Pediatric Cardiology and Cardiac Surgery
Vol.26 No.5 2010 (416-422)
Ayumu Masuoka,1) Toshiyuki Katogi,1) Takaaki Suzuki,1) Mika Iwazaki,1) Toshiki Kobayashi,2)Hideaki Sennzaki,2) Hirotaka Ishido,2) Yoichi Iwamoto,2) Takashi Nishimura,3) and Shunei Kyo3)
Department of 1)Pediatric Cardiac Surgery, 2)Pediatric Cardiology, Saitama International Medical Center, Saitama Japan, 3)Department of Cardiovascular Surgery, Tokyo University, Tokyo Japan
Background: In Japan, adult-sized Toyobo-National Cardiovascular Center ventricular assist devices (VADs) are used, but VADs designed mainly for pediatric patients are not clinically available.
Methods: We present here 3 difficult cases of adult-sized Toyobo VADs used in pediatric patients weighing less than 25 kilograms. All 3 patients were suffering from cardiogenic shock, pulmonary edema, and multiple organ failure before the implantation of the VAD.
Results: In Case 1 (patient weighing 24 kg), after the implantation of a VAD, the post-operative course was complicated by bleeding, but the mode of driving the VAD was uneventful .The child was transferred to Germany for heart transplantation, but a serious cerebral infarction precluded him from receiving it. He returned to Japan and died 697 days after the implantation of the VAD. In Case 2 (patient weighing 16 kg), the VAD was driven at a pumping rate of 105 beats per minute, but the driving chamber was only half filled because of the low body weight. Ten days after the implantation of the VAD, a device-related cerebral infarction occurred. After the infarction, we completely changed the driving mode. The VAD pumping rate was decreased to 50 beats per minute, and the pumping chamber was fully filled for each stroke. This mode of driving caused extremely high blood pressure for this small child, and the vigorous use of antihypertensive drugs was mandatory. She was transferred to the United States and received a successful heart transplant. The driving mode of Case 3 was governed by the lessons learned from Case 2. The pumping rate was set to 46 beats per minute, but driving modes from 100% full to 100% empty caused hypertension. Vigorous use of antihypertensive drugs was mandatory in this case also. She was transferred to Germany and received a successful heart transplant.
Conclusions: Using adult-sized VADs for small children is difficult. Implantation in itself is not very difficult even with their small thoraxes. However, the post-implant management is very difficult due to the relatively large size of the pump; reducing the stroke volume of the VAD according to body weight is complicated by clot formation and cerebral infarctions. We changed our driving strategy from reducing the stroke volume to extremely reducing the pump rate to avoid clot formation. The large stroke volume causes hypertension for these small children, and large doses of antihypertensive drugs were needed to protect them from complications such as cerebral bleeding.