Effect of nitroglycerin on regional myocardial blood flow following an experimental coronary spasm

This study was designed to evaluate the effect of nitroglycerin (30 micrograms given as an i.v. bolus) on regional distribution of myocardial blood flow in conscious dogs, following an acute coronary occlusion similar to a coronary spasm. The left anterior descending (LAD) coronary artery was acutely occluded with a balloon cuff occluder. The distribution of blood flow between the endocardium and the epicardium of both the normal and ischemic area of the left ventricle was determined by means of the radioactive microsphere technique. Acute occlusion of the left anterior descending coronary artery produced a significant decrease of blood flow reaching the area irrigated by this artery; this decrease was of a lesser magnitude after administration of nitroglycerin. In addition, ischemia produced a disproportionate decrease in endocardial blood flow. This decrement was also of a lesser magnitude following administration of nitroglycerin. Blood perfusion to the non-ischemic myocardium was not altered. These results indicate that an intravenous bolus of nitroglycerin, given after a brief coronary occlusion simulating a coronary spasm, increases blood flow to the ischemic myocardium, induces a favorable redistribution of blood flow toward the ischemic endocardium and does not produce any decrement of blood perfusion to the non-ischemic myocardium.     

Multivessel coronary artery spasm.

A 60-year-old patient with variant angina was shown to have myocardial ischemia in two different regions supplied by separate major coronary arteries. Neither artery had significant coronary atherosclerotic obstruction. Ventricular fibrillation was noted during ST-segment elevation in anteroseptal leads. The attacks of pain and arrhythmias disappeared during nifedipine therapy.     

Stenting for coronary artery spasm.

We evaluated coronary stenting in nine patients with clinically severe, angiographically documented spasm refractory to aggressive pharmacologic management. No patient subsequently developed unstable ischemia requiring hospitalization as a consequence of recurrent spasm within the stent. Mechanisms of therapeutic failure included both persistent spasm and spasm in a different artery in one patient. Restenosis occurred in three patients who subsequently underwent repeat revascularization. In the rare, carefully selected patient, stents may represent an adjunct in the management of focal coronary artery spasm, although currently medical therapy remains the standard initial approach.     

Reduction of coronary blood flow during coronary artery spasm occurring spontaneously and after provocation by ergonovine maleate

A 50-year-old man suffering from recurrent chest pain accompanied by transient ST-segment elevation developed spasm of the left anterior descending coronary artery after receiving ergonovine maleate. During spontaneous chest pain, thermodilution coronary sinus blood flow fell from 96 ml/min to 46 ml/min, while the coronary sinsu arteriovenous oxygen difference widened from 9.82 volumes percent to 11.3 volumes percent. During spontaneous relief of pain, coincident with resolution of the ST-segment changes, coronary sinus blood flow gradually rose to 135 ml/min, while coronary sinus arteriovenous oxygen difference narrowed to 6.82 volumes percent. Similar aterations in coronoary sinus blood flow accompanied chest pain provoked by ergonovine maleate. A thallium-201 scan confirmed a perfusion defect in the distribution the left anterior descending coronary artery. Thus, coronary artery spasm can produce a marked deficity in coronary blood flow that is associated with increased myocardial oxygen extraction; release of spasm creates a hyperemic response.     

Angiographic abnormalities associated with alterations in regional myocardial blood flow in coronary artery disease.

To evaluate the association between alterations in myocardial blood flow and angiographic findings, myocardial blood flow was compared in 26 patients with asymergy, 15 patients with a similar extent of coronary artery disease but without asynergy, and 10 patients without coronary artery disease or obvious myocardial or valvular disease. Myocardial blood flow was measured at rest with an Anger camera and PDP-11/20 computer after the intracoronary injection of 133xenon. In comparison with the normal subjects, whole heart blood flow was significantly reduced in patients with asynergy. In addition, myocardial blood flow in regions of anteroapical asynergy was reduced (85-7 +/- 7-0 ml/min per 100 g3 in controls to 65-4 +/- 4-5, P less than 0-05) and a similar reduction was noted in regions of posterolateral asymergy (91-5 +/- 8-8 in controls to 66-8 +/- 5-0, P less than 0-05). In general, regional myocardial blood flow was reduced distal to left anterior descending or left circumflex stenosis of less than 50 per cent, with a trend toward further reduction distal to less than 75 per cent stenosis. In these same patients, the presence of anteroapical or posterolateral asynergy resulted in a similar trend to even greater reduction of flow. The effect of collaterals was variable: 7 of 8 patients without asynergy but with less than 75 per cent left anterior descending stenosis and collateral circulation to the lower left anterior descending quadrant had minimally reduced flows. However, in the 17 patients with anteroapical asynergy, regional myocardial blood flow was very similar in the 9 patients with collaterals compared with the 8 patients without them. This study suggests that the degree of coronary artery stenosis and presence of asynergy are both important in evaluating alterations in myocardial blood flow in coronary artery disease, while the role of collaterals remains uncertain.     

Refractory coronary artery spasm

A patient with an episode of refractory myocardial ischemia induced by ergonovine is described. The patient underwent cardiac catheterization 2 weeks after an inferior wall myocardial infarction for evaluation of recurrent rest angina. He developed severe spasm of the proximal right coronary artery in response to ergonovine which was partially relieved with nitrates and calcium channel antagonists. However, myocardial ischemia persisted, culminating in a new inferior wall infarction. The possible mechanism of continuing intense ischemia despite partial relief of the proximal right coronary spasm is discussed. It is suggested that ergonovine testing should perhaps be avoided during the early postinfarction period. Furthermore, if an ergonovine test is anticipated, beta-adrenergic blocking agents should be withheld.     

Multivessel coronary artery spasm

Coronary spasm is increasingly recognised as an important aetiological mechanism causing myocardial ischaemia. Occasionally cases present with evidence of ST segment elevation myocardial infarction, usually secondary to spasm confined to a solitary coronary artery. We present the rare and life-threatening case of severe coronary spasm afflicting all three major epicardial arteries simultaneously. It describes the difficult emergency scenario and ongoing management dilemmas encountered by physicians confronted with multivessel coronary spasm. Moreover we discuss the malignant prognosis associated with this ailment and describe the potential insights provided by cardiac magnetic resonance imaging that might identify those at greatest risk after the index event.     

Exercise-induced coronary spasm with S-T segment depression and normal coronary arteriography

The unique association of both exercise-induced coronary arterial spasm and S-T segment depression with normal findings on selective coronary arterlography is described. The patient had a prior history of typical effort angina that had recently progressed to angina at rest. Despite the change In anginal pattern, the electrocardiogram disclosed S-T segment depression that was consistent with subendocardial Ischemia, during both exercise testing and spontaneous chest pain. Exercise thallium-201 sclntigraphy demonstrated the presence of large perfusion defects of the anterior and septal walls of the left ventricle. Coronary arteriographie findings, in the absence of symptoms, were entirely normal. Severe localized, reversible coronary spasm of the proximal left anterior descending coronary artery was subsequently demonstrated during spontaneous angina, Isometric arm exercise and after the administration of ergonovine maleate. After treatment with isosorblde dlnitrate and nifediplne, the patient had no further chest pain or electrocardiographic changes, and a repeated thallium-201 stress test revealed nomal findings and greatly Improved exercise tolerance.