Left ventricular outflow tract obstruction following aortic valve replacement: A review of risk factors, mechanism, and management

The presence of dynamic left ventricular outflow tract obstruction (LVOTO) can complicate the postoperative course of patients undergoing surgical aortic valve replacement (AVR). The phenomenon of LVOTO is a consequence of an interplay of various pathoanatomic mechanisms. The prevailing cardiovascular milieu dictates the hemodynamic significance of the resultant LVOTO in addition to the anatomical risk factors. A thorough understanding of the predisposing factors, mechanism, and hemodynamic sequel of the obstruction is pivotal in managing these cases. A comprehensive echocardiographic examination aids in risk prediction, diagnosis, severity characterization, and follow-up of management efficacy in the setting of postoperative LVOTO. The armamentarium of management modalities includes conservative (medical) and surgical options. A stepwise approach should be formulated based on the physiological and anatomical substrates predisposing to LVOTO. The index phenomenon occurs more frequently than appreciated and should be considered when the post-AVR patients exhibit hemodynamic instability unresponsive to conventional supportive measures. The present article provides an overview of various peculiarities of this under-recognized phenomenon in the context of the perioperative management of patients undergoing AVR.

Clinical and morphological features of hypertrophic cardiomyopathy in Korean patients

Thirty three cases of hypertrophic cardiomyopathy (HCMP) were reviewed to estimate the relative frequencies of the subtypes of HCMP and to clarify whether there is any racial difference in clinical and morphological features of HCMP. The diagnosis was made by echocardiography, cardiac catheterization and left ventriculography. Twenty four patients underwent coronary angiogram. Numbers of cases by the types of HCMP were 20 (61%) with asymmetrical septal hypertrophy (ASH), 11 (33%) with apical hypertrophy (APH) and 2 (6%) with midventricular hypertrophy (MVH). Mean ages of the patients with APH, ASH and MVH were 54, 46 and 31 years respectively, and the differences were statistically significant (p less than 0.05). The giant negative T wave on electrocardiogram was seen in 4 patients (20%) of ASH and 5 patients (45%) of APH. On echocardiogram mean ratio of interventricular septal to left ventricular posterior wall thickness was 1.9 in ASH, 1.2 in APH and 1.6 in MVH, and the differences were statistically significant (p less than 0.05). All patients with APH showed "spade of ace" deformity in left ventriculography. Coronary angiograms were normal in all patients who had the procedure. Our study showed high frequency of APH of which characteristics were similar to those of the Japanese type APH.