Critical Hypoplastic Mitral Stenosis and Subaortic Obstruction in Neonates with Coarctation (Shone’s Complex), Ventricular Septal Defect, and Minimal LV hypoplasia

Objectives: Patients with multilevel obstructions of left heart structures have a high risk for neonatal morbidity and mortality. We analyzed and demonstrate the morphological spectrum of six neonatal autopsy cases with Shone’s complex and ventricular septal defect (VSD), considering diagnosis and surgery.

Methods: Six heart specimens with coarctation (CoA) and VSD were identified in the anatomical collection of the German Heart Center (1974–1992). Examination included measurements of length from apex to AV-valves and semilunar valves, heart valve diameter, and thickness of right and left ventricular myocardium.

Result: Mean age at death was 15 days (5–33 days). Findings present in all hearts: normal connections of atria/ventricles/great arteries, CoA combined with functionally significant aortic arch hypoplasia and VSD, one half was perimembraneous–inlet, the other half noncommitted muscular trabecular, no supramitral ring stenosis, no endocardial fibroelastosis of LV. Associated significant anomalies in all hearts: hypoplastic mitral stenosis, with Shone’s complex “forme fruste” of parachute MV in one half of the cases, subaortic stenosis with prominent “bulge” of the anterior-superior muscular LV-outlet septum (mean thickness, 12.4 mm). The mean LV/RV length ratio of both inlet and outlet of equally 0.9 confirmed the insignificance of LV hypoplasia. By contrast, the mean diameter ratio of the right/left AV-valves of 0.5 and 0.6 of the semilunar valves demonstrated the significant hypoplasia of both mitral and aortic valves. Four cases presented with status postsurgery: resection of CoA and ductus closure four of four, with concomitant pulmonary artery banding in three-fourths, and LV-outlet septum myectomy one-fourth.

Conclusion: Our results imply that early intervention of multilevel obstruction may be crucial for survival of neonates with multiple left heart obstructive lesions and nearly normal sized left ventricle associated with VSD. Besides the CoA, special attention should be payed to the hypoplastic mitral stenosis, and the LVOT-obstructing muscular “bulge.”