Blood flow velocity in donor coronary artery depends on the degree and pattern of collateral vessel development: a study using thrombolysis in myocardial infarction frame count method.

To understand the influence of collateral vessels on the coronary flow, TIMI frame count (TFC) method was applied as a measure of mean coronary blood flow velocity in artery giving collateral blood supply to the other artery in angiograms of 76 patients with single occluded coronary artery: RCA giving collaterals to occluded LAD or LAD giving collaterals to occluded RCA. As a control group, TFC was applied in angiograms of 30 patients with mild or no coronary artery disease. TFC was lower (faster blood flow) in LAD giving collaterals to occluded RCA (43 patients) than in LAD in control group (21.8 +/- 10.5 vs. 33.9 +/- 20.8 frames; P < 0.01). Higher degree of collateral vessels (Rentrop classification) and mixed- and distal-type collaterals (through the interventricular septum and heart apex) was associated with lower TFC. There was no difference in TFC in the RCA giving collaterals to an occluded LAD (33 patients) compared to the TFC in RCA in control group (16.6 +/- 9.0 vs. 18.5 +/- 6.0; P = NS), even in angiograms with higher degree of collateral vessel development. TFC was lower (faster blood flow) only in subgroups with mixed (proximal and distal types together in the same patient) and distal (through the interventricular septum and the apex of the heart) collateral types. A delayed contrast appearance in occluded LAD compared to occluded RCA has been found (35.1 +/- 16.1 vs. 20.2 +/- 7.3 frames; P < 0.001) with earlier contrast appearance in occluded LAD when proximal collateral vessels (through the conal and acute marginal branches of RCA) were presented. The coronary flow in donor arteries depends not only on the degree but also on the pattern of collateral vessels. The simple TFC method may facilitate the study of collateral filling pattern and offer insight into the influence of collaterals on the ventricular function.     

Coronary collateral circulation

The occurrence and influence of coronary collateral circulation and obstruction of the supplying coronary arteries on left ventricular contractility, prevalence of myocardial infarction, and bicycle exercise ergometer test were studied in a random sample of 286 patients with angiographically documented coronary artery disease. Collaterals appeared increasingly in all three main coronary arteries with grade of obstruction. The highest prevalence of collaterals occurred in stenosis of the right coronary artery (60%), followed by the left descending artery (45%); they occurred least in the left circumflex artery (21%) (p less than 0.001). The frequency of intra-arterial collateral circulation was 42%, 11%, and 12%, respectively (p less than 0.001). With total occlusion of the left anterior descending coronary artery, 22% of the patients had normokinetic anterior and apical left ventricular wall when collaterals were present. More often, the inferior wall showed normal contraction with total occlusion of the right coronary artery and collaterals [52%, p less than 0.001 compared with left anterior descending artery (LAD)]. The prevalence of inferior myocardial infarction was 39%, with collateral circulation to the totally occluded right coronary artery. The respective prevalence of anterior infarction and total occlusion in the left coronary artery was 58% (p less than 0.02). The presence or absence of collaterals had no obvious influence on ST-segment response during bicycle ergometer test. In triple-vessel disease, peak work capacity was better when collaterals to LAD were not jeopardized (427 kpm) than when jeopardized (321 kpm) (p less than 0.02).     

Preservation of left ventricular function in patients with total occlusion of the left anterior descending coronary artery and wide-caliber distal vessel filling by collateral vasculature

The segmental ventricular function of 76 patients with total occlusion of the left anterior descending coronary artery (LAD) was analyzed to establish the relationship between ventricular function and the presence and angiographic appearance of the collateral circulation. The relationship between function and collateral supply was found to be significant (P less than .01). The only angiographic feature of the collateral vasculature that was associated with preserved function was the caliber of the distal LAD. Wide-caliber vessels were more likely to be associated with preserved ventricular function than thin vessels (P less than .01). In contrast, both rapidly filling collateral arteries and slow filling vessels were associated with preserved ventricular function. Collateral supply maintenance was significantly associated with preserved ventricular function, even when the collaterals arose from stenotic coronary arteries. Furthermore, despite marked differences in ventricular function between the base and apex of the heart, there was a true relationship between preserved ventricular function and the presence of collateral vessels for all segments of the anterior wall. These findings may be relevant to clinical decision making and to proper interpretation of studies of ventricular function following LAD occlusion.     

Coronary collateral vessels: Spectrum of physiologic capabilities with respect to providing rest and stress myocardial perfusion,maintenance of left ventricular function and protection against infarction

The physiologic significance of coronary collateral vessels was evaluated in 91 patients with stable coronary artery disease. Four physiologic variables were assessed in the distribution areas of 101 totally occluded coronary arteries associated with angiographically defined collateral vessels. These variables included myocardial perfusion at rest and during stress, left ventricular wall motion and the presence or absence of myocardial infarction. These 101 collateralized areas of myocardium were classified into two major groups on the basis of normal (43 areas) or abnormal (58 areas) myocardial perfusion at rest. Among the 43 areas with normal perfusion at rest, three or more variables were normal in 37 instances (86 percent) and all variables were normal in 17. Of 58 areas with abnormal perfusion at rest, three or more variables were abnormal in 47 (81 percent), and all four variables were abnormal in 32. Although the results were generally concordant when all variables were assessed as a group, significant discrepancies existed if each variable was compared individually with resting perfusion. Of the 43 areas with normal resting perfusion 14 (33 percent) had stress defects, 15 (35 percent) had wall motion abnormalities and 5 (12 percent) showed electrocardiographic evidence of myocardial infarction. Of the 58 areas with abnormal resting perfusion 5 (9 percent) had normal stress perfusion, 16 (28 percent) had normal wall motion and 22 (38 percent) lacked electrocardiographic evidence of infarction. The presence or absence of significant coronary artery disease distal to the origin of a collateral vessel, the extent of coronary artery disease in all coronary vessels and the angiographic appearance of collateral vessels were not helpful in defining the significance of a collateral vessel.These results indicate that the functional significance of collateral vessels varies considerably. Collateral vessels in many patients may be highly effective in maintaining myocardial perfusion and left ventricular function and preventing infarction; in others, collateralization may be of no significance. The use of multiple variables as a group rather than individually provides meaningful information regarding the physiologic significance of a collateral vessel and complements the coronary angiogram, which is not uniformly helpful in making this assessment.     

Coronary collaterals and left ventricular function early after acute transmural myocardial infarction

The coronary collateral circulation and ventricular function,segmental wall motion and infarct size, were investigated fromhemodynamic and angiographic data in 126 patients with acutetransmural myocardial infarction and complete obstruction ofa major coronary vessel. The patients were divided into twogroups: 74 with obstruction of the right coronary artery and52 with obstruction of the left anterior descending artery.The collateral circulation was rated as absent, poor, fair oradequate: two weeks after infarction, collateral vessels wereobserved in only 27% (poor 15.4%, fair 5.8%, adequate 5.8%)of the patients with an anterior myocardial infarction and inonly 35% (poor 13.5%, fair 16.4%, adequate 4.5%) of the patientswith an inferior myocardial infarction. In both groups of patients, the presence of collateral vesselshad no significant influence on the following parameters: leftventricular performance (left ventricular end-diastolic pressure,left ventricular enddiastolic volume, ejection fraction andmean velocity of fiber shortening), extent of abnormally contractingsegment and segmental wall motion. After anterior myocardialinfarction, there was an insignificant trend to lesser myocardialdamage in patients with coronary collaterals. Thus, coronary collaterals are infrequent in patients with acutetransmural myocardial infarction and total obstruction of acoronary vessel; in these patients we conclude that the collateralshave no effect either on left ventricular function or on thesize of the infarction.     

Bidirectional function of coronary collateral channels in conscious dogs

STUDY OBJECTIVE--The aim was to investigate the bidirectional functional adequacy of collateral perfusion in conscious dogs. DESIGN--Left circumflex coronary artery (LCCA) occlusions of 1 or 2 min duration were repeated to stimulate the development of collateral perfusion to the LCCA area, and the left anterior descending coronary artery (LAD) was occluded once daily to evaluate the development of retrograde LCCA-LAD flow. SUBJECTS--7 male mongrel dogs were used, weight 25-28 kg. MEASUREMENTS AND MAIN RESULTS--Coronary collateral flow from the LCCA to the LAD perfusion area was measured as the abrupt decrease in the LCCA flow (implanted Doppler transducer) upon release of a brief LAD occlusion. Measurements were repeated daily during the development of collaterals induced by repeated, brief occlusions of the LCCA. After 35(SD17) days of such occlusions; there was no sustained reduction in LCCA regional myocardial function during an LCCA occlusion, and reactive hyperaemic repayment following the occlusion was negligible. Before and after collateral development, the LCCA to LAD collateral flow increased from 1.1(0.2) to 8.6(5.1) cm.s-1. LAD systolic segment shortening during the LAD occlusion increased from 2.1(2.0)% (first occlusion) to 19.3(8.6)% (last occlusion). CONCLUSIONS--LAD to LCCA collaterals serve as functionally significant bidirectional perfusion conduits, and monitoring of collateral perfusion development is practical by measuring the step reduction in LCCA flow upon abrupt release of an LAD occlusion.     

Visualization of isolated conus artery as a major collateral pathway in patients with total left anterior descending artery occlusion

To examine the existence of isolated conus artery (ICA) as a source of collateral circulation, we selectively visualized the ICA in patients with left anterior descending coronary artery (LAD) occlusion using a no. 5 French catheter. One hundred and fifty patients with a total LAD occlusion were selected from 639 consecutive patients who had diagnostic coronary angiography during an 18-month period; the ICA was found in 45 patients. Among these patients, 30 showed the ICA as a collateral vessel supplying the distal LAD. In nine of these patients, conventional left and right coronary angiography did not reveal any other significant collateral vessels, and the distal LAD was perfused mainly by the collaterals from the ICA. No serious complications such as ventricular fibrillation or myocardial infarction occurred during these procedures. These results indicate that the selective ICA visualization is clinically important when conventional left and right angiography does not demonstrate collaterals to the obstructed LAD.     

The Role of Coronary Collaterals in Chronic Total Occlusions

A chronic total occlusion (CTO) describes a completely occluded coronary artery. This type of lesion is found in about 18% of all significant lesions in patients with coronary artery disease. A system of collateral connections are observed in almost all of these lesions, which have the capacity to prevent myocardial necrosis and may even uphold metabolic supply to the territory distal to an occlusion to maintain full contractile capacity. During exercise these collaterals are limited in their functional reserve, and more than 90% of patients with a well collateralized occlusion will experience ischemia. in the absence of ideal animal models that mimic the human collateral circulation, we need to rely on studies in man. The knowledge of collateral physiology in man has increased considerably over the past two decades with the advent of intracoronary sensors of coronary pressure and flow velocity. A number of basic physiologic questions have been answered by these studies. The blood supply through coronary arteries depends on a complex array of in general serial resistance systems, with an additional array of multiple parallel resistances on the collateral level.There seems to be a great interindividual variability in the ability to recruit preformed collateral connections in the case of an epicardial occlusion. Collateral function can develop to a similar functional level in patients post myocardial infarction with large akinetic territories as it does in patients with normal preserved regional function. The presence of viability is thus not a prerequisite for collateral development. The question of practical relevance in the era of interventional therapy of chronic occlusions is also, whether a patient with coronary artery disease will remain protected by collaterals after removing the obstruction in the collateralized artery, or whether collaterals regress and lose their functional capacity. Both developments are observed again mainly depending of individual predisposition.     

冠状动脉侧支循环某些相关因素的临床研究

目的研究冠状动脉侧支循环在冠状动脉完全闭塞与次全闭塞血管病变中的形成情况,观察心肌梗死病史、心肌肥厚及糖尿病对侧支循环形成的影响以及侧支循环对心肌的保护作用。方法回顾分析了我院一年内409例经冠状动脉造影证实的冠状动脉完全或次全闭塞患者,先按有无心肌梗死病史将患者分为两组,对照分析侧支循环形成的良好率,及心功能相关因素方面的差异。再按有无心肌肥厚、有无糖尿病病史分别分为两组,观察其对侧支循环形成的影响。结果冠状动脉完全与次全闭塞对比侧支循环形成的良好率有显著差异。有心肌梗死与无心肌梗死病史两组侧支循环形成的良好率比较无显著差异。两组的左心室舒张末期内径、左心室射血分数、室壁运动异常发生率及室壁瘤形成均有显著差异。而有心肌梗死病史者侧支循环良好组与不良组比较左心室舒张末期内径、左心室射血分数无差异。有无心肌肥厚对侧支循环形成良好率无差异。有糖尿病史者侧支循环血流良好率明显高于无糖尿病史者,且有显著差异。结论冠状动脉侧支循环的开放依赖于冠状动脉血管的完全或次全闭塞。冠状动脉缓慢闭塞下形成的侧支循环对心肌、心功能有保护作用。糖尿病有利于侧支循环的发展。     

Attenuation of nitroglycerin-induced coronary hyperemic blood flow in patients with left anterior descending coronary collaterals

Although intracoronary nitroglycerin (NTG) is frequently administered to patients having occluded coronary arteries undergoing invasive procedures such as percutaneous transluminal coronary angioplasty or thrombolysis, the extent of NTG-induced augmentation of myocardial blood flow in patients with collaterally filled occluded arteries is incompletely understood. To examine NTG-induced increases in coronary blood flow in patients with occluded left anterior descending coronary arteries (LAD), coronary and systemic hemodynamics were measured during bolus administration of NTG into the left coronary artery in 10 patients with normal LAD (Group 1), 11 patients with greater than 70% and less than 100% narrowing of the LAD (Group 2), and 10 patients who had total occlusion of the LAD with angiographic collateral filling and anterior ventricular wall motion abnormalities (Group 3). NTG increased anterior regional great vein flow (thermodilution) from 72 +/- 19 to 140 +/- 60 ml/min (p less than 0.05), 67 +/- 27 to 108 +/- 66 ml/min (p less than 0.05), and 59 +/- 27 to 74 +/- 36 ml/min (p = NS vs. control, p less than 0.05 vs. peak flow for Group 1) with relative increases from control of 91 +/- 41%, 56 +/- 34%, and 25 +/- 22% for the three groups, respectively. The percent change for Group 3 was significantly lower than both Groups 1 (p less than 0.01) and 2 (p less than 0.05). These data indicate that myocardial hyperemic blood flow responses to intracoronary NTG are markedly attenuated in patients with occluded but collaterally supplied vessels. During invasive procedures in these patients, although significantly attenuated, intracoronary NTG may potentially provide a beneficial effect by augmenting blood flow through collaterals or in adjacent regions.     

Determinants of infarct size in patients successfully treated by intracoronary thrombolysis

In 125 patients successfully treated by intracoronary thrombolysis, data were analyzed to determine the amount of regional wall motion impairment. In 85 patients with complete occlusion of the affected vessel and successful recanalization, ventriculographic study could be performed immediately after recanalization of the vessel and repeated 3 days thereafter. Unexpectedly, no correlation could be seen between the amount of wall motion impairment and the time interval of coronary vessel occlusion. For assessment of other influencing factors two subgroups were analyzed, one with large infarction despite short occlusion time and the other with small infarction despite long occlusion time. The significant differences between these two groups was in regard to the occluded coronary vessels: In the first group, most patients had anterior infarctions caused by left anterior descending (LAD) occlusion, whereas in the second group, there were no LAD occlusions at all. According to the data that we compiled, the location of the occluded coronary vessel was the most important factor in determining infarct size. Taking this into account, recovery of the impaired wall motion up to the third day after infarction was separately analyzed in LAD occlusion or inferior infarction and was found to be more pronounced in the first. Immediate recovery after recanalization however, which could be analyzed in 40 patients who had angiographic studies before recanalization as well as afterwards, was more pronounced in inferior infarction.     

Functional significance of coronary collateral circulation during dynamic exercise evaluated by thallium-201 myocardial scintigraphy.

Sixty-five patients with angiographically documented coronary artery disease were investigated by thallium-201 (201Tl) scintigraphy to determine the role of the collateral circulation during dynamic exercise. Fifty-three patients had complete proximal occlusion of at least one major coronary artery. One patient had total occlusion of all three major coronary arteries. Sixty-four collateral channels were identified, graded, and compared with corresponding regions of the myocardial scintigram. Tracer uptake was also graded and classified as various degrees of protection from ischaemia. A significant correlation between good collaterals with complete protection and poor or absent collaterals with no protection was noted. Seventeen patients (20 occluded vessels) had total coronary occlusion without myocardial infarction. Collaterals conferred protection in 9/15 occlusions whereas no protection was seen in five occlusions without collaterals. There was no difference in the protective role of homocoronary and heterocoronary collateral vessels. Hypertrophy of the first septal left anterior descending perforator conferred significant protection from ischaemia in contrast to bridging collaterals and ghosting. During exercise the right coronary bed is preferentially protected from ischaemia, in contrast to the left anterior descending territory. This probably reflects the direction of a transmural flow gradient between left and right ventricles during exercise.     

ST segment response to acute coronary occlusion: coronary hemodynamic and angiographic determinants of direction of ST segment shift

To assess the relationship between the direction of ST segment response to transient coronary occlusion and collateral function, we studied 25 patients with diagnostic ST segment changes during transient occlusion of the proximal left anterior descending artery (LAD). Electrocardiographic leads I, II, V2, and V5; left ventricular filling, aortic, and distal coronary pressures; and great cardiac vein flow were measured during percutaneous transluminal coronary angioplasty (PTCA) of the LAD. During a 1 min LAD balloon occlusion, 16 patients had reversible ST elevation (group I) and nine patients had ST depression (group II). The ST responses in individual patients were consistent during repeated occlusions, and ST depression never preceded ST elevation. Angiography before PTCA showed less severe LAD stenosis in group I (69 +/- 15%) than in group II (88 +/- 10%; p less than .01) and collateral filling of the LAD in no group I patient but in six of nine patients in group II (p less than .01). During LAD occlusion, determinants of myocardial oxygen demand (left ventricular filling pressure, aortic pressure, heart rate, and double product) were similar in both groups. Group I patients, however, had lower distal coronary pressure (25 +/- 8 vs 41 +/- 16 mm Hg) and residual great cardiac vein flow (33 +/- 14 vs 51 +/- 22 ml/min) and higher coronary collateral resistance (3.1 +/- 2.1 vs 1.5 +/- 0.8 mm Hg/ml/min) than group II patients (all p less than .05). In patients with ST elevation during LAD occlusion, stenosis before PTCA was less severe, visible collaterals were not present, and hemodynamic variables during LAD occlusion reflected poorer collateral function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protective role of collaterals in patients with coronary artery occlusion

We reviewed the clinical, hemodynamic and angiographic data of 105 patients with right coronary artery occlusion and of 82 patients with left anterior descending coronary artery occlusion, subdivided into 3 groups by the presence and quality of collaterals to the occluded coronary (absent, poor or good collaterals). We found that patients with right coronary artery occlusion and good collaterals had a lower frequency of diaphragmatic myocardial infarction (60%) than patients with absent collaterals (100%) (P < 0.01). In addition, in patients with old diaphragmatic myocardial infarction, both poor and good collaterals were associated with a lower frequency of severe asynergy of the diaphragmatic left ventricular segments at left ventriculography (54% and 14%, respectively), compared to patients with no collaterals to the right coronary artery (92%, P < 0.02 vs. poor collaterals, P < 0.001 vs. good collaterals). In contrast, in patients with left anterior descending coronary artery occlusion, the presence of either poor or good collaterals to the left anterior descending coronary artery was not associated with a lower frequency of old anterior myocardial infarction, or, in patients with old anterior myocardial infarction, with a less severe asynergy of the anterior left ventricular segments.Our results suggest that collaterals are effective in protecting the diaphragmatic left ventricular wall in patients with right coronary artery occlusion, but not the anterior left ventricular wall in patients with left anterior descending coronary artery occlusion.     

The influence of angiographically demonstrated coronary collaterals on the results of stress echocardiography

Previous studies using thallium-201 scintigraphy have suggested that angiographic coronary collaterals can protect against the development of stress-induced perfusion abnormalities, but the effect of collaterals on stress echocardiography (SECHO) has not been determined. In this study, 21 consecutive patients referred for cardiac catheterization underwent SECHO and coronary angiography. Of the 21 study patients, there was a total of 16 significantly obstructed coronary arteries (≥ 70% stenosis) in 14 patients. SECHO revealed stress-induced wall motion abnormalities in the distribution of seven of nine obstructed coronary vessels without angiographic collaterals, but in only one of seven vessels with collaterals (p ≤ 0.05). Six of eight obstructed vessels not associated with a stress-induced wall motion abnormality had collaterals, whereas only one of eight obstructed vessels associated with a stress-induced wall motion abnormality had collaterals. We conclude that (1) angiographically demonstrated coronary collaterals can protect against the development of stress-induced wall motion abnormalities despite the presence of a high-grade coronary artery obstruction, and (2) the lack of a stress-induced wall motion abnormality on SECHO in the perfusion territory of an obstructed vessel may suggest the presence of adequate collateral perfusion.     

Coronary collateralization: determinants of adequate distal vessel filling after arterial occlusion

BACKGROUND: The protective effect of collateral vessels in coronary artery disease (CAD) is well established. Little is known, however, about factors that influence collateral formation. METHODS: We studied the coronary angiograms of 200 consecutive patients with single-vessel coronary artery occlusion. Patients were excluded if obstructive stenoses were present in other vessels or if prior revascularization had been undertaken. Collateral circulation to the occluded artery was graded as 'poor' (no or incomplete filling) or 'rich' (complete filling). Patient characteristics, including mode of presentation, medications and CAD risk factors, were assessed. RESULTS: Positive univariate correlates of rich collaterals included increasing age [odds ratio (OR) 1.03, P = 0.016], 'statin' use (OR 2.50, P = 0.005), nitrate use (OR 1.96, P = 0.034), calcium-channel blocker (CCB) use (OR 4.07, P < 0.001), presentation with stable angina (OR 2.34, P = 0.006), longer time since diagnosis of CAD (OR 1.12, P = 0.002) and history of hyperlipidemia (OR 3.55, P < 0.001). Significantly poorer collateralization was observed in the setting of acute myocardial infarction (MI) (OR 0.23, P < 0.001), diabetes mellitus (OR 0.33, P = 0.003), impaired left ventricular function (OR 0.64, P = 0.015) and occlusion of the left anterior descending coronary artery (LAD) (OR 0.28, P < 0.001). On multivariate analysis, rich collateralization was associated with hyperlipidemia (P = 0.003) and CCB use (P = 0.028). Independent predictors of poor collaterals were presence of diabetes (P < 0.001), LAD occlusion (P = 0.001) and presentation with acute MI (P = 0.017). CONCLUSION: Diabetes mellitus, occlusion of the LAD and presentation with acute MI are independently associated with poor distal vessel collateralization, whereas hyperlipidemia and use of CCBs are associated with rich collateralization. Factors determining coronary collateral formation may in turn influence outcomes after coronary artery occlusion.     

Prevalence and significance of coronary collateral circulation in patients with acute myocardial infarct

Angiograms from consecutive and unselected patients with acute myocardial infarction were studied with respect to the prevalence as well as the significance of coronary collateral circulation to myocardium distal to the acute coronary occlusion. METHODS: Coronary angiograms were obtained from 700 consecutive and unselected patients with an acute transmural infarction within 3.7 +/- 3 hours (0.5-12) of symptom onset. No patient had undergone i.v. thrombolysis prior to angiography. Complete and acute vessel occlusion was found in 626/700 patients (89%). Coronary collaterals were detected and graded using Rentrop's classification. The grade of collateral circulation was related to the clinical course after 30 days and to the global and regional left ventricular wall motion. RESULTS: Collaterals were found in 334 patients (69%); 242 patients (38%) had collateral flow grade 2 or 3. Collaterals were demonstrated more frequently in women vs men and in patients with multivessel disease. The prevalence of collaterals was unrelated to age and the presence of diabetes mellitus. Patients who had angiography within 3 hours of symptom onset had collaterals detected less frequently than patients who had angiography beyond 6 hours (66% vs 75%, p < 0.05). No collaterals were found in 17/37 patients (47%) in cardiogenic shock and inferior MI but in only 30/164 patients (18%, p < 0.01) without shock. Global and regional left ventricular wall motion after 2 weeks was unrelated to the degree of coronary collateral circulation during acute myocardial infarction. CONCLUSION: Collateral circulation to myocardium distal to an acutely occluded coronary artery is detected in 2/3 patients during the acute infarct phase. The absence of collaterals is related to the early occurrence of cardiogenic shock in patients with inferior MI but not to the presence of diabetes mellitus. After direct angioplasty of the infarct vessel, the protective effects of coronary collaterals on chronic LV function remain uncertain.     

Totally occluded coronary arteries with normal LV function: clinical and angiographic profile

The clinical and coronary angiographic profile of 50 patients (Group I) with total occlusion of one or more major coronary arteries in the absence of electrocardiographic findings of myocardial infarction and normal segmental and global left ventricular (LV) functions were analysed to identify any variables responsible for this observation. Twenty five age and sex matched patients (Group II), who had 100% occlusion of at least one major coronary artery with significant wall motion abnormalities on LV angiograms, served as controls. The mean duration of angina before angiography or the occurrence of acute coronary event was significantly longer in Group I (2.8 +/- 2.2 yrs) compared to Group II (1.2 +/- 1.2 yrs; p less than .05) patients. RCA was found totally occluded more often in Group I as compared to Group II (60% vs 32%; p less than .05) patients, whereas complete occlusion of LAD occurred more frequently in Group II than in Group I (70% vs 32%; p less than .05). Significant stenoses in other arteries was found in 88% of Group I, compared to 48% of Group II patients (p less than .001). Although there was no significant difference in the frequency of collaterals feeding the totally occluded arteries in the two groups, 80% of patients in Group I had grade 3 collaterals compared to only 30% in Group II patients (p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Determinants of collateral development in a canine model with repeated coronary occlusion

Summary It is now accepted that repetitive 2-min coronary occlusion can develop collateral vessels to the area perfused by the occluded coronary artery. However, which factors influence collateral development has yet to be fully elucidated. The goal of the present study was to identify the determinants of the rate of coronary collateral development in dogs undergoing repeated coronary occlusion. The study was conducted in 19 conscious dogs instrumented for measurements of a subendocardial segment length in the area perfused by the left circumflex coronary artery (LCCA), LCCA flow, and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the LCCA. After the recovery from surgery, 2-min LCCA occlusions were conducted eight times daily. Following 141 ± 61 (SD) LCCA occlusions (20 ± 7 days), an LCCA occlusion produced no reduction in segment shortening and negligible reactive hyperemia. The total number of LCCA occlusions needed for adequate collateral development (the rate of collateralization) correlated well with the severity of myocardial ischemia during the first occlusion, which was determined mainly by the extent of postsurgical initial collateral circulation. On the other hand, the response to the ischemic stimulus in the later stage of collateral development was independent of the extent of development of the initial postsurgical collaterals. It is concluded that the overall rate of collateral development is slower in dogs with initially poorer collaterals; however, the response of each dog to the ischemic stimulus in the later stage of collateral development was similar among dogs regardless of the extent of the initial collaterals.Supported by Grants-in-Aid for Scientific Research (B) 63480224 and (C) 63570389 from the Ministry of Education, Science, and Culture, Tokyo, Japan, and grant HL 32800 from the NHLBI, Bethesda, USA.     

Acute myocardial infarction with occlusion of all three main epicardial coronary arteries: when Mother Nature takes care more than physicians

Double-arterial coronary stent thrombosis in acute myocardial infarction (AMI) is an infrequent but severe complication, especially when the third main coronary artery is chronically occluded. The conus artery (CA) can serve as a major source of collateral when the left anterior descendent coronary artery (LAD) becomes obstructed. We report a case of a 48-year-old man presenting with AMI due to a very late double-arterial stent thrombosis (ST) following drug-eluting stent implantation and a chronic occlusion of LAD collateralized by a large anomalous CA, which provided for the entire vascularization of the coronary tree.