Assessment of Left Atrial Work During Acute Coronary Occlusion.

Left atrial (LA) work can be measured through speckle tracking echocardiography by calculating LA pressure-strain loop area, which includes two distinct phases of active contraction/relaxation (A-work) and passive dilation/emptying (V-work). Echocardiographic and hemodynamic data were acquired at baseline and during occlusions of left anterior descending (LAD: n = 7) and left circumflex (LCx: n = 9) coronary arteries in dogs. Left ventricular (LV) circumferential strain was decreased and mean LA pressure was increased in both occlusions. Doppler-derived stroke volume was maintained during LAD occlusion, but it decreased during LCx occlusion. A-work increased during LAD occlusion, but it did not change during LCx occlusion. V-work decreased during LCx occlusion more than during LAD occlusion. The compensatory mechanism of LA function was limited during LCx occlusion, but this occurred during LAD occlusion. This study provided insight into a role of LA function in variable hemodynamic consequences in acute myocardial infarction.

Intravascular Ultrasound-Derived Virtual Fractional Flow Reserve for the Assessment of Myocardial Ischemia.

BACKGROUND: Fractional flow reserve (FFR) is widely used for the assessment of myocardial ischemia. Intravascular ultrasound (IVUS) is an intracoronary imaging method that provides information about lumen and vessel morphology. Previous studies on the expanded use of IVUS to identify functional ischemia have noted an association between anatomy and physiology, but IVUS-derived minimum lumen area (MLA) has a weak-moderate correlation with myocardial ischemia compared with FFR. We developed a method to calculate FFR using IVUS-derived anatomical information for the assessment of myocardial ischemia. The aims of this study were to investigate the relationship between wire-based FFR and IVUS-derived FFR (IVUS-FFR) and to compare the usefulness of IVUS-FFR and IVUS-derived MLA for functional assessment.Methods and Results:We retrospectively analyzed 50 lesions in 48 patients with coronary stenosis who underwent IVUS and FFR simultaneously. IVUS-FFR was calculated using our original algorithm and fluid dynamics. Mean percent diameter stenosis determined on quantitative coronary angiography and on FFR was 56.4±10.7 and 0.69±0.08, respectively. IVUS-FFR had a stronger linear correlation with FFR (R=0.78, P<0.001; root mean square error, 0.057 FFR units) than with IVUS-derived MLA (R=0.43, P=0.002). CONCLUSIONS: IVUS-FFR may be a more valuable method to identify myocardial ischemia, compared with IVUS-derived MLA.

Intracoronary Optical Coherence Tomography-Derived Virtual Fractional Flow Reserve for the Assessment of Coronary Artery Disease.

Fractional flow reserve (FFR) is widely used for the assessment of myocardial ischemia. Optical coherence tomography (OCT) provides accurate visualization of coronary artery morphology. The aim of this study was to investigate the relation between FFR and OCT-derived FFR. We retrospectively analyzed 31 lesions (25 left anterior descending arteries, 2 left circumflex arteries, and 4 right coronary arteries) in 31 patients with moderate-to-severe coronary stenosis, who underwent OCT and FFR measurements simultaneously. OCT-derived FFR was calculated by the original algorithm, which was calculated using the following equation based on fluid dynamics: ΔP = FV + SV2, where V is the flow velocity, F is the coefficient of pressure loss because of viscous friction (Poiseuille resistance), and S is the coefficient of local pressure loss because of abrupt enhancement (flow separation). Mean values of % diameter stenosis by quantitative coronary angiography and FFR were 55.2 ± 14.0% and 0.70 ± 0.14, respectively. OCT-derived FFR showed a stronger linear correlation with FFR measurements (r = 0.89, p <0.001; root mean square error = 0.062 FFR units) than quantitative coronary angiography % diameter stenosis (r = -0.65, p <0.001), OCT measurements of minimum lumen area (r = 0.68, p <0.001), and % area stenosis (r = -0.70, p <0.001). OCT-derived FFR has the potential to become an alternative method for the assessment of functional myocardial ischemia, and may elucidate the relation between coronary morphology and FFR.

Positron emission tomography-computed tomography for imaging of inflammatory cardiovascular diseases.

Inflammation is a determinant of atherosclerotic plaque rupture, the event usually responsible for myocardial infarction and stroke. Possible causes of inflammatory cardiomyopathy include myocarditis, eosinophilic disease, and sarcoidosis. Although conventional imaging techniques can identify the site and severity of luminal stenosis, they do not provide information regarding inflammatory status. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for imaging of inflammatory cardiovascular diseases has been rapidly evolving. Integrated PET/computed tomography (CT) is becoming the method of choice for quantification of arterial inflammation across multiple vessels. Moreover, PET/CT provides information about the activation status of inflammatory cells in the vessel wall, thus allowing early diagnosis and risk stratification of patients. The Japanese health insurance system approved reimbursement for FDG-PET use to detect inflammation sites in cardiac sarcoidosis as of April 2012. This approval has necessitated a more detailed assessment of the clinical value of FDG-PET. Standardized preparation, imaging, and image interpretation protocols should be established to sufficiently suppress physiological FDG uptake in the normal myocardium, and thereby facilitate detection of early-stage cardiac inflammatory lesions with more favorable specificity. This review summarizes the background, clinical utility, state-of-the-art advances, and potential future applications of FDG-PET for imaging inflammatory cardiovascular diseases including cardiac sarcoidosis, large-vessel arteritis, and atherosclerosis.

Qualitative and quantitative assessment of adenosine triphosphate stress whole-heart dynamic myocardial perfusion imaging using 256-slice computed tomography.

BACKGROUND: The aim of this study was to investigate the correlation of the qualitative transmural extent of hypoperfusion areas (HPA) using stress dynamic whole-heart computed tomography perfusion (CTP) imaging by 256-slice CT with CTP-derived myocardial blood flow (MBF) for the estimation of the severity of coronary artery stenosis. METHODS AND RESULTS: Eleven patients underwent adenosine triphosphate (0.16 mg/kg/min, 5 min) stress dynamic CTP by 256-slice CT (coverage: 8 cm, 0.27 s/rotation), and 9 of the 11 patients underwent coronary angiography (CAG). Stress dynamic CTP (whole-heart datasets over 30 consecutive heart beats in systole without spatial and temporal gaps) was acquired with prospective ECG gating (effective radiation dose: 10.4 mSv). The extent of HPAs was visually graded using a 3-point score (normal, subendocardial, transmural). MBF (ml/100g/min) was measured by deconvolution. Differences in MBF (mean ± standard error) according to HPA and CAG results were evaluated. In 27 regions (3 major coronary territories in 9 patients), 11 coronary stenoses (> 50% reduction in diameter) were observed. In 353 myocardial segments, HPA was significantly related to MBF (P < 0.05; normal 295 ± 94; subendocardial 186 ± 67; and transmural 80 ± 53). Coronary territory analysis revealed a significant relationship between coronary stenosis severity and MBF (P < 0.05; non-significant stenosis [< 50%], 284 ± 97; moderate stenosis [50-70%], 184 ± 74; and severe stenosis [> 70%], 119 ± 69). CONCLUSION: The qualitative transmural extent of HPA using stress whole-heart dynamic CTP imaging by 256-slice CT exhibits a good correlation with quantitative CTP-derived MBF and may aid in assessing the hemodynamic significance of coronary artery disease.

Cardiac sarcoidosis diagnosed by histological assessment of a left ventricular apical core excised for insertion of a left ventricular assist device.

A 58-year-old male with no history of heart disease was admitted to hospital for congestive heart failure due to severe left ventricular dysfunction, and clinically diagnosed with dilated cardiomyopathy. He developed recurrent heart failure requiring several admissions to hospital and was finally referred to our institution with severe congestive heart failure. Despite medical treatment with inotropic agents, his symptoms gradually worsened. A left ventricular assist device (LVAD) was implanted together with mitral and tricuspid valve repair at 22 days after hospitalization. A histological assessment of a left ventricular apical core specimen revealed non-caseating granulomas consistent with cardiac sarcoidosis. The postoperative course was uneventful, and he remains under cardiac rehabilitation while waiting for cardiac transplantation.

Usefulness of transthoracic Doppler echocardiography for noninvasive assessment of coronary blood flow in a patient with symptomatic myocardial bridging.

Myocardial bridging (MB) is a congenital anomaly characterized by systolic compression of the tunnelled arterial segment. MB may cause myocardial ischaemia due to abnormal coronary blood flow. We report a case of MB in which transthoracic Doppler echocardiography was used to evaluate the long-term effect of beta-blocker therapy on abnormal coronary blood flow. In this case, beta-blocker therapy with bisoprolol (5.0 mg/day) for 1 month eliminated the patient's symptoms and normalized coronary blood flow through the tunnelled arterial segment.

Peri-infarct dysfunction in post-myocardial infarction: assessment of 3-T tagged and late enhancement MRI.

OBJECTIVE: To determine LV function at different distances from myocardial infarction (MI) by using 3-T tagged MRI and late gadolinium enhancement (LGE). METHODS: Cardiac MR images were acquired from 21 patients with previous MI. The harmonic phase (HARP) method was used to calculate radial and circumferential strain (RS, CS). The two strains were synchronised by subtracting the CS from the RS at the same time, and this was defined as the efficient strain (ES). Peak strain (P-RS, P-CS, P-ES) and time to peak strain (T-RS, T-CS, T-ES) were used as estimates of contractile function. Based on the presence of LGE, myocardium was classified into infarct, border zone, adjacent and remote areas. RESULTS: P-RS and P-ES were significantly greater for remote than for adjacent and infarct areas. P-CS values were significantly greater for remote and border zone than for infarct areas. T-RS and T-ES were significantly shorter for remote and border zone than for infarct areas. T-CS was significantly shorter for border zone than for infarct areas. CONCLUSION: Contractile dysfunction demonstrated by peak strain was correlated with location at different distances from the infarct. In the border zone, contractile deformation was characterised as earlier T-RS, T-CS and T-ES and greater P-CS than in the infarct area.

Assessment of left ventricular wall motion using 16-channel multislice computed tomography: comparison with left ventriculography.

PURPOSE: Using the raw data from coronary computed tomography (CT) angiography, multislice CT (MSCT) can be used to evaluate cardiac function. However, the accuracy of left ventricular (LV) wall motion assessment by MSCT has not been thoroughly investigated. We investigated whether 16-channel MSCT could accurately assess LV wall motion by comparing its results with those of conventional biplane left ventriculography (LVG). MATERIALS AND METHODS: The study included 20 patients with various kinds of heart disease. All patients underwent both contrast-enhanced MSCT and biplane LVG. Using a retrospective electrocardiography-gating technique, 10 phases over one cardiac cycle were extracted. The left ventricle was divided into seven segments according to the American Heart Association classification. Wall motion was scored as follows: 1, normal; 2, mild to moderate hypokinesis; 3, severe hypokinesis; 4, akinesis; 5, dyskinesis; and 6, aneurysm. The scores obtained by MSCT were compared with those obtained by LVG. The wall motion scores were analyzed using the chi-squared independence test (6 x 6 contingency table). RESULTS: Wall motion could be assessed in all segments of the 20 patients using interactive multiplanar animation. Among a total of 140 segments in 20 patients, scores in 118 were concordant between MSCT and LVG (118/140, 84.3%). CONCLUSION: The 16-MSCT can accurately assess LV wall motion.

Assessment of reperfused acute myocardial infarction with two-phase contrast-enhanced helical CT: prediction of left ventricular function and wall thickness.

PURPOSE: To investigate whether two-phase contrast material-enhanced computed tomographic (CT) findings serve as predictors of changes in left ventricular (LV) function and wall thickness (WT) after acute myocardial infarction (MI) and successful angioplasty. MATERIALS AND METHODS: Ethics committee approval and informed consent were obtained. In 58 patients (51 men and seven women; mean age, 62 years +/- 12 [standard deviation]) who had experienced an acute MI and undergone successful angioplasty, two-phase (acquisitions at 45 seconds and 7 minutes) contrast-enhanced CT was performed in the acute (mean interval between treatment and CT, 37 hours +/- 4) and intermediate (mean interval, 28 days +/- 4) periods and for long-term (mean interval, 12 months +/- 4) follow-up. CT images were reviewed for an early perfusion defect (ED) at 45 seconds and for late enhancement (LE) and a residual perfusion defect (RD) at 7 minutes. Myocardial enhancement patterns and WT were assessed, and LV ejection fraction (LVEF) and percentage decrease in WT were calculated. The patient group was subdivided into three groups according to enhancement pattern: Group 1 included patients with LE but no ED or RD; group 2, patients with ED and LE but no RD; and group 3, patients with ED, LE, and RD. Fisher exact testing was used to measure categorical response. Paired and unpaired t tests were used for comparison between two groups (points); Tukey-Kramer multiple comparison and repeated-measures analysis of variance were used for comparisons between the three groups. P < .05 was considered to indicate a significant difference. RESULTS: In group 3 (n = 36), WT in infarcted area was significantly reduced at the intermediate and long-term CT examinations (P < .001). At the intermediate and long-term examinations, percentage decrease in WT was greater in group 2 (n = 10) than in group 1 (n = 12) (P < .05 for intermediate and P < .001 for long-term examination) and was greatest in group 3 (P < .001 for both examinations). LVEF was poorest in group 3 and best in group 1. CONCLUSION: Two-phase contrast-enhanced CT proved useful in predicting LV functional recovery and WT in patients who had experienced acute MI and undergone successful angioplasty.

Impact of multi-detector row computed tomography on the tactics of cardiovascular surgery: from qualitative evaluation to quantitative assessment.

OBJECTIVE: We assessed the role of multi-detector row computed tomography in cardiovascular surgery. METHODS: The efficacy of multi-detector row computed tomography was assessed concerning the graft patency of coronary artery bypass, arterial atheromatous degeneration, small vessel imaging, and left ventricular volume measurement. Images were reconstructed using both the volume-rendering and the maximum-intensity-profile methods. Arterial atherosclerotic degeneration was assessed by aortic wall volume and aortic calcification volume. RESULTS: In the assessment of bypass graft patency, multi-detector row computed tomography showed a 98% correct positive ratio with sensitivity and specificity of 98% and 100%, respectively. Atheromatous degeneration showed matching results in more than 70% of cases compared with intraoperative findings. More than 92% of arterial branches with diameters of 3 mm or greater were detected by preoperative multi-detector row computed tomography images, though only 6% of branches with diameters of 2 mm or less could be visualized. There was a positive linear correlation between left ventricular volumes determined by multi-detector row computed tomography and those calculated from cine angiography. CONCLUSION: Multi-detector row computed tomography clearly visualized coronary bypass grafts and aortic arterial branches, providing detailed vascular images. Atheromatous degeneration assessed by multi-detector row computed tomography was equivalent with intraoperative findings in more than 70% of cases. Left ventricular volumes measured by multi-detector row computed tomography correlated closely with those determined by cine-angiography. Multi-detector row computed tomography is an efficient and promising modality in cardiovascular surgery.

Computed tomography assessment of myocardial perfusion, viability, and function.

In addition to coronary artery assessment, contrast-enhanced multidetector spiral computed tomography (CE-MDCT) can provide valuable information about myocardial perfusion. Using CE-MDCT, myocardial perfusion defects are often observed in the early phase of the contrast bolus (early defect (ED)), with residual defects (RDs) and late enhancement (LE) observed in the late phase in myocardial infarction (MI). However, the clinical significance of EDs, RDs, and LE has not yet been fully described. This work reviews myocardial viability and function by CE-MDCT based on our prior data by including contrast-enhanced single-slice (detector) CT (CE-SSCT) and CE-MDCT. Recently, equivalent results were obtained, as seen in CE-SSCT with images by CE-MDCT. In this review, images that were acquired by MDCT will be presented. In this work, the following items will be the focus: myocardial enhancement patterns (EDs, LE, and RDs), early perfusion defects and their relationship to wall thickness (WT) and wall motion, early CT perfusion defects vs. Tl-201 single photon emission CT (SPECT), the protocol for performing dual-phase contrast CT, classification of enhancement patterns, enhancement patterns on dual-phase CE-MDCT vs. left ventricular functional recovery and WT, changes in enhancement patterns in conjunction with healing stage, enhancement patterns on dual-phase CE-MDCT vs. 201Tl/99mTc-pyrophosphate (dual-isotope SPECT), the clinical meaning of each enhancement pattern, pitfalls of enhancement patterns and other diseases, and study limitations and the future of MDCT.