The relationship between plasma urotensin II (hU-II) and pulmonary artery occlusion pressure during cardiac surgery: further evidence that hU-II is influenced by cardiac filling pressures

Introduction

The (patho-)physiological role of human urotensin II (hU-II) - the most potent endogenous vasoconstrictor yet described - remains to be defined [1]. Preliminary evidence suggests that hU-II levels during cardiac surgery are increased in patients with myocardial dysfunction [2]. However, it is not known, if hU-II plasma concentrations are related to pulmonary capillary wedge pressure (PCWP) as an estimate of left ventricular filling pressure.

Methods

We investigated 33 consecutive patients during coronary artery bypass (CABG) surgery. Blood was sampled before induction of anesthesia (t1), 20 min after intubation (t2), 10 and 30 min after aortic cross clamping (t3 and t4) during cardiopulmonary bypass (CPB), and 30 min after CPB (t5). Hemodynamic variables (including PCWP) were recorded at t2 and t5. hU-II was determined by a commercially available ELISA.

Results

hU-II concentrations decreased during CPB and returned to baseline thereafter (Fig. 1). Plasma hU-II concentrations were significantly correlated with mean pulmonary artery pressure (MPAP) and PCWP before and after CPB (Spearman's rho: range: 0.52-0.62). Patients with a preoperative ejection fraction (EF) = 0.45 had higher hU-II levels before (P = 0.02) and immediately after CPB (P = 0.008) than patients with an EF = 0.5 (Fig. 1).

Figure 1

The course of plasma urotensin II (U-II) during cardiac surgery. For abbreviations and time points see text.

Conclusions

The correlation between hU-II concentrations, MPAP and PCWP during CABG surgery and its relation to the preoperative degree of myocardial dysfunction strongly suggest a role of left ventricular filling pressures in the regulation of plasma hU-II in patients with ischemic heart disease.