Reversible pulmonary trunk banding. II. An experimental model for rapid pulmonary ventricular hypertrophy

Right ventricular involvement in hypertrophic cardiomyopathy: evidence and implications from current literature

Objectives. In current guidelines, hypertrophic cardiomyopathy (HCM) is defined by hypertrophy of the left ventricle (LV). Less attention has been given to the right ventricle (RV) in patients with HCM. We wanted to provide an overview of current literature on RV involvement in HCM. Design. We performed a systematic search in PubMed and added additional articles by manual screening of references. The quality of the articles was assessed according to the GRADE system. Results. We identified 35 original articles on RV involvement in HCM. Based on these publications, RV hypertrophy occurs in 28-44% of HCM patients, depending on the cut-off value for hypertrophy and the method for assessment. Histological studies show the same structural changes in RV as are typically described in the LV cardiomyocyte hypertrophy and disarray, as well as fibrosis. These changes are similar, but less pronounced in the RV than in the LV. We discuss how HCM can impact the RV, either through a primary involvement similar to the LV or secondary to hemodynamic effects resulting from LV dysfunction. RV dysfunction in HCM is associated with higher mortality, partly due to an increased risk of ventricular tachycardia and sudden cardiac death. Conclusions. The evidence for RV involvement in HCM is limited. Multimodal imaging assessment of the RV should be included in the work-up of patients with HCM, and the added value of including RV function in the risk stratification algorithm should be further explored.

Better Outcomes in Pulmonary Arterial Hypertension After Repair of Congenital Heart Disease, Compared With Idiopathic Pulmonary Arterial Hypertension

Background

Pulmonary vascular changes in postoperative pulmonary artery hypertension (PAH) are similar to those seen in idiopathic PAH. Data are sparse on direct comparative midterm outcomes for these 2 high-risk populations.

Methods

Patients with idiopathic or postoperative PAH referred to a large tertiary hospital between June 2005 and July 2019 were retrospectively evaluated.

Results

A total of 364 consecutive patients were studied, including 201 postoperative PAH patients and 163 patients with idiopathic PAH, with a median age of 18.7 (interquartile range 10.0, 31.5) and 7.3 (IQR: 2.9, 18.3) years, respectively. PAH-specific drugs were used in 77.7% of patients; 31.4% received combination therapy. Patients with idiopathic PAH had a shorter 6-mintue walk distance, lower percutaneous oxygen saturation, and higher B-type natriuretic peptide levels than those with postoperative PAH at diagnosis (all P < 0.001), During a median follow-up time of 3.4 (interquartile range: 2.1, 5.8) years, 56 patients (15.4%) died, and one underwent bilateral lung transplantation. Patients with postoperative PAH had better survival than those with idiopathic PAH, according to age (hazard ratio [HR] 0.128, 95% confidence interval [CI]: 0.07-0.22, P < 0.0001); Kaplan–Meier survival estimates at 5 years for idiopathic and postoperative PAH patients were 74.3% and 92.6%, respectively. Patients in New York Heart Association functional class III–IV had an over 4-fold increased risk of death (HR 4.85, 95% CI: 2.61-9.00, P < 0.0001). Patients < 18 years of age at idiopathic PAH diagnosis had a worse survival compared to adult patients (HR 6.90, 95% CI: 4.19-15.56, P = 0.040).

Conclusions

Postoperative-PAH patients had better midterm survival compared to patients with idiopathic PAH. Mortality was significant in both PAH groups, reinforcing the need for early diagnosis and optimal individualized management to improve outcomes.

Reversible pulmonary trunk banding: Myocardial vascular endothelial growth factor expression in young goats submitted to ventricular retraining

Background

Ventricle retraining has been extensively studied by our laboratory. Previous studies have demonstrated that intermittent overload causes a more efficient ventricular hypertrophy. The adaptive mechanisms involved in the ventricle retraining are not completely established. This study assessed vascular endothelial growth factor (VEGF) expression in the ventricles of goats submitted to systolic overload.

Methods

Twenty-one young goats were divided into 3 groups (7 animals each): control, 96-hour continuous systolic overload, and intermittent systolic overload (four 12-hour periods of systolic overload paired with 12-hour resting period). During the 96-hour protocol, systolic overload was adjusted to achieve a right ventricular (RV) / aortic pressure ratio of 0.7. Hemodynamic evaluations were performed daily before and after systolic overload. Echocardiograms were obtained preoperatively and at protocol end to measure cardiac masses thickness. At study end, the animals were killed for morphologic evaluation and immunohistochemical assessment of VEGF expression.

Results

RV-trained groups developed hypertrophy of RV and septal masses, confirmed by increased weight and thickness, as expected. In the study groups, there was a small but significantly increased water content of the RV and septum compared with those in the control group (p<0.002). VEGF expression in the RV myocardium was greater in the intermittent group (2.89% ± 0.41%) than in the continuous (1.80% ± 0.19%) and control (1.43% ± 0.18%) groups (p<0.023).

Conclusions

Intermittent systolic overload promotes greater upregulation of VEGF expression in the subpulmonary ventricle, an adaptation that provides a mechanism for increased myocardial perfusion during the rapid myocardial hypertrophy of young goats.

The Association of Autoantibodies in Hyperthyroid Heart Disease Combined with Pulmonary Hypertension

Hyperthyroidism is a clinical state that results from increased thyroid hormone levels which has a significant impact on cardiac function and structure. Graves' disease is the most common cause of hyperthyroidism in iodine-replete areas. Hyperthyroid heart disease may be associated with pulmonary hypertension in patients who have overt hyperthyroidism. To investigate the association of pulmonary hypertension induced by hyperthyroid heart disease and autoantibody, one hundred and one cases with hyperthyroid heart disease who were consecutively admitted to the inpatient department of endocrinology and metabolism of the Shandong Provincial Hospital between November 2014 and April 2018 were collected and analyzed statistically. According to the Independent samples T-test, variance analysis, chi-square test, Pearson linear correlation analysis, and logistic regression, there was a good correlation between pulmonary artery systolic pressure and thyroid stimulating hormone (TSH) and receptor antibodies (TRAb) (r = 0.264, P=0.025) (OR = 1.037, P=0.029), but there was no significant correlation between the pulmonary artery systolic pressure and other thyroid-related parameters (FT3, FT4, TSH, anti-TPO, and anti-TG). Based on variance analysis, PASP rose as the level of TRAb gets higher. What is more, patients with HHD combined with PH showed a significantly higher serum level of TRAb; moreover, serum TRAb concentration was remarkably correlated with the PASP level. Therefore, TRAb participates in the process of pulmonary hypertension caused by hyperthyroid heart disease.

Assessment of Right Ventricular Function in the Research Setting: Knowledge Gaps and Pathways Forward. An Official American Thoracic Society Research Statement

BACKGROUND

Right ventricular (RV) adaptation to acute and chronic pulmonary hypertensive syndromes is a significant determinant of short- and long-term outcomes. Although remarkable progress has been made in the understanding of RV function and failure since the meeting of the NIH Working Group on Cellular and Molecular Mechanisms of Right Heart Failure in 2005, significant gaps remain at many levels in the understanding of cellular and molecular mechanisms of RV responses to pressure and volume overload, in the validation of diagnostic modalities, and in the development of evidence-based therapies.

METHODS

A multidisciplinary working group of 20 international experts from the American Thoracic Society Assemblies on Pulmonary Circulation and Critical Care, as well as external content experts, reviewed the literature, identified important knowledge gaps, and provided recommendations.

RESULTS

This document reviews the knowledge in the field of RV failure, identifies and prioritizes the most pertinent research gaps, and provides a prioritized pathway for addressing these preclinical and clinical questions. The group identified knowledge gaps and research opportunities in three major topic areas: 1) optimizing the methodology to assess RV function in acute and chronic conditions in preclinical models, human studies, and clinical trials; 2) analyzing advanced RV hemodynamic parameters at rest and in response to exercise; and 3) deciphering the underlying molecular and pathogenic mechanisms of RV function and failure in diverse pulmonary hypertension syndromes.

CONCLUSIONS

This statement provides a roadmap to further advance the state of knowledge, with the ultimate goal of developing RV-targeted therapies for patients with RV failure of any etiology.

Alterations in cardiovascular function in an experimental model of lung fibrosis and pulmonary hypertension

NEW FINDINGS

What is the central question of this study? We have evaluated changes in cardiovascular physiology using echocardiography in an experimental model of lung fibrosis. What is the main finding and its importance? Remarkably, we report changes in cardiovascular function as early as day 7, concomitant with evidence of vascular remodelling. We also report that isolated pulmonary arteries were hypercontractile in response to a thromboxane A2 agonist. These findings are significant because the development of pulmonary hypertension is one of the most significant predictors of mortality in patients with lung fibrosis, where there are no available therapies and a lack of animal models.

ABSTRACT

Group III pulmonary hypertension is observed in patients with chronic lung diseases such as chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis. Pulmonary hypertension (PH) develops as a result of extensive pulmonary vascular remodelling and resultant changes in vascular tone that can lead to right ventricle hypertrophy. This eventually leads to right heart failure, which is the leading indicator of mortality in patients with idiopathic pulmonary fibrosis. Treatments for group III PH are not available, in part owing to a lack of viable animal models. Here, we have evaluated the cardiovascular changes in a model of lung fibrosis and PH. Data obtained from this study indicated that structural alterations in the right heart, such as right ventricular wall hypertrophy, occurred as early as day 14, and similar increases in right ventricle chamber size were seen between days 21 and 28. These structural changes were correlated with decreases in the systolic function of the right ventricle and right ventricular cardiac output, which also occurred between the same time points. Characterization of pulmonary artery dynamics also highlighted that PH might be occurring as early as day 21, indicated by reductions in the velocity-time integral; however, evidence for PH is apparent as early as day 7, indicated by the significant reduction in pulmonary acceleration time values. These changes are consistent with evidence of vascular remodelling observed histologically starting on day 7. In addition, we report hyperactivity of bleomycin-exposed pulmonary arteries to a thromboxane A2 receptor (Tbxa2r) agonist.

Treatment strategies for the right heart in pulmonary hypertension

The function of the right ventricle (RV) determines the prognosis of patients with pulmonary hypertension. While much progress has been made in the treatment of pulmonary hypertension, therapies for the RV are less well established. In this review of treatment strategies for the RV, first we focus on ways to reduce wall stress since this is the main determinant of changes to the ventricle. Secondly, we discuss treatment strategies targeting the detrimental consequences of increased RV wall stress. To reduce wall stress, afterload reduction is the essential. Additionally, preload to the ventricle can be reduced by diuretics, by atrial septostomy, and potentially by mechanical ventricular support. Secondary to ventricular wall stress, left-to-right asynchrony, altered myocardial energy metabolism, and neurohumoral activation will occur. These may be targeted by optimising RV contraction with pacing, by iron supplement, by angiogenesis and improving mitochondrial function, and by neurohumoral modulation, respectively. We conclude that several treatment strategies for the right heart are available; however, evidence is still limited and further research is needed before clinical application can be recommended.

Emerging role of angiogenesis in adaptive and maladaptive right ventricular remodeling in pulmonary hypertension

Right ventricular (RV) function is the primary prognostic factor for both morbidity and mortality in pulmonary hypertension (PH). RV hypertrophy is initially an adaptive physiological response to increased overload; however, with persistent and/or progressive afterload increase, this response frequently transitions to more pathological maladaptive remodeling. The mechanisms and disease processes underlying this transition are mostly unknown. Angiogenesis has recently emerged as a major modifier of RV adaptation in the setting of pressure overload. A novel paradigm has emerged that suggests that angiogenesis and angiogenic signaling are required for RV adaptation to afterload increases and that impaired and/or insufficient angiogenesis is a major driver of RV decompensation. Here, we summarize our current understanding of the concepts of maladaptive and adaptive RV remodeling, discuss the current literature on angiogenesis in the adapted and failing RV, and identify potential therapeutic approaches targeting angiogenesis in RV failure.

Pulmonary Hypertension Associated with Idiopathic Pulmonary Fibrosis: Current and Future Perspectives

Pulmonary hypertension (PH) is commonly present in patients with chronic lung diseases such as Chronic Obstructive Pulmonary Disease (COPD) or Idiopathic Pulmonary Fibrosis (IPF) where it is classified as Group III PH by the World Health Organization (WHO). PH has been identified to be present in as much as 40% of patients with COPD or IPF and it is considered as one of the principal predictors of mortality in patients with COPD or IPF. However, despite the prevalence and fatal consequences of PH in the setting of chronic lung diseases, there are limited therapies available for patients with Group III PH, with lung transplantation remaining as the most viable option. This highlights our need to enhance our understanding of the molecular mechanisms that lead to the development of Group III PH. In this review we have chosen to focus on the current understating of PH in IPF, we will revisit the main mediators that have been shown to play a role in the development of the disease. We will also discuss the experimental models available to study PH associated with lung fibrosis and address the role of the right ventricle in IPF. Finally we will summarize the current available treatment options for Group III PH outside of lung transplantation.

The Impact of Sevoflurane on Coupling of the Left Ventricular-to-Systemic Vasculature in Rats With Chronic Pulmonary Hypertension

OBJECTIVES

The relationship between left ventricular function and afterload has not been investigated as much as the right ventricular function under chronic pulmonary hypertension (PH) during anesthesia. This study was designed to investigate effects of sevoflurane on the intrinsic coupling relationship between the left ventricle and systemic vasculature in the presence of PH.

DESIGN

A randomized, controlled study.

SETTING

University hospital.

PARTICIPANTS

Sprague-Dawley rats.

INTERVENTIONS

Monocrotaline (MCT) was injected intraperitoneally to induce a PH model.

MEASUREMENTS AND MAIN RESULTS

Four weeks later, rats with MCT injection demonstrated significantly increased pulmonary arterial pressure and right/left ventricular systolic ratio of ventricular pressure (p < 0.001). Rats were treated with 1.5% sevoflurane inhalation. The PV catheters were inserted and left ventricular pressure-volume loops were measured at baseline, 30, 60, and 90 minutes during sevoflurane treatment. Preload recruitable stroke work and end-systolic elastance were decreased markedly in rats with MCT injection (p < 0.05). However, arterial elastance decreased similarly in both groups. Sarcoplasmic reticulum Ca²⁺-ATPase (SERCA2a) level was decreased and the expression of phospholamban (PLB) was increased in the PH group and after sevoflurane treatment. PH rats suffered further SERCA2/PLB ratio decrease from their already low baseline. The left ventricular contractility and ventricular-vascular coupling were decreased in rats with PH after sevoflurane inhalation.

CONCLUSIONS

Sevoflurane reduced SERCA2a expression and increased PLB expression in PH rats. This partially could explain why the LV contractility and ventricular-to-vasculature coupling of PH rats were attenuated after sevoflurane treatment.

Management of pulmonary hypertension and right heart failure in the intensive care unit

Management of acute right ventricular failure, both with and without coexisting pulmonary hypertension, is a common challenge encountered in the intensive care setting. Both right ventricular dysfunction and pulmonary hypertension portend a poor prognosis, regardless of the underlying cause and are associated with significant morbidity and mortality. The right ventricle is embryologically distinct from the left ventricle and has unique morphologic and functional properties. Management of right ventricular failure and pulmonary hypertension in the intensive care setting requires tailored hemodynamic management, pharmacotherapy, and often mechanical circulatory support. Unfortunately, our understanding of the management of right ventricular failure lags behind that of the left ventricle. In this review, we will explore the underlying pathophysiology of the failing right ventricle and pulmonary vasculature in patients with and without pulmonary hypertension and discuss management strategies based on evidence-based studies as well as our current understanding of the underlying physiology.

The role of pulmonary arterial stiffness in COPD

COPD is the second most common cause of pulmonary hypertension, and is a common complication of severe COPD with significant implications for both quality of life and mortality. However, the use of a rigid diagnostic threshold of a mean pulmonary arterial pressure (mPAP) of ≥25mHg when considering the impact of the pulmonary vasculature on symptoms and disease is misleading. Even minimal exertion causes oxygen desaturation and elevations in mPAP, with right ventricular hypertrophy and dilatation present in patients with mild to moderate COPD with pressures below the threshold for diagnosis of pulmonary hypertension. This has significant implications, with right ventricular dysfunction associated with poorer exercise capability and increased mortality independent of pulmonary function tests.

The compliance of the pulmonary artery (PA) is a key component in decoupling the right ventricle from the pulmonary bed, allowing the right ventricle to work at maximum efficiency and protecting the microcirculation from large pressure gradients. PA stiffness increases with the severity of COPD, and correlates well with the presence of exercise induced pulmonary hypertension. A curvilinear relationship exists between PA distensibility and mPAP and pulmonary vascular resistance (PVR) with marked loss of distensibility before a rapid rise in mPAP and PVR occurs with resultant right ventricular failure. This combination of features suggests PA stiffness as a promising biomarker for early detection of pulmonary vascular disease, and to play a role in right ventricular failure in COPD. Early detection would open this up as a potential therapeutic target before end stage arterial remodelling occurs.

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Pulmonary hypertension is common in COPD.

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Right ventricular remodeling occurs at pressures below the diagnostic threshold of PH.

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Pulmonary arterial stiffening occurs early in the development of PH.

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Non-invasive measurement of pulmonary stiffness may serve as an early biomarker of PH.

Relationship between severity of pulmonary hypertension and coronary sinus diameter

INTRODUCTION AND OBJECTIVE

We investigated the relationship between coronary sinus (CS) diameter and pulmonary artery systolic pressure (PASP) in patients with pulmonary hypertension (PH) and normal left ventricular systolic function.

METHODS

A total of 155 participants referred for transthoracic echocardiography were included in the study. The study population consisted of 100 patients with chronic PH and 55 control subjects. Patients with PH were divided into two groups according to PASP: those with PASP 36-45 mmHg, the mild PH group (n=53); and those with PASP >45 mmHg, the moderate to severe PH group (n=47). CS diameter was measured from the posterior atrioventricular groove in apical 4-chamber view during ventricular systole according to the formula: mean CS=(proximal CS+mid CS+distal CS)/3.

RESULTS

Mean CS diameter was significantly higher in the moderate to severe PH group than in the controls and in the mild PH group (1.12±0.2 cm vs. 0.82±0.1 cm and 0.87±0.1 cm, respectively; p<0.001). It was significantly correlated with right atrial (RA) area (r=0.674, p<0.001), RA pressure (r=0.458, p<0.001), PASP (r=0.562, p<0.001), inferior vena cava diameter (r=0.416, p<0.001), right ventricular E/A ratio (r=-0.290, p<0.001), and E/Em ratio (r=0.235, p=0.004). RA area (β=0.475, p<0.001) and PASP (β=0.360, p=0.002) were found to be independent predictors of CS diameter.

CONCLUSIONS

A dilated CS was associated with moderate to severe pulmonary hypertension, and RA area and PASP were independent predictors of CS diameter.

Pulmonary hypertension and congenital heart disease: An insight from the REHAP National Registry

BACKGROUND

Pulmonary arterial hypertension (PAH) is common in patients with congenital heart disease (CHD). Although Eisenmenger syndrome may be on decline, other types of PAH-CHD are increasing and little is known on long-term outcome of this population. We report the PAH-CHD population of Spain via a national registry with focus on long-term survival.

METHODS AND RESULTS

A total of 240 consecutive patients (age 37.7 ± 14.1 years, 67.9% females) with PAH-CHD included in the REHAP registry were analysed. Patients were classified into 3 groups: 1) Eisenmenger syndrome, 2) postoperative-PAH and 3) PAH associated with small defects. Over a median follow-up time of 4.5[1.6-7.1]years, 50 patients (20.8%) died or underwent lung/heart-lung transplantation. Patients with Eisenmenger syndrome had better survival than postoperative-PAH (HR 0.1 95% CI: 0.2-0.9, p=0.048) but no advantage compared to small defects (HR 4.4, 95% CI 0.6-31.4, p=0.15). In the overall PAH-CHD population, patients in NYHA functional class III-IV had a 3-fold increased risk of death (HR 3.0, 95% CI: 1.5-5.9, p=0.001). Amongst patients with Eisenmenger syndrome, a pre-tricuspid shunt had a 2.6-fold increase risk of death (HR 2.6, 95% CI: 1.2-5.6, p=0.03). There was no significant difference in survival between patients with postoperative-PAH and patients with iPAH (HR 0.99 95% CI: 0.6-1.7, p=0.97).

CONCLUSION

PAH-CHD is associated with mid to long-term mortality. Outcome relates closely to functional class, type of PAH-CHD and within the Eisenmenger cohort, with location of the shunt. Adults with postoperative-PAH have the worse prognosis in the PAH-CHD cohort, reinforcing the need for lifelong close follow-up of such patients.

The echocardiography in the cardiovascular laboratory: a guide to research with animals

The feasibility and potential for the morphological and hemodynamic investigation of the heart has been increasing the use of the echocardiography in the research setting. Additionally, the development of new technologies, like the real time 3D echocardiography and speckle tracking, demands validation throughout experimental studies before being instituted in the clinical setting.

This paper aims to provide information concerning the particularities of the echocardiographic examination in quadruped mammals, targeting the experimental research.

A comprehensive review: the evolution of animal models in pulmonary hypertension research; are we there yet?

Pulmonary hypertension (PH) is a disorder that develops as a result of remodeling of the pulmonary vasculature and is characterized by narrowing/obliteration of small pulmonary arteries, leading to increased mean pulmonary artery pressure and pulmonary vascular resistance. Subsequently, PH increases the right ventricular afterload, which leads to right ventricular hypertrophy and eventually right ventricular failure. The pathophysiology of PH is not fully elucidated, and current treatments have only a modest impact on patient survival and quality of life. Thus, there is an urgent need for improved treatments or a cure. The use of animal models has contributed extensively to the current understanding of PH pathophysiology and the investigation of experimental treatments. However, PH in current animal models may not fully represent current clinical observations. For example, PH in animal models appears to be curable with many therapeutic interventions, and the severity of PH in animal models is also believed to correlate poorly with that observed in humans. In this review, we discuss a variety of animal models in PH research, some of their contributions to the field, their shortcomings, and how these have been addressed. We highlight the fact that the constant development and evolution of animal models will help us to more closely model the severity and heterogeneity of PH observed in humans.

Right ventricular myocardial performance index is decreased with severe pressure-overload cardiac hypertrophy in young rats

Although the right ventricular (RV) myocardial performance index (MPI) usually is increased in the presence of RV dysfunction and pressure overload, debate continues over the correlation between the RV MPI and functional derangement in patients with RV pressure-overload congenital heart disease (CHD). To address this controversy, this study took serial measurements of the RV MPI in addition to invasive RV hemodynamic measurements during the acute stage of mild to severe pressure overload. Right ventricle pressure overload was induced by partial pulmonary arterial banding (PAB) in 3-week-old rats. The rats were divided into two groups: mild pulmonary stenosis (PS) group (20-40 % stenosis; n = 20) and severe PS group (40-70 % stenosis; n = 28). Sham-treated animals (sham group; n = 30) underwent the same surgical procedure without PAB. Pressure-overload RV hypertrophy was documented by weighing the heart, by evaluating echocardiograms, and by evaluating cardiac hypertrophy-associated gene expression. The RV MPI was checked 1, 2, 3, 5, and 8 weeks after PAB. The MPI was calculated as the sum of the isovolumic contraction time and the isovolumic relaxation time (IRT) divided by the ejection time. The RV MPI of the mild PS group did not differ significantly from that of the sham group. The RV MPI of the severe PS group, however, was lower than that of the sham group (0.27 ± 0.01 vs 0.29 ± 0.01) 2 to 8 weeks after PAB: 0.19 ± 0.01 at 2 weeks (P < 0.001), 0.16 ± 0.01 at 3 weeks (P < 0.001), 0.20 ± 0.01 at 5 weeks (P = 0.021), and 0.18 ± 0.01 at 8 weeks (P < 0.001) after PAB. The decreased RV MPI was associated with decreased IRT and increased ejection time. RV hypertrophy contributes to the decrease in the RV MPI in the severe pressure-overload condition.

The right ventricle: biologic insights and response to disease: updated

Despite ample evidence that right ventricular function is a critical determinant of the clinical response to a spectrum of cardiovascular diseases, there has been only a limited analysis of the unique and distinguishing physiologic properties of the RV under normal circumstances and in response to pathologic insults. This knowledge deficit is increasingly acknowledged. This review highlights some of these features and underscores the fact that rational therapy in RV failure needs to acknowledge its unique physiology and ought to be chamber specific. That is proven therapies for LV dysfunction do not necessarily apply to the RV. The updated version of this review now acknowledges recent advances in the understanding of metabolic, inflammatory and gender-specific influences on the right ventricle.

Cardiac natriuretic Peptide gene expression and plasma concentrations during the first 72 hours of life in piglets

Plasma measurement of cardiac natriuretic peptides constitutes promising markers of congenital heart disease. However, concentrations change rapidly and dramatically during the first days after delivery even in healthy neonates, which complicates clinical interpretation. It is unknown whether these changes in plasma concentrations are explained by corresponding changes in the cardiac gene expression. We quantified the chamber-specific mRNA levels of ANP (A-type natriuretic peptide) and BNP (B-type natriuretic peptide) and plasma pro-ANP and BNP-32 concentrations in healthy piglets during the first 72 hours of life (from 2 litters, n = 44). Chamber-specific ANP and BNP mRNA levels reflected hemodynamic neonate changes at birth but did not correlate with circulating natriuretic peptide concentrations. However, plasma pro-ANP and creatinine concentrations were closely correlated (P < .0001; r = 0.73). Plasma pro-ANP levels were highest on the day of delivery (5580 pmol/L [4320-6786] decreasing to 2484 pmol/L [1602-2898] after 72 hours, P < .0001). During the 72 hours, gel chromatography suggested that the translational products in circulation and in atrial tissue were immature, ie, unprocessed pro-ANP. In contrast to pro-ANP, BNP-32 plasma concentrations were low at delivery and peaked after 48 hours (12 [10.5-20.6] vs. 88.8 [71.7-101.4] pmol/L, P < .0001). To conclude, ANP and BNP gene expression differs considerably between cardiac chambers in the first 72 hours of life in healthy piglets, resembling the transition from fetal to neonate circulation. However, the cardiac gene expression does not explain plasma concentrations.

Metabolism of the right ventricle and the response to hypertrophy and failure

Profound transcriptional, translational and energetic derangements develop in the right ventricle (RV) in response to physiologic and pathophysiologic stress. The transition from pressure and volume overload to cardiac hypertrophy and subsequent failure is accompanied by a distinct switch from preferential fatty acid to glucose utilization for ATP generation. The failing RV is characterized by an energy-starved state with insufficient ATP levels. Modern non-invasive imaging using positron emission tomography using specific radioactive tracers allows a detailed spatial and temporal characterization of RV metabolism. While the current role for pharmacologic interventions on RV metabolic abnormalities is unclear, several potentially promising molecular targets have been identified and clinical trials targeting molecular dysfunction in RV hypertrophy and failure have been designed.

Right ventricular remodeling in pulmonary hypertension

The right ventricle (RV) is in charge of pumping blood to the lungs for oxygenation. Pulmonary arterial hypertension (PAH) is characterized by high pulmonary vascular resistance and vascular remodeling, which results in a striking increase in RV afterload and subsequent failure. There is still unexploited potential for therapies that directly target the RV with the aim of supporting and protecting the right side of the heart, striving to prolong survival in patients with PAH.

Characterizing the right ventricle: advancing our knowledge

Our ability to evaluate the right ventricle (RV) in pulmonary hypertension has traditionally been quite limited: the RV's complex anatomy is not adequately represented by 2-dimensional imaging, and our understanding of what is an adaptive and maladaptive RV response is incomplete. However, measures of RV function appear to be a strong predictor of survival in pulmonary hypertension. This is, therefore, a promising area for future study. To more fully understand the challenges and opportunities in this area, this article provides a review of RV embryology and anatomy, current assessment of the RV function, animal models of RV function, RV-pulmonary artery coupling, and how translating lessons from studies of the left ventricle may increase our knowledge of the RV.

Reversible pulmonary trunk banding: VII. Stress echocardiographic assessment of rapid ventricular hypertrophy in young goats

BACKGROUND

Ventricle retraining with abrupt systolic overload can cause myocardial edema and necrosis, followed by late ventricular failure. Intermittent systolic overload could minimize the inadequacy of conventional pulmonary artery banding. The present study compared ventricle function under dobutamine stress in 2 protocols of systolic overload in young goats.

METHODS

Nineteen young goats were divided into 3 groups: sham (n = 7; no systolic pressure overload), continuous (n = 6; systolic overload maintained for 96 hours), and intermittent (n = 6; 4 periods of 12-hour systolic overload, paired with a 12-hour resting period). Echocardiographic and hemodynamic evaluations were performed daily. The myocardial performance index and ejection fraction were evaluated at rest and during dobutamine stress. The goats were then killed for morphologic evaluation.

RESULTS

The intermittent group underwent less systolic overload than the continuous group (P < .05). Nevertheless, both groups had increased right ventricular and septal masses compared with the sham group (P < .0002). Echocardiography revealed a major increase in right ventricular wall thickness in the intermittent group (+64.8% ± 23.37%) compared with the continuous group (+43.9% ± 19.26%; P = .015). Only the continuous group remained with significant right ventricular dilation throughout the protocol (P < .001). The intermittent group had a significantly better myocardial performance index at the end of the protocol, under resting and dobutamine infusion, compared with the continuous group (P < .012).

CONCLUSIONS

Both systolic overload protocols have induced rapid right ventricular hypertrophy. However, only the intermittent group had better preservation of right ventricular function at the end of the protocol, both at rest and during dobutamine infusion.

Intensive care unit management of patients with severe pulmonary hypertension and right heart failure

Despite advances in medical therapies, pulmonary arterial hypertension (PAH) continues to cause significant morbidity and mortality. Although the right ventricle (RV) can adapt to an increase in afterload, progression of the pulmonary vasculopathy that characterizes PAH causes many patients to develop progressive right ventricular failure. Furthermore, acute right ventricular decompensation may develop from disorders that lead to either an acute increase in cardiac demand, such as sepsis, or to an increase in ventricular afterload, including interruptions in medical therapy, arrhythmia, or pulmonary embolism. The poor reserve of the right ventricle, RV ischemia, and adverse right ventricular influence on left ventricular filling may lead to a global reduction in oxygen delivery and multiorgan failure. There is a paucity of data to guide clinicians caring for acute right heart failure in PAH. Treatment recommendations are frequently based on animal models of acute right heart failure or case series in humans with other causes of pulmonary hypertension. Successful treatment often requires that invasive hemodynamics be used to monitor the effect of strategies that are based primarily on biological plausibility. Herein we have developed an approach based on the current understanding of RV failure in PAH and have attempted to develop a treatment paradigm based on physiological principles and available evidence.

Significance of electrocardiographic right ventricular hypertrophy in patients with pulmonary hypertension with or without right ventricular systolic dysfunction

OBJECTIVE

We sought to determine the value of electrocardiographic right ventricular hypertrophy (ECG-RVH) in pulmonary hypertension (PH) patients with right ventricular systolic dysfunction defined by cardiac magnetic resonance (CMR-RVSD).

PATIENTS

A total of 31 consecutive patients with PH with a mean pulmonary arterial pressure of >25 mmHg underwent both ECG and CMR studies. Patients were divided into 2 groups according to the presence of RVSD, defined as a RV ejection fraction <35%. Logistic regression modeling was performed to define the association between ECG-RVH and CMR-RVSD.

RESULTS

About half of the patients had RVSD (n=15 ; 48%). The R to S wave ratio (p=0.01) or incidence of qR pattern (p=0.002) in lead V(1) was significantly greater in patients with PH complicated by RVSD than in those without RVSD. These 2 patterns were significant predictors of RVSD [odds ratio (OR), 19.3 for qR; OR, 14.0 for R/S>1] and when each of these ECG findings was assigned with a point proportional to OR (score of 2 for qR in lead V(1) and score of 1 for R/S>1 in lead V(1)), the incidence of RVSD increased by the total ECG score.

CONCLUSION

The combination of ECG-RVH findings, especially in lead V(1), predicts the presence of RVSD defined by CMR. ECG might be a useful tool for estimating the presence of RVSD in patients with PH.

Perioperative management of pulmonary hypertension in children with critical heart disease

OPINION STATEMENT

Pulmonary hypertension (PHTN) is common to a variety of conditions occurring in infants and children presenting to the intensive care unit. A fundamental understanding of the response of the right ventricle to an increase in afterload and the clinical syndromes responsible for PHTN is essential for managing patients with PHTN and critical heart disease. There are important distinguishing features between PHTN syndromes, and although one form of PHTN may predominate, often more than one mechanism of PHTN is contributing to the pathophysiologic state. Thus, it is imperative to tailor therapies accordingly in order to optimize outcomes.

Reversible pulmonary trunk banding. VI: Glucose-6-phosphate dehydrogenase activity in rapid ventricular hypertrophy in young goats

OBJECTIVE

Increased myocardial glucose-6-phosphate dehydrogenase (G6PD) activity occurs in heart failure. This study compared G6PD activity in 2 protocols of right ventricle (RV) systolic overload in young goats.

METHODS

Twenty-seven goats were separated into 3 groups: sham (no overload), continuous (continuous systolic overload), and intermittent (four 12-hour periods of systolic overload paired with a 12-hour resting period). During a 96-hour protocol, systolic overload was adjusted to achieve a 0.7 RV/aortic pressure ratio. Echocardiographic and hemodynamic evaluations were performed before and after systolic overload every day postoperatively. After the study period, the animals were humanely killed for morphologic and G6PD tissue activity assessment.

RESULTS

A 92.1% and 46.5% increase occurred in RV and septal mass, respectively, in the intermittent group compared with the sham group; continuous systolic overload resulted in a 37.2% increase in septal mass. A worsening RV myocardial performance index occurred in the continuous group at 72 hours and 96 hours, compared with the sham (P < .039) and intermittent groups at the end of the protocol (P < .001). Compared with the sham group, RV G6PD activity was elevated 130.1% in the continuous group (P = .012) and 39.8% in the intermittent group (P = .764).

CONCLUSIONS

Continuous systolic overload for ventricle retraining causes RV dysfunction and upregulation of myocardial G6PD activity, which can elevate levels of free radicals by NADPH oxidase, an important mechanism in the pathophysiology of heart failure. Intermittent systolic overload promotes a more efficient RV hypertrophy, with better preservation of myocardial performance and and less exposure to hypertrophic triggers.

The right ventricle: biologic insights and response to disease

Despite ample evidence that right ventricular function is a critical determinant of the clinical response to a spectrum of cardiovascular diseases, there has been only a limited analysis of the unique and distinguishing physiologic properties of the RV under normal circumstances and in response to pathologic insults. This review highlights some of these features and underscores the fact that rational therapy in RV failure should acknowledge this physiology and ought to be chamber specific.

Pulmonary Artery Banding

Proponents of a telemetrically adjustable pulmonary artery band (PAB) device have cited simplified postoperative management and shortened length of stay as advantages associated with that technology. This report concerns a recent experience with both conventional pulmonary artery banding (conv-PAB) and the telemetrically adjustable PAB FloWatch (FW-PAB). From January 2005 through December 2008, 19 consecutive infants underwent either conv-PAB (8 patients, mean age 3.5 months, mean weight 4.1 kg) or FW-PAB (11 patients, mean age 2.6 months, mean weight 3.1 kg). Indications for PAB were left ventricular retraining (1 patient in FW-PAB), palliation prior to biventricular repair (7 patients in conv-PAB and 10 in FW-PAB group), and staged univentricular repair (1 patient in conv-PAB). In-hospital mortality was 0%. In the FW-PAB group, 1 FloWatch device was removed because of hemodynamic compromise related to the bulk of the device. There were no major complications in the conv-PAB group and no differences between groups with respect to postoperative ventilation time or length of stay in the intensive care unit or in hospital. In the FW-PAB group, a mean of 3.1 ± 1.7 regulations per patient were undertaken. Of the regulations, 85% (29/34) were adjustments to tighten the device, and 15% (5/34) were to loosen it. During follow-up, 8 patients underwent intracardiac repair and pulmonary artery debanding: 4 in the conv-PAB group and 4 in the FW-PAB group. The course of patients in both groups after PAB were similar. Major differences in length of stay and resource utilization were not apparent.

Pathophysiology of right ventricular failure in pulmonary hypertension

This review focuses on right ventricular anatomy and function and the significance of ventricular interdependence in the response of the right ventricle to an increase in afterload. This is followed by a discussion of the pathophysiology of right ventricular failure in pulmonary arterial hypertension as well as in other clinical syndromes of pulmonary hypertension. Pulmonary hypertension is common in critically ill children and is associated with several conditions. Regardless of the etiology, an increase in right ventricular afterload leads to a number of compensatory changes in cardiovascular physiology. These changes are not altogether intuitive and require an understanding of right ventricular physiology and ventricular interdependence to optimize the care of these patients.

Right heart function and haemodynamics in pulmonary hypertension

The primary challenge in the care of the patient with advanced pulmonary arterial hypertension (PAH) is right ventricular dysfunction with concomitant right heart failure. Right heart function is closely tied to survival in this disease, and there is a growing interest in the study of this unique structure. While echocardiography and cardiac magnetic resonance (CMR) have augmented our ability to image the right ventricle (RV), the primary means of assessing right heart function remains right heart catheterisation. Several of the currently available treatments for PAH have been shown to have effects on the RV, not just the pulmonary vasculature, and, in future, therapies aimed at optimizing right ventricular function may allow better outcomes in this challenging disease. New directions in right ventricular assessment including measurement of pulmonary vascular impedance and more widespread availability of CMR may allow greater knowledge about this little studied, yet highly important, right side of the heart.

Pulmonary hypertension associated with COPD

Although the prevalence of pulmonary hypertension (PH) in individuals with chronic obstructive pulmonary disease (COPD) is not known precisely, approximately 10%–30% of patients with moderate to severe COPD have elevated pulmonary pressures. The vast majority of PH associated with COPD is mild to moderate and severe PH occurs in <5% of patients. When COPD is associated with PH, both mortality and morbidity are increased. There are no clinical or physical examination findings that accurately identify patients with underlying PH. Radiographic imaging findings are specific but not sensitive indicators of PH. Echocardiography is the principle noninvasive diagnostic test but may be technically limited in a significant proportion of patients with COPD. Right heart catheterization is required for accurate measurement of pulmonary pressures. The combined effects of inflammation, endothelial cell dysfunction, and angiogenesis appear to contribute to the development of PH associated with COPD. Systemic vasodilators have not been found to be effective therapy. Selective pulmonary vasodilators including inhaled nitric oxide and phosphodiesterase inhibitors are promising treatments for patients with COPD associated PH but further evaluation of these medications is needed prior to their routine use.

Hybrid management for hypoplastic left heart syndrome : an experience from Brazil

Initial surgical reconstruction for hypoplastic left heart syndrome (HLHS) is associated with satisfactory outcomes only in a few referral centers. Moreover, there is a persistent high-risk period for sudden death while the patient waits for the next surgical procedure. The development of a less invasive approach, so-called "hybrid," postponing a major surgery outside the neonatal period, might reduce the immediate and late surgical burden on these patients. This is a retrospective study of a contemporary series of patients with HLHS seen in two separate institutions. Patients with HLHS or its variants who underwent a "hybrid" management were included in the study. Data are described as the mean and standard deviation or absolute numbers and percentage, as appropriate. From January 2004 to June 2006, 15 patients (10 male; 5 +/- 3.8 days old and 2.9 +/- 0.5 kg) were included in the study. Ten had both mitral and aortic atresia; the ascending aorta and atrial septal defect measured 2.5 +/- 1.4 and 4.9 +/- 1.2 mm, respectively. There were six hospital survivors after stage I (mortality rate 60%). During the interstage period, all but one patient needed additional procedures. One patient died of bacterial meningitis 4 months after stage I. Four patients were submitted to stage II operation at 6.6 +/- 0.5 months of age and one is waiting for the operation. All four required early reinterventions for pulmonary artery stenosis. Only one was discharged home and was not yet submitted to the third stage. The hybrid approach for HLHS was associated with poor results in this early experience from two independent institutions in a developing country. This might have been related to infrastructure and technical problems, as well as our own learning curve. Institutions working under the same conditions might face similar problems during their initial experience.