Right ventricular dysfunction in chronic thromboembolic obstruction of the pulmonary artery: a pressure-volume study using the conductance catheter

Amelioration of right ventricular systolic function and stiffness in a patient with idiopathic pulmonary arterial hypertension treated with oral triple combination therapy

Right ventricular (RV) function is an important determinant of the prognosis in patients with pulmonary arterial hypertension (PAH). In the context of recent therapeutic progress, there is an increasing need for better monitoring of RV function for management of PAH. We present the case of a 42-year-old woman with idiopathic PAH who was treated with three oral pulmonary vasodilators, i.e. tadalafil, ambrisentan, and beraprost. At the baseline assessment, the mean pulmonary arterial pressure (mPAP) was 45 mmHg, cardiac index (CI) was 1.36 L/min/m², and pulmonary vascular resistance (PVR) was elevated to 21.3 Wood units (WU). However, three months after the start of combination treatment, mPAP and PVR decreased to 42 mmHg and 7.5 WU, respectively, and conventional indices of RV function, such as CI, right atrial area, and right atrial pressure also improved. Beyond three months, however, there were no further improvements in mPAP, PVR, or indices of RV function. In addition, we calculated three recently introduced indices of intrinsic RV function: end-systolic elastance (Ees; an index of RV contractility), Ees/arterial elastance ratio (Ees/Ea; an index of RV/pulmonary arterial coupling), and β (an index of RV stiffness) using cardiac magnetic resonance imaging and Swan-Ganz catheterization measurements. Notably, in contrast to conventional parameters, Ees, Ees/Ea, and β showed persistent improvement during the entire two-year follow-up. The application of Ees, Ees/Ea, and β may play an additional role in a comprehensive assessment of RV function in PAH.

Histologic and Hemodynamic Correlates of Right Ventricular Function in a Pressure Overload Model: a Study Using Three-Dimensional Speckle Tracking Echocardiography

The aim of our study was to assess the characterization of right ventricular (RV) deformation using three-dimensional (3D) speckle tracking echocardiography (STE) and association of 3D-STE indices with histologic and hemodynamic parameters in a chronic RV pressure overload animal model. Pulmonary artery banding (PAB) was used to induce RV pressure overload in seven beagles. 3D-STE, histologic and hemodynamic measurements were performed in PAB and sham-operated beagles 3 mo after PAB. RV longitudinal, radial and circumferential strain was measured from 3D-STE. Three mo after PAB, RV longitudinal strain was decreased; whereas radial and circumferential strain remained unchanged in PAB group. RV longitudinal strain was associated with interstitial fibrosis (r = -0.733) in the endocardial layer of the RV free wall. RV circumferential strain was related to dp/dt_max (r = 0.718). The significant correlations of RV 3D-STE indices with histologic and hemodynamic parameters indicate that 3D-STE may be a valuable tool for assessment of ventricular function in RV pressure overload.

Ventriculo-arterial coupling detects occult RV dysfunction in chronic thromboembolic pulmonary vascular disease

Chronic thromboembolic disease (CTED) is suboptimally defined by a mean pulmonary artery pressure (mPAP) <25 mmHg at rest in patients that remain symptomatic from chronic pulmonary artery thrombi. To improve identification of right ventricular (RV) pathology in patients with thromboembolic obstruction, we hypothesized that the RV ventriculo-arterial (Ees/Ea) coupling ratio at maximal stroke work (Ees/Ea_{max sw}) derived from an animal model of pulmonary obstruction may be used to identify occult RV dysfunction (low Ees/Ea) or residual RV energetic reserve (high Ees/Ea). Eighteen open chested pigs had conductance catheter RV pressure-volume (PV)-loops recorded during PA snare to determine Ees/Ea_{max sw} This was then applied to 10 patients with chronic thromboembolic pulmonary hypertension (CTEPH) and ten patients with CTED, also assessed by RV conductance catheter and cardiopulmonary exercise testing. All patients were then restratified by Ees/Ea. The animal model determined an Ees/Ea_{max sw} = 0.68 ± 0.23 threshold, either side of which cardiac output and RV stroke work fell. Two patients with CTED were identified with an Ees/Ea well below 0.68 suggesting occult RV dysfunction whilst three patients with CTEPH demonstrated Ees/Ea ≥ 0.68 suggesting residual RV energetic reserve. Ees/Ea > 0.68 and Ees/Ea < 0.68 subgroups demonstrated constant RV stroke work but lower stroke volume (87.7 ± 22.1 vs. 60.1 ± 16.3 mL respectively, P = 0.006) and higher end-systolic pressure (36.7 ± 11.6 vs. 68.1 ± 16.7 mmHg respectively, P < 0.001). Lower Ees/Ea in CTED also correlated with reduced exercise ventilatory efficiency. Low Ees/Ea aligns with features of RV maladaptation in CTED both at rest and on exercise. Characterization of Ees/Ea in CTED may allow for better identification of occult RV dysfunction.

Patient-Specific Computational Analysis of Ventricular Mechanics in Pulmonary Arterial Hypertension

Patient-specific biventricular computational models associated with a normal subject and a pulmonary arterial hypertension (PAH) patient were developed to investigate the disease effects on ventricular mechanics. These models were developed using geometry reconstructed from magnetic resonance (MR) images, and constitutive descriptors of passive and active mechanics in cardiac tissues. Model parameter values associated with ventricular mechanical properties and myofiber architecture were obtained by fitting the models with measured pressure-volume loops and circumferential strain calculated from MR images using a hyperelastic warping method. Results show that the peak right ventricle (RV) pressure was substantially higher in the PAH patient (65 mmHg versus 20 mmHg), who also has a significantly reduced ejection fraction (EF) in both ventricles (left ventricle (LV): 39% versus 66% and RV: 18% versus 64%). Peak systolic circumferential strain was comparatively lower in both the left ventricle (LV) and RV free wall (RVFW) of the PAH patient (LV: -6.8% versus -13.2% and RVFW: -2.1% versus -9.4%). Passive stiffness, contractility, and myofiber stress in the PAH patient were all found to be substantially increased in both ventricles, whereas septum wall in the PAH patient possessed a smaller curvature than that in the LV free wall. Simulations using the PAH model revealed an approximately linear relationship between the septum curvature and the transseptal pressure gradient at both early-diastole and end-systole. These findings suggest that PAH can induce LV remodeling, and septum curvature measurements may be useful in quantifying transseptal pressure gradient in PAH patients.

Pulmonary Hypertension in Heart Failure: Pathophysiology, Pathobiology, and Emerging Clinical Perspectives

Pulmonary hypertension is a common hemodynamic complication of heart failure. Interest in left-sided pulmonary hypertension has increased remarkably in recent years because its development and consequences for the right heart are now seen as mainstay abnormalities that begin in the early stages of the disease and bear unfavorable prognostic insights. However, some knowledge gaps limit our ability to influence this complex condition. Accordingly, attention is now focused on: 1) establishing a definitive consensus for a hemodynamic definition, perhaps incorporating exercise and fluid challenge; 2) implementing the limited data available on the pathobiology of lung capillaries and small arteries; 3) developing standard methods for assessing right ventricular function and, hopefully, its coupling to pulmonary circulation; and 4) searching for effective therapies that may benefit lung vessels and the remodeled right ventricle. The authors review the pathophysiology, pathobiology, and emerging clinical perspectives on pulmonary hypertension across the broad spectrum of heart failure stages.

Assessing right ventricular function in pulmonary hypertension patients and the correlation with the New York Heart Association (NYHA) classification

This investigation aimed to compare the pressure-volume loop (PV loop) measurements in three less symptomatic categories (New York Heart Association classes , NYHA I, II, and III) of pulmonary hypertension (PH) patients since NYHA classification system performance is limited by the shortcomings discussed above.

Thirty-six patients were enrolled in this study with PV loop measurement acquisition via micro-conductance catheters. Functional classification according to NYHA was determined with comprehensive assessing function and activity. Catheterization and MRI was applied to obtain variables on right ventricle (RV) functions. Correlation test was applied to test the relationship between measured PV loop measurements and NYHA classification.

A group of PV loop measurements, including end-systolic pressure (RVESP) RV end-diastolic pressure (RVEDP), and RV arterial elastance (RVEa), are well correlated with three NYHA classes (I, II, and III). Moreover, RVESP and RVEa significantly correlated with two groups of NYHA classes (I and II/III) while RVEDP, RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) significantly moderately correlated with two groups of NYHA classes (I/II and III). This study suggests the promising role of PV loop analysis in assessing functional capacity in progressive but less symptomatic PH patients.

Stunning and Right Ventricular Dysfunction Is Induced by Coronary Balloon Occlusion and Rapid Pacing in Humans: Insights From Right Ventricular Conductance Catheter Studies

Background

We sought to determine whether right ventricular stunning could be detected after supply (during coronary balloon occlusion [BO]) and supply/demand ischemia (induced by rapid pacing [RP] during transcatheter aortic valve replacement) in humans.

Methods and Results

Ten subjects with single‐vessel right coronary artery disease undergoing percutaneous coronary intervention with normal ventricular function were studied in the BO group. Ten subjects undergoing transfemoral transcatheter aortic valve replacement were studied in the RP group. In both, a conductance catheter was placed into the right ventricle, and pressure volume loops were recorded at baseline and for intervals over 15 minutes after a low‐pressure BO for 1 minute or a cumulative duration of RP for up to 1 minute. Ischemia‐induced diastolic dysfunction was seen 1 minute after RP (end‐diastolic pressure [mm Hg]: 8.1±4.2 versus 12.1±4.1, P<0.001) and BO (end‐diastolic pressure [mm Hg]: 8.1±4.0 versus 8.7±4.0, P=0.03). Impairment of systolic and diastolic function after BO remained at 15‐minutes recovery (ejection fraction [%]: 55.7±9.0 versus 47.8±6.3, P<0.01; end‐diastolic pressure [mm Hg]: 8.1±4.0 versus 9.2±3.9, P<0.01). Persistent diastolic dysfunction was also evident in the RP group at 15‐minutes recovery (end‐diastolic pressure [mm Hg]: 8.1±4.1 versus 9.9±4.4, P=0.03) and there was also sustained impairment of load‐independent indices of systolic function at 15 minutes after RP (end‐systolic elastance and ventriculo‐arterial coupling [mm Hg/mL]: 1.25±0.31 versus 0.85±0.43, P<0.01).

Conclusions

RP and right coronary artery balloon occlusion both cause ischemic right ventricular dysfunction with stunning observed later during the procedure. This may have intraoperative implications in patients without right ventricular functional reserve.

Prostacyclins have no direct inotropic effect on isolated atrial strips from the normal and pressure-overloaded human right heart

Prostacyclins are vasodilatory agents used in the treatment of pulmonary arterial hypertension. The direct effects of prostacyclins on right heart function are still not clarified. The aim of this study was to investigate the possible direct inotropic properties of clinical available prostacyclin mimetics in the normal and the pressure-overloaded human right atrium. Trabeculae from the right atrium were collected during surgery from chronic thromboembolic pulmonary hypertension (CTEPH) patients with pressure-overloaded right hearts, undergoing pulmonary thromboendarterectomy (n = 10) and from patients with normal right hearts operated by valve replacement or coronary bypass surgery (n = 9). The trabeculae were placed in an organ bath, continuously paced at 1 Hz. They were subjected to increasing concentrations of iloprost, treprostinil, epoprostenol, or MRE-269, followed by isoprenaline to elicit a reference inotropic response. The force of contraction was measured continuously. The expression of prostanoid receptors was explored through quantitative polymerase chain reaction (qPCR).

Iloprost, treprostinil, epoprostenol, or MRE-269 did not alter force of contraction in any of the trabeculae. Isoprenaline showed a direct inotropic response in both trabeculae from the pressure-overloaded right atrium and from the normal right atrium. Control experiments on ventricular trabeculae from the pig failed to show an inotropic response to the prostacyclin mimetics. qPCR demonstrated varying expression of the different prostanoid receptors in the human atrium. In conclusion, prostacyclin mimetics did not increase the force of contraction of human atrial trabeculae from the normal or the pressure-overloaded right heart. These data suggest that prostacyclin mimetics have no direct inotropic effects in the human right atrium.

The pathophysiology of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, progressive pulmonary vascular disease that is usually a consequence of prior acute pulmonary embolism. CTEPH usually begins with persistent obstruction of large and/or middle-sized pulmonary arteries by organised thrombi. Failure of thrombi to resolve may be related to abnormal fibrinolysis or underlying haematological or autoimmune disorders. It is now known that small-vessel abnormalities also contribute to haemodynamic compromise, functional impairment and disease progression in CTEPH. Small-vessel disease can occur in obstructed areas, possibly triggered by unresolved thrombotic material, and downstream from occlusions, possibly because of excessive collateral blood supply from high-pressure bronchial and systemic arteries. The molecular processes underlying small-vessel disease are not completely understood and further research is needed in this area. The degree of small-vessel disease has a substantial impact on the severity of CTEPH and postsurgical outcomes. Interventional and medical treatment of CTEPH should aim to restore normal flow distribution within the pulmonary vasculature, unload the right ventricle and prevent or treat small-vessel disease. It requires early, reliable identification of patients with CTEPH and use of optimal treatment modalities in expert centres.

Effects of exercise training on pulmonary hemodynamics, functional capacity and inflammation in pulmonary hypertension

Pulmonary hypertension (PH) is characterized by severe exercise limitation mainly attributed to the impairment of right ventricular function resulting from a concomitant elevation of pulmonary vascular resistance and pressure. The unquestioned cornerstone in the management of patients with pulmonary arterial hypertension (PAH) is specific vasoactive medical therapy to improve pulmonary hemodynamics and strengthen right ventricular function. Nevertheless, evidence for a beneficial effect of exercise training (ET) on pulmonary hemodynamics and functional capacity in patients with PH has been growing during the past decade. Beneficial effects of ET on regulating factors, inflammation, and metabolism have also been described. Small case-control studies and randomized clinical trials in larger populations of patients with PH demonstrated substantial improvements in functional capacity after ET. These findings were accompanied by several studies that suggested an effect of ET on inflammation, although a direct link between this effect and the therapeutic benefit of ET in PH has not yet been demonstrated. On this background, the aim of the present review is to describe current concepts regarding the effects of exercise on the pulmonary circulation and pathophysiological limitations, as well as the clinical and mechanistic effects of exercise in patients with PH.

Venous thromboembolism and subsequent permanent work-related disability

Essentials The burden of venous thromboembolism (VTE) related to permanent work-related disability is unknown. In a cohort of 66 005 individuals, the risk of work-related disability after a VTE was assessed. Unprovoked VTE was associated with 52% increased risk of work-related disability. This suggests that indirect costs due to loss of work time may add to the economic burden of VTE.

SUMMARY

Background The burden of venous thromboembolism (VTE) related to permanent work-related disability has never been assessed among a general population. Therefore, we aimed to estimate the risk of work-related disability in subjects with incident VTE compared with those without VTE in a population-based cohort. Methods From the Tromsø Study and the Nord-Trøndelag Health Study (HUNT), Norway, 66 005 individuals aged 20-65 years were enrolled in 1994-1997 and followed to 31 December 2008. Incident VTE events among the study participants were identified and validated, and information on work-related disability was obtained from the Norwegian National Insurance Administration database. Cox-regression models using age as time-scale and VTE as time-varying exposure were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for sex, body mass index, smoking, education level, marital status, history of cancer, diabetes, cardiovascular disease and self-rated general health. Results During follow-up, 384 subjects had a first VTE and 9862 participants were granted disability pension. The crude incidence rate of work-related disability after VTE was 37.5 (95% CI, 29.7-47.3) per 1000 person-years, vs. 13.5 (13.2-13.7) per 1000 person-years among those without VTE. Subjects with unprovoked VTE had a 52% higher risk of work-related disability than those without VTE (HR, 1.52; 95% CI, 1.09-2.14) after multivariable adjustment, and the association appeared to be driven by deep vein thrombosis. Conclusion VTE was associated with subsequent work-related disability in a cohort recruited from the general working-age population. Our findings suggest that indirect costs because of loss of work time may add to the economic burden of VTE.

Hemodynamic and ventilatory responses during exercise in chronic thromboembolic disease

BACKGROUND

Patients with chronic thromboembolic disease (CTED) may suffer from exercise intolerance without pulmonary hypertension at rest. Pulmonary endarterectomy (PEA) for symptomatic CTED results in improvement of symptoms and quality of life. Neither the pathophysiology of the exercise limitation nor the underlying mechanisms of the PEA-induced improvement have been studied previously.

OBJECTIVES

We studied hemodynamic and ventilatory responses upon exercise in 14 patients with CTED. After 1 year, we studied the underlying physiologic mechanisms of the PEA-induced symptomatic improvement.

METHODS

Cardiopulmonary exercise testing (CPET) was performed during right heart catheterization, and noninvasive CPET was performed 1 year postoperatively.

RESULTS

During exercise, we observed abnormal pulmonary vascular responses, that is, a steep mean pulmonary artery pressure/cardiac output (2.7 ± 1.2 mm Hg·min·L(-1)), and low pulmonary vascular compliance (2.8 ± 1.1 mL·mm Hg(-1)); mean pulmonary artery pressure/cardiac output slope correlated with dead-space ventilation (r = 0.586; P = .028) and ventilatory equivalents for carbon dioxide slope (r = .580; P = .030). Postoperatively, the improvement observed in exercise capacity was related to improvements in CPET-derived parameters pointing to restoration of right ventricle stroke volume response (oxygen pulse: 11.7 ± 3.1 to 13.3 ± 3.3; P = .027; heart rate response: 80.9 ± 12.4 to 72.0 ± 5.7; P = .003); and, indicating improved ventilatory efficiency, the ventilatory equivalents for carbon dioxide slope decreased from 38.2 ± 3.6 to 32.8 ± 7.0 (P = .014).

CONCLUSIONS

Patients with CTED showed an abnormal pulmonary vascular response to exercise and a decreased ventilatory efficiency. Responses after PEA point to restoration of right ventricle stroke volume response and ventilatory efficiency.

Imaging right ventricular function to predict outcome in pulmonary arterial hypertension

BACKGROUND

Right ventricular (RV) function is a major determinant of outcome in pulmonary arterial hypertension (PAH). However, uncertainty persists about the optimal method of evaluation.

METHODS

We measured RV end-systolic and end-diastolic volumes (ESV and EDV) using cardiac magnetic resonance imaging and RV pressures during right heart catheterization in 140 incident PAH patients and 22 controls. A maximum RV pressure (Pmax) was calculated from the nonlinear extrapolations of early and late systolic portions of the RV pressure curve. The gold standard measure of RV function adaptation to afterload, or RV-arterial coupling (Ees/Ea) was estimated by the stroke volume (SV)/ESV ratio (volume method) or as Pmax/mean pulmonary artery pressure (mPAP) minus 1 (pressure method) (n=84). RV function was also assessed by ejection fraction (EF), right atrial pressure (RAP) and SV.

RESULTS

Higher Ea and RAP, and lower compliance, SV and EF predicted outcome at univariate analysis. Ees/Ea estimated by the pressure method did not predict outcome but Ees/Ea estimated by the volume method (SV/ESV) did. At multivariate analysis, only SV/ESV and EF were independent predictors of outcome. Survival was poorer in patients with a fall in EF or SV/ESV during follow-up (n=44, p=0.008).

CONCLUSION

RV function to predict outcome in PAH is best evaluated by imaging derived SV/ESV or EF. In this study, there was no added value of invasive measurements or simplified pressure-derived estimates of RV-arterial coupling.

RV diastolic dysfunction: time to re-evaluate its importance in heart failure

Right ventricular (RV) diastolic dysfunction was first reported as an indicator for the assessment of ventricular dysfunction in heart failure a little over two decades ago. However, the underlying mechanisms and precise role of RV diastolic dysfunction in heart failure remain poorly described. Complexities in the structure and function of the RV make the detailed assessment of the contractile performance challenging when compared to its left ventricular (LV) counterpart. LV dysfunction is known to directly affect patient outcome in heart failure. As such, the focus has therefore been on LV function. Nevertheless, a strategy for the diagnosis and assessment of RV diastolic dysfunction has not been established. Here, we review the different causal mechanisms underlying RV diastolic dysfunction, summarising the current assessment techniques used in a clinical environment. Finally, we explore the role of load-independent indices of RV contractility, derived from the conductance technique, to fully interrogate the RV and expand our knowledge and understanding of RV diastolic dysfunction. Accurate assessment of RV contractility may yield further important prognostic information that will benefit patients with diastolic heart failure.

Developments in pulmonary arterial hypertension-targeted therapy for chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease characterised by the presence of organised chronic thromboembolic material occluding the proximal pulmonary arteries and a vasculopathy in the distal pulmonary arterial tree. Pulmonary endarterectomy (PEA) is a potential cure for many patients with CTEPH. However, PEA is not suitable for patients with a significant distal distribution of chronic thromboembolic material or with significant comorbidities. Also, a proportion of patients are left with residual CTEPH post PEA. Until recently, pulmonary arterial hypertension-targeted therapies have been used off licence to treat patients with inoperable or residual CTEPH. The CHEST1 study investigated the use of riociguat and was the first randomised controlled trial to show efficacy in inoperable or residual CTEPH. In this review, we explore the pathophysiology of CTEPH and review the current trial evidence for pulmonary arterial hypertension-targeted therapies. We also include a discussion of physiological considerations that require further investigation.

The right ventricle in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a right heart failure syndrome. In early-stage PAH, the right ventricle tends to remain adapted to afterload with increased contractility and little or no increase in right heart chamber dimensions. However, less than optimal right ventricular (RV)-arterial coupling may already cause a decreased aerobic exercise capacity by limiting maximum cardiac output. In more advanced stages, RV systolic function cannot remain matched to afterload and dilatation of the right heart chamber progressively develops. In addition, diastolic dysfunction occurs due to myocardial fibrosis and sarcomeric stiffening. All these changes lead to limitation of RV flow output, increased right-sided filling pressures and under-filling of the left ventricle, with eventual decrease in systemic blood pressure and altered systolic ventricular interaction. These pathophysiological changes account for exertional dyspnoea and systemic venous congestion typical of PAH. Complete evaluation of RV failure requires echocardiographic or magnetic resonance imaging, and right heart catheterisation measurements. Treatment of RV failure in PAH relies on: decreasing afterload with drugs targeting pulmonary circulation; fluid management to optimise ventricular diastolic interactions; and inotropic interventions to reverse cardiogenic shock. To date, there has been no report of the efficacy of drug treatments that specifically target the right ventricle.

The role of elastic restoring forces in right-ventricular filling

AIMS

The physiological determinants of RV diastolic function remain poorly understood. We aimed to quantify the contribution of elastic recoil to RV filling and determine its sensitivity to interventricular interaction.

METHODS AND RESULTS

High-fidelity pressure-volume loops and simultaneous 3-dimensional ultrasound sequences were obtained in 13 pigs undergoing inotropic modulation, volume overload, and acute pressure overload induced by endotoxin infusion. Using a validated method, we isolated elastic restoring forces from ongoing relaxation using conventional pressure-volume data. The RV contracted below the equilibrium volume in >75% of the data sets. Consequently, elastic recoil generated strong sub-atmospheric passive pressure at the onset of diastole [-3 (-4 to -2) mmHg at baseline]. Stronger restoring suction pressure was related to a shorter isovolumic relaxation period, a higher rapid filling fraction, and lower atrial pressures (all P < 0.05). Restoring forces were mostly determined by the position of operating volumes around the equilibrium volume. By this mechanism, the negative inotropic effect of beta-blockade reduced and sometimes abolished restoring forces. During acute pressure overload, restoring forces initially decreased, but recovered at advanced stages. This biphasic response was related to alterations of septal curvature induced by changes in the diastolic LV-RV pressure balance. The constant of elastic recoil was closely related to the constant of passive stiffness (R = 0.69).

CONCLUSION

The RV works as a suction pump, exploiting contraction energy to facilitate filling by means of strong elastic recoil. Restoring forces are influenced by the inotropic state and RV conformational changes mediated by direct ventricular interdependence.

Right ventricle in acute and chronic pulmonary embolism (2013 Grover Conference series)

Venous thromboembolism (VTE) encompasses deep-vein thrombosis and pulmonary embolism (PE). It is the third-most-frequent cardiovascular disease, with an overall annual incidence of 1-2 per 1,000 population. Chronic thromboembolic pulmonary hypertension (CTEPH) is regarded as a late sequela of PE, with a reported incidence varying between 0.1% and 9.1% of those surviving acute VTE. Right ventricular (RV) function is dependent on afterload. The most precise technique to describe RV function is invasive assessment of the RV-to-pulmonary vascular coupling. However, assessments of RV afterload (i.e., steady and pulsatile flow components and their product, the RC-time) may be useful hemodynamic surrogates of coupling. RV load is different in acute and chronic PE. In acute PE, more than 60% occlusion of the cross-sectional area of the pulmonary artery within a short period of time leads to abrupt hemodynamic collapse. If the time of occlusion is limited to ∼15 seconds, significant decreases in fractional area change, tricuspid annulus systolic excursion, and RV free-wall deformation (strain) occur, with the latter showing significant postsystolic shortening. These changes have similarities to ischemic stunning, and they recover within minutes. In CTEPH, studies of pulmonary vascular resistance (PVR) and pulmonary arterial compliance demonstrated low RC-times that were further lowered after pulmonary endarterectomy (PEA). Immediate postoperative PVR was the only predictor of long-term survival/freedom from lung transplantation, suggesting that the effect of PEA on opening vascular territories to flow outweighs its effect on proximal stiffness. This review summarizes the current knowledge on vascular and intrinsic RV adaptation to VTE, including CTEPH, and the role of imaging.

RV-pulmonary arterial coupling predicts outcome in patients referred for pulmonary hypertension

OBJECTIVE

Prognosis in pulmonary hypertension (PH) is largely determined by RV function. However, uncertainty remains about what metrics of RV function might be most clinically relevant. The purpose of this study was to assess the clinical relevance of metrics of RV functional adaptation to increased afterload.

METHODS

Patients referred for PH underwent right heart catheterisation and RV volumetric assessment within 48 h. A RV maximum pressure (Pmax) was calculated from the RV pressure curve. The adequacy of RV systolic functional adaptation to increased afterload was estimated either by a stroke volume (SV)/end-systolic volume (ESV) ratio, a Pmax/mean pulmonary artery pressure (mPAP) ratio, or by EF (RVEF). Diastolic function of the RV was estimated by a diastolic elastance coefficient β. Survival analysis was via Cox proportional HR, and Kaplan-Meier with the primary outcome of time to death or lung transplant.

RESULTS

Patients (n=50; age 58±13 yrs) covered a range of mPAP (13-79 mm Hg) with an average RVEF of 39±17% and ESV of 143±89 mL. Average estimates of the ratio of end-systolic ventricular to arterial elastance were 0.79±0.67 (SV/ESV) and 2.3±0.65 (Pmax/mPAP-1). Transplantation-free survival was predicted by right atrial pressure, mPAP, pulmonary vascular resistance, β, SV, ESV, SV/ESV and RVEF, but after controlling for right atrial pressure, mPAP, and SV, SV/ESV was the only independent predictor.

CONCLUSIONS

The adequacy of RV functional adaptation to afterload predicts survival in patients referred for PH. Whether this can simply be evaluated using RV volumetric imaging will require additional confirmation.

Left ventricular diastolic function in hypertension: methodological considerations and clinical implications

The assessment of left ventricular (LV) diastolic function should be an integral part of a routine examination of hypertensive patient; indeed when LV diastolic function is impaired, it is possible to have heart failure even with preserved LV ejection fraction. Left ventricular diastolic dysfunction (LVDD) occurs frequently and is associated to heart disease. Doppler echocardiography is the best tool for early LVDD diagnosis. Hypertension affects LV relaxation and when left ventricular hypertrophy (LVH) occurs, it decreases compliance too, so it is important to calculate Doppler echocardiography parameters, for diastolic function evaluation, in all hypertensive patients. The purpose of our review was to discuss about the strong relationship between LVDD and hypertension, and their relationship with LV systolic function. Furthermore, we aimed to assess the relationship between the arterial stiffness and LV structure and function in hypertensive patients.

Outcome of pulmonary endarterectomy in symptomatic chronic thromboembolic disease

Chronic thromboembolic disease is characterised by persistent pulmonary thromboembolic occlusions without pulmonary hypertension. Early surgical treatment with pulmonary endarterectomy may improve symptoms and prevent disease progression. We sought to assess the outcome of pulmonary endarterectomy in symptomatic patients with chronic thromboembolic disease.

Patients with symptomatic chronic thromboembolic disease and a mean pulmonary artery pressure <25 mmHg at baseline with right heart catheterisation and treated with pulmonary endarterectomy between January 2000 and July 2013 were identified. Patients were reassessed at 6 months and at 1 year following surgery.

A total of 42 patients underwent surgery and the median length of stay in hospital was 11 days. There was no in-hospital mortality but complications occurred in 40% of patients. At 1 year, following surgery, 95% of the patients remained alive. There was a significant symptomatic improvement with 95% of patients in the New York Heart Association functional classes I or II at 6 months. There was a significant improvement in quality of life assessed by the Cambridge pulmonary hypertension outcome review questionnaire.

In this carefully selected cohort of chronic thromboembolic disease patients, pulmonary endarterectomy resulted in significant improvement in symptoms and quality of life. Appropriate patient selection is paramount given the known surgical morbidity and mortality, and surgery should only be performed in expert centres.

Chronic thromboembolic pulmonary hypertension: time for research in pathophysiology to catch up with developments in treatment

The modern treatment era in chronic thromboembolic disease has seen significant advances in both surgical and medical treatment. One such treatment, the pulmonary endarterectomy (where established chronic organized thrombus is removed), has dramatically affected morbidity and mortality. These advances have outstripped basic research into the causes and pathophysiology of disease, which remain largely poorly understood. In this review, we will set out to explain some of the historical reasons for this, including the difficulties inherent in human studies and the lack of good animal models. We will review some of the recent advances in pathophysiology from registries and translational research, and we will summarize the treatment options, with some discussion of very recently published work, including medical and surgical treatments, both traditional and more experimental work in non-invasive techniques.