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Biomedical subjects

O H Frazier

Publications and source records attributed to O H Frazier.

At least 181 records · Page 10Linked to original sources
PubMed1997

Mechanical support in dilated cardiomyopathy: signs of early left ventricular recovery.

BACKGROUND: Recent reports have documented left ventricular recovery in patients with dilated cardiomyopathy off-loaded long term with a left ventricular assist device. We sought to document the natural history of left ventricular recovery. METHODS: We implanted the TCI left ventricular assist device without the intention to perform transplantation in 2 patients with dilated cardiomyopathy who had been rejected for transplantation. Both were in New York Heart Association functional class IV and had renal failure. One was a diabetic. We studied left ventricular function with detailed echocardiography at 4, 6, and 8 weeks postoperatively. RESULTS: With the left ventricular assist device turned off, we observed a progressive increase in myocardial contractility beginning as early as 4 weeks after implantation and improving progressively. Histologic examination showed resolution of myocytolysis in both patients. CONCLUSIONS: Left ventricular recovery begins earlier than was previously suspected. Mechanical bridge to myocardial recovery is a potential approach to therapy for such patients.

Cardiomyopathy, Dilated↗
PubMed1997

Transmyocardial laser revascularization: results of a multicenter trial with transmyocardial laser revascularization used as sole therapy for end-stage coronary artery disease.

BACKGROUND: Transmyocardial laser revascularization was used as the sole therapy for patients with ischemic heart disease not amenable to percutaneous transluminal coronary angioplasty or coronary artery bypass grafting. This technique uses a carbon dioxide laser to create transmyocardial channels for direct perfusion of the ischemic heart. METHODS: Since 1992, 200 patients, at eight hospitals in the United States, have undergone transmyocardial laser revascularization. The patients have a combined 1560 months of follow-up for an average of 10 +/- 3 months per patient. Their age was 63 +/- 10 years and their ejection fraction was 47% +/- 12%. Eighty-two percent had at least one previous bypass graft operation and 38% had a prior angioplasty. Preoperatively, the patients underwent nuclear single photon emission computed tomography perfusion scans to identify the extent and severity of their ischemia. These scans were repeated at 3, 6, and 12 months. Angina class, admissions for angina, and medications were recorded. RESULTS: The perioperative mortality was 9%. Angina class decreased significantly from before treatment to 3, 6, and 12 months (p < 0.001). Likewise, there was a significant decrease in the number of perfusion defects in the treated left ventricular free wall. Concomitantly, there was a significant decrease in the number of admissions for angina in the year after the procedure when compared with the year before treatment (2.5 vs 0.5 admissions per patient-year). CONCLUSION: These combined results indicate that transmyocardial laser revascularization provides angina relief, decreases hospital admissions, and improves perfusion in patients with severe coronary artery disease.

Adult↗
PubMed1997

Revascularization procedures in patients with transplant coronary artery disease.

OBJECTIVE: To assess the efficacy of revascularization in cardiac transplant patients who developed de novo coronary artery disease. METHODS: Eighteen patients underwent one or more of four methods of revascularization: percutaneous transluminal coronary angioplasty (PTCA), percutaneous transluminal coronary rotational atherectomy (PTCRA), coronary artery bypass grafting (CABG), and transmyocardial laser revacularization (TMLR). Eleven PTCA procedures were performed in 10 patients 55.3 +/- 6.6 months after transplantation. Six patients underwent PTCRA 83.3 +/- 11.2 months after transplantation. Five patients underwent CABG 54.0 +/- 12.6 months after transplantation; the mean left ventricular ejection fraction was 49.6 +/- 16.9 (20-65%); hypertrophy was present in two of these patients. One patient with distal coronary artery disease and New York Heart Association class IV symptoms underwent TMLR only. One patient underwent both CABG and TMLR because of triple vessel proximal disease, diffuse distal disease, and New York Heart Association class IV symptoms. RESULTS: PTCA was successful in 10 procedures with decrease in mean stenosis from 87.7 +/- 2.7 to 24.3 +/- 6.0%. Follow-up, at 16.9 +/- 4.0 months, showed restenosis in two patients. PTCRA was successful in all patients with a decrease in mean stenosis from 83.4 +/- 4.4 to 11.7 +/- 1.9%. Short-term follow-up did not reveal reocclusion. Two CABG patients who had hypertrophy died of heart failure 2 and 9 days after their operations. One CABG patient with excellent cardiac function died after 15 days because of pulmonary failure. In one patient, left ventricular ejection fraction improved from 35 to 50%, and he is alive 64 months later. Six months after TMLR, the New York Heart Association class in one patient improved from IV to II, and his left ventricular ejection fraction improved from 29 to 42%. The ejection fraction in the patient who underwent both CABG and TMLR improved from 20 to 56% but the patient expired 7 weeks later. CONCLUSIONS: It appears that revascularization procedures can be effective in patients with coronary artery disease after cardiac transplantation and that coronary angioplasty or atherectomy would be a therapy of choice for single proximal lesions. CABG should be used cautiously and only reserved for patients with multi-vessel disease without hypertrophy. Laser revascularization with or without bypass grafting has potential to become the therapy of choice for transplant coronary artery disease.

Angioplasty, Balloon, Coronary↗
PubMed1997

The development, evolution, and clinical utilization of artificial heart technology.

The ventricular assist device has evolved into an effective clinical tool to treat patients with severe heart failure. Left ventricular assist systems, such as the HeartMate, have demonstrated their utility as short- and long-term bridges to heart transplantation and their ability to effect a degree of ventricular recovery in some patients. These devices will soon be used more commonly as an alternative to transplantation.

Biocompatible Materials↗
PubMed1996

Sudden cardiac death in cardiac transplant recipients.

BACKGROUND: Sudden cardiac death (SCD) remains a significant cause of mortality in the general population. Its role in cardiac transplant patients-including its incidence, mechanism, potential risk factors, or influence on survival in this patient population-has not been well described. METHODS AND RESULTS: We undertook a retrospective analysis of the clinical and autopsy records of 257 patient deaths. SCD was analyzed in relation to severity and frequency of rejection episodes, clinical history of arrhythmias, coronary artery disease (CAD), hypertension, diabetes, left ventricular dysfunction, and clinical history of premorbid symptoms. A total of 25 patients were identified as having died of SCD, an incidence of 9.7%: 20% died < or = 12 months after transplantation, 80% died after > 12 months, and 20% died after > or = 60 months. Patient survival ranged from 2.5 to 138 months (mean, 45.7 months). The mean number of rejection episodes per patient was 2.6, most occurring within 12 months after transplantation. Echocardiography or multigated acquisition scan revealed an ejection fraction (EF) > or = 50% in 68% of patients; however, the presence of arrhythmias, primarily atrial, was evident in 68% of patients and was equally distributed between patients with EFs > or = 50% and EFs < 50%. CAD was present in 53% of patients (10 of 19) whose angiograms were available, and the appearance of CAD after transplantation was between 29 and 85 months (mean, 51.4 months). Of the 9 patients with normal cardiac catheterization studies, 6 with available autopsy reports had documented CAD. Autopsy data in 13 of 25 patients revealed CAD in 92% and rejection in 15% (International Society for Heart and Lung Transplantation grade > 3A). Of the deaths, 64% occurred within 3 months of the last endomyocardial biopsy, 96% had normal biopsies, and the only rejection was without hemodynamic compromise. CONCLUSIONS: SCD occurs relatively frequently in the cardiac transplant population, and CAD is present in most of the patients. Because the frequency of arrhythmias is relatively high in this group, more aggressive antiarrhythmic therapy may be beneficial for patients with allograft CAD in the prevention of SCD.

Adult↗
PubMed1996

The paradox of cytokine monitoring-predictor of immunologic activity as well as immunologic silence following cardiac transplantation.

The utility of cytokine monitoring to predict the onset of significant rejection was evaluated in 34 patients following heart transplantation. Serial blood levels of 5 cytokines involved in inflammation and immune activation(IL-1, IL-2, IL-6, IL-8, and TNF) were correlated with clinical outcome and endomyocardial biopsy scores. The majority of patients (68%) experienced a significant rejection during the study period. IL-6 and IL-8 levels were effective markers of significant rejection 2-4 days before diagnosis with EMBX. IL-6 and IL-8 levels of 15 and 1000 pg/ml predicted the onset of rejection with sensitivities of 75% and 66% and specificities of 86% and 76%, respectively. In contrast, IL-6 and IL-8 levels less than 15 and 400 pg/ml predicted a rejection-free course with sensitivities of 91% and 91% and specificities of 81% and 68%, respectively. The remaining cytokines differentiated patients experiencing a clinically unremarkable course from those experiencing mild-to-moderate rejection but did not discriminate rejection severity. IL-6 levels identified steroid and OKT3 resistance within 48 hr of antirejection therapy. IL-6 levels elevated to 197 +/- 20 pg/ml among steroid-resistant patients and normalized to 20 +/- 5 pg/ml among responders. IL-8 levels delineated OKT3 resistance. IL-8 levels rose to 3496 +/- 500 pg/ml among nonresponders, whereas levels fell to 152 +/- 50 pg/ml among responders. This study demonstrates that IL-6 and IL-8 are useful markers of rejection and therapeutic efficacy following heart transplation.

Adult↗
PubMed1996

Evolution of battery-powdered, vented left ventricular assist devices.

Battery-powered, vented left ventricular assist devices are designed to provide long-term circulatory support and an enhanced qualify of life. Their ongoing evolution into an effective clinical tool to treat patients with severe heart failure has resulted from the efforts of many, the open communication among researchers involved in the program, and the strong support from the National Institutes of Health.

Equipment Design↗
PubMed1996

Surgical treatment of multiple coronary aneurysms in an elderly man.

We report an unusual case involving a 70-year-old man with multiple coronary aneurysms, including a 5-cm aneurysm of the right coronary artery. The precise size was determined with magnetic resonance imaging, although the aneurysms were diagnosed initially on angiography. Multiple coronary aneurysms are rare in adults, The cause may have been atherosclerosis, syphilis, or collagen vascular disease, all of which cause weakening of the media. The patient underwent successful operation, including coronary artery bypass grafting.

Aged↗
PubMed1996

Complete resection of a right atrial intracavitary metastatic melanoma.

We report a case of complete resection of a very large intracavitary metastatic melanoma of the right atrium. We describe a technique for resecting without damaging the atrium and for preventing the narrowing of the right atrium. In such cases, complete resection may be indicated despite widespread disease.

Female↗
PubMed1996

Low thromboembolic risk without anticoagulation using advanced-design left ventricular assist devices.

BACKGROUND: A major limitation of cardiac assist devices has been the high incidence of thromboembolic events and their requirement for systemic anticoagulation. The Thermo Cardiosystems HeartMate 1000 IP left ventricular assist device (LVAD) employs a design that may reduce thromboembolic risk and obviate the need for systemic anticoagulation. METHODS: Two hundred twenty-three patients with nonreversible heart failure were supported with the HeartMate LVAD as a bridge to heart transplantation. All patients were monitored prospectively for thromboembolic events. Anticoagulation regimens and occurrence of subclinical thromboembolic events, including those seen by transcranial Doppler examinations in selected patients, were also recorded. RESULTS: Total time of LVAD support use was 531.2 patient-months. Twenty-three patients (10%) received warfarin postoperatively for 42.4 patient-months (8.2% of total support time). Six patients (2.7%) had thromboembolic events, representing 0.011 events per patient-month of device use. CONCLUSIONS: The thromboembolic complication rate associated with this LVAD is acceptably low despite the minimal anticoagulation employed in this series, allowing consideration of long-term device use for the treatment of heart failure.

Adolescent↗
PubMed1996

Improved left ventricular function after chronic left ventricular unloading.

BACKGROUND: This study assessed the effect of prolonged left ventricular unloading on native ventricular function. METHODS: We reviewed data from 31 patients (30 men, 1 woman) supported more than 30 days (mean, 137 days; range, 31 to 505 days) with the HeartMate left ventricular assist system. The patients' mean age was 46 years (range, 22 to 64 years); 17 had idiopathic and 14 had ischemic cardiomyopathy. Data (anatomic, physiologic, hemodynamic, histologic, and biochemical) were collected at the time of HeartMate implantation, during support with the device temporarily off, and at the time of device explantation. RESULTS: Routine chest roentgenogram showed improvement in cardiothoracic ratio (0.62 +/- 0.04 to 0.55 +/- 0.03; p < 0.0001). Echocardiography performed with the pump off showed a significant decrease in left ventricular end-diastolic dimension (6.81 +/- 0.87 cm to 5.39 +/- 1.08 cm; p < 0.0005) and a significant improvement in ejection fraction (0.11 +/- 0.05 to 0.22 +/- 0.17; p < 0.02). Cardiac index increased (1.96 +/- 0.52 L.min-1.m-2 to 2.93 +/- 0.73 L.min-1.m-2; p < 0.0001), mean aortic pressure increased (71.40 +/- 10.63 mm Hg to 76.33 +/- 16.84 mm Hg; p = 0.48), pulmonary capillary wedge pressure decreased (24.18 +/- 6.27 mm Hg to 14.48 +/- 3.01 mm Hg; p < 0.0001), and pulmonary vascular resistance decreased (3.34 +/- 2.00 Wood units to 2.51 +/- 0.88 Wood units; p < 0.05). Comparisons of tissue samples taken at the time of implantation and at the time of transplantation showed a marked reduction in myocytolysis. Calcium uptake, calcium-binding rates, and lipid levels normalized in patients studied. Plasma norepinephrine levels decreased to near normal levels. CONCLUSION: Prospective studies are now indicated to determine whether device removal without transplantation may be beneficial in selected patients.

Adult↗
PubMed1996

Transmyocardial laser revascularization: clinical experience with twelve-month follow-up.

We are investigating a new technique for myocardial revascularization in which an 800 W carbon dioxide laser is used to drill 1 mm diameter channels into a beating heart after left thoracotomy. Clotting occludes the channels on the subepicardium, and in the long-term setting, blood from the left ventricular cavity flows through these channels to perfuse the ischemic subendocardium. To test the efficacy of this technique in a preliminary clinical trial, we used it as sole therapy for 21 consecutive patients. All patients had hibernating myocardium, reduced coronary flow reserve, or both, had distal diffuse coronary artery disease, and had angina refractory to normal therapy. Eight patients were excluded from follow-up because of death (n=5), rerevascularization (n=2), or diaphragmatic paralysis resulting in postoperative respiratory incapacity (n=1). In the remaining 13 patients available for follow-up, the mean angina class (Canadian Cardiovascular Society) was 3.7 +/- 0.4 before operation and 1.8 +/- 0.6 12 months after operation (p < 0.01). Mean resting left ventricular ejection fraction was 48% +/- 10% before operation and 50% +/- 8% at 12-month follow-up. At 12 months, resting mean subendocardial/subepicardial perfusion ratio had increased by 20% +/- 9% in septal regions treated by laser but decreased by 2% +/- 5% in untreated regions (n=11, p <.001). These results suggest that revascularization by this laser technique positively affects subregional myocardial perfusion and may result in clinical benefits for patients with reversible myocardial ischemia. Studies to date have not demonstrated significant changes in global and regional ventricular contractile function.

Aged↗
PubMed1996

Transmyocardial laser revascularization.

Transmyocardial laser revascularization is currently being tested in randomized clinical trials as an alternative technique for relieving angina in patients with ischemic myocardium. In this technique, an 800-W carbon dioxide laser is used to create channels in the myocardium that open directly into the left ventricular cavity. Although the exact mechanism by which tissue revascularization occurs is not yet known, initial results from an earlier clinical trial were promising: a significant number of patients were relieved of angina symptoms, exercise tolerance was improved, complications were minimal, and the safety of the technique seems established. A controlled, randomized trial is now underway, and initial results appear promising.

Female↗
PubMed1996

Cardiac devices.

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Animals↗
PubMed1996

Increased expression of ICAM-1 in a case of accelerated coronary artery disease after heart transplantation.

The development of accelerated coronary artery disease after heart transplantation remains the limiting factor for long-term survival. The most widely accepted hypothesis to explain the development of this vascular lesion is chronic immunologic injury to the vessel wall, which leads to recruitment of monocytes and lymphocytes into the intima and to subsequent neointimal proliferation. In this report, we describe a case of accelerated coronary artery disease that led to allograft failure and repeat heart transplantation 3 years after the initial procedure. Pathologic examination showed striking intimal proliferation with abundant expression of intercellular adhesion molecule-1 in both endothelial cells and cells deep within the intima. Cardiac myocytes also stained for intercellular adhesion molecule-1, with the most intense staining noted in intercalated disks, whereas staining for E-selectin was restricted to endothelial cells. These findings are similar to those we observed in a canine model of transplant arteriopathy and highlight the need for further studies to examine whether inhibitors of endothelial cell adhesion molecules or their leukocyte ligands can successfully ameliorate transplant vasculopathy.

Coronary Disease↗