Cardiovascular Proportionality of Modern Pigs : Are we breaking the allometric scaling laws ?

We have investigated, the proportionality of the cardiovascular system of modern pigs using allometric scaling laws. We found that heart weight scales with body weight in all examined weight categories (25-350 kg) and in animals under 100 kg also stroke volume and cardiac output scales with body weight, according to allometric scaling laws.
But we found in heavier pigs (> 150 kg) that heart volumes like end-diastolic volume, stroke volume and cardiac output were relatively low regarding allometric scaling laws. The disproportionally low stroke volume was not the result of systolic dysfunction but of diastolic perturbations, likely as a result of an increased myocardial interstitial collagen content in conjunction with marked elevations in aortic blood pressure.
These findings for one thing, underpin the growing concerns about intrinsic cardiovascular factors in modern pigs. In addition, we can conclude that heavy swine, as a result of these pathophysiological cardiovascular alterations, may be of value as an animal model to study cardiovascular disease, in particular heart failure preserved ejection fraction (HFpEF) in humans.