Introduction: The aim of this study was to evaluate pulmonary vascular resistence /PVR/ by invasive and echocardiographic measurement in patients /pts/ with severe left ventricular /LV/ dysfunction. All the pts were candidates for CRT.
Methods: Standard transthoracic echocardiography and right heart (RH) catheterization were performed before CRT. Hemodynamic measurements, including mean pulmonary artery pressure (mPAP;mmHg), mean pulmonary capillary wedge pressure (PCWP;mmHg) and cardiac output (CO;L/min) were performed using a Swan-Ganz thermodilution catheter. PVR was estimated from hemodynamic measurements (PVR = (mPAP – PCWP )/CO; in Wood units (Wu)). Echocardiographic PVR was obtained using the peak tricuspid regurgitation velocity (TRV;m/s) and the time velocity integral (TVI;cm) of the right ventricular outflow tract (RVOT). Echo equation was: PVR = TRV/TVIRVOT x 10 + 0,16 (Wu). Before CRT and 3 month after, clinical evaluation ( NYHA functional class, 6-minute walking test (6MWT)) and echocardiographic parameters were evaluated. Clinical responders (R) to CRT were defined to NYHA definition (with reduction of functional class > or =1) and improvement of 6MWT.
Results: 22 pts (12 pts with CAD, 10 pts with DCMP, age 68.1±8.7 years; 19 men) with advanced heart failure (LVEF 21.8±4.5 %, NYHA III-IV, LVEDD 70.5±6.6 mm, LAESD 50.2±6.1 mm, mitral regurgitation 2.1±0.5 gr., tricuspid regurgitation 2.0±0.7 gr.) were included in analysis. RH catheterization findings were: mPAP 35.3±11.3 mm Hg, PCWP 25.4±8.6 mm Hg, CO 3.5±0.9 L/min, PVRcat 2.64±1.78 Wu. Echocardiographic values were: TRV 3.0±1.1 m/s, TVIRVOT 16.1±6.0 cm, PVRecho 2.16±1.36 Wu. There was no significant difference between both PVR measurements (2.64±1.78 vs. 2.16±1.36 Wu; p=0.21) with r value of 0.79. 4 pts (18%) were non-responders (NR). Before CRT the values of PVR were significantly higher in NR (NR 4.93±2,0 Wu vs. R 2,21±1,20 Wu; p<0.001). Also transpulmonary gradient (mPAP – PCWP) was significantly higher in NR (NR 15.3±5.1 mm Hg vs. R 8.0±3.1 mm Hg; p<0.05).After 3 month despite echo equation PVR decreased, still remained significantly higher in NR (NR 2.23±0.96 Wu vs R 1.37±0.92 Wu; p<0.05).
Conclusions: 1/ Our preliminary results indicate singnificant difference of PVR a transpulmonary gradient values in the response to CRT. But these results should be confirmed in larger group of pts. 2/ A positive correlation between echocardiographic and invasive PVR equation in pts with severe LV dysfunction was demonstrated.