Hypertrophic cardiomyopathy in pigs: quantitative pathologic features in 55 cases

Area of Science:

• Cardiovascular Pathology
• Veterinary Cardiology
• Comparative Pathology

Background:

• Hypertrophic cardiomyopathy (HCM) is a primary heart muscle disease affecting various species.
• Understanding spontaneous animal models is crucial for elucidating human cardiovascular diseases.

Purpose of the Study:

• To characterize naturally occurring hypertrophic cardiomyopathy (HCM) in pigs.
• To evaluate the pig as a potential animal model for cardiovascular research.

Main Methods:

• Histopathological examination of hearts from 55 pigs diagnosed with HCM.
• Comparative analysis of heart weight, ventricular septum thickness, and left ventricular free wall thickness against control groups (46 purebred and 64 hybrid pigs).
• Assessment of collagen content and connective tissue abnormalities using silver impregnation stains.

Main Results:

• Pigs with HCM exhibited significantly heavier hearts (p < 0.001) and increased heart weight/body weight ratios compared to controls.
• Significant thickening of the ventricular septum (VS) and left ventricular free wall (LV) was observed in HCM pigs.
• Histology revealed muscle cell disorganization, abnormal coronary arteries, myocardial fibrosis, and increased collagen content (47-52% higher) in HCM hearts.

Conclusions:

• Spontaneous porcine hypertrophic cardiomyopathy (HCM) presents with gross and histological features strikingly similar to human, feline, and canine HCM.
• The pig serves as a novel and significant animal model for cardiovascular investigators studying HCM.
• Abnormalities in connective tissue and matrix organization are key features of porcine HCM.