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Biomedical subjects

O H Frazier

Publications and source records attributed to O H Frazier.

At least 37 records · Page 2Linked to original sources
PubMed2005

Direct thrombolytic therapy for intraventricular thrombosis in patients with the Jarvik 2000 left ventricular assist device.

One of the complications that can occur with continuous, axial-flow left ventricular assist devices (LVADs) is thrombosis within the left ventricle, adjacent to the device's inflow conduit, which may cause inflow obstruction and recurrent heart failure. We describe 2 cases in which we used a catheter to continuously infuse recombinant tissue plasminogen activator (tPA) into the left ventricle until signs of successful thrombolysis was achieved. By monitoring the result and administering only as much tPA as necessary to achieve thrombolysis, we were able to successfully lyse the obstructing thrombus with a minimal dose of tPA without causing any significant bleeding problems. This technique may be useful for managing this potentially serious complication while minimizing the risk of treatment.

Cardiac Catheterization↗
PubMed2005

Factors predicting 10-year survival after heart transplantation.

BACKGROUND: We sought to identify factors predictive of long-term (>10-year) survival in heart transplant (HTx) recipients. METHODS: Four hundred fifteen adult patients underwent HTx at our institution between August 1982 and May 1997. The 158 patients who survived >10 years (Group A) and the 116 patients who died between 2 and 6 years (Group B) of HTx were compared in terms of gender, gender mismatch, ethnicity, age, height, weight, United Network for Organ Sharing status, type of induction therapy (OKT3 or anti-thymocyte globulin), infections (bacterial, viral, fungal and protozoal), cytomegalovirus (CMV) status, CMV mismatch, diabetes mellitus, hypertension and incidence of rejection episodes and transplant coronary artery disease within 2 years of HTx. RESULTS: Group A (135 men, 23 women; mean age 48 +/- 11 years) had significantly fewer post-HTx rejection episodes and viral, bacterial, fungal and total infections than did Group B (95 men, 21 women; mean age 49 +/- 12 years). Group A also had a significantly lower mean donor age, a lower incidence of pre-HTx diabetes, and a lower mean cholesterol level 1 year after HTx. In a multivariate analysis, fewer bacterial infections and rejection episodes after HTx, the absence of pre-HTx diabetes, and lower donor age were associated with longer survival. CONCLUSIONS: Pre-HTx diabetes, donor age and incidences of infection and rejection within 2 years of HTx predict long-term (>10-year) survival. Better control of infection and rejection during the first 2 years after HTx may improve survival.

Age Factors↗
PubMed2005

Isolated ventricular non-compaction in adults with idiopathic cardiomyopathy: cardiac magnetic resonance and pathologic characterization of the anomaly.

Non-compaction of the ventricular myocardium is an anomaly of myocardial morphogenesis that leads to persistence of the embryonic myocardium with an excessively prominent trabecular meshwork and deep intertrabecular recesses. This report describes 3 cases of isolated left ventricular non-compaction in adults leading to terminal heart failure. We describe their distinctive myocardial histopathology and prospective diagnosis by cardiac magnetic resonance imaging (CMR). Heart transplantation was the only treatment option for all 3 of these severely ill patients. Isolated ventricular non-compaction should be considered in patients with severe idiopathic cardiomyopathy whose symptoms appear in early adulthood, and consideration given for early transplantation. Non-invasive imaging with CMR can confirm the diagnosis.

Adult↗
PubMed2005

Alterations in alpha adrenoreceptor density and localization after mechanical left ventricular unloading with the Jarvik flowmaker left ventricular assist device.

Cardiac alpha one adrenoreceptors (alpha(1)AR) are known to mediate positive inotropism in human ventricular myocardium. In the early stages of heart failure, ventricular contractility is maintained by adrenergic stimulation, rennin-angiotensin activation, and other neurohormonal and cytokine system responses. As the disease progresses, however, these compensatory mechanisms cease to provide benefit; ventricular dilation and fibrosis occur and cardiac function deteriorates. When ventricular contractility becomes severely depressed and is no longer responsive to inotropic support, insertion of a left ventricular assist device (LVAD) may allow the left ventricle to rest, remodel, and recover some contractile function. Our previous work has demonstrated that the myocardium has the capacity to repair itself during a period of unloading, after which some patients are able to resume a normal lifestyle and no longer need a cardiac transplant.

Aged↗
PubMed2005

Is bridging to transplantation with a left ventricular assist device a risk factor for transplant coronary artery disease?

BACKGROUND: Left ventricular assist device (LVAD) support is associated with coagulopathy, bleeding, increased blood transfusion, and increased anti-HLA antibody production. Increased anti-HLA antibody production is associated with early transplant rejection, transplant coronary artery disease (CAD), and decreased post-transplant survival rates. We asked whether bridging to transplantation with an LVAD increases the risk of transplant CAD. METHODS: We reviewed data for all adults (>18 years old) who underwent heart transplantation at our institution between 1988 and 2000. After exclusion of transplant recipients who survived <3 years, we divided the remaining cohort into 2 groups: those bridged to transplantation with LVADs (mean duration of support, 149 +/- 107 days, n = 29) and those in United Network for Organ Sharing Status 1 bridged to transplantation without LVADs (controls, n = 86). We compared groups in terms of disease cause, age, sex, donor age, panel-reactive antibody testing, crossmatching, pre- and post-transplant cholesterol concentrations, diagnosis of diabetes mellitus or treated hypertension, infections, calcium channel blocker use, transplant rejection, ischemic time, cytomegalovirus infection, pre-transplant transfusion, and incidence of transplant CAD (defined as any coronary lesion identified by coronary angiography). We considered p < 0.05 to be significant. RESULTS: The bridged and control groups were similar in all respects except mean ischemic time (217 +/- 58 minutes vs 179 +/- 67 minutes, p = 0.007), post-transplant cholesterol concentration (212 +/- 55 mg/dl vs 171 +/- 66 mg/dl, p = 0.007), and pre-transplant transfusion incidence (100% vs 22%, p < 0.001). The incidence of transplant CAD was similar in both groups during a 3-year follow-up period (28% vs 17%, p = 0.238) and during total follow-up (34% vs 35%, p = 0.969). Multivariate logistic regression analysis identified cholesterol concentration at 1 year after transplantation as a significant predictor of CAD at 3 years after heart transplantation (p = 0.0029, odds ratio = 0.984). CONCLUSIONS: Bridging to transplantation with an LVAD does not increase the risk of transplant CAD. Nevertheless, aggressive prophylactic therapy to minimize potential risk factors for transplant CAD, such as increased cholesterol concentration, is warranted in all transplant recipients.

Adult↗
PubMed2005

Nitric oxide versus prostaglandin E1 for reduction of pulmonary hypertension in heart transplant candidates.

BACKGROUND: We sought to directly compare the effects of prostaglandin E1 (PGE1) and nitric oxide (NO) in testing for pulmonary hypertension reversibility in heart transplant candidates. METHODS: We included 19 heart transplant candidates who fulfilled at least 1 of 3 criteria: pulmonary vascular resistance (PVR) of >4 Wood units; transpulmonary gradient (TPG) of >12 mmHg; or systolic pulmonary artery pressure (PAP) of >60 mmHg. Patients randomly received either PGE1 (0.05, 0.2 and 0.5 microg/kg/min) or NO (40, 60 and 80 ppm) and were crossed-over to the second medication after receiving the maximal dose of the first. RESULTS: With PGE1, TPG decreased by 21% (baseline 20.3 +/- 6.8 mmHg; final 16.0 +/- 7.0 mmHg) compared to a 34% decrease with NO (baseline 20.8 +/- 6.2 mmHg; final 13.8 +/- 5.4 mmHg) (p = 0.13). PVR decreased by 42% with PGE1 (baseline 6.2 +/- 4.0 Wood units; final 3.6 +/- 1.8 Wood units) and by 47% with NO (baseline 6.0 +/- 3.9 Wood units; final 3.2 +/- 1.6 Wood units) (p = 0.87). Mean systemic pressure decreased with PGE1 (baseline 76.1 +/- 10.5 mmHg; final 69.4 +/- 12.2 mmHg; -9%) but not with NO administration (baseline 70.2 +/- 14.7 mmHg; final 71.6 +/- 10.9 mmHg; +2%) (p = 0.01). TPG was lowered to <12 mmHg in 14 patients. Of these, 6 (46%) responded to both PGE1 and NO, 4 (27%) responded only to PGE1, and 4 (27%) responded only to NO. CONCLUSIONS: The effects of PGE1 and NO on pulmonary hypertension are comparable, with PGE1 having more systemic hypotensive effects. Due to variability of patient responses, we recommend multiple rather than single-agent pharmacologic testing for the reversibility of pulmonary hypertension.

Administration, Inhalation↗
PubMed2005

Post-operative obesity and cachexia are risk factors for morbidity and mortality after heart transplant: multi-institutional study of post-operative weight change.

BACKGROUND: The relationship between post-heart transplant cachexia and obesity with subsequent morbidity and mortality has not yet been reported. Therefore, the purposes of this study were to: (1) describe change in body mass index (BMI) from before transplant through 5 years after transplant; (2) identify risk factors for increased BMI at 1 year post-transplant; and (3) determine whether post-transplant BMI is associated with post-transplant morbidity and mortality. METHODS: Patients (n = 3,540) were from a non-random sample having received a heart transplant between January 1, 1996 and December 31, 2001 at 33 institutions of the Cardiac Transplant Research Database (CTRD). Patients were divided into groups using cut-offs for categories of BMI. Data were assessed according to frequencies, measures of central tendency, Pearson correlations, chi-square tests, multiple regression and stratified actuarial analyses with log-rank tests for comparisons. The level of statistical significance was set at p = 0.05. RESULTS: The number of obese patients increased significantly from immediately before heart transplant to 5 years later (17% vs 38%) (p < 0.0001). Risk factors for increased BMI at 1 year after heart transplant (explaining 56% of variance) included increased BMI at transplant, younger age, black race, non-ischemic etiology of heart disease, Status I at time of transplant and non-use of mycophenolate mofetil. Patients who were underweight or obese at 1 year post-transplant were at greater risk for rejection over time than patients who were of normal weight or overweight (p = 0.009). CONCLUSIONS: Both demographic and clinical factors are related to increased BMI at 1 year after heart transplantation. Post-transplant cachexia and obesity are risk factors for poor clinical outcomes after heart transplantation.

Adolescent↗
PubMed2005

Antiphospholipid syndrome with anti-prothrombin autoantibodies in a patient with an axial-flow left ventricular assist device.

Autoantibodies to prothrombin, first described almost 50 years ago, are paradoxically associated with thrombosis. Described is an unusual case of fatal hypercoagulability in a patient with multiple arterial and venous thromboembolic complications despite intense anticoagulation while being bridged to transplantation with a left ventricular assist device. Serum analysis revealed the presence of prothrombin autoantibodies and high titers of anti-nuclear antibodies, and autopsy revealed pulmonary arteriolar vasculitis. These findings suggest an autoimmune basis for the presence of anti-prothrombin antibodies and the hypercoagulable state observed in the present case.

Antibodies, Antiphospholipid↗
PubMed2005

Survival, graft atherosclerosis, and rejection incidence in heart transplant recipients treated with statins: 5-year follow-up.

BACKGROUND: Few studies have examined the long-term benefits of statin treatment in heart transplant recipients. METHODS: In this observational study, we retrospectively reviewed data pertaining to 5-year follow-up of patients who underwent heart transplantation between 1993 and 1996 and who survived the first 30 days after transplantation. Patients were assigned to groups according to whether or not they received pravastatin after transplantation, and then compared with regard to transplant rejection, transplant coronary artery disease, and survival. RESULTS: Ninety-one patients received pravastatin after transplantation, whereas 37 did not receive any statins and served as controls. Pravastatin did not affect the overall incidence of rejections or number of rejection episodes. Hemodynamically significant rejection episodes occurred in 5 patients (5%) in the pravastatin group and 4 patients (11%) in the control group. Thus, pravastatin treatment apparently reduced the incidence of hemodynamically significant rejection episodes by 50% (p = 0.04). Transplant coronary artery disease (CAD) occurred in 10 patients (11%) in the pravastatin group and 9 patients (24%) in the control group. Treatment with pravastatin significantly reduced the incidence of transplant CAD (p = 0.05). Three- and 5-year survival rates in the pravastatin group were significantly better than in the control group (87% vs 68% and 82% vs 58%, respectively; p = 0.009). CONCLUSIONS: Pravastatin therapy offers long-term benefits to heart transplant recipients. It improves 5-year survival, lowers the risk of transplant CAD, and lowers the incidence of hemodynamically significant rejection episodes.

Adolescent↗
PubMed2005

Role of B-type natriuretic peptide and effect of nesiritide after total cardiac replacement with the AbioCor total artificial heart.

Endogenous B-type natriuretic peptide (BNP) is thought to be produced in the cardiac ventricles. After sub-total cardiectomy and implantation of a total artificial heart (TAH), the abrupt withdrawal of BNP impairs renal function despite normal hemodynamic variables. We hypothesized that abrupt withdrawal of endogenous BNP may impair renal function and volume homeostasis and BNP may have a direct renal influence unrelated to its cardiovascular effect. Nesiritide infusion should be supplemented in the interim and weaned slowly until BNP levels normalize, which suggests that BNP is produced in tissues other than the cardiac ventricles.

Acute Kidney Injury↗
PubMed2005

Percutaneous tracheostomy after mechanical ventricular assist device implantation.

BACKGROUND: Several studies have shown that percutaneous dilational tracheostomy (PDT) is safe and cost-effective for patients recovering from surgery that requires a median sternotomy. We report our experience with PDT in patients receiving mechanical cardiac assistance. METHODS: We reviewed the medical records of all patients who underwent ventricular assist device implantation at our institution between July 2000 and July 2003, and who subsequently required long-term ventilatory support during the same hospital admission. Data obtained from the records included demographic and biometric information, primary diagnosis, early (< or =30days) and late (>30days) complications, date and cause of death, type of anti-coagulation used at the time of tracheostomy, and various coagulation measures. RESULTS: Thirty-one consecutive patients (29 men, 2 women; mean age, 56 years) had PDT after ventricular assist device implantation. Four minor complications occurred among 3 of the patients (10%), including 3 early complications (2 peristomal oozing and 1 peristomal cellulitis) and 1 late complication (recurrent peristomal cellulitis), none of which affected long-term outcome. No major adverse events, long-term complications, or deaths resulted from the PDT procedure. CONCLUSIONS: PDT is feasible for patients with mechanical support devices who require long-term ventilatory support. Although some of these patients are coagulopathic, our results indicate that PDT is safe and effective in this challenging patient population.

Female↗
PubMed2005

Brachiocephalic reconstruction II: operative and endovascular management of single-vessel disease.

OBJECTIVE: Although the surgical management of brachiocephalic disease is well established, evolving endovascular techniques present new options for treatment. We explored the potential benefits and drawbacks of these interventions in terms of outcome. METHODS: From 1966 to 2004, 391 consecutive patients (43.7% male; mean age, 61.9 years) with single-vessel brachiocephalic disease were treated with either operative bypass (group A; n = 229) or percutaneous transluminal angioplasty and stenting (group B; n = 162). RESULTS: All patients were asymptomatic after surgery or endovascular intervention. Group A and group B had similar operative mortality (0.9% vs 0.6%) and stroke (1.3% vs 0%) rates. However, 5 years after the procedure, group A had significantly better freedom from graft or intervention failure (92.7% +/- 2.1%) than did group B (83.9% +/- 3.7%; P = .03, Kaplan-Meier analysis; P = .001, Cox regression analysis). At 10 years, group A had the following rates of actuarial freedom from specific events: death, 73.7% +/- 4.6%; myocardial infarction, 84.2% +/- 3.6%; stroke, 91.4% +/- 3.4%; graft failure, 88.1% +/- 3.3%; coronary revascularization, 69.8% +/- 5.1%; and other vascular operation, 70.7% +/- 4.6%. Endovascular intervention involved less initial cost (mean savings, $8787 per procedure), was less invasive, and did not necessitate general anesthesia. On satisfaction questionnaires, 96.5% of patients receiving an endovascular intervention and 95.1% of patients receiving operative bypass for single-vessel brachiocephalic disease subjectively rated their treatment as "good" or "very good." CONCLUSIONS: Operative bypass and endovascular intervention for single-vessel brachiocephalic disease are both associated with acceptably low operative morbidity and mortality. Operative bypass produces significantly better mid-term freedom from graft or intervention failure than endovascular intervention and produces excellent long-term freedom from failure. Endovascular intervention offers tangible benefits regarding cost, level of invasiveness, and subjective patient satisfaction. Undetermined are the differences between the procedures regarding long-term durability, patterns of failure, efficacy as an adjunct to coronary artery bypass grafting, need for anticoagulation, efficacy as treatment for complex (multivessel) disease, and long-term cost.

Adult↗
PubMed2005

Brachiocephalic reconstruction I: operative and long-term results for complex disease.

OBJECTIVES: Complex brachiocephalic disease involves multiple vessels and is frequently associated with multisystem atherosclerosis. We reviewed surgical outcome and examined the impact of this problem on decision making regarding operative staging, technique, and choice of conduit. METHODS: Between 1966 and 2000, 157 consecutive patients (mean age, 54.0 years; 48.4% male) with innominate artery or multivessel brachiocephalic disease underwent operative reconstruction using either a transthoracic approach (group A, n = 113) or a less invasive, extrathoracic approach (group B, n = 44). Reconstruction required multiple distal anastomoses in 70 patients (44.6%), concomitant coronary artery bypass grafting (CABG) in 37 patients (23.6%), and concomitant carotid endarterectomy (CEA) in 26 patients (16.6%). RESULTS: No significant differences were found between group A and group B when operative mortality (2.7% vs 2.3%) and stroke rates (2.7% vs 6.8%) were analyzed. However, 10 years after surgery, freedom from graft failure was significantly better in group A (94.4% +/- 4.4%) than in group B (60.3% +/- 13.4%) ( P = .002). Freedom from graft failure was adversely affected by nonaortic inflow ( P = .002) and axillo-axillary cervical grafts ( P = .0001). Mortality and stroke rates for subgroups having multiple distal anastomoses (2.9%, 2/70 and 4.3%, 3/70), concomitant CABG (5.4%, 2/37 and 0, 0/37), and concomitant CEA (3.8%, 1/26 and 3.8%, 1/26) were similar to those of other patients. For the entire patient group, 10-year rates of actuarial freedom from specific events were death, 68.8% +/- 6.0%; myocardial infarction, 86.7% +/- 4.5%; stroke, 87.0% +/- 4.4%; coronary revascularization, 88.0% +/- 3.6%, and other vascular operation, 79.9% +/- 4.4%. CONCLUSIONS: Transthoracic arch reconstruction for complex brachiocephalic disease can be done with acceptably low morbidity and mortality similar to those of a less invasive, extrathoracic approach. Furthermore, the transthoracic approach is associated with significantly better long-term freedom from graft failure, possibly because it preserves aortic inflow to the great vessels. Nonetheless, the high frequency of late events in this relatively young patient population reflects the presence of multisystem atherosclerosis and suggests the need for close follow-up and lifestyle modification.

Adult↗
PubMed2005

Thirty-five years of mechanical circulatory support at the Texas Heart Institute: an updated overview.

Since the 1960s, the Texas Heart Institute has been intimately involved in the development of mechanical circulatory support devices (for example, ventricular assist devices, aortic counterpulsation pumps, and total artificial hearts) for both short- and long-term use. Here, we review the varied clinical experience with these technologies at the Texas Heart Institute over the last 35 years.

Assisted Circulation↗
PubMed2005

Pulmonary microthrombi during left ventricular assist device implantation.

Critically ill heart failure patients undergoing left ventricular assist device implantation have alterations in their coagulation profiles; as a result, hemorrhagic complications during the postoperative period are the most common and serious problems during device support of these patients. The use of aprotinin therapy is generally accepted for reducing bleeding after coronary artery bypass grafting procedures, heart transplantation, and insertion of a left ventricular assist device. We describe the case of a patient who had a suprasystemic increase in pulmonary artery pressure, caused by thromboembolic occlusion of the pulmonary arterioles after urgent implantation of a left ventricular assist device. The complications developed after the patient was weaned from cardiopulmonary bypass and heparinization was reversed with protamine. Although the thrombosis was successfully reversed with intraoperative administration of tissue plasminogen activator directly to the pulmonary artery, the patient died of massive hemorrhage 6 hours later. To our knowledge, the direct application of tissue plasminogen activator into the pulmonary artery in such a catastrophic situation has not been used elsewhere.

Blood Coagulation↗
PubMed2005

Echocardiographic evaluation of the Jarvik 2000 axial-flow LVAD.

From April 2000 through September 2001, we studied 11 patients with the Jarvik 2000--a left ventricular assist device with an axial-flow pump that provides continuous blood flow--to determine the echocardiographic characteristics. All patients underwent complete echocardiographic examination, including outflow-graft flow evaluation 24 hours after implantation and each month thereafter for the duration of support. Data were obtained at each pump setting (8000-12000 rpm in 1000-rpm increments) and with the pump off. Left ventricular dimensions and shortening fraction and the duration of aortic valve systolic opening decreased as pump speed increased. Although the aortic valve remained closed at higher pump speeds, pump outflow-graft flow remained pulsatile, because of the systolic thrust of the assisted ventricle. Systolic dominance of phasic flow was more pronounced at lower pump speeds, due to normalization of the diseased heart's Starling response. When the aortic valve was closed continuously, echocardiographic contrast (indicating blood stasis) was noted in the aortic root. Because of the pump outflow graft's proximity to the chest wall, device output could be measured independently of cardiac contributions. Mean peak outflow-graft flow velocities were 0.75 +/- 0.30 m/s (systolic) and 0.41 +/- 0. 13 m/s (diastolic). When the pump was turned off briefly there was minimal regurgitation through the device into the left ventricle. This 1st echocardiographic heart function analysis of the Jarvik 2000 confirms that the device unloads the ventricle and increases cardiac output. Cardiac responses to device-speed changes can be evaluated readily with echocardiography in the early and late postoperative period.

Blood Flow Velocity↗
PubMed2005

The effect of LVAD aortic outflow-graft placement on hemodynamics and flow: Implantation technique and computer flow modeling.

Axial-flow ventricular assist devices (VADs) can be implanted either through a left thoracotomy with outflow-graft anastomosis to the descending thoracic aorta or through a midline sternotomy with anastomosis to the ascending aorta. Each method has advantages and disadvantages. Because these VADs produce nonpulsatile flow, their hemodynamic characteristics differ from those of pulsatile devices. These differences may have important clinical consequences, particularly in relation to the outflow-graft configuration. We describe a computer-generated flow model that we created to illustrate the flow dynamics and possible clinical consequences of each method. The simulations indicate that the location of the anastomosis has important qualitative effects on flow in the ascending aorta and aortic arch. At high VAD outputs (> or =75%), native cardiac output cannot supply the carotid and subclavian arteries. With a descending aortic anastomosis, net backward flow occurs in the descending aorta to supply these branches. Consequently, the aortic arch has a region with almost no net flow, where fluid particles stagnate over many cardiac cycles, possibly causing thrombogenesis. With an ascending aortic anastomosis, the arch has no stagnant region, although flow turbulence still occurs. When the aortic valve remains closed, so that the total output occurs through the VAD, the aortic root has a region of nearly stagnant flow. With an ascending aortic anastomosis, a small degree of recirculatory flow may prevent complete stagnation at the aortic root. With the descending aortic anastomosis, however, no recirculation occurs. These results help delineate the complex flow dynamics and the advantages and drawbacks of each technique.

Aortic Valve↗