Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0151814 (coronary occlusion)
 3,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

These effects of dipyridamole, carbochromen, pentaerythritol tetranitrate (PETN), papaverine and ethaverine on collateral hemodynamics were investigated in anesthetized dogs 5 weeks after experimental coronary occlusion. The retrograde pressure, flow and resistance (RP, RF and RR) and the pressure, flow and resistance of the nonoccluded artery (CP, CF and CR) were measured; the pressure, flow and resistance ratios, i.e., the circulatory relationships which appeared between areas localized on both sides of the well-developed collateral channels, were calculated. Dipyridamole and carbochromen provoked an inappropriate and long-lasting redistribution to the detriment of ischemic areas: RF and RP decreased, whereas CF increased; RP/CP and RF/CF decreased; RR/CR increased. PETN provoked a redistribution in favor of ischemic areas: RF increased and RR decreased; RP/CP and RF/CF increased; RR/CR decreased. These main effects of PETN appeared after a first short period during which the changes in normal and ischemic areas were almost identical. Like PETN, papaverine and ethaverine provoked an appropriate redistribution during a second period. These results are discussed in terms of the selectivity of coronary dilator action on large or small vessels. The methodology used appears to be adequate to evaluate the activities of various drugs on a well-developed collateral coronary circulation.
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PMID:Effects of some coronary vasodilator drugs on collateral hemodynamics after chronic myocardial ischemia in the anesthetized dog: appropriate or inappropriate redistribution? 63 70

To study the regional function of nonischemic myocardium after the onset of regional ischemia, graded circumflex coronary arterial stenosis was induced in 18 open-chest anesthetized dogs. Two-dimensional echocardiographic views were obtained at each degree of occlusion in a cross-sectional plane marked by two to three metal beads sewn to the left ventricular epicardium. Percent systolic thickening was measured at 16 equally spaced points around the left ventricle and correlated with microsphere-determined regional myocardial blood flow. Baseline thickening averaged 44.9 +/- 6.4%. During transmural ischemia percent systolic thickening decreased to -16.1 +/- 4.0% in the ischemic region and also decreased in adjacent nonischemic regions (to 2.4 +/- 2.4% in segments closest to the ischemic region [adjacent 1] and to 15.5 +/- 3.9 in segments further away [adjacent 2]), but was unchanged in segments directly opposite the ischemic region (remote region). During subendocardial ischemia, percent systolic thickening fell only in the ischemic and adjacent 1 regions (1.4 +/- 5.2% and 24.9 +/- 5.0%, respectively). Dipyridamole, 0.21 to 0.42 mg/min iv, given to seven dogs during transmural ischemia, caused a three- to fivefold increase in flow to the nonischemic and no change in flow to the ischemic region; function was not altered in any region. Propranolol, 0.1 mg/kg iv, was given to five dogs during transmural ischemia to depress contractility in the remote region. Percent systolic thickening fell in the remote (from 50.0 +/- 7.7% to 34.6 +/- 5.6%), but increased in adjacent 1 (from -0.25 +/- 3.7% to 15.2 +/- 3.9%) and in adjacent 2 (from 17.4 +/- 2.8% to 33.4 +/- 3.9%) regions, and remained unchanged in the ischemic region. We conclude the following: During transmural ischemia percent systolic thickening is markedly impaired in nonischemic myocardium immediately adjacent to the ischemic region, and is impaired to a lesser degree in regions located relatively far from the ischemic border. Dysfunction therefore overestimates the extent of regional ischemia after total coronary occlusion. During subendocardial ischemia function ceases in the ischemic region and functional impairment of nonischemic myocardium is restricted to immediately adjacent regions. Dysfunction of adjacent regions is not caused by "relative ischemia" related to increased local oxygen demands or to a steal phenomenon. Mechanical tethering of nonischemic myocardium adjacent to ischemic regions, secondary to changes in left ventricular shape during contraction, may contribute to the impairment of systolic thickening in adjacent regions during transmural ischemia.
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PMID:Impaired thickening of nonischemic myocardium during acute regional ischemia in the dog. 398 75

Ligature of the anterior interventricular coronary artery in the dog is a model that is used, classically, to study antiarrhythmic properties of drugs. It can also be used to demonstrate arrhythmogenicity. In this study, twenty hours after coronary ligature, cardiac arrhythmia was reduced by oral administration of quinidine and phenytoin. This effect lasted over several days after the coronary occlusion. By Day 2, more than 60% of the treated dogs had a predominantly sinus heart rhythm, compared with 20% of the controls. This antiarrhythmic treatment also seemed to reduce mortality. Dipyridamole was subsequently injected i.v. at 0.5 and 1 mg/kg on Days 2, 3, and 4 after coronary ligature. On Day 2, dipyridamole significantly increased the proportion of ectopic beats and significantly lowered the proportion of sinus beats. This drug can thus worsen arrhythmia induced by coronary occlusion. On Days 3 and 4, dipyridamole showed no arrhythmogenic effects, but there was a significant increase in sinus automaticity.
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PMID:Use of experimental myocardial infarct to demonstrate arrhythmogenic activity of drugs. 399 57

The effects of 3 different doses (0.02, 0.1, 0.5 mg/kg/h) of dipyridamole on myocardial infarct size were evaluated in pentobarbital anesthetized open-chest dogs following sequential coronary occlusion of two medium sized coronary arteries in the same heart. The first coronary occlusion produced a control infarct, the other a test infarct under the influence of the drug. Dipyridamole infusion was started 10 min before the second occlusion at a rate of 0.02 (group A, n = 9), 0.1 (group B, n = 10) or 0.5 (group C, n = 9) mg/kg/h respectively and continued to the end of reperfusion (90 min). Biopsy samples were obtained at the end of each occlusion period and at the end of the second reflow period. Infarct size was determined using post mortem angiography and pNBT staining. Control and treated infarct sizes, expressed as a percentage of the perfusion area, were 21.9 +/- 5.4% vs. 25.2 +/- 7.7% in group A (n = 9), 21.8 +/- 7.3% vs. 18.3 +/- 5.2% in group B (n = 9), and 22.3 +/- 7.7% vs. 16.2 +/- 4.8% in group C (n = 8). There were no significant differences between control and treated infarct sizes in the 3 groups. After 90 min coronary occlusion tissue adenosine contents in the ischemic myocardium were significantly higher (42 +/- 7 nmol/gww in group C and 40 +/- 5 nmol/gww in group B) than those in the nonischemic myocardium, and dipyridamole enhanced these levels (395 +/- 6 nmol/gww in group C: p less than 0.01, 55 +/- 10 nmol/gww in group B). Dipyridamole did not affect the tissue inosine levels in the ischemic myocardium after 90 min coronary occlusion. ATP and creatine phosphate levels were not affected by dipyridamole during ischemia or during reflow. The accumulated adenosine was not phosphorylated to AMP and on to ATP upon reperfusion.
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PMID:Influence of dipyridamole on infarct size and on cardiac nucleoside content following coronary occlusion in the dog. 409 85

Changes in segmental forces of contraction (determined by a strain gauge arch) in non-ischemic (normal) and ischemic regions of the same left ventricular wall were studied in dogs anesthetized with morphine and pentobarbital. A branch of the left anterior descending coronary artery was completely occluded, and 10 min after occlusion coronary dilators were injected intravenously. The results can be summarized as follows. 1) Coronary occlusion markedly reduced the segmental force of contraction in the ischemic region, while it did not affect that in the normal region. Heart rate did not change markedly after coronary occlusion. 2) Either nitroglycerin (100 microgram/kg) or sodium nitrite (2.5 mg/kg) increased heart rate, and it also increased segmental force of contraction in the normal region while it decreased that in the ischemic region. 3) Papaverine (1 mg/kg) increased heart rate and segmental forces of contraction in both normal and ischemic regions. 4) Dipyridamole (250 microgram/kg) slightly increased heart rate, and it also increased segmental force of contraction in the normal region but not in the ischemic region.
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PMID:Effects of coronary dilators on segmental forces in normal and ischemic regions of the canine left ventricular wall. 677 30

Effects of antagonists on the ST alternans during acute coronary occlusion were examined in dogs. The intravenous administration of verapamil at doses of 0.1 mg/Kg and 0.2 mg/Kg prominently attenuated the degree of alternans. Diltiazem at dose of 0.2 mg/Kg also attenuated the degree of alternans. Dipyridamole at dose of 0.5 mg/Kg did not significantly attenuate the degree of alternans. Verapamil significantly inhibited the ST-segment elevation. After verapamil, ST alternans did not occur even after a longer period of occlusion when changes in QRS complex and the ST-segment elevation were remarkable. It is possible that verapamil inhibits ST alternans by both the protecting effect against ischemic injury and a direct effect on the electrical activity of the myocardial cell membrane.
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PMID:Effect of calcium antagonists on the electrical alternans of the ST segment during acute coronary occlusion in dogs. 723 May 24

1 The effects of Ca2+ -antagonists on the relationships between alternate changes in the ST-T complex in the epicardial electrogram, ST-T alternans, and associated excitation-conduction abnormalities during coronary occlusion were examined in anaesthetized dogs. 2 Epicardial unipolar electrograms, bipolar electrograms (BPEG) and monophasic action potentials (MAP) were recorded with unipolar, composite and suction electrodes, respectively. 3 ST-T alternans was associated with serious conduction delay. During the period of ST-T alternans, the amplitude of MAP changed alternately and the negative deflection of the ST-T complex was associated with a larger MAP. A depression of the TQ level and decrease in the resting potential of MAP were marked. 4 Verapamil (0.2 mg/kg) and diltiazem (0.5 mg/kg) inhibited ST-T alternans, conduction abnormalities, TQ depression and changes in MAP. However, after these drugs, the TQ depression and the decrease in the resting potential were evident after a longer period of occlusion at a time when ST-T alternans, conduction abnormalities and alternate changes in MAP were still inhibited. Dipyridamole (0.5 mg/kg) had no effect on either ST-T alternans or the conduction abnormalities. 5 Verapamil and diltiazem inhibited ST-T alternans and the associated excitation and conduction abnormalities. The effects of these two drugs cannot be explained on the basis of attenuation of the decrease in the resting potential.
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PMID:Effects of calcium antagonists on the alternation of the ST-T complex and associated conduction abnormalities during coronary occlusion in dogs. 731 86

Patients with a chronic coronary occlusion often undergo coronary angiography after weeks to months of occlusion. The published reports underestimate the extent of this problem because such patients are often arbitrarily assigned to receive medical therapy or undergo bypass surgery as a result of poor success with percutaneous revascularization and substantial restenosis. Thus, there is controversy about the role of angioplasty in this patient cohort. The goal of this overview was to evaluate the available information about angioplasty in chronic coronary occlusions. The primary indication for attempted recanalization of a chronic coronary occlusion has been symptomatic angina pectoris. Anginal status often improves after successful procedures (70% vs. 31% with a failed procedure); left ventricular function may improve; and subsequent referral for coronary artery bypass graft surgery is uncommon (3% vs. 28% in unsuccessful cases). Successful recanalization is achieved in approximately 65% of attempted procedures. Inability to cross the stenosis with a guide wire is the most common cause of procedural failure. Statistically significant predictors of procedural success include older occlusions (75% < 3 months old vs. 37% > or = 3 months old), absence of any anterograde flow through the occlusion (76% with vs. 58% without), angiographically abrupt-appearing occlusions (50% vs. 77% with tapered occlusions), presence of bridging collateral vessels (23% with vs. 71% without) and lesions > 15 mm. Procedural complications occur at a slightly lower incidence than in angioplasty of high grade subtotal stenoses. Long-term success is limited, and restenosis can be expected in > 50% of the patients. The experience with chronic total occlusions of saphenous vein bypass grafts is small, but there appear to be limited procedural success and significant procedural complications, particularly associated with distal emboli. The role of new pharmacologic agents has yet to be defined and that of new devices has been disappointing so far, but further technologic advances are on the horizon.
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PMID:Percutaneous revascularization of chronic coronary occlusions: an overview. 779 37

Twenty-five dogs were exposed to gradual coronary occlusion by placing Ameroid constrictors around the origins of the left circumflex and anterior descending coronary arteries. Previous experiments have demonstrated that these constrictors absorb water and, over a period of three weeks, narrow the cross-sectional area of the two arteries to 50% or less, and consequently cause the death of 80% of the experimental animals. Twelve of the 25 animals were fed 50 mg. of Persantin three times a day by mouth commencing one day before the operative procedure. Determinations of the concentration of the drug in the blood revealed a level consistent with that obtained in humans after the administration of therapeutic doses. Eleven of the 13 control animals died in the three-month experimental period while only six of the 12 treated animals expired. Injections of Schlesinger mass in all animals dying or killed following the experimental period demonstrated that Persantin significantly accelerated the development of intercoronary anastomoses in the treated group, and in the surviving animals produced a rich anastomotic network much in excess of that seen in the surviving animals in the control series that were exposed to hypoxia alone. On the basis of these experimental findings, it is suggested that Persantin may favourably alter the prognosis of many patients with coronary artery disease.
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PMID:The effect of persantin on intercoronary collateral circulation and survival during gradual experimental coronary occlusion. A preliminary report. 1392 1

Effects of coronary vasodilator, dipyridamole, on epicardial oxygenation and flow were investigated under conditions of moderate coronary occlusion using near-infrared spectroscopic (NIRS) and thermal imaging. In anesthetized open chest pigs an inflatable occluder and flow probe were placed around the left anterior descending artery (LAD). In the ischemic group (n = 11) LAD occlusion (50% flow, 80 min) was followed by complete occlusion (10 min, n = 4), and reflow. Dipyridamole was infused (0.14 mg/min/kg/4 min) intravenously during 50% occlusion. In the control group (n = 6) LAD flow was temporarily increased (hyperemic response) by two 2-min periods of complete LAD occlusion applied 120 min apart, with a 4-min period of dipyridamole infusion between the two occlusions. NIRS and thermal images were acquired throughout the protocol. Maps of subepicardial oxygen saturation parameter (OSP), and epicardial temperature (T) were obtained. Partial occlusion reduced OSP and the temperature by 0.23 +/- 0.08 and 0.88 +/- 0.39 degrees C versus remote region, respectively. Dipyridamole decreased systolic blood pressure by 36%, which caused further decline in the LAD flow to 18% and OSP and T by 0.37 +/- 0.01 and 2.46 +/- 0.32 degrees C, respectively. Reflow restored OSP and T to their baseline levels. In control group dipyridamole and hyperemia increased LAD flow 2-4-fold associated with moderate increase in OSP and T. OSP and T showed linear dependence on the flow below 100%, which is leveled-off at flows above normal. Dipyridamole increases differences in the epicardial oxygenation and T between normal and moderately ischemic areas due to enhancement of disparity in perfusion of these areas.
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PMID:Detection of moderate regional ischemia in pig hearts in vivo by near-infrared and thermal imaging: effects of dipyridamole. 1743 19


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