Chronic Right Heart Failure: Pathogenesis, Haemodynamic Foundations, and a Pragmatic Diagnostic Algorithm.

Chronic right heart failure (RHF) is a complex, progressive syndrome that remains underrecognized and inadequately defined in current clinical guidelines, where it is often relegated to a secondary complication of left-sided heart disease. Because the thin-walled right ventricle (RV) is well adapted to maintain pressures within the highly distensible venous system well below plasma oncotic pressure but poorly equipped to sustain pressure overload, when myocardial failure supervenes, conventional RV systolic indices frequently fail to capture the very essence of the syndrome. This review clarifies the distinct pathophysiological and haemodynamic foundations of chronic RHF, framing it fundamentally as the heart's inability to decongest the systemic venous circulation. We highlight how backward failure, rather than isolated RV systolic dysfunction, drives systemic and multi-organ congestion. To bridge existing diagnostic gaps, we propose a pragmatic, diagnostic algorithm. Under this framework, a Definite Diagnosis of chronic RHF requires evidence of elevated right atrial/central venous pressures-defined as clinically raised jugular venous pressure plus an echocardiographic dilated inferior vena cava (>21 mm with <50% collapse)-alongside at least one of four minor criteria: (1) systemic or visceral congestion (e.g., persistent oedema, congestive hepatomegaly); (2) echocardiographic RV systolic dysfunction (TAPSE < 17 mm, FAC < 35%, S' < 9.5 m/s; RV free-wall strain > -20%); (3) non-invasive signs of pulmonary hypertension (TRV > 2.8 m/s); or (4) impaired RV-pulmonary arterial coupling (TAPSE/PASP ratio < 0.35). By centering diagnosis on systemic venous hypertension as a result of right heart backward failure rather than isolated RV metrics, this framework offers a coherent, readily applicable tool for diagnosing chronic RHF in routine clinical practice.