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PubMed1999

Reperfusion accelerates the distribution of type I and III collagen messenger RNA expression after acute myocardial infarction: in situ hybridization in experimental infarction in rats.

BACKGROUND: The effects of reperfusion on the time-dependent appearance and distribution of type I and III collagen messenger RNA (mRNA) expression had not hitherto been examined. OBJECTIVE: To compare the sequential changes in the extent of distribution of type I and III collagen mRNA expression in reperfused infarct hearts of rats with those in unreperfused infarct hearts. METHODS: Using an experimental rat model of infarction, we examined type I and III collagen mRNA expression with specific rat pro alpha 1 (I) and human pro alpha 1 (III) collagen riboprobes by in-situ hybridization. Reperfusion was established after a 2 h coronary ligation that produced complete necrosis of the myocytes. RESULTS: Positive signals both for alpha 1 (I) and for alpha 1 (III) collagen mRNA appeared in the infarct peripheral zone 12 h after coronary ligation both of the reperfused and of unreperfused hearts. The spread of signal into the infarct central zone occurred 1-2 days earlier for the reperfused hearts than it did for the unreperfused hearts. The difference between the distributions of signals for the reperfused and unreperfused hearts became obscure on day 14. No notable difference between the extents of signal distribution for alpha 1 (I) and alpha 1 (III) collagen mRNA was obtained. We observed intense signals from spindle-shaped mesenchymal cells (myofibroblasts and fibroblasts) located between surviving myocytes in the marginal zone of the infarct. No myocyte exhibited signals both for alpha 1 (I) and for alpha 1 (III) collagen mRNA. CONCLUSION: In the present study, using in-situ hybridization, we demonstrated that reperfusion accelerates the distribution of expression both of alpha 1 (I) and of alpha 1 (III) collagen mRNA in the infarct zone after acute myocardial infarction in rats.

Animals↗
PubMed1992

[Quantitative assessment of the infarct size with the unfolded map method of 201Tl myocardial SPECT in patient with acute myocardial infarction].

The unfolded map method of 201Tl single photon emission computed tomography (SPECT) was evaluated as to the ability to quantify and the clinical reliability in estimation of infarct size. At first, the following results were obtained in basic experiments using thoracic phantom: 1) the defect area estimated by the unfolded map method was well correlated with the real defect area in spite of overestimation of the defect area, when the defect area was determined by an isocount method (below 80% of maximum count) (y = 1.941 + 2.29x, r = 0.971, p less than 0.001); 2) the defect volume estimated by short-axis images of 201Tl SPECT was closely correlated with real defect volume in spite of overestimation of defect volume (y = 0.762 + 2.156x, r = 0.982, p less than 0.001); 3) when the defect area was estimated by division of the defect volume by the mean myocardial compartment thickness, it was closely correlated with real defect area (y = 0.946 + 1.232x, r = 0.990, p less than 0.001); 4) when the volume was calculated from the summation of voxels in the regions districted by isocount threshold level at each section of the 99mTc SPECT, the optimal isocount threshold level (percentage to maximum count) was 55%. In addition, the clinical reliability of the unfolded map method as infarct sizing was evaluated in 26 patients with acute myocardial infarction by comparing it with enzymatic method, Bull's eye method, and 99mTc pyrophosphate (PYP) SPECT method. In 14 first attack cases of patient without right ventricular infarction, infarct area (IA) of the unfolded map method correlated most closely with the accumulated creatine kinase MB isoenzyme release (CK-MBr) (r = 0.897), compared with the extent score (ES) (r = 0.853) and the severity score (SS) (r = 0.871) of Bull's eye method and the infarct volume (IV) (r = 0.595) of 99mTc PYP SPECT. In conclusion, although the unfolded map method of 201Tl SPECT has the tendency which overestimate infarct size, it is accurate and clinically reliable method in estimating infarct size.

Adult↗
PubMedDate not supplied

[Echocardiographic evaluation of asynergy of the left ventricle in the early stages of acute myocardial infarct and its value in predicting infarct complications].

The authors report on their experience with the semiquantitative echocardiographic evaluation of left ventricular asynergy (group of 36 patients examined by two-dimensional echocardiography, dividing the left ventricle into 20 segments) in the early stage of myocardial infarction and its application in the prediction of complications of infarction. The authors evaluated asynegry using two parameters: RA (range of asynergy and IA (asynergy index) which characterizes the grade of ventricular affection. They describe the calculation of these parameters. The authors revealed a significant correlation (p less than 0.005) between RA or IA and the incidence of decompensation or cardiogenic shock. RA and IA values (median values and scatter) in three groups of patients (non-complicated infarction, complicated infarction and infarction with cardiogenic shock and death) give the opportunity of early stratification of patients with acute infarction. RA above 50% and IA above 20 indicate that the patients is at high risk. On the other hand, RA lower than 25% and IA lower than 5 suggest a minor infarction and probably an uncomplicated course of the disease. In the investigated group anterior infarctions affected a greater mass of the left ventricle than diaphragmatic ones and the higher death rate in this group (20% vs. 14%) was consistent with this.

Adult↗
PubMed1988

[Ultrastructure of cardiomyocytes in the peri-infarct zone during the treatment of experimental myocardial infarct in rats using the hexapeptide dalargin].

The experiments on white rats with induced myocardial infarction have studied the influence of dalargin on the infarction size and peri-infarction zone ultrastructure. 24 hours later the decrease in the infarction zone size was detected in rats who had received dalargin in a dose of 50 and 100 micrograms/kg. In the peri-infarction zone the increase in glycogen quantity, the lower degree of lipid infiltration, the increase in mitochondrial number and mitochondrial energy effectiveness coefficient were noted, as compared to control animals. Sarcolemma of cardiomyocytes from the peri-infarction zone in rats on dalargin was impermeable for colloidal lanthanum. The decrease in the infarction size under the effect of dalargin is explained by its influence on the survival of cardiomyocytes in the peri-infarction zone.

Animals↗
PubMedDate not supplied

[Biographical analysis and myocardial infarct: a study of myocardial infarction patients and 2 reference groups].

In a retrospective case-referent study, 105 male myocardial infarction patients (age: 35-69), 105 hospital referents, and 105 neighbourhood referents, all of the same age, were interviewed with respect to exposure to some psychosocial risk indicators in their lives. These indicators include: Type A coronary-prone behavior pattern; the prevalence of stressful changes in childhood and adolescence, work and career, and family and social life; the syndrome of vital exhaustion and depression, which may precede myocardial infarction. The central question of this study is in what manner and in what connection these risk indicators may affect the lives of myocardial infarction patients. The results indicate that in general the prevalence of Type A behavior is twice as high in myocardial infarction patients as in both referent groups. On the other hand, this difference only reaches significance in younger patients (N = 30; age: 35-44). The prevalence of stressful life changes in myocardial infarction patients is characterized in particular by both the cohort-specific and the "non-normative" nature of these life changes. In young patients (N = 15; age: 35-39), all of whom but one are Type A, only some life changes associated with work and career occur significantly more often. In older patients (N = 30; age: 50-54, and 65-69) the latter problems are replaced by and intermingled with (chronic) conflicts in family and social life, that occur significantly more often. The myocardial infarction patients score significantly higher on the syndrome of vital exhaustion and depression than both referent groups. This syndrome is probably specific to myocardial infarction patients, and appears-unlike Type A behavior-not to be dependent on age. The results are discussed in terms of an "attributional" model that might explain the development of vital exhaustion and depression in the biography of myocardial infarction patients.

Adult↗
PubMedDate not supplied

Improvement in contractility of infarct zone after dobutamine infusion predicts good (TIMI II or III) flow in infarct related artery.

Eighteen patients of 'Q' wave acute myocardial infarction (AMI) (age 50 +/- 6.2 years), underwent dobutamine stress echocardiography (DSE) before hospital discharge (7.2 +/- 1.3 days after AMI) to find out the correlation between response of infarct zone to dobutamine infusion and TIMI grade flow in infarct related artery (IRA). The aim of study was to test the hypothesis that infarct zone which shows improvement in contractility after dobutamine infusion has viable myocardial tissue and would have good flow (TIMI II or III) in IRA. Echocardiographically, improvement in contractility in the centre of infarct zone by at least 1 grade (on a scale of 4) was termed as positive response on DSE. The mean dose of dobutamine was 19.4 micrograms/kg/min. Ten patients had positive response on DSE; 8 of them had good antegrade flow in IRA. Eight patients had no improvement in contractility of infarct zone on DSE; 6 of them had poor flow in IRA. Clinical markers of reperfusion (relief of chest pain, early ST settlement, peak CPK-MB levels), age of patient, site of AMI, time to thrombolysis, resting left ventricular ejection fraction, wall motion score of the infarct zone and presence of collaterals were not significantly different in patients with good or poor flow in IRA. Thus, improvement in contractility of infarct zone after dobutamine infusion can predict good flow (TIMI II or III) in IRA with 80 percent sensitivity, 75 percent specificity, 80 percent diagnostic accuracy, 80 percent positive predictive value and 75 percent negative predictive value.

Adult↗
PubMed1997

Long-term prognosis of patency of infarct-related coronary artery after thrombolytic treatment in acute myocardial infarction. Collaborative Research Group on Thrombolysis.

OBJECTIVE: To investigate the long-term prognostic influence of patency of the infarct-related coronary artery. METHODS: One thousand two hundred and sixty seven cases of acute myocardial infarction with thrombolytic treatment between July 1991 and January 1995 in 36 collaborative hospitals were followed-up after discharge with a total follow-up rate of 84.5%. Patency of infarct-related coronary artery was assessed by uniform clinical criteria. Eight hundred and forty three patients with patency were followed up for 16.0 +/- 10.4 months and 424 patients without patency for 19.2 +/- 12.22. Death or up to the end of March, 1995 was used as the end point. RESULTS: Comparisons of patients with patent versus nonpatent infarct-related coronary artery during follow-up showed: (1) Cardiac death rate was 2.85% in patients with patency while 4.72% in those without patency (logrank test, P > 0.1). (2) Three-year survival rates calculated by Kaplan-Meier curve were 91.6% and 73.9% respectively (logrank test, P < 0.001). (3) Incidence of reinfarction were 5.7% and 5.9% respectively (P < 0.05). (4) Patients with class III-IV NYHA cardiac function occurred in 11.3% and 17.9% respectively (P < 0.01). (5) By Cox regression model analysis patency of infarct-related coronary artery, recurrent infarction, age and infarct sites were independent prognostic factors. Survival probability increased by 33.5% in patients with patency compared to those without patency. CONCLUSION: It is evident that patency of infarct-related coronary artery could improve long-term survival.

Adult↗
PubMed1997

Assessment of Regional Viability in the Infarct Zone Following Myocardial Infarction.

The goal of reperfusion strategies in patients with acute myocardial infarction is to salvage myocardium within the infarct zone at risk from the acute occlusion. The status of wall motion and thickening within the infarct zone is an imprecise guide to the extent of salvage and viability within the infarct zone, based on the well-described phenomenon of myocardial stunning. However, knowledge of significant salvage and preserved viability within an infarct zone soon after infarction has important implications regarding clinical decision making for catheterization and potential revascularization: given preserved viability, restoration of normal coronary flow in the setting of a severe residual stenosis or occlusion would be expected to result in significant recovery of regional, and possibly global left ventricular function, with attendant implications for prognosis and outcome.This review will critically explore imaging techniques regarding their ability to discern myocardial viability within the infarct zone soon after myocardial infarction, including electrocardiography, angiography, echocardiography, and radionuclide studies of myocardial perfusion, metabolism and cell membrane integrity.

Journal Article↗
PubMed2001

Magnetic resonance characterization of the peri-infarction zone of reperfused myocardial infarction with necrosis-specific and extracellular nonspecific contrast media.

BACKGROUND: Because ischemically injured myocardium is frequently composed of viable and nonviable portions, a method to discriminate the two is useful for clinical management. METHODS AND RESULTS: Ischemically injured myocardium was characterized with extracellular nonspecific (Gd-DTPA) and necrosis-specific (mesoporphyrin) MR contrast media in rats. Relaxation rates (R1) were measured on day 1 and day 2 by inversion-recovery echoplanar imaging. Spin-echo imaging was used to define contrast-enhanced regions and regional wall thickening. Gadolinium concentration, area at risk, and infarct size were measured at postmortem examination. DeltaR1 ratio (DeltaR1(myocardium)/DeltaR1(blood)) after administration of Gd-DTPA was greater in ischemically injured myocardium (1.20+/-0.15) than in normal myocardium (0.47+/-0.05, P<0.05), which was attributed to differences in gadolinium concentration and water content. The Gd-DTPA-enhanced region on day 2 was larger (32.8+/-0.9%) than true infarction as demonstrated by triphenyltetrazolium chloride (TTC) (24.6+/-1.4%, P<0.001, r=0.21). Bland-Altman analysis revealed that the Gd-DTPA-enhanced region overestimated true infarct size by 7.8+/-5.9%. On the other hand, the mesoporphyrin-enhanced region (26.9+/-1.8%, P=NS, r=0.87) and true infarct size were identical. The difference in the areas demarcated by the 2 agents is the peri-infarction. Systolic and diastolic MR images revealed no wall thickening in the mesoporphyrin-enhanced region (0.3+/-3.3%) but reduced thickening in the Gd-DTPA-enhanced rim (8.5+/-5.5%, P<0.05). CONCLUSIONS: The Gd-DTPA-enhanced region encompasses both viable and nonviable portions of the ischemically injured myocardium. The Gd-DTPA-enhanced area overestimated infarct size, but the mesoporphyrin-enhanced area matched true infarct size. The salvageable peri-infarction zone can be characterized with double-contrast-enhanced and functional MR imaging; the mismatched area of enhancement between the 2 agents shows residual wall thickening.

Animals↗
PubMed1995

[Difference in MRI findings and risk factors between multiple infarction without dementia and multi-infarct dementia].

MRI findings and risk factors for vascular dementia were evaluated with multi-variate analysis in 96 multi-infarct patients without dementia and 40 multi-infarct patients with dementia (MID). Only subjects with small infarcts in the territory of the perforator artery or deep white matter were studied. The diagnosis of MID was diagnosed according to DMS-III criteria and Hachinski's ischemia score. Location and area of patchy high-intensity areas including small infarcts, the degree of periventricular high intensity (PVH), and the degree of brain atrophy were examined with MR images. Independent variables were: history of hypertension, diabetes mellitus, other complications; systolic and diastolic blood pressure, atherosclerotic index, hematocrit, history of smoking, level of education, and activities of daily life (ADL). Hayashi's quantification method II was used to analyze the data. The most significant correlation was found between history of hypertension and dementia (partial correlation coefficient: 0.39). Significant correlations were also found between ADL and dementia (0.32), between thalamic infarction and dementia (0.31), and between PVH and dementia (0.27). Age, brain atrophy index, and history of diabetes mellitus contributed little to dementia. The contribution to dementia did not differ significantly between right and left patchy high-intensity areas on MR images. Location of infarcts, except for bilateral thalamic infarcts and large PVH, contributed little to dementia. Thus it would be difficult to base a prediction of the prevalence of vascular dementia on MRI findings. However, both hypertension and ADL contribute to vascular dementia and both are treatable, which may be significant for the prevention of dementia.

Aged↗
PubMed1989

Risk factors for the complication of cerebral infarction in Japanese patients with acute myocardial infarction.

The incidence and risk factors for cerebral infarction in Japanese patients with acute myocardial infarction were evaluated. Seven (5.0%) of 140 patients with acute myocardial infarction suffered from cerebral infarction during their initial hospitalization. The incidence was slightly higher than those reported in Western countries. Anterior wall myocardial infarction and a past history of cerebrovascular disease were considered to be probable risk factors for the complication. A beneficial effect of anticoagulant therapy in preventing cerebral infarction in cases of acute myocardial infarction with those risk factors is suggested.

Aged↗
PubMed2003

[Multiple small subcortical infarction required to distinguish from lacunar infarction: evaluation by use of diffusion-weighted imaging].

Lacunar infarctions are small lesions caused by occlusion of the deep and penetrating vessels. Occlusion of such vessels are resulted from thrombosis based on atherosclerotic change. However, we occasionally encounter a patient with lacunar infarction seemed to be caused by embolic mechanism, as who has had previous experience of TIA or presented with clinical symptoms suddenly. Diffusion-weighted imaging (DWI) has high accuracy for depicting small ischemic lesions and discrimination of recent infarctions from old ones. We studied frequency, risk factors and stroke mechanism in the territory of penetrating arteries detected on DWI, and sensitivity of ischemic lesions by DWI as compared with conventional MRI images. Fifty-three consecutive patients with lacunar infarction in the territory of penetrating arteries who admitted to our hospital and were studied by DWI within 24 hours. Nine (17.0%) of 53 patients had multiple high signal lesions on DWI. These lesions were found in single arterial territory in 4 patients and in more than 2 territories in 5 patients. It was presumed that stroke mechanisms were artery to artery or cardiogenic embolism. DWI revealed all 38 hyperintensity lesions, while conventional MRI revealed 35 lesions, although the latter was resulted from retrospectively referring to the DWI finding. Therefore, conventional MRI alone might have been difficult to detect multiple lesions. DWI was enable to distinguish embolic infarction from small vessel lacunar infarction, leading to feasible patient management. Therefore, DWI should be performed in all patients with lacunar infarction, even if neurological finding is correspondent with the conventional MRI finding.

Aged↗
PubMed1993

Role of quantitative planar thallium-201 imaging for determining viability in patients with acute myocardial infarction and a totally occluded infarct-related artery.

We studied 57 patients with a recent infarction and an occluded infarct-related artery to test the hypothesis that the amount of 201Tl on delayed planar images correlates with the extent of viable myocardium after acute myocardial infarction. There was a significant (p < 0.001) correlation between mean 201Tl activity in the infarct zone and regional wall motion score in that zone both at baseline (r = -0.60, n = 57) and 1 mo after attempted angioplasty (r = -0.67, n = 48), with better function being associated with greater 201Tl uptake in the delayed images. There was no correlation between the number of segments showing redistribution and the wall motion score. We conclude that in patients with recent myocardial infarction and an occluded infarct-related artery, the average 201Tl activity within the infarct zone on delayed planar imaging correlates well with the extent of viable myocardium in that zone. The presence or absence of redistribution does not influence these results.

Adult↗
PubMed1980

Echoventriculography in acute myocardial infarction. IV. Infarct size and reliability by pathologic anatomic correlations.

A morphologic-echocardiographic comparison was carried out in 24 consecutive patients to determine the accuracy of multidirectional single-beam echocardiography in imaging the size and site of 22 fatal acute myocardial infarctions and of 2 postinfarction ventricular aneurysms treated surgically. Echocardiography never missed the infarction, regardless of whether the infarction was anterior or posterior. The correlation between the echocardiographic and pathologic anatomic extent of infarct, as expressed by a percentage of the left ventricular horizontal circumference, was r=0.88 (p less than 0.001). One hundred four of one hundred eleven infarcted segments (94%) were detected by echo; only the posterior septal and the most lateral segments of the left ventricle tended to remain out of range of the method. The regional asynergy at the center of the infarcted region was clearcut-systolic thickening was never seen and the systolic wall motion was paradoxical in 75% of the patients (mean, -20+/-2.0 mm). Analysis of the regional function from multiple sites characterized reduction of the left ventricular performance (p less than 0.0005) better than did the ejection fraction in the presence of asynergy. An old postinfarction scar was differentiated from the acute necrosis. Thus, segmental left ventricular akinesis or paradoxical motion as seen by multidirectional echocardiography permits noninvasively a reliable estimation of the extent of acute myocardial infarction.

Adult↗
PubMed2006

Infarcted intraductal papilloma of the breast: cytologic features with stage of infarction.

Fine-needle aspiration cytology (FNAC) is being employed with increasing frequency for the pre-operative diagnostic workup of breast lesions. Although most cases show morphologic features very characteristic of specific entities, rare lesions with infarcted breast can cause problems in interpretation. We present cytologic findings in seven cases of an infarcted intraductal papilloma of the breast (IDPB) that was diagnosed by FNAC, and we also report the correlation of cytological features and stages of infarcted IDPB. In the early stage of infarction, numerous degenerative cells and necrotic debris were demonstrated. Isolated degenerative cells showed columnar, spindle, polygonal and fiber-like cells, with coagulated and smudged nuclei. Ghost cells were also seen. Extensive necrosis was demonstrated with a few sheets of ductal cells in the mid-stage of infarction. In the late stage of infarction, clusters of fibroblasts, ductal cells and necrotic debris were found. Knowledge of the characteristic cytologic pattern in different stages of infarcted IDPB may be helpful to suggest the probable pre-operative diagnosis of those lesions. Familiarity with this entity is important in preventing misdiagnosis of malignancy.

Adult↗
PubMed2006

Quantitative myocardial infarction on delayed enhancement MRI. Part I: Animal validation of an automated feature analysis and combined thresholding infarct sizing algorithm.

PURPOSE: To develop a computer algorithm to measure myocardial infarct size in gadolinium-enhanced magnetic resonance (MR) imaging and to validate this method using a canine histopathological reference. MATERIALS AND METHODS: Delayed enhancement MR was performed in 11 dogs with myocardial infarction (MI) determined by triphenyltetrazolium chloride (TTC). Infarct size on in vivo and ex vivo images was measured by a computer algorithm based on automated feature analysis and combined thresholding (FACT). For comparison, infarct size by human manual contouring and simple intensity thresholding (based on two standard deviation [2SD] and full width at half maximum [FWHM]) were studied. RESULTS: Both in vivo and ex vivo MR infarct size measured by the FACT algorithm correlated well with TTC (R = 0.95-0.97) and showed no significant bias on Bland Altman analysis (P = not significant). Despite similar correlations (R = 0.91-0.97), human manual contouring overestimated in vivo MR infarct size by 5.4% of the left ventricular (LV) area (equivalent to 55.1% of the MI area) vs. TTC (P < 0.001). Infarct size measured by simple intensity thresholdings was less accurate than the proposed algorithm (P < 0.001 and P = 0.007). CONCLUSION: The FACT algorithm accurately measured MI size on delayed enhancement MR imaging in vivo and ex vivo. The FACT algorithm was also more accurate than human manual contouring and simple intensity thresholding approaches.

Algorithms↗
PubMed2004

Simultaneous assessment of left-ventricular infarction size, function and tissue viability in a murine model of myocardial infarction by cardiac manganese-enhanced magnetic resonance imaging (MEMRI).

Owing to its signal-enhancing characteristics in viable well-perfused tissue, divalent manganese (Mn2+) has been used as a myocardial imaging contrast agent. Because Mn2+ can enter excitable cells through the voltage-gated L-type calcium channels, manganese-enhanced MRI (MEMRI) has been used to determine the viability and the inotropic state of the heart. In this study, we examined the correlation between left ventricular infarction zone as assessed by cardiac MEMRI and function in mice with permanent coronary artery occlusion. At an Mn2+ infusion dose of 1.72+/-0.47 nmol/min/g body weight, the steady-state signal intensity (SI) enhancement 20-26 min post-Mn2+ infusion of the normal septum and left-ventricular wall during diastole was 128.2+/-14.4 and 127.9+/-26.5%, respectively, whereas the infarction zone was 56.0+/-7.1%. During systole, the SI enhancement was 144.6+/-33.0, 116.0+/-18.7 and 48.3+/-20.0% for the normal septum, left-ventricular wall and infarction zone, respectively. A good correlation was obtained between the MEMRI determined infarction volume and conventional histological TTC staining (r = 0.9582, p<0.01). There was also a strong negative correlation between MEMRI determined infarction percentage (compared with whole left ventricle) and ejection fraction (r = -0.94, p<0.05). These data suggest that the Mn2+ concentration at steady state in the heart may reflect altered tissue viability in the infarcted tissue as well as surrounding region following myocardial infarction. In conclusion, in vivo cardiac MEMRI offers a manner in which functional, pathologic and viability data may be obtained simultaneously in myocardial tissue.

Animals↗
PubMed1997

Regionally different vascular response to vasoactive substances in the remodelled infarcted rat heart; aberrant vasculature in the infarct scar.

Remodelling after myocardial infarction (MI) is associated with vascular adaption, increasing vascular capacity of non-infarcted myocardium, and angiogenesis in the infarcted part during wound healing and scarring. We investigated regional vascular reactivity in the infarcted rat heart. Transmural infarction of the left ventricular free wall was induced by coronary artery ligation. After 3 weeks, regional flow during maximal vasodilation (nitroprusside, NPR) and submaximal vasoconstriction (arginine-vasopressin, AVP) were studied in buffer-perfused hearts. The main findings were: (1) a reduced vasodilator response (NPR) in the viable part of the left ventricular free wall, where hypertrophy was most pronounced, resulting in reduced maximal tissue perfusion of the myocardium bordering the scar (19.7 + 0.6 v 25.7 + 1.2 ml/min.g), whereas perfusion of other non-infarcted regions was preserved. (2) A 54% lower vasodilator response (NPR) and a 25% stronger vasoconstriction (AVP) in scar tissue compared to viable parts of MI hearts. Microscopy showed thicker walls of resistance arteries in scar tissue than in viable parts of MI hearts or in sham hearts, morphometrically substantiated by two- to three-fold greater wall/lumen ratios. These data indicate a deviant response of scar vessels of MI hearts, and in the non-infarcted part, a reduced coronary reserve in the most hypertrophied region. Whereas the former may be caused by different vessel structure, the reduced vasodilator reserve of the spared part of the left ventricular free wall may indicate vasodilation at rest due to insufficient vascular growth. Thus, the most hypertrophied region would be at the highest risk of further ischemic damage.

Animals↗