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Results for “Coronary Occlusion”

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At least 19 recordsLinked to original sources
PubMed1990

Determinants of hemorrhagic infarcts. Histologic observations from experiments involving coronary occlusion, coronary reperfusion, and reocclusion.

Quantification of intramyocardial hemorrhage was performed in 69 pigs submitted to various protocols of coronary artery occlusion and reperfusion. The study groups include 1) permanent occlusion; 2) reperfusion after periods of coronary occlusion of 30, 45, 60, 90, and 120 minutes; 3) reperfusion with diltiazem and with 4) methoxamine after a 60-minute occlusion period; and 5) permanent reocclusion after a 30-minute period of reperfusion. Red blood cell counts were directly assessed by visual examination of histologic slices of myocardium and in a subgroup of animals by counts of red blood cells labeled with 99m-technetium pertechnetate. Hemorrhage occurs in infarcts reperfused after a duration of 45 minutes or more of coronary occlusion and after a period of reperfusion maintained for at least 30 minutes. Red blood cell counts were maximal in the mid portions of transmural sections of the infarcts, with decreasing values toward epicardium and endocardium. Diltiazem decreased total red blood cell counts, whereas methoxamine increased it and also caused subendocardial hemorrhage. The most powerful predictors of the severity of hemorrhage after sustained reperfusion were infarct size and higher blood pressure.

Animals↗
PubMed1986

ST segment response to acute coronary occlusion: coronary hemodynamic and angiographic determinants of direction of ST segment shift.

To assess the relationship between the direction of ST segment response to transient coronary occlusion and collateral function, we studied 25 patients with diagnostic ST segment changes during transient occlusion of the proximal left anterior descending artery (LAD). Electrocardiographic leads I, II, V2, and V5; left ventricular filling, aortic, and distal coronary pressures; and great cardiac vein flow were measured during percutaneous transluminal coronary angioplasty (PTCA) of the LAD. During a 1 min LAD balloon occlusion, 16 patients had reversible ST elevation (group I) and nine patients had ST depression (group II). The ST responses in individual patients were consistent during repeated occlusions, and ST depression never preceded ST elevation. Angiography before PTCA showed less severe LAD stenosis in group I (69 +/- 15%) than in group II (88 +/- 10%; p less than .01) and collateral filling of the LAD in no group I patient but in six of nine patients in group II (p less than .01). During LAD occlusion, determinants of myocardial oxygen demand (left ventricular filling pressure, aortic pressure, heart rate, and double product) were similar in both groups. Group I patients, however, had lower distal coronary pressure (25 +/- 8 vs 41 +/- 16 mm Hg) and residual great cardiac vein flow (33 +/- 14 vs 51 +/- 22 ml/min) and higher coronary collateral resistance (3.1 +/- 2.1 vs 1.5 +/- 0.8 mm Hg/ml/min) than group II patients (all p less than .05). In patients with ST elevation during LAD occlusion, stenosis before PTCA was less severe, visible collaterals were not present, and hemodynamic variables during LAD occlusion reflected poorer collateral function.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1986

Reactive dilation and late-hyperemic constriction of epicardial coronary artery after short coronary occlusion.

Coronary blood flow and epicardial coronary artery diameter were simultaneously measured by an electromagnetic or Doppler flow probe and a pair of ultrasonic crystals, respectively, during reactive hyperemia in conscious dogs. Reactive dilation appeared after the full appearance of reactive hyperemia and lasted for a period of 4-20 times the duration of the coronary occlusion. beta-Receptor blockade (propranolol, 1 mg/kg iv) attenuated both the reactive hyperemia in volume by 21-22% (P less than 0.01) and dilative responses of the epicardial coronary diameter by 27-28% (P less than 0.01), despite a nonsignificant attenuation of the resting or peak hyperemic coronary blood flow. When coronary blood flow was held constant during reperfusion, by an occluder distal to the ultrasonic crystals, the reactive dilation disappeared. A peculiar reactive constriction was noted when coronary occlusion was performed proximal to the site of the ultrasonic crystals. Appearance of this constriction was at 149 and 385 s after the release of 5 and 60 s of coronary occlusion, respectively. This late reactive constriction disappeared after pretreatment with alpha- (phentolamine, 1 mg/kg iv) and/or alpha- + beta-blockade, but not with beta-blockade alone, and it was not observed when the coronary diameter was measured proximal to the occluder. Thus reactive dilation of the epicardial coronary artery derives from an increase in coronary flow and is reduced by propranolol via a reduction in the hyperemic flow, suggesting a flow-dependent change in the diameter of the epicardial coronary artery. Reactive constriction is a local phenomenon following marked reduction in the coronary diameter and is abolished by alpha-adrenergic blockade with phentolamine.

Adrenergic alpha-Antagonists↗
PubMed1991

Continuous versus intermittent cardioplegia in the presence of a coronary occlusion.

Coronary artery occlusions can alter the distribution of cardioplegia and result in ischemic damage. This study was undertaken to determine whether continuous antegrade cardioplegia delivery would result in colder temperatures and provide better washout of acid metabolites than is possible with intermittent antegrade cardioplegia when coronary occlusions are present. Twenty pigs were placed on cardiopulmonary bypass and underwent 2 hours of ischemic arrest with occlusion of the middle left anterior descending coronary artery followed by 1 hour of reperfusion without occlusion of that artery. Ten pigs received intermittent (every 20 minutes) antegrade potassium crystalloid cardioplegia (4 degrees C), and 10 others had the same solution given continuously (30 mL/min). Cardioplegia distribution was assessed by continuous monitoring of myocardial pH (Khuri pH probe) and temperature in the region beyond the occlusion of the left anterior descending coronary artery. Both cardioplegic techniques resulted in tissue acidosis (continuous group, 6.69 +/- 0.08, versus intermittent group, 6.73 +/- 0.07; not significant). Average temperature in the left anterior descending coronary artery during arrest was also similar in both groups (continuous group, 18.3 degrees +/- 0.5 degrees C, versus intermittent group, 18.2 degrees +/- 0.5 degrees C). Because of these metabolic changes, both cardioplegic techniques resulted in abnormal wall motion in the anteroseptal region using two-dimensional echocardiography, but the scores were not significantly different (continuous group, 1.5 +/- 0.3, versus intermittent group, 1.6 +/- 0.4; 4 = normal to 0 = dyskinesia).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Responses of heart rate variability to coronary occlusion during coronary angioplasty.

Signs of sympathetic activation are frequent during the early hours of anterior wall acute myocardial infarction, whereas parasympathetic reflexes predominate in inferior wall acute myocardial infarction. To assess the immediate autonomic responses to acute coronary occlusion, the high-frequency power and root-mean-square successive difference, frequency and time domain measures of heart rate (HR) variability were analyzed in 73 cases of significant (50 to 95%) coronary artery stenosis immediately before and during balloon occlusion (mean 99 seconds). The range of nonspecific changes was formed on the basis of a control group with no ischemia during dilatations of 16 totally occluded coronary arteries. Balloon occlusion of the left anterior descending artery (n = 35) caused an abnormal increase in the measures of HR variability as a sign of vagal activation in 8 patients (23%), and a significant decrease in HR variability in 4 (11%). Occlusion of the left circumflex artery (n = 19) caused an increase in HR variability in 5 patients (26%), and a decrease in 2 (11%). Right coronary artery occlusion (n = 19) caused an increase in HR variability in 5 patients (26%) and a decrease in 4 (21%). Thus, coronary occlusion causes immediate changes in HR variability in greater than one third of patients with coronary artery disease. The direction of these initial HR variability changes cannot be predicted by the site of coronary occlusion.

Adult↗
PubMed1984

Effect of nitroglycerin on coronary collateral flow and pressure during acute coronary occlusion.

Coronary collateral function was evaluated in 21 conscious, unsedated patients by measuring aortic and distal coronary pressures and great cardiac vein flow during transient (1 minute) balloon occlusion of the anterior descending artery in the course of coronary angioplasty. Measurements were made before and during administration of intravenous nitroglycerin (NTG). Clinical, electrocardiographic and hemodynamic events of transient myocardial ischemia occurred in 10 patients before and 6 patients during NTG administration (p = 0.11). The NTG infusion consistently decreased pressure determinants of myocardial oxygen demand without increasing heart rate. NTG also decreased a calculated coronary collateral resistance index in 13 patients. Responsiveness to NTG did not appear to depend on the presence or absence of collateral vessels detected by angiography or on any other angiographic variable assessed. Measurement of coronary collateral function during coronary angioplasty is a new technique with the potential to assess the ability of interventions to prevent transient myocardial ischemia and improve myocardial perfusion during acute coronary occlusion in humans.

Adult↗
PubMed1988

[Effect of the beta-blocker propranolol (obzidan) on the content of macroergic phosphates and the development of the size of necrotic areas in the myocardium in experimental acute coronary occlusion].

Coronary arterial occlusion, maintained for 7 days in rabbits was accompanied by a marked and fairly stable drop in macroergic phosphates (ATP, creatine phosphate), seen in the perinecrotic and distant left and right ventricular myocardium. The administration of 0.5 mg/kg propranolol twice daily within 30-40 min after coronary arterial ligation resulted in a significant increase in ATP and the adenine nucleotides pool at a distance from the necrotic focus in the right and left ventricular myocardium on treatment days 3 and 7 and did not affect the recovery of normal creatine phosphate in the same myocardial areas. Propranolol treatment limited progressive death of myocardial cell population, reducing by 37% myocardial infarction size by day 7 of the experimental study, as compared to the situation in the untreated animals.

Acute Disease↗
PubMed1994

Incidence, predictors, and management of acute coronary occlusion after coronary angioplasty.

Acute coronary occlusion occurs in 4.3% to 8.3% of patients during coronary angioplasty. Its occurrence is difficult to predict in an individual patient. At high risk are patients with unstable angina, intracoronary thrombus, extreme age, long complex lesions, and diffuse disease. "Standard" management including redilation (prolonged perfusion) thrombolytic treatment and emergency bypass surgery is only successful in approximately 50% of the patients and is associated with a high mortality and myocardial infarction rate of < 6% and 30%, respectively. Bail-out stent implantation appears to emerge as an effective alternative in suitable patients and might reduce mortality, the apparent progression to myocardial infarction, or might decrease the need for emergency bypass. New techniques including directional atherectomy, rotational ablation, or the excimer laser are associated with a similar frequency of acute occlusion. Immediate access to a surgical back-up facility remains necessary to treat refractory acute occlusions.

Angioplasty, Balloon, Coronary↗
PubMed1982

Acute coronary occlusion during coronary angiography in two cases. Treatment by transluminal disobliteration.

Acute coronary obstruction occurred in two patients during coronary angiography. In one case the obstruction was in the left main coronary artery; in the other it was close to the origin of the left anterior descending artery. In both cases acute cardiac ischaemia ensued, with electromechanical dissociation and collapse, which was not reversible by resuscitation. Rapid disobliteration of the occluded coronary artery was done with a guide-wire pushed through the obstruction via the coronary catheter. The recanalisation was completed by an intracoronary perfusion of streptokinase in one case. In both cases recovery was rapid and spectacular. The occurrence of acute ischaemia during coronary angiography should suggest accidental coronary occlusion. If a thromboembolic origin is suspected, transluminal disobliteration should be attempted. It is simple and can reverse a dangerous condition.

Aged↗
PubMed1985

Complex coronary angioplasty in patients with prior coronary artery bypass surgery, in situations utilizing multiple coronary angioplasties, and in coronary occlusions.

Coronary artery bypass surgery not only provides symptomatic relief but also may prolong life in a significant percentage of patients. Repeat bypass surgery succeeds in providing symptomatic relief in a lesser number of patients, but it is associated with a higher morbidity and mortality than primary operations. Angioplasty, an interventional, therapeutic catheter technique, is applicable to a large number of patients who have undergone bypass surgery and who are sufficiently symptomatic to require consideration of another revascularization procedure. The gratifying results of successful lesion dilatation coupled with clinical improvement of the patient, the acceptable mortality and morbidity statistics, and the long-term symptomatic relief are comparable to those for repeat coronary bypass graft surgery. In addition, technologic advances in angioplasty equipment, as well as more knowledgeable interventionists, will enable more lesions to be successfully reached, traversed, and dilated with, it is hoped, a lower morbidity and mortality. We would estimate that 30 to 50 per cent of those patients requiring repeat revascularization operations today can undergo an angioplasty procedure with at least comparable clinical results and better morbidity and mortality statistics than those achieved with repeat bypass surgery. Selected patients underwent transluminal coronary angioplasty of varying combinations of arterial and/or vein graft stenoses. A multiple dilatation procedure was defined as successful when dilatation was achieved in all lesions in which it was attempted or when the considered-critical stenosis was dilated successfully and the patient was clinically improved. Angioplasty was successful in 93 per cent of all lesions in which it was attempted, and these successful dilatations produced a clinical improvement in 92 per cent of the patients. No complication whatsoever was experienced in 81 per cent of cases. The complications encountered included a 1.3 per cent mortality rate, a myocardial infarction rate of 6.9 per cent (3.0 per cent per lesion attempted), and an emergency surgery rate of 2.6 per cent (1.1 per cent per lesion attempted). Follow-up data show that a sustained clinical improvement was obtained in 96.8 per cent of the patients in whom the procedure was successful (with or without a repeat angioplasty). These data indicate that multiple coronary angioplasties can be performed during the same procedure, that clinical improvement can be achieved, and that the complication rate is acceptable.(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon↗
PubMed1984

Clinical and angiographic predictors of new total coronary occlusion in coronary artery disease: analysis of 313 nonoperated patients.

A new coronary artery occlusion was found in 98 of 313 consecutive patients (31%) with coronary artery disease treated medically who underwent catheterization twice, 39 +/- 25 months apart. Multivariate logistic regression displayed 8 independent predictors of new occlusion. Four were available at the time of the second angiogram: the interval between the 2 studies (p = 0.005), a decrease in ejection fraction (p less than 0.01), the appearance of bundle branch block (p less than 0.01), and an interim myocardial infarction (p less than 0.05). Four other predictors were found at the time of the first angiogram: 2 angiographic characteristics, 1 related to the severity (presence of an 80% or greater luminal diameter narrowing of an artery supplying a non-akinetic left ventricular segment [p less than 0.005]) and 1 to the extent (count of the lesions narrowed 75% or less in luminal diameter in a 15-segment coding system [p less than 0.05]) of coronary artery disease, and 2 risk factors: smoking status (p less than 0.05) and male sex (p less than 0.05). The 140 male smokers with at least 80% diameter stenosis or at least 4 segments with moderate (75% or less) stenosis were at a higher risk of occlusion than the 173 other patients after intervals of less than 2 years (13 of 53 vs 7 of 74, p less than 0.01), 2 to 4 years (23 of 40 vs 10 of 47, p less than 0.005) and more than 4 years (27 of 47 vs 18 of 54, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

In vivo inhibition of platelet aggregation and occlusive coronary thrombus formation by a new calcium antagonist (R023-6152).

Reports have shown that all three major classes of calcium antagonists can inhibit platelet aggregation in vitro. In this study, we compared the platelet antiaggregatory effects of R023-6152, a thiazepinone-type calcium antagonist, with diltiazem in an in vivo canine model of spontaneous coronary thrombosis. Plasma serotonin (5-HT) levels measured in the coronary sinus were used as an index of in vivo platelet aggregation and coronary flow measured by a Doppler flow probe. Untreated controls developed total coronary occlusion in 62 +/- 18 min after the current used to initiate thrombus formation was discontinued. Control 5-HT levels peaked at 213 +/- 63 ng/ml just before occlusion. Dogs receiving intravenous (i.v.) R023-6152 (200 micrograms/kg) or diltiazem (50 micrograms/kg) immediately after the current was discontinued exhibited no significant elevations in 5-HT values (12.3 +/- 1.4 and 1.84 +/- 0.42 ng/ml for R023-6152 and diltiazem, respectively) or development of coronary occlusions in the next 3 h. Small, transient decreases in arterial pressure (8-10 mm Hg) and changes in contractility occurred during infusion of both drugs. Gravimetric determinations of thrombus weights showed significantly smaller thrombi in the drug-treated animals as compared with controls. The results indicate that both R023-6152 and diltiazem are effective in suppressing in vivo platelet aggregation associated with occlusive coronary thrombus formation.

Animals↗
PubMed1975

Coronary occlusion during coronary angiography.

Between January 1, 1970, and December 31, 1974, 2981 patients underwent coronary arteriography. Twelve acute coronary dissections or embolizations occurred, an incidence of 0.4%. The incidences of acute occlusions for the Sones and Judkins techniques were 0.19% (4/2077 studies) and 0.88% (8/940), respectively. No instance of acute occlusion has occurred during the past 490 studies performed by the Judkins technique. Eight patients with right coronary artery dissections or circumflex emboli were treated medically. All survived, but in seven a myocardial infarction evolved. Four patients underwent emergency saphenous venous bypass grafting because of refractory ventricular fibrillation (two patients) or because large amounts of myocardium were thought jeopardized (two patients). All patients in this group had interruption of flow supplying the left anterior descending coronary artery. Despite surgical intervention in less than three hours in all patients, survivors all sustained transmural myocardial infarctions. Three patients survived surgery and were discharged home.

Acute Disease↗
PubMed1986

Guidewire snap causing left main coronary occlusion during coronary angioplasty.

The case of a 34-year-old female patient is presented. During attempted left anterior descending coronary angioplasty, the exchange guidewire (0.018 inch, 300 cm) snapped and the distal 20 cm of the wire caused immediate thrombotic occlusion of both the left anterior descending and circumflex arteries. The resulting complication was treated by emergency bypass surgery.

Adult↗