Title : Intact Right Sinus of Valsalva Aneurysm Dissecting the Interventricular Septum: A Rare Cause of Complete Heart Block in Post-Mitral Valve Replacement
Abstract:
Right sinus of Valsalva aneurysm (RSOVA) dissecting into the interventricular septum (IVS) without free rupture is an exceedingly rare and potentially fatal aortic root complication. Mechanical compression of the bundle of His by an intact dissecting RSOVA causing complete heart block (CHB) is exceptionally uncommon, and its occurrence in a patient with rheumatic heart disease (RHD), mitral stenosis (MS), chronic myocarditis, and a metallic mitral valve replacement (MVR) placed in 2024 represents a unique convergence of pathologies. We report this rare dual emergency in a 24-year-old male.
The patient had longstanding RHD with MS and chronic myocarditis, with LV systolic function persistently reduced at 35–40% for the preceding two years. He presented acutely with progressive dyspnoea, presyncope, and haemodynamic deterioration. On examination, a harsh pansystolic 5/6 murmur was audible at Erb's point. Electrocardiography revealed CHB. Transthoracic echocardiography showed the metallic mitral prosthesis in situ with intravalvular regurgitation and a mean pressure gradient of 20/16 mmHg, mildly dilated left atrium (43 mm), and a right coronary cusp RSOVA dissecting into the IVS with aneurysm mouth 1.4 cm and mid-cavity dimension 2.4 cm. Notably, there was mild to moderate mitral regurgitation but no paravalvular leak, excluding prosthetic dehiscence. Global LV hypokinesia with moderate systolic dysfunction (LVEF 35–40%) was unchanged from prior. Additional findings included mild aortic regurgitation, mild eccentric tricuspid regurgitation, mild pulmonary hypertension (PASP 37 mmHg), and intact interatrial and interventricular septa without free rupture.
The diagnostic impression was RSOVA-IVS dissection mechanically compressing the conduction system causing CHB, superimposed on chronic RHD-related myocarditis and metallic prosthetic mitral valve disease. CHB combined with acute pulmonary oedema (APO) from depressed LV function and elevated prosthetic valve gradients constituted dual life-threatening indications for urgent surgical intervention.
The patient underwent emergency on-pump operative repair. Surgical management comprised obliteration of the RSOVA with a pericardial patch repair, restoring normal aortic root architecture and decompressing the conduction system. Intraoperative epicardial pacing leads were placed for conduction system support. Postoperative transthoracic echocardiography showed a very small jet of leak across the patch; however, the size of the IVS aneurysm due to the RSOVA was not increasing. The patient gradually reverted to sinus rhythm and was haemodynamically stable within one day.
At four-week follow-up, transoesophageal echocardiography demonstrated a decrease in the size of the patch leak and a reduction in the size of the RSOVA. No thromboembolic events or major haemorrhagic complications were recorded.
This case highlights the extreme rarity of intact RSOVA-IVS dissection causing CHB without rupture, and underscores the importance of systematic aortic root interrogation during echocardiographic surveillance in post-MVR patients. On-pump pericardial patch repair with epicardial pacing is an effective strategy, with favourable early structural and rhythm outcomes.
Keywords: right sinus of Valsalva aneurysm; interventricular septum dissection; complete heart block; acute pulmonary oedema; rheumatic heart disease; mitral stenosis; myocarditis; metallic mitral valve replacement; pericardial patch repair; epicardial pacing; on-pump surgery
