AbstractsMedical & Health Science

Deceleration time of systolic pulmonary venous flow - a new clinical marker of left atrial pressure. J.O. Hunderi, C.R. Thompson and O.A. Smiseth. Institute for Surgical Research and Dep. Cardiology, Rikshospitalet University Hospital, Oslo, Norway and St. Paul's Hospital, Univ. British Columbia, Vancouver, Canada. Background and aim: The curvilinearity of the atrial pressure-volume curve implies that atrial compliance decreases progressively with increasing left atrial pressure (LAP). We predict that reduced atrial compliance leads to more rapid deceleration of systolic pulmonary venous flow. With this rationale we investigate if the deceleration time (tdec) of pulmonary venous systolic flow reflects mean LAP. Methods: In 8 patients during coronary surgery, before extracorporeal circulation, pulmonary venous flow (PVF) by ultrasonic transit time, and invasive LAP were recorded during stepwise volume loading. The tdec was calculated as indicated on the Figure. Left atrial compliance was calculated as the systolic pulmonary vein flow integral divided by pressure. Results: Volume loading increased mean LAP from 11 ± 3 to 20 ± 5 mm Hg (p <0.001), reduced left atrial compliance from 2.2 ± 1.3 to 1.2 ± 0.8 ml/mm Hg (p <0.004), and reduced tdec from 320 ± 50 to 170 ± 40 ms (p <0.0005). Mean LAP correlated well with tdec (Figure). Conclusion: Elevated LAP caused a decrease in atrial compliance and thus more rapid deceleration of systolic pulmonary venous flow. The tdec has potential to become a clinical, semiquantitative measure of LAP.