To Balloon or Not to Balloon? The Effects of an Intra-Aortic Balloon-Pump on Coronary Artery Flow during Extracorporeal Circulation Simulating Normal and Low Cardiac Output Syndromes

Figure 1. In vitro mock-circuit setup: schematic (a) and real (b). Measurements were made at the coronary level with a flowmeter (CBF) and in the central aorta with a pressure sensor (PAo). (1) Hemodynamic resistances were fixed with Hoffmann clamps. (2) Systolo-diastolic varying resistance synchronized to pump pulsatility, simulating the effect of left ventricular contraction (PLv). (3) Compliance reservoir. ECMO drained liquid from the venous tank and injected it into the femoral artery.

Figure 2. Compliance reservoir schematic in two different conditions to derive the equations. To obtain physiological pulse pressure (PP) at the aortic level, (V0) was adjusted. The added compliance (Cres) was 1.03 mL/mmHg at HR of 60/min and 0.31 mL/mmHg at HR of 100 bpm.

Figure 3. Average of pressure waveforms at the ascending aorta level for a heart rate of 60 bpm (top) and a heart rate of 100 bpm (bottom). Baseline conditions (CO of 5 L/min) with and without IABP enabled are presented in columns (A) and (B), respectively. Severe HF scenarios (CO of 2 L/min) with and without IABP enabled are presented in (C,D). The waveforms (thin lines) are recorded on 8–10 consecutive cardiac cycles and averaged (thick lines).

Figure 4. Average of flow waveforms at the coronary artery level for a heart rate of 60 bpm (top) and a heart rate of 100 bpm (bottom). Baseline conditions (CO of 5 L/min) with and without IABP enabled are represented in columns (A) and (B), respectively. Severe HF scenarios (CO of 2 L/min) with and without IABP are represented in (C,D). The waveforms (thin lines) are recorded on 8–10 consecutives cardiac cycles and averaged (thick lines). The varying resistance model of the coronary was not enabled in this case.

Figure 5. Coronary mean flow in different clinical scenarios: (A) (HR 60 bpm) and (B) (HR 100 bpm). The different clinical scenarios highlight the impact of IABP at different CO. The first situation corresponds to a baseline condition with a cardiac output of 5 L/min without ECMO support. Low CO syndrome by gradually decreasing CO to 2 L/min compensated to a total of 5 L/min with ECMO.

Figure 6. Pressure waveforms at the ascending aorta level at the baseline condition (CO 5 L/min) (A) and in the severe LV failure condition (CO 2 L/min) (B) are presented for a heart rate of 60 bpm (continuous lines). The effect of enabling the IABP on the pressure waveforms is superposed (dashed line) and is highlighted by the area under the curves (AUC) emphasizing the pressure decrease during systolic and the increase during diastolic compared to the pressure waveform without enabling the IABP.