Background: Axial blood pumps have very successfully entered the arena of prolonged clinical support. However, they offer only limited inherent load-responsive mechanisms for adjusting pumping performance to venous return and changes in the physiologic requirements of the patient. Therefore, excessive ventricular unloading can be observed in various situations of temporarily reduced venous return. In this study we report severe ventricular arrhythmias closely related to suction events in rotary blood pumps, a phenomenon that has not been described previously.
Methods: Data from a clinical trial intended to prove the feasibility of an automatic speed control system for pump recipients were analyzed with regard to electrocardiographic changes during ventricular collapse. The occurrence of excessive unloading was detected by an automatic suction detection system. Electrocardiograms (ECGs) were classified semi-manually, aided by a graphical use interface. For statistical data analysis, Wilcoxon's signed-rank test was utilized.
Results: After automatic suction detection a significant increase in monomorphic ventricular tachycardia was observed, from 0.015 to 0.099 event per second (p < 0.05). Furthermore, it was found that arrhythmic activity in terms of morphologic ventricular tachycardia increased after suction from 0.009 to 0.014 event per second.
Conclusions: Excessive ventricular unloading of the left ventricle during continuous left ventricular support can induce ventricular arrhythmias. We detected evidence supporting an increase in arrhythmic activity after suction. This turned out to be a transient effect, which vanished within 5 minutes after suction. ECG events related to suction have a sudden onset and are severe ventricular arrhythmias, which can consist of even just one extrasystolic beat, and they usually cease after clearance of suction.