Comment
Residual subaortic obstruction is a common cause of persistent symptoms following septal reduction therapy (SRT) and may be more common following ASA compared to surgical myectomy.  As illustrated in our patient, however, other cardiac problems may contribute to poor functional outcome post procedure.  Patients with HCM and midventricular obstruction have effort-related symptoms that are often indistinguishable from those caused by subaortic obstruction, and it is important to identify this before SRT.  Combined subaortic and midventricular obstruction is difficult to eliminate with ASA and may require injection in multiple septal perforating arteries with excess volume of alcohol.  For surgical myectomy in patients with both subaortic and midventricular obstruction, we prefer transapical approach for mid ventricular septal resection combined with transaortic exposure for the subaortic myectomy.[3]
Constrictive pericarditis (CP) causes impaired diastolic ventricular filling, [4] and it may be difficult to distinguish the symptoms of dyspnea and fatigue between CP and HCM, There were no antecedent events in our patient that might have caused constriction and raised suspicion regarding the diagnosis.  Detailed hemodynamic assessment did suggest constrictive pericarditis and this important finding supported proceeding with operation. [5]
Extensive calcification of the ascending aorta, ”porcelain aorta,” is prevalent in the elderly and may reflect increased arterial stiffness.[6]. Of more importance to the surgeon is the potential difficulty in aortic clamping and securing hemostasis following simple aortotomy when extensive plaque is present in the ascending and sinus portions of the aorta. In the present case, excision of the ascending aorta and graft replacement appeared to be the safest method for exposing the subaortic area and for ensuring hemostasis.