849 EFFECTS OF INTRA-AORTIC BALLOON PUMP DELAYED DEFLATION TIMING ON CAROTID BLOOD FLOW AND CARDIAC MECHANICS

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Abstract Background Intra-Aortic Balloon Pump (IABP) efficacy is critically affected by the inflation/deflation timing. Balloon deflation may cause a sucking effect, and a steal phenomenon on carotid flow. Delaying IABP deflation reduces the degree of this flow reversal, but at the same time exposes patients to the risk of increased proto-systolic afterload with detrimental effects on the LV. Hypothesis To investigate the effects of a delayed IABP deflation timing on cerebral blood flow and LV hemodynamics. Methods We prospectively evaluated 20 consecutive patients who received transfemoral IABP for cardiogenic shock (CS). Central aortic pressures (augmented diastolic [ADP], end-diastolic [EDP], assisted systolic [ASP] and mean aortic [MAP] pressures) were recorded from the IABP console simultaneously with ultrasound data. First ultrasound and haemodynamic measurements were collected during conventional IABP deflation timing (balloon deflation completed before onset of LV systole by automated ECG gating). Then, IABP deflation was manually delayed to the beginning of the QRS (early LV systole). After adjustment, counterpulsation was performed for a minimum of 2 minutes to achieve steady hemodynamics, then the same ultrasound and haemodynamic measurements were recollected. Results Mean age was 67±13 years, LVEF was 25±11%. At the carotid ultrasound, the delayed deflation increased the net forward velocity time integral (VTI) in the common carotid artery (18±9 vs 15±8 cm; p=0.001), by reducing the end-diastolic backward VTI (1±1 vs 4±2 cm; p<0.001) while having no effect on the overall forward VTI (19±9 vs 19±9 cm; p=0.294). Specifically, the delayed deflation increased the diastolic forward VTI (12±5 vs 10±4 cm]; p<0.001) while decreasing the systolic forward VTI (7±4 vs 9±4 cm]; p<0.005). On central aortic hemodynamics, the delayed deflation decreased the ASP (91±21 vs 97±20 mmHg; p=0.001), increased the EDP (60±11 vs 48±9 mmHg; p<0.001), the ADP (123±19 vs 119±19 mmHg; p<0.001) and the MAP (89±14 vs 80±12 mmHg; p<0.001). On echocardiography, the delayed deflation increased the LVOT VTI (15±4 vs 13±4 cm; p<0.001), decreased LV ejection time (202±44 vs 211±43 ms; p=0.005) but did not affect the isovolumetric contraction time (119±56 vs 119±58 ms; p=0.989), eventually reducing the total duration of LV systole (321±54 vs 330±50 ms; p=0.009). Conclusions In our cohort, a delayed IABP deflation strategy, evaluated by a multi-parametric yet relatively simple approach, demonstrated to be safe and was associated with both an increase cerebral perfusion and an improvement in cardiac mechanics.