Acute myocardial infarction in a young woman with normal coronary arteries and myocardial bridging

Myocardial bridging (MB) is defined as an intramural segment of a coronary artery that normally courses epicardially. MB is usually a benign condition; however, some cases resulting in myocardial ischaemia, infarction and sudden death have been reported. We describe a case of myocardial infarction related to MB in a young healthy woman with no risk factors for coronary artery disease. The bridge was demonstrated in detail by coronary CT angiography using multiplanar reconstruction and three-dimensional volume-rendered techniques.     

The effect of angiotensin-II during ventriculography in dogs with normal coronary arteries.

Left ventriculography was performed with and without angiotensin-II in dogs with normal coronary arteries. Concomitant administration of angiotensin significantly attenuated the myocardial depression associated with ventriculography. The beneficial effect of angiotensin may be due to its ability to maintain aortic diastolic pressure and thus flush the contrast material from the myocardium more rapidly, at least in animals without imposed coronary stenosis.     

Reduced myocardial flow reserve in anatomically normal coronary arteries due to elevated baseline myocardial blood flow in men with old myocardial infarction

BACKGROUND: Decreased myocardial flow reserve (MFR) in angiographically normal coronary arteries in patients with old myocardial infarction (OMI) has been reported. METHODS AND RESULTS: To clarify factors for the reduced MFR in OMI and to compare them with those in angina pectoris (AP), baseline myocardial blood flow (MBF) and MBF during dipyridamole administration were measured with nitrogen 13 ammonia positron emission tomography, after which MFR was calculated for 13 men with AP, 18 men with OMI, and 15 age-matched male control subjects. MFR was compared among the 3 groups in segments perfused by nonstenotic arteries. Baseline MBF in patients with OMI was significantly higher than that in patients with AP and control subjects. MBF during dipyridamole administration in patients with OMI was significantly lower than that in control subjects. MFR in patients with AP was 2.50 +/- 0.91 (P <.05 vs control subjects [3.47 +/- 1.25]), and that in patients with OMI was 1.83 +/- 0.61 (P <.01 vs control and AP groups). Ejection fraction (EF) in patients with OMI was significantly decreased compared with that in patients with AP. However, there was no significant difference in the mean score of the individual risk factors between patients with AP and those with OMI. In the pooled data with AP and OMI, baseline MBF and EF were significant for the reduced MFR. CONCLUSIONS: MFR and EF in patients with OMI were significantly decreased compared with those in patients with AP. Increased baseline MBF and decreased EF were significant factors for the reduced MFR in patients with AP and OMI.     

Quantitative thallium-201 myocardial exercise scintigraphy in normal subjects and patients with normal coronary arteries

Quantitative thallium-201 myocardial exercise scintigraphy was tested in two patient populations representing alternative standards for cardiac normality: group I comprised 18 male uncatheterized patients with a low likelihood of coronary artery disease (CAD); group II contained 41 patients with normal coronary arteriograms. Group I patients were younger, they achieved a higher rate-pressure product than group II patients; all had normal findings by physical examination and electrocardiography at rest and exercise. Group II patients comprised 21 females, 11 patients showed abnormal electrocardiography at rest, and five patients showed ischemic ST depression during exercise. Twelve patients had signs of minimal CAD. Twelve patients revealed abnormal visual and quantitative thallium findings, three of these patients had minimal CAD. Profiles of uptake and washout of thallium-201 were derived from both patient groups, and compared with normal limits developed by Maddahi et al. Furthermore, low likelihood and angiographically normal patients may differ substantially, and both sets of normal patients should be considered when establishing criteria for abnormality in exercise thallium imaging. When commercial software containing normal limits for quantitative analysis of exercise thallium-201 imaging is used in clinical practice, it is mandatory to compare these with normal limits of uptake and washout of thallium-201, derived from the less heterogeneous group of low-likelihood subjects, which should be used in selecting a normal population to define normality.     

Gallbladder infarction following hepatic transcatheter arterial embolization. Angiographic study

Gallbladder infarction developing after transcatheter arterial embolization (TAE) in patients with malignant hepatic tumors was studied by comparing preoperative angiographic and postoperative macroscopic and histological findings. Eight patients demonstrated occlusion of the cystic artery or its branches by embolic materials on post-TAE angiograms. Surgery revealed infarction of the gallbladder in 6 patients; no infarction was noted in the other 2, although branches of the cystic artery were occluded on the post-TAE angiogram. Due to recanalization of the occluded artery, the infarcted area could be assessed only by follow-up angiography. No patient experienced perforation of the gallbladder as a result of infarction. The authors suggest that patients with post-TAE infarction of the gallbladder can be treated conservatively if they are kept under close observation.     

Cesium-129 myocardial scintigraphy to quantify myocardial infarction in dogs.

The sizes of surgically induced acute myocardial infarctions were quantified in a study of 28 dogs. Four projections (right and left anterior oblique, anterior, and left lateral) were obtained with 129Cs myocardial scintigraphy. Control images, taken before surgery, were compared with images taken 24-72 hr after coronary artery ligation. From postmortem examination the size of the infarct was determined and expressed as a percentage of the total left ventricle. On a standard diagram four independent observers marked the infarcted areas in each projection, expressed the severity of involvement in each area, and determined overall infarction size as a percentage of the total left ventricle. A nonlinear least-squares method was also employed to derive the size of the infarct, using the results from each observer's diagram. There were positive correlations between each observer's percentage estimate and the autopsy results. The overall accuracy of the least-squares method was similar to that of the individual observers. In this study, Observer 3 proved that acute myocardial infarcts can be quantified accurately from multiple scintigraphic projections of the myocardium, but the other three observers had difficulty in estimating infarct size. This difficulty probably resulted from the lack of well-validated criteria to aid the observer in determining the area of infarction, the severity of involvement within that area, or the total size of a myocardial infarct. Improvement in these estimates will require the development of definitive criteria, the use of optical scanners or computer processing, and combinations of radionuclides.     

Imaging of post-traumatic cardiac rhabdomyolysis with normal coronary arteries

Numerous cases of acute myocardial infarction (AMI) have been reported in the literature following closed chest injuries, due to post-traumatic dissection or thrombosis of a coronary artery. In the follow-up of AMI, wall thickness during diastole and systole provides important information on heart viability. Multidetector computed tomography (MDCT) is currently the only noninvasive instrumental investigation which provides an appreciable assessment of the coronary arteries, as well as heart wall thickness measurements. We describe and discuss the clinical and imaging findings, especially of MDCT, in a case of post-traumatic regional myocardial necrosis with normal coronary arteries.     

Three-dimensional fusion of coronary arteries with myocardial perfusion distributions: clinical validation.

Clinical decisions regarding diagnosis and effective treatment of coronary artery disease frequently require integration of information from various imaging modalities, which are acquired, processed, and read at different physical locations and times. We have developed methods to integrate the information in 2 cardiac imaging studies, perfusion SPECT and coronary angiography. Three-dimensional (3D) models of the coronary artery tree created from biplane angiograms were automatically aligned with 3D models of the left ventricular epicardial surface created from perfusion SPECT. Myocardial mass at risk was used as a unique measure to validate the accuracy of the unification. METHODS: Thirty patients were injected with the perfusion agent (99m)Tc-tetrosfosmin during balloon occlusion while undergoing percutaneous transluminal coronary angioplasty for single-vessel coronary artery disease. Thus, a single, severe perfusion defect was induced by a single coronary artery occlusion of known severity and placement. The accuracy of the unification was measured by computing the overlap between physiologic area at risk, determined using SPECT perfusion quantification techniques only, and anatomic area at risk, determined using coronary artery anatomy aligned with the epicardial surface of the left ventricle. RESULTS: The unification resulted in an 80% overlap of areas at risk, and an overlap of 84% of normal areas, for all coronary artery distributions. The mass at risk measured based on the unified anatomic information correlated with the physiologically based mass at risk as y = 0.92x + 10.3 g; r = 0.76, SEE = 10.4 g. CONCLUSION: A unification algorithm for automatically registering 3D models of the epicardial surface from perfusion SPECT and 3D coronary artery trees from coronary angiography has been presented and validated in 30 patient studies.     

"False-positive" myocardial perfusion scintigraphy findings in patients with angiographically normal coronary arteries: insights from intravascular sonography studies.

Abnormal exercise perfusion findings have been described as false-positive for coronary artery disease in patients with suspected angina and angiographically normal coronary arteries. METHODS: The significance of this finding was further investigated by obtaining intravascular sonograms and Doppler guidewire measurements of at least 2 coronary arteries in 20 consecutive patients who had chest pain, normal coronary angiography findings, and positive stress-rest sestamibi SPECT findings. The summed reversible score was used to describe the extent and severity of reversible perfusion defects. On the basis of scintigraphy findings, vessels were grouped as supplying underperfused myocardial segments (target vessels, n = 20) or normal territories (reference vessels, n = 25). The presence and extension of atherosclerotic disease of the epicardial arteries were assessed by intracoronary sonography. Measurements of plaque area (PA), vessel area (VA), and relative cross-sectional PA (RPA) (RPA = PA/VA) were obtained at the site of maximum plaque concentration. The coronary flow velocity reserve (CFR) was assessed during adenosine-induced hyperemia, and the relative flow reserve was calculated as the target-to-reference coronary reserve ratio. RESULTS: The median summed reversible score was 3 (range, 1-6). Intracoronary sonography showed occult atherosclerosis in 19 patients (95%), with RPA greater than 40% in 16 patients (80%). Mean RPA was significantly greater in the target vessels (46% +/- 14%) than in reference vessels (12% +/- 18%; P < 0.0001). Doppler flow velocity measurements showed abnormal vasodilation capacity (CFR < 2.5) in 14 patients (70%). Mean CFR was significantly lower in the target vessels than in the reference vessels (2.3 +/- 0.5 versus 3.1 +/- 0.6; P < 0.0001). A significant inverse correlation was seen between the summed reversible score and the coronary reserve ratio (y = 9.05x - 9.9; r = 0.70; P < 0.005). CONCLUSION: Reversible perfusion defects seen on SPECT images are often associated with angiographically unrecognized occult atherosclerotic changes and an abnormal vasodilation capacity of the coronary circulation. The tendency to dismiss abnormal exercise perfusion findings as false-positive in these patients may be unjustified.     

Multicompartmental analysis of late contrast enhancement in areas of myocardial infarction supplied by chronically occluded coronary arteries

Purpose

To analyze the relationship between late contrast enhancement (LCE) and the interstitial distribution volume (V_In) of gadolinium (Gd) tracers in the myocardial infarction (MI) areas supplied by chronically occluded arteries from patients. In animal experimental models, LCE has already been shown to correspond to an enhanced V_In of Gd tracers and thus, to a decrease in the amount of intact cells.

Materials and Methods

A multicompartmental analysis was applied to serial MRI images encompassing both infarct and remote areas and recorded with a conventional two‐dimensional (2D) segmented inversion‐recovery gradient‐echo (IR‐GRE) sequence during a 15‐minute period following Gd‐diethylenetriamine pentaacetic acid (Gd‐DTPA) injection in 12 patients with Q‐wave MI supplied by chronically occluded coronary arteries.

Results

V_In from infarct tissue was: 1) higher than V_In from remote areas (in % of myocardial volume: 74 ± 16% vs. 20 ± 7%, P < 0.001); and 2) correlated with the quantification of LCE between infarct and noninfarct areas at the 15th minute (R² = 0.63, P = 0.002). However, the difference in V_In between infarct and remote myocardium was a much better correlate of this quantified LCE (R² = 0.85, P < 0.001).

Conclusion

Detection of LCE in the MI territories supplied by chronically occluded arteries relates to the difference in the V_In of tracers between the infarct and the noninfarct areas. J. Magn. Reson. Imaging 2009;29:78–85. © 2008 Wiley‐Liss, Inc.