The spectrum of congestion in heart failure: underlying pathophysiology and diagnostic strategies

Congestion is the main driver of heart failure (HF) recurrence and its relief remains the primary therapeutic target during acute management. In most studies achievement of decongestion is evaluated by clinical examination. The lack of accurately recognizing congestion, together with the incomplete understanding of its underlying pathophysiological mechanisms, may lead to a substantial discordance between de-congestion and mortality risk reduction. To avoid these concerns, a classification dividing congestion between intra vs. extravascular, has been recently purposed but it is still based on clinical signs rather than an integrated diagnostic assessment. Additionally, across several studies, congestion is evaluated at various time moments and with different diagnostic methods. Over the last decades new approaches combining ultrasonographic evaluation, invasive measurement and biomarkers have been suggested, although a universal multi-parametric diagnostic strategy is not extensively applied. The complex mechanisms and dynamic nature of fluid retention, venous capacitance, lymphatic conditions and interstitial space integrity are relevant components which contributes to create further misunderstanding. The numerous cardiac and extracardiac factors potentially involved in congestion onset and recurrence need to be addressed during the evaluation. In this paper we would gather potential approaches for early congestion detection according to HF profile, based on the assumption that hemodynamic congestion and increased cardiac pressure does not necessarily coincide with systemic fluid retention. Graphical Abstract