Concentric remodelling preserves right ventricular function in PAH
medwireNews: Systolic function is better preserved in patients with idiopathic pulmonary arterial hypertension (PAH) if they have a higher right ventricle (RV) mass-to-volume ratio, research shows.
“This finding is of great interest because it may allow clinicians to identify patients at higher risk of development of right heart failure”, say researcher Roberto Badagliacca (Sapienza University of Rome, Italy) and colleagues.
They add that studies are now needed to see if the RV mass-to-volume ratio can predict clinical deterioration in PAH patients.
The 60 patients with idiopathic PAH in the study had a normal distribution of RV mass-to-volume ratio, so the team divided them at the median of 0.46.
Patients at or below the median had more eccentric RV remodelling, relative to patients above the median, reflected in a significantly higher left ventricular (LV) end-systolic and end-diastolic eccentricity index. They had significantly larger RV end-systolic and diastolic areas and volumes, and also had significantly higher filling pressure, as indicated by a higher right atrial pressure (9.8 vs 5.5 mmHg).
The increased LV eccentricity index in these patients is “the expression of increased wall stress, as a result of increased RV dimensions and filling pressure, inducing further ventricular dilatation and maintaining a vicious circle of positive feedback”, write the researchers in The Journal of Heart and Lung Transplantation.
The two groups had similar pulmonary vascular resistance, mean pulmonary arterial pressure, and pulmonary arterial compliance. Yet patients with eccentric remodelling had poorer systolic function, including a smaller RV ejection fraction (33 vs 39%) and right ventricular fractional area change (34 vs 43%), more pericardial effusion (38 vs 5%) and lower tissue velocity and contractility.
This poor function in patients with eccentric remodelling, the team explains, is because for a given intraventricular pressure, “the radius of the ventricle is increased compared with wall thickness, determining a greater increase in wall stress.”
Patients above the median RV mass-to-volume ratio represented those with more concentric RV remodelling in response to an increased afterload; in other words, wall thickness increased without excessive increase in the radius of the ventricle.
This “protects the ventricle from abnormally high wall tension, suggesting a favorable adaptation to increased RV afterload”, say Badagliacca et al.
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By Eleanor McDermid, Senior medwireNews Reporter