M Haushofer

Low stroke rate and few thrombo-embolic events after HeartMate II implantation under mild anticoagulation

OBJECTIVES Bleeding and thrombo-embolism are two of the most threatening adverse events associated with the use of continuous flow left ventricular assist devices (LVADs) in the treatment of severe heart failure. We analysed our LVAD patients treated with the HeartMate II (HM II) device by following a low anticoagulation regimen. METHODS Between 2008 and February 2011, we implanted 40 HM II LVADs in our institution. Intention to treat was bridge to transplant in 25, destination therapy in 9, bridge to candidacy in 5 cases and bridge to recovery in 1 case. Heparin was started only after 24 h postoperatively, and Phenprocumon (Phen) was started after removal of all chest drains. International normalized ratio (INR) target in the years 2008-2009 was 2.5, and 2.0-2.5 since 2010. Acetyl salicylic acid (ASA) was prescribed 50-100 mg/day only in patients <55 years or in case of severe atherosclerotic disease of the right coronary artery. All data were analysed consecutively concerning thrombo-embolic and bleeding events. RESULTS Fifty-two percent of the patients were in INTERMACS level 1 or 2 at the time of implantation. The mean age was 58 ± 11 years, and the mean days under LVAD was 241 days (maximum: 1052 days). The survival rate was 87.5% after 30 years and 75% in the long term. Early postoperatively, no strokes or thrombo-embolic events occurred. In the long term, two patients suffered from ischaemic strokes, but recovered well. In both of these index events, the INR was lasting below 1.4. One of these two patients developed pump thrombosis additionally. Only three patients (ASA + Phen) developed gastrointestinal bleeding (7.5%). Two patients were withdrawn from Phen + ASA because of multiple angiodysplasia. CONCLUSIONS Compared with the literature, even a mild anticoagulation protocol does not increase the risk of thrombotic events, but reduces bleeding events in the use of an HM II LVAD.

Feasibility and efficacy of bypassing the right ventricle and pulmonary circulation to treat right ventricular failure: an experimental study

BackgroundRight ventricular failure (RVF) and -support is associated with poor results. We aimed for a new approach of right - sided assistance bypassing the right ventricle and pulmonary circulation in order to better decompress the right ventricle and optimize left ventricular filling.MethodsFrom a microaxial pump (Abiomed), a low resistance oxygenator (Maquet and Novalung) and two cannulas (28 and 27 Fr) a system was set up and evaluated in an ovine model (n = 7). Connection with the heart was the right and left atrium. One hour the system was operated without RVF and turned of again. Then a RVF was induced and the course with the system running was evaluated. Complete hemodynamic monitoring was performed as well as echocardiography, flow measurement and blood gas analysis.ResultsThe overall performance of the system was reliable. Without RVF no relevant changes of hemodynamics occurred; blood gases were supra normal. In RVF a cardiogenic shock developed (MAP 35 ± 13 mmHg, CO 1,1 ± 0,7 l/min). Immediately after starting the system the circulation normalized (significant increase of MAP to 85 ± 13 mmHg, of CO to 4,5 ± 1,9). Echocardiography also revealed right ventricular recovery. After stopping the system, RVF returned.ConclusionsBypassing the right ventricle and pulmonary circulation with an oxygenating assist device, which may offer the advantages of enhanced right ventricular decompression and augmented left atrial filling, is feasible and effective in the treatment of acute RVF. Long time experiments are needed.

Oxygenated shunting from right to left: a feasibility study of minimized atrio-atrial extracorporeal membrane oxygenation for mid-term lung assistance in an acute ovine model

OBJECTIVES Right ventricular failure is often the final phase in acute and chronic respiratory failure. We combined right ventricular unloading with extracorporeal oxygenation in a new atrio-atrial extracorporeal membrane oxygenation (ECMO). METHODS Eleven sheep (65 kg) were cannulated by a 28-Fr inflow cannula to the right atrium and a 25-Fr outflow cannula through the lateral left atrial wall. Both were connected by a serial combination of a microaxial pump (Impella Elect(®), Abiomed Europe, Aachen, Germany) and a membrane oxygenator (Novalung(®)-iLA membrane oxygenator; Novalung GmbH, Hechingen, Germany). In four animals, three subsequent states were evaluated: normal circulation, apneic hypoxia and increased right atrial after load by pulmonary banding. We focused on haemodynamic stability and gas exchange. RESULTS All animals reached the end of the study protocol. In the apnoea phase, the decrease in PaO2 (21.4 ± 3.6 mmHg) immediately recovered (179.1 ± 134.8 mmHg) on-device in continuous apnoea. Right heart failure by excessive after load decreased mean arterial pressure (59 ± 29 mmHg) and increased central venous pressure and systolic right ventricular pressure; PaO2 and SvO2 decreased significantly. On assist, mean arterial pressure (103 ± 29 mmHg), central venous pressure and right ventricular pressure normalized. The SvO2 increased to 89 ± 3% and PaO2 stabilized (129 ± 21 mmHg). CONCLUSIONS We demonstrated the efficacy of a miniaturized atrio-atrial ECMO. Right ventricular unloading was achieved, and gas exchange was well taken over by the Novalung. This allows an effective short- to mid-term treatment of cardiopulmonary failure, successfully combining right ventricular and respiratory bridging. The parallel bypass of the right ventricle and lung circulation permits full unloading of both systems as well as gradual weaning. Further pathologies (e.g. ischaemic right heart failure and acute lung injury) will have to be evaluated.

Inflammatory response in transapical transaortic valve replacement.

OBJECTIVE Transapical aortic valve implantation (TA-AVI) has become a fast growing alternative to conventional aortic valve replacement (cAVR) particularly for patients burdened with serious comorbidities. We investigated whether the inflammatory response triggered by TA-AVI reflects the less invasive nature of this procedure. METHOD In this prospective observational study 25 patients undergoing aortic valve replacement (AVR; 15 cAVR and 10 TA-AVI) were included. Serial plasma cytokine concentrations (IL-6, IL-8, and IL-10) were measured by commercially available enzyme-linked immunosorbent assay kits at six different time points before, during, and after surgery. RESULTS Plasma levels of all three cytokines increased during and after both procedures and returned to baseline before the patients discharge. Peak values of IL-6 were 258 ± 113 pg/mL in AVR patients versus 111 ± 101 pg/mL in TA-AVI patients and were reached 12 hours after surgery. For IL-8, peak values were 51 ± 29 pg/mL 1 hour after surgery in AVR patients versus 15 ± 20 pg/mL on wound closure in TA-AVI patients. Plasma levels of IL-6 and IL-8 were significantly reduced in the TA-AVI group as compared with cAVR. IL-10 is markedly activated in both groups yet its induction is more prominent in AVR patients with peak values of 51 ± 28 pg/mL for AVR versus 24 ± 18 pg/mL for TA-AVI on wound closure. CONCLUSION TA-AVI compared with cAVR results in a significant reduction but not elimination of a systemic inflammatory response, which is attributable to cardiopulmonary bypass-dependent and bypass-independent factors.