Estimation of right ventricular mass by two-dimensional echocardiography

Novel Echocardiographic Algorithm for Right Ventricular Mass Quantification: Cardiovascular Magnetic Resonance and Clinical Prognosis Validation

BACKGROUND

Right ventricular hypertrophy (RVH) provides a key remodeling index alterable by pulmonary hypertension. Although echocardiography commonly integrates linear wall thickness and chamber dimensions to quantify left ventricular remodeling, the utility of an equivalent right ventricular (RV)-based approach is unknown.

METHODS

This was a retrospective analysis of 200 patients undergoing transthoracic echocardiography and cardiac magnetic resonance (CMR) within 30 days (median = 3 days; interquartile range, 15 days), stratified by echocardiography-quantified pulmonary artery systolic pressure (<35, 35 to <55, 55 to <75, or ≥75 mm Hg). Echocardiographic assessment included RV linear dimensions in parasternal long-axis and apical four-chamber views and wall thicknesses in parasternal long-axis, four-chamber, and subcostal views. Subcostal wall thickness was integrated with chamber diameters to calculate RV mass, which was tested in relation to CMR-quantified RV mass and all-cause mortality.

RESULTS

Echocardiography-based quantification of all linear dimensions was feasible in 95% of patients (190 of 200). RV wall thicknesses in all orientations increased in relation to pulmonary artery systolic pressure (P < .001) and was greater among patients with, versus those without, CMR-evidenced RVH (P < .001 for all). Correlations between echocardiography and CMR were greatest for RV basal diameter (r = 0.73), RV subcostal wall thickness (r = 0.71), and global RV mass (r = 0.82; P < .001 for all). Echocardiography-derived global RV mass cutoffs were established in a derivation cohort and tested in a validation cohort. Results demonstrated good sensitivity and specificity (75.5% and 74.0%, respectively) in relation to CMR-quantified RVH. During follow-up (median, 4.2 years), 18% of patients (n = 36) died. Echocardiography-evidenced RVH (hazard ratio, 1.98; 95% CI, 1.09-3.88; P = .048) conferred similar mortality risk compared with RVH on CMR (hazard ratio, 2.41; 95% CI, 1.22-4.78; P = .01).

CONCLUSIONS

Echocardiography-quantified RV parameters provide a robust index of RV afterload. Global RV mass calculated using a novel echocardiographic formula based on readily available linear indices yields good diagnostic performance for CMR-evidenced RVH and confers increased mortality risk.

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.

Reversible pulmonary trunk banding III: Assessment of myocardial adaptive mechanisms—contribution of cell proliferation

OBJECTIVES

Rapid ventricular conditioning induced by pulmonary artery banding has been recommended for patients with transposition of the great arteries who have lost the chance for the arterial switch operation or whose systemic (right) ventricle failed after the atrial switch. The present study was designed to experimentally evaluate 2 types of pulmonary artery banding (continuous and intermittent) and verify histologically the changes (hypertrophy or hyperplasia or both) of cardiomyocytes and vascular and interstitial cells from the stimulated ventricle beyond the neonatal period.

METHODS

Twenty-one goats, 30 to 60 days old, were divided into 3 groups, each comprising 7 animals, as follows: control group (no surgical procedure); continuously stimulated group (systolic overload maintained for 96 hours); and intermittently stimulated group (4 periods of 12-hour systolic overload, alternated with a resting period of 12 hours). The animals were then killed for histologic and immunohistochemical analysis of the hearts. Murine monoclonal antibody Ki-67 was used as a proliferation cell marker. Myocardial collagen area fraction was determined by Sirius red staining.

RESULTS

For both stimulated groups, a significant increase occurred in right ventricular cardiomyocytes and respective nuclei diameters compared with the controls (P < .05). The number of Ki-67-positive cardiomyocytes and interstitial/vessel cells from the right ventricle was augmented in both trained groups in relation to the left ventricle (P < .05). There was no significant difference in the right ventricular collagen area fraction from both trained groups compared with controls.

CONCLUSIONS

Irrespective of the shorter training time (periods of overload intercalated with resting), the intermittent stimulation regimen was able to produce a similar training of the subpulmonary ventricle compared with the continuous stimulation regarding mass acquisition, cell hypertrophy, and hyperplasia.

Noninvasive Cardiac Imaging in Pulmonary Hypertension

Pulmonary artery hypertension is a rare disease with significant morbidity and mortality. Initial and serial noninvasive assessment of these patients can be accomplished with transthoracic echocardiography and/or cardiac magnetic resonance imaging. These complementary techniques provide the structural and functional information required to care for patients with pulmonary artery hypertension and are discussed in this review.