PubMed Health⌕ Search

Biomedical subjects

L W Miller

Publications and source records attributed to L W Miller.

At least 55 records · Page 3Linked to original sources
PubMed1995

Coronary angioplasty, atherectomy and bypass surgery in cardiac transplant recipients.

OBJECTIVES: This study sought to analyze the outcomes of revascularization procedures in the treatment of allograft coronary disease. BACKGROUND: Allograft vasculopathy is the main factor limiting survival of heart transplant recipients. Because no medical therapy prevents allograft atherosclerosis, and retransplantation is associated with suboptimal allograft survival, palliative coronary revascularization has been attempted. METHODS: Thirteen medical centers retrospectively analyzed their complete experience with percutaneous transluminal coronary angioplasty, directional coronary atherectomy and coronary bypass graft surgery in allograft coronary disease. RESULTS: Sixty-six patients underwent coronary angioplasty. Angiographic success (< or = 50% residual stenosis) occurred in 153 (94%) of 162 lesions. Forty patients (61%) are alive without retransplantation at 19 +/- 14 (mean +/- SD) months after angioplasty. The consequences of failed revascularization were severe. Two patients sustained periprocedural myocardial infarction and died. Angiographic restenosis occurred in 42 (55%) of 76 lesions at 8 +/- 5 months after angioplasty. Angiographic distal arteriopathy adversely affected allograft survival. Eleven patients underwent directional coronary atherectomy. Angiographic success occurred in 9 (82%) of 11 lesions. Two periprocedural deaths occurred. Nine patients are alive without transplantation at 7 +/- 4 months after atherectomy. Bypass graft surgery was performed in 12 patients. Four patients died perioperatively. Seven patients are alive without retransplantation at 9 +/- 7 months after operation. CONCLUSIONS: Coronary revascularization may be an effective palliative therapy in suitable cardiac transplant recipients. Angioplasty has an acceptable survival in patients without angiographic distal arteriopathy. Because few patients underwent atherectomy and coronary bypass surgery, assessment of these procedures is limited. Angiographic distal arteriopathy is associated with decreased allograft survival in patients requiring revascularization.

Adolescent↗
PubMed1995

Candidate selection for heart transplantation.

The number of patients referred for heart transplantation continues to increase at a rate well beyond the number of available donors. Further attempts to expand the donor pool may be difficult and certainly cannot keep pace with the increased demand. Uniform criteria for candidate selection are critically needed. Significant functional impairment of cardiac origin, as demonstrated by oxygen consumption treadmill testing on maximal medical therapy, should be documented in all patients before considering definitive evaluation for heart transplant. Patients whose peak oxygen consumption is less than 50% of predicted should be seriously considered for transplantation. Similarly, those patients whose peak VO2 is greater than 60% of predicted probably do not warrant listing as transplant candidates in the absence of other significant risk factors, such as malignant ventricular arrhythmias unresponsive to drug therapy or ongoing ischemia not suitable for revascularization. Application of these fairly simple but definitive guidelines should help significantly reduce the number of patients on the transplant waiting list and allow patients with the greatest survival benefit to receive a graft in a much shorter period of time.

Exercise Test↗
PubMed1994

Eight years' experience with bridging to cardiac transplantation.

Although bridging to cardiac transplantation has become a therapeutic option for transplant candidates whose condition deteriorates while they are awaiting a donor heart, short-term efficacy has not been proved and long-term survival has not been reported. We retrospectively reviewed data on 44 patients who had circulatory assist devices placed as a bridge to transplantation between May 1985 and April 1993. The 35 male and nine female patients ranged in age from 12 to 65 years (mean 43.8 years). Thirty-one patients were supported with 32 Thoratec (18 left ventricular, 14 biventricular), 11 Novacor, and two Jarvik J-7-70 devices. The duration of device support was from 4 hours to 440 days (mean 45.5 days). Fifteen patients did not receive a donor organ because of infection (ten patients), renal failure (five patients), bleeding (nine patients), cerebrovascular accident (three patients), ventricular fibrillation (one patient), and right heart failure (one patient), and all died. Two patients were weaned from support and survived without transplantation. Twenty-seven patients underwent transplantation, and 26 survived (96%). Overall survival was 64% (28/44). Duration of survival ranged from 2 to 96 months (mean 35 months). Among the 28 hospital survivors, there were four late deaths (all transplant recipients) at 3, 6, 14, and 68 months. Posttransplantation actuarial survivals at 1, 5, and 8 years are 88%, 83%, and 66%. Twenty-three of the 24 patients presently alive are in New York Heart Association functional class I. These data demonstrate the short- and long-term efficacy of bridging to transplantation with circulatory support devices. The excellent survival and full functional recovery of patients undergoing transplantation ensure that donor organs are not being "wasted" on the sickest patients.

Actuarial Analysis↗
PubMed1993

What to try while congestive heart failure patients are still ambulatory.

As understanding of the mechanisms of congestive heart failure (CHF) has improved, it has become apparent that the previously applied stepped-care approach (ie, diuretic, digitalis, then vasodilator) is no longer valid. There is compelling evidence that use of vasodilators increases survival in CHF, and angiotensin-converting enzyme (ACE) inhibitors are the vasodilators of choice. Use of an ACE inhibitor in patients with New York Heart Association classes II, III, and IV CHF improves survival over that achieved with use of placebo or direct-acting vasodilators. In patients with asymptomatic left ventricular dysfunction after myocardial infarction, long-term administration of captopril improved survival and reduced morbidity and mortality from major cardiovascular events. Using an ACE inhibitor as preventive therapy in post-myocardial infarction patients without overt CHF but with evidence of muscle dysfunction (ie, left ventricular ejection fraction 40% or less) should be considered. The role of a newer vasodilator (eg, amlodipine besylate [Norvasc]) as an adjunct to therapy remains to be defined. If current theories on the pathophysiology of CHF are correct, continued interest in beta blockers is justified, especially in newer agents that have actual vasodilatory action in addition to their other beneficial properties.

Ambulatory Care↗
PubMed1991

Efficacy and safety of a short-term (6-h) intravenous infusion of dopexamine in patients with severe congestive heart failure: a randomized, double-blind, parallel, placebo-controlled multicenter study.

Dopexamine hydrochloride is a new synthetic catechol that offers a unique profile of adrenergic and dopaminergic activity. In this multicenter, parallel design, placebo-controlled study, 45 patients with functional class III or IV chronic congestive heart failure were randomized to receive a placebo infusion or one of three different doses of dopexamine. After a 2-h dose titration sequence, patients received a 6-h constant dose infusion. During this 6-h period, dopexamine was infused at rates of 1, 2 and 4 micrograms/kg body weight per min in the low, intermediate and high dose groups, respectively. In patients receiving high dose infusion, dopexamine produced a 78% increase in cardiac index associated with a 43% decrease in systemic vascular resistance and 24% increase in heart rate (p less than 0.05 vs. placebo for all three variables). There was a trend (p = NS) toward a moderate increase in cardiac index at low and intermediate doses. In patients randomized to receive dopexamine, right atrial, systemic arterial, pulmonary artery and pulmonary capillary wedge pressures showed minimal change from baseline and did not differ statistically from the placebo response. Very few patients developed adverse reactions related to dopexamine, although five patients randomized to receive high dose and three patients randomized to receive intermediate dose dopexamine required dose reduction because hemodynamic variables exceeded arbitrary safety limits or the patients developed symptoms related to the study medication. dopexamine in higher doses effectively increases cardiac index in association with a reduction in systemic vascular resistance. Additional clinical studies are indicated to evaluate the merits of dopexamine in comparison with other inotropic and vasodilator medications.

Adrenergic Agonists↗
PubMed1991

Endomyocardial biopsies in pediatric patients with no irradiation. Use of internal jugular venous approach and echocardiographic guidance.

Heart transplants in pediatric patients have moved from an experimental, end-stage treatment to a valuable therapy for inoperable congenital heart disease and dilated cardiomyopathies. Cardiac rejection is a frequent problem in children with heart transplants. The technical difficulties of obtaining biopsies in small children have encouraged the use of noninvasive methods of detection although endomyocardial biopsy continues to be the most reliable method of surveillance for cardiac rejection. We examined our experience over 7 years with 4 patients (ages 8 months to 10 years) who had a total of 88 endomyocardial biopsies using echocardiographic guidance. The biopsies were done using a Caves-Schultz biotome via the right internal jugular vein. Biopsies were performed in the procedure room, 61%; pediatric intensive care unit, 18%; hospital private room, 18%; and catheterization laboratory, 3% of the time. At 5.0, 6.5, or 8.5 French biotome was used depending on the size of the patient. Twelve episodes of rejection were detected in these patients. The time for venous access was 17 +/- 15 min, and the biopsies took 25 +/- 11 min using this approach. Biopsies were obtained from the right ventricular free wall, apex, and septum to detect focal rejection for a total of 4-6 tissue samples per biopsy. Neither general anesthesia nor fluoroscopy was needed for these biopsies. Costs ranged from $1120 in the patient room to $1590 in the pediatric intensive care unit. Five different biopsies using a femoral approach with fluoroscopic guidance averaged $2250 and did not include the functional assessment obtained using echocardiography. Using the echocardiogram one can see the ventricular muscle and completely avoid perforation. Thus, this technique is technically feasible in children with few complications at a reduced cost, compared to fluoroscopically guided biopsies.

Biopsy↗
PubMed1990

Outpatient dobutamine for end-stage congestive heart failure.

Eleven patients with refractory class IV congestive heart failure who were not candidates for cardiac transplantation were given iv dobutamine therapy on an outpatient basis. All patients underwent hemodynamic evaluation to confirm a beneficial response to low dose (5 micrograms/kg.min) dobutamine and to establish arrhythmia control both on and off dobutamine before hospital discharge. Six of the 11 patients could not be weaned from dobutamine in hospital and were discharged on continuous infusion (maximum dose, 5 micrograms/kg.min), while four were discharged with an infusion regimen ranging from 3 to 5 consecutive days/wk. All patients had a chronic venous access placed and were instructed on the use of an external battery-powered infusion pump with a container holding a concentrated solution of dobutamine hydrochloride. All infusions were delivered at home on an ambulatory basis. Intravenous drug support was discontinued gradually over an average of 3.2 months; seven of 11 patients were able to be weaned entirely from iv inotropic therapy and were maintained on oral therapy alone. Seven of the 11 patients (six of whom were maintained on oral therapy alone) required no hospital readmission during the infusion or follow-up period.

Adult↗
PubMed1989

Exercise capacity during the first year after cardiac transplantation.

Few data are available examining the influence of perioperative clinical parameters on exercise capacity after cardiac transplantation. Accordingly, 40 patients were studied by metabolic exercise testing early (1 to 3 months) and late (6 to 12 months) after cardiac transplantation. Various clinical parameters, including congestive heart failure class, length of hospital stay, age, cold ischemic time and histologic evidence of rejection were correlated with exercise capacity after transplantation. As expected, peak exercise capacity correlated inversely with both age and length of hospital stay. There was no correlation with preoperative congestive heart failure class or heart rate at rest. Interestingly, there was a statistically significant correlation between cold ischemic time and exercise capacity after transplantation. In addition, increased episodes of rejection during the first 6 months after transplantation resulted in statistically lower exercise capacity at 6 to 12 months after the operation. Thus, ischemic damage during transport of the donor organs and subclinical damage during early rejection may affect clinical status after heart transplantation and may only be apparent during increased physical demand such as exercise.

Adult↗