This survey targeted 109 patients with approved implantable ventricular assist devices (iVADs) in Japan implanted from April 2011 to December 2016. We looked into the factors retrospectively from the point of view of type of the device, timing of the occurrence, and human factors. We defined handling mistakes in this survey as pump stoppage and driveline damage due to carelessness or wrong handling. The data were analyzed by Fisher’s exact test, and p<0.05 was considered statistically significant.
The total number of mistakes were 34 cases. The patients with EVAHEART ® didn’t make mistakes. The incidence rate of mistakes in DuraHeart ® and HeartMate II ® was 0.16, 0.11 cases/patient-year, respectively. The incidence rate in Jarvik 2000 ® was the highest among devices, which was 0.63 cases/patient-year. In these mistakes, the numbers of mistakes that patients made were 28, 82.4%. And, 21 cases in these mistakes that patients made was occurred less than 1st year from operation. Then, we studied the relationship between the handling mistakes and human factors. We divided the patients to those for whom device test was conducted more than one and result of trail making test-B (TMT-B) was more than cutoff value at one or more times, and the other. We studied the relationship between the results of these tests and the handling mistakes. It is considered significant (p=0.04). Therefore, the patients that test was conducted more than one and that result of TMT-B was more than cutoff value at one or more times have tendency to make handling mistakes. However, the sensitivity of this cutoff was 13.6%. Therefore, it was hard to detect the patients who make handling mistakes and there seems to be no way to take any measures for the specific patient population. Considering this study results, we strongly feel the importance of adapting fool proof and/or fault tolerant when designing the devices for reducing the frequency of mistakes in the handling of iVAD. We consider that if the driveline is connected to the controller with emergency battery, most of the cases of pump stoppage would not occur.