Koichi Kashiwa

Midterm outcome of implantable left ventricular assist devices as a bridge to transplantation: Single-center experience in Japan

BACKGROUND Two implantable continuous-flow left ventricular assist devices (LVADs), DuraHeart (Terumo Heart, Ann Arbor, MI, USA) and EVAHEART (Sun Medical, Nagano, Japan), were approved in Japan in April 2011. We analyzed the midterm outcome of patients implanted with these implantable LVADs at the University of Tokyo Hospital. METHODS AND RESULTS A total of 31 patients who underwent implantation of LVADs (10 DuraHeart, 21 EVAHEART) as a bridge to transplantation at our institution between April 2011 and August 2013 were retrospectively reviewed. All patients were followed up through December 2013. Seven patients underwent conversions from NIPRO paracorporeal LVAD (Nipro, Osaka, Japan) to an implantable LVAD. The mean observation period was 483±239 days (41.0 patient years). Eight patients were transplanted and one patient showed functional recovery with subsequent LVAD explantation. Four patients died due to cerebrovascular accident, empyema, or device malfunction due to pump thrombosis after cerebral bleeding. Kaplan-Meier analysis revealed 6-, 12-, and 24-month survival rates of 93%, 86%, and 86%, respectively. The rates of freedom from cerebrovascular accidents and device-related infections at 1 year after LVAD implantation were 65% and 36%, respectively. Twenty-nine patients were discharged home after LVAD implantation. During the period of this study, there were 59 readmissions (53 urgent, 6 elective) among 22 patients (76%). The overall and urgent readmission rates were 1.66 and 1.49 per patient year, respectively. The common reason for readmission was device-related infection (31%), followed by cerebrovascular accidents (17%). The total out-of-hospital time after the primary discharge was 90%. CONCLUSIONS Our midterm survival rate after LVAD implantation is satisfactory. However, patients undergoing LVAD support were often readmitted with adverse events.

Central extracorporeal membrane oxygenation requiring pulmonary arterial venting after near-drowning

Extracorporeal membrane oxygenation (ECMO) is an effective respiratory and circulatory support in patients in refractory cardiogenic shock or cardiac arrest. Peripheral ECMO sometimes requires left heart drainage; however, few reports state that pulmonary arterial (PA) venting is required during ECMO support. We present a case of a 14-year-old boy who required PA venting during ECMO support after resuscitation from near-drowning in freshwater. A biventricular assist device with an oxygenator implantation was intended on day 1; however, we were unable to proceed because of increasing of pulmonary vascular resistance from the acute lung injury. Central ECMO with PA venting was then performed. On day 13, central ECMO was converted to biventricular assist device with an oxygenator, which was removed on day 16. This case suggests that PA venting during ECMO support may be necessary in some cases of respiratory and circulatory failure with high pulmonary vascular resistance after near-drowning.

Hemodynamic influence of tilting disc valve type on pump performance with the NIPRO-ventricular assist device

The NIPRO-ventricular assist device (NIPRO-VAD) is an external pulsatile flow pump. Formerly, Sorin Carbocast, a monoleaflet tilting disc valve (SC valve), was used at the inlet/outlet parts of the pump, but Medtronic Hall (MH valve) is now used. We studied the differences in performance among pumps with different artificial valves. Six NIPRO pumps with SC valves and six with MH valves were examined using mock circuits. The systolic flow of the pump was measured with the ultrasonic flowmeter by changing the systolic fraction. Six patients wearing the NIPRO-VAD underwent periodic pump exchange from a pump with an SC valve to the one with an MH valve. The pump blood flow was measured at pre- and post-pump exchanges using an ultrasonic flowmeter. Blood pressure, serum LDH and AST levels were also compared before and after the pump exchange. Blood flow was significantly increased by using the NIPRO-VAD with the MH valve as compared to the SC valve in vitro. Under the same drive conditions pump flow tended to increase in six patients. No difference was found in patients’ blood pressure, serum LDH or AST levels when using the SC or MH valve. From these results, the hemodynamic influence on patients due to replacement of the SC valve with the MH valve in the NIPRO-VAD is considered to be insignificant.

Electromagnetic interference between continuous-flow left ventricular assist device and cardiac resynchronization therapy defibrillator due to an unrecognized mechanism

a University of Tokyo Hospital, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan b Department of Cardiovascular Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan c Department of Pain and Palliative Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan d Department of Medical Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan e Department of Cardiovascular Surgery, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan f Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Research Division Gobancho Building, 7, Gobancho, Chiyodaku, Tokyo 102-0076, Japan g Translational Systems Biology and Medicine Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8655, Japan h Department of Cardiovascular Surgery, Kinki University School of Medicine, 377-2 Onohigashi, Osakasayama, Osaka 589-8511, Japan