Adult Yucatan Minipigs Research Articles

Induction of neointimal hyperplasia by coronary angioplasty balloon overinflation: Comparison of feeder pigs to Yucatan minipigs

We evaluated the use of simple balloon overinflation to induce neointimal hyperplasia in a porcine model of coronary artery restenosis. By using standard percutaneous transluminal coronary angioplasty techniques, left anterior descending (LAD) and/or left circumflex (LCX) coronary arteries of either juvenile feeder pigs or adult Yucatan minipigs were intentionally overinflated. Four weeks later, resultant neointimal hyperplastic responses (neointima/media area; NI/M were quantitated morphometrically. At all ballooned sites neointimal hyperplasia occurred only when the internal elastic lamina (IEL) was ruptured; the degree of hyperplasia correlated directly with the injury index, that is, the percentage of IEL circumference that tractured ( r = 0.74; n = 25; p < 0.05). Despite similar injury indexes in the LAD bed, there was a trend ( p = 0.07; analysis of variance) toward greater NI/M ratios in the Yucatan minipig versus the feeder pig group (1.14 ± 0.21 vs 0.73 ± 0.09, n = 7/group). We found no such trend in the LCX bed, where the injury index (25.7% ± 3.5%) was significantly greater than that of the LAD (18.2% ± 1.2%, p < 0.05). If variations in balloon-induced vascular injury are accounted for, the technique of balloon overinflation of coronary arteries should prove useful in testing potential antirestenotic agents in either adult or juvenile pigs.

Regional cerebral blood flow with manual internal cardiac massage versus direct mechanical ventricular assistance

Previous studies have not discerned the best method for generating regional cerebral blood flow during internal cardiac massage. We hypothesized that regional cerebral blood flow generated by a mechanical method--direct mechanical ventricular assistance (DMVA)--would be superior to manual internal cardiac massage (MAN). Twelve adult Yucatan minipigs weighing more than 44 kg each were studied. Swine were instrumented for regional cerebral blood flow measurements using tracer microspheres. After 15 minutes of ventricular fibrillation, swine were randomized to receive either MAN or DMVA. Regional cerebral blood flow was measured during normal sinus rhythm and at one minute (VF-1) and six minutes (VF-2) after initiation of circulatory support. Regional cerebral blood flow values were compared using a Wilcoxon rank sum test. During VF-1, there was a tendency for DMVA to produce greater regional cerebral blood flow than MAN, although these differences were not statistically significant (DMVA vs MAN as mL/min/100 g): cerebral cortex, 28 versus 11; cerebellum, 49 versus 22; midbrain, 43 versus 16; pons, 55 versus 18; medulla, 55 versus 19; and spinal cord, 33 versus 10. During VF-2, DMVA produced greater regional cerebral blood flows than were produced by MAN: cerebral cortex, 39 versus 12 (P less than .06); cerebellum, 58 versus 20 (P less than 0.5); midbrain, 50 versus 18 (P less than .05); pons, 52 versus 22 (P less than .06); medulla, 53 versus 20 (P less than .05); and spinal cord, 31 versus 12 (P less than .05). DMVA produces greater regional cerebral blood flow than is produced during MAN after 15 minutes of ventricular fibrillation. DMVA is effective at maintaining regional cerebral blood flow after a prolonged cardiac arrest.