Deflation Timing Influences Intra-Aortic Balloon Pump-Mediated Carotid Blood Flow Reversal: A Case Report.

The patient is a 63-year-old man with stage D heart failure and a left ventricular ejection fraction of <20% who presented to the Houston Methodist Hospital with cardiogenic shock. As a part of his care, he underwent placement of an intra-aortic balloon pump (IABP). The IABP settings were for the balloon to inflate with the aortic dicrotic notch and to deflate near the end of diastole. After assessment of his heart failure status, the decision was to proceed with cardiac transplant evaluation, and he underwent routine pretransplant screening that included carotid Doppler ultrasonography. On ultrasound, he was found to have mild calcified atherosclerotic plaque in the left internal carotid artery and left bulb and the left external carotid artery without hemodynamically significant stenosis (<50%). The right carotid arteries were not interrogated because of the presence of a Swan–Gantz catheter and overlying bandages. The Doppler signal in the left internal carotid artery was consistent with the presence of mechanical flow augmentation from the IABP as evidenced by the second forward pulsation seen on pulsed wave Doppler (Figure 1). However, in addition to the second forward signal from IABP augmentation, there was also a notable flow reversal seen during mid to late diastole corresponding with active deflation of the balloon pump (Figure 1). It is clear that this flow reversal was caused by the IABP as it was absent when the IABP was placed on standby. After identifying this finding, bedside Doppler was again performed in the common carotid artery with the IABP on standby, 2:1, 3:1, and with deflation optimized to the absolute end of diastole (Figure 2). After acquiring signals, the net forward time velocity integral (TVI) for each setting was determined (Table). Balloon deflation was optimized by moving deflation to the absolute end of diastole. After optimization of IABP deflation timing, the combined native and augmented forward TVI was equivalent to the forward TVI with the balloon on standby (Table). Transcranial Doppler was performed after deflation adjustment and demonstrated no evidence of intracranial flow reversal.