[Effects of intra-aortic balloon pumping on mitral flow dynamics after aortocoronary bypass surgery]

Improvement in left ventricular function following intra-aortic balloon pumping (IABP) in 15 patients (aged 51 to 86 years) after coronary artery bypass grafting was evaluated. Using transesophageal atrial echocardiography, the mitral flow velocity integrals in the rapid filling phase (IntR) and in the contraction phase (IntA) were measured from transmitral flow patterns, and the sum of IntR and IntA (IntR + IntA), and the ratios of IntA to IntR (IntA/IntR) were calculated for ON and OFF states of balloon pumping (IABP OFF test). The same parameters were determined during 1:2 assist balloon pumping (IABP 1:2 test); the cardiac cycle with balloon assist was defined as "ON", and that without balloon assist as "OFF". 1. IABP OFF test: IABP increased IntR from 6.4 +/- 1.6 cm to 7.6 +/- 1.9 cm (p less than 0.01), suggesting that a decreased afterload improves left ventricular relaxation. IntA did not change with balloon assist (ON 3.5 +/- 1.2 cm, OFF 3.7 +/- 1.2 cm). IntR + IntA increased from 10.0 +/- 2.0 cm to 11.1 +/- 2.4 cm during IABP (p less than 0.01). IABP reduced the IntA/IntR from 0.62 +/- 0.25 to 0.50 +/- 0.20 (p less than 0.01). The increment in the IntA/IntR without IABP suggests that impaired diastolic filling of the left ventricle due to an increased afterload may be compensated for by enhanced left atrial contraction.(ABSTRACT TRUNCATED AT 250 WORDS)