Coronary artery spasm: prevalence, clinical significance, and provocative testing

Recent clinical and laboratory observations indicate that coronary artery spasm may play a role in the pathophysiology of ischemic heart disease. The majority of patients with ischemic heart disease have coronary atherosclerosis. The prevalence of coronary artery spasm in these patients is unknown. However, current evidence suggests that patients with rest angina have a higher incidence of coronary artery spasm than do patients with reproducible effort angina. Coronary artery spasm may initiate or contribute to acute myocardial infarction, but recent evidence obtained in patients undergoing thrombolytic therapy during the early phases of myocardial infarction suggests that it is not a common occurrence. Although numerous examples of ventricular tachycardia and ventricular fibrillation occur during episodes of coronary artery spasm, the incidence of coronary artery spasm in association with sudden death is unknown. Provocative testing with ergonovine maleate reveals that the highest incidence of provocable coronary artery spasm is found in patients with rest angina. In patients with the syndrome of variant angina, coronary artery spasm is nearly always provocable.

Regional coronary hemodynamic responses to cold stimulation in patients without variant angina

The responses to cold in patients with exertional chest pain were studied by measuring coronary sinus and great cardiac vein flows, aortic and left ventricular pressure and diameters of epicardial and small (0.4 to 1.0 mm) intramyocardial coronary arteries before and after the left hand of 18 such patients was immersed in ice water. Coronary sinus and great cardiac vein flows were used as indexes of total and anterior left ventricular flows. Coronary sinus flow minus great cardiac vein flow was used as an index of inferior left ventricular flow. Perfusion of left ventricular regions was considered potentially "normal" or "abnormal" according to the presence or absence of 50 percent or greater stenosis of luminal diameter in the coronary artery supplying a given region. With cold stimulation, increases occurred in heart rate (6 beats/min), mean aortic pressure (22 mm Hg) and left ventricular end-diastolic pressure (8 mm Hg) (all p less than 0.05). Left ventricular flow in normally perfused regions increased as resistance decreased. Left ventricular flow in abnormally perfused regions increased slightly and resistance increased. Regional left ventricular flow increased more, and changes in resistance differed in normally and abnormally perfused regions. Coronary arterial diameter decreased only minimally (6 percent) in both normal and abnormal left ventricular regions. These data show that cold stimulation increases coronary resistance in abnormally perfused left ventricular regions. Cold stimulation-related increases in coronary resistance do not appear to be caused by coronary arterial "spasm."

Short- and long-term responses to diltiazem in patients with variant angina

Short- and long-term effects of diltiazem on angina frequency were studied in 12 patients with variant angina (pain at rest with S-T elevation). Each patient first entered a double-blind short-term trial. Either diltiazem, in two dosage schedules (120 and 240 mg/day), or placebo was administered in a randomized double-blind program over 10 weeks. Significant decreases in frequency of angina were observed when diltiazem treatment periods were compared with placebo periods. Six patients were asymptomatic, one had 50 percent or greater decrease, and two had a smaller decrease in angina frequency. Two patients showed no important improvement during short-term diltiazem therapy. One patient experienced ventricular fibrillation in the placebo period and was advanced to treatment with open label diltiazem before responses could be ascertained in the double-blind trial. All other patients were then advanced to open label diltiazem therapy and followed up for an average of 16 months (range 8 to 23). Responses during the short-term trial accurately predicted responses during long-term therapy. Of the six patients who were asymptomatic during short-term therapy, five remained asymptomatic and one had rare episodes of angina. One other patient continued to have a good response (50 percent or greater decrease in angina frequency) and two other patients had a partial response. The two patients who did not respond during short-term therapy did not respond during long-term therapy.

Action of intracoronary nitroglycerin in refractory coronary artery spasm

Coronary artery spasm usually responds to sublingual nitroglycerin. This report describes four patients with variant angina and one patient with rest angina who had coronary spasm that was refractory to sublingual or i.v. nitroglycerin. In four patients, spasm occurred spontaneous and in one patient after 0.05 mg of ergonovine. In each case, 25-100 micrograms of intracoronary nitroglycerin promptly (30-45 seconds) resulted in reopacification of the vessel involved in spasm and resolution of evidence for ischemia. Thus, intracoronary nitroglycerin can reverse coronary artery spasm that does not respond to systemic nitroglycerin administration.

Randomized double-blind comparison of nifedipine and isosorbide dinitrate in patients with coronary arterial spasm

The effects of nifedinpine and isosorbide dinitrate on the frequency of angina and consumption of nitroglycerin were studied in 19 patients with coronary arterial spasm. After a lead-in phase, the patients were randomized to treatment with either nifedipine or isosorbide dinitrate. After dose titration (40 to 120 mg/day) and evaluation, they were given the alternate therapy. During the initial segment of the double-blind phase, one patient died suddenly (nifedipine phase), one dropped out of the study (nifedipine phase) and another was unable to tolerate therapy (isosorbide dinitrate phase). In the other 16 patients, the mean frequency of angina was less during therapy with both nifedipine (0.69 episode/day, p less than 0.05) and isosorbide dinitrate (0.77 episode/day, p less than 0.05) phases than during the lead-in phase (1.71 episodes/day). The mean frequency of angina was similar in the nifedipine and isosorbide dinitrate phases. A 50 percent or greater decrease in frequency of angina compared with lead-in phase values occurred in 13 of 18 patients during treatment with nifedipine and in 10 of 16 during treatment with isosorbide dinitrate. Of the 16 patients who completed both double-blind phases, 7 showed greater improvement (that is, a 50 percent or greater decrease in frequency of angina) with nifedipine than with isosorbide dinitrate); 6 others showed greater improvement with isosorbide dinitrate, and the other 3 had a less than 50 percent difference in frequency of angina with the two drugs. These findings in a limited number of patients suggest that both nifedipine and isosorbide dinitrate are effective in certain patients with coronary spasm but that neither drug is clearly superior.

Variability of electrocardiographic responses to repeated ergonovine provocation in variant angina patients with coronary artery spasm

We reviewed our experience with serial ergonovine provocative tests for coronary artery spasm (CAS) in ten variant angina patients with angiographically proved CAS. Of the 26 ergonovine tests performed in the ten patients, only four patients exhibited reproducible ECG response to ergonovine. The remaining six patients had variable and unpredictable ECG responses to ergonovine. All patients were in an active phase of their disease. The variability of ST segment directional response to ergonovine is considered to be on the basis of disparate sensitivity of the coronary circulation to intravenous ergonovine. Because of this variable response, the ECG response alone should not be considered as the standard indicator for CAS presence but should be utilized with other hemodynamic and angiographic criteria.

Effects of selective injection of contrast media on coronary artery diameter

The purpose of this study was to quantify the effect of Renografin-76 on epicardial coronary artery diameters, during selective coronary angiography. Using 105 mm-photospot angiograms taken at 0, 1, and 5 min, 99 coronary segments from ten patients were measured. Comparing the angiograms at 1 and 5 min to the control angiograms, a 7 +/- 7% and 6 +/- 7% (both p = NS) change in diameter respectively was noted. Comparing the 1 and 5 min angiograms, there was no significant change (-1 +/- 7%). Measurements were found to be very reproducible. This study shows that there is a trend toward dilation of the coronary arteries during selective coronary angiography, but this did not reach statistical significance and probably is not clinically important.

Short-term efficacy of oral verapamil in rest angina. A double-blind placebo controlled trial in CCU patients

To determine the efficacy and safety of oral verapamil in patients with rest angina admitted to the Coronary Care Unit (CCU), a double-blind placebo-controlled trial was undertaken. Of the 65 patients with rest angina screened for the study, 15 met the inclusion criteria (at least two episodes of chest pain associated with ST-T segment changes per 24 hours) during single-blind placebo phase (Day 1). Patients were then randomized to receive either placebo or verapamil (80 mg every 6 hours) on Day 2. Protocol was designed such that those who did not respond to the placebo (nonresponders) received verapamil, 80 mg every 6 hours, whereas verapamil nonresponders received increased doses (120 mg every 6 hours) on Day 3. Those who did respond (responders) continued to receive their medication. Similar action was taken on Day 4, depending on chest pain frequency and clinical evaluation. The study drug was unblinded on Day 4. At the end of the four-day period, 13 patients were receiving verapamil (nine patients, 80 mg every 6 hours, and four patients, 120 mg every 6 hours) and all but one were responders. One patient received placebo all through the period of the study and was also considered to be a responder. In the remaining one patient evidence of myocardial necrosis developed after he received a single dose of verapamil (80 mg on Day 2). Except for the prolongation of PR interval in two patients while taking verapamil, no side effects from verapamil therapy were observed. These data demonstrate the efficacy of oral verapamil in reducing episodes of myocardial ischemia in the majority of all patients with rest angina.

Regional coronary angiographic observations during cold stimulation in patient with exertional chest pain: comparison of diameter responses in normal and fixed stenotic vessels

In 12 patients with exertional chest pain, coronary angiography was performed and quantitative measurements coronary artery (CA) diameters were made before and during cold stimulation (four normal CA patients and eight fixed CA stenosis patients). The left main CA; proximal, middle and distal anterior descending and circumflex segments; and small intramyocardial CAs (0.4 to 1.0 mm) usually showed only minimal and similar degree of vasoconstriction (average diameter reduction 6%) during cold stimulation in both normals and CA disease (CAD) patients. Magnitude of vasoconstriction differed among some CA segments measured; the left main CA segment (0 +/- 2%, mean +/- SD) usually did not change while distal segments (-10 +/- 10%) usually demonstrated greatest percentage vasoconstriction. Coronary stenoses and CAs filled by collaterals did not demonstrate increased magnitude of vasoconstriction compared to other CAs. Results of other CA segments were also similar comparing patients with and without CAD. The minimal degree of vasoconstriction observed in these CA segments does not appear to account for the large increase in coronary resistance reported during cold stimulation in CAD patients.

Pathogenesis and pathophysiology of ischemic heart disease

Animal experiments illustrating the effects of coronary artery disease are described. These experiments show marked blunting of reactive hyperremia with 80% of narrowing, and markedly decreased resting blood flow with 90% narrowing of the coronary artery. With 60% stenosis, blunting of hyperemic response occurs with a 5 mm long stenosis and decreased resting blood flow with a 10 mm long stenosis. Further reduction of resting blood flow is demonstrated with serial narrowing. In 6 patients with variant angina, resting myocardial blood flow decreased during episodes of spontaneous angina. Similar results were found in 13 patients with variant angina after ergonovine administration.

Acute effect of intravenous dipyridamole on regional coronary hemodynamics and metabolism

The acute coronary hemodynamic and metabolic effects of intravenous dipyridamole were studied in 13 patients. Total left ventricular (LV), anterior (supplied by the left anterior descending coronary artery) and inferior (supplied by circumflex and right coronary arteries) regional flows and metabolic responses were assessed from the coronary sinus and great cardiac vein. Perfusion to LV regions was classified as potentially "normal" or "abnormal," based on coronary angiographic findings. Before dipyridamole, coronary flow, LV oxygen delivery and lactate extraction in both the normal and abnormal regions were similar. Within 1 minute after injection of 20 mg of dipyridamole by i.v. bolus, total coronary flow increased 51% (p less than 0.05). Fifteen minutes after injection the flow increase persisted. Flow decreased to approximately control level by 20 minutes. The major component of this increased total coronary flow resulted from increased flow in normal regions (75% at 1 minute, p less than 0.05). Mean regional LV oxygen delivery and lactate extraction were not changed significantly in either normal or abnormal regions. However, lactate production occurred more often after dipyridamole in abnormal regions. These results suggest that during dipyridamole-induced hyperemia, regional coronary flow and metabolic responses depend upon the status of the arteries supplying the LV region. Regional differences in flow and metabolism occur independent of major changes in heart rate and aortic and LV pressures.

Quantitation of aortic insufficiency using a catheter-tip velocity transducer

Bidirectional instantaneous aortic root blood flow was measured in 18 patients with aortic insufficiency (AI) using a catheter-tip velocity transducer. The magnitude of AI was quantitated by determining total forward systolic flow from the area of the flow velocity curve above the zero baseline and regurgitant diastolic flow from the curve area below the baseline. Effective forward flow (stroke volume) was calculated as the difference between total forward systolic flow and regurgitant diastolic flow. Regurgitant fraction was determined as the ratio of regurgitant flow to total forward flow. These data were compared with conventional angiographic estimates (1+ to 4+) of the degree of insufficiency. Velocity transducer determination of regurgitant fraction was 26% in the patient with 1+ AI, 37% (31-48%) in 2+ AI, 49% (35-61%) in 3+ AI and 72% in 4+ AI (regurgitant fraction vs angiographic grade, r = 0.84). Regurgitant flow per diastole was 9 ml in the patient with 1+ AI, 39 ml (20-49 ml) in 2+ AI, 57 ml (31-102 ml) in 3+ AI and 183 ml (143 and 223 ml) in 4+ AI (regurgitant diastolic flow vs angiographic grade, r = 0.73). Good correlation (r = 0.90) was found between values of regurgitant flow obtained from the left ventriculogram and those obtained using the velocity transducer. Although the overall association was good, wide, variability in regurgitant fraction and regurgitant flow was found in the 15 patients with 2+ to 3+ AI. These results suggest that the electromagnetic velocity catheter offers a simple technique for quantitating AI.

Magnitude of dilatation of large and small coronary arteries of nitroglycerin

Vasodilatory responses of segments of large epicardial left coronary artery (CA), small intramyocardial CAs (0.3-1.0 mm), coronary stenoses and CAs filled by collaterals were determined in 34 patients. Measurements were made before and after nitroglycerin (0.4 mg, sublingual) by means of quantitative magnification coronary angiography using photospot film and a calibrated 6-power viewing device. The left main CA, proximal, middle and distal anterior descending and circumflex segments, and small CAs showed dilatation that varied in magnitude. When magnitude of dilatation was compared with control diameter of the vessel and its location, control diameter proved to be the significant independent variable. CAs with the smallest control diameter showed the greatest magnitude of vasodilatation. CA branches filled by collaterals had vasodilatation similar in magnitude to that of CAs of comparable control diameter. Although coronary stenoses dilated, the magnitude of dilatation was less than that observed in nonstenosed arterial segments of similar control diameter. When areas of stenosis were excluded, however, results were similar regardless of whether the patient had CA disease. These data indicate that a principal determinant of the CA vasodilatory response to nitroglycerin is the size of the artery before nitroglycerin.

A new temporary atrial pacing catheter inserted percutaneously into the subclavian vein without fluoroscopy: a preliminary report

A permanently formed "J" shaped 6F bipolar electrode catheter specially designed to facilitate temporary atrial pacing was constructed and tested in 15 patients. A pair of rigid, "orienting wings" was fixed to the catheter 28 cm from a large spherical tip electrode to establish directional orientation of the "J" while in the right atrium. Rapid percutaneous introduction is possible with a peel-away sheath via the subclavian vein. Positioning in the right atrium can be accomplished without fluoroscopy. The catheter could be inserted and positioned against the right atrial wall generally in less than three minutes and required little or no additional manipulation for capture. No instance of loss of capture was documented during subsequent continuous monitoring as the catheter remained in place from one to thirteen days. Ease of insertion of this electrode catheter, as well as stability, provided an effective method for temporary atrial pacing without fluoroscopy. This novel catheter design warrants testing in a large patient population by others and could have a potential application to other types of catheter needs.

Effect of diltiazem in patients with variant angina: a randomized double-blind trial

Effects of diltiazem of frequency of angina and nitroglycerin (NTG) consumption were studied in 12 patients with variant angina (rest pain with ST elevation). Either diltiazem in two dosage schedules (120 mg/day and 240 mg/day), or placebo was administered in a randomized double-blind program over 10 weeks. Significant decreases in angina frequency and TNG consumption were observed when diltiazem treatment periods were compared to placebo periods. Furthermore, when placebo periods following diltiazem were compared to placebo periods following placebo, significant "carry-over" effect with respect to reduced angina frequency was observed. No patient had an increase in angina frequency or TNG consumption on diltiazem compared to placebo. No "rebound effects" or changes in blood pressure or heart rate were observed. One patient complained of dry mouth on diltiazem. These findings, although in a limited number of patients, suggest that diltiazem is effective in decreasing angina frequency and TNG consumption in patients with variant angina. These encouraging results warrant evaluation of diltiazem in a larger patient population over a longer time period.

Platelet function studies in coronary artery disease. X. Effect of dipyridamole

To evaluate the effects of dipyridamole on blood platelet function in patients with coronary artery disease, platelet counts and aggregation were examined in aortic and coronary venous blood. Before administration of dipyridamole, platelet counts and aggregation in response to adenosine diphosphate were less (p less than 0.02) in coronary venous than in aortic blood. Dipyridamole administration (100 mg) resulted in an increase in platelet counts and platelet aggregation in coronary venous blood so that the differences in aortic and coronary venous blood values were eliminated. These phenomena were probably related to inhibitory actions of dipyridamole on platelet adhesion to atherosclerotic vessels. To further study the mechanism of action, the direct effects of dipyridamole on in vitro platelet aggregation were evaluated. Although dipyridamole, in the concentrations used, had no effect on in vitro platelet aggregation, it greatly potentiated the aggregation inhibitory actions of exogenous prostacyclin. In vivo potentiation of endogenous prostacyclin and inhibitory actions on platelet adhesion are the most likely mechanisms of the potentially beneficial actions of dipyridamole.

Echocardiographic analysis of systolic and diastolic left ventricular wall motion during transient myocardial ischemia

Left ventricular (LV) wall motion (anterior and posterior) and simultaneous LV pressure were recorded during 30-second left anterior descending (LAD) or circumflex (CX) coronary artery occlusions in open-chest dogs to provide an echocardiographic model of the evolution of wall motion changes during myocardial ischemia. Prominent diastolic echocardiographic motion changes of progressive decrease in LV wall rapid-filling velocities (RFS), slow-filling velocities (SFS), and increased end-diastolic diameter were accompanied by a marked increase in initial and end-diastolic pressures (150% and 70%, respectively; all p less than 0.05). Early (within ten seconds) and progressive decrease in rat (SES), amplitude (E), and duration (TTR) of systolic motion were noted with an increased systolic diameter (p less than 0.05). Ischemic regions developed a characteristic pattern with early relaxation followed by a diastolic inward motion (DIM). These observations confirm and extend other investigators' findings on the motion of the ischemic myocardium and may be applicable to responses to transient myocardial ischemia noted in humans.