In vitro and in vivo characterization of three different modes of pump operation when using a left ventricular assist device as a right ventricular assist device.

Dual rotary left ventricular assist devices (LVADs) have been used clinically to support patients with biventricular failure. However, due to the lower vascular resistance in the pulmonary circulation compared with its systemic counterpart, excessively high pulmonary flow rates are expected if the right ventricular assist device (RVAD) is operated at its design LVAD speed. Three possible approaches are available to match the LVAD to the pulmonary circulation: operating the RVAD at a lower speed than the LVAD (mode 1), operating both pumps at their design speeds (mode 2) while relying on the cardiovascular system to adapt, and operating both pumps at their design speeds while restricting the diameter of the RVAD outflow graft (mode 3). In this study, each mode was characterized using in vitro and in vivo models of biventricular heart failure supported with two VentrAssist LVADs. The effect of each mode on arterial and atrial pressures and flow rates for low, medium, and high vascular resistances and three different contractility levels were evaluated. The amount of speed/diameter adjustment required to accommodate elevated pulmonary vascular resistance (PVR) during support with mode 3 was then investigated. Mode 1 required relatively low systemic vascular resistance to achieve arterial pressures less than 100 mm Hg in vitro, resulting in flow rates greater than 6 L/min. Mode 2 resulted in left atrial pressures above 25 mm Hg, unless left heart contractility was near-normal. In vitro, mode 3 resulted in expected arterial pressures and flow rates with an RVAD outflow diameter of 6.5 mm. In contrast, all modes were achievable in vivo, primarily due to higher RVAD outflow graft resistance (more than 500 dyn·s/cm(5)), caused by longer cannula. Flow rates could be maintained during instances of elevated PVR by increasing the RVAD speed or expanding the outflow graft diameter using an externally applied variable graft occlusion device. In conclusion, suitable hemodynamics could be produced by either restricting or not restricting the right outflow graft diameter; however, the latter required an operation of the RVAD at lower than design speed. Adjustments in outflow restriction and/or RVAD speed are recommended to accommodate varying PVR.

Use of recombinant activated Factor VII for refractory after lung transplant bleeding as an effective strategy to restrict blood transfusion and associated complications.

BACKGROUND: Recombinant activated factor VIIa (rFVIIa) has been increasingly used to stop massive bleeding after cardiothoracic surgical procedures. However, the risk : benefit profile of such a potent hemostatic agent remains unclear in the postsurgical patient, and the cost benefit is even less clear. In patients after lung transplantation, volume of blood transfused is of major concern, and all attempts are made to minimize large blood transfusions in this cohort. We report our experience with rFVIIa in patients with refractory bleeding after lung transplant surgery. STUDY DESIGN AND METHODS: All lung transplant patients who underwent single- or double-lung transplantation who received rFVIIa in the 5-year period, from January 2005 to June 2011, were included. A total of 15 patients were identified from a total of 95 lung transplant cases operated during this study period. Patient demographics, intra- and postoperative records were reviewed to assess the efficacy and safety of rFVIIa treatment. RESULTS: Patients with major bleeding treated with rFVIIa showed improved hemostasis with rapid normalization of coagulation variables. rFVIIa treatment was not associated with an increase in mechanical ventilation time, length of intensive care unit stay, or hospital stay compared to other lung transplant patients. In addition, the use of rFVIIa was associated with reduction in transfusion requirements of red blood cells, fresh-frozen plasma, and platelets (all p < 0.001). No definite thromboembolic-related event was recorded in our cohort. CONCLUSIONS: These data demonstrate that rFVIIa was associated with reduced blood loss, improvement of coagulation variables, and decreased need for transfusions. This reduction in losses led to a reduced requirement for blood transfusion, which may translate to a decrease in transfusion-related complications. Further investigation is needed to determine rFVIIa's safety and its efficacy in improving postoperative morbidity and mortality specifically in the field of post-lung transplantation surgery.

Determinants of in-hospital and long-term surgical outcomes after repair of postinfarction ventricular septal rupture.

OBJECTIVES: Surgical repair of post-myocardial infarction ventricular septal rupture is challenging with reported early mortality being substantial. In addition, congestive cardiac failure and ventricular tachyarrhythmia frequently occur long term after the operation, although frequency and predictive factors of these events have been poorly identified. METHODS: A consecutive series of 68 patients who underwent repair of postinfarction ventricular septal rupture by 14 surgeons between 1988 and 2007 was studied. Fifty-eight (85%) patients underwent repair in an urgent setting (<48 hours after diagnosis). Coronary artery bypass grafting was concomitantly performed in 48 (71%) patients. Mean follow-up period was 9.2 +/- 4.9 years. RESULTS: Thirty-day mortality was 35%, with previous myocardial infarction, previous cardiac surgery, preoperative left ventricular ejection fraction less than 40%, and urgent surgery being independent risk factors. Actuarial survival of 30-day survivors was 88% at 5 years, 73% at 10 years, and 51% at 15 years. Actuarial freedom from congestive cardiac failure and ventricular tachyarrhythmia was 70% and 85% at 5 years, 54% and 71% at 10 years, and 28% and 61% at 15 years, respectively. Independent predictors for congestive cardiac failure included hypertension, posterior septal rupture, residual interventricular communication, and preoperative left ventricular ejection fraction less than 40%, whereas concomitant ventricular aneurysmectomy and preoperative occlusion of the left anterior descending artery were independent predictors of ventricular tachyarrhythmia. CONCLUSIONS: Long-term outcomes after surgical repair of postinfarction ventricular septal rupture was favorable, despite infrequent exposure by individual surgeons to the pathologic features, indicating that an aggressive surgical approach is warranted. Predictors of congestive cardiac failure and ventricular arrhythmia long term varied.