Abstract 5930: Pressure Increase After Peak Velocity in the Pulmonary Artery: A Novel Echocardiography Method to Identify Patients With Increased Pulmonary Vascular Resistance
Background. It is important to distinguish patients with pulmonary hypertension due to increased pulmonary vascular resistance (PVR) from those due to increased pulmonary capillary wedge pressure (PCWP), as it effects both treatment and prognosis. The normal pulmonary circulation is characterized by a compliant pulmonary artery (PA), low peripheral resistance, the absence of pressure reflection and a small pressure increase (PI) after peak flow. Hypothesis: In the present study we hypothesized that the level of PI after peak velocity identifies patients with increased PVR.
Methods. Echocardiography and right heart catheterization (Swan-Ganz catheters, thermodilution for cardiac output) were performed within 24 hours at 106 occasions in 96 patients. The investigations were divided into a testing sample (n=53) and a validation sample (n=53). We measured the time interval from QRS to the peak velocity in the PA using pulsed Doppler. This interval was superimposed on the tricuspid regurgitant velocity envelope to calculate the pressure corresponding to the peak velocity (PAPV) using the Bernoulli equation. The PI was calculated as PASP-PAVP.
Results. The proportion of patients with increased catheter PASP>40 mmHg, PVR>3 Woods units (WU) and PCWP>12 mmHg were 77%, 70% and 46% respectively. The range for PASP was 14 –150 mmHg, for PVR 0.4 –23 WU and for PCWP 1–34 mmHg. The mean±SD (range) for PI was 16±14 (0 –56) mmHg. The correlation between PVR and PI was moderate (R=0.66, p<0.0001). The receiver operator characteristic curve in the testing sample for PI to detect PVR>3 WU had an area under the curve (95% CI) of 0.95 (0.89 –1.0). The Table⇓ shows the sensitivity, specificity, positive (PV+) and negative predictive (PV−) values using different cut-offs in the validation sample.
Conclusion. In the present study we describe a novel and easily obtainable echocardiography parameter that identifies patients with pulmonary hypertension and increased PVR.