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L W Miller

Publications and source records attributed to L W Miller.

At least 37 records · Page 2Linked to original sources
PubMed1997

Long-term cardiopulmonary exercise performance after heart transplantation.

Functional capacity is an important outcome variable for heart transplantation, but there are few data that examine the temporal relation and duration of improvement in cardiopulmonary exercise performance after cardiac transplantation. Cardiopulmonary exercise performance was measured in 140 patients who underwent 426 treadmill exercise tests up to 9 years after cardiac transplantation. Univariate and multivariate analyses were used to predict postoperative improvement in functional capacity. Peak oxygen consumption (VO2) significantly improved from 14.2 +/- 3.7 ml/min/kg before to 21.4 +/- 5.6 ml/min/kg at a mean of 11.2 +/- 3.0 months after the transplant procedure (p < 0.001). When peak aerobic capacity was compared with a normal population, peak VO2 was < 50% of predicted in only 9 patients (12%), from 50% to 70% in 34 patients (44%), from 70% to 90% of predicted in 24 patients (31%); 10 patients (13%) were able to achieve > 90% of peak predicted VO2. The improvement seen at 6 months did not significantly change over 9 years of follow-up. Significant preoperative univariate predictors of.1-year postoperative improvement in peak VO2 were preoperative peak VO2 (p = 0.004), age (p < 0.001), ischemic cardiomyopathy (p = 0.007), and preoperative left ventricular ejection fraction (p < 0.001). Peak VO2 at 1 year in patients able to perform the test was not significantly influenced by acute rejection episodes, donor body surface area, or donor/recipient size ratio. In conclusion, exercise capacity is significantly improved within 6 months after cardiac transplantation, and maintained as long as 9 years after procedure. The magnitude of postoperative improvement is inversely related to preoperative peak VO2 and age.

Adult↗
PubMed1996

Secular trends in cardiac transplant recipient and donor management in the United States, 1990 to 1994. A multi-institutional study. Cardiac Transplant Research Database Group.

BACKGROUND: The growth of the US cardiac transplant waiting list has outpaced the increase in donors, resulting in a widening gap between the number of waiting recipients and available donors. These trends have generated concern that longer waiting times may result in more patients deteriorating to urgent status and that transplanting only patients who are in an advanced state of decompensation will reduce posttransplant survival. Furthermore, the shortage of donors may result in extending the guidelines for donor acceptability to a degree that increases graft failure and posttransplant mortality. We measured these secular trends in the Cardiac Transplant Research Database to provide current data on time-dependent changes in US cardiac transplant practice and survival. METHODS AND RESULTS: At the time of this analysis, the Cardiac Transplant Research Database included all 2749 patients transplanted from January 1, 1990, to June 30, 1994, in the 25 participating transplant centers. During this 4.5-year period, the median waiting time for recipients who received a transplant increased from 2.7 to 3.5 months (P < .0001), and the proportion of recipients whose status was urgent at transplantation increased from 41% to 60% (P < .0001). Donor ischemic time increased from 150 to 166 minutes (P < .0001), and the proportion of donors requiring pressor support increased from 68% to 85% (P < .0001). Despite these changes in practice, the 1-year survival rate remained constant at 84% during this 4.5-year interval. There was no significant difference in 1-year survival rate between urgent status patients (83%) and nonurgent status patients (85%) (P = .08). CONCLUSIONS: The widening gap between the number of waiting recipients and the number of donors has resulted in a continuing trend toward transplanting urgent status recipients and to a liberalization of donor acceptance criteria. Despite these changes, posttransplant survival has remained constant.

Adult↗
PubMed1996

Variations in normal coronary vasodilatory reserve stratified by artery, gender, heart transplantation and coronary artery disease.

OBJECTIVES: The purpose of the study was to assess the spectrum of coronary vasodilatory reserve values in patients with angiographically normal arteries who had atypical chest pain syndromes or remote coronary artery disease or were heart transplant recipients. BACKGROUND: The measurement of post-stenotic coronary vasodilatory reserve, now possible in a large number of patients in the cardiac catheterization laboratory, is increasingly used for decision making. Controversy exists regarding the range of normal values obtained in angiographically normal coronary arteries in patients with different clinical presentations. METHODS: Quantitative coronary arteriography was performed in 214 patients classified into three groups: 85 patients with chest pain syndromes and angiographically normal arteries (group 1); 21 patients with one normal vessel and at least one vessel with > 50% diameter lumen narrowing (group 2); and 108 heart transplant recipients (group 3). Coronary vasodilatory reserve (the ratio of maximal to basal average coronary flow velocity) was measured in 416 arteries using a 0.018-in. (0.04 cm) Doppler-tipped angioplasty guide wire. Intracoronary adenosine (8 to 18 micrograms) was used to produce maximal hyperemia. RESULTS: Coronary vasodilatory reserve was higher in angiographically normal arteries in patients with chest pain syndromes (group 1:2.80 +/- 0.6 [group mean +/- SD]) than in normal vessels in patients with remote coronary artery disease (group 2: 2.5 +/- 0.95, p = 0.04); both values were significantly higher than those in the post-stenotic segment of the diseased artery (1.8 +/- 0.6, p < 0.007). Coronary vasodilatory reserve in transplant recipients (group 3) was higher than that in the other groups (3.1 +/- 0.9, p < 0.05 vs. groups 1 and 2) as a group and for individual arteries. When stratified by vessel, coronary vasodilatory reserve was similar among the left anterior descending, left circumflex and right coronary arteries. There were no differences between coronary vasodilatory reserve values on the basis of gender for patients with coronary artery disease and transplant recipients. In group 1 (chest pain), there was a trend toward higher coronary vasodilatory reserve in men than in women (2.9 +/- 0.6 vs 2.7 +/- 0.6, p = 0.07). CONCLUSIONS: These findings identify a normal reference range for studies assessing the coronary circulation and post-stenotic coronary vasodilatory reserve in patients with and without coronary artery disease encountered in the cardiac catheterization laboratory.

Aged↗
PubMed1996

Hemodynamic effects of a single intravenous injection of synthetic human brain natriuretic peptide in patients with heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

Synthetic human brain natriuretic peptide (sBNP) is a polypeptide with the same amino acid sequence as the naturally occurring hormone. Preclinical studies have demonstrated that BNP has potent hemodynamic, diuretic, and natriuretic effects that might be beneficial in treating patients with heart failure. This study was a randomized, double-blind, placebo-controlled, ascending-dose trial of sBNP administered as a single intravenous bolus in 27 heart failure patients. Six groups of patients received sequentially increasing doses of sBNP (0.3, 1, 3, 10, 15, and 20 micrograms/kg, respectively) as a single intravenous injection, and hemodynamics were assessed by pulmonary artery monitoring catheter. The 10 and 15 micrograms/kg doses of sBNP resulted in significant reductions in pulmonary capillary wedge pressure (-73%, p < 0.001), mean pulmonary artery pressure (-41%, p < 0.001), mean arterial blood pressure (-28%, p = 0.001), and systemic vascular resistance (-53%, p = 0.004). Significant increases occurred in cardiac index (68%, p < 0.001) and stroke volume index (72%, p < 0.001). The magnitude and duration of hemodynamic changes were dose dependent. There were no adverse effects. sBNP injected as a single intravenous bolus in heart failure patients improves hemodynamics in a dose-related fashion. Further clinical investigations to determine the use of sBNP in decompensated heart failure are clearly warranted.

Cardiomyopathy, Dilated↗
PubMed1996

Prognostic value of cardiopulmonary exercise testing using percent achieved of predicted peak oxygen uptake for patients with ischemic and dilated cardiomyopathy.

OBJECTIVES: We tested the hypothesis that percent achieved of predicted peak oxygen uptake (predicted VO2max) improves the prognostic accuracy of identifying high risk ambulatory patients with congestive heart failure considered for heart transplantation compared with absolute peak oxygen uptake (VO2max) in 181 patients with ischemic or dilated cardiomyopathy. BACKGROUND: Peak oxygen uptake during exercise has been shown to be a useful prognostic measurement to risk stratify patients with heart failure. The prognostic value of percent predicted VO2max has not been assessed in these patients. METHODS: We retrospectively studied 181 ambulatory patients referred to the Saint Louis University Heart Failure Unit. Clinical, hemodynamic (137 patients) and coronary angiographic (145 patients) data were recorded, and all patients underwent symptom-limited cardiopulmonary exercise. RESULTS: During a mean follow-up period of 12 +/- 6 months, 26 patients died, and 18 were listed as Status 1 priority for heart transplantation. The actuarial 1- and 2-year survival of the 89 patients who achieved < or = 50% predicted VO2max was 74% and 43%, respectively, compared with 98% and 90% in the 92 who achieved > 50% predicted VO2max (p = 0.001). Multivariable analysis selected < or = 50% predicted VO2max as the most significant predictor of cardiac death (p = 0.007) and cardiac death or Status 1 priority (p = 0.0005). CONCLUSIONS: Percent achieved of predicted VO2max provides important information that can be used to risk stratify ambulatory patients with heart failure with ischemic or dilated etiology that exceeds that provided by measurement of VO2max alone. Patients who achieve > 50% predicted VO2max have an excellent short-term prognosis when treated medically, and heart transplantation can be safely deferred.

Cardiomyopathy, Dilated↗
PubMed1996

Psychological and cognitive status before and after heart transplantation.

Advances in the technical aspects of heart transplantation and the medical management of rejection have allowed a shift toward research evaluating psychological factors affecting heart transplant candidates and psychosocial sequelae following transplantation. This study examined the psychological and cognitive status of patients presenting for heart transplant evaluation. The findings indicated that this patient group was characterized by impaired verbal memory and a tendency toward depression and anxiety. The second part of the study examined changes in psychological and cognitive status from the initial evaluation to a follow-up assessment 1 year after transplantation. The results indicated that psychological distress (depression, anxiety) and several indices of cognitive function improved after transplantation. Finally, correlations were determined to evaluate the association between the psychological and cognitive measures and episodes of rejection in the first 6 months after transplantation. Anxiety, depression, and a nonverbal measure of intelligence were found to be associated with the number of episodes of rejection. The implications of these findings are discussed.

Adult↗
PubMed1996

The surgical management of allograft coronary disease: a paradigm shift.

The surgical options for heart transplant recipients who develop obstructive coronary artery disease in their allograft have historically been limited to retransplantation. Given the worse outcome in recipients of second grafts, often caused by recurrence of coronary disease, coupled with the significant increase in the number of patients on the transplantation waiting lists, has made retransplantation a limited option. However, as heart transplant recipients continue to live longer, there are an increasing number of patients who develop allograft coronary disease. Coronary bypass surgery has not been offered to these patients because of numerous pathology reports describing uniform involvement of the coronary vessel from its origin to the distal intramural branches, thereby eliminating any reasonable runoff vascular bed to handle increased flow that might be delivered with bypass conduits. However, new diagnostic techniques such as measurement of coronary flow reserve by Doppler flow wire can define the physiological vasodilating capacity or reserve which, if normal, should allow conventional bypass surgery if adequate target epicardial vessels are present. This approach would allow a more reasonable alternative to many patients who otherwise would die of this disease without any intervention. Other alternatives such as transmyocardial laser revascularization are discussed.

Coronary Disease↗
PubMed1995

Influence of intimal thickening on coronary blood flow responses in orthotopic heart transplant recipients. A combined intravascular Doppler and ultrasound imaging study.

BACKGROUND: Intravascular ultrasound imaging detects epicardial intimal thickening in the majority of heart transplant recipients with angiographically normal epicardial coronary arteries. Although coronary artery vasoreactivity is abnormal after cardiac transplantation, intimal thickening does not appear to affect conduit vessel responses. However, the effect of intimal thickening on both conduit and resistance vessel responses, as measured by changes in volumetric coronary blood flow (CBF), is unknown. METHODS AND RESULTS: Epicardial coronary artery conductance and microvascular resistance vessel responses were studied after intracoronary adenosine and nitroglycerin administration in 36 orthotopic heart transplant recipients 1 month to 7 years after transplantation. Sequentially measured coronary flow average peak velocity ([APV, cm/s] 0.018 in Doppler guide wire) and epicardial luminal cross-sectional area ([CSA, mm2] 4.3F 30-MHz ultrasound catheter) data were obtained at baseline and during peak hyperemia after administration of 12 to 18 micrograms IC adenosine and 150 to 200 micrograms IC nitroglycerin. Volumetric CBF (mL/min) was calculated as CBF = APV (cm/s) x CSA (mm2) x 60 seconds/1 min x 1 cm2/100 mm2 x 0.5. Measurements were made from a discrete position in the proximal left anterior descending (LAD) artery (n = 22), mid-LAD artery (n = 7), proximal circumflex artery (n = 6), and proximal right coronary artery (n = 1). Intimal thickening was present in 19 of 32 patients (60%). Both adenosine and nitroglycerin increased APV (from 18.9 +/- 4.9 to 56.0 +/- 11.5 cm/s for adenosine and from 20.2 +/- 5.3 to 49.1 +/- 11.5 cm/s for nitroglycerin; both P < .05). Coronary flow velocity reserve was significantly higher for adenosine compared with nitroglycerin (3.1 +/- 0.6 versus 2.5 +/- 0.7, respectively; P < .001). Epicardial luminal CSA was unchanged during adenosine hyperemia compared with baseline (17.4 +/- 3.8 versus 17.3 +/- 4.0 mm2, respectively; P = NS) but was significantly greater during nitroglycerin hyperemia compared with baseline (18.7 +/- 3.8 versus 17.3 +/- 4.0 mm2, 6.2 +/- 3.6% change; P < .05). Baseline CBF was similar before drug administration. Hyperemic adenosine and nitroglycerin CBF responses (297 +/- 99 and 276 +/- 87 mL/min, respectively; P = NS) and CBF reserve (3.0 +/- 0.7 and 2.7 +/- 0.7, respectively; P = NS) were not significantly different. Importantly, intimal thickening did not diminish resting or hyperemic APV, coronary flow velocity reserve, luminal CSA, CBF, or CBF reserve responses. CONCLUSIONS: In this study of angiographically normal heart transplant recipients, epicardial intimal thickening does not diminish conduit and resistance vessel responses during endothelial-independent vasodilator administration.

Adenosine↗
PubMed1995

A standardized technique for establishing onset and duration of symptoms of Alzheimer's disease.

OBJECTIVES: To develop an informant-based semistructured interview to determine the onset and duration of symptoms of Alzheimer's disease, and to use this instrument with informants to characterize a cohort of mildly impaired patients with Alzheimer's disease. DESIGN: In study 1, interrater and interinformant reliability was examined for the date of onset and the order of appearance for specific symptoms that were elicited by the semistructured onset interview. In study 2, the instrument was used to characterize disease onset in a cohort of patients with Alzheimer's disease who were participating in a large multicenter study. SUBJECTS: Informants of patients with Alzheimer's disease. RESULTS: In study 1, interrater reliability for duration of illness was excellent (intraclass correlation coefficient = .99, P < .001), and interinformant reliability was good (intraclass correlation coefficient = .86, P < .001). Agreement for the presence of a given symptom was highest for those that were most commonly reported (eg, memory and performance difficulty). In study 2, 89% of the cohort had memory problems, and 63.9% had performance difficulties as the first or second symptom. Depression and language problems were less commonly reported. Psychosis and behavioral disturbances were rarely reported as the first problem. CONCLUSION: This instrument provides a reliable procedure for standardizing the estimation of duration of illness based on retrospective report.

Aged↗
PubMed1995

Fetal growth and the etiology of preterm delivery.

OBJECTIVE: To confirm that preterm delivery is associated with fetal growth restriction (FGR), and to determine if the various etiologies of preterm delivery are associated with the same degree and type of FGR. METHODS: Two hundred ninety young, primarily minority gravidas who had routine initial ultrasound examinations also had subsequent ultrasound examinations at 32 weeks' gestation. Fetal growth characteristics were compared between preterm (less than 37 weeks' gestation) and term deliveries, and among preterm deliveries with medical or obstetric indications, premature rupture of membranes (PROM), and spontaneous preterm labor. RESULTS: Forty-six infants (15.9%) were born preterm. At 32 weeks' gestation, all fetuses later delivered preterm were already smaller than fetuses later delivered at term (P < .05) for all dimensions: head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL). However, after stratifying by cause of preterm delivery for those fetuses later delivered for medical or obstetric indications, we found that only AC was decreased (P < .01) and that the HC-AC ratio was elevated (asymmetric FGR). Neonates delivered after unsuccessfully treated PROM or preterm labor were symmetrically smaller in all characteristics (HC, AC, BPD, and FL). CONCLUSION: By 32 weeks' gestation, fetuses later delivered preterm are already significantly smaller than fetuses later delivered at term. However, when stratified by the etiology of preterm delivery, infants delivered preterm for medical or obstetric indications had asymmetric growth patterns, which suggests a growth failure late in pregnancy. Infants delivered preterm after PROM or after failed or no tocolysis for spontaneous preterm labor were proportionately smaller, implying an overall slowing of growth that may originate early in pregnancy and possibly demonstrate a more chronic stress.

Adult↗