Invasive Pulmonary Vascular Resistance Research Articles

A simpler noninvasive method of predicting markedly elevated pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension.

Several echocardiographic methods to estimate pulmonary vascular resistance (PVR) have been proposed. So far, most studies have focused on relatively low PVR in patients with a nonspecific type of pulmonary hypertension. We aimed to clarify the clinical usefulness of a new echocardiographic index for evaluating markedly elevated PVR in chronic thromboembolic pulmonary hypertension (CTEPH). We studied 127 CTEPH patients. We estimated the systolic and mean pulmonary artery pressure using echocardiography (sPAPEcho, mPAPEcho) and measured the left ventricular internal diameter at end diastole (LVIDd). sPAPEcho/LVIDd and mPAPEcho/LVIDd were then correlated with invasive PVR. Using receiver operating characteristic curve analysis, a cutoff value for the index was generated to identify patients with PVR > 1000 dyn·s·cm−5. We analyzed pre‐ and postoperative hemodynamics and echocardiographic data in 49 patients who underwent pulmonary endarterectomy (PEA). In this study, mPAPEcho/LVIDd moderately correlated with PVR (r = 0.51, p < 0.0001). There was a better correlation between PVR and sPAPEcho/LVIDd (r = 0.61, p < 0.0001). sPAPEcho/LVIDd ≥ 1.94 had an 77.1% sensitivity and 75.4% specificity to determine PVR > 1000 dyn·s·cm−5 (area under curve = 0.804, p < 0.0001, 95% confidence interval [CI], 0.66–0.90). DeLong's method showed there was a statistically significant difference between sPAPEcho/LVIDd with tricuspid regurgitation velocity2/velocity–time integral of the right ventricular outflow tract (difference between areas 0.14, 95% CI, 0.00–0.27). The sPAPEcho/LVIDd and mPAPEcho/LVIDd significantly decreased after PEA (both p < 0.0001). The sPAPEcho/LVIDd and mPAPEcho/LVIDd reduction rate (ΔsPAPEcho/LVIDd and ΔmPAPEcho/LVIDd) was significantly correlated with PVR reduction rate (ΔPVR), respectively (r = 0.58, p < 0.01; r = 0.69, p < 0.05). In conclusion, the index of sPAPEcho/LVIDd could be a simpler and reliable method in estimating CTEPH with markedly elevated PVR and also be a convenient method of estimating PVR both before and after PEA.

Inaccuracy of a non-invasive estimation of pulmonary vascular resistance assessed by cardiovascular magnetic resonance in heart failure patients

Pulmonary vascular resistance (PVR) is a marker of pulmonary vascular remodeling. A non-invasive model assessed by cardiovascular magnetic resonance (CMR) has been proposed to estimate PVR. However, its accuracy has not yet been evaluated in patients with heart failure. We prospectively included 108 patients admitted with acute heart failure (AHF), in whom a right heart catheterization (RHC) and CMR were performed at the same day. PVR was estimated by CMR applying the model: PVR = 19.38 − [4.62 × Ln pulmonary artery average velocity (in cm/s)] − [0.08 × right ventricle ejection fraction (in %)], and by RHC using standard formulae. The median age of the cohort was 67 years (interquartile range 58–73), and 34% were females. The median of PVR assessed by RHC and CMR were 2.2 WU (1.5–4) and 5 WU (3.4–7), respectively. We found a weak correlation between invasive PVR and PVR assessed by CMR (Spearman r = 0.21, p = 0.02). The area under the ROC curve for PVR assessed by CMR to detect PVR ≥ 3 WU was 0.57, 95% confidence interval (CI): 0.47–0.68. In patients with AHF, the non-invasive estimation of PVR using CMR shows poor accuracy, as well as a limited capacity to discriminate increased PVR values.

555 Right ventricular longitudinal strain of patients with pulmonary hypertension

Abstract Introduction Noninvasive echocardiography evaluation of the right ventricle (RV) has been shown to have prognostic value in patients with pulmonary hypertension (PH). Recently, speckle-tracking echocardiography has emerged as a new tool in the RV assessment. In this study, we aimed to study the value of global longitudinal strain in the RV evaluation of these patients. Methods We collected clinical, laboratory, echocardiographic and right heart catheterization (RHC) data from consecutive patients referred to an expert tertiary care referral centre from 12/2016 to 11/2018. Global RV systolic peak longitudinal strain (RVS) and RV free wall peak longitudinal strain (RVFWS) (mean of the basal, mid- and apical-segments) were measured by speckle-tracking technique with Echo-Pac software from GE Healthcare®. Results Of the 97 included patients, 76% were female. The mean age was 65 ± 15 years. Most patients were in NYHA class II. Median time between TTE and RHC was 70 days [IQR 34 - 184]. Group 2 PH was the most frequent aetiology of PH (35), followed by group 1 (26), group 4 (18), group 5 (3) and group 3 (2). The echocardiographic evaluation of this population showed borderline parameters of RV dysfunction (tricuspid annular plane systolic excursion (TAPSE) 18 ± 4 mm, fractional area change (FAC) 33 ± 10% and S’ tricuspid wave 10 ± 3 cm/sec). Mean RV global strain was -15 ± 5 and RV free wall strain was -17 ± 7. Both strain parameters significantly correlated with other echocardiographic parameters such as TAPSE, FAC, Tricuspid S wave, RV diastolic diameter, eccentricity index (EI), systolic pulmonary artery pressure (SPAP), pulmonary acceleration time and presence of RV outflow tract notching. Strain parameters were also associated with pulmonary artery pressures and pulmonary vascular resistance (PVR) measured by RHC. Strain parameters did not correlate with PECP (p &amp;gt; 0.05). In multivariate analysis, RV global longitudinal strain predicted invasive mean pulmonary artery pressure and PVR independently of TAPSE and FAC (β=1.38, p &amp;lt; 0.001). RV global strain &amp;gt; -17.1 predicted PVR &amp;gt; 3 wood (OR 3.46, CI 1.50 - 8.02, AUC 0.72) and PMAP &amp;gt; 20 mmHg (OR 4.92, CI 1.67 - 14.51, AUC 0.78). TAPSE &amp;lt; 18 mm predicted PVR &amp;gt; 3 wood (OR 7.41, CI 2.99 - 18.36, AUC 0.72). Conclusion RV global and free wall longitudinal strain significantly correlate with other echocardiographic parameters of RV structure and function and with invasive pulmonary artery pressures and PVR. Abstract 555 Figure.

Reliability of Doppler echocardiography in the assessment of high pulmonary vascular resistance in patients with severe pulmonary arterial hypertension

BackgroundThe objective is to assess whether the squaring of tricuspid regurgitation velocity (TRV) gives an improved estimate of pulmonary vascular resistance (PVR) or is equivalent to the ratio of TRV and time velocity integral of right ventricular outflow tract (TVIRVOT) (TRV/TVIRVOT) for assessing PVR in patients with high PVR values. MethodsThirty patients predicted to have PVR >6 WU by Doppler were included in the present study. TRV and TVIRVOT were measured by echo Doppler. TRV/TVIRVOT and TRV2/TVIRVOT were calculated. PVRCATH was estimated within 2 h of Doppler study. Regression equations for calculating PVR from TRV/TVIRVOT (PVRECHO1) and TRV2/TVIRVOT (PVRECHO2) were developed. Bland–Altman analysis for agreement between PVRCATH and PVRECHO1, PVRECHO2 was carried out. ResultsThe mean value of PVRCATH was found to be 15.08 ± 7.03 WU. The calculated values of PVRECHO1 and PVRECHO2 were found to be 15.08 ± 6.34 WU and 15.05 ± 6.08 WU, respectively. The linear regression analysis carried out for PVRCATH and TRV/TVIRVOT showed good correlation (R = 0.84). Bland–Altman analysis showed excellent agreement between the two Doppler methods and invasive PVR with negligible bias. ConclusionNoninvasive estimation of PVR by Doppler is reliable even in patients with high PVR (>6 WU) and, squaring TRV is not superior to TRV alone.

Improving the echocardiographic assessment of pulmonary pressure using the tricuspid regurgitant signal-The "chin" vs the "beard".

Transthoracic echocardiography (TTE) is a fundamental investigation for the noninvasive assessment of pulmonary hemodynamics and right heart function. The aim of this study was to assess the correlation and agreement of Doppler calculation of right ventricular systolic pressure (RVSP) and pulmonary vascular resistance (PVR) using "chin" and "beard" measurements of tricuspid regurgitant velocity (TRVmax ), with invasive pulmonary artery systolic pressure (PASP) and PVR. One hundred patients undergoing right heart catheterisation (RHC) and near simultaneous transthoracic echocardiography were studied. TRVmax was recorded for "chin" measurement (distinct peak TRVmax signal) and where available (63 patients), "beard" measurement (higher indistinct peak TRVmax signal). Measurable TRV signal was obtained in 96 patients. Mean RVSPchin 54.7±22.7mmHg and RVSPbeard 68.6=23±26.3mmHg (P<.001). There was strong correlation between both RVSPchin and RVSPbeard with invasive PASP (Pearson's r=.9, R2 =0.82, P<.001 - r=.88, R=.78, P<.001, respectively.). Bland-Altman analysis for RVSPchin and RVSPbeard showed a mean bias of -0.5mmHg (95% limits of agreement -21.4 to 20.5mmHg) and -10.7 (95% LOA -35.5 to 14.2mmHg), respectively. Receiver operator characteristics of TRVmax "chin" and "beard" for diagnosis of pulmonary hypertension was assessed with optimal cut-offs being 2.8m/s (sensitivity 93%, specificity 87%) and 3.2m/s (sensitivity 91%, specificity 82%), respectively. There was similar correlation between PVRchin and PVRbeard (r=.87, R2 =0.75, P<.001 and r=.86, R2 =0.74, P<.001, respectively). At higher PVR, there was overestimation of calculated PVR using PVRbeard . The accuracy of noninvasive measurement of right heart pressures is increased using the "chin" in estimation of both RVSP and PVR.

Noninvasive Echocardiographic Measures of Pulmonary Vascular Resistance in Children and Young Adults with Cardiomyopathy

Patients with cardiomyopathy (CM) are at increased risk for pulmonary hypertension (PH). Data are lacking on the use of noninvasive PH measures by echocardiography in patients with CM. The aim of this study was to evaluate the correlation between Doppler-derived echocardiographic indices and catheterization-based measurement of pulmonary vascular resistance (PVR) in children and young adults with CM. Imaging studies were retrospectively reviewed from pediatric patients with CM who underwent both echocardiography and cardiac catheterization within a 72-hour period. The ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral, the S/D ratio, and right ventricular myocardial performance index were correlated with invasive PVR. Receiver operating characteristic curves were developed to determine cutoffs for detecting PVR ≥ 6 indexed Wood units, a value associated with higher heart transplantation risk. Twenty-three patients with CM (median age, 11.7years; range, 0.5-21years) met the criteria for analysis,the majority (n=17 [74%]) of whom had dilated CM. Linear regression showed significant correlations between echocardiography-based ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral, S/D ratio, and right ventricular myocardial performance index versus invasive PVR (r=0.84, r=0.72, and r=0.72, respectively, P<.001). All echocardiographic measures showed high sensitivity, specificity, and predictive values to detect PVR ≥ 6 indexed Wood units, with ratio of peak tricuspid regurgitation velocity to right ventricular outflow tract velocity-time integral demonstrating the highest area under the curve (0.958; 95% CI, 0.866-1). Right-sided Doppler-derived echocardiographic indices correlate with PVR measured by cardiac catheterization in children and young adults with CM. These parameters may serve as useful adjuncts in serial assessment of right ventricular hemodynamics in this population.

A novel echocardiography formula for calculating predicted pulmonary vascular resistance in patients with mitral stenosis

Background: Pulmonary vascular resistance (PVR) plays an important role in the natural history, prognosis, and outcome after valve intervention in patients with mitral stenosis (MS). The existing formula to estimate PVR by means of echocardiography is not readily applicable in the MS patient subset because it does not specifically calculate the risk of PVR in MS. The aim of this study was to find a new echocardiography formula to estimate PVR in MS.Methods: This diagnostic study was conducted in 2 stages. In the first stage, 58 consecutive subjects with MS were studied to find some model formulas for estimating PVR by multiple regression. Eight echo parameters were analyzed to seek their correlation with the invasive PVR value as a gold standard. The formula that had the best correlation and was easiest to use would be selected. In the second stage, those model formulas were validated by applying them to a further 34 consecutive MS subjects.Results: Four formulas which gave a discriminator coefficient of r2 0.62–0.68 were derived. The best model formula was proposed for further application. The new selected formula PVR=-7.465+3.566 TRvmax –(0.23 TVs’)+6.799 (RV-MPI) showed good correlation (r=0.71, p&lt;0.001) to the invasive PVR value, with good reliability. TRvmax is maximal velocity of tricuspid regurgitation, TVs’ is systolic velocity of tricuspid annulus, and RV-MPI is right ventricle index myocardial performance. ROC curve showed that the cut off point 7.2 has good sensitivity and specificity (90% and 88%, respectively) to predict PVR 7 WU.Conclusion: This study has shown that a novel echocardiography formula can estimate PVR with good correlation and reliability in subjects with mitral stenosis.

Right Ventricular Outflow Tract Doppler Envelope Notching Predicts Pulmonary Vascular Resistance in Patients with Advanced Liver Disease

Portopulmonary hypertension (POPH) affects 6% of liver transplant (LT) candidates and is associated with poor outcomes. Screening for POPH with a transthoracic echocardiogram (TTE) is the standard of care, but diagnosis requires right heart catheterization (RHC) which carries risks in pts with advanced liver disease (ALD). Systolic deceleration or “notching” of the right ventricular outflow tract Doppler flow velocity envelope (FVERVOT) correlates with high pulmonary vascular resistance (PVR) in mixed pulmonary hypertension (PH) but has not been validated in pts with ALD. The ratio of peak tricuspid regurgitant velocity (TRV, m/s) and time-velocity integral of the RVOT (TVIRVOT) per the formula PVR=TRV/TVIRVOT x 10 has been shown to reliably estimate PVR. We investigated whether PVR can be predicted by the shape of FVERVOT or estimated by the TRV/TVIRVOT ratio in pts undergoing evaluation for LT. We included 100 pts who underwent RHC and TTE as part of LT evaluation from 01/10 to 03/15. Median time between the two tests was 5 days. We categorized the shape of FVERVOT as no (NN), late-systolic (LSN) or mid-systolic (MSN) notching. Unpaired t-tests were used to compare sample means for continuous variables and linear regression analysis to test the correlation between invasive and non-invasive PVR. The mean patient age was 57±8.5 years; 50% were male with diverse etiologies of ALD (35% HCV, 21% alcoholic, 10% cryptogenic, 6% NASH, 4% autoimmune, 24% other) and 79% were transplanted. The prevalence of POPH as defined by PVR≥3 on RHC was 12%. Elevated systolic pulmonary artery pressure (PAPs≥40mmHg) on TTE was present in 54% and mean PAP≥25mmHg on RHC in 24%. The shape of the FVERVOT Doppler exhibited NN in 81%, LSN in 10% and MSN in 9%. Pts with either LSN or MSN had higher mean PAP than those with NN (28±9 vs 35±11mmHg, p=0.007) and higher transpulmonary gradient (TPG), diastolic pulmonary gradient (DPG) and PVR; the difference between LSN and MSN was not significant. TAPSE was lower in pts with LSN or MSN compared to NN (Fig 1), and non invasively estimated PVR was higher (1.8±0.5 vs 1.4±0.5 WU, p=0.003). Poor correlation was observed between noninvasive and invasive PVR (R2=0.10, p=0.001). RVOT notching and non-invasive PVR were poor predictors of mortality. Elevated PAPs on TTE was a sensitive but not specific screening tool for PVR≥3 (Sn=82%, Sp=48%). RVOT Doppler flow velocity notching reliably predicts POPH in pts with ALD.

Noninvasive Monitoring of Serial Changes in Pulmonary Vascular Resistance and Acute Vasodilator Testing Using Cardiac Magnetic Resonance

The study sought to evaluate the ability of cardiac magnetic resonance (CMR) to monitor acute and long-term changes in pulmonary vascular resistance (PVR) noninvasively. PVR monitoring during the follow-up of patients with pulmonary hypertension (PH) and the response to vasodilator testing require invasive right heart catheterization. An experimental study in pigs was designed to evaluate the ability of CMR to monitor: 1) an acute increase in PVR generated by acute pulmonary embolization (n = 10); 2) serial changes in PVR in chronic PH (n = 22); and 3) changes in PVR during vasodilator testing in chronic PH (n = 10). CMR studies were performed with simultaneous hemodynamic assessment using a CMR-compatible Swan-Ganz catheter. Average flow velocity in the main pulmonary artery (PA) was quantified with phase contrast imaging. Pearson correlation and mixed model analysis were used to correlate changes in PVR with changes in CMR-quantified PA velocity. Additionally, PVR was estimated from CMR data (PA velocity and right ventricular ejection fraction) using a formula previously validated. Changes in PA velocity strongly and inversely correlated with acute increases in PVR induced by pulmonary embolization (r = -0.92), serial PVR fluctuations in chronic PH (r = -0.89), and acute reductions during vasodilator testing (r = -0.89, p ≤ 0.01 for all). CMR-estimated PVR showed adequate agreement with invasive PVR (mean bias -1.1 Wood units,; 95% confidence interval: -5.9 to 3.7) and changes in both indices correlated strongly (r = 0.86, p < 0.01). CMR allows for noninvasive monitoring of acute and chronic changes in PVR in PH. This capability may be valuable in the evaluation and follow-up of patients with PH.

Noninvasive Assessment of Pulmonary Vascular Resistance by Doppler Echocardiography

The ratio of tricuspid regurgitation velocity (TRV) to the time-velocity integral of the right ventricular outflow tract (TVIRVOT) has been studied as a reliable measure to distinguish elevated from normal pulmonary vascular resistance (PVR). The equation TRV/TVIRVOT × 10 + 0.16 (PVRecho) has been shown to provide a good noninvasive estimate of PVR. However, its role in patients with significantly elevated PVR (> 6 Wood units [WU]) has not been conclusively evaluated. The aim of this study was to establish the validity of the TRV/TVIRVOT ratio as a correlate of PVR. The role of TRV/TVIRVOT was also compared with that of a new ratio, TRV(2)/TVIRVOT, in patients with markedly elevated PVR (>6 WU). Data from five validation studies using TRV/TVIRVOT as an estimate of PVR were compared with invasive PVR measurements (PVRcath). Multiple linear regression analyses were generated between PVRcath and both TRV/TVIRVOT and TRV(2)/TVIRVOT. Both PVRecho and a new derived regression equation based on TRV(2)/TVIRVOT: 5.19 × TRV(2)/TVIRVOT - 0.4 (PVRecho2) were compared with PVRcath using Bland-Altman analysis. Logistic models were generated, and cutoff values for both TRV/TVIRVOT and TRV(2)/TVIRVOT were obtained to predict PVR > 6 WU. One hundred fifty patients remained in the final analysis. Linear regression analysis between PVRcath and TRV/TVIRVOT revealed a good correlation (r = 0.76, P < .0001, Z = 0.92). There was a better correlation between PVRcath and TRV(2)/TVIRVOT (r = 0.79, P < .0001, Z = -0.01) in the entire cohort as well as in patients with PVR > 6 WU. Moreover, PVRecho2 compared better with PVRcath than PVRecho using Bland-Altman analysis in the entire cohort and in patients with PVR > 6 WU. TRV(2)/TVIRVOT and TRV/TVIRVOT both predicted PVR > 6 WU with good sensitivity and specificity. TRV/TVIRVOT is a reliable method to identify patients with elevated PVR. In patients with TRV/TVIRVOT > 0.275, PVR is likely > 6 WU, and PVRecho2 derived from TRV(2)/TVIRVOT provides an improved noninvasive estimate of PVR compared with PVRecho.

Noninvasive Estimation of PA Pressure, Flow, and Resistance With CMR Imaging: Derivation and Prospective Validation Study From the ASPIRE Registry

The aim of this study was to develop a composite numerical model based on parameters from cardiac magnetic resonance (CMR) imaging for noninvasive estimation of the key hemodynamic measurements made at right heart catheterization (RHC). Diagnosis and assessment of disease severity in patients with pulmonary hypertension is reliant on hemodynamic measurements at RHC. A robust noninvasive approach that can estimate key RHC measurements is desirable. A derivation cohort of 64 successive, unselected, treatment naive patients with suspected pulmonary hypertension from the ASPIRE (Assessing the Spectrum of Pulmonary Hypertension Identified at a Referral Centre) Registry, underwent RHC and CMR within 12 h. Predicted mean pulmonary arterial pressure (mPAP) was derived using multivariate regression analysis of CMR measurements. The model was tested in an independent prospective validation cohort of 64 patients with suspected pulmonary hypertension. Surrogate measures of pulmonary capillary wedge pressure (PCWP) and cardiac output (CO) were estimated by left atrial volumetry and pulmonary arterial phase contrast imaging, respectively. Noninvasive pulmonary vascular resistance (PVR) was calculated from the CMR-derived measurements, defined as: (CMR-predicted mPAP - CMR-predicted PCWP)/CMR phase contrast CO. The following composite statistical model of mPAP was derived: CMR-predicted mPAP = -4.6 + (interventricular septal angle × 0.23) + (ventricular mass index × 16.3). In the validation cohort a strong correlation between mPAP and MR estimated mPAP was demonstrated (R(2) = 0.67). For detection of the presence of pulmonary hypertension the area under the receiver-operating characteristic (ROC) curve was 0.96 (0.92 to 1.00; p < 0.0001). CMR-estimated PVR reliably identified invasive PVR ≥3 Wood units (WU) with a high degree of accuracy, the area under the ROC curve was 0.94 (0.88 to 0.99; p < 0.0001). CMR imaging can accurately estimate mean pulmonary artery pressure in patients with suspected pulmonary hypertension and calculate PVR by estimating all major pulmonary hemodynamic metrics measured at RHC.

Use of echocardiographic pulmonary acceleration time and estimated vascular resistance for the evaluation of possible pulmonary hypertension

BackgroundDuring ultrasound examination, tricuspid regurgitation may be absent or gives a signal that is not reliable for the estimation of systolic pulmonary pressure. The aim of this study was to evaluate the usefulness of acceleration time (AT) from the right ventricular outflow tract (RVOT) as an estimation of the trans-tricuspid valve gradient (TTVG) and to investigate the correlation between estimated and invasive pulmonary vascular resistance (PVR).MethodsThe AT was correlated to the TTVG measured with routine standard echocardiography in 121 patients. In a subgroup of 29 patients, systolic pulmonary pressure (SPAP) and mean pulmonary arterial pressure (MPAP) were obtained from recent right heart catheterization (RHC).ResultsWe found no significant correlation between the estimation of right atrial pressure (RAP) by echocardiography and the RAP obtained by RHC. Estimated SPAP (TTGV + RAP mean from RHC) showed a good linear relation to invasively measured SPAP. TTVG and AT showed a non-linear relation, similar to SPAP and MPAP measured by catheterization and AT. For detection of SPAP above 38 mmHg a cut-off for AT of 100 ms resulted in a sensitivity of 89% and a specificity of 84%. For detection of MPAP above 25 mmHg a cut-off for AT of 100 ms resulted in similar sensitivity and specificity. Invasive PVR and the ratio of TTVG and the time velocity integral of the RVOT (TVI RVOT ) had a strong linear relation.ConclusionsOur study confirms that AT appears to be useful for the evaluation of pulmonary hypertension. In high risk patients, an AT of less than 100 ms indicates a high probability of pulmonary hypertension. Furthermore, PVR estimation by ultrasound seems preferably be done by using the ratio of TTVG and TVI RVOT.

Noninvasive and Simple Assessment of Cardiac Output and Pulmonary Vascular Resistance With Whole-Body Impedance Cardiography Is Useful for Monitoring Patients With Pulmonary Hypertension

Right heart catheterization (RHC) is the gold standard for the diagnosis of pulmonary hypertension (PH) and a useful tool for monitoring PH. However, there are some disadvantages in the regular use of RHC because it is invasive. Noninvasive methods for monitoring hemodynamics are needed to manage patients with PH. In this study, we aimed to evaluate the reliability of noninvasive hemodynamic assessment with whole-body impedance cardiography (Non-Invasive Cardiac System [NICaS]) for PH. We investigated 65 consecutive patients undergoing RHC. Two-thirds of them had pulmonary arterial hypertension and one-third had chronic thromboembolic PH; 25% of the patients were receiving medical therapy. Cardiac output (CO) was estimated by NICaS (NI-CO), thermodilution (TD-CO), and the Fick method (Fick-CO). There was a strong correlation between NI-CO and TD-CO (r=0.715, P<0.0001) and Fick-CO (r=0.653, P<0.0001). Noninvasive pulmonary vascular resistance (PVR) was estimated using a conventional invasive equation with NI-CO, mean pulmonary arterial pressure was calculated by echocardiographic measurement, and pulmonary capillary wedge pressure was estimated at 10mmHg in all cases. NICaS-derived PVR was very strongly correlated with invasive PVR (TD-PVR: r=0.704, P<0.0001; Fick-PVR: r=0.702, P<0.0001). Noninvasive measurement of CO and PVR using NICaS and echocardiography is a useful tool for the assessment of PH.

Postoperative non-invasive assessment of pulmonary vascular resistance using Doppler echocardiography

Non-invasive monitoring of pulmonary vascular resistance (PVR) in postoperative cardiac surgery patients might be useful, particularly for management of pulmonary hypertension. For this purpose, we sought to assess Doppler echocardiography in the intensive care setting. In 73 patients, hemodynamics was measured using both, invasive gold standard (pulmonary artery catheter), and non-invasively by Doppler echocardiography. Four Doppler parameters: (1) tricuspid regurgitant velocity/time-velocity-integral of right ventricular outflow tract (TRV/VTI(RVOT)), (2) tricuspid annular systolic velocity (S'), (3) tricuspid annular strain, and (4) tricuspid annular strain rate, were compared with invasive PVR, using linear regression analysis and receiver-operating-characteristics. Patients without (n = 25, group 1) and patients with elevated left ventricular filling pressure (wedge pressure ≥ 15 mmHg, group 2, n = 48) were compared. Correlations were (1) R = 0.874, P < 0.0001, (2) R = -0.765, P < 0.0001, (3) R = 0.279, P = 0.009, (4) R = 0.378, P = 0.001. TRV/VTI(RVOT) showed prediction of PVR >300 dyn*s*/cm(5) (area-under-curve 0.975, cut-off 0.245, sensitivity 100%, specificity 91%). Strain correlated with PVR in group 2 patients only. TRV/VTI(RVOT) and tricuspid annular systolic velocity (S'), are useful for non-invasive monitoring of PVR in postoperative cardiac surgery patients with or without elevated left ventricular filling pressure. Strain may be used in patients with elevated filling pressure.

Echocardiographic assessment of pulmonary vascular resistance in pulmonary arterial hypertension

BackgroundEchocardiographic 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.AimsWe 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.MethodsDoppler 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.ResultsCorrelation 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.ConclusionEchocardiography 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.

Noninvasive Estimation of Pulmonary Vascular Resistance in Pulmonary Hypertension

Determination of pulmonary vascular resistance (PVR) in patients with suspected or known pulmonary hypertension (PH) requires right heart catheterization. Our purpose was to use Doppler echocardiography to estimate PVR in patients with PH. Patient population consisted of 52 patients (53 +/- 12 years; 35 females) who underwent Doppler echocardiography and right heart catheterization within 24 hours of each other. The ratio of peak tricuspid regurgitation velocity (TRV) and right ventricular outflow time-velocity integral (VTI(RVOT)) was measured via transthoracic echocardiography and correlated to invasively determined PVR. A linear regression equation was generated to determine PVR by echocardiography based upon the TRV/VTI(RVOT) ratio. PVR by echocardiography was compared to invasive PVR using Bland-Altman analysis. Significant correlation was demonstrated between TRV/VTI(RVOT) and PVR by catheterization (r = 0.73; P < 0.001). However, Bland-Altman analysis showed that agreement between PVR determined by echocardiography and invasive PVR was poor (bias = 0; standard deviation = 4.3 Wood units). In a subset of patients with invasive PVR < 8 Wood units (26 patients), correlation between TRV/VTI(RVOT) and invasive PVR was strong (r = 0.94; P < 0.001). In these patients, agreement between PVR by echocardiography and invasive PVR was satisfactory (bias = 0; standard deviation = 0.5 Wood units). There was no correlation between TRV/VTI(RVOT) and invasive PVR in patients with PVR > 8 Wood units (n = 26; r = 0.17). While TRV/VTI(RVOT) correlates significantly with PVR, using it to estimate PVR in a PH patient population cannot be recommended.

A Novel Non-Invasive Method of Estimating Pulmonary Vascular Resistance in Patients With Pulmonary Arterial Hypertension

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.

Noninvasive Estimation of Pulmonary Vascular Resistance by Doppler Echocardiography in Patients With Pulmonary Arterial Hypertension

Pulmonary vascular resistance (PVR) is an important hemodynamic variable in the management of patients with pulmonary hypertension. To establish a method of estimating PVR in patients with pulmonary arterial hypertension (PAH), Doppler echocardiography was performed within 24 hours of right heart catheterization in 43 patients with PAH (idiopathic PAH, n = 20; chronic thromboembolic pulmonary hypertension, n = 9; congenital heart disease, n = 9; and others). Correlations between invasive PVR and Doppler variables of pulmonary artery flow and tricuspid regurgitation were examined. Mean invasive PVR was 1,294 +/- 680 dyne s cm(-5). Linear regression analysis revealed significant correlations with invasive PVR for the time-velocity integral (TVI; r = -0.63, p = 0.009) of right ventricular outflow and peak tricuspid regurgitant pressure gradient (TRPG; r = 0.77, p <0.001). The TRPG/TVI ratio, which approximated the ratio of pulmonary artery pressure to pulmonary blood flow, showed an improved correlation coefficient of 0.82 (PVR = 187 + TRPG/TVI x 118, p <0.001). After excluding 5 patients with an intracardiac shunt, 26 of the remaining 38 patients (68%) met the hemodynamic criteria in international guidelines for the selection of lung transplantation candidates and were defined as the poor-prognosis group. A TRPG/TVI >7.6 showed 85% sensitivity and 92% specificity for identifying patients in the poor-prognosis group. In conclusion, TRPG/TVI provides a reliable estimation of PVR over a wide range in patients with PAH with various underlying causes.

Reliability of Echocardiography for Hemodynamic Assessment of End-Stage Heart Failure

The management of patients with end-stage heart failure is difficult and may require the monitoring of intracardiac pressures. The aim of this prospective study was to assess the reliability of echocardiography in patients with end-stage HF. Twenty consecutive patients presenting with severe left ventricular dysfunction in end-stage heart failure were prospectively studied. All patients underwent right-sided cardiac catheterization and transthoracic echocardiography. Right atrial pressure, estimated using a new echocardiographic parameter, was significantly improved. There was good agreement between systemic and pulmonary vascular resistance, determined by catheterization and echocardiography. All patients with echocardiographic pulmonary vascular resistance<6 Wood units also had invasive pulmonary vascular resistance<6 Wood units. Only echocardiographic mean right atrial pressure was related to the use of saline infusion or bolus infusion of furosemide. All patients requiring intravenous furosemide had pulmonary capillary wedge pressures persistently>or=15 mm Hg despite adequate medication. In conclusion, this study indicates that echocardiography may be a reliable tool for the management of patients with end-stage heart failure.

A simple method for noninvasive estimation of pulmonary vascular resistance

ObjectivesWe sought to test whether the ratio of peak tricuspid regurgitant velocity (TRV, ms) to the right ventricular outflow tract time-velocity integral (TVIRVOT, cm) obtained by Doppler echocardiography (TRV/TVIRVOT) provides a clinically reliable method to determine pulmonary vascular resistance (PVR). BackgroundPulmonary vascular resistance is an important hemodynamic variable used in the management of patients with cardiovascular and pulmonary disease. Right-heart catheterization, with its associated disadvantages, is required to determine PVR. However, a reliable noninvasive method is unavailable. MethodsSimultaneous Doppler echocardiographic examination and right-heart catheterization were performed in 44 patients. The ratio of TRV/TVIRVOTwas then correlated with invasive PVR measurements using regression analysis. An equation was modeled to calculate PVR in Wood units (WU) using echocardiography, and the results were compared with invasive PVR measurements using the Bland-Altman analysis. Using receiver-operating characteristics curve analysis, a cutoff value for the Doppler equation was generated to determine PVR >2WU. ResultsAs calculated by Doppler echocardiography, TRV/TVIRVOTcorrelated well (r = 0.929, 95% confidence interval 0.87 to 0.96) with invasive PVR measurements. The Bland-Altman analysis between PVR obtained invasively and that by echocardiography, using the equation: PVR= TRV/TVIRVOT× 10 + 0.16 , showed satisfactory limits of agreement (mean 0 ± 0.41). A TRV/TVIRVOTcutoff value of 0.175 had a sensitivity of 77% and a specificity of 81% to determine PVR >2WU. ConclusionsDoppler echocardiography may provide a reliable, noninvasive method to determine PVR.