Hypertrophic cardiomyopathy (HCM) is an auto-somal dominant trait that affects 1 in 500 adults. Many patients are unaware of the condition, and some will present with SCD as an initial manifesta-tion. Symptoms include dyspnea, exercise intoler-ance, palpitations, and chest pain. Clinically, HCM is detected by the murmur of dynamic left ventricu-lar outflow tract (LVOT) obstruction in late systole. Symptomatic patients frequently have a thickened intraventricular septum of 20 to 30 mm. Mutations in the genes that code for the cardiac sarcomeres and their supporting proteins are implicated. The myo-cardium of the intraventricular septum is abnormal, and many patients can develop diastolic dysfunction and SCD without pronounced dynamic obstruc-tive gradients. During systole, the anterior leaflet of
the mitral valve abuts the intraventricular septum (Figure 21–6), producing obstruction and a late systolic murmur.
Perioperative management is aimed at mini-mizing the degree of LVOT obstruction. This is accomplished by maintaining adequate intravas-cular volume, avoiding vasodilatation, and reduc-ing myocardial contractility through the use of β-blockers.