Distribution Of Myocardial Perfusion Research Articles

Comparative study of myocardial perfusion and coronary flow velocity reserve derived from adenosine triphosphate stress myocardial contrast echocardiography in coronary lesions with no/mild stenosis

BackgroundQualitative myocardial perfusion (QMP) derived from myocardial contrast echocardiography reflects the capillary flow, while coronary flow velocity reserve from Doppler spectrum (D-CFVR) of the left anterior descending coronary artery (LAD) is used to assess coronary microvascular function, particularly after excluding severe epicardial coronary stenosis. The present study aimed to assess the relationship of QMP and D-CFVR in detecting coronary microvascular disease (CMVD) by using adenosine triphosphate stress myocardial contrast echocardiography (ATP stress MCE).Methods and resultsSeventy-two patients (mean age: 54.22 ± 12.78 years) with chest pain and <50% coronary stenosis diagnosed by quantitative coronary angiography or dual-source CT underwent ATP stress MCE. The distribution of myocardial perfusion and CFVR value was estimated by experienced physicians. Of the 72 LAD with 0%–50% diameter stenosis, 15 (21%) exhibited abnormal CFVR and 31 (43%) displayed abnormal perfusion with ATP stress MCE. Eleven of the 15 LAD territories (73%) with abnormal CFVR values showed abnormal perfusion. However, CFVR was considered normal in 20 LAD territories (35%), despite the presence of perfusion defect in the territory.ConclusionAbnormal myocardial perfusion during ATP stress MCE was found in a sizable percentage of patients in whom CFVR of the supplying vessel was considered normal.

Myocardial perfusion and flow reserve in the asynchronous heart: mechanistic insight from a computational model.

The tight coupling between myocardial oxygen demand and supply has been recognized for decades, but it remains controversial whether this coupling persists under asynchronous activation, such as during left bundle branch block (LBBB). Furthermore, it is unclear whether the amount of local cardiac wall growth, following longer lasting asynchronous activation, can explain differences in myocardial perfusion distribution between subjects. For better understanding of these matters, we built upon our existing modeling framework for cardiac mechanics-to-perfusion coupling by incorporating coronary autoregulation. Regional coronary flow was regulated with a vasodilator signal based on regional demand, as estimated from regional fiber stress-strain area. Volume of left ventricular wall segments was adapted with chronic asynchronous activation towards a homogeneous distribution of myocardial oxygen demand per tissue weight. Modeling results show that: (1) both myocardial oxygen demand and supply are decreased in early-activated regions and increased in late-activated regions; (2) but that regional hyperemic flow remains unaffected; while (3) regional myocardial flow reserve (the ratio of hyperemic to resting myocardial flow) decreases with increases in absolute regional myocardial oxygen demand as well as with decreases in wall thickness. These findings suggest that septal hypoperfusion in LBBB represents an autoregulatory response to reduced myocardial oxygen demand. Furthermore, oxygen demand-driven remodeling of wall mass can explain asymmetric hypertrophy and the related homogenization of myocardial perfusion and flow reserve. Finally, the inconsistent observations of myocardial perfusion distribution can primarily be explained by the degree of dyssynchrony, the degree of asymmetric hypertrophy, as well as the imaging modality used.

Changes in myocardial perfusion according to left ventricular pacing site in cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): 1. The Danish Heart Foundation 2. The Health Research Fund of the Central Denmark Region Background/Introduction Changes in left ventricular (LV) myocardial perfusion according to LV pacing site during cardiac resynchronization therapy (CRT) has only been sparsely described. Purpose To assess changes in LV global and regional myocardial perfusion according to LV pacing site after six months CRT. Methods Data from patients enrolled in the randomized controlled trial "Electrically vs. Imaging-guided Left Ventricular Lead Placement in Cardiac Resynchronization Therapy" was evaluated. Global and segmental absolute myocardial perfusion in ml/g/min was assessed by 82Rb-PET the day before CRT implantation and at six-months follow-up (6MFU). The exact LV pacing site was determined by post-implant cardiac CT. Perfusion and pacing site were evaluated using the standard 17’-segment LV model. Echocardiographic assessment of LV ejection fraction (EF) was performed the day before CRT implantation and at 6MFU. Results 93 patients (age 71±9 years; ischemic heart disease 48%; female 25%; median QRS 166±20 ms; mean LVEF 30±7%; NYHA class I/II/III/IV (%) 0/63/33/3) were included. Distribution of LV pacing sites is shown in Figure 1. No change in LV global perfusion was observed from baseline to 6MFU (0.79 to 0.81 ml/g/min, P=0.41; respectively). LV EF increased by 9±10%. Baseline global perfusion was higher in the 39 patients in whom LV EF had increased ≥10% at 6MFU (0.86 vs. 0.74 ml/g/min, P=0.02; respectively). However, no difference in perfusion-change was observed between patients with ≥10% increase in LV EF at 6MFU and patients with <10% increase (0.01 vs. 0.02 ml/g/min, P=0.76; respectively). Baseline perfusion was higher in the segments chosen for LV-pacing than in the non-paced segments (0.96 vs. 0.78 ml/g/min, P=0.00; respectively). Perfusion in the paced segments dropped to 0.86 ml/g/min (P=0.00) at 6MFU. Perfusion in the neighbouring segments also dropped during six months (from 0.91 to 0.86 ml/g/min, P=0.03), while perfusion in the non-paced and non-neighbouring segments increased (from 0.75 to 0.80 ml/g/min, P=0.01). Conclusion Despite a mean increase in LV EF of 9%, global myocardial perfusion remained unchanged. CRT resulted in a homogenous distribution of myocardial perfusion with a decreased perfusion in segments concordant and adjacent to LV pacing site and a corresponding increased perfusion in remote segments.

Differences in attenuation pattern in myocardial SPECT between CZT and conventional gamma cameras

BackgroundIn myocardial perfusion imaging (MPI), single-photon emission tomography (SPECT) soft-tissue attenuation by the abdomen, breasts, and lateral chest wall may create artifacts that mimic true perfusion defects. This may cause misdiagnosis of myocardial perfusion. The aim of the present study was to compare the localization, extent, and depth of attenuation artifacts in MPI SPECT for a multi-pinhole cadmium zinc telluride (CZT) camera vs a conventional gamma camera. MethodsPhantom and patient measurements were performed using a CZT camera (GE NM 530c) and a conventional gamma camera (GE Ventri). All images were attenuation corrected with externally acquired low-dose computed tomography. The localization, extent, and depth of the attenuation artifact were quantified by comparing attenuation-corrected and non-attenuation-corrected images. ResultsAttenuation artifacts were shifted from the inferolateral wall to the lateral wall using the CZT camera compared to a conventional camera in both the patient and the phantom. The extent of the attenuation artifact was significantly larger for the CZT camera compared to the conventional camera (23 ± 5% vs 15 ± 5%, P < .001) for patients and the result was similar for the phantom (28% vs 19%). Furthermore, the depth of the attenuation artifact (percent of maximum counts) was less pronounced for the CZT camera than for the conventional camera, both for phantom measurements (73% vs 67%) and patients (72 ± 3% vs 68 ± 4%, P < .001). ConclusionsAttenuation artifacts are found in different locations to different extents and depths when using a CZT camera vs a conventional gamma camera for MPI SPECT. This should be taken into consideration when evaluating MPI SPECT studies to avoid misinterpretation of myocardial perfusion distribution.

Impact of iterative reconstruction with resolution recovery in myocardial perfusion SPECT: phantom and clinical studies

The corrections of photon attenuation, scatter, and depth-dependent blurring improve image quality in myocardial perfusion single-photon emission computed tomography (SPECT) imaging; however, the combined corrections induce artifacts. Here, we present the single correction method of depth-dependent blurring and its impact for myocardial perfusion distribution in phantom and clinical studies. The phantom and clinical patient images were acquired with two conditions: circular and noncircular orbits of gamma cameras yielded constant and variable depth-dependent blurring, respectively. An iterative reconstruction with the correction method of depth-dependent was used to reconstruct the phantom and clinical patient images. We found that the single correction method improved the robustness of phantom images whether the images contained constant or variable depth-dependent blurring. The myocardial perfusion databases generated from 72 normal patients exhibited uniform perfusion distribution of whole myocardium. In summary, the single correction method of depth-dependent blurring with iterative reconstruction is helpful for myocardial perfusion SPECT.

Creation and characterization of normal myocardial perfusion imaging databases using the IQ·SPECT system

BackgroundImage acquisition by short-time single-photon emission-computed tomography (SPECT) has been made feasible by IQ·SPECT. The aim of this study was to generate normal databases (NDBs) of thallium-201 (201Tl) myocardial perfusion imaging for IQ·SPECT, and characterize myocardial perfusion distribution. Methods and resultsWe retrospectively enrolled 159 patients with a low likelihood of cardiac diseases from four hospitals in Japan. All patients underwent short-time 201Tl myocardial perfusion IQ·SPECT with or without attenuation and scatter correction (ACSC) in either supine or prone position. The mean myocardial counts were calculated using 17-segment polar maps. Three NDBs were derived from supine and prone images as well as supine images with ACSC. Differences between the supine and prone positions were observed in the uncorrected sex-segregated NDBs in the mid-inferolateral counts (p ≤ 0.016 for males and p ≤ 0.002 for females). Differences between IQ·SPECT and conventional SPECT were also observed in the mid-anterior, inferolateral, and apical lateral counts (p ≤ 0.009 for males and p ≤ 0.003 for females). Apical low counts attributed to myocardial thinning were observed in the apical anterior and apex segments in the supine IQ·SPECT NDB with ACSC. ConclusionsThere were significant differences between uncorrected supine and prone NDBs, between uncorrected supine NDB and supine NDB with ACSC, and between uncorrected supine NDB and conventional SPECT NDB. Understanding the pattern of normal distribution in IQ-SPECT short-time acquisitions with and without ACSC will be helpful for interpretation of imaging findings in patients with coronary artery disease (CAD) or low likelihood of CAD and the NDBs will aid in quantitative analysis.

Fully quantitative cardiovascular magnetic resonance myocardial perfusion ready for clinical use: a comparison between cardiovascular magnetic resonance imaging and positron emission tomography

BackgroundRecent studies have shown that quantification of myocardial perfusion (MP) at stress and myocardial perfusion reserve (MPR) offer additional diagnostic and prognostic information compared to qualitative and semi-quantitative assessment of myocardial perfusion distribution in patients with coronary artery disease (CAD). Technical advancements have enabled fully automatic quantification of MP using cardiovascular magnetic resonance (CMR) to be performed in-line in a clinical workflow. The aim of this study was to validate the use of the automated CMR perfusion mapping technique for quantification of MP using 13N–NH3 cardiac positron emission tomography (PET) as the reference method.MethodsTwenty-one patients with stable CAD were included in the study. All patients underwent adenosine stress and rest perfusion imaging with 13N–NH3 PET and a dual sequence, single contrast bolus CMR on the same day. Global and regional MP were quantified both at stress and rest using PET and CMR.ResultsThere was good agreement between global MP quantified by PET and CMR both at stress (−0.1 ± 0.5 ml/min/g) and at rest (0 ± 0.2 ml/min/g) with a strong correlation (r = 0.92, p < 0.001; y = 0.94× + 0.14). Furthermore, there was strong correlation between CMR and PET with regards to regional MP (r = 0.83, p < 0.001; y = 0.87× + 0.26) with a good agreement (−0.1 ± 0.6 ml/min/g). There was also a significant correlation between CMR and PET with regard to global and regional MPR (r = 0.69, p = 0.001 and r = 0.57, p < 0.001, respectively).ConclusionsThere is good agreement between MP quantified by 13N–NH3 PET and dual sequence, single contrast bolus CMR in patients with stable CAD. Thus, CMR is viable in clinical practice for quantification of MP.

Early Changes in Myocardial Microcirculation in Asymptomatic Hypercholesterolemic Subjects: As Detected by Perfusion CT

Intramyocardial microvessels show functional changes in early stages of atherosclerosis prior to epicardial coronary artery stenosis. However, clinical CT does not have adequate spatial resolution to resolve the microvessels. To clinically detect changes in the function of the intramyocardial microcirculation, the spatial heterogeneity of the distribution of myocardial perfusion (F) and intramyocardial microcirculatory blood volume (Bv) was determined by perfusion CT. Two human subject groups were studied: (i) a "Control" group (24) with no risk factors nor evidence of coronary artery disease (CAD), and (ii) an "At-Risk" group (24) with hypercholesterolemia, but no evidence of CAD. In the perfusion CT image, a region of interest (ROI) covering the left ventricular myocardium was subdivided into multiple nested ROI (nROI) of equal size and used to compute F and Bv for each nROI. No significant differences between the groups were demonstrable in overall myocardial F, or Bv. The nROI data showed significantly increased spatial heterogeneity in the "At Risk" group when compared to "Control" subjects. This study demonstrates that subresolution distribution at the microcirculatory level can be quantified with myocardial perfusion CT and significant changes in these parameters occur in hypercholesterolemic subjects before they have developed significant changes in conventional perfusion parameters.

Myocardial perfusion distribution and coronary arterial pressure and flow signals: clinical relevance in relation to multiscale modeling, a review

Coronary artery disease, CAD, is associated with both narrowing of the epicardial coronary arteries and microvascular disease, thereby limiting coronary flow and myocardial perfusion. CAD accounts for almost 2 million deaths within the European Union on an annual basis. In this paper, we review the physiological and pathophysiological processes underlying clinical decision making in coronary disease as well as the models for interpretation of the underlying physiological mechanisms. Presently, clinical decision making is based on non-invasive magnetic resonance imaging, MRI, of myocardial perfusion and invasive coronary hemodynamic measurements of coronary pressure and Doppler flow velocity signals obtained during catheterization. Within the euHeart project, several innovations have been developed and applied to improve diagnosis-based understanding of the underlying biophysical processes. Specifically, MRI perfusion data interpretation has been advanced by the gradientogram, a novel graphical representation of the spatiotemporal myocardial perfusion gradient. For hemodynamic data, functional indices of coronary stenosis severity that do not depend on maximal vasodilation are proposed and the Valsalva maneuver for indicating the extravascular resistance component of the coronary circulation has been introduced. Complementary to these advances, model innovation has been directed to the porous elastic model coupled to a one-dimensional model of the epicardial arteries. The importance of model development is related to the integration of information from different modalities, which in isolation often result in conflicting treatment recommendations.

Quantitative analysis of transmural gradients in myocardial perfusion magnetic resonance images

Conventional quantitative assessments of myocardial perfusion analyze the temporal relation between the arterial input function and the myocardial signal intensity curves, thereby neglecting the important spatial relation between the myocardial signal intensity curves. The new method presented in this article enables characterization of sub-endocardial to sub-epicardial gradients in myocardial perfusion based on a two dimensional, "gradientogram" representation, which displays the evolution of the transmural gradient in myocardial contrast uptake over time in all circumferential positions of the acquired images. Moreover, based on segmentation in these gradientograms, several new measurements that characterize transmural myocardial perfusion distribution over time are defined. In application to clinical image data, the new two-dimensional representations, as well as the newly defined measurements revealed a clear distinction between normal perfusion and inducible ischaemia. Thus, the new measurements may serve as diagnostic markers for the detection and characterization of epicardial coronary and microvascular disease.

A Method for Reconstructing the Arterial Input Function during Helical CT: Implications for Myocardial Perfusion Distribution Imaging

To determine if a multidetector computed tomographic (CT) image acquisition and analysis method can enable accurate measurement of the arterial input function (AIF) during first-pass adenosine stress helical multidetector CT angiography and to test the effect of using this method on the semiquantitative assessment of myocardial perfusion distribution. The animal care and use committee of Johns Hopkins University approved the use of all procedures. The AIF was reconstructed by using a combination of bolus-tracking and time-registered helical multidetector CT data. After the AIF reconstruction method was validated in healthy animals, coronary stenosis was induced in seven dogs and contrast material-enhanced multidetector CT was performed during adenosine infusion (0.14-0.21 mg per kilogram of body weight per minute). Myocardial attenuation density (AD) parameters normalized to portions of the AIF were compared with microsphere myocardial blood flow (MBF) measurements at linear regression analysis. There was no significant difference between the area under the curve (AUC) for dynamic multidetector CT-derived AIF (3108 + or - 1250 [standard deviation]) and that for combined bolus-tracking and time-registered multidetector helical CT-derived AIF (3086 + or - 941) (P = .90). When AIF analysis was applied to helical multidetector CT myocardial perfusion measurements, the correlation between MBF and mean myocardial AD normalized to the AUC for the entire AIF was significant (R(2) = 0.82, P <.001). Myocardial AD normalized to the AUC for the AIF measured during helical multidetector CT correlated best with MBF (R(2) = 0.86, P <.001). The combination of bolus tracking and time-registered helical imaging enables reconstruction of the AIF during multidetector CT perfusion imaging. The helical CT AIF can be used to improve the semiquantitative assessment of myocardial perfusion distribution.

Organization and collateralization of a subendocardial plexus in end-stage human heart failure

In the failing myocardium a subendocardial plexus can develop. Detection of the presence or function, however, of such a plexus does not form part of the present diagnostic spectrum for heart failure. This may now change as new methods for high-resolution imaging of myocardial perfusion distribution are being developed. A severely hypertrophic heart was harvested during transplantation and analyzed for morphology of the intramural coronary arterial vasculature. The heart only had one coronary ostium, and the main branches of the coronary artery were cannulated. A fluorescent casting material was infused that was allowed to harden under physiological pressure. The entire heart was frozen and placed in a novel imaging cryomicrotome and sequentially cut in 25-microm slices. High-resolution images of each cutting plane were acquired, allowing a detailed three-dimensional reconstruction of the arterial vasculature. The epicardial layer of the free wall demonstrated a normal vasculature with penetrating branching arteries. The endocardial layer and the septum revealed a highly interconnected vascular plexus with large vessels oriented parallel to the apicobasal axis. An extensive endocardial network with collaterals was detected, forming connections between the main epicardial branches. We conclude that an outward remodeling of transmural vessels did not prevent the generation and growth of subendocardial conduit arteries. The orientation and vascular volume in the plexus provides an opportunity for detection by novel techniques of MRI contrast imaging currently developed. Knowledge of the effect on perfusion studies is required to prevent a misinterpretation of subendocardial perfusion images in heart failure.

Attenuation correction of myocardial SPECT by scatter-photopeak window method in normal subjects

Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) method can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusion database. A total of 32 sets of exercise-rest myocardial images with Tc-99 m-sestamibi were acquired in both photopeak (140 keV +/- 10%) and scatter (7% of lower side of the photopeak window) energy windows. Myocardial perfusion databases by the SSPAC method and non-AC (NC) were created from 15 female and 17 male subjects with low likelihood of cardiac disease using quantitative perfusion SPECT software. Segmental myocardial counts of a 17-segment model from these databases were compared on the basis of paired t test. AC average myocardial perfusion count was significantly higher than that in NC in the septal and inferior regions (P < 0.02). On the contrary, AC average count was significantly lower in the anterolateral and apical regions (P < 0.01). Coefficient variation of the AC count in the mid, apical and apex regions was lower than that of NC. The SSPAC method can improve average myocardial perfusion uptake in the septal and inferior regions and provide uniform distribution of myocardial perfusion. The SSPAC method could be a practical method of attenuation correction without X-ray CT.

15.34: Effect of reconstruction parameters and acquisition times on myocardial perfusion distribution in normals

15.34: Effect of reconstruction parameters and acquisition times on myocardial perfusion distribution in normals

Model prediction of subendocardial perfusion in the presence of an epicardial coronary artery stenosis

Objective: With coronary disease the subendocardium is most vulnerable to ischemia which will occur when Diastolic Time Fraction (DTF) is to short and/or coronary pressure (Pc) to low. Since recent clinical techniques permit measurement of subendocardial perfusion our objective is to predict the effects of hemodynamic conditions on the induction of ischemia.Methods: Using data from microsphere experiments a layered model of the myocardial wall was developed in which each layer is represented by a hyperemic resistance and autoregulatory resistance in series. Myocardial perfusion distribution during hyperemia was predicted for different degrees of coronary stenosis, at different levels of DTF.Results: A reference DTF was chosen (corresponding to HR=90) at which perfusion was rather evenly distributed at normal Pc = 90 mmHg. At this reference condition the effect of the stenosis on perfusion distribution was homogenous. However, at shorter or longer DTF, the subendocardium was the first or last to suffer from shortage of perfusion, the maginitude of which depended on stenosis degree.Conclusions: For larger values of DTF as normal for patients with medication and with the applied pharmacological stress tests the possible occurrence of subendocardial ischemia at physical exercise is underestimated.

Model prediction of subendocardial perfusion of the coronary circulation in the presence of an epicardial coronary artery stenosis

The subendocardium is most vulnerable to ischemia, which is ameliorated by relaxation during diastole and increased coronary pressure. Recent clinical techniques permit the measuring of subendocardial perfusion and it is therefore important to gain insight into how measurements depend on perfusion conditions of the heart. Using data from microsphere experiments a layered model of the myocardial wall was developed. Myocardial perfusion distribution during hyperemia was predicted for different degrees of coronary stenosis and at different levels of Diastolic Time Fraction (DTF). At the reference DTF, perfusion was rather evenly distributed over the layers and the effect of the stenosis was homogenous. However, at shorter or longer DTF, the subendocardium was the first or last to suffer from shortage of perfusion. It is therefore concluded that the possible occurrence of subendocardial ischemia at exercise is underestimated when heart rate is increased and DTF is lower.

Effects of Right, Left, and Biventricular Pacing on Myocardial Perfusion in Ischemic Conditions

In normal hearts, the distribution of regional myocardial perfusion is altered by ventricular pacing. Little is known about the impact of ventricular pacing on regional myocardial perfusion in ischemic conditions. In this acute echocardiographic study, we compared the respective effects of right ventricular pacing (RVP), left ventricular pacing (LVP), and biventricular pacing (BVP) on regional perfusion in a swine model of graded ischemia. Ventricular pacing leads were placed at the apex of the right ventricle and on the lateral wall of the left ventricle in nine open-chest pigs. Myocardial contrast echocardiography was successively performed during spontaneous rhythm (SR), RVP, LVP, and BVP in random order at baseline and during three stages of incremental ischemia (left anterior descending + circumflex). At baseline, RVP decreased myocardial perfusion of the septal and inferior walls compared to SR (P < 0.05), whereas LVP decreased perfusion of the lateral wall (P < 0.05). No significant differences were observed in regional perfusion during BVP compared to SR. In ischemic conditions, RVP worsened myocardial perfusion in the ischemic anterior wall as well as in the septal and inferior walls (P < 0.05), whereas both LVP and BVP did not alter perfusion in the ischemic area compared to SR. Compared to baseline, in ischemic conditions, RVP has a more pronounced detrimental impact on perfusion abnormalities. In contrast, BVP induced a significant improvement in local myocardial perfusion. Therefore, BVP could be preferred to RVP in patients with ischemic cardiomyopathy.

Heterogeneity of Myocardial Perfusion in Distal Coronary Embolism with Different Particle Sizes

We hypothesized that altered myocardial perfusion distribution patterns could be seen with coronary distal emboli of different particle sizes using myocardial contrast echocardiography. In 16 open-chest anesthetized dogs, microsphere suspensions of 9 or 500 microm in diameter were injected into the left anterior descending coronary artery until the mean left anterior descending coronary artery flow rate was reduced to less than 30% of baseline flow. During baseline conditions and after maximal embolization, real-time myocardial contrast echocardiography was performed by intravenous infusion of an echocontrast agent. In animals infused with 9-microm microspheres, a transmural perfusion defect was seen at the time of maximal embolization. In contrast, in animals infused with 500-microm microspheres, a subendocardial perfusion defect was observed. The particle size of coronary distal emboli affects myocardial perfusion distribution.

Transmural distribution of myocardial blood perfusion and phasic coronary blood flow pattern in a canine model of acute ischemia

Background Although several investigators have analyzed coronary artery blood flow under various conditions, almost all these studies have measured only some branches of the left anterior descending (LAD), left circumflex (LCX), or right coronary (RCA) artery. Methods In a canine model of acute ischemia ( n = 5), we simultaneously assessed (a) regional myocardial blood perfusion using microspheres and (b) phasic coronary blood flow patterns as measured by three epicardial flow probes placed around the LAD, LCX, and RCA. Results The results from this study indicated that the LAD supplies blood to the epicardial ( r = 0.687, p < 0.0001), midwall ( r = 0.556, p = 0.0021), and endocardial layers ( r = 0.666, p = 0.0001) of the LAD area; the LCX supplies the midwall ( r = 0.514, p = 0.0051) and endocardial layer ( r = 0.621, p = 0.0004) of the LCX area, antero-lateral papillary muscle ( r = 0.548, p = 0.0025), and postero-medial papillary muscle ( r = 0.641, p = 0.0002), especially during the diastolic phase; and the RCA supplies the right ventricular apex ( r = 0.559, p = 0.0020), left atrium ( r = 0.618, p = 0.0005), right atrium ( r = 0.471, p = 0.0114), and postero-medial papillary muscle ( r = 0.486, p = 0.0088), especially during the systolic phase. Conclusions These results are potentially relevant to understanding the physiology of myocardial blood perfusion and to improving treatment of acute myocardial ischemia and infarction.

Evaluation of Transmural Myocardial Perfusion by Ultra-Harmonic Myocardial Contrast Echocardiography in Reperfused Acute Myocardial Infarction

The transmural distribution of myocardial perfusion is important for predicting the contractile reverse of an infarcted wall in reperfused acute myocardial infarction (AMI). Evaluating transmural myocardial perfusion by myocardial contrast echocardiography (MCE) could predict the long-term recovery of left ventricular (LV) function. The study group comprised 20 consecutive patients with a first-episode anterior AMI with total occlusion of the proximal left anterior descending artery, who underwent successful percutaneous coronary intervention within 24 h of onset. MCE was performed on the 15th day after the onset, using ultraharmonic gray-scale imaging with intermittent end-systolic triggering every 4 beats or every 6 beats. Regions of interest were placed over both the endocardial and epicardial region at the mid-septal level. Regional wall motion (RWM) of the infarcted anterior wall and global LV function were assessed by 2-dimensional echocardiography and left ventriculography in both the acute and chronic phase. The transmural distribution of myocardial perfusion by MCE demonstrated a significant relation with RWM score index (r = 0.75, p = 0.0004). Recovery of RWM and LV ejection fraction (LVEF) at 6 months after reperfusion was significantly greater in the group with good perfusion of the epicardium according to MCE than in the poor perfusion group [RWM (SD/cord); -1.23+/-0.91 vs -3.51+/-0.84, p = 0.001, LVEF (%); 63.8+/-10.4 vs 47.0+/-3.4, p = 0.04]. Assessing the transmural distribution of myocardial perfusion by MCE can predict the long-term recovery of LV function after a reperfused AMI.