Spectrum of coronary arterial spasm. Clinical, angiographic and myocardial metabolic experience in 29 cases

Left ventricular end diastolic pressure for detection of intracoronary ergonovine-induced myocardial ischemia

BACKGROUND

Recent consensus on variant angina defines significant spasm as total or subtotal occlusion of a coronary artery. However, the clinical significance of "less-than-subtotal" spasm needs to be reappraised, especially if the coronary spasm is combined with chest pain. Therefore, we evaluated the feasibility of left ventricular end diastolic pressure (LVEDP) as a tool to detect myocardial ischemia during ergonovine provocation testing.

METHODS

After achieving two access sites, 29 patients underwent successful LVEDP monitoring using 5-Fr pigtail catheters during ergonovine provocation tests. Patients were divided into two groups based on the occurrence of anginal symptoms.

RESULTS

Of the 29 patients, 16 (55 %) patients had anginal symptoms. LVEDP was significantly increased in the symptomatic group compared with the nonsymptomatic group (∆LVEDP 5.6 ± 4.2 vs. 1.2 ± 2.0 mmHg, p = 0.002). However, of the 16 patients with anginal symptoms, positive provocation test results were confirmed in only six patients (38 %) as per the traditional standard (> 90 % inducible spasm of the epicardial coronary artery).

CONCLUSION

Compared with the traditional standard, LVEDP may have advantages in terms of elucidating anginal symptoms in patients suspected of having coronary vasospasm when performing ergonovine provocation tests.

Long-term clinical and angiographic follow-up in patients with isolated ostial stenosis of the left coronary artery

BACKGROUND

Isolated ostial stenosis (IOS) of the left coronary artery is a rare disease of unknown etiology, and the long-term prognosis and angiographic characteristics of affected patients have not been fully studied.

METHODS AND RESULTS

The present study investigated 57 patients with stenosis of the left main trunk (LMT) who underwent coronary artery bypass grafting (CABG). They were categorized into 3 groups, based on the angiographic findings: Group I comprised 9 patients with IOS; Group II comprised 12 patients with left coronary ostial stenosis in the presence of distal vessel obstructions; Group III comprised 36 patients with stenosis of LMT excluding ostial stenosis and associated with distal vessel obstruction. The patients underwent serial angiography at 1, 5, and 10 years after CABG. Middle aged women with fewer coronary risk factors were more common in Group I compared with Groups II and III (P<0.01). The patency rate of the internal thoracic artery grafts was significantly higher in Groups II and III than in Group I (P<0.05). In Group I, the percentage stenosis of LMT lesions decreased significantly (P<0.05), but there was no difference in the other groups.

CONCLUSIONS

IOS had clinical characteristics and time course distinct from those of atherosclerotic LMT disease.

Failure of Serial Electrocardiograms to Exclude a Large Anterior Myocardial Infarction and the Role of Transesophageal Echocardiogram in Acute Myocardial Infarction

When patients present with acute onset of chest pain suggestive of myocardial ischemia, immediate clinical decisions regarding thrombolysis, percutaneous transluminal coronary angioplasty, or both are usually based on the history and abnormal electrocardiograms and confirmed by the presence of abnormally elevated cardiac enzymes. However, there are potential limitations of the electrocardiograms and initial cardiac enzymes in the diagnosis and confirmation of acute myocardial infarction. We describe the case of a patient who presented with an acute onset of chest pain and had a normal electrocardiogram and initial cardiac enzymes yet was found by transesophageal echocardiography to have a large myocardial infarction.

Vagally mediated multivessel coronary artery spasm during coronary angiography

We report on a case of multivessel coronary artery spasm preceded by vagal signs and symptoms, which resolved after administration of atropine. This supports that the spasm was triggered by endogenous acetylcholine.

Effects of thoracic epidural anesthesia on changes in ischemic myocardial metabolism induced by intracoronary injection of endothelin in dogs

OBJECTIVE

Thoracic epidural anesthesia (TEA) has been reported to alleviate ischemic damage to the myocardium. Endothelin, an endothelium-derived peptide and a potent coronary vasoconstrictor, may contribute to poor cardiac perfusion and ischemia. The objective was to examine regional myocardial metabolism during ischemia caused by intracoronary injection of endothelin with and without TEA.

DESIGN

The three experimental groups and three treatments were randomized.

SETTING

All studies were conducted in a university research laboratory.

PARTICIPANTS

Thirty anesthetized dogs comprised the study groups.

INTERVENTIONS

Study animals were divided into three groups of 10 animals each identified as normal saline (NS); TEA; and TEA + blood pressure controlled (TEA + BPC). The NS group had 0.5 mL/kg of normal saline injected into the T4-5 epidural space. The TEA group had 0.5 mL/kg of saline containing 1% lidocaine injected into the T4-5 space. The TEA + BPC group had blood pressure and heart rate maintained at pre-epidural injection values by partially occluding the descending aorta and by atrial pacing. Endothelin (15 pmol/kg) was bolus injected into the left anterior descending (LAD) artery of each heart. Systolic and diastolic blood pressure, heart rate, and LAD coronary blood flow (CBF) were monitored. Three minutes after injection of endothelin, myocardial tissue was sampled from the distribution of the LAD artery and from the control, left circumflex (LCx) artery. ATP, ADP, AMP, lactate, and pyruvate were measured by enzymatic methods.

MEASUREMENTS AND MAIN RESULTS

It was found that in each group endothelin consistently decreased LAD CBF, but the decrease was less in the TEA + BPC group. In the tissue distribution of the LAD, the levels of ATP and energy charge potential were lower, and the level of lactate was higher in the NS group than in the TEA or the TEA + BPC groups (p < 0.01).

CONCLUSIONS

These results confirm that (1) endothelin injected into the LAD artery decreases CBF and causes selective myocardial ischemia in a fashion similar to intravascular stenosis of the LAD rather than to mechanical occlusion and (2) TEA, with or without pressure support, lessens the degree of regional ischemia induced by injection of endothelin in the LAD.

Nonatherosclerotic causes of coronary artery narrowing--Part II

Part II of this three-part article on nonatherosclerotic causes of coronary heart disease focuses on myocardial bridges, coronary artery aneurysms, emboli, coronary dissection, and spasm as causes of luminal narrowing.

Instability of ST segments in the early stages of acute myocardial infarction in patients undergoing continuous 12-lead ECG monitoring

Many patients presenting to the emergency department with suspected acute myocardial infarction (AMI) have an initial 12-lead electrocardiogram (ECG) nondiagnostic for acute injury and thus do not meet any accepted ECG criteria for thrombolytic therapy. Early studies in the use of intracoronary thrombolytic therapy documented that cyclic variations in ST segment magnitudes between normalcy and injury are common during the early phase of AMI and correspond to spontaneous intermittent coronary opening and reocclusion. The reliance on a single ECG to diagnose AMI may mean that many patients with AMI are missed if the initial ECG is obtained during a window of ST segment normalcy. We present 3 patients with AMI who underwent continuous 12-lead ST segment monitoring with frequent serial ECGs whose ST segments periodically normalized during the acute injury phase. We believe continuous 12-lead ST segment monitoring with frequent serial ECGs can aid the physician in identifying patients with AMI who may benefit from thrombolytic therapy and other urgent revascularization techniques.

ST-segment instability preceding simultaneous cardiac arrest and AMI in a patient undergoing continuous 12-lead ECG monitoring

Little data exist concerning the actual onset time (time zero) in sudden death (SD) and acute myocardial infarction (AMI). Most studies have focused on describing the warning arrhythmias that occur before SD and AMI and have relied on retrospective analyses of fortuitous data obtained from patients who experience these adverse outcomes while undergoing routine ambulatory holter monitoring. Because of the limitations of holter monitoring, little information is known concerning the actual incidence of ST-segment changes preceding SD and AMI. The first case of simultaneous onset of silent SD and AMI occurring in a patient undergoing continuous 12-lead electrocardiograph (ECG) monitoring during his initial emergency department evaluation is reported. Analyses of the serial 12-lead electrocardiographs showed extensive transient silent ST-segment elevations and depressions preceding cardiac arrest and AMI and provided insight in the pathogenesis of SD and AMI. Continuous 12-lead ECG monitoring can identify patients at high risk for SD and AMI and allow physicians to intervene before the development of life-threatening conditions.

Oxidized low density lipoproteins cause contraction and inhibit endothelium-dependent relaxation in the pig coronary artery

The direct vasoactive effects of native and oxidatively modified low density lipoproteins as well as their effects on endothelium-dependent relaxations to 5-hydroxytryptamine were studied in isolated rings of pig right coronary artery. Slowly developing contractions were caused by native low density lipoproteins (100 micrograms protein/ml). The contractions were more pronounced in the absence than in the presence of the trace metal chelator, EDTA, and coincided with the formation of lipid peroxides during the response. The lipophilic antioxidant, butylated hydroxytoluene, prevented the oxidation of, and contraction to, native low density lipoproteins. Low density lipoproteins oxidized by exposure to copper contracted coronary arteries more rapidly with a threshold of only 1 micrograms protein/ml, but with a similar maximal contraction at 100 micrograms protein/ml. Superoxide dismutase inhibited the contraction to native low density lipoproteins, but not to oxidized low density lipoproteins. Catalase blocked contractions to both native and oxidized low density lipoproteins. Contractions to oxidized low density lipoproteins were unaffected by indomethacin, but were abolished by removal of the endothelium or by inhibitors of endothelium-derived relaxing factor. Oxidized low density lipoproteins but not native low density lipoproteins inhibited endothelium-dependent relaxations to 5-hydroxytryptamine. Thus, oxidized low density lipoproteins caused endothelium-dependent coronary artery contractions which are mediated by a hydroperoxide. Contractions to native low density lipoproteins are due to their oxidation in the organ chamber by the superoxide anion radical. Oxidized, but not native, low density lipoproteins impair normal endothelial cell vasodilator function in vitro. Oxidized low density lipoproteins, important in the pathogenesis of atherosclerosis, may directly contribute to the increased risk of vasospasm seen in hypercholesterolemia and atherosclerosis.

Significance of coronary artery tone in patients with vasospastic angina

To investigate the relation between basal coronary artery diameter and development of coronary artery spasm, the diameters of the proximal, middle and distal segments of the three major coronary artery branches, together with that of the left main trunk, were measured on a control angiogram and after ergonovine and nitrate administration in 30 patients with vasospastic angina without significant organic stenosis, and in 35 patients without ischemic heart disease. The percent change in coronary diameter after ergonovine and nitrate administration compared with the control diameter was used as an index of coronary vasoreactivity. In patients with vasospastic angina, coronary artery responses to both ergonovine and nitrate were greater in the spastic segments than in the other segments (p less than 0.05), and those of the coronary arteries without spasm were greater than those of the coronary arteries in patients without ischemic heart disease (p less than 0.01). There were no significant differences between the coronary artery diameters in the two groups after nitrate administration, and the control diameters were less in patients with vasospastic angina than in patients without ischemic heart disease. These observations indicate that a coronary vasomotion disorder, which involves increased basal coronary artery tone and hypersensitivity to vasoconstrictive stimuli, not only at a localized segment but also in the entire coronary artery tree, is present in patients with vasospastic angina. Clinically, evaluation of basal coronary artery tone may be useful for predicting the occurrence and location of coronary artery spasm.

Augmented vasoconstrictor responses to serotonin precede development of atherosclerosis in aorta of WHHL rabbit

Watanabe heritable hyperlipidemic (WHHL) rabbits have elevated concentrations of plasma cholesterol and develop progressive atherosclerosis. The present investigation was undertaken to evaluate the vascular responses to vasoactive compounds of aorta from WHHL rabbits and normal New Zealand White (NZW) rabbits at 1 and 6 months of age. Rings of distal thoracic aorta were suspended under isometric tension in oxygenated Krebs buffer. Developed tension was measured in response to graded concentrations of agonists. Maximal responses to KCl (40 mM) were the same in aortas from the 1-month-old and 6-month-old WHHL and NZW rabbits. Aortas from 1-month-old animals were more sensitive to serotonin than aortas from 6-month-old animals. Aortas from WHHL rabbits exhibited an increased maximal response to serotonin when compared with NZW controls. In contrast, the constrictor responses to norepinephrine were reduced in WHHL rabbits compared with NZW rabbits at both age groups. Methacholine decreased tension development in serotonin-contracted vessels. This relaxation was greatest in aortas from NZW rabbits. In 1-month-old NZW rabbits fed a high cholesterol diet, the constrictor responses to serotonin and the relaxation responses to methacholine did not differ from NZW rabbits ingesting a normal diet. However, the responses to norepinephrine were markedly attenuated in the hypercholesterolemic NZW rabbits. Microscopic evaluation of the aortas revealed occasional adherent leukocytes and irregularities in the vascular endothelium in 1-month-old WHHL animals. These changes were greater in aortas from 6-month-old WHHL animals, with more adherent leukocytes, adherent platelets, and severe irregularities in the endothelial surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelets and antiplatelet therapy in ischemic heart disease

Blood platelets have been shown to play an important role not only in thrombosis, but also in the pathogenesis of coronary artery disease and its complications. Drugs that affect platelets have been shown to reduce mortality in survivors of acute myocardial infarction, to reduce the risk of myocardial infarction in patients with unstable angina, and to preserve the potency of saphenous venous grafts used to bypass obstructed coronary arteries. The drugs may also play a role in the primary prevention of arteriosclerosis and in preventing thrombotic complications following coronary angioplasty.

Supersensitivity of coronary arteries in variant angina to spasm induced by intracoronary acetylcholine

Acetylcholine (20 to 100 micrograms) was infused directly into coronary arteries in 10 patients with variant angina (group A), 13 subjects without coronary artery disease (group B) and 8 patients with significant organic coronary artery stenosis (greater than or equal to 50%) but without variant angina (group C) during coronary arteriography, to clarify the action of this agent on coronary arteries. Temporary pacing was performed at a demand heart rate of 40 beats/min while bradyarrhythmia developed. Coronary arteriography after administration of acetylcholine showed coronary vasoconstriction in all 10 patients (100%) of group A. Angina accompanied by electrocardiographic ischemic changes in 9 of 10 (90%, 7 ST-segment elevation and 2 depression) was provoked during this test. In the patients of group B, acetylcholine also induced vasoconstriction in 8 of 22 (36%) coronary arterial systems examined, chest pain in 3 (14%) and ST-segment deviation in none (0%). In the patients of group C, acetylcholine induced vasoconstriction in 3 of 9 (33%), chest pain in 2 (22%) and ST-segment depression in 1 (11%). No definite coronary artery dilation induced by acetylcholine was noted. Coronary vasoconstriction (p less than 0.05), electrocardiographic ischemic findings (p less than 0.01) and chest pain (p less than 0.01) were induced significantly more frequently in group A than in both groups B and group C. No significant difference was found between group B and group C. The coronary arteries in the patients with variant angina seem to be more susceptible to acetylcholine than those of patients without variant angina irrespective of the presence of significant atherosclerosis.

Increased subendothelial infiltration of the coronary arteries with monocytes/macrophages in patients with unstable angina. Histological data on 14 autopsied patients

We report semi-quantitative histological data on coronary arteries, collected at autopsy from Japanese of both sexes (Group I) who had had unstable anginal attacks and transient ST elevation or depression in ECG within 1 month before death. The cause of death in all cases was acute myocardial infarction or coronary sudden death. A control group consisted of 28 autopsied patients (Group II) who had died of causes other than heart disease and who had been free from anginal attacks. The frequency of 51-75% and 76-100% luminal narrowing in the coronary arteries in Group I was statistically higher than that in Group II (P less than 0.01). Subendothelial infiltration of monocytes/macrophages with edematous change was most evident in Group I in all segments of the coronary artery, particularly in the proximal portions of the three main branches, regardless of mural or occlusive thrombotic sites of the coronary artery. The subendothelial infiltration of monocytes/macrophages, in terms of luminal narrowing, was the most frequent in the portions with 0-50% luminal narrowing, followed by portions with 51-75% narrowing. The subendothelial infiltration of mononuclear cells with edematous change, observed mostly in the proximal portions of three main branches of the coronary artery in Group I, was attributed to increased subendothelial permeability and endothelial damage caused by coronary vasospasm of recent occurrence. We propose that repeated vasospasm may lead to further progression of coronary atherosclerosis.

Simultaneous multivessel coronary artery spasm demonstrated by quantitative analysis of thallium-201 single photon emission computed tomography

Thallium-201 myocardial scintigraphy with quantitative analysis of emission computed tomography was performed during episodes of angina in 19 patients with variant angina and nearly normal coronary arteriographic findings. Eleven patients (group I) were shown by arteriography to have spasm in 2 or more large coronary arteries. Eight patients (group II) had spasm in only 1 coronary artery. In 7 patients in group I, significant diffuse perfusion defects simultaneously appeared in multiple coronary artery regions on the scintigram (group IA). The extent and severity of the perfusion defect as measured by thallium-201 tomography were significantly greater in group IA than in group II (p less than 0.001 and p less than 0.01, respectively). The duration of transient ST-segment elevation during the attack in group IA was significantly longer than in group II (p less than 0.001). The incidence of ventricular arrhythmias, including ventricular tachycardia, or complete atrioventricular block during the anginal attack was significantly higher (p less than 0.05) in group IA than in group II. In all study patients, neither attack nor scintigraphic perfusion defect appeared on the repeat test after oral administration of nifedipine. In conclusion, multivessel coronary artery spasm simultaneously appears and causes the attack in many patients with variant angina and nearly normal coronary arteriographic findings, and myocardial ischemia due to simultaneous multivessel coronary spasm is likely to be more extensive and severe, persist longer and have a higher frequency of potentially dangerous arrhythmias than that due to spasm of only 1 coronary artery.

Diffuse triple-vessel coronary artery spasm complicated by idioventricular rhythm and syncope

A 70-year-old man presented with diffuse triple-vessel coronary arterial spasm accompanied by ST segment elevation in the inferior and anterior leads when the severity of pain moderated. At the beginning, he noted throat and chest pain followed by syncope. Atropine, norepinephrine, and lidocaine were administered therapeutically. The initial electrocardiogram showed an idioventricular rhythm without ST segment deviations, which made the prompt diagnosis of coronary arterial spasm difficult.

Haemodynamics during repeated exercise tests with special reference to the 'warm-up' phenomenon in patients with angina pectoris

The haemodynamic effect of two successive supine exercise tests 20 min apart was examined in 12 patients with angina pectoris. All the patients had coronary artery disease verified by angiography and were accepted for coronary bypass surgery. They exercised 20-40 W and all of them had angina during the first exercise test. Half the patients did not experience angina during the second of the two exercise tests ('warm-up' responders). In these patients left ventricular filling pressure (LVFP) was reduced by 40% (P less than 0.01) in the second compared to the first exercise test. The non-responders showed no significant change in LVFP. The heart rate pressure product (RPP) and thus myocardial oxygen demand were unchanged in responders and non-responders. In another 10 patients with angina and coronary artery disease, also accepted for coronary bypass surgery, atropine (1.5-2.0 mg) was given intravenously. Ten minutes after administration of atropine, these patients followed exactly the same investigation programme including two successive supine exercise tests as in the group not given atropine. In the group given atropine, four 'warm-up' responders and six non-responders showed the same pattern of response in LVFP as in the group not given atropine. In the 'warm-up' responders a smaller increase in RPP was observed during the second exercise test compared to the first. The present study indicates that cholinergic mechanisms are probably not involved in the 'warm-up' phenomenon. Due to the difference in haemodynamic response, the 'warm-up' phenomenon has to be taken into account when evaluating results from haemodynamic studies of cardiovascular drugs.

Usefulness of ST deviation induced by prolonged hyperventilation as a predictor of cardiac death in angina pectoris

One hundred ninety patients with chronic angina for an average of 2 years were followed. Forty-seven had at least 1 mm of ST deviation in response to provocation of coronary vasoconstriction by prolonged hyperventilation (group I); 143 had no ST deviation (group II). The angiographic response to this test was studied in 21 patients from group I, and revealed 25 to 100% diameter reduction; in group II 9 patients showed a 5 to 14% diameter reduction. In group I, 15 patients (32%) died (hazard rate = 0.17 deaths/patients X years) vs 18 (13%) in group II (hazard rate = 0.06) (p less than 0.01). Seven patients in group I (15%) and 3 in group 2 (2%) died while waiting for surgery (p less than 0.01). All patients who died had coronary stenoses of at least 70%. A Cox regression analysis, using 24 variables (invasive and noninvasive), showed a positive hyperventilation test (ST deviation at least 1 mm), low ejection fraction and systolic blood pressure of at least 160 mm Hg to be independent predictors of death (p less than 0.05). Considering only deaths in non-operated patients (patients waiting for surgery and patients not planned to undergo operation), a rate-pressure product/100 of 150 or less at exercise stress testing, left ventricular end-diastolic pressure of 15 mm Hg or more and duration of angina less than 1 year were also independent predictors of death. Thus, the hyperventilation test may be useful for identifying angina patients who are at high risk of cardiac death due to dynamic coronary obstructions.

Dynamic variations in resistance of coronary arterial narrowings in angina pectoris at rest

The coronary hemodynamic events in 4 patients with frequent episodes of spontaneous rest angina were investigated. The basal coronary transstenotic pressure gradients showed more severe stenosis than that seen on coronary arteriography, suggesting that angiography in this setting may underestimate the true extent of coronary atherosclerosis. Episodes of angina were triggered by marked, sudden increases in the transstenotic coronary pressure gradient and a decrease in coronary blood flow without alterations in systemic arterial pressure or heart rate. These changes in coronary hemodynamics were promptly reversed by the intracoronary administration of nitroglycerin. No such spontaneous variations in transstenotic coronary pressure gradients were observed in 37 patients with a history of classic exertional angina but no rest angina. These unique data represent direct hemodynamic evidence that an increase in resistance at the site of a coronary stenosis, most likely the result of an increase in arterial tone, can be a cause of transient myocardial ischemia in patients with angina at rest.

Human leucocyte antigen in variant angina

Human leucocyte antigen analysis of 45 patients with variant angina was performed to determine the presence of causative genetic factor(s). A significantly low frequency of human leucocyte antigen DQ omega 3 was found in these patients, as compared with that in 152 normal Japanese adults. There were no differences in frequencies of antigens between patients with normal and those with atherosclerotic coronaries. These data suggest that some genetic factor(s) may contribute to the pathogenesis of coronary spasm.

Unstable angina pectoris: the first half century: natural history, pathophysiology, and treatment

Unstable angina pectoris as a distinct syndrome intermediate between chronic stable angina and acute myocardial infarction was first described about a half century ago. The incidence of death or myocardial infarction rises in the first few months after destabilization of angina. Hemodynamic, scintigraphic, and arteriographic studies in the last 15 years have shown that unstable angina is chiefly due to "dynamic" coronary stenoses, transient reversible limitations in coronary blood flow caused by a complex interaction between coronary vasoconstriction, transient platelet plugging, and transient thrombosis. The trigger for the onset of dynamic coronary stenoses is probably acute changes in coronary arterial morphology in or near atherosclerotic plaques making those areas more thrombogenic. A large fraction of patients with unstable angina restabilize initially with medical management. The role of beta blockers is unclear, but they may protect against development of coronary events for patients with unstable angina similar to that reported for patients with myocardial infarction. Nitrates and calcium blockers are probably superior to beta blockers in restabilization of angina, but protection against coronary events has not yet been demonstrated clearly. Further investigation is needed to distinguish the relative benefits of a two-drug (heart rate-limiting calcium blocker plus nitrates) regimen vs. a three-drug regimen including beta blocker. There is no basis for emergency coronary bypass surgery to prevent myocardial infarction or death. Urgent surgery should be limited to patients who do not stabilize readily with medical therapy. One third or more of the patients who initially restabilize with medical therapy will require coronary revascularization in the year after unstable angina because of severe angina. An antithrombotic regimen of aspirin (or possibly heparin) reduces the incidence of progression to death or myocardial infarction. Two important future directions for research should be promising: development of better antithrombotic regimens other than aspirin alone for protection against coronary events; and improved ability to distinguish the patients who initially respond to medical therapy who are at low risk for later severe angina from those at higher risk.

Provocation of coronary spasm by dopamine in patients with active variant angina pectoris

The effects of dopamine on arteries are different depending on the dose, route of administration, and receptor population. Its administration can cause vasodilation by stimulation of dopaminergic receptors, vasoconstriction by stimulation of alpha-adrenergic and serotonergic receptors, and even spasm of cerebral arteries when given intracisternally in dogs. The ability of dopamine to provoke coronary spasm was assessed in 18 patients with active vasospastic angina in whom this amine was infused at rates of 5, 10, and 15 micrograms/kg/min for periods of 5 min each. The 12-lead electrocardiogram and blood pressure (cuff) were monitored throughout the whole test. In nine patients dopamine caused angina and ischemic electrocardiographic changes suggestive of coronary spasm: ST segment elevation in six patients and ST segment depression in the absence of important coronary stenoses in the remaining three. Infusion of dopamine was repeated during coronary angiography in three patients with positive test results: this provoked occlusive coronary spasm with ST segment elevation in two patients and nonocclusive spasm with ST segment depression in the remainder. In conclusion, infusion of dopamine provokes coronary spasm in a sizeable proportion of patients with active vasospastic angina. Its administration may be detrimental in patients susceptible to coronary spasm, such as those with acute myocardial infarction.

Clinical and angiographic findings in angina at rest

The purpose of this study was to delineate the clinical, ECG, and angiographic features of a large series of consecutive patients with angina at rest. Transient ST segment elevation during pain was observed in 219 patients (group I), while 220 patients showed ST segment depression during pain (group II). Group II patients were found to have higher incidence of hypertension (p less than 0.001), prior myocardial infarction (p less than 0.0005), history of exertional angina (p less than 0.0005), and a progressive aggravation of symptoms before hospitalization (p less than 0.0005), while group I patients had a prevalence of recent onset angina (p less than 0.05) and more frequently developed severe ventricular arrhythmias during pain (p less than 0.0005). Furthermore, a larger number of patients showing ST segment depression during chest pain had multivessel disease (p less than 0.0005), left main involvement (p less than 0.005), and lower values of left ventricular ejection fraction (p less than 0.001) than patients with ST segment elevation during pain. Survival curves of medically treated patients showed a significantly better long-term prognosis in patients of group I (p less than 0.01). The direction of the ST segment shift during anginal attacks at rest may therefore allow a classification of patients included into the broad spectrum of unstable angina. This distinction should be taken into consideration in studies aimed at evaluating long-term prognosis or the results of medical and surgical therapy.

Coronary artery spasm induced in miniature swine: angiographic evidence and relation to coronary atherosclerosis

In a swine model of coronary artery spasm, the pathogenetic role of coronary atherosclerosis was examined. Following endothelial balloon denudation of the left circumflex coronary artery (LCX), male miniature swine were fed a laboratory chow diet containing 2% cholesterol. Although there was no difference in the extent of coronary vasoconstrictive response to histamine, serotonin, and ergonovine between the left anterior descending coronary artery (LAD) and the LCX before the denudation, a constrictive response was significantly augmented along the denuded portion of the LCX 1 and 3 months after the denudation. Augmented vasoconstrictive responses to phenylephrine were never evidenced. Histamine was the most potent vasoactive agent, and coronary artery spasm was provoked repeatedly by intracoronary or intravenous administration of histamine in the presence or absence of cimetidine. The spasm was provoked only in the denuded portion of the LCX, the same area which was angiographically normal before the occurrence of the spasm. Histologically, atherosclerotic changes were predominant along the denuded portion of the LCX. Topologic correlation was suggested between the site of the spasm and the site of coronary atherosclerosis. It is concluded that in this swine model of coronary artery spasm, atherosclerotic changes may be an important causative factor, in terms of an activation of multiple receptor-operated calcium channels in the coronary artery.

Ventricular ectopic activity with spontaneous variant angina: frequency and relation to transient ST segment deviation

This study was performed (1) to assess the frequency of ventricular ectopic activity (ventricular bigeminy, couplets, or ventricular tachycardia) during spontaneous variant angina; (2) to assess the relation between ventricular ectopy and the severity and duration of ischemia; and (3) to evaluate the precise temporal relation between episodes of ischemia and ventricular ectopy. Fifteen ambulatory patients with variant angina (12 men, 3 women, aged 50 +/- 8 [mean +/- SD] years) had Holter monitoring for 24 hours/week for 10 months (total, 10,238 hours of monitoring), from which the following were measured during each episode of ST deviation (elevation or depression): duration of ST deviation (minutes), maximal ST deviation (millivolts), presence of ventricular ectopic activity, and timing of ventricular ectopy in relation to ST deviation. Of 645 episodes of ST deviation, 79 (12.2%) had associated ectopy, almost all of which occurred in three patients. The 79 episodes of ST deviation with ectopy lasted 4.6 +/- 3.3 minutes and averaged 0.16 +/- 0.12 mV, whereas the 566 episodes of ST deviation without ectopy lasted 4.7 +/- 6.1 minutes and averaged 0.17 +/- 0.11 mV (NS in comparison to the 79 episodes with ectopy). Of 489 episodes of ST elevation, 72 (14.7%) were accompanied by ventricular ectopy; of 156 episodes of ST depression, only seven (4.5%) had ectopy (chi 2 = 11.531, p less than 0.001). Of the 79 episodes of ventricular ectopy, almost all appeared during a period of increasing or maximal ST deviation, whereas only two appeared as ST deviation was resolving.(ABSTRACT TRUNCATED AT 250 WORDS)

Patients with malignant or potentially malignant ventricular arrhythmias: opportunities and limitations of drug therapy in prevention of sudden death

Almost 90% of patients resuscitated from out of hospital cardiac arrest have coronary heart disease and can be categorized in one of three groups: acute myocardial infarction, ischemic event or primary arrhythmic event. The patients who have acute myocardial infarction have the best prognosis, and those with primary arrhythmic events have the worst. Recent studies show that ventricular arrhythmias after myocardial infarction are associated with mortality independent of any association with left ventricular dysfunction. Ventricular arrhythmias that have caused cardiac arrest or hemodynamic collapse, that is, malignant arrhythmias, should be treated aggressively and evaluated carefully with one of two methods that have high predictive accuracy for outcome: 1) the Holter recording/exercise test approach, or 2) the electrophysiologic approach. It is not yet known whether treating potentially malignant ventricular arrhythmias after myocardial infarction with class I or III antiarrhythmic drugs will reduce mortality, but two clinical trials are under way in the United States to address this question. Beta-adrenergic blocking drugs do reduce mortality, probably as a result of both antiischemic and antiarrhythmic effects. Calcium channel blocking agents, various antiplatelet drugs and alpha-adrenergic blocking drugs are under investigation to determine their value in secondary prevention of ventricular fibrillation.

Significance of adventitial inflammation of the coronary artery in patients with unstable angina: results at autopsy

A quantitative analysis of adventitial inflammation of the coronary artery with intimal lesions is described in 12 patients who suffered coronary death and had had unstable angina (crescendo angina) at rest (group 1). After autopsy in these patients we examined epon-embedded cross sections by light and electron microscopy, paying particular attention to the adventitia, and compared these results with those in six patients who had had angina but died of noncardiac causes (group 2) and those in 22 patients who did not have angina (group 3). Of the 132 segments from group 1 patients, 39 (30%) were narrowed 76% to 100% by atherosclerotic plaque (group 2, 27%; group 3, 1%), and 23 (17%) had occlusive thrombi. Of the 264 sections (two from each segment) from group 1 that were examined, 98 (37%) (group 2, 15%; group 3, 9%) revealed clustered infiltration of inflammatory cells in the adventitia, half of which were associated with vascular nerve involvement. These findings in the adventitia may be related to the vasospastic component of unstable angina.

Issues in the natural history and treatment of coronary heart disease in black populations: medical management

Data from multiple sources indicate that the death rate for blacks is higher than for the general population-in part because of higher mortality from cardiovascular causes. The Cardiovascular Mortality Survey, carried out in Los Angeles, indicates that the combined effects of increased mortality from high blood pressure and related causes (e.g. stroke, cerebrovascular disease), together with an ischemic heart disease mortality rate that is only a little below the mean, accounts for the overall excess mortality rates in blacks. In addition, black patients have been shown to have higher risk profiles compared with the study mean in a large study of beta-blocker therapy, and a definite treatment effect was demonstrated. Further prospective studies of natural history and response to therapy are indicated for appropriately selected patient groups.

Isolated perfused rabbit coronary artery and aortic strip preparations: the role of endothelium-derived relaxant factor

Isolated perfused coronary arteries and aortic ring preparations of rabbits were studied, both with intact endothelium and with endothelium removed by K-rich solution and friction respectively. Constrictor dose-responses to histamine, acetylcholine, phenylephrine and 5-hydroxytryptamine (5-HT) were measured. They were greatly depressed by the presence of endothelium in coronary preparations. In aortic preparations endothelium affected dose-responses relatively little, depressing the response to acetylcholine but apparently increasing the responses to the other three agents. Acetylcholine relaxed pre-constricted coronary or aortic preparations but only when endothelium was present. This relaxation was inhibited by quinacrine or hydroquinone. Aortic preparations had resting tone which could be increased by hydroquinone if endothelium was present, suggesting continual release of endothelium-derived relaxant factor (EDRF) at rest. When allowance was made for basal EDRF activity in aortic preparations, the maximal constrictor response to acetylcholine remained lower in the presence of endothelium, consistent with acetylcholine stimulation of EDRF, but maximal constrictor responses to the other three agents were the same with and without endothelium, suggesting that the direct constrictor response overrides EDRF activity.

Reduced myocardial blood flow resulting from dynamic changes in coronary artery stenosis

To evaluate the interaction of coronary vasomotor tone and stenosis, we studied the effects of ergonovine and adenosine on partially obstructed coronary arteries in 6 closed chest dogs. Coronary stenosis was created by partially inflating a balloon catheter with a distal lumen in the left anterior descending or circumflex coronary artery. Stenotic resistance was calculated as the mean pressure gradient across the stenosis divided by the mean blood flow measured with 15 micron radioactive microspheres. Coronary artery vasoconstriction, induced by ergonovine (0.6 mg i.v.), caused a small, but nonsignificant, increase in stenotic resistance (1.42 +/- 0.25 to 2.68 +/- 0.64 mm Hg/ml per min) and had no effect on myocardial blood flow. Coronary arteriolar dilation induced by adenosine increased stenotic resistance (1.52 +/- 0.25 to 9.01 +/- 2.49 mm Hg/ml per min, P less than 0.05) and the pressure gradient across the stenosis (18.8 +/- 3.0 to 41.3 +/- 7.5 mm Hg, P less than 0.05). Adenosine increased myocardial blood flow from 0.52 +/- 0.05 ml/min per g to 1.43 +/- 0.20 ml/min per g (P less than 0.05) in the regions supplied by unstenosed arteries, while in the region perfused by the stenosed artery blood flow fell from 0.51 +/- 0.06 to 0.29 +/- 0.13 ml/min per g (P less than 0.05), with the endocardium most severely affected (0.55 +/- 0.04 ml/min per g to 0.26 +/- 0.09 ml/min per g, P less than 0.05). Thus changes in severity of stenosis produced by altered coronary pressure and flow can influence blood flow to the myocardium. Such dynamic changes in coronary artery stenosis may be important in the pathogenesis of angina and myocardial infarction.

Coronary artery spasm induced in atherosclerotic miniature swine

Angiographically demonstrable coronary artery spasm could be provoked repeatedly by giving intracoronary or intravenous injections of histamine to miniature swine with experimentally induced atherosclerotic lesions of the coronary artery. The spasm induced in this way subsided either spontaneously or after the administration of nitroglycerin and was prevented by a calcium antagonist or an agent that blocks histamine H1 receptors. This model, which suggests that atherosclerotic changes may be one of the primary factors in the occurrence of coronary artery spasm, should facilitate studies on the pathogenesis of this condition.

Factors influencing the long-term prognosis of treated patients with variant angina

To determine the prognosis of variant angina and the factors influencing it, 169 consecutive patients hospitalized in our coronary unit were followed for a mean of 15.3 months (range 1 to 68). Survival at 1, 2, and 3 years was 95%, 90%, and 87%, respectively; survival without myocardial infarction was 80%, 78%, and 75%. Twenty of the 22 myocardial infarctions and eight of the 14 deaths occurred within the first 3 months. Mantel-Haenszel log-rank analysis demonstrated that coronary disease, ventricular function, and the degree of disease activity were significant interdependent variables that influenced both survival and survival without infarction. At 1, 2, and 3 years, survival for patients with multivessel disease was 81%, 76%, and 66%; for patients with one-vessel disease, 97%, 92%, and 92%; and for patients without stenoses greater than or equal to 70%, 98% at each year (p = .0003). Survival without infarction at 1 year was 88% in patients with no stenoses greater than or equal to 70% and 82% in patients with single-vessel disease; it did not change thereafter in either group, but was 62%, 58%, and 50% at 1, 2, and 3 years in patients with multivessel disease (p = .001). Treatment did not influence survival in any subgroup (only 14 patients died overall) or survival without infarction in patients with multivessel disease. However, in patients without multivessel disease, treatment with nifedipine, diltiazem, and verapamil improved survival without infarction compared to treatment with perhexiline maleate or long-acting nitrates alone (92% vs 67% at 1, 2, and 3 years; p less than .005). Thus in addition to preventing angina, nifedipine, diltiazem, and verapamil appear to reduce complications in patients with variant angina without multivessel disease.

Natural history of pure coronary artery spasm in patients treated medically

The clinical course of 59 patients with coronary artery spasm and no fixed severe coronary obstruction was analyzed for an average of 5.9 years. The study group consisted of 27 men and 32 women. Angina at rest was the predominant symptom in 93% of the patients. Myocardial infarction occurred in 19% and syncope during angina in 27%. During spontaneous anginal episodes, 64% of the patients showed ST segment elevation, 17% ST segment depression and 15% no electrocardiographic changes. Major arrhythmias during angina occurred in 24% of the patients. Permanent pacemakers were required in 10% of the patients. Stress tests were positive in 32% of the patients. Long-acting nitrate therapy controlled symptoms in only 31%, and calcium antagonist agents controlled symptoms in 83% of the patients unresponsive to nitrates. Spontaneous remission of angina for at least 1 month while receiving no medical treatment occurred in 39% of the patients. Fifteen percent of patients had an indefinite remission with no recurrence of symptoms for at least 2 years. There were no cardiac deaths. The natural history of medically treated patients with pure coronary spasm is characterized by recurrent angina at rest, frequent spontaneous remission, a poor response to long-acting nitrate therapy and a good response to calcium antagonists. Although myocardial infarction and major arrhythmias are common, cardiac mortality is low in medically treated patients.

Effects of vasoconstriction and distal dilation on carotid stenoses in the dog

Traditionally, arterial stenoses have been assumed to be inflexible, static obstructive lesions that could not acutely change their configuration or cross-sectional area. However, recent clinical and experimental observations have shown that coronary arterial stenoses can respond to vasoconstriction and intraluminal pressure changes. This experimental study evaluated whether similar dynamic changes could occur in a carotid artery stenosis. The effects of dilation distal to a circumferential snare were examined in 6 mongrel dogs. To eliminate collateral flow, the distal carotid artery was occluded and blood flow diverted through a 16 or 20 gauge needle. With no stenosis, distal dilation increased flow from 29.0 +/- 2.0 to 90.1 +/- 3.8 ml/min, (p less than 0.01). With moderate stenosis, the flow increase (25.5 +/- 1.3 to 56.4 +/- 3.7 ml/min, p less than 0.01 following dilation was attenuated. With severe stenosis, flow paradoxically decreased (20.4 +/- 1.0 to 11.4 +/- 1.0 ml/min, (p less than 0.01). This flow decrease was associated with a large stenotic resistance increase (2.13 +/- 0.51 to 18.93 +/- 5.58 mm Hg/ml . min-1, (p less than 0.01). In eight additional experiments, an in vitro preparation was used to examine the effects of vasoconstriction on stenotic severity. Vasoconstriction, induced by ergonovine, methoxamine, angiotensin, or vasopressin, resulted in a significant flow decrease and stenotic resistance increase. Thus, both vasoconstriction and intraluminal pressure were shown to affect stenotic severity, and thereby influence blood flow. These data illustrate hemodynamic factors which may be important in patients with severe carotid artery stenosis.