Blood velocity in the coronary artery circulation: relation to thromboxane A2 levels in coronary sinus in patients with angiographically normal coronary arteries

Increased plasma soluble adhesion molecules; ICAM-1, VCAM-1, and E-selectin levels in patients with slow coronary flow

BACKGROUND

Inflammation has been reported to be a major contributing factor to many cardiovascular events. In the present study, we aimed to evaluate plasma soluble adhesion molecules; intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin as possible indicators of endothelial activation or inflammation in patients with slow coronary flow.

METHOD

Study population included 17 patients with angiographically proven normal coronary arteries and slow coronary flow in all three coronary vessels (group I, 11 male, 6 female, mean age=48+/-9 years), and 20 subjects with angiographically proven normal coronary arteries without associated slow coronary flow (group II, 11 male, 9 female, mean age=50+/-8 years). Coronary flow rates of all patients and control subjects were documented by Thrombolysis In Myocardial Infarction frame count (TIMI frame count). All patients in group I had TIMI frame counts greater than two standard deviation above those of control subjects (group II) and, therefore, were accepted as exhibiting slow coronary flow. Serum levels of ICAM-1, VCAM-1, and E-selectin were measured in all patients and control subjects using commercially available ELISA kits.

RESULTS

Serum ICAM-1, VCAM-1, and E-selectin levels of patients with slow coronary flow were found to be significantly higher than those of control subjects with normal coronary flow (ICAM-1: 545+/-198 ng/ml vs. 242+/-113 ng/ml respectively, p<0.001, VCAM-1: 2040+/-634 ng/ml vs. 918+/-336 ng/ml respectively, p<0.001, E-selectin: 67+/-9 ng/ml vs. 52+/-8 ng/ml respectively, p<0.001). Average TIMI frame count was detected to be significantly correlated with plasma soluble ICAM-1 (r=0.550, p<0.001), VCAM-1 (r=0.569, p<0.001) and E-selectin (r=0.443, p=0.006).

CONCLUSION

Increased levels of soluble adhesion molecules in patients with slow coronary flow may be an indicator of endothelial activation and inflammation and are likely to be in the causal pathway leading to slow coronary flow.

The no-flow phenomenon during diagnostic coronary angiography

OBJECTIVES

Slow flow of dye in epicardial coronary arteries is not an infrequent finding in patients during routine coronary angiography. The extreme form of this phenomenon, namely, no flow or Thrombolysis in Myocardial Infarction (TIMI) 0-1, is very uncommon with life-threatening consequences. We consider the present report as the first one, to our knowledge, that describes this angiographic entity and how prompt recognition and adequate management prevent certain death in this population.

DESIGN, SETTING, AND PATIENTS

Retrospective review of the cardiac catheterization laboratory database at our medical center. Out of 5700 cardiac catheterizations performed by the authors during the past 5 years, 10 cases (0.17%) were identified as having no flow or very slow flow during their routine diagnostic coronary angiogram.

CASE ANALYSIS

The no-flow phenomenon occurred during the first coronary injection in the left coronary system. We specifically emphasize that none of these cases was a consequence of inadvertent air injection, vasospasm, or coronary dissection. In 80% of our cases, flow was completely absent (TIMI 0), and in two cases (20%) it was very slow and never filling the distal vessel (TIMI 1). Despite immediate recognition and prompt maneuvers and treatment with intracoronary vasodilator administration, 60% of these patients progressed to full cardiopulmonary arrest with all of them having extended cardiopulmonary resuscitation (CPR) and pharmacological treatment. Only one patient required intra-aortic balloon pump (IABP) support and temporary pacemaker. All patients recovered completely with no clinical consequences. Characteristics of patients with this complication are described, and several possible etiologies are analyzed.

CONCLUSIONS

Definite conclusions for the reason of the no-flow phenomenon are not possible at present, despite multiple different theories that could explain it. What is important from the clinical standpoint is that, although rare, it is a potentially life-threatening condition during diagnostic coronary angiography that should be recognized and aggressively treated. We consider the present report as the first one, to our knowledge, that describes this angiographic entity, and how prompt recognition and adequate management prevents certain death in this population.

Coronary hemodynamic and metabolic studies of the coronary slow flow phenomenon

BACKGROUND

The coronary slow flow phenomenon (CSFP) is an angiographic finding characterized by Thrombolysis in Myocardial Infarction (TIMI)-2 flow in the absence of significant large vessel coronary disease. Although clinical and pathological features have been previously described, the underlying pathophysiology has not been fully elucidated. This study investigates the persistence of the phenomenon on serial angiographic studies, coronary hemodynamic findings at rest and during provocative stimuli, and biochemical evidence of inducible myocardial ischemia.

METHODS

Twelve patients with CSFP underwent repeat angiography and coronary sinus canulation that allowed for the assessment of coronary blood flow, transmyocardial lactate, and oxygen extraction. Parameters were assessed at rest and during rapid atrial pacing, cold pressor stimulation, and acetylcholine infusion. Angiographic and coronary hemodynamic findings were compared with 47 patients who underwent angiography and 8 patients who were hemodynamic control subjects, respectively.

RESULTS

Persistent TIMI-2 flow was demonstrated with repeat angiography in only 4 of the patients. However, the corrected TIMI frame count remained delayed compared with that in control subjects. Furthermore, resting coronary sinus oxygen saturation was low compared with control subjects (23% +/- 4% vs 31% +/- 4%; P <.01), reflecting an increased basal coronary vasomotor tone. The coronary vasodilatory response to atrial pacing was similar to that in control subjects; however, several patients exhibited abnormal vasomotor responsiveness to cold pressor and acetylcholine stimuli. There was no evidence of nett myocardial lactate production with atrial pacing.

CONCLUSION

The CSFP is associated with a chronically elevated resting coronary microvascular tone, even when symptoms are relatively quiescent.

Changes in cardiac autonomic activities in patients with syndrome X. A study of spectral analysis of heart rate variability

The present study was designed to assess cardiac autonomic activities, coronary microvascular function, and their relationship in patients with syndrome X. Control of coronary blood flow is complex, and impaired coronary flow reserve has been attributed as the cause of myocardial ischemia in patients with syndrome X. It is unknown whether cardiac autonomic activities are altered in the presence of coronary microvascular dysfunction in patients with syndrome X. Eighteen patients with syndrome X were studied. Great cardiac vein flow was measured by the thermodilution method and the coronary flow reserve was determined by intravenous dipyridamole (0.56 mg/kg) infusion. Twenty-four-hour ambulatory electrocardiograms were obtained in a drug-free state. Another 14 age- and sex-matched normal subjects served as a control group. The amplitude (in ms) of ultralow (ULF), very-low (VLF), low (LF), and high (HF) frequency bands and total spectra of heart rate variability were measured for twenty-four-hour and every four-hour interval of the day.

Progression of coronary endothelial dysfunction in man and its potential clinical significance

Endothelial injury represents an important factor in the initiation of atherosclerosis and is associated with abnormal vasomotor responses (= dysfunctional endothelium) to a variety of stimuli. Therefore, the evaluation of endothelial function may provide a means to detect early vascular alteration preceding overt atherosclerotic lesions. To test this clinically important hypothesis, we studied the coronary vasomotor responses to three different endothelium-dependent stimuli in patients with different early stages of coronary artery disease: first, increasing doses of intracoronary infusion of acetylcholine (ACH) (10(-8), 10(-7), 10(-6) M); second, transient increases in coronary flow causing flow-dependent dilation by injection of papaverine into the midportion of the left descending artery (exposing the proximal segment of this vessel to increased flow, but not to papaverine); and third, sympathetic stimulation by cold pressor test. Coronary diameters were assessed by repeated coronary angiography and quantitative angiography, blood flow velocity (and subsequent calculation of blood flow) was obtained by intracoronary Doppler. In normal individuals, all three stimuli elicited epicardial artery dilation. In patients with smooth coronary arteries, but hypercholesterolemia, a substantial vasoconstriction was observed in response to ACH, whereas the response to cold pressor test and increases in flow was normal, that is, vasodilation occurred. In patients with angiographically visible atherosclerosis, acetylcholine and cold pressor test exerted coronary vasoconstriction. Moreover, flow-dependent, endothelium-mediated dilation was attenuated in those patients demonstrating visible luminal irregularities in the vessel under study. In patients with hypercholesterolemia, substantial endothelial dysfunction (as assessed by attenuated blood-flow increase in response to acetylcholine) was demonstrated in the coronary microcirculation. Thus, progression of endothelial dysfunction occurs during the early course of development of coronary atherosclerosis. Utilizing quantitative coronary angiography and the intracoronary Doppler technique, these early functional alterations can be identified safely at a stage when atherosclerotic lesions are not detectable by angiography. This may be useful in designing early effective interventions which restore endothelial function and prevent the occurrence of overt atherosclerosis.

Abnormal coronary vasomotion during exercise in patients with normal coronary arteries and reduced coronary flow reserve

A reduced coronary flow reserve has been reported in patients with ischemialike symptoms and normal coronary arteries. In 13 such patients, both coronary vasomotion and flow reserve were studied. The luminal area of the proximal and distal third of the left anterior descending and left circumflex artery were determined by biplane quantitative coronary arteriography using a computer-assisted system. Patients were studied at rest, during submaximal supine bicycle exercise (4.0 minutes, 116 W), and 5 minutes after sublingual administration of 1.6 mg nitroglycerin. Heart rate, mean pulmonary pressure, and mean aortic pressure as well as the percent change of both proximal and distal luminal area were determined. In 10 of the 13 patients, coronary sinus blood flow was measured by coronary sinus thermodilution technique at rest and after dipyridamole infusion (0.5 mg/kg in 15 minutes) 10 +/- 5 days after quantitative coronary arteriography. Coronary flow ratio (dipyridamole/rest) and coronary resistance ratio (rest/dipyridamole) were determined in these patients. Patients were divided into two groups according to the behavior of the coronary vessels during exercise (vasodilation, group 1; vasoconstriction, group 2). Coronary vasodilation of the proximal (luminal area +26%, p less than 0.001) and distal (+45%, p less than 0.001) artery was observed in seven patients (group 1) during exercise and after sublingual nitroglycerin (+46%, p less than 0.001; and +99%, p less than 0.001, respectively). In group 2 (n = 6), however, there was coronary vasoconstriction of the distal vessel segments (-24%, p less than 0.001) during exercise, whereas the proximal coronary artery showed vasodilation (+26%, p less than 0.001) during exercise. After sublingual nitroglycerin, both vessel segments elicited vasodilation (distal coronary, +44%, p less than 0.001; proximal coronary artery, +47%, p less than 0.001). Coronary flow ratio amounted to 2.5 in group 1 and 1.2 in group 2 (p less than 0.05) and coronary resistance ratio to 2.7 in group 1 and to 1.2 in group 2 (p less than 0.05), respectively. Thus, among patients with ischemialike symptoms and normal coronary arteries, there is a group of patients (group 2) with an abnormal dilator response of the distal coronary arteries to the physiologic dilator stimulus of exercise and a reduced dilator capacity of the resistance vessels after dipyridamole (abnormal coronary vasodilator syndrome). The nature of this exercise-induced distal coronary vasoconstriction is not clear but might be due to an abnormal neurohumoral tone that may cause or contribute to the blunted vascular response during exercise.