Athanassios Antonopoulos

Relation between changes in blood flow of the contralateral coronary artery and the angiographic extent and function of recruitable collateral vessels arising from this artery during balloon coronary occlusion

OBJECTIVES The purpose of this study was to investigate changes in the magnitude of blood flow through the contralateral coronary artery in relation to the development of recruitable collateral vessels arising from this artery to supply a balloon-occluded coronary vessel. BACKGROUND Recruitable collateral vessels have been shown to emerge suddenly to supply an occluded coronary artery, but their physiologic effect cannot always be predicted angiographically. METHODS Twenty-four patients were studied during four successive balloon dilations for single left anterior descending coronary artery stenosis. Before and during each balloon occlusion, blood flow in the proximal right coronary artery was measured by intracoronary Doppler flow velocimetry and quantitative coronary angiography. Estimates of chest pain and ST segment elevation were also obtained. RESULTS Fourteen patients developed angiographically visible recruitable collateral vessels (high grade in 6 [group III], low grade in 8 [group II]), whereas 10 patients (group I) did not. During the four successive balloon occlusions, the right coronary artery flow showed transient reproducible increases in group III (first occlusion 66.4 +/- 36.8%, fourth occlusion 64 +/- 23.9%, all p = 0.036), progressive increases in group II (from first occlusion 17.9 +/- 26.6% [p = 0.08] to fourth occlusion 60.4 +/- 35.9% [p = 0.014]) and no significant changes in group I. Between the first and the fourth occlusion, the severity of chest pain and the magnitude of ST segment elevation declined significantly in group II but did not change in groups I and III. CONCLUSIONS During balloon coronary artery occlusion, the transient appearance of recruitable collateral vessels is associated with a transient increase in blood flow through the collateral donor artery. This increase in coronary flow appears to reflect collateral function better than the angiographic assessment, especially in patients with poor collateral vessel recruitment.

Sex differences in the anatomy of coronary artery disease

In a prospective study, the extent and severity of coronary artery disease (CAD) as well as the location of coronary stenoses were studied comparatively, in relation to age and sex, in 192 consecutive women vs 543 selected men, who all underwent coronary angiography during the same time period, and who were found to have significant CAD. Overall, the age of women (59 +/- 8 years) was higher than that of men (55 +/- 8 years), p < 0.001. Also, the prevalence of smoking was higher in men (81% vs 31%, p = 0.0000) and that of diabetes mellitus in women (29% vs 12%, p = 4 x 10(-6)). In addition, women over 50 years old had a higher incidence of hypertension (51% vs 32%, p = 6 x 10(-5)). Although in both sexes the prevalence of multivessel CAD increased with age, the prevalence of one-vessel CAD was significantly more and that of three-vessel CAD significantly less common in women than in men, both overall (35% vs 16%, p = 4 x 10(-8) and 36% vs 54%, p = 2 x 10(-5), respectively) and in all age subgroups. However, the location of coronary stenoses did not show important differences between men and women with the left anterior descending being the most frequently involved artery. Furthermore, the calculated Gensini index, which reflects cumulatively the extent, severity and location of coronary stenoses, was significantly higher in men (59.2 +/- 34.6 vs 52.2 +/- 36.2, p = 0.03), implying more severe and extensive CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood pressure elevation after phenylephrine infusion may adversely affect myocardial perfusion in patients with coronary artery disease.

BACKGROUND Although blood pressure is a major determinant of myocardial oxygen-demand, little information is currently available regarding the changes in blood pressure (BP) during myocardial ischemia. Since BP elevation may cause left ventricular (LV) wall stress and an increase in oxygen demand, infusion of an alpha-adrenergic agonist, such as phenylephrine (PH), may provoke changes in myocardial perfusion in coronary artery disease (CAD) patients. As the effects of BP changes alone on myocardial perfusion have never been assessed by thallium-201 (Tl) scintigraphy, we investigated the effects of BP elevation after PH infusion, in order to study the hypothesis that pressure loading alone without increases in heart rate, may provoke transient impairment of regional myocardial perfusion, in CAD patients. PATIENTS AND METHODS Forty-one (41) patients with angiographically documented CAD, aged 54+/-8 years, were included in our study. Each patient was given, without any complications, a PH (0.1 mg/ml) dose infused at a rate of 0.8 ml/mm, determined by a standardisation procedure and producing a mean blood pressure elevation of approximately 30% above baseline levels and a heart rate response to levels of no less than 50 bpm. One minute after the desired blood pressure and heart rate responses were reached, 2 mCi of Tl were injected and the PH infusion continued until the termination of the test. Tl scintigraphy was performed both 2 min after Tl injection and 4 h later, while the results were correlated to coronary angiography findings. RESULTS PH scintigraphy produced 152 total defects. The mean perfusion defect size (%) was 14+/-12 and was directly related to the number of diseased vessels, i.e., 2% for one-vessel disease, 15% for two-vessel disease and 25% for three-vessel disease (P<0.05). The lowest percentage Tl activity values were 56+/-14 and were inversely related to the number of diseased vessels (P<0.01). The mean Tl lung counts/pixel values were 25+/-8 while it increased as the number of diseased vessels increased (P<0.01). The mean lung/heart ratio values were 0.31+/-0.08 while it increased as the number of diseased vessels increased (P<0.01). CONCLUSION BP elevation after PH loading, produces a significant impairment of myocardial perfusion, that correlates well with the extend of angiographic findings.

Systolic time intervals after phenylephrine administration for early stratification of patients after acute myocardial infarction

This study was designed to assess the usefulness of the changes in left ventricular (LV) systolic time intervals after phenylephrine administration for detecting high-risk patients soon after acute myocardial infarction by correlation with the angiographic and ventriculographic findings. The procedure was performed in 76 consecutive patients (group I) on the fourth postinfarction day and in 12 normal subjects (group II) free of coronary artery disease. In 20 patients with LV ejection fraction < or = 40% (subgroup IA) the preejection period (PEP)/LV ejection time (ET) ratio increased from 0.410 +/- 0.107 to 0.535 +/- 0.102 (p = 0.01) after phenylephrine, whereas in the remaining 56 patients (subgroup IB) with LV ejection fraction > 40% and in the 12 normal subjects the PEP/LVET increased nonsignificantly. Of patients with LV ejection fraction > 40% a subset of 20 patients was distinguished with proximal stenosis in both left anterior descending and either a dominant right or left circumflex coronary artery (subset IB-a). In these the PEP/LVET increased from 0.347 +/- 0.056 to 0.445 +/- 0.019 (p = 0.0001) after phenylephrine, whereas in the remaining 36 patients (subset IB-b) without proximal lesions in 2 main arteries the PEP/LVET increased nonsignificantly. In conclusion, the PEP/LVET response to phenylephrine administration early after acute myocardial infarction is a precise, safe, noninvasive bedside method for early stratification of these patients.

Thallium-201 for detection of myocardial viability: comparison of early postexercise reinjection and imaging with 4 and 18-24 hours redistribution imaging.

To evaluate the efficacy of an early 201Tl reinjection and imaging protocol for reducing the need for conventional 4-hour or optimal 24-hour redistribution imaging (RI) and detecting of myocardial viability, we compared the results of early postexercise Tl reinjection and imaging with those of 4- and 24-hour RI in 74 consecutive patients aged 55 ± 9 years (mean ± SD) who were assessed for myocardial ischemia. One millicurie of Tl was injected promptly after completion of the initial postexercise imaging (PEX) and three additional sets of images were acquired 1, 4 and 18–24 h later. A total of 2,368 segments were evaluated. On PEX, 390 (17%) segments showed defects, of which 287 (74%) showed enhanced Tl uptake at 1-hour RI; 89 (23%) did not change and 14 (4%) showed reverse redistribution. Of the 103 persistent defects, only 27 (7%) showed further fill-in of Tl; 62 (16%) segments showed reverse redistribution at 4-hour RI while at 18- to 24-hour RI 17 (4%) and 47 (12%) segments showed further fill-in of Tl and reverse redistribution, respectively. Finally, after analysis of 4- and 18- to 24-hour RI, the diagnosis changed from myocardial necrosis to ischemia in only 2 (3%) patients. In conclusion, these results suggest that by eliminating the need for an additional delayed set of images for detection of myocardial viability, this protocol reduces the total investigation procedure, is more convenient for the patient, increases patient turnover and expedites the decision-making process.

Plasma atrial natriuretic factor in uncomplicated acute myocardial infarction

Plasma atrial natriuretic factor (ANF) levels were measured in 29 patients who had normal atrial hemodynamics on days 4 and 8 after an uncomplicated acute myocardial infarction (AMI). All patients had increased ANF levels on day 4. On day 8 of the ANF levels had declined significantly to normal values in 14 patients with enzymatically smaller AMI and higher ejection fractions (> or = 40%), while they remained elevated in 16 patients with larger AMI and lower ejection fractions (< 40%). The study data are compatible with increased secretion of ANF by the more extensively damaged left ventricles in AMI.