Progressive right ventricular enlargement due to pulmonary regurgitation: Clinical characteristics of a "low-risk" group

Right Heart Reverse Remodeling and Prosthetic Valve Function After Transcatheter vs Surgical Pulmonary Valve Replacement

BACKGROUND

There are limited data about postprocedural right heart reverse remodeling and long-term prosthesis durability after transcatheter pulmonary valve replacement (TPVR) and how these compare to surgical pulmonary valve replacement (SPVR).

OBJECTIVES

This study sought to compare right heart reverse remodeling, pulmonary valve gradients, and prosthetic valve dysfunction after TPVR vs SPVR.

METHODS

Patients with TPVR were matched 1:2 to patients with SPVR based on age, sex, body surface area, congenital heart lesion, and procedure year. Right heart indexes (right atrial [RA] reservoir strain, RA volume index, RA pressure, right ventricular [RV] global longitudinal strain, RV end-diastolic area, and RV systolic pressure) were assessed at baseline (preintervention), 1 year postintervention, and 3 years postintervention. Pulmonary valve gradients were assessed at 1, 3, 5, 7, and 9 years postintervention.

RESULTS

There were 64 and 128 patients in the TPVR and SPVR groups, respectively. Among patients with TPVR, 46 (72%) and 18 (28%) received Melody (Medtronic) vs SAPIEN (Edwards Lifesciences) valves, respectively. The TPVR group had greater postprocedural improvement in RA reservoir strain and RV global longitudinal strain at 1 and 3 years. The TPVR group had a higher risk of prosthetic valve dysfunction mostly because of a higher incidence of prosthetic valve endocarditis compared to SPVR but a similar risk of pulmonary valve reintervention because some of the patients with endocarditis received medical therapy only. Both groups had similar pulmonary valve mean gradients at 9 years postintervention.

CONCLUSIONS

These data suggest a more favorable right heart outcome after TPVR. However, the risk of prosthetic valve endocarditis and prosthetic valve dysfunction remains a major concern.

Effect of pulmonary regurgitation on cardiac functions based on a human bi-ventricle model

BACKGROUND AND OBJECTIVE

Assessing the severity of pulmonary regurgitation (PR) and identifying optimal clinically relevant indicators for its treatment is crucial, yet standards for quantifying PR remain unclear in clinical practice. Computational modelling of the heart is in the process of providing valuable insights and information for cardiovascular physiology research. However, the advancements of finite element computational models have not been widely applied to simulate cardiac outputs in patients with PR. Furthermore, a computational model that incorporates both the left ventricle (LV) and right ventricle (RV) can be valuable in assessing the relationship between left and right ventricular morphometry and septal motion in PR patients. To enhance our understanding of the effect of PR on cardiac functions and mechanical behaviour, we developed a human bi-ventricle model to simulate five cases with varying degrees of PR severity.

METHODS

This bi-ventricle model was built using a patient-specific geometry and a widely used myofibre architecture. The myocardial material properties were described by a hyperelastic passive constitutive law and a modified time-varying elastance active tension model. To simulate realistic cardiac functions and the dysfunction of the pulmonary valve in PR disease cases, open-loop lumped parameter models representing systemic and pulmonary circulatory systems were designed.

RESULTS

In the baseline case, pressures in the aorta and main pulmonary artery and ejection fractions of both the LV and RV were within normal physiological ranges reported in the literature. The end-diastolic volume (EDV) of the RV under varying degrees of PR was comparable to the reported cardiac magnetic resonance imaging data. Moreover, RV dilation and interventricular septum motion from the baseline to the PR cases were clearly observed through the long-axis and short-axis views of the bi-ventricle geometry. The RV EDV in the severe PR case increased by 50.3% compared to the baseline case, while the LV EDV decreased by 18.1%. The motion of the interventricular septum was consistent with the literature. Furthermore, ejection fractions of both the LV and RV decreased as PR became severe, with LV ejection fraction decreasing from 60.5% at baseline to 56.3% in the severe case and RV ejection fraction decreasing from 51.8% to 46.8%. Additionally, the average myofibre stress of the RV wall at end-diastole significantly increased due to PR, from 2.7±12.1 kPa at baseline to 10.9±26.5 kPa in the severe case. The average myofibre stress of the LV wall at end-diastole increased from 3.7±18.1 kPa to 4.3±20.3 kPa.

CONCLUSIONS

This study established a foundation for the computational modelling of PR. The simulated results showed that severe PR leads to reduced cardiac outputs in both the LV and RV, clearly observable septum motion, and a significant increase in the average myofibre stress in the RV wall. These findings demonstrate the potential of the model for further exploration of PR.

Identification of rapid progression of right ventricular functional measures using three-dimensional cardiac computed tomography after total surgical correction of tetralogy of Fallot

OBJECTIVE

To identify subsets of patients with tetralogy of Fallot (TOF) after total surgical correction demonstrating the rapid progression of right ventricle (RV) functional measures using cardiac computed tomography (CT) ventricular volumetry.

METHODS

Rapid or slow progression of RV functional measures was determined in 109 patients with TOF who underwent cardiac CT ventricular volumetry more than twice after total surgical correction. Patient age, body surface area, postoperative days, the time interval between the first and last cardiac CT examinations, and CT-based functional measures were evaluated using binary logistic regression to determine the predictors of the rapid progression. Receiver operating characteristic curve analysis was performed to evaluate diagnostic performance of the potential predictors.

RESULTS

The rapid progression of indexed RV end-systolic volume (ESV) (≥2.7 mL/m²/year) and indexed RV end-diastolic volume (≥0.9 mL/m²/year) could be predicted by RV ejection fraction (EF) at the last cardiac CT with an odds ratio of 1.340 (95 % confidence interval [CI], 1.122-1.600; p = 0.001) and age at the last cardiac CT with an odds ratio of 8.255 (95 % CI, 1.531-44.513; p = 0.014), respectively. RV EF at the last cardiac CT showed the highest diagnostic performance (area under the curve = 0.799; p < 0.002) for the rapid progression of indexed RV ESV.

CONCLUSION

Cardiac CT ventricular volumetry can be used to identify patients demonstrating the rapid progression of RV functional measures after total surgical correction of TOF and follow-up imaging protocols can be individually optimized based on initial progression rate.

Echocardiographic predictors of severe right ventricular diastolic dysfunction in tetralogy of Fallot: Relations to patient outcomes

BACKGROUND

Previous studies have described echocardiographic indices of right ventricular (RV) diastolic function in patients with tetralogy of Fallot (TOF) but these indices have not been validated against invasive hemodynamic data. The purpose of this study was to determine echocardiographic predictors of severe RV diastolic dysfunction, and the impact of severe RV diastolic dysfunction on transplant-free survival.

METHODS

Cohort study of TOF patients that underwent non-simultaneous cardiac catheterization and echocardiogram at Mayo Clinic. Based on prior studies we selected these indices for assessment: tricuspid E/A, E/e', deceleration time, pulmonary artery forward flow, dilated inferior vena cava (IVC), and hepatic vein diastolic flow reversal (HVDFR). RV diastolic function classes (normal, mild/moderate and severe dysfunction) were created using arbitrary cut-off points of the median values of right ventricular end-diastolic pressure (RVEDP) and right atrial pressure (RAP) for the cohort.

RESULTS

Among 173 patients (age 40 ± 13 years), 68 patients were classified as normal (RVEDP≤14 and RAP≤10), 37 as mild/moderate dysfunction (either RVEDP>14 or RAP>10), and 69 as severe dysfunction (RVEDP>14 and RAP>10). Of the indices assessed, dilated IVC had the best sensitivity of 95% (area under the curve [AUC] 0.689) while HVDFR had the best specificity of 69% (AUC 0.648) for detecting severe RV diastolic dysfunction. Severe RV diastolic dysfunction was an independent risk factor for death/transplant (hazard ratio 2.83, p = 0.009).

CONCLUSION

Severe RV diastolic dysfunction, as defined by invasive hemodynamic indices, was associated with poor prognosis. Echocardiographic indices can identify these high risk patients, and hence improve risk stratification in clinical practice.

Impact of Inferior Venae Cava Assessment in Tetralogy of Fallot

Background

Inferior vena cava (IVC) size and collapsibility provide a noninvasive estimate of right heart filling pressures, an important determinant of right heart hemodynamic performance that is not measured by cardiac magnetic resonance imaging (CMRI). We hypothesized that compared with CMRI risk model alone, a combined CMRI-IVC risk model will have better correlation with disease severity and peak oxygen consumption in patients with tetralogy of Fallot (TOF).

Methods

We performed a retrospective review of patients with TOF with moderate/severe pulmonary regurgitation who underwent CMRI and echocardiography. A CMRI risk model was constructed using right ventricular (RV) end-diastolic volume index, RV end-systolic volume index, RV ejection fraction, and left ventricular ejection fraction. We added IVC hemodynamic classification to the CMRI indices to create CMRI-IVC risk model, and IVC hemodynamics were modeled as a categorical variable: normal vs mild/moderately abnormal (dilated IVC or reduced collapsibility) vs severely abnormal IVC hemodynamics (dilated IVC and reduced collapsibility). We defined disease severity as atrial arrhythmias, ventricular arrhythmias, and heart failure hospitalization.

Results

Of 207 patients, 131 (63%), 72 (35%), and 4 (2%) had normal, mild/moderately abnormal, and severely abnormal IVC hemodynamics, respectively. Compared with the CMRI risk model, the CMRI-IVC risk model had a better correlation with disease severity (area under the curve, 0.62; 95% confidence interval, 0.51-0.74 vs area under the curve 0.84, 95% confidence interval, 0.78-0.91, P = 0.006) and peak oxygen consumption (r = 0.35, P = 0.042 vs r = 0.43, P = 0.031, Meng test P = 0.026).

Conclusions

The combined CMRI-IVC risk model had a better correlation with disease severity compared with CMRI indices alone and can potentially improve risk stratification in the population with TOF.

Determinants and Prognostic Implications of Left-Heart Filling Pressures in Tetralogy of Fallot

BACKGROUND

Elevated pulmonary artery wedge pressure (PAWP) is the hallmark of left-heart failure and is responsible for heart failure symptoms and mortality. Although PAWP typically correlates with right atrial pressure (RAP), it is primarily dependent on left-heart myocardial properties and volume status. As right-heart disease can occur in the absence of left-heart disease in patients with tetralogy of Fallot (TOF), we hypothesized that RAP was the primary determinant of PAWP in this population.

METHODS

A cohort study of adults with TOF that underwent right-heart catheterization at Mayo Clinic Rochester (1990 to 2017) to determine the relationship among RAP, PAWP, and mortality.

RESULTS

Among 213 patients (male 105; age 37 ± 14 years), the mean PAWP was 14 ± 5 mm Hg, and RAP was 11 ± 5 mm Hg. RAP was the strongest predictor of PAWP (β = 0.68, standard error = 0.06, P < 0.001), independent of left-heart disease and atherosclerotic cardiovascular risk factors. The patients with high PAWP also had normal tissue Doppler velocities, suggesting normal left-ventricular myocardial properties. PAWP was an independent predictor of death/transplant (hazard ration [HR] 1.11, 95% confidence interval [CI], 1.03-1.20, P = 0.004). However, when RAP was incorporated into the regression model, RAP (and not PAWP) became the independent predictor of outcomes (HR 1.14, 95% CI, 1.06-1.22, P = 0.001).

CONCLUSIONS

The current study showed that RAP was the primary determinant of PAWP and accounts, to some extent, for the mortality in patients with TOF and high PAWP. The data provide new insight in the pathophysiology of disease progression for symptomatic patients with TOF.

Left ventricular filling pressure in Tetralogy of Fallot: Correlation between invasive and noninvasive indices

Background

Left heart filling pressures, as measured by pulmonary artery wedge pressure (PAWP), is associated with heart failure related mortality. Because of the prognostic importance of PAWP, several echocardiographic indices have been proposed for noninvasive assessment of PAWP. However, these indices have not been validated in the congenital heart disease population. The purpose of this study was to determine the correlation between echocardiographic indices of PAWP, and the effect of high PAWP on transplant-free survival in adults with tetralogy of Fallot (TOF).

Methods

Retrospective study of adult TOF patients that underwent cardiac catheterization at Mayo Clinic, 1990–2017. We selected these pre-defined set of echocardiographic indices of LV diastolic function: mitral valve early velocity (E), mitral valve early and late velocity ratio (E/A), mitral valve deceleration time (DT), mitral annular tissue Doppler early velocity (e′), and left atrial volume index (LAVI).

Results

Of the echocardiographic indices analyzed among 213 patients (age 37 ± 14 years), only E velocity (β = 5.83, standard error = 1.52, p < 0.001) and LAVI (β = 0.14, standard error = 0.05, p = 0.007) correlated with PAWP. LAVI > 28 ml/m² had sensitivity of 79% and specificity of 63% (AUC 0.712), and E velocity > 1.0 m/s had sensitivity of 66% and specificity of 89% (AUC 0.692), for detecting PAWP > 15 mmHg. LAVI > 28 ml/m² was associated with reduced 10-year transplant-free survival (49% vs 90%, p < 0.001).

Conclusion

This study supports the use of LAVI for noninvasive assessment of PAWP and for prognostication. Further studies are required to validate these results in a different population.

Prognostic Implications of Left Ventricular Cardiomyopathy in Adults With Tetralogy of Fallot

BACKGROUND

Despite the significant risk of cardiovascular mortality after tetralogy of Fallot (TOF) repair, there are limited data about left ventricular (LV) cardiomyopathy in this population, thus creating important knowledge gaps. This study aims to address some of these knowledge gaps by describing the risk and prognostic implications of LV systolic dysfunction (LVD) after TOF repair.

METHODS

We performed a cohort study of adult patients after TOF repair with an echocardiographic assessment of LV ejection fraction (LVEF) to determine the association between LVD and cardiovascular events, defined as sustained ventricular tachycardia, aborted sudden death, heart transplantation, or death. Prevalent and incidence LVD were defined as LVEF < 50% at baseline or new decrease in LVEF to < 50% during follow-up, respectively.

RESULTS

Of 574 patients (age 38 ± 13 years), the baseline LVEF was 57% ± 9% and 68 (12%) had prevalent LVD. Cardiovascular events occurred in 126 patients (22%) during 10.5 ± 6.2 years of follow-up. LVEF was an independent predictor of mortality (hazard ratio, 1.16; 95% confidence interval, 1.16-1.24; P = 0.003) per 5%-point decrease in LVEF. Among the 357 patients with preserved LVEF and echocardiographic follow-up, incident LVD occurred in 23 (6%) during 3.8 ± 1.6 years of follow-up. Event-free survival was significantly lower in patients with incident LVD compared with patients without incident LVD (87% vs 71%, P = 0.021).

CONCLUSION

Prevalent and incident LVD occurred in 12% and 6% of this cohort, respectively, and were associated with lower event-free survival. Incident LVD suggests the presence of subclinical LV cardiomyopathy, and further studies are required to determine optimal strategies for diagnosing and treating subclinical LV cardiomyopathy to improve outcomes in the population with TOF.

Pathophysiologic and Prognostic Implications of Right Atrial Hypertension in Adults With Tetralogy of Fallot

Background Right atrial pressure (RAP), a composite metric of right ventricular diastolic function, volume status, and right heart compliance, is a predictor of mortality in patients with heart failure due to acquired heart disease. Because patients with tetralogy of Fallot (TOF) might have abnormal right atrial and ventricular mechanics caused by myocardial injury and remodeling, we hypothesized that RAP would be associated with disease severity and cardiovascular adverse events in this population. Methods and Results We performed a cohort study of adults with TOF who underwent right heart catheterization at the Mayo Clinic Rochester between 1990 and 2017. The objective was to determine the association between RAP and multiple domains of disease severity in TOF (percentage of predicted peak oxygen consumption, atrial or ventricular arrhythmia, and heart failure hospitalization), as well as cardiovascular adverse events, defined as sustained ventricular tachycardia, resuscitated or aborted sudden death, heart transplantation, or death. Among 225 patients (113 male; mean age: 39±14 years), mean RAP was 10.7±5.2 mm Hg and median was 10 mm Hg (interquartile range: 7-13 mm Hg). Increasing RAP was associated with atrial or ventricular arrhythmias (odds ratio: 5.01; 95% CI, 1.22-23.49; P<0.001), heart failure hospitalization (odds ratio: 1.47; 95% CI, 1.10-2.39; P=0.033) per 5 mm Hg, and worsening exercise capacity (peak oxygen consumption; R2=0.74, r=-0.86, P<0.001). RAP was a predictor of cardiovascular adverse events (hazard ratio: 1.28; 95% CI, 1.10-1.47; P=0.028) per 5 mm Hg. Conclusions In symptomatic patients with TOF, increasing RAP correlates with multiple domains of disease severity (risk stratification) and predicts future cardiovascular events (prognostication). These data have potential clinical implications in the target population of symptomatic TOF patients.

The applications and potential limitations of right ventricular volumes as surrogate marker in tetralogy of fallot

Cardiac magnetic resonance imaging derived right ventricular (RV) volumes are often necessary for optimal timing of pulmonary valve replacement in patients with tetralogy of Fallot (TOF). This practice is based on previous studies that reported preoperative RV volumetric thresholds that predicted postoperative RV remodeling. As a result, pulmonary valve replacements are being performed even in asymptomatic patients based on RV volumetric thresholds that predict complete postoperative RVOT remodeling. Hence, RV volumes are now being used as surrogate markers/endpoints for future cardiovascular outcomes. Unfortunately, there are no studies showing survival benefit for performing pulmonary valve replacement at smaller RV volumes. This review underscores some of the limitations of using RV volumes as surrogate markers for clinical outcomes, and also highlights knowledge gaps about the pathophysiologic mechanism of cardiovascular death in the TOF population.

Usefulness of Right Ventricular Volumetric and Afterload Indices for Risk Stratification in Patients With Tetralogy of Fallot

Right ventricular (RV) volume overload due to chronic pulmonary regurgitation is the common mechanism for hemodynamic deterioration after tetralogy of Fallot (TOF) repair. As a result, RV volumetric indices are used for clinical risk stratification in this population. Since RV afterload is a determinant of RV hemodynamic performance, we hypothesized that afterload-adjusted RV volumetric indices will have a better correlation with disease severity compared with RV volumetric indices alone in patients with TOF. Cross-sectional study of adults with previous TOF repair that received care at Mayo Clinic, 2002-2015. We defined disease severity as atrial arrhythmia and/or impaired exercise capacity. We created afterload-adjusted RV volumetric indices by indexing these indices to RV systolic pressure (RVSP) as follows: RV end-diastolic volume (RVEDVi)/RVSP, RV end-systolic volume (RVESVi)/RVSP, and RV ejection fraction (RVEF)/RVSP. The RV volumetric indices were: RVEDVi 141 ± 43 ml/m², RVESVi 79 ± 38 ml/m², and RVEF 44 ± 10%, and RVSP was 48 ± 9 mm Hg. RVESVi was the only RV volumetric parameter that was associated with disease severity (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.01 to 1.32, p = 0.041) with area under the curve (AUC) of 0.612. In contrast RVEF/RVSP (OR 0.73, 95% CI 0.38 to 0.92, p = 0.037, AUC 0.649), and RVESVi/RVSP (OR 1.28, 95% CI 1.14-1.55, p = 0.008, AUC 0.798) were associated with disease severity. Compared with RV volumetric indices alone, the combined RV volumetric and afterload indices had better correlation with disease severity as measured by AUC. Afterload-adjusted RV volumetric indices had better correlation with disease severity, and may potentially improve risk stratification in this population.

Current outcomes and treatment of tetralogy of Fallot

Tetralogy of Fallot (ToF) is the most common type of cyanotic congenital heart disease. Since the first surgical repair in 1954, treatment has continuously improved. The treatment strategies currently used in the treatment of ToF result in excellent long-term survival (30 year survival ranges from 68.5% to 90.5%). However, residual problems such as right ventricular outflow tract obstruction, pulmonary regurgitation, and (ventricular) arrhythmia are common and often require re-interventions. Right ventricular dysfunction can be seen following longstanding pulmonary regurgitation and/or stenosis. Performing pulmonary valve replacement or relief of pulmonary stenosis before irreversible right ventricular dysfunction occurs is important, but determining the optimal timing of pulmonary valve replacement is challenging for several reasons. The biological mechanisms underlying dysfunction of the right ventricle as seen in longstanding pulmonary regurgitation are poorly understood. Different methods of assessing the right ventricle are used to predict impending dysfunction. The atrioventricular, ventriculo-arterial and interventricular interactions of the right ventricle play an important role in right ventricle performance, but are not fully elucidated. In this review we present a brief overview of the history of ToF, describe the treatment strategies currently used, and outline the long-term survival, residual lesions, and re-interventions following repair. We discuss important remaining challenges and present the current state of the art regarding these challenges.

Abnormal Pulmonary Arterial Elastance Is Associated With Reduced Exercise Capacity in Tetralogy of Fallot

Background

A previous study reported histologic abnormalities in the pulmonary artery (PA) of patients with tetralogy of Fallot (TOF). However, the potential effect of these anatomical findings on PA vascular function has not been studied. We hypothesized that TOF patients had abnormal PA vascular function, and that PA vascular function was associated with exercise capacity.

Methods and Results

This a study of adult TOF patients who had cardiac magnetic resonance imaging and echocardiogram (on the same day) at Mayo Clinic, 2002–2015. In order to test the study hypothesis, we compared PA elastance index (PAEi) between 207 TOF patients and a referent group of 8 subjects without structural heart disease. PAEi was calculated as a quotient of PA systolic pressure and cardiac magnetic resonance imaging–derived right ventricular stroke volume. Mean age was 33±13 and 36±4 years in the TOF and referent groups respectively. TOF patients had higher PAEi compared with the referent group (0.62±0.12 versus 0.48±0.08 mm Hg/mL/m²; P=0.001). There was a good correlation between PAEi and peak oxygen consumption (adjusted R²=0.73; r=0.85; P<0.001). After multivariate adjustment for potential confounders, PAEi was independently associated with peak oxygen consumption (adjusted R²=0.69; r=0.83; P<0.001).

Conclusions

The high PA elastance in the TOF group may be attributed to abnormal PA vascular function. The association between PAEi and exercise intolerance suggests that PA vascular dysfunction may contribute to exercise intolerance, which is an important clinical problem in this population. Further studies are required to validate our findings and explore potential therapies to improve PA vascular function in this population.