Biomedical subjects

R T Baldwin

Publications and source records attributed to R T Baldwin.

At least 19 recordsLinked to original sources

PubMed1996

Complicated right subclavian artery pseudoaneurysm after central venipuncture.

Life-threatening complications of central venipuncture are rare. We report an unusual case of a patient in whom a large right subclavian pseudoaneurysm developed, causing pressure necrosis of the membranous trachea and esophagus, after right internal jugular vein cannulation. The patient underwent oversewing of the proximal and distal ends of the subclavian artery and primary tracheal repair. An esophageal leak that presented on the sixth postoperative day was treated by primary suture repair with proximal and distal diversion.

Aged↗

PubMed1993

A model to predict survival at time of postcardiotomy intraaortic balloon pump insertion.

To facilitate timely application of new forms of cardiac support to patients at highest risk after cardiotomy despite conventional support with the intraaortic balloon pump, an accurate prediction of survival must be available at the time of weaning from cardiopulmonary bypass. We, therefore, acquired 240 demographic, disease, and perioperative characteristics of 322 patients (mortality rate, 48.4%) who required IABP support to separate from bypass. Four variables available before or within 10 minutes of the first attempt at weaning from bypass significantly predicted mortality by stepwise logistic regression: complete heart block as demonstrated by need for temporary pacing at weaning (p < 0.001), advanced age (p < 0.002), preoperative blood urea nitrogen concentration (p = 0.036), and female sex (p = 0.048). An equation generated by the logistic model predicted a 72.2% survival rate in the 25% of patients at least risk (actual survival rate, 71.6%); in the 25% at greatest risk, death was predicted in 73.0%, and the actual mortality rate was 74.1%. The equation was then prospectively applied to 330 intraaortic balloon pump-supported patients managed at another institution. The overall mortality rate there was 41.2%; in the 25% at least risk, predicted survival rate was 70.5% (actual survival rate, 77.1%), and in the 25% at greatest risk, predicted mortality rate was 75.7% (actual mortality rate, 62.7%). Thus, retrospectively at one institution and prospectively at another, the equation generated by this model based only on data available at the time of weaning from bypass was able to define one subgroup of patients 2.6 to 2.7 times as likely to die as another subgroup from within similar cohorts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

A cost-effective Dacron annuloplasty ring.

Annuloplasty rings fashioned from Dacron tube grafts have been used in mitral valve operations at the Texas Heart Institute for the past 3 years. This technique has been applied in 70 consecutive patients, with excellent clinical and echocardiographic results. We have found that annuloplasty rings constructed from transverse sections of knitted Dacron offer the same advantages as other flexible rings at a greatly reduced cost.

Humans↗

PubMed1993

Peripheral organ perfusion augmentation during left ventricular failure. A controlled bovine comparison between the intraaortic balloon pump and the Hemopump.

Despite the use of inotropic therapy and the intraaortic balloon pump (IABP), inadequate peripheral organ perfusion and subsequent multiorgan failure from left ventricular dysfunction is a major cause of death following cardiac surgery. To compare the end-organ perfusion provided by the IABP with that of the recently developed Hemopump Cardiac Assist System, blood flow from visceral organs was measured by ultrasonic flow probes during separate periods of support with each of these pumps. Ten calves underwent coronary artery ligations with beta-receptor blockade; hemodynamic parameters were recorded before the induction of failure, during unsupported cardiac failure, and during Hemopump and IABP support. Improvement in mean cardiac output, mixed venous oxygen saturation, and pulmonary artery wedge pressure was significantly greater (p < 0.05) during Hemopump support than during IABP support. Renal artery flow was significantly greater during Hemopump support (276 +/- 74.2 cc/min) than during IABP support (164 +/- 79.6 cc/min). Hepatic artery flow was significantly greater during Hemopump support (34.7 +/- 25.7 cc/min) than during IABP support (24.4 +/- 18.9 cc/min), and portal vein flow was significantly greater during Hemopump support (1588 +/- 315 cc/min) than IABP support (1259 +/- 310 cc/min). There were no significant differences, however, between carotid artery flow during Hemopump support (292 +/- 171 cc/min) and that during IABP support (317 +/- 204 cc/min). We conclude that renal, hepatic, and mesenteric perfusion provided by the nonpulsatile Hemopump is superior to that of the IABP in this bovine model of left ventricular failure. Therefore, the Hemopump may be more effective in preventing multiorgan failure during recovery of ventricular function.

Animals↗

PubMed1993

Immunochemical identification of human endothelial cells on the lining of a ventricular assist device.

We are studying the biologic (pseudointimal) lining that forms in the HeartMate (Thermo Cardiosystems, Inc.; Woburn, Massachusetts, USA), a left ventricular assist device with a pusher-plate blood pump, housed in solid titanium with uniquely textured blood-contacting surfaces. Sintered titanium microspheres cover the rigid surface, and integrally textured polyurethane lines the flexing diaphragm. The texture of the blood-contacting surfaces is designed to encourage formation of a biologic pseudointimal lining, which greatly reduces the risk of thromboembolic complications. We performed immunochemical analyses to characterize precisely the pseudointimal lining. Samples were taken from 2 explanted pumps; 1 had supported a patient for 132 days and the other, 189 days. The samples were cultured to detect factor-VIII-related antigen (von Willebrand factor), acetyl low-density lipoprotein receptors, smooth-muscle-cell actin, and surface adhesion molecules specific for monocytes/macrophages. Macrophage cells were predominant in both pumps, but in the 2nd pump, cultures from the center of the diaphragm were positive for acetyl low-density lipoprotein receptor and von Willebrand factor, indicating the presence of endothelial cells. We believe that blood-borne endothelial cells or endothelial cell precursors were deposited on the blood-contacting surfaces, which is an important clinical finding with regard to lowering the risk of thromboembolic complications and reducing the need for systemic anticoagulation in long-term left ventricular assist device patients.

Actins↗

PubMed1992

Technique of open distal anastomosis for repair of descending thoracic aortic aneurysms.

Ischemic injury to the spinal cord and kidneys continues to be the major complication after resection of aneurysms involving the descending and proximal abdominal aorta. Our recent surgical experience with use of only a proximal clamp on the aorta to perform an "open" distal anastomosis has proved this technique to be safe and expeditious. We therefore compared our results using the technique of open distal anastomosis for aneurysm repair with those of the conventional two-clamp technique. Since January 1989, we have used the conventional two-clamp technique in 31 patients (group 1) and the technique of open distal anastomosis in 24 patients (group 2). No significant differences were noted between the two groups in terms of age, sex, cause of aneurysm, extent of aneurysm, or site of proximal cross-clamp. The average distal ischemic time was 31 minutes in group 1 patients and 26 minutes in group 2 patients. Renal insufficiency occurred in 8 of 31 patients in group 1 and in 0 of 24 patients in group 2 (p = 0.01). Neurologic complications occurred in 4 patients in group 1 and in 1 patient in group 2. Early mortality rates were similar for both groups (4 of 31 [13%], group 1; 4 of 24 [17%], group 2). Deaths were attributed to multiorgan failure and sepsis in 6 patients and coexisting coronary artery disease in 2 patients. Based on these results, we believe the technique of open distal anastomosis is safe and may improve the outcome in patients undergoing operation for descending thoracic aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗

PubMed1992

True aneurysm of the saphenous vein graft stump associated with CABG in a cardiac transplant patient.

Aneurysm of a saphenous vein graft after coronary artery bypass requires surgical resection because of its potential for rupture. This report describes a case of aneurysm formation in a 55-year-old man who underwent coronary artery bypass operation in 1977 and orthotopic heart transplantation 7 years later. A proximal vein graft remnant that had been ligated at the time of transplantation developed into a 5-cm aneurysm. In patients who have undergone previous coronary artery bypass operation, we recommend that the entire vein graft stump be excised and oversewn at the aortosaphenous anastomosis at the time of transplantation.

Aneurysm↗

PubMed1992

Mechanical support for intraventricular decompression in repair of left ventricular disruption.

Posterior disruption of the left ventricle is a difficult injury to repair and is associated with a high intraoperative mortality. We report a case of posterior disruption that occurred during a mitral valve operation. A conventional approach to repair failed after sutures tore through the myocardium. Intraventricular decompression to reduce ventricular wall tension and allow for successful suture repair of the injury was accomplished by insertion of a BioMedicus left ventricular assist device.

Aged↗

PubMed1992

Preoperative and postoperative Hemopump support for patients undergoing orthotopic heart transplantation.

The Hemopump (Johnson & Johnson Interventional Systems, Rancho Cordova, CA) can be used successfully as a bridge to cardiac transplantation in patients with advanced cardiogenic shock that proves to be irreversible. Some patients, however, may also benefit from maintaining Hemopump support for a period of time after transplantation. A technique has been developed for continuing Hemopump support after transplantation that does not require repositioning of the device.

Adult↗

PubMed1992

Recovery of pulmonary function in patients undergoing extended left ventricular assistance.

Heart transplantation should follow the implantation of a left ventricular assist device (LVAD) only after optimal postoperative recovery of pulmonary function. We reviewed hospital records of 12 patients who underwent extended (greater than 30 days) left ventricular support before transplantation to determine the rate of return of pulmonary function. The mean cardiac index and pulmonary capillary wedge pressure returned to normal in all patients within three days after LVAD implantation. The mean pulmonary artery pressure and pulmonary vascular resistance decreased but did not return to normal. The mean central venous pressure remained elevated throughout the first month but decreased by the time of transplantation. Supplemental oxygen requirements and peak airway pressures improved, and ten of the 12 patients were extubated by the fifth postoperative day. Preoperative roentgenographic evidence of pulmonary edema was present in eight patients, and pulmonary hilar prominence was present in the remaining four patients. Roentgenographic resolution of the pulmonary edema occurred slowly, persisting for one week after surgery in seven of eight patients. Ten patients were able to exercise strenuously 30 days after surgery, and 11 were returned to excellent condition before undergoing heart transplantation. Although the hemodynamic status in these patients significantly improved shortly after LVAD implantation, optimal recovery of pulmonary function required several weeks. Therefore, we advocate delaying transplantation after LVAD implantation to allow optimal pulmonary recovery.

Adult↗

PubMed1992

Management of patients supported on the Hemopump cardiac assist system.

The Hemopump Cardiac Assist System is a relatively new intraarterial, axial-flow circulatory assist device that offers temporary left ventricular support to patients in refractory cardiogenic shock, without requiring major surgery for insertion. Use of the Hemopump is associated with a low complication rate. Device-related morbidity is extremely rare. Because the Hemopump is safe for use in community hospitals, the number of patients supported by this device is expected to increase. In this report, we present general guidelines for the care of patients supported by the Hemopump. We describe techniques for the management of afterload reduction, supravalvular dislodgement, device malfunction, ventricular ectopy, intracardiac shunting, and inflow cannula obstruction.

Journal Article↗

PubMed1991

Subclavian vein-to-right atrial bypass for symptomatic venous hypertension.

A new surgical technique for bypassing subclavian vein thromboses in patients undergoing hemodialysis is presented. Subclavian vein stenosis or occlusion can occur after the use of temporary access catheters in subclavian vein dialysis. If this occurs in a patient with an arteriovenous access fistula of an ipsilateral upper extremity, venous hypertension, massive edema of the arm, and dysfunction of the access graft may result. In 2 patients with this condition, we successfully performed axillary vein-to-right atrial bypass, which resolved swelling and restored function of the access graft. This may be an appropriate surgical option for symptomatic venous hypertension in such patients.

Anastomosis, Surgical↗

PubMed1991

Myocardium-sparing cannulation technique for left ventricular assist device support.

The left atrium and the left ventricular apex are the most commonly used sites of inflow cannulation for postcardiotomy left ventricular support. A new cannulation technique that requires only an ascending aortotomy is introduced. This procedure can be undertaken with equipment present in any cardiac operating room and may prove to cause fewer complications than conventional cannulation techniques.

Aorta↗

PubMed1991

Patent foramen ovale: a cause of hypoxemia in patients on left ventricular support.

We describe 2 patients who experienced right-to-left shunting during support with a left ventricular assist device as a result of patent foramen ovale. In the first patient, the patent foramen ovale was not found until autopsy. In the second patient, fluctuations in continuous mixed venous oxygen saturations caused us to suspect a patent foramen ovale, which was confirmed with transesophageal contrast echocardiography. We promptly repaired the defect and this patient survived. When patients on assist devices experience unexplained arterial hypoxemia, a patent foramen ovale should be considered. If a patent foramen ovale is found, surgical correction should be done early.

Adult↗

PubMed1984

A comparison of in-vivo and imaginal participant modeling.

Recent research indicates that effective treatments of phobic reactions are often performance-based and involve exposure to the phobic object. The present study was designed to determine whether both of these components were necessary for the effectiveness of participant modeling procedures (N = 26). Phobic individuals were assigned randomly to one of two forms of participant modeling: In-vivo vs. imaginal. Both treatment analogues were identical except that the in-vivo version involved actual exposure to a phobic object, while the imaginal version simply required individuals to imagine that the phobic object was physically present. Results on behavioral and self-report measures indicated that both in-vivo and imaginal participant modeling were effective in generating increased approach behavior, but neither produced generalization beyond the laboratory setting. Explanations were discussed.

Adolescent↗

PubMedDate not supplied

Guillain-Barré syndrome after heart transplantation.

We present two cases of Guillain-Barré syndrome (acute idiopathic neuritis) that developed after heart transplantation involving immunosuppression with cyclosporine, azathioprine, and steroids. The literature contains only two previous reports of posttransplant Guillain-Barré syndrome, both involving patients maintained with azathioprine and steroid immunosuppression after kidney transplantation. In our two cases (and in one of the previous cases), the syndrome was preceded by a sudden increase in the amount of serum immunoglobulin M antibody to cytomegalovirus. One of our patients improved neurologically after plasmapheresis, but neither patient appeared to benefit from the administration of gamma globulin. Because further immunosuppression would predispose the transplant patient to other opportunistic infections, we advocate a trial of plasmapheresis in the treatment of Guillain-Barré syndrome in this population.

Cytomegalovirus Infections↗

PubMedDate not supplied

Long-term results in diabetic patients undergoing heart transplantation.

We conducted a retrospective study of 305 nondiabetic patients and 37 diabetic patients who underwent heart transplantation from July 1982 to May 1990. Actuarial survival was similar for both groups of patients at 1 year (76.4% versus 81.3%) and at 2 years (69.6% versus 73.0%). Because we were interested in long-term results, we further analyzed only those patients surviving more than 1 year after transplantation (214 nondiabetic patients and 29 diabetic patients). Mean follow-up for the nondiabetic patients was 31.8 +/- 16.2 months and for the diabetic patients, 32.9 +/- 4.1 months. The respective mean age in each group was 50.4 +/- 10.3 years and 51.6 +/- 9.1 years. No difference was observed between the nondiabetic patients and diabetic patients regarding the rejection rate per patient-month (0.040 +/- 0.041 versus 0.045 +/- 0.051 episodes per patient-month), the infection rate per patient-month (0.056 +/- 0.081 versus 0.081 +/- 0.102 episodes per patient-month), or renal function as evidenced by mean creatinine levels at 1, 2, and 3 years. Twelve patients were insulin-dependent before transplantation; and 1 year after transplantation, they required an insulin dose 2.12 times greater than the dose before operation. Coronary artery disease developed in 32.8% of the nondiabetic patients, compared with 31.0% of the diabetic patients by the fourth year of follow-up. Despite the need for increased insulin doses, the diabetic patients had similar long-term survival to that of the nondiabetic patients, without an increased risk of rejection, infection, renal dysfunction, or coronary artery disease. Our experience supports the feasibility of heart transplantation in selected diabetic recipients.

Adult↗

PubMedDate not supplied

Successful bridge to heart transplantation with a new left ventricular assist device.

During the last 5 years, a new pneumatically driven left ventricular assist device has been implanted in 18 heart transplantation candidates who required advanced mechanical circulatory support. The mean duration of support was 80 +/- 74 days, and the cumulative support time was 1400 days. Fifteen patients were successfully supported until the time of heart transplantation. As a result of early experience, in which three of four patients died after heart transplantation because their end-organ function failed to recover, subsequent efforts were made to institute support early, before irreversible organ damage occurred. Eleven of the 12 patients in the later experience are currently alive and well at a mean follow-up of 12.6 +/- 7.5 months. No thromboembolic episodes occurred, and minimal anticoagulation was required. Furthermore, patients were able to participate in rehabilitative exercise programs, thus optimizing their transplantation status. Finally, the findings in these patients have shown the feasibility of providing long-term, or even permanent, cardiac assistance.

Adult↗