Repeated Balloon Inflations Do Not Diminish ST Segment Elevation even though Coronary Collateral Recruitment Is Promoted in Pigs

Abstract

Objective: Attempts to demonstrate preconditioning during repeated angioplasty balloon inflations (BIs) have not been universally successful. The main obstacle is that the first BI is unreliable, due to the variable degrees of occlusion by the deflated balloon. In the present study, we examined whether ST segment elevation decreases and evaluated its relation to collateral recruitment during repeated angioplasty BIs in the pig. Methods and Results: Twenty male pigs, 7 months old, under general anesthesia, underwent 3 repeated BIs of 120 s, with a 5-min interval between them, in the left anterior descending artery or the right coronary artery. A pressure wave wire was used for the measurement of coronary wedge pressure and to obtain the intracoronary ST segment elevation. Intracoronary ST segment elevation was 1.97 ± 0.76 mV during the 1st BI, 2.09 ± 0.82 mV during the 2nd BI and 1.84 ± 0.82 mV during the 3rd BI (p = n.s.). Coronary wedge pressure was 12 ± 6, 18 ± 18 and 20 ± 20 mm Hg (p < 0.05 vs. 1st BI) during the 3 BIs, respectively. Conclusion: Repeated BIs do not diminish ST segment elevation in the pig model, even though coronary collateral recruitment is promoted.

The bottleneck stent model for chronic myocardial ischemia and heart failure in pigs

“…I: at 5 wk, myocardial perfusion is globally lower than at 1 wk. J: average sizes of 15 O-radiowater PET perfusion defects show that approximately half of the LV is affected in this model (by either infarction or reversible ischemia). K: 18 F-FDG PET shows 28 and 36% of partially and nonviable myocardium of the LV, respectively.…”

“…In the dog model of intermittent 2-min coronary occlusions (8 times per day over 20 days) by a percutaneous pneumatic occluder, it was shown that the rate of collateral development was slower in dogs with poorer endogenous collaterals (7). Furthermore, the three repeated brief coronary occlusions by a balloon inflation appeared to recruit some collaterals in a porcine model but did not diminish ST-segment elevation (15), demonstrating that the preexisting collateral anastomoses need to enlarge over a few days to prevent transmural myocardial infarction in pigs. In our model, the few newly formed collaterals seen at 1 wk via angiography in pigs with transmural infarction were regressed by 4 wk, probably because infarcted myocardium needs only little blood flow, which corroborates the findings of a recent clinical study (3).…”

“…However, chronic myocardial ischemia and extensive infarction are difficult to achieve in pigs for several reasons. Most importantly, pigs have only a few endogenous collateral anastomoses, making them susceptible to transmural myocardial infarction (15,19). Pigs are also remarkably vulnerable to sudden cardiac death caused by ventricular arrhythmias in case of a large ischemic area.…”

“…4; Supplemental Videos [11][12][13][14][15]. Similarly to the LCX model, collaterals in the LAD model had been formed almost completely by 1 wk after stenting.…”

“…PET and computed tomography (CT) studies were performed with Discovery VCT hybrid PET/CT scanner (GE Medical Systems, Milwaukee, WI). Myocardial perfusion was evaluated by PET with 15 O-radiolabeled water (957 Ϯ 78 MBq) both at rest and during adenosine stress (200 g·kg Ϫ1 ·min Ϫ1 iv infusion) early (2-4 days) and late (5 wk) after stenting as previously described (21). Myocardial viability was assessed by 18 Animals stented in the left anterior descending coronary artery (LAD) for positron emission tomography (PET) imaging received dual antiplatelet therapy (DAPT) for 1 wk after bottleneck stenting to demonstrate the patency of the stent and inducible ischemia.…”