A Novel Non-Invasive Method of Estimating Pulmonary Vascular Resistance in Patients With Pulmonary Arterial Hypertension
ABSTRACT The assessment of pulmonary vascular resistance (PVR) plays an important role in the diagnosis and management of pulmonary arterial hypertension (PAH). The main objective of this study was to determine whether the noninvasive index of systolic pulmonary arterial pressure (SPAP) to heart rate (HR) times the right ventricular outflow tract time-velocity integral (TVI(RVOT)) (SPAP/[HR x TVI(RVOT)]) provides clinically useful estimations of PVR in PAH.
Doppler echocardiography and right-heart catheterization were performed in 51 consecutive patients with established PAH. The ratio of SPAP/(HR x TVI(RVOT)) was then correlated with invasive indexed PVR (PVRI) using regression and Bland-Altman analysis. Using receiver operating characteristic curve analysis, a cutoff value for the Doppler equation was generated to identify patients with PVRI > or = 15 Wood units (WU)/m2.
The mean pulmonary arterial pressure was 52 +/- 15 mm Hg, the mean cardiac index was 2.2 +/- 0.6 L/min/m2, and the mean PVRI was 20.5 +/- 9.6 WU/m2. The ratio of SPAP/(HR x TVI(RVOT)) correlated very well with invasive PVRI measurements (r = 0.860; 95% confidence interval, 0.759-0.920). A cutoff value of 0.076 provided well-balanced sensitivity (86%) and specificity (82%) to determine PVRI > 15 WU/m2. A cutoff value of 0.057 increased sensitivity to 97% and decreased specificity to 65%.
The novel index of SPAP/(HR x TVI(RVOT)) provides useful estimations of PVRI in patients with PAH.
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ABSTRACT: Genetically modified mice offer the unique opportunity to gain insight into the pathophysiology of pulmonary arterial hypertension. In mice, right heart catheterization is the only available technique to measure right ventricular systolic pressure (RVSP). However, it is a terminal procedure and does not allow for serial measurements. Our objective was to validate a noninvasive technique to assess RVSP in mice. Right ventricle catheterization and echocardiography (30-MHz transducer) were simultaneously performed in mice with pulmonary hypertension induced acutely by infusion of a thromboxane analogue, U-46619, or chronically by lung-specific overexpression of interleukin-6. Pulmonary acceleration time (PAT) and ejection time (ET) were measured in the parasternal short-axis view by pulsed-wave Doppler of pulmonary artery flow. Infusion of U-46619 acutely increased RVSP, shortened PAT, and decreased PAT/ET. The pulmonary flow pattern changed from symmetrical at baseline to asymmetrical at higher RVSPs. In wild-type and interleukin-6-overexpressing mice, the PAT correlated linearly with RVSP (r(2)=-0.67, P<0.0001), as did PAT/ET (r(2)=-0.76, P<0.0001). Sensitivity and specificity for detecting high RVSP (>32 mm Hg) were 100% (7/7) and 86% (6/7), respectively, for both indices (cutoff values: PAT, <21 ms; PAT/ET, <39%). Intraobserver and interobserver variability of PAT and PAT/ET were <6%. Right ventricular systolic pressure can be estimated noninvasively in mice. Echocardiography is able to detect acute and chronic increases in RVSP with high sensitivity and specificity as well as to assess the effects of treatment on RVSP. This noninvasive technique may permit the characterization of the evolution of pulmonary arterial hypertension in genetically modified mice.Circulation Cardiovascular Imaging 03/2010; 3(2):157-63. DOI:10.1161/CIRCIMAGING.109.887109 · 6.75 Impact Factor
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ABSTRACT: Ultrasound imaging has continuously developed over recent years, leading to the development of several novel echocardiographic indexes. Among these, of particular interest are those that focus on pulmonary hemodynamics, because they not only improve both sensitivity and specificity in the echocardiographic evaluation of pulmonary pressures (systolic, mean, and diastolic), but can also be used to estimate other pulmonary hemodynamic parameters, such as pulmonary vascular resistance, pulmonary capillary wedge pressure, and pulmonary capacitance and impedance. Such parameters can provide important diagnostic and prognostic information in patients with heart failure, chronic obstructive pulmonary disease, and pulmonary arterial hypertension and in every patient with suspected pulmonary impairment. In this review, the authors present a comprehensive overview of the echocardiographic indexes involved in pulmonary hemodynamic evaluation and discuss the applications of these indexes in the clinical setting.Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 03/2010; 23(3):225-39; quiz 332-4. DOI:10.1016/j.echo.2010.01.003 · 3.99 Impact Factor
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ABSTRACT: Echocardiographic ratio of peak tricuspid regurgitant velocity to the right ventricular outflow tract time-velocity integral (TRV/TVI rvot) was presented as a reliable non-invasive method of estimating pulmonary vascular resistance (PVR). Studies using this technique in patients with moderate to high PVR are scarce. Left ventricular outflow tract time-velocity integral (TVI lvot) can be easier to measure than TVI rvot, especially in patients with severe pulmonary hypertension (PH) with significant anatomical modifications of the right structures. We wanted to determine whether the TRV/TVI rvot and TRV/TVI lvot ratios would form a reliable non-invasive tool to estimate PVR in a cohort of patients with moderate to severe pulmonary vascular disease. Doppler echocardiographic examination and right heart catheterisation were performed in 37 patients. Invasive PVR was compared with TRV/TVI rvot and TRV/TVI lvot ratios using regression analysis. Two equations were modelled and the results compared with invasive measurements using the Bland-Altman analysis. Using receiver-operating characteristics curve analysis, a cut-off value for the two ratios was generated. Correlation coefficients between invasive PVR and TRV/TVI rvot then TRV/TVI lvot were respectively 0.76 and 0.74. Two new equations were found but the Bland-Altman analysis showed wide standard deviations (respectively 3.8 and 3.9 Wood units). A TRV/TVI rvot then TRV/TVI lvot ratio cut-off value of 0.14 had a sensitivity of 93% and a specificity of 57% for the first and a sensitivity of 87% and a specificity of 57% for the second to determine PVR > 2 Wood units. Echocardiography is useful for the screening of patients with pulmonary hypertension and PVR > 2 WU. It remains disappointing for accurate assessment of high PVR. TVI lvot may be an alternative to TVI rvot for patients for whom accurate TVI rvot measurement is not possible.Cardiovascular Ultrasound 06/2010; 8:21. DOI:10.1186/1476-7120-8-21 · 1.28 Impact Factor