Influence of passive leg elevation on the right ventricular function in anaesthetized coronary patients

The aim of the present study was to evaluate the haemodynamic effects of passive leg elevation on the right ventricular function in two groups of patients, one with a normal right ventricular ejection fraction (RVEF) and one with a reduced RVEF.

Twenty coronary patients undergoing elective coronary artery bypass grafting surgery were studied by a RVEF pulmonary artery catheter. The haemodynamic data reported were collected before the induction of anaesthesia (time point 1), just before (time point 2) and 1 min (time point 3) after the legs were simultaneously raised at 60 degrees, and 1 min after the legs were lowered (time point 4). The patients were divided into two groups: group A, with preinduction RVEF > 45%; and group B, with preinduction RVEF < 40%.

In group A (n = 10), at time point 3 compared with time point 2, the heart rate significantly decreased (from 75 +/- 10 to 66 +/- 7 beats/min). The right ventricular end diastolic volume index (from 105 +/- 17 to 133 +/- 29 ml/m2), the right ventricular end systolic volume index (from 61 +/- 13 to 77 +/- 24 ml/m2), the systolic systemic arterial/right ventricular pressure gradient (from 93 +/- 24 to 113 +/- 22 mmHg) and the diastolic systemic arterial/right ventricular pressure gradient (from 58 +/- 11 to 66 +/- 12 mmHg) significantly increased. Also in group A, the cardiac index did not significantly increase (from 3.28 +/- 0.6 to 3.62 +/- 0.6 l/min/m2), the RVEF was unchanged, and the right ventricular end diastolic volume/pressure ratio (RVED V/P) did not significantly decrease (from 48 +/- 26 to 37 +/- 13 ml/mmHg). In group B (n = 6) at the same time, the heart rate (from 72 +/- 15 to 66 +/- 12 beats/min), the right ventricular end diastolic volume index (from 171 +/- 50 to 142 +/- 32 ml/m2) and the RVED V/P (from 71 +/- 24 to 39 +/- 7 ml/mmHg) significantly decreased. The cardiac index and the diastolic systemic arterial/right ventricular pressure gradient were unchanged in group B, while the RVEF and the systolic systemic arterial/right ventricular pressure gradient did not significantly increase, and the right ventricular end-systolic volume index did not significantly decrease. All results are expressed as mean +/- standard deviation.

We conclude that passive leg elevation caused a worse condition in the right ventricle of group B because, with stable values of cardiac index, of systolic systemic arterial/right ventricular pressure gradient and of diastolic systemic arterial/right ventricular pressure gradient (which supply oxygen), the RVED V/P (to which oxygen consumption is inversely related) markedly decreased. This is as opposed to group A, where the cardiac index, the systolic systemic arterial/right ventricular pressure gradient and the diastolic systemic arterial/right ventricular pressure gradient increased, and the RVED V/P slightly decreased. Passive leg elevation must therefore be performed cautiously in coronary patients with a reduced RVEF.