Increase in collateral blood flow following repeated coronary artery occlusion and nitroglycerin administration.

Abstract

SUMMARY. The effects of occlusion, reperfusion, reocclusion (n = 13), and nitroglycerin (n = 10) on regional transmural myocardial collateral blood flow was tested in conscious dogs in which collateral development was stimulated by partial stenosis of the left circumflex coronary artery. Hemodynamics and collateral blood flow were measured during the awake state using 9-/im radioactive microspheres. Regional transmural flow was measured during transient occlusion of the circumflex artery at 7 and at 14 days postoperatively. On the 14th postoperative day, two sets of circumflex occlusions and blood flow measurements were carried out. The first set consisted of two occlusions separated by 15 minutes. The second set performed 2 hours later included two occlusions, separated by 15 minutes, and nitroglycerin administration. Mean collateral blood flow increased significantly (P = 0.002) from 0.10 ± 0.07 ml/min per g on day 7 to 0.25 ± 0.18 ml/ min per g on day 14. A significant increase in mean collateral blood flow from occlusion one to two was observed (0.28 ± 0.17 to 0.37 ± 0.22 ml/min per g, P = 0.005). Mean collateral flow increased significantly (P = 0.01) between pre-to post-nitroglycerin occlusions, 0.28 ± 0.20 to 0.46 ± 0.32 ml/min per g. Although this increase appeared to be greater than during the first set of occlusions, it did not reach statistical significance (P = 0.08). These data indicate that when immature collaterals are present, occlusions, reperfusion, and reocclusions of a major coronary artery produce augmentation in collateral flow. This must be considered in evaluating interventions which may alter collateral flow. (CircRes 54: 204-207, 1984) IN the event of coronary artery occlusion, collateral vessels can provide an alternate source of blood flow. Little is known, however, about the functional physiology of immature collateral vessels. If a partially stenosed major coronary artery is suddenly totally obstructed, the integrity of the myocardium will become entirely dependent upon the functional adequacy of the collateral vessels. It is important, therefore, to determine whether immature collateral vessels function to deliver a fixed maximal amount of flow immediately after total occlusion of the stenosed coronary, or if blood flow to the collateraldependent area can be augmented by prior brief episodes of total occlusion, or by drug administration.In order to carry out these studies, a model was developed in our laboratory in which collateral vessel growth was stimulated by partial stenosis of the left circumflex coronary artery. In our model, the blood flow to a region of myocardium was supplied by both the partially stenosed circumflex artery, and by immature but developing collateral vessels. During complete temporary occlusion of the circumflex artery, the immature collaterals were the primary source of flow to this area of myocardium.The primary aim of the study was to determine whether (after a brief occlusion of a major coronary artery and reperfusion), a second occlusion would elic...

Nitroglycerin and Epinephrine Improve Coronary Perfusion Pressure in a Porcine Model of Ventricular Fibrillation Arrest: A Pilot Study

“…However, CPP in animals receiving the combination of epinephrine and nitroglycerin was elevated compared to those receiving epinephrine alone. This is in accordance to previous studies where a significant difference in CPP was observed (18,19). Although the precise mechanism by which nitroglycerine exerts these beneficial effects is unknown, we can only postulate that the reduced afterload is responsible.…”

The use of mice and rats as animal models for cardiopulmonary resuscitation research

“…Due to the numerous adverse cardiovascular effects of vasopressin and adrenaline and their ineffectiveness in successful CPR, their use in conjunction with the potent vasodilator nitroglycerin has been evaluated in CA in porcine (Lurie et al 2002) and rat models of CA (Kono et al 2002b) in an effort to reduce the incidence of these adverse effects. Nitroglycerin is known to increase cardiac output, while, at the same time, it maintains CPP and mean blood flow in animal models of CA (Bache 1978, Brazzamono et al 1984, Colley & Sivarajan 1984, Zito et al 1985, Brazzamono et al 1988, Wenzel et al 1998 and in humans (Miller et al 1977, Groszmann et al 1982. In addition, the drug causes systemic vasodilation, especially in coronary blood vessels.…”

Symptomatic Reinfarction of a Previously Silent Myocardial Region Four Months After Successful Reperfusion

“…[1][2][3][4][5][6][7] Whether and to what extent intermittent episodes of myocardial ischemia and the presence of collateral vessels in such individuals protects them from myocardial infarction is uncertain. This case report describes a patient who developed an acute inferior wall myocardial infarction, hibernating myocardium, and extensive intercoronary collaterals who suffered acute myocardial reinfarction due to reocclusion 4 months after successful percutaneous transluminal coronary angioplasty (PTCA) of a totally obstructed, dominant right coronary artery.…”