Right ventricular failure complicating heart failure: pathophysiology, significance, and management strategies

The Effects of Radiofrequency Catheter Ablation for Atrial Fibrillation on Right Ventricular Function

BACKGROUND AND OBJECTIVE

The effects of radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) on right ventricular (RV) function are not well known.

METHODS

Patients who underwent RFCA for AF and underwent pre- and post-procedural echocardiography were enrolled consecutively. Fractional area change (FAC), RV free-wall longitudinal strain (RVFWSL), and RV 4-chamber strain including the ventricular septum (RV4CSL) were measured. Changes in FAC, RVFWSL, and RV4CSL before and after RFCA were compared among paroxysmal AF (PAF), persistent AF (PeAF), and long-standing persistent AF (LSPeAF) groups.

RESULTS

A total of 164 participants (74 PAF, 47 PeAF, and 43 LSPeAF; age, 60.8 ± 9.8 years; men, 74.4%) was enrolled. The patients with PeAF and LSPeAF had worse RV4CSL (p<0.001) and RVFWSL (p<0.001) than those with PAF and reference values. Improvements in RVFWSL and RV4CSL after RFCA were significant in the PeAF group compared with the PAF and LSPeAF groups (ΔRV4CSL, 8.4% [5.1, 11.6] in PeAF vs. 1.0% [-1.0, 4.1] in PAF, 1.9% [-0.2, 4.4] in LSPeAF, p<0.001; ΔRVFWSL, 9.0% [6.9, 11.5] in PeAF vs. 0.9% [-1.4, 4.9] in PAF, 1.0% [-1.0, 3.6] in LSPeAF, p<0.001). In patients without recurrence, improvements in RVFWSL and RV4CSL after RFCA were significant in the PeAF group compared to the LSPeAF group.

CONCLUSIONS

RV systolic function is more impaired in patients with PeAF and LSPeAF than in those with PAF. RV systolic function is more improved after RFCA in patients with PeAF than in those with PAF or LSPeAF.

Exercise intolerance establishment in pulmonary hypertension: Preventive effect of aerobic exercise training

AIMS

1) Characterize the progression of exercise intolerance in monocrotaline-induced pulmonary hypertension (PH) in mice and 2) evaluate the therapeutic effect of aerobic exercise training (AET) on counteracting skeletal and cardiac dysfunction in PH.

MAIN METHODS

Wild type C57BL6/J mice were studied in two different time points: 2 months and 4 months. Exercise tolerance was evaluated by graded treadmill exercise test. The AET was performed in the last month of treatment of 4 months' time point. Cardiac function was evaluated by echocardiography. Skeletal muscle cross-sectional area was assessed by immunofluorescence. The diameter of cardiomyocytes and pulmonary edema were quantified by staining with hematoxylin-eosin. The variables were compared among the groups by two-way ANOVA or non-paired Student's t-test. Significance level was set at p < 0.05.

KEY FINDINGS

After 2 months of MCT treatment, mice presented pulmonary edema, right cardiac dysfunction and left ventricle hypertrophy. After 4 months of MCT treatment, mice showed pulmonary edema, right and left cardiac dysfunction and remodeling associated with exercise intolerance and skeletal muscle atrophy. AET was able to reverse cardiac left ventricle dysfunction and remodeling, prevent exercise intolerance and skeletal muscle dysfunction. Thus, our data provide evidence of skeletal muscle abnormalities on advanced PH. AET was efficient in inducing an anti-cardiac remodeling effect besides preventing exercise intolerance.

SIGNIFICANCE

Our study provides a robust model of PH in mice, as well as highlights the importance of AET as a preventive strategy for exercise intolerance and, skeletal and cardiac muscle abnormalities in PH.

Arterial hypertension and atrial fibrillation: standard and advanced echocardiography from diagnosis to prognostication

: Structural changes in left and right cardiac chambers that occur in arterial hypertension (AH) may lead to an increased risk of atrial fibrillation. Considering that AH is currently the most common cardiovascular disease in the general population, it represents a major risk factor for atrial fibrillation development. This review explores the complex relationship between atrial fibrillation and AH, starting from its pathophysiological basis. It focuses on the role of echocardiography in the management of hypertensive and atrial fibrillation patients, with emphasis on what should be evaluated about left ventricular remodeling, diastolic and systolic function, left atrial (LA) size and function and right ventricular deformation in patients with AH.

Long-Term Chronic Intermittent Hypobaric Hypoxia in Rats Causes an Imbalance in the Asymmetric Dimethylarginine/Nitric Oxide Pathway and ROS Activity: A Possible Synergistic Mechanism for Altitude Pulmonary Hypertension?

Chronic intermittent hypoxia (CIH) and chronic hypoxia (CH) are associated with high-altitude pulmonary hypertension (HAPH). Asymmetric dimethylarginine (ADMA), a NO synthase (NOS) inhibitor, may contribute to HAPH. This study assessed changes in the ADMA/NO pathway and the underlying mechanisms in rat lungs following exposure to CIH or CH simulated in a hypobaric chamber at 428 Torr. Twenty-four adult Wistar rats were randomly assigned to three groups: CIH2x2 (2 days of hypoxia/2 days of normoxia), CH, and NX (permanent normoxia), for 30 days. All analyses were performed in whole lung tissue. L-Arginine and ADMA were analyzed using LC-MS/MS. Under both hypoxic conditions right ventricular hypertrophy was observed (p < 0.01) and endothelial NOS mRNA increased (p < 0.001), but the phosphorylated/nonphosphorylated vasodilator-stimulated phosphoprotein (VASP) ratio was unchanged. ADMA increased (p < 0.001), whereas dimethylarginine dimethylaminohydrolase (DDAH) activity decreased only under CH (p < 0.05). Although arginase activity increased (p < 0.001) and L-arginine exhibited no changes, the L-arginine/ADMA ratio decreased significantly (p < 0.001). Moreover, NOX4 expression increased only under CH (p < 0.01), but malondialdehyde (MDA) increased (up to 2-fold) equally in CIH2x2 and CH (p < 0.001). Our results suggest that ADMA and oxidative stress likely reduce NO bioavailability under altitude hypoxia, which implies greater pulmonary vascular reactivity and tone, despite the more subdued effects observed under CIH.

Adventitial alterations are the main features in pulmonary artery remodeling due to long-term chronic intermittent hypobaric hypoxia in rats

Long-term chronic intermittent exposure to altitude hypoxia is a labor phenomenon requiring further research. Using a rat model, we examined whether this type of exposure differed from chronic exposure in terms of pulmonary artery remodeling and other features. Rats were subjected to chronic hypoxia (CH, n = 9) and long-term intermittent hypoxia (CIH2x2; 2 days of hypoxia/2 days of normoxia, n = 10) in a chamber (428 Torr, 4,600 m of altitude) for 46 days and compared to rats under normoxia (NX, n = 10). Body weight, hematocrit, and right ventricle ratio were measured. Pulmonary artery remodeling was assessed using confocal microscopy of tissues stained with a nuclear dye (DAPI) and CD11b antibody. Both hypoxic conditions exhibited increased hematocrit and hypertrophy of the right ventricle, tunica adventitia, and tunica media, with no changes in lumen size. The medial hypertrophy area (larger in CH) depicted a significant increase in smooth muscle cell number. Additionally, CIH2x2 increased the adventitial hypertrophy area, with an increased cellularity and a larger prevalence of clustered inflammatory cells. In conclusion, CIH2x2 elicits milder effects on pulmonary artery medial layer muscularization and subsequent right ventricular hypertrophy than CH. However, CIH2x2 induces greater and characteristic alterations of the adventitial layer.

Molecular pathogenesis of pulmonary arterial hypertension

Recent clinical and experimental studies are redefining the cellular and molecular bases of pulmonary arterial hypertension (PAH). The genetic abnormalities first identified in association with the idiopathic form of PAH--together with a vast increase in our understanding of cell signaling, cell transformation, and cell-cell interactions; gene expression; microRNA processing; and mitochondrial and ion channel function--have helped explain the abnormal response of vascular cells to injury. Experimental and clinical studies now converge on the intersection and interactions between a genetic predisposition involving the BMPR2 signaling pathway and an impaired metabolic and chronic inflammatory state in the vessel wall. These deranged processes culminate in an exuberant proliferative response that occludes the pulmonary arterial (PA) lumen and obliterates the most distal intraacinar vessels. Here, we describe emerging therapies based on preclinical studies that address these converging pathways.

Spleen size in idiopathic and heritable pulmonary arterial hypertension

BACKGROUND

It is unknown whether the spleen size correlates with disease severity and outcome in patients with idiopathic and heritable pulmonary arterial hypertension (PAH).

OBJECTIVES

To determine the prevalence of splenomegaly in PAH and assess whether it correlates with severity of disease and outcome.

METHODS

We identified subjects with either heritable or idiopathic PAH who had Doppler echocardiography, right-heart catheterization and computed tomography (CT) of the chest and/or abdomen that included the spleen.

RESULTS

We included 62 subjects with a mean age (±SD) of 49 (±15) years; 82% were women. Spleen dimensions were 10 (±3), 6 (±2) and 9 (±2) cm for the craniocaudal length, thickness and width measurements, respectively. The median [interquartile range (IQR)] spleen volume was 344 (225-533) cm3. Splenomegaly was observed in 52-63% of the patients, depending on the formula used. The spleen volume was not associated with clinical, echocardiographic or hemodynamic variables. Spleen volume was not associated with adjusted mortality. We studied the characteristics of the spleen during autopsy in 9 patients with idiopathic PAH who died of right-heart failure. The mean (IQR) spleen weight was 220 (151-325) g. We observed early congestion in all but 2 patients who had chronic congestion.

CONCLUSIONS

Splenomegaly of predominantly mild degree is common in idiopathic and heritable PAH. However, spleen size was not associated with clinical, echocardiographic, hemodynamic and survival data in these patients.

NT-proBNP levels in the evaluation of right ventricular dysfunction in patients with coronary artery disease and abnormal left ventricular wall motion: a magnetic resonance imaging study

BACKGROUND

Data available on the correlation of N-terminal probrain natriuretic peptide (NT-proBNP) levels and right ventricular (RV) function in patients with coronary artery disease (CAD) are limited.

OBJECTIVE

To determine the relation between plasma NT-proBNP and RV function in patients with CAD and abnormal left ventricular (LV) wall motion.

METHODS

This is a cross-sectional study. We studied 176 patients with CAD and abnormal LV wall motion. All patients underwent cardiac magnetic resonance imaging for the assessment of LV and RV function and plasma NT-proBNP analysis on the same day. Multivariable analysis was performed to evaluate the independent factors associated with RV dysfunction. Receiver-operating characteristic analysis was used to assess the use of NT-proBNP levels for the diagnosis of LV and RV dysfunction.

RESULTS

Average LV ejection fraction (LVEF) and RV ejection fraction were 37.6 and 52.0%, respectively. Median levels of NT-proBNP were 978 pg/ml. Log NT-proBNP levels had a positive correlation with age, LV and RV volume, LV and RV mass, and had a negative correlation with body size, creatinine clearance, LVEF, and RV ejection fraction. From a multivariable analysis, log NT-proBNP levels and LVEF were independently associated with RV dysfunction. From receiver-operating characteristic analysis, NT-proBNP at the levels of 1706 and 378 pg/ml was shown to detect RV dysfunction and LV dysfunction at an accuracy of 80.7 and 77.8% and area under the curve of 0.837 and 0.765, respectively.

CONCLUSION

NT-proBNP levels can be used to diagnose RV dysfunction in patients with CAD and abnormal LV wall motion.

Molecular pathogenesis of pulmonary arterial hypertension

Recent investigations have suggested that it might be possible to reverse the pathology of pulmonary arterial hypertension (PAH), a disorder that can be rapidly progressive and fatal despite current treatments including i.v. prostacyclin. This review will address the cellular and molecular processes implicated in clinical, genetic, and experimental studies as underlying the pulmonary vascular abnormalities associated with PAH. Emerging treatments are aimed at inducing apoptosis of abnormal vascular cells that obstruct blood flow and at promoting regeneration of "lost" distal vasculature.

The heart in scleroderma

The heart is one of the major organs involved in scleroderma, the involvement of which can be manifested by myocardial disease, conduction system abnormalities, arrhythmias, or pericardial disease. Additionally, scleroderma renal crisis and pulmonary hypertension lead to significant cardiac dysfunction secondary to damage in the kidney and lung. This article summarizes the types and mechanism of abnormalities in the heart in scleroderma. The concept of cardiac dysfunction in scleroderma and other rheumatologic conditions has received new interest with the advent of newer noninvasive imaging techniques, as well as the interest in detecting subclinical disease. With this increased interest in cardiac manifestations in scleroderma comes the realization that long-term studies are needed to better assess the appropriate screening and treatment in this patient population.

Utility of right ventricular tissue Doppler imaging: correlation with right heart catheterization

OBJECTIVES

The objective of this study was to correlate tissue Doppler imaging of the right ventricle (RV) with pulmonary hemodynamics in patients referred for right heart catheterization.

METHODS

Seventy subjects (mean age 54 +/- 13; 35 males) prospectively underwent tissue Doppler imaging of the RV and right heart catheterization within 1 day of each other. Peak systolic velocity and strain were measured at the RV free wall and correlated with pulmonary hemodynamics.

RESULTS

RV myocardial velocity demonstrated no correlation with any hemodynamic variable. While RV strain demonstrated significant correlation with cardiac index (r =-0.61; P < 0.001), correlations with transpulmonary gradient (r = 0.26; P < 0.05) and pulmonary vascular resistance (r = 0.30; P < 0.05) were weaker. Subgroup analysis revealed that in patients with left ventricular systolic dysfunction (n = 31), RV strain showed no correlation with any hemodynamic variable. In patients with normal left ventricular systolic function (n = 39), correlations were significant between RV strain and mean pulmonary artery pressure (r = 0.59; P < 0.001), pulmonary vascular resistance (r = 0.60; P < 0.001), and cardiac index (r =-0.67; P < 0.001).

CONCLUSIONS

RV myocardial strain correlates significantly with pulmonary hemodynamics in patients with pulmonary hypertension and normal left ventricular function. However, there is no correlation with RV performance in patients with left ventricular dysfunction.