ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Case Reports
Left ventricular assist device support of medically unresponsive pulmonary hypertension and aortic insufficiency.
Most centers consider medically unresponsive pulmonary hypertension an absolute contraindication to orthotopic cardiac transplantation because the alternative surgical therapy, heterotopic graft placement, is associated with decreased survival, although most patients normalize their pulmonary hemodynamics postoperatively. Orthotopic transplantation in patients with elevated, but responsive pulmonary pressures, also is associated with an increased operative mortality rate and decreased long-term survival. The authors present the case of a patient with medically unresponsive pulmonary hypertension who was mechanically supported in an effort to improve his orthotopic transplant candidacy and decrease his risk. ⋯ At 1 year after transplantation, pulmonary artery hemodynamics were normal (PA 34/14 mmHg, TPG at 8 mmHg, and PVR at 1.5 Wood units). The authors recommend the consideration of LVAD placement in patients with medically unresponsive pulmonary artery hypertension to assess PA responsiveness and improve the patient's orthotopic cardiac transplant candidacy and decrease the operative risk. However, several weeks may be needed for normalization of pressure and resistance.
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Encapsulation of hemoglobin within a liposome is one of the strategies in the development of artificial oxygen carriers. It maintains the oxygen transporting properties of hemoglobin and, at the same time, eliminates the side effects of cell free hemoglobin. Hemoglobin vesicles (HbV) are a type of liposome encapsulated hemoglobin. ⋯ Five percent albumin and washed rat red blood cells suspended in 5% albumin containing 10 g/dl of hemoglobin; were employed as controls. At the completion of a 90% exchange transfusion, renal cortical and skeletal muscle tissue oxygen tensions, along with oxygen delivery and consumption, were sustained almost equally well with the HbV suspension compared to the washed rat red blood cell suspension, but declined significantly with the albumin suspension. The results indicate that the oxygen transporting capability of HbV was almost equivalent to that of rat red blood cells.
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In their experimental approach to dynamic cardiomyoplasty (DCMP), the authors hypothesized that a wrapping method using the proximal part of a free latissimus dorsi muscle (LDM) graft might augment ventricular contractility more than the classic Carpentier's wrapping method. The authors divided 12 mongrel dogs into a pedicled LDM graft group (Group 1, n = 6) and a free LDM graft group (Group 2, n = 6) to evaluate the properties of the different wrapping methods. To evaluate the effect of DCMP on left ventricular systolic and diastolic function, the authors used precise indicators that minimize the influences of load conditions. ⋯ Free LDM grafts significantly increased left ventricular systolic function compared to the pedicled LDM. Although myocardial relaxation was impaired after LDM wrap in both groups, there was no difference between the two groups. The authors' results emphasize the explicit benefit of utilization of a free LDM graft in respect to left ventricular systolic function; the free LDM grafts have no gross detrimental effect on diastolic function when compared with a pedicle graft in the acute model.
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Between June 1986 and October 1995, 81 patients were emergently resuscitated with a portable extracorporeal life support (ECLS) system. Venoarterial perfusion was achieved using a centrifugal pump (BioMedicus; Medtronic, Anaheim, CA) and a hollow fiber oxygenator (BARD in 56 patients; Medtronic heparin-bonded MAXIMA, [MAXIMA, Medtronic, Minneapolis, MN] in the last 25 patients. The ECLS system was used at various locations in the hospital with the setup, priming, and initiation of perfusion done by ECLS trained intensive care unit nurses. ⋯ The ECLS system permitted an additional therapeutic surgical intervention in 45 cases. Patients who had a surgically remediable problem were more likely to survive. Prolongation of cardiopulmonary resuscitation beyond 30 mins before initiation of ECLS correlated with a decreased likelihood of survival.
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While the use of the centrifugal vortex ECMO pump as an alternative to a roller-occlusion pump offers distinct advantages, unacceptable hemolysis may occur during its use in newborn infants. The authors studied 87 consecutive neonatal patients with respiratory failure supported with venoarterial ECMO using a centrifugal vortex pump. Baseline mean plasma free hemoglobin level for all patients during the first 48 hours of bypass was 31.3 +/- 3.1 md/dl. ⋯ Mean plasma free hemoglobin decreased to baseline values following pump head change. The authors could not determine any factors that distinguish the infants who developed hemolysis from those who did not. Changing only the pump head provides a simple approach to hemolysis during use of the centrifugal vortex pump on newborn infants.