Echocardiographic assessment of pulmonary vascular resistance in pulmonary arterial hypertension

Septic cardiomyopathy phenotype in the critically ill may depend on antimicrobial resistance

Background

Sepsis is a life-threatening organ dysfunction, and septic cardiomyopathy (SCM) may complicate the course of the disease. Infection with multidrug-resistant (MDR) pathogens has been linked with worse outcomes. This study aims to evaluate SCM in patients with infections caused by different antimicrobial-resistant phenotypes.

Method

This retrospective study included patients with sepsis/septic shock, hospitalized, and intubated in the intensive care unit of the University Hospital of Larissa between January 2022 and September 2023 with echocardiographic data during the first two days after infection onset. The patients were divided into two groups: non-MDR-SCM group and MDR-SCM group. The cardiac function was compared between the two groups.

Result

A total of 62 patients were included in the study. Forty-four patients comprised the MDR-SCM and 18 the non-MDR-SCM group. Twenty-six patients (41.9%) presented with left ventricular (LV) systolic dysfunction, and ≤35% right ventricular fractional area change (RVFAC) was present in 56.4%. LV systolic function was more severely impaired in the non-MDR-SCM group (left ventricular ejection fraction, 35.8% ±4.9% vs. 45.6%±2.4%, P=0.049; LV outflow tract velocity time integral, [10.1±1.4] cm vs. [15.3±0.74] cm, P=0.001; LV-Strain, -9.02%±0.9% vs. -14.02%±0.7%, P=0.001). The MDR-SCM group presented with more severe right ventricular (RV) dilatation (right ventricular end-diastolic area/left ventricular end-diastolic area, 0.81±0.03 vs. 0.7±0.05, P=0.042) and worse RV systolic function (RVFAC, 32.3%±1.9% vs. 39.6%±2.7%, P=0.035; tricuspid annular plane systolic excursion, [15.9±0.9] mm vs. [18.1±0.9] mm, P=0.165; systolic tissue Doppler velocity measured at the lateral tricuspid annulus, [9.9±0.5] cm/s vs. [13.1±0.8] cm/s, P=0.002; RV-strain, -11.1%±0.7% vs. -15.1%±0.9%, P=0.002).

Conclusion

SCM related to MDR infection presents with RV systolic dysfunction predominance, while non-MDR-SCM is mainly depicted with LV systolic dysfunction impairment.

Comprehensive temporal analysis of right ventricular function and pulmonary haemodynamics in mechanically ventilated COVID-19 ARDS patients

BACKGROUND

Cardiac injury is frequently reported in COVID-19 patients, the right ventricle (RV) is mostly affected. We systematically evaluated the cardiac function and longitudinal changes in severe COVID-19 acute respiratory distress syndrome (ARDS) admitted to the intensive care unit (ICU) and assessed the impact on survival.

METHODS

We prospectively performed comprehensive echocardiographic analysis on mechanically ventilated COVID-19 ARDS patients, using 2D/3D echocardiography. We defined left ventricular (LV) systolic dysfunction as ejection fraction (EF) < 40%, or longitudinal strain (LS) > - 18% and right ventricular (RV) dysfunction if two indices among fractional area change (FAC) < 35%, tricuspid annulus systolic plane excursion (TAPSE) < 1.6 cm, RV EF < 44%, RV-LS > - 20% were present. RV afterload was assessed from pulmonary artery systolic pressure (PASP), PASP/Velocity Time Integral in the right ventricular outflow tract (VTIRVOT) and pulmonary acceleration time (PAcT). TAPSE/PASP assessed the right ventriculoarterial coupling (VACR).

RESULTS

Among 176 patients included, RV dysfunction was common (69%) (RV-EF 41.1 ± 1.3%; RV-FAC 36.6 ± 0.9%, TAPSE 20.4 ± 0.4mm, RV-LS:- 14.4 ± 0.4%), usually accompanied by RV dilatation (RVEDA/LVEDA 0.82 ± 0.02). RV afterload was increased in most of the patients (PASP 33 ± 1.1 mmHg, PAcT 65.3 ± 1.5 ms, PASP/VTIRVOT, 2.29 ± 0.1 mmHg/cm). VACR was 0.8 ± 0.06 mm/mmHg. LV-EF < 40% was present in 21/176 (11.9%); mean LV-EF 57.8 ± 1.1%. LV-LS (- 13.3 ± 0.3%) revealed a silent LV impairment in 87.5%. A mild pericardial effusion was present in 70(38%) patients, more frequently in non-survivors (p < 0.05). Survivors presented significant improvements in respiratory physiology during the 10th ICU-day (PaO2/FiO2, 231.2 ± 11.9 vs 120.2 ± 6.7 mmHg; PaCO2, 43.1 ± 1.2 vs 53.9 ± 1.5 mmHg; respiratory system compliance-CRS, 42.6 ± 2.2 vs 27.8 ± 0.9 ml/cmH2O, all p < 0.0001). Moreover, survivors presented significant decreases in RV afterload (PASP: 36.1 ± 2.4 to 20.1 ± 3 mmHg, p < 0.0001, PASP/VTIRVOT: 2.5 ± 1.4 to 1.1 ± 0.7, p < 0.0001 PAcT: 61 ± 2.5 to 84.7 ± 2.4 ms, p < 0.0001), associated with RV systolic function improvement (RVEF: 36.5 ± 2.9% to 46.6 ± 2.1%, p = 0.001 and RV-LS: - 13.6 ± 0.7% to - 16.7 ± 0.8%, p = 0.001). In addition, RV dilation subsided in survivors (RVEDA/LVEDA: 0.8 ± 0.05 to 0.6 ± 0.03, p = 0.001). Day-10 CRS correlated with RV afterload (PASP/VTIRVOT, r: 0.535, p < 0.0001) and systolic function (RV-LS, 0.345, p = 0.001). LV-LS during the 10th ICU-day, while ΔRV-LS and ΔPASP/RVOTVTI were associated with survival.

CONCLUSIONS

COVID-19 improvements in RV function, RV afterload and RV-PA coupling at day 10 were associated with respiratory function and survival.

Bedside Ultrasound for Hemodynamic Monitoring in Cardiac Intensive Care Unit

Thanks to the advances in medical therapy and assist devices, the management of patients hospitalized in cardiac intensive care unit (CICU) is becoming increasingly challenging. In fact, Patients in the cardiac intensive care unit are frequently characterized by dynamic and variable diseases, which may evolve into several clinical phenotypes based on underlying etiology and its complexity. Therefore, the use of noninvasive tools in order to provide a personalized approach to these patients, according to their phenotype, may help to optimize the therapeutic strategies towards the underlying etiology. Echocardiography is the most reliable and feasible bedside method to assess cardiac function repeatedly, assisting clinicians not only in characterizing hemodynamic disorders, but also in helping to guide interventions and monitor response to therapies. Beyond basic echocardiographic parameters, its application has been expanded with the introduction of new tools such as lung ultrasound (LUS), the Venous Excess UltraSound (VexUS) grading system, and the assessment of pulmonary hypertension, which is fundamental to guide oxygen therapy. The aim of this review is to provide an overview on the current knowledge about the pathophysiology and echocardiographic evaluation of perfusion and congestion in patients in CICU, and to provide practical indications for the use of echocardiography across clinical phenotypes and new applications in CICU.

A prediction model of simple echocardiographic variables to screen for potentially correctable shunts in adult patients with pulmonary arterial hypertension associated with atrial septal defects: a cross-sectional study

During the routine follow-up of adult patients with pulmonary arterial hypertension associated with atrial septal defects (ASD-PAH), the suitability of shunt closure depends on the invasive right heart catheterization (RHC). It is difficult to grasp the timing of RHC shunt closure for moderate-severe PAH. This retrospective cross-sectional study was designed to investigate which echocardiographic variables are related to pulmonary vascular resistance (PVR) in adult ASD-PAH patients and propose a method using echocardiographic variables to screen for patients where shunt closure is suitable. A total of 139 adult ASD-PAH patients with a PASP ≥ 60 mmHg measured by transthoracic echocardiogram (TTE) were included in this study. All RHCs were performed within a week after TTE. The Correctable shunt was defined as PVR ≤ 4.6 wood units (WU). Multivariate regressions were performed with echocardiographic variables. The nomogram of prediction model was constructed by the predictors of PVR ≤ 4.6 WU by multivariate logistic regression analysis. Multivariate linear regression revealed that TAPSE (tricuspid annular plane systolic excursion)/pulmonary artery systolic pressure (PASP) measured by TTE was negatively associated with PVR (β per SD: - 1.84, 95%CI - 2.62, - 1.06). Multivariate logistic regression showed that TAPSE/PASP and pulmonary valve (PV) peak velocity were positively associated with a potentially correctable shunt (PVR ≤ 4.6 WU) (OR per SD: 2.38, 95%CI 1.34, 4.25, and OR per SD: 2.67, 95%CI 1.26, 5.64, respectively). In receiver operating characteristic analysis, the TAPSE/PASP + PV peak velocity combined model achieved the best performance (AUC: 0.8584, sensitivity: 83.33%, specificity: 72.16%). Internal verification showed stable performance (AUC: 0.8591, sensitivity: 88.10%, specificity: 68.04%). The net benefit of this model was greater than other models when it came to a wide range probability threshold in decision curve analysis. TAPSE/PASP + PV the peak velocity model may have great value in predicting adult ASD-PAH patients with operability potential, which could help clinicians make the treatment decision for follow-up patients.

Right ventricular load and contractility in HIV-associated pulmonary hypertension

Background

People living with human immunodeficiency virus (PLWH) are at risk of developing pulmonary hypertension (PH) and right ventricular (RV) dysfunction, but understanding of the relationship of RV function to afterload (RV-PA coupling) is limited. We evaluated the clinical and hemodynamic characteristics of human immunodeficiency virus (HIV)-associated PH.

Methods

We performed a retrospective review of patients with a diagnosis of HIV undergoing right heart catheterization (RHC) from 2000–2016 in a tertiary care center. Inclusion criteria were diagnosis of HIV, age ≥ 18 years and availability of RHC data. PH was classified as either pulmonary arterial hypertension (PAH; mean pulmonary arterial pressure [mPAP] ≥ 25mmHg with pulmonary artery wedge pressure [PAWP] ≤ 15mmHg) or pulmonary venous hypertension (PVH; mPAP ≥ 25mmHg with PAWP > 15). We collected demographics, CD4 cell count, HIV viral load, RHC and echocardiographic data. The single beat method was used to calculate RV-PA coupling from RHC.

Results

Sixty-two PLWH with a clinical likelihood for PH underwent RHC. Thirty-two (52%) met PH criteria (15 with PAH, 17 with PVH). Average time from diagnosis of HIV to diagnosis of PH was 11 years. Eleven of 15 individuals with PAH were on antiretroviral therapy (ART) while all 17 patients with PVH were on ART. Compared to PLWH without PH, those with PH had an increased likelihood of having a detectable HIV viral load and lower CD4 cell counts. PLWH with PAH or PVH had increased RV afterload with normal RV contractility, and preserved RV-PA coupling.

Conclusion

PLWH with PH (PAH or PVH) were more likely to have a detectable HIV viral load and lower CD4 count at the time of RHC. PLWH with PAH or PVH had increased RV afterload, normal RV contractility, with preserved RV-PA coupling suggestive of an early onset, mild, and compensated form of PH. These results should be confirmed in larger studies.

Fetal umbilical, cerebral and pulmonary blood flow patterns in relation to lung function and asthma in childhood. The Generation R Study

BACKGROUND

Fetal growth restriction is associated with higher risks of childhood respiratory morbidity. Fetal blood flow adaptations might contribute to these associations. We examined the associations of fetal umbilical, cerebral, and pulmonary blood flow with wheezing patterns, lung function, and asthma in childhood.

METHODS

In a population-based prospective cohort study among 903 children, we measured fetal umbilical, cerebral, and pulmonary blood flow by pulsed-wave Doppler at a median gestational age of 30.3 (95% range 28.8-32.3) weeks. We obtained information about wheezing patterns until the age of 6 years by questionnaires. Lung function was measured by spirometry and information about current asthma was obtained by questionnaire at the age of 10 years.

RESULTS

Results showed a non-significant relationship between a higher umbilical artery pulsatility index (PI) and umbilical artery PI/cerebral artery PI ratio, indicating fetal blood flow redistribution at the expense of the trunk, with higher risks of early wheezing (OR [95% CI]: 2.07 (0.70-6.10) and 2.74 (0.60, 12.62) per unit increase, respectively). A higher pulmonary artery time velocity integral, indicating higher pulmonary vascular resistance, was associated with a higher risk of late/persistent wheezing (Z-score 1.14 [1.01-1.29]). A higher middle cerebral artery PI was associated with a higher FEV1 /FVC (Z-score [95% CI]: 0.21 [0.01-0.42]). Results did not materially change after additional adjustment for birth and growth characteristics.

CONCLUSION

Third-trimester fetal blood flow patterns might be related to childhood respiratory health. These findings should be considered as hypothesis generating and need further replication.

Analysis of Biphasic Right Ventricular Outflow Doppler Waveform in Patients with Pulmonary Hypertension

Pulmonary hypertension (PH) with pulmonary vascular disease (PVD) is a progressive and debilitating disease associated with increased pulmonary vascular resistance (PVR). Biphasic right ventricular outflow tract (RVOT) Doppler flow is frequently seen in severe PH patients with PVD. In association with hemodynamics, the precise analysis of biphasic RVOT Doppler flow (RVDF) has not been fully elucidated. Therefore, the purpose of the present study is to analyze the relation between the hemodynamics and indices of biphasic RVDF in PH patients with PVD.Seventy PH patients with biphasic RVDF were analyzed. All patients underwent transthoracic echocardiography and right heart catheterization. For the analysis of biphasic RVDF, the early waveform was determined as P₁ while the late waveform was determined as P₂. For each P₁ and P₂, the duration (D, seconds) and peak flow velocity (PFV, in m/second) were measured.P₁D and P₂PFV were significantly correlated with PVR (P₁D: r = -0.542, P < 0.0001, P₂PFV: r = -0.513, P < 0.0001). Therefore, we propose a novel RVDF formula for estimation of PVR, as follows. PVR = 26 - 77 × P₁D - 14 × P₂PFV. The PVR could be estimated by this proposed formula (r = 0.649, P < 0.0001), which is derived from one Doppler image only unlike previously used PVR prediction formula.P₁D and P₂PFV were associated with PVR. Moreover, this simple RVDF formula proposed herein can estimate PVR in PH patients with PVD.

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

BACKGROUND

The 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 (TVI_RVOT) (TRV/TVI_RVOT) for assessing PVR in patients with high PVR values.

METHODS

Thirty patients predicted to have PVR >6 WU by Doppler were included in the present study. TRV and TVI_RVOT were measured by echo Doppler. TRV/TVI_RVOT and TRV²/TVI_RVOT were calculated. PVR_CATH was estimated within 2 h of Doppler study. Regression equations for calculating PVR from TRV/TVI_RVOT (PVR_ECHO1) and TRV²/TVI_RVOT (PVR_ECHO2) were developed. Bland-Altman analysis for agreement between PVR_CATH and PVR_ECHO1, PVR_ECHO2 was carried out.

RESULTS

The mean value of PVR_CATH was found to be 15.08 ± 7.03 WU. The calculated values of PVR_ECHO1 and PVR_ECHO2 were found to be 15.08 ± 6.34 WU and 15.05 ± 6.08 WU, respectively. The linear regression analysis carried out for PVR_CATH and TRV/TVI_RVOT showed good correlation (R = 0.84). Bland-Altman analysis showed excellent agreement between the two Doppler methods and invasive PVR with negligible bias.

CONCLUSION

Noninvasive estimation of PVR by Doppler is reliable even in patients with high PVR (>6 WU) and, squaring TRV is not superior to TRV alone.

A novel predictor of clinical outcomes in patients with heart failure with preserved left-ventricular ejection fraction: a pilot study

Predictors of outcomes in patients with heart failure with preserved left-ventricular ejection fraction (HFpEF) remain unclear. The ratio of early diastolic transmitral flow velocity to early diastolic myocardial velocity (E/e') has been proposed, but the predictive accuracy remains unsatisfactory. We hypothesized that E/e' normalized by the stroke volume (SV), E/e'/SV, could be a good predictor of outcome in HFpEF patients by reflecting the terminal slope of the end-diastolic pressure-volume relation, i.e., stiffness of the left ventricle. This pilot study was conducted to propose a novel echocardiographic index for predicting the outcomes of patients with HFpEF. Echocardiography including E/e'/SV measurement was performed in consecutive 80 HFpEF patients at discharge in index hospitalization due to HF. The end points included the readmission for heart failure and cardiovascular death at 1 year after discharge. 19 patients (24%) met the end points. Receiver-operating characteristic analysis showed that E/e''/SV was a strong predictive factor (AUC = 0.78) compared to E/e' (AUC = 0.74). Kaplan-Meier analysis showed that patients with E/e'/SV > 0.40 had a poorer prognosis than those with E/e'/SV < 0.40 (p < 0.01). By Cox regression multi-variate analysis, a high E/e'/SV was an independent predictor of event-free survival [adjusted hazard ratio (95% CI) 14.26 (3.18, 63.93) (p = 0.01)]. E/e'/SV has potential to predict clinical outcomes in patients with HFpEF.

A novel scoring index by Doppler echocardiography for predicting severe pulmonary hypertension due to chronic lung diseases: a cross-sectional diagnostic accuracy study

Background

Severe pulmonary hypertension (PH) resulting from a chronic lung disease (CLD) (severe CLD-PH) requires more aggressive treatment due to its increased mortality compared with mild PH. Therefore, we developed a Doppler echocardiography scoring index (ESI) to predict severe CLD-PH.

Methods

A derivation cohort of 107 patients with CLD who underwent echocardiography was classified into two groups, the normal/mild PH group and the severe PH group, based on the right heart catheterization. Meanwhile, we designed the ESI by multivariate logistic regression to validate the predicted outcomes. The ESI was calculated using the following formula: ESI = ESI_RVEDTD + ESI_PASP + ESI_PAd − ESI_TAPSE. Additionally, the ESI was weighted by +2 points for right ventricular end-diastolic transverse dimension ≥3.8 cm or pulmonary artery diameter ≥2.7 cm, +3 points for systolic pulmonary artery pressure (PASP) ≥61 mmHg, and −3 points for tricuspid annular plane systolic excursion ≥1.65 cm.

Results

In the derivation cohort, PASP ≥61 mmHg estimated by echocardiography exhibited 80.4% sensitivity and 84.3% specificity with area under receiver-operating characteristic curve of 0.823 (95% CI: 0.797–0.942, P<0.0001). Compared with PASP, ESI ≥1.0 exhibited 91.1% sensitivity and 80.4% specificity, resulting in a net improvement in model performance with a change in the c-statistic from 0.823 to 0.937 and an integrated discrimination improvement of 11.3% (95% CI: 4.5%–18.2%, P=0.001). The ESI was applied to the validation cohort, resulting in 84.2% sensitivity and 81.3% specificity with 82.9% accuracy.

Conclusion

The ESI showed high capacity for predicting severe CLD-PH, further implying the value of noninvasive examinations in clinic.

4D magnetic resonance flow imaging for estimating pulmonary vascular resistance in pulmonary hypertension

PURPOSE

To develop an estimate of pulmonary vascular resistance (PVR) using blood flow measurements from 3D velocity-encoded phase contract magnetic resonance imaging (here termed 4D MRI).

MATERIALS AND METHODS

In all, 17 patients with pulmonary hypertension (PH) and five controls underwent right heart catheterization (RHC), 4D and 2D Cine MRI (1.5T) within 24 hours. MRI was used to compute maximum spatial peak systolic vorticity in the main pulmonary artery (MPA) and right pulmonary artery (RPA), cardiac output, and relative area change in the MPA. These parameters were combined in a four-parameter multivariate linear regression model to arrive at an estimate of PVR. Agreement between model predicted and measured PVR was also evaluated using Bland-Altman plots. Finally, model accuracy was tested by randomly withholding a patient from regression analysis and using them to validate the multivariate equation.

RESULTS

A decrease in vorticity in the MPA and RPA were correlated with an increase in PVR (MPA: R(2) = 0.54, P < 0.05; RPA: R(2) = 0.75, P < 0.05). Expanding on this finding, we identified a multivariate regression equation that accurately estimates PVR (R(2) = 0.94, P < 0.05) across severe PH and normotensive populations. Bland-Altman plots showed 95% of the differences between predicted and measured PVR to lie within 1.49 Wood units. Model accuracy testing revealed a prediction error of ∼20%.

CONCLUSION

A multivariate model that includes MPA relative area change and flow characteristics, measured using 4D and 2D Cine MRI, offers a promising technique for noninvasively estimating PVR in PH patients. J. MAGN. RESON. IMAGING 2016;44:914-922.

Noninvasive assessment of pulmonary vascular resistance by echocardiography in chronic thromboembolic pulmonary hypertension

BACKGROUND

Pulmonary vascular resistance (PVR) is an important parameter in the management of patients with chronic thromboembolic pulmonary hypertension (CTEPH), and numerous noninvasive methods for PVR prediction have been proposed. However, a systematic evaluation of the methods that are specific for CTEPH has not been conducted. We compared a variety of echocardiography-derived prediction indices with direct right heart catheterization (RHC) to identify the most reliable noninvasive indicator of PVR in patients with CTEPH.

PATIENTS AND METHODS

Echocardiography and RHC were performed sequentially in 40 patients (mean age: 62.4±11.4 years; 30 females) with CTEPH. We measured the peak flow velocity of tricuspid regurgitation (TRV), tricuspid regurgitation pressure gradient (TRPG), right ventricular outflow tract (RVOT) time-velocity integral (TVIRVOT), left ventricular outflow tract (LVOT) time-velocity integral (TVILVOT), cardiac output at RVOT (CORVOT), and the LVOT (COLVOT) using echocardiography. The parameters TRV/TVIRVOT, TRV/TVILVOT, TRV/CORVOT, TRV/COLVOT, TRPG/TVIRVOT, TRPG/TVILVOT, TRPG/CORVOT, and TRPG/COLVOT were then calculated to predict the PVR. Finally, correlations between these echocardiographic predictors of PVR and the PVR data obtained from RHC (PVRRHC) were assessed.

RESULTS

The mean pulmonary arterial pressure and PVRRHC were 32.1±11.4mmHg and 5.4±2.9 Wood units, respectively. TRV/TVIRVOT, TRV/TVILVOT, TRV/COLVOT, TRPG/TVIRVOT, TRPG/TVILVOT, TRPG/CORVOT, and TRPG/COLVOT were all significantly correlated with the PVRRHC, and TRPG/COLVOT was the most strongly correlated with the PVRRHC (r=0.807, p<0.001).

CONCLUSIONS

Echocardiographic measurement of TRPG/COLVOT is a reliable noninvasive predictor of PVR in CTEPH patients.

Hypoxia, not pulmonary vascular pressure, induces blood flow through intrapulmonary arteriovenous anastomoses

KEY POINTS

Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) is increased by acute hypoxia during rest by unknown mechanisms. Oral administration of acetazolamide blunts the pulmonary vascular pressure response to acute hypoxia, thus permitting the observation of IPAVA blood flow with minimal pulmonary pressure change. Hypoxic pulmonary vasoconstriction was attenuated in humans following acetazolamide administration and partially restored with bicarbonate infusion, indicating that the effects of acetazolamide on hypoxic pulmonary vasoconstriction may involve an interaction between arterial pH and PCO2. We observed that IPAVA blood flow during hypoxia was similar before and after acetazolamide administration, even after acid-base status correction, indicating that pulmonary pressure, pH and PCO2 are unlikely regulators of IPAVA blood flow.

ABSTRACT

Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) is increased with exposure to acute hypoxia and has been associated with pulmonary artery systolic pressure (PASP). We aimed to determine the direct relationship between blood flow through IPAVA and PASP in 10 participants with no detectable intracardiac shunt by comparing: (1) isocapnic hypoxia (control); (2) isocapnic hypoxia with oral administration of acetazolamide (AZ; 250 mg, three times a day for 48 h) to prevent increases in PASP; and (3) isocapnic hypoxia with AZ and 8.4% NaHCO3 infusion (AZ + HCO3 (-) ) to control for AZ-induced acidosis. Isocapnic hypoxia (20 min) was maintained by end-tidal forcing, blood flow through IPAVA was determined by agitated saline contrast echocardiography and PASP was estimated by Doppler ultrasound. Arterial blood samples were collected at rest before each isocapnic-hypoxia condition to determine pH, [HCO3(-)] and Pa,CO2. AZ decreased pH (-0.08 ± 0.01), [HCO3(-)] (-7.1 ± 0.7 mmol l(-1)) and Pa,CO2 (-4.5 ± 1.4 mmHg; P < 0.01), while intravenous NaHCO3 restored arterial blood gas parameters to control levels. Although PASP increased from baseline in all three hypoxic conditions (P < 0.05), a main effect of condition expressed an 11 ± 2% reduction in PASP from control (P < 0.001) following AZ administration while intravenous NaHCO3 partially restored the PASP response to isocapnic hypoxia. Blood flow through IPAVA increased during exposure to isocapnic hypoxia (P < 0.01) and was unrelated to PASP, cardiac output and pulmonary vascular resistance for all conditions. In conclusion, isocapnic hypoxia induces blood flow through IPAVA independent of changes in PASP and the influence of AZ on the PASP response to isocapnic hypoxia is dependent upon the H(+) concentration or Pa,CO2.

Estimation of cardiac output and pulmonary vascular resistance by contrast echocardiography transit time measurement: a prospective pilot study

Background

Studies with other imaging modalities have demonstrated a relationship between contrast transit and cardiac output (CO) and pulmonary vascular resistance (PVR). We tested the hypothesis that the transit time during contrast echocardiography could accurately estimate both CO and PVR compared to right heart catheterization (RHC).

Methods

27 patients scheduled for RHC had 2D-echocardiogram immediately prior to RHC. 3 ml of DEFINITY contrast followed by a 10 ml saline flush was injected, and a multi-cycle echo clip was acquired from the beginning of injection to opacification of the left ventricle. 2D-echo based calculations of CO and PVR along with the DEFINITY-based transit time calculations were subsequently correlated with the RHC-determined CO and PVR.

Results

The transit time from full opacification of the right ventricle to full opacification of the left ventricle inversely correlated with CO (r = -0.61, p < 0.001). The transit time from peak opacification of the right ventricle to first appearance in the left ventricle moderately correlated with PVR (r = 0.46, p < 0.01). Previously described echocardiographic methods for the determination of CO (Huntsman method) and PVR (Abbas and Haddad methods) did not correlate with RHC-determined values (p = 0.20 for CO, p = 0.18 and p = 0.22 for PVR, respectively). The contrast transit time method demonstrated reliable intra- (p < 0.0001) and inter-observer correlation (p < 0.001).

Conclusions

We describe a novel method for the quantification of CO and estimation of PVR using contrast echocardiography transit time. This technique adds to the methodologies used for noninvasive hemodynamic assessment, but requires further validation to determine overall applicability.

Non-invasive estimation of pulmonary vascular resistance in patients of pulmonary hypertension in congenital heart disease with unobstructed pulmonary flow

Context:

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease accompanied by pulmonary arterial hypertension.

Aim:

The present study was planned to evaluate non-invasive echocardiographic parameters to assess pulmonary vascular resistance.

Settings and Design:

This prospective observational study included 44 patients admitted in the cardiology and pediatric cardiology ward of our institution for diagnostic or pre-operative catheter based evaluation of pulmonary arterial pressure and PVR.

Materials and Methods:

Detailed echocardiographic evaluation was carried out including tricuspid regurgitation velocity (TRV) and velocity time integral of the right-ventricular outflow tract (VTI_RVOT). These parameters were correlated with catheter-based measurements of PVR.

Results:

The TRV/VTI_RVOT ratio correlated well with PVR measured at catheterization (PVRcath) (r = 0.896, 95% confidence interval [CI] 0.816 to 0.9423, P < 0.001). Using the Bland-Altman analysis, PVR measurements derived from Doppler data showed satisfactory limits of agreement with catheterization estimated PVR. For a PVR of 6 Wood units (WU), a TRV/VTI_RVOT value of 0.14 provided a sensitivity of 96.67% and a specificity of 92.86% (area under the curve 0.963, 95% confidence interval 0.858 to 0.997) and for PVR of 8 WU a TRV/VTI_RVOT value of 0.17 provided a sensitivity of 79.17% and a specificity of 95% (area under the curve 0. 0.923, 95% confidence interval 0.801 to 0.982).

Conclusions:

Doppler-derived ratio of TRV/VTI_RVOT is a simple, non-invasive index, which can be used to estimate PVR.

Resting pulmonary haemodynamics and shunting: a comparison of sea-level inhabitants to high altitude Sherpas

The incidence of blood flow through intracardiac shunt and intrapulmonary arteriovenous anastomoses (IPAVA) may differ between Sherpas permanently residing at high altitude (HA) and sea-level (SL) inhabitants as a result of evolutionary pressure to improve gas exchange and/or resting pulmonary haemodynamics. To test this hypothesis we compared sea-level inhabitants at SL (SL-SL; n = 17), during acute isocapnic hypoxia (SL-HX; n = 7) and following 3 weeks at 5050 m (SL-HA; n = 8 non-PFO subjects) to Sherpas at 5050 m (n = 14). SpO2, heart rate, pulmonary artery systolic pressure (PASP) and cardiac index (Qi) were measured during 5 min of room air breathing at SL and HA, during 20 min of isocapnic hypoxia (SL-HX; PETO2 = 47 mmHg) and during 5 min of hyperoxia (FIO2 = 1.0; Sherpas only). Intracardiac shunt and IPAVA blood flow was evaluated by agitated saline contrast echocardiography. Although PASP was similar between groups at HA (Sherpas: 30.0 ± 6.0 mmHg; SL-HA: 32.7 ± 4.2 mmHg; P = 0.27), it was greater than SL-SL (19.4 ± 2.1 mmHg; P < 0.001). The proportion of subjects with intracardiac shunt was similar between groups (SL-SL: 41%; Sherpas: 50%). In the remaining subjects, IPAVA blood flow was found in 100% of subjects during acute isocapnic hypoxia at SL, but in only 4 of 7 Sherpas and 1 of 8 SL-HA subjects at rest. In conclusion, differences in resting pulmonary vascular regulation, intracardiac shunt and IPAVA blood flow do not appear to account for any adaptation to HA in Sherpas. Despite elevated pulmonary pressures and profound hypoxaemia, IPAVA blood flow in all subjects at HA was lower than expected compared to acute normobaric hypoxia.

A simple echocardiographic method to estimate pulmonary vascular resistance

Pulmonary hypertension includes heterogeneous diagnoses with distinct hemodynamic pathophysiologic features. Identifying elevated pulmonary vascular resistance (PVR) is critical for appropriate treatment. We reviewed data from patients seen at referral pulmonary hypertension clinics who had undergone echocardiography and right-side cardiac catheterization within 1 year. We derived equations to estimate PVR using the ratio of estimated pulmonary artery (PA) systolic pressure (PASPDoppler) to right ventricular outflow tract velocity time integral (VTI). We validated these equations in a separate sample and compared them with a published model based on the ratio of the transtricuspid flow velocity to right ventricular outflow tract VTI (model 1, Abbas et al 2003). The derived models were as follows: PVR = 1.2 × (PASP/right ventricular outflow tract VTI) (model 2) and PVR = (PASP/right ventricular outflow tract VTI) + 3 if notch present (model 3). The cohort included 217 patients with mean PA pressure of 45.3 ± 11.9 mm Hg, PVR of 7.3 ± 5.0 WU, and PA wedge pressure of 14.8 ± 8.1 mm Hg. Just >1/3 had a PA wedge pressure >15 mm Hg (35.5%) and 82.0% had PVR >3 WU. Model 1 systematically underestimated catheterization estimated PVR, especially for those with high PVR. The derived models demonstrated no systematic bias. Model 3 correlated best with PVR (r = 0.80 vs r = 0.73 and r = 0.77 for models 1 and 2, respectively). Model 3 had superior discriminatory power for PVR >3 WU (area under the curve 0.946) and PVR >5 WU (area under the curve 0.924), although all models discriminated well. Model 3-estimated PVR >3 was 98.3% sensitive and 61.1% specific for PVR >3 WU (positive predictive value 93%; negative predictive value 88%). In conclusion, we present an equation to estimate the PVR, using the ratio of PASPDoppler to right ventricular outflow tract VTI and a constant designating presence of right ventricular outflow tract VTI midsystolic notching, which provides superior agreement with catheterization estimates of PVR across a wide range of values.

Risk of death and need for transplantation in chronic pulmonary hypertension

BACKGROUND

Echo-Doppler parameters that exemplify right ventricular (RV) outflow dynamics and measures of annular tissue Doppler imaging to assess left ventricular (LV) and RV diastolic function, known to be affected in chronic pulmonary hypertension (cPH), have never been studied to determine if they could be predictive of mortality or need for transplantation 1-year after follow-up.

METHODS

Numerous echo-Doppler parameters of RV and LV performance were recorded from 120 patients. This patient population was divided into 3 groups. Group I had no PH, group II had cPH but no documented death or need for either lung or heart transplantation, at 1-year follow-up after their initial echocardiogram whereas group III had cPH and patients had either died or required heart and/or lung transplantation during the same time period.

RESULTS

Analysis of variance was first used to identify which echo-Doppler variables were significant among the studied groups. A logistic regression analysis was then performed to identify predictive variables of the occurrence death and need for transplantation. Finally, a multiple regression analysis was used between groups II and III to identify which echo-Doppler variables were most useful in identifying severe cPH patients at risk of the prespecified events.

CONCLUSIONS

Even though older patients with worse RV fractional area change might be considered at risk of worse prognosis in patients with severe cPH, only a low mitral annular early diastolic velocity was useful in identifying which of those individuals were at highest risk of death or in need of transplantation.

Hereditary hemorrhagic telangiectasia, liver vascular malformations and cardiac consequences

BACKGROUND

HHT patients with liver vascular malformations (VMs) may develop high-output cardiac failure requiring liver transplant in few cases.

OBJECTIVE

Our aim is to show that echocardiography is a good tool to evaluate the severity of hepatic vascular malformations in HHT and can improve medical management in HHT patients.

METHODS

The study is a cross-sectional study of cardiac parameters in HHT patients with dyspnea in a single referral center. All HHT patients with dyspnea, consecutively seen at HHT reference center in Lyon between May 2007 and November 2009 were included and had hepatic vascular Ultrasound and Echocardiography. Echocardiographic measures included cardiac output (CO) and index (CI), left ventricle (LV) filling pressures, and pulmonary artery pressure. Then, patients were classified in 4 groups according to the severity: group 1 (normal values), group 2 with isolated high CI, group 3 with high CI and increased LV-filling pressures and group 4 with increased LV-filling pressures and pulmonary hypertension.

RESULTS

Fifty-two HHT-patients were analyzed. Eight patients were in group 1, 25 in group 2, 6 in group 3 and 13 in group 4. Age, NYHA class dyspnea, edema, atrial fibrillation, hepatic artery diameter, and BNP (brain natriuretic peptide) levels significantly increased from groups 1 to 4 as well as left atrial area, and presence of mitral regurgitation. Patients with associated pulmonary VMs (n=11) did not show any clinical or echocardiographic differences.

CONCLUSION

Performing echocardiography in HHT patients with dyspnea allowed us to better understand the physiological processes of high-CO failure complicating liver vascular malformations and may improve follow-up of patients and treatment decisions.

MDCT-based quantification of porcine pulmonary arterial morphometry and self-similarity of arterial branching geometry

The pig is frequently used as an experimental model for studies of the pulmonary circulation, yet the branching and dimensional geometry of the porcine pulmonary vasculature remains poorly defined. The purposes of this study are to improve the geometric definition of the porcine pulmonary arteries and to determine whether the arterial tree exhibits self-similarity in its branching geometry. Five animals were imaged using thin slice spiral computed tomography in the prone posture during airway inflation pressure at 25 cmH2O. The luminal diameter and distance from the inlet of the left and right pulmonary arteries were measured along the left and right main arterial pathway in each lung of each animal. A further six minor pathways were measured in a single animal. The similarity in the rate of reduction of diameter with distance of all minor pathways and the two main pathways, along with similarity in the number of branches arising along the pathways, supports self-similarity in the arterial tree. The rate of reduction in diameter with distance from the inlet was not significantly different among the five animals (P > 0.48) when normalized for main pulmonary artery diameter and total main artery pathlength, which supports intersubject similarity. Other metrics to quantify the tree geometry are strikingly similar to those from airways of other quadrupeds, with the exception of a significantly larger length to diameter ratio, which is more appropriate for the vascular tree. A simplifying self-similar model for the porcine pulmonary arteries is proposed to capture the important geometric features of the arterial tree.

Clinical and echocardiographic correlations of exercise-induced pulmonary hypertension in systemic sclerosis: a multicenter study

BACKGROUND

Patients with systemic sclerosis (SSc) are at risk for developing pulmonary hypertension, which is associated with a poor prognosis. Exercise Doppler echocardiography enables the identification of exercise-induced increase in pulmonary artery systolic pressure (PASP) and may provide a thorough noninvasive hemodynamic evaluation.

AIM

The aim of this study was to evaluate the clinical and echocardiographic determinants of exercise-induced increase in PASP in a large population of patients with SSc.

METHODS

We selected 164 patients with SSc (age 58 ± 13 years, 91% female) with normal resting PASP (<40 mm Hg) who underwent a comprehensive 2-dimensional and Doppler echocardiography and graded bicycle semisupine exercise Doppler echocardiography. Pulmonary artery systolic pressure, cardiac output, and pulmonary vascular resistance (PVR) were estimated noninvasively. Cutoff values of PASP ≥50 mm Hg and PVR ≥3.0 Wood Units at peak exercise were considered a significant exercise-induced increase in PASP and PVR, respectively.

RESULTS

Sixty-nine (42%) patients showed a significant exercise-induced increase in PASP. Among them, peak PVR ≥3 Wood Units was present only in 11% of patients, about 5% of the total population. Univariate analysis showed that age, presence of interstitial lung disease, and both right and left diastolic dysfunction are predictors of peak PASP ≥50 mm Hg, but none of these parameters predict elevated peak PVR.

CONCLUSIONS

Exercise-induced increase in PASP occurs in almost one-half of patients with SSc with normal resting PASP. Peak exercise PASP is affected by age, interstitial lung disease, and right and left ventricular diastolic dysfunction and, only in 5% of the patients, is associated with an increase in PVR during exercise, suggesting heterogeneity of the mechanisms underlying exercise-induced pulmonary hypertension in SSc.

Right ventricular outflow tract systolic excursion: a distinguishing echocardiographic finding in acute pulmonary embolism

BACKGROUND

Even though chronic pulmonary hypertension (cPH) and acute pulmonary embolism (aPE) increase pulmonary vascular resistance and result in right ventricular (RV) dilatation and systolic dysfunction; both conditions operate through drastically different mechanisms. Unfortunately, simple echocardiographic examination might be insufficient to distinguish both entities. This study attempted to determine which objective measures would be useful in differentiating aPE from cPH.

METHODS

Standard measures of main RV as well as RV outflow tract (RVOT) size and systolic performance calculations were retrospectively measured from 15 patients with confirmed aPE by chest computed tomography and compared with similar data collected from the same number of age-matched patients with moderate (mcPH), severe (scPH), and patients without PH.

RESULTS

Although a positive McConnell sign was seen in 60% of aPE patients and in 17% of the cPH patients, all aPE had a profound reduction in RVOT systolic excursion when compared with cPH patients. Furthermore, maximal tricuspid annular plane systolic excursion, velocity time integral of the RVOT ejection signal, end-systolic or end-diastolic RV to left ventricle (LV) dimension ratio were not useful to distinguish aPE from any of the 2 forms of cPH.

CONCLUSION

This study demonstrated that measurement of RVOT systolic excursion not only is feasible but also extremely useful in identifying aPE and it is particularly helpful in differentiating it from patients with either mcPH or scPH. This variable might be useful to estimate the global impairment in RV contractility and acute hemodynamic derangement seen in aPE.

Noninvasive assessment of elevated pulmonary vascular resistance in children with pulmonary hypertension secondary to congenital heart disease: A comparative study between five different Doppler indices

BACKGROUND

Pulmonary vascular resistance (PVR) is an important hemodynamic parameter in patients with congenital heart disease (CHD). Noninvasive estimation of PVR represents an attractive alternative to invasive measurements.

METHODS

The study included 175 patients with pulmonary hypertension (PH) secondary to CHD. All patients underwent full echocardiographic study and invasive hemodynamic measurements. The study population was then subdivided into four subgroups. Each of the following Doppler indices was measured in one of these four subgroups: peak tricuspid regurgitant velocity (TRV), the ratio of the TRV to the velocity time integral of the right ventricular outflow tract (TRV/TVIRVOT), peak velocity of tricuspid annular systolic motion (TSm), heart rate corrected acceleration time and infliction time of the proximal left pulmonary artery (ATc, InTc). The data obtained was correlated with invasive PVR measurement. An ROC curve analysis was done to generate cutoff points with the highest balanced sensitivity and specificity to predict PVR > 6WU/m(2). The receiver operating characteristics (ROC) curves were compared with each other to determine the most reliable cutoff point in predicting elevated PVR > 6WU/m(2).

RESULTS

There was a significant correlation between both the TRV and TSm and invasive measurement of PVR (r = -0.511, 0.387 and P value = 0.0002, 0.006 respectively). The TSm and TRV cutoff values were the most reliable to predict elevated PVR > 6 WU/m(2). A TSm cutoff value of ⩽16.16 cm/s provided the best balanced sensitivity (85.7%) and specificity (66.7%) to determine PVRCATH > 6 WU/m(2). A cutoff value less than 7.62 cm/s had 100% specificity to predict PVRCATH > 6 WU/m(2). A TRV cutoff value of >3.96 m/s provided the best balanced sensitivity (66.7%) and specificity (100%) to determine PVRCATH > 6 WU/m(2). Both TRV and TSm had the highest area under the ROC curve among the 5 DOPPLER indices studied.

CONCLUSION

Prediction of elevated PVR in children with PH secondary to CHD could be achieved noninvasively using a number of Doppler indices. Among the five Doppler indices examined in the current study, the peak TRV and the TSm of the lateral tricuspid annulus had the highest balanced sensitivity and specificity to predict PVRI > 6 WU/m(2).

Temporal differences in ejection between right and left ventricles in chronic pulmonary hypertension: a pulsed Doppler study

Chronic pulmonary hypertension (cPH) is known to alter right ventricular (RV) deformation and cause mechanical dyssynchrony. Since not all echocardiographic laboratories are equipped with sophisticated imaging tools, we decided to determine if Doppler would be useful to detect temporal differences between the ejection of the right and left ventricle (LV) as a result of cPH using pulsed outflow tract (RVOT and LVOT) spectral signals. Data was collected from 30 patients without PH (Group I: 53 ± 7 years and 31 ± 5 mmHg) and from 40 patients with cPH (Group II: 53 ± 13 years; P = NS and 82 ± 24 mmHg; P < 0.00001). Group II patients had a longer temporal delay from onset between RVOT and LVOT (23 ± 12 ms vs. 0 ± 0 ms; P < 0.0001) with a significantly shorter temporal difference between RVOT and LVOT spectral signals to reach maximum peak of ejection (27 ± 24 ms vs. 61 ± 23 ms; P < 0.0001) than Group I. In addition, Group II had a statistically lower RVOT VTI value (0.14 ± 0.05 cm vs. 0.17 ± 0.03 cm; P < 0.01). Our data seems to suggest that increasing severity of PH mainly affects ejection of the RV resulting in noticeable temporal alterations in both time of onset as well as time to reach maximum peak ejection between RV and LV. More studies are now required to determine the utility of obtaining these measurements prospectively in the follow-up and treatment of cPH patients.

Portopulmonary hypertension: from diagnosis to treatment

Portopulmonary hypertension is a form of pulmonary arterial hypertension that has gained interest in recent years with the development of liver transplantation techniques and new pulmonary vasodilator therapies. Portopulmonary hypertension is defined as pulmonary artery hypertension associated with portal hypertension with or without advanced hepatic disease. Echocardiography plays a major role in screening for portopulmonary hypertension but right heart catheterization remains the gold standard for diagnosis. The treatment of patients with portopulmonary hypertension consists of general measures that apply to all patients that carry the diagnosis of pulmonary hypertension and specific vasodilator therapies. These new therapies showed encouraging results in patients who would otherwise have a contraindication for liver transplantation. The review presents a summary of the current knowledge on the epidemiology, diagnosis, treatment and prognosis of patients with portopulmonary hypertension.

Ratio of right to left ventricular ejection: a pilot study using Doppler to detect interventricular dyssynchrony

BACKGROUND

Chronic pulmonary hypertension (cPH) is known to delay maximal right ventricular (RV) deformation, causing mechanical dyssynchrony, which previously has been identified only through the use of myocardial tissue Doppler imaging. However, alterations between RV and left ventricular (LV) ejection should be easily identified during routine echocardiographic examinations.

HYPOTHESIS

We hypothesized that assessment of differences in ejection fraction between left and right ventricles would be detected using pulsed Doppler.

METHODS

Standard echo and Doppler data were collected from 30 patients without PH (mean age, 53 ± 7 y; mean pulmonary artery systolic pressure [PASP], 31 ± 5 mm Hg) and from 40 patients with cPH (mean age, 53 ± 13 y, P not significant; mean PASP, 82 ± 24 mm Hg, P<0.00001). Temporal differences in the ejection of both ventricles were measured as the ratio of total duration of RV to LV outflow tract (RVOT and LVOT) pulsed Doppler signals.

RESULTS

A ratio (<0.99) of RVOT to LVOT total duration of ejection was found not only to be the best Doppler parameter to identify an abnormal pulmonary artery systolic pressure, with a 90% sensitivity and 100% specificity (area under the curve 0.958, P = 0.0001), but also identified differences in the temporal ejection between the 2 ventricles, or dyssynchrony, as a result of cPH.

CONCLUSIONS

The ratio of pulsed Doppler RV to LV total duration of ejection is easily obtainable and appears useful in identifying the presence of interventricular dyssynchrony in cPH patients. A prospective study is now required to determine if this Doppler ratio can identify minute changes in the ejection of both ventricles as a result of changes in disease status or response to PH therapy.

Multimodality imaging of anomalous pulmonary veins

Partial anomalous pulmonary venous connection (PAPVC) is an extremely rare congenital condition where one or more of the pulmonary veins are connected to the venous circulation. Although initially suspected with unexplained right ventricular enlargement on transthoracic echocardiography (TTE), cardiac MRI is able to delineate the anatomical variant. We present a case of a 65-year-old male diagnosed with left sided PAPVC using multimodality cardiac imaging.