ScholarWorks@중앙대학교

초록

Introduction: Clinical characteristics of mid-ventricular obstruction (MVO) are poorly understood, especially in patients without significant obstruction. Hypothesis: This study investigated the frequency, clinical and laboratory characteristics, and management of MVO. Methods: A total of 8922 patients in whom transthoracic echocardiography was performed in 2014 were reviewed for the frequency of MVO. The definition of MVO was a pressure gradient within the left ventricle (LV) ≥ 2 mmHg at rest or ≥ 5 mmHg during Valsalva maneuver, however, not in LV outflow track. Patients with MVO were divided into two groups; the control group (n=12) and intervention group (n=16). The intervention consisted of β-blocker, verapamil, and aortic valve replacement. In 10 patients, MVO was compared between at acute medical status and during clinically stable condition. Results: MVO was documented in 60 of 8922 patients (0.67%) and more prevalent than basal septal (0.24%) or apical (0.28%) hypertrophic cardiomyopathy. Significant obstruction (dP≥30 mmHg) at rest was observed only in 9 patients (0.10%). Cardiac symptoms were observed in 53% of patients. Pressure gradient was not different between patients with and without symptoms (p=0.15). There were no specific electrocardiographic findings. In echocardiography, most patients showed isolated basal septal hypertrophy (sigmoid septum, 92%), mid-septal hypertrophy (87%), and prominent papillary and/or accessory muscles. The shape of Doppler wave was either asymmetrical or dagger appearance according to pressure gradient. The interventions reduced pressure gradients (p=0.003) and improved symptoms in 75% of patients compared with only 1 patient (8%, p<0.000) in the control group. Mid-ventricle pressure gradients with acute medical illness were higher at rest (p<0.005) and during Valsalva maneuver (p<0.05) compared with those during stable state. Conclusions: MVO is not so rare and quite variable in hemodynamics and clinical symptoms. Several echocardiographic findings are helpful for diagnosis. Symptoms are frequently observed regardless of the severity of the obstruction and well controlled by specific therapy.