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Sixteen patients diagnosed with an aneurysm of abdominal aorta or Leriche disease underwent elective aortic surgery involving crossclamping of infrarenal aorta (ICC). These patients were randomized into two equal groups and 8 patients were infused with nifedipine starting from the isolation of aorta until the end of surgery (group A) while another 8 patients were infused with low-dose dopamine (group B) over the same surgical course. Plasma endothelin (ET) was measured before the induction of anesthesia, at the beginning and at the end of the clamp period and at the end of the operation. Intraoperatively, creatinine clearance and urinary excretion of PGE₂, 6-keto PGF_1α and TxB₂ were also determined before, during and after aortic crossclamping. Pre-operative GFR as well as preinduction cardiac index (CI) and pulmonary capillary wedge pressure (PCWP) of the two groups did not differ. During crossclamping plasma ET rose significantly in both groups. However, after clamp removal, plasma ET decreased in group A while it remained elevated in group B. Urinary excretion of TxB₂, PGE₂ and 6-keto PGF_1α increased during clamp in both groups, but the ratio of PGE2 + 6-keto PGF_1α/TxB₂ during and after clamp was significantly higher in group A than in B. Postclamp creatinine clearance decreased in group B, and increased in group A; postoperative value of GFR was unchanged in group A and decreased significantly in group B. In conclusion, infusion of nifedipine, in contrast to dopamine, prevented the decrease of GFR in patients undergoing aortic surgery. This effect could be mediated by a nifedipine modulation of ET vascular synthesis and/or a preferential renal synthesis of vasodilating prostanoids.

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Correspondence: Massimo Bertolissi, bertolissi@rodax.net ∆p SSP/RVSP = pressure gradient between systolic systemic pressure and right ventricular systolic pressure; ∆p DSP/mRVDP = pressure gradient between diastolic systemic pressure and the mean right ventricular diastolic pressure (the mean value between diastolic and end diastolic right ventricular pressures); PLE = passive leg elevation; RVEDVI = right ventricular end diastolic volume index; RVED V/P = right ventricular end diastolic volume/pressure ratio; RVEF = right ventricular ejection fraction; RVESVI = right ventricular end systolic volume index. AbstractIntroduction: 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. Methods: 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°, 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%. Results: 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/m 2 ), the right ventricular end systolic volume index (from 61 ± 13 to 77 ± 24 ml/m 2 ), 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/m 2 ), 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/m 2 ) 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. Conclusions: 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 gradie...