Acute Right Ventricular (RV) Failure Presenting As Isolated Right-Sided Colitis.

Ischemic colitis constitutes about half of mesenteric vasculopathies, and it shares a similar pathophysiologic process with acute and chronic mesenteric ischemia. These, in turn, can be divided into occlusive and nonocclusive mesenteric ischemia (NOMI). We present this case of a patient presenting with abdominal pain secondary to right-sided colitis, initially presumed to be infectious, but later attributed to localized NOMI. The correlation between localized NOMI, specifically right-sided colitis, and right ventricular (RV) failure has not been well described in the literature. NOMI, in general, is suspected to be secondary to splanchnic vasoconstriction, which results from sympathetic stimulation and renin-angiotensin-aldosterone system (RAAS) activation. Additionally, patients with RV failure have been shown to develop intestinal congestion due to elevated right atrial pressure (RAP), leading to bowel wall thickening and impaired mesenteric venous drainage, which may further contribute to ischemia. This mechanism suggests that both arterial hypoperfusion and venous congestion may play a role in the pathogenesis of right-sided ischemic colitis in RV failure. The predominance of ischemia in the right colon, rather than in classical watershed areas, may be attributed to preferential vasoconstriction of the superior mesenteric artery (SMA), which supplies the right colon, as well as localized venous congestion impairing mesenteric drainage in this region. Individual variability in vascular anatomy and autoregulatory responses could also contribute to this atypical presentation. This case highlights a potentially underrecognized association between RV dysfunction and right-sided ischemic colitis, emphasizing the interplay of low cardiac output, mesenteric hypoperfusion, and venous congestion. Given the absence of direct studies on this relationship, further research is needed to better understand its clinical significance.