Echocardiographic Features of Pigs with Spontaneous Hypertrophic Cardiomyopathy

Ultrasonography is one of the most common, noninvasive techniques used for cardiovascular diagnosis because it provides reliable information and enhances patient safety. Two-dimensional (2-D) and M-mode echocardiography is conducted to assess the severity and distribution of myocardial hypertrophy. Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease that has variable manifestations because interactions between the many facets of systolic and diastolic dysfunction of the heart are complex. The objective of the study reported here was to characterized clinical HCM in pigs. A commercial Vingmed (CFM-800) 3.25 MHz transducer was used to perform 2-D and M-mode echocardiography. Experimental pigs (about 100 kg in body weight) were anesthetized and positioned in left lateral recumbency.

Echocardiographic images (2-D) were acquired in parasternal short-axis and long-axis views. The 2-D images provided M-mode under direct anatomic visualization. The pigs were sacrificed for pathologic study after echocardiographic examination. In typical HCM cases (n = 8), the interventricular septum thickness increased, the left ventricular (LV) end-systolic and end-diastolic dimensions decreased, and the left atrial dimensions and the indexes of systolic function, such as ejection fraction and velocity of fiber shortening, increased. The LV outflow tract narrowed, particularly when gross upper septal hypertrophy was evident. Moreover, systolic cranial motion (SCM) of the septal leaflet of the mitral valve was observed. Doppler evidence of mitral regurgitation often was associated with SCM. The echocardiographic findings from pigs with HCM resembled those from humans. Thus, porcine HCM may serve as a spontaneous animal model for the study of HCM in humans.