the United States performed 173 transplant procedures; by 1984, there were more than 30 heart transplant centers. This sudden increase is due primarily to increasing survival of transplant recipients since the introduction of cyclosporine. However, most transplant surgeons believe that the use of this drug alone will not result in survival results and rehabilitation similar to those obtained in experienced transplant centers. Institutional commitment, adequate resources, attention to detail and most importantly, a dedicated transplant team, are important elements to ensure success. This manuscript will define guidelines for the establishment of a new transplant program and eludicate the organizational details necessary to implement such a program, based on our experience at the Johns Hopkins Hospital over the past two years.

Consumer Behavior↗
PubMed1984

Predictors of survival after tricuspid valve surgery.

The long-term survival rate of 74 consecutive patients who underwent multiple cardiac valve surgery including tricuspid valve surgery was analyzed to identify predictive preoperative clinical variables. Univariate analysis revealed that male sex (P less than 0.04), symptoms of New York Heart Association functional class IV heart failure (p less than 0.004), ascites or pulmonary edema (p less than 0.01), high preoperative bilirubin level (p less than 0.012), mean pulmonary artery pressure greater than 40 mm Hg (p less than 0.038) and pulmonary vascular resistance greater than 6 Wood units (p less than 0.02) were each associated with an increased risk of death after surgery. Stepwise multivariate analysis indicated that severity of preoperative edema and mean pulmonary artery pressure were the most predictive combination of independent variables. These 2 variables were used to calculate an estimated probability of 1-year survival after surgery for patients with multivalvular cardiac decompensation. Recognition of these preoperative variables should assist the clinician in determining the risk of surgical intervention.

Adult↗
PubMed1984

Identification of patients at high risk for complications of intraaortic balloon counterpulsation: a multivariate risk factor analysis.

Risk factors for vascular complications of intraaortic balloon (IAB) counterpulsation were evaluated in 206 consecutive patients. The approach was percutaneous in 105 patients and surgical cutdown in 101. Vascular complications occurred in 42 patients, and of these 21 required surgery. Multivariate analysis demonstrated the following major risk factors for vascular complications: preexisting peripheral vascular disease (PVD) defined as a history of claudication, femoral bruit or absent pedal pulse (p less than 0.01); and the use of the percutaneous approach (p = 0.02). Evidence of PVD was particularly predictive of major vascular complications requiring surgery (p less than 0.01). In patients with evidence of previous PVD, the risk for a major vascular complication was 31% with the percutaneous, and 16% with the surgical cutdown approach. Without PVD, the risk for a major vascular complication was 4 times higher in women (15%) than in men (3.5%), but in the presence of PVD gender had no significant effect (p = 0.03). Age, duration of IAB counterpulsation and indication for insertion were not significant risk factors. It is concluded that (1) without previous PVD, women are at greater risk than men for major vascular complications (due to smaller arterial size); and (2) evidence of previous PVD identifies patients at high risk for major vascular complications with IAB counterpulsation, particularly by way of the percutaneous approach.

Assisted Circulation↗
PubMed1984

Operative intervention for postinfarction angina.

Thirty-four patients (26 men and 8 women) underwent myocardial revascularization following myocardial infarction (MI) at the Johns Hopkins Hospital during 1980 through 1982. Average age was 59 years. Of the 33 patients with unstable angina, 61% had ischemia in the infarct zone and 39% had "ischemia at a distance." Mean time from MI to operation was 16 days. The MIs were equally divided between a transmural and a subendocardial location. Eleven patients had a history of congestive heart failure. Intraaortic balloon pumping was used preoperatively for anginal stabilization in 14 patients. Mean ejection fraction for the group was 52%. There were 3 operative deaths, all 3 due to myocardial failure. Late follow-up (mean, 13.7 months; range, 6 to 35 months) is complete for 28 patients. There was 1 late death, secondary to cardiac failure. There were no late MIs. Angina had recurred in 5 patients, but only 2 were taking antianginal medication. At the time of follow-up, 52% of patients were in New York Heart Association Functional Class I. This experience suggests that operative intervention for postinfarction angina can be accomplished with an acceptable mortality and thereby increase survival, reduce the later occurrence of MI, and relieve angina in this high-risk group.

Aged↗
PubMed1984

Acute nifedipine withdrawal: consequences of preoperative and late cessation of therapy in patients with prior unstable angina.

Reports of acute ischemic events after withdrawal of calcium antagonist therapy in outpatients and during bypass surgery in patients with prior angina at rest prompted the examination of the effect of nifedipine withdrawal in 81 patients who had completed a prospective, double-blind randomized trial of nifedipine versus placebo for rest angina. Thirty-nine patients underwent bypass surgery for uncontrolled angina or left main coronary artery disease. No significant difference between patients withdrawn from nifedipine or placebo was seen in the incidence of perioperative myocardial infarction, hypotension requiring intraaortic balloon counterpulsation, vasopressor or vasodilator requirements or incidence of significant arrhythmias. An additional 42 patients had completed 2 years on a protocol consisting of nitrates and propranolol in addition to nifedipine or placebo. During a mean of 66 hours of continuous monitoring after withdrawal of nifedipine or placebo, heart rate and blood pressure were unchanged. A worsening of previously present angina at rest occurred in five patients who had continued to experience rest angina before drug withdrawal, four of whom were withdrawn from nifedipine. No patient with class I to III angina experienced new onset of rest angina during drug withdrawal. No patient experienced myocardial infarction. There was no significant difference between patients withdrawn from nifedipine or placebo in the duration or frequency of ischemic ST changes on continuous electrocardiographic monitoring, or in duration or positive results of serial exercise treadmill testing. Thus, no early adverse effects of acute nifedipine withdrawal were found in patients with prior rest angina at the time of bypass surgery or in stable patients receiving long-term medical therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1983

Transpulmonary artery correction of anomalous origin of the left coronary artery by saphenous vein graft.

A transpulmonary saphenous vein graft was used to repair an anomalous origin of the Left coronary artery from the pulmonary artery (ALCAPA). Postoperative cardiac catheterization revealed correction of the previous systemic arterial to venous shunt and a patent intrapulmonary artery conduit. The patient has experienced substantial symptomatic and functional improvement from the operation operation despite development of mild pulmonary outflow obstruction. Saphenous vein transpulmonary artery correction for ALCAPA offers an alternative surgical approach and may be the procedure of choice when anatomy or prior surgery preclude the more standard modes of revascularization.

Adult↗