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Biomedical subjects

L R McBride

Publications and source records attributed to L R McBride.

At least 19 recordsLinked to original sources
PubMed2001

Postpartum coronary artery dissection complicated by heparin-induced thrombocytopenia and thrombosis.

A 32-year-old woman presented with an acute anterior-lateral myocardial infarction 7 days postpartum. Coronary angiography revealed an occlusive left main coronary artery dissection. After coronary artery bypass surgery the patient's cardiac function improved and stabilized. Thrombocytopenia and a femoral artery thrombosis after 9 days of heparin exposure marked the development of heparin-induced thrombocytopenia and thrombosis that was successfully managed with argatroban, a direct thrombin inhibitor anticoagulant.

Adult↗
PubMed2001

Risk analysis in patients bridged to transplantation.

BACKGROUND: Efforts to predict mortality in bridge to cardiac transplant patients have concentrated on preventricular assist device (VAD) status. To more fully identify factors influencing survival to transplant, we reviewed the preoperative and postoperative VAD courses of 105 bridge to transplant patients. METHODS: Sixty-four parameters (34 pre-VAD, 30 post-VAD), including hemodynamics, complications, and evaluations of major organ function were examined and analyzed. RESULTS: Thirty-three patients (31%) died on VADs and 72 were transplanted. There were two posttransplant operative deaths (3%). By univariate analysis 23 of 64 factors were significant. These 23 factors were entered into a stepwise logistic regression analysis to identify predictors of survival to transplant. Four factors, including pre-VAD intubation (p < 0.005), cardiopulmonary bypass (CPB) time during VAD insertion (p < 0.0001), mean pulmonary artery pressure (first postoperative day after VAD) (p < 0.0002), and highest post-VAD creatinine (p < 0.01) were independent predictors of transplantation. CONCLUSIONS: Other than the need for intubation, pre-VAD variables were of little value in predicting survival to transplant. Problems during VAD insertion (long CPB time) and post-VAD renal insufficiency were independent predictors. Severe complications that developed during the interval of VAD support, including cerebrovascular accident, bleeding and infection, were surprisingly not predictors for transplantation.

Actuarial Analysis↗
PubMed2001

Multicenter experience with the thoratec ventricular assist device in children and adolescents.

BACKGROUND: Patient size is 1 determinant in selecting a mechanical circulatory support device. The current pulsatile ventricular assist devices (VADs) were designed primarily for average-sized adults. The flexibility of the Thoratec VAD, however, has encouraged physicians to use it in a significant number of intermediate-sized older children and adolescents. METHODS: We conducted a retrospective study in 58 children and adolescents <18 years (41 boys, 17 girls) who had been supported with the Thoratec VAD in 27 centers worldwide as of December 1999. Mean patient age was 13.8 years (range, 7 to 17 years), and mean patient weight and body surface area were 51.6 kg (range, 17 to 93 kg) and 1.5 m(2) (range, 0.7 to 2.1 m(2)), respectively. RESULTS: Thirty-five patients (60%) survived to transplantation and 6 (10%) to recovery of the native heart, respectively; 38 were discharged from the hospital (66%). In the transplanted group, post-transplantation survival was 97%. Patient age and size were not associated with significantly increased risk for death or adverse events. Fifteen patients (27%) had 18 neurologic events during support, and 6 of these were fatal. Left atrial cannulation proved a risk factor for neurologic complications. CONCLUSIONS: The Thoratec VAD has successfully been used in a large number of children and adolescents with similar morbidity and mortality results as with adults. The risk of neurologic complications may be increased, particularly in patients cannulated in the left atria.

Adolescent↗
PubMed2000

Transfer of patients receiving advanced mechanical circulatory support.

OBJECTIVE: Improving results with ventricular assist devices have led to their wider clinical application. Centers can stabilize, support, and wean or transfer patients to regional transplant centers. METHODS: Prospectively collected data were reviewed to evaluate the clinical results of patients transferred to our institution while receiving advanced mechanical circulatory support. RESULTS: Since 1993, 16 patients were accepted while receiving support with either extracorporeal membrane oxygenation or a ventricular assist device. The 10 male and 6 female patients ranged in age from 9 to 60 years (mean, 42.1 years). Thirteen had had cardiac surgical procedures, two had acute myocardial infarctions, and one had myocarditis. The distance transported ranged from 0.2 to 309 miles (mean, 132 miles). Twelve patients were transferred by ground, and 4 were transported by air. Seven patients were originally supported with extracorporeal membrane oxygenation, 6 with centrifugal pumps, and 3 with ABIOMED ventricular assist devices (ABIOMED, Inc, Danvers, Mass). Two patients had clinical complications during transfer, and one had a cerebrovascular accident, recovered, was weaned, and survived. A second patient had hemodynamic deterioration. There were no technical complications associated with transport. Six patients were left on the original support device; 3 of the 6 were weaned and survived, and 3 died during support. The 10 remaining patients were switched to other ventricular assist devices: 9 patients to Thoratec devices (Thoratec Laboratories, Pleasanton, Calif) and 1 patient to a Novacor device (Baxter Healthcare Corp, Novacor Division, Oakland, Calif). Six of the 10 patients underwent transplantation and survived. Four patients died while being supported by the devices. Nine patients were discharged, with 1 late death at 29 months. Eight patients are alive 4 to 65 months after discharge. CONCLUSIONS: These data suggest that patients receiving advanced support can be moved between clinical centers with acceptable risks. Because 33% of the survivors were weaned, transplantation is not required for survival.

Adolescent↗
PubMed1999

Clinical experience with 111 thoratec ventricular assist devices.

BACKGROUND: Ventricular assist devices (VADs) have gained wider acceptance due to refinements in patient selection and management and device availability. METHODS: To evaluate early and late results, we reviewed our first 111 patients with the Thoratec VAD. RESULTS: Forty-four patients were supported for myocardial recovery. The mean age in the recovery group was 51.9 years. There were 18 left VADs (LVADs), 17 biventricular VADs (BVADs), and nine right VADs (RVADs). Complications included bleeding in 20 patients (45%) and device-related infection in 1 patient (2%). Nineteen were weaned from the VAD, with 12 survivors. Sixty-seven patients were supported as a bridge to cardiac transplantation. The mean age was 41.5 years. There were 39 LVADs and 28 BVADs. Complications included bleeding in 21 patients (31%) and device-related infection in 12 (18%). Three patients were weaned and 39 patients were transplanted from the assist device, for a total of 42 bridge survivors. Device-related thromboembolism occurred in 9 patients (8.1%), 7 of whom were bridge to transplantation. The duration of VAD support ranged from 0.1 to 27 days (mean 4.5 days) in the recovery group and 0.2 to 184 days (mean 40.7 days) in the bridge to transplantation group. The 10-year actuarial survival was 16% for the recovery group, 22%, for the bridge group, and 33% for transplanted patients. CONCLUSIONS: Despite advances, VAD support remains associated with significant morbidity and operative mortality.

Adolescent↗
PubMed1999

Ventricular assist device support in patients with mechanical heart valves.

BACKGROUND: Due to potential thromboembolic complications, mechanical valves within the native heart are often considered contraindications to ventricular assist device (VAD) support. METHODS: A retrospective review of VAD cases between June 1982 and March 1998 showed 8 patients with mechanical valves who were supported with Thoratec (Pleasanton, CA) VADs. RESULTS: There were 6 males and 2 females ranging in age from 20 to 69 years (mean 49.8+/-5.6). Four patients were supported when they could not be weaned from cardiopulmonary bypass after reparative procedures and were thought to have reversible injuries. Four patients were supported as a bridge-to-cardiac transplantation. Two patients had mechanical mitral valves, 2 had aortic valve replacements, 1 had an aortic homograft and mechanical mitral valve, 2 had mechanical aortic and mitral prosthesis, and 1 patient had aortic, mitral, and tricuspid valves. The types of valvular prostheses were St. Jude (5 patients) and Bjork-Shiley (3 patients). Duration of support ranged from 3.0 to 150 days (mean 34 days). Four patients were supported with biventricular assist devices and 4 had left VADs. Dextran and intravenous heparin anticoagulation were used in the shorter duration patients, with warfarin being used in the bridge patients. One patient received warfarin and aspirin. At the time of autopsy or device removal, only 1 of the 12 mechanical intracardiac valves showed any evidence of thrombosis, including the aortic valves in 2 patients supported for 2 and 5 months. There were no clinical thromboembolic events. Four patients (50%) were discharged (1 weaned, 3 transplanted). CONCLUSIONS: The 50% (4 of 8) survival rate compares favorably with the 44% (41 of 92) overall survival rate for our Thoratec patients (bridge plus recovery) who did not have mechanical prosthetic valves. These data suggest that patients with mechanical intracardiac valves can be supported for short durations with some additional risk, which is yet to be determined.

Adult↗
PubMed1998

Right ventricular infarction during left ventricular assist system support.

Left ventricular assist devices are frequently used to bridge patients to cardiac transplantation. As this experience grows, new and unanticipated complications will occur. This report describes a 50-year-old man with ischemic cardiomyopathy being bridged to cardiac transplantation who suffered an acute right ventricular infarction during the interval of support.

Fatal Outcome↗
PubMed1998

Mitral valve replacement: randomized trial of St. Jude and Medtronic Hall prostheses.

BACKGROUND: This study was designed to better define the merits of the bileaflet and tilting-disc valves. METHODS: We prospectively randomized 156 patients (mean age, 59 years) to receive either the St. Jude (n = 80) or the Medtronic Hall (n = 76) mitral valve prosthesis between September 1986 and December 1997. The two groups were not significantly different with respect to preoperative New York Heart Association class, left ventricular ejection fraction, incidence of mitral stenosis or insufficiency, extent of coronary artery disease, completeness of revascularization, or cross-clamp or bypass time. RESULTS: The operative mortality (11.2% versus 13.1%, St. Jude versus Medtronic Hall, respectively) and late mortality (27% versus 22%, St. Jude versus Medtronic Hall, respectively) were not significantly different. Follow-up was complete in all hospital survivors with a mean of 60.7 months (range, 1 to 133 months). The analysis of 10-year actuarial survival and freedom from valve-related events demonstrated no significant differences between the cohorts. Freedom from reoperation was higher in the St. Jude group (p < 0.01). Comparisons of patient functional status and echocardiographic hemodynamic parameters obtained at the time of follow-up demonstrated no significant differences between the two prostheses. CONCLUSIONS: This study suggests that there is no difference between the St. Jude and Medtronic Hall prostheses with respect to late clinical performance or hemodynamic results and therefore does not support the preferential selection of either prosthesis.

Aged↗
PubMed1998

Cardiac assist devices.

During the latter half of the twentieth century, physicians have had the capability to support the circulation with mechanical devices. This article gives an historical overview of those devices. Various devices and their complications are described and evaluated. Patient selection and clinical results also are discussed.

Adult↗
PubMed1997

Preoperative and postoperative comparison of patients with univentricular and biventricular support with the thoratec ventricular assist device as a bridge to cardiac transplantation.

OBJECTIVES: The goal of this study was to determine whether there are differences in populations of patients with heart failure who require univentricular or biventricular circulatory support. METHODS: Two hundred thirteen patients who were in imminent risk of dying before donor heart procurement and who received Thoratec left (LVAD) and right (RVAD) ventricular assist devices at 35 hospitals were divided into three groups: group 1 (n = 74), patients adequately supported with isolated LVADs; group 2 (n = 37), patients initially receiving an LVAD and later requiring an RVAD; and group 3 (n = 102), patients who received biventricular assistance (BiVAD) from the beginning. RESULTS: There were no significant differences in any preoperative factors between the two BiVAD groups. In the combined BiVAD groups, pre-VAD cardiac index (BiVAD, 1.4 +/- 0.6 L/min per square meter, vs LVAD, 1.6 +/- 0.6 L/min per square meter) and pulmonary capillary wedge pressure (BiVAD, 27 +/- 8 mm Hg, vs LVAD, 30 +/- 8 mm Hg) were significantly lower than those in the LVAD group, and pre-VAD creatinine levels were significantly higher (BiVAD, 1.9 +/- 1.1 mg/dl, vs LVAD, 1.4 +/- 0.6 mg/dl). In addition, greater proportions of patients in the BiVAD groups required mechanical ventilation before VAD placement (60% vs 35%) and were implanted under emergency conditions than in the LVAD group (22% vs 9%). The survival of patients through heart transplantation was significantly better in patients who had an LVAD (74%) than in those who had BiVADs (58%). However, there were no significant differences in posttransplantation survival through hospital discharge (LVAD, 89%; BiVAD, 81%). CONCLUSION: Patients who received LVADs were less severely ill before the operation and consequently were more likely to survive after the operation. As the severity of illness increases, patients are more likely to require biventricular support.

Heart Transplantation↗
PubMed1997

Valve replacement in the small aortic annulus: prospective randomized trial of St. Jude with Medtronic Hall.

OBJECTIVE: The ideal prosthesis for aortic valve replacement in patients with small annuli remains controversial and has yet to be identified. The purpose of this report is to compare the St. Jude (SJ) Medical and Medtronic Hall (MH) valves for aortic valve replacement in the small aortic root. METHODS: From 1986 to 1994 we prospectively randomized 456 patients to receive either the SJ or the MH valve. From this population, 80 patients (SJ, 42 patients; MH 38 patients) had a 19 or 21 mm aortic prosthesis inserted without annulus enlarging procedure. RESULTS: Follow-up was complete in all 80 patients for 270 patient years (mean 40.5 months). Analysis showed that the SJ and MH groups were similar with respect to age, gender, body surface area, valve area, NYHA class, ventricular function, prosthesis size, frequency of revascularization, bypass and global ischemic time. There were two operative deaths (1 SJ, 1 MH). Clinical performance and Dobutamine stress transesophageal doppler echocardiography could not demonstrate a significant advantage of one prosthesis over the other in this population. The change in aortic valve gradient, and left ventricular mass index measured preoperatively and within 12 months postoperatively were not different in both cohorts. CONCLUSION: The study could not detect a difference in the performance of the SJ and MH heart valves for aortic valve replacement in patients with small aortic annuli.

Adult↗
PubMed1996

Management of asymptomatic mild aortic stenosis during coronary artery operations.

BACKGROUND: Management of asymptomatic mild aortic stenosis at the time of coronary artery bypass grafting (CABG) remains controversial. We have retrospectively analyzed a cohort of patients requiring aortic valve replacement (AVR) subsequent to CABG and compared their operative morbidity and mortality with that of a group receiving CABG and AVR simultaneously at the first operation. METHODS: Analysis is drawn from 28 patients who required AVR 8 +/- 4 years subsequent to CABG (group A) and 175 patients receiving AVR along with CABG at the primary operation (group B). Groups were similar with respect to age, sex, risk factors for cardiac disease, extent of coronary artery disease, left ventricular function, New York Heart Association class, aortic valve area, number of grafts, and size of prosthesis inserted. RESULTS: Patients having AVR subsequent to CABG had a significantly prolonged aortic cross-clamp time and global myocardial ischemic time and incurred a twofold increase in operative mortality. The actuarial survival at 10 years was not significantly different between cohorts. In the 28 patients in group A, the aortic valve area during the period between operations decreased 0.05 mm2/y. CONCLUSIONS: The operative mortality and morbidity of a second operation for AVR is high, but there is no significant difference in survival at 10 years. In at least a portion of patients having mild aortic stenosis at the time of CABG there will be progression of the stenosis necessitating reoperation at a later date.

Actuarial Analysis↗
PubMed1995

Relation between pulmonary venous flow and pulmonary wedge pressure: influence of cardiac output.

Multiple factors affect the systolic and diastolic components of pulmonary venous flow. It has been suggested that left ventricular function might influence the effects of filling pressures on indexes of pulmonary venous flow. The present study was designed to evaluate the effect of the pulmonary wedge pressures, left ventricular function, and cardiac output on the pulmonary vein flow pattern. Forty-five patients undergoing cardiac surgery were included in this study. Pulmonary venous flow and mitral flow variables were obtained by transesophageal echocardiography with hemodynamic variables obtained simultaneously. In the total group, there was no consistent relation between the pulmonary venous flow or the mitral flow parameters and the capillary wedge pressures. When patients were grouped according to normal (> 2.2 L/min/m2) or low (< 2.2 L/min/m2) cardiac index, a significant and positive relation was found between the systolic component of the pulmonary venous flow and the pulmonary wedge pressure in patients with normal cardiac index (r = 0.69; p = 0.003). Conversely, in patients with low cardiac index there was also a significant although negative correlation between the systolic velocity integral and the pulmonary wedge pressure (r = -0.58; p < 0.001). In conclusion, the systolic component of the pulmonary venous flow correlates closely and significantly with the capillary wedge pressures. The direction of this relation depends to a large extent on the total cardiac output and to a lesser extent on the left ventricular systolic function as assessed by the ejection fraction.

Adult↗
PubMed1994

Risk stratification in patients bridged to cardiac transplantation.

Patient selection is considered one of the most important factors influencing success in bridge to transplant procedures. However, to date it has been difficult to identify predictors of mortality in this population using univariate or multivariate analysis. In 1988, we developed a scoring system using 21 clinical variables that could be calculated rapidly at the bedside while evaluating potential candidates. Points were designated to these variables using a scale of 1 to 3, 1 having the least adverse effect on survival and 3 the most. Patients received a value of 0 for each variable that did not apply. This scoring system was used in a retrospective analysis for 15 bridge to transplant patients. The results showed a significant difference (p < 0.003) between the 8 survivors (mean score, 5.75 +/- 2.19) and the 7 nonsurvivors (mean score, 11.71 +/- 3.45). Since 1989, we have prospectively calculated the scores in an additional 27 patients. Based on the score, all 42 patients were divided into three groups: group I had scores of 1 to 5; group II, 6 to 10; and group III, 11 to 16. The mean score for group I (16 patients) was 3.69 +/- 1.25. All group I patients survived. Group II patients (n = 15) had a mean score of 7.87 +/- 1.36 and a survival rate of 53%. The mean score for group III (n = 11) was 13 +/- 1.73. Thirty-six percent of these patients survived. Comparison of survival and mean scores among the three groups was statistically significant (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗