Perfusion Territories Of Coronary Arteries Research Articles

285 BIVENTRICULAR TAKO-TSUBOSYNDROME ASSOCIATED WITH SYNCOPE AND UNCONSCIOUSNESS

Abstract A 58-years old woman came to the emergency department due to syncope; she had been found lying on the ground in her residence. At the admission the patient was unconscious but had preserved blood pressure 120/80 mmHg. CT brain scan was negative for hemorrhage. Admission ECG showed a 52 b/m sinus bradycardia, elevated antero-septal ST segment and prolonged QT interval. Diagnosis of antero-septal STEMI was made and a coronary angiogram performed via right femoral access showed mild atheromasia in the absence of angiographically significant lesions. Bedside echocardiogram showed severe left ventricular dysfunction (LVEF 35%) with akinesia of apical and mid-ventricular segments. The right ventricle presented a marked hypocontractility of the apical region and a preserved kinetics of the basal portion (TAPSE 22 mm). There was also a moderate mitral regurgitation and a mild tricuspid regurgitation with a sPAP of 50 mmHg (40+10). On blood sampling, high-sensitivity troponin was slightly elevated (3950 pg/ml) and marked hyponatriemia (117 mmol/l) and slight hypokalemia (3.1 mmol/l) were noted. The echocardiogram on the third day showed an improvement in global and segmental kinetics of left ventricle with an estimated EF of 45% and persistence of a mild hypocontractility of the apex of right ventricle. During her hospital stay, her cognitive state gradually improved and she remained asymptomatic without evidence of arrhythmic events on monitoring. The ECG evolved on days with normalization of the ST-T tract, negative T wave in the anterior region and prolonged QTc interval. The pre-discharge echocardiogram showed a recovery of biventricular kinetics with an estimated EF of 50%. The presence of a transient abnormality in biventricular wall motion beyond a single epicardial coronary artery perfusion territory with new electrocardiographic change met the diagnostic criteria of Tako-tsubo Syndrome defined by Mayo Clinic criteria. The electrocardiogram on the day of discharge showed a 55 b/m sinus bradycardia with a negative T wave from V1 to V4. Tako-tsubo syndrome (TTS) is an acute and reversible left ventricular dysfunction that improves spontaneously within days or weeks and is often preceded by emotional or physical stress. Biventricular involvement in TTS is typically identified on imaging studies such as echocardiography and MRI. TTS with RV involvement is associated with a higher rate of in-hospital mortality and long-term adverse clinical events than isolated LV TTS. In our clinical case, biventricular involvement was associated with a severe clinical presentation (syncope and unconsciousness). This case shows that biventricular Tako-tsubo is a clinical scenario that requires intensive care monitoring and strict cardiological evaluation.

Adding Speckle-Tracking Echocardiography to Visual Assessment of Systolic Wall Motion Abnormalities Improves the Detection of Myocardial Infarction

The aim of this study was to investigate whether speckle-tracking echocardiography (STE) improves the detection of myocardial infarction (MI) over visual assessment of systolic wall motion abnormalities (SWMAs) using delayed enhancement cardiac magnetic resonance imaging as a reference. Transthoracic echocardiography was performed in 95 patients with first ST segment elevation MI 110days (interquartile range, 97-171days) after MI and in 48 healthy control subjects. Two experienced observers independently assessed SWMAs. Separately, longitudinal peak negative, peak systolic, end-systolic, global strain, and strain rate were measured and averaged for the American Heart Association-recommended coronary artery perfusion territories. Receiver operating characteristic analysis was used to determine a single optimal cutoff value for each strain parameter. The diagnostic accuracy of an algorithm combining visual assessment and STE was evaluated. Median infarct size and transmurality were 15% (interquartile range, 7%-24%) and 64% (interquartile range, 46%-78%), respectively. Sensitivity, specificity, and accuracy of visual assessment to detect MI were 74% (95% CI, 63%-82%), 85% (95% CI, 72%-93%), and 78% (95% CI, 70%-84%), respectively. Among the strain parameters, SR had the highest diagnostic accuracy (area under the curve, 0.88; 95% CI, 0.83-0.94; cutoff value, -0.97sec-1). The combination with STE improved sensitivity compared with visual assessment alone (94%; 95% CI, 86%-97%; P<.001), minimally affecting specificity (79%; 95% CI, 65%-89%; P=.607). Overall accuracy improved to 89% (95% CI, 82%-93%; P=.011). Multivariate analysis accounting for age and sex demonstrated that SR was independently associated with MI (odds ratio, 2.0; 95% CI, 1.6-2.7). The sensitivity and diagnostic accuracy of visually detecting chronic MI by assessing SWMAs are moderate but substantially improve when adding STE.

Late gadolinium enhancement on CMR and sustained ventricular tachycardia predict severe cardiac infl ammation

Objective Early diagnosis of severe inflammatory forms of non-ischaemic cardiomyopathy (NICM), e.g. cardiac sarcoidosis (CS) or giant cell myocarditis (GCM), may enable unique treatment. However, there is limited information on how to identify CS or GCM in unselected patients with suspected NICM. We studied the clinical and imaging predictors of severe cardiac inflammation at the era of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR).Methods and results In this observational cohort study, we enrolled 86 consecutive patients referred for LGE-CMR due to suspected NICM. Patients were extensively examined for underlying aetiology and followed up for at least two years to assure the final diagnosis. Ischaemic cardiomyopathy was excluded. During follow-up, 11 (13%) patients were diagnosed with CS (n = 8) or GCM (n = 3). At baseline, sustained ventricular tachycardia (OR = 20.8, P= 0.001) and the volume of left ventricular LGE (OR = 1.06 for each 1% increase in LGE, P= 0.001) were significant adjusted predictors of CS or GCM. Palpitation, a disease course less than 3 months, septal abnormality in echocardiography, reduced stroke volume and atrioventricular block were other unadjusted predictors of CS or GCM. Multifocal LGE, affecting several myocardial layers and not confined to coronary artery perfusion territories, was useful in identifying CS or GCM, with 52-fold unadjusted OR (P <0.001), sensitivity of 91% and specificity of 84%. In addition, positron emission tomography detected mediastinal lymph node biopsy targets in CS.Conclusions In consecutive patients suspected for NICM, LGE volume and sustained ventricular tachycardia predict independently CS or GCM. Multifocal LGE is useful in identifying severe cardiac inflammation.

Characterization of innate collateral connections in the canine heart

BackgroundInnate coronary collateral connections may be important for recruitment as functional collateral vessels. The aim was to define the distribution of these connections and characterize their diameter and orientation.MethodsIn ex‐vivo canine hearts (n=6) the left main and right coronary artery were cannulated and filled with fluorescent resin (Batson #17). The hearts were prepared for our imaging cryomicrotome, sliced at 20 μm and block face images acquired. The stacks of about 4000 images were mathematically analyzed for vessel segments and pathways. Connections between branching subtrees were detected.ResultsIn average 400 connections per heart were found. Diameter distributions were skewed one sided to higher diameters with a mean peak value of 102.27±11.78 μm. In general orientation of these connections are parallel to the epicardium. Additionally, endocardial orientation was preferential parallel towards the longitudinal axis in contrast to midmyocard. The diameter distribution of the segments feeding a closed collateral pathway had a peak diameter of 220 μm. These segments were randomly distributed.ConclusionIn the dog, pre‐existing collateral connections are randomly distributed in the heart and therefore each coronary artery perfusion territory, large and small, has precursors for collateral vessels outgrowth.Supported by FP7‐ICT 2007224495 (euHeart)..

Efficacy of Longitudinal Speckle Tracking Strain in Conjunction with Isometric Handgrip Stress Test for Detection of Ischemic Myocardial Segments

Isometric handgrip stress test is a simple method for detecting coronary artery disease (CAD). However, the value of this method alone is limited by relatively low sensitivity. This study thus aimed to investigate the usefulness of two-dimensional speckle-tracking strain combined with handgrip for CAD patients. We studied 35 patients with stable angina pectoris who underwent percutaneous coronary intervention (PCI). Longitudinal (L-ɛ) and transverse peak systolic (T-ɛ) strains were measured from three standard apical views before and 1 month after PCI. Segments corresponded to perfusion territories of coronary arteries were divided into two groups based on coronary angiography results: stenotic (S) and nonstenotic (NS) segment. L-ɛ in S segments increased significantly after PCI, from -15.8% to -17.6% (P < 0.01), but not in NS segments. Moreover, L-ɛ in S segments increased significantly during handgrip before PCI, from -15.8% to -17.6% (P < 0.01), but decreased after PCI, from -17.6% to -16.7% (P = 0.02). In contrast, L-ɛ in NS segments decreased significantly during the isometric handgrip stress test before and after PCI (P < 0.05). Especially noteworthy is that a relative change in L-ɛ of >1.2% during handgrip before PCI could detect significant coronary stenosis with a sensitivity of 80%, specificity of 66%, and area under the curve of 0.77 (P < 0.001). On the other hand, no significant changes were observed in either T-ɛ segments during handgrip either before or after PCI. Longitudinal speckle-tracking strain combined with handgrip may constitute a valuable tool for detection of ischemic myocardial segments and prediction of improvement of regional contraction after revascularization.

An automatic method for quantification of myocardium at risk from myocardial perfusion SPECT in patients with acute coronary occlusion

BackgroundIn order to determine myocardial salvage, accurate quantification of myocardium at risk (MaR) is necessary. We present a validated novel automatic segmentation algorithm for quantification of MaR by myocardial perfusion SPECT (MPS) in patients with acute coronary occlusion. Methods and ResultsTwenty-nine patients with coronary occlusion were injected with a perfusion tracer before reperfusion, and underwent rest MPS within 4 hours. The MaR was quantified using the proposed algorithm (Segment software), the software Quantitative Perfusion SPECT (QPS) and by manual segmentation. The Segment MaR algorithm used a threshold of 55% of maximal counts and an a priori model based on normal coronary artery perfusion territories. The MaR was 30 ± 10% left ventricular mass (%LVM) by manual segmentation, 31 ± 12%LVM by Segment, and 36 ± 14%LVM by QPS. There was a good agreement between automatic and manual segmentation for both of the algorithms with a lower bias for Segment (.8 ± 4.0%LVM) than for QPS (5.8 ± 5.8%LVM) when compared to manual segmentation. ConclusionsThe Segment MaR algorithm can be used to correctly assess MaR from MPS images in patients with acute coronary occlusion without access to tracer-specific normal database. The MaR in relation to final infarct size enables determination of myocardial salvage.

Is Myocardial Ischemia the Cause of the Progressive Decrease in Ejection Fraction during Acute Decompensated Heart Failure ?

Is Myocardial Ischemia the Cause of the Progressive Decrease in Ejection Fraction during Acute Decompensated Heart Failure ?

XMR is a useful modality to guide, map and quantify the perfusion territories of coronary arteries

XMR is a useful modality to guide, map and quantify the perfusion territories of coronary arteries

Intracoronary Injection of Contrast Media Maps the Territory of the Coronary Artery: An MRI Technique for Assessing the Effects of Locally Delivered Angiogenic Therapies

The effects of locally delivered angiogenic factors or stem cells on the coronary artery perfusion territory are not well defined. Therefore, the aim of this study was to determine the ability of the selective injection of magnetic resonance contrast media (MR-CM) to map and quantify the territories of the major coronary arteries. Selective coronary catheterization (n = 16 pigs) was performed under x-ray and magnetic resonance imaging (MRI) fluoroscopy in an x-ray and magnetic resonance suite. Catheters were placed in the left anterior descending (LAD), circumflex, or right coronary artery. The coronary perfusion territories were mapped by the intracoronary injection of MR-CM using first-pass perfusion (FPP) and early contrast-enhanced (CE) MRI. Cine MRI was used to quantify left ventricular (LV) mass. In 12 animals, the LAD coronary artery was occluded by microspheres to create infarctions. Infarct size was measured on delayed enhanced (DE) MRI after the intravenous injection of MR-CM. X-ray and magnetic resonance fluoroscopy were successfully used to catheterize the coronary arteries. The perfusion territories of the coronary arteries were defined as hyperenhanced regions on FPP and CE MRI. The LAD coronary artery territory was 33.7 +/- 2.2% of LV mass on FPP MRI and 33.0 +/- 2.3% on CE MRI (P = .63). Bland-Altman analysis showed close agreement between the two methods (0.7 +/- 5.0%). DE MRI demonstrated the infarcted myocardium as hyperenhanced subregions of the perfusion territory (7.5 +/- 1.2% of LV mass). Interventional cardiac x-ray and magnetic resonance fluoroscopy can be used to map and quantify the perfusion territory of each coronary artery. This experimental method can be used before and after the local delivery of angiogenic factors and stem cell therapy to determine their efficacy.

Quantitative Echocardiographic Evaluation of Myocardial Perfusion Using Interrupted Contrast Infusion Technique: In Vivo Validation Studies and Feasibility in Human Beings

We recently developed a new approach for contrast echocardiographic quantification of myocardial perfusion, based on brief interruptions of contrast infusion, which was designed to overcome the limitations of existing techniques. In this study, our technique was initially validated in a series of animal experiments designed to detect regional perfusion variations in vivo. Subsequently, clinical feasibility of perfusion measurements was tested. Regional perfusion was measured transthoracically in 6 anesthetized pigs during baseline, partial left anterior descending coronary artery occlusion, and reperfusion, and validated with fluorescent microspheres. Adenosine-induced changes in perfusion were measured in 8 healthy volunteers. In both protocols, imaging was optimized during contrast infusion (Definity). Infusion was interrupted to allow contrast clearance and images were acquired during subsequent contrast inflow. Myocardial videointensity was measured over time and peak contrast inflow rate was calculated. In pigs, partial coronary occlusion resulted in a 47 +/- 23% decrease in peak contrast inflow rate in the left anterior descending coronary artery perfusion territory (P < .05), which was reversed during reperfusion, without concomitant decrease in other perfusion territories. These changes were in agreement with microspheres. In human beings, adenosine increased peak contrast inflow rate to 278 +/- 123% of baseline (P < .05). The interruption of contrast infusion technique is a sensitive tool for accurate quantification of myocardial perfusion, which may constitute an alternative to currently used techniques.

Long-term follow-up after deferral of coronary intervention based on myocardial fractional flow reserve measurement

To assess long-term results after deferring coronary intervention (percutaneous coronary intervention (PCI)) of an intermediate lesion with a value of myocardial fractional flow reserve (FFR) > or = 0.75 in a 'real life' patient population with no respect to results of stress tests (if performed) or coronary disease extent. PCI of an intermediate lesion was deferred in a group of 85 consecutive patients (54 men, 61+/-10 years) on the basis of the result of FFR > or = 0.75 (mean FFR, 0.89+/-0.06%). FFR was measured in 111 stenoses (mean diameter stenosis, 54+/-8%, left anterior descending coronary artery, 65 (58%), left circumflex coronary artery, 24 (22%), right coronary artery, 22 (20%). Multi-vessel disease (defined as visually assessed diameter reduction of more than 50% in at least two arteries of more than 1.5 mm diameter, supplying at least two of the three major coronary artery perfusion territories) was present in 67% of patients (one-vessel disease, 28 patients (33%), two-vessel disease, 39 patients (46%), three-vessel disease, 18 patients (21%). Recorded events during follow-up were as follows: all-cause death, cardiac death, non-fatal myocardial infarction, ischemia-driven target lesion transcatheter revascularization (TLR) and coronary artery bypass graft (CABG). Angina class (Canadian Cardiovascular Society (CCS) classification) and the need for anti-anginal drugs were recorded. Follow-up was completed in 85 patients (100%). Mean duration of follow-up was 22.6+/-6.6 months (range 4-33 months). Events occurred in 11 patients (13%). Seven patients died; this included two cardiac deaths. A non-fatal myocardial infarction occurred in one patient, one patient needed TLR and three patients underwent CABG. Estimated 33 month cardiac-event-free survival (Kaplan-Meier) was 91+/-4%. Angina class decreased [1.6+/-1.2 compared with 0.8+/-0.8 (P < 0.0001)] without difference with respect to the use of anti-anginal drugs (1.7+/-0.8 compared with 1.7+/-0.9, P = NS). Deferring coronary interventions of intermediate stenosis based on FFR measurement is safe with respect to long-term follow-up, irrespective of the extent of coronary artery disease.

Distal flow determinants in canine myocardium perfused through internal thoracic artery bypass grafts

The dynamic reactivity and the acute, recruitable flow capacity of an internal thoracic artery (ITA) graft remains unclear. These experiments were conducted in 20 anesthetized dogs with the left ITA grafted to the circumflex artery, off pump, using a brief local occlusion. The left main coronary artery was occluded, rendering the entire left ventricle, including anterior descending artery and circumflex regions, totally dependent on the ITA graft. When the left main coronary artery was occluded, the ITA flow immediately increased more than fivefold (93.4 +/- 9.6 mL/min; mean +/- standard deviation), representing an absolute flow value three times higher than ITA flow measured in situ on the chest wall (27.5 +/- 9.6 mL/min; p < 0.05 versus control), and the ITA graft provided total resting flow requirements (93.4 +/- 9.6 mL/min) for both left anterior descending and circumflex coronary artery perfusion territories at levels comparable with measured native flow values (y = (0.9555)x + 21.9272; r = 0.976; p < 0.05). Pharmacologic challenge with adenosine (0.2 mg.kg-1.min-1 intravenously) significantly increased the graft flow (120.3 +/- 18.7 mL/min; p < 0.05 versus control), but also significantly decreased the mean arterial pressure (85.4 +/- 5.0 versus 74.6 +/- 6.1 mm Hg; p < 0.05). Phenylephrine (0.003 mg.kg-1.min-1 intravenously) significantly decreased ITA graft flow (81.2 +/- 9.0 mL/min; p < 0.05 versus control) despite significantly increased perfusion pressure (84.8 +/- 6.3 versus 108.2 +/- 8.6 mm Hg; p < 0.05 versus control).(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Propagation Properties of Normal, Stunned, and Infarcted Myocardium

Identification of viable but stunned myocardium remains a major problem. Since stunned myocardium results in impairment of myocardial function without any structural damage and infarcted myocardium causes major structural disruption, we postulated that acoustic properties could distinguish between the two insults. Anesthetized open-chest dogs underwent a total occlusion of the left anterior descending coronary artery for 15 minutes (stunned, n = 7) and 90 minutes (infarcted, n = 8), followed by reperfusion for 3 hours. Circumflex coronary artery perfusion territory (n = 15) served as normal control tissue. Regions of myocardium were quantitatively evaluated with a scanning laser acoustic microscope operating at 100 MHz and a research ultrasound system operating at 4 to 7 MHz. Four ultrasonic parameters were determined: attenuation coefficient (an index of loss per unit distance), speed of propagation, a spatial variation of propagation speed called the heterogeneity index (HI), and ultrasonic backscatter at 5 MHz (IBR5). Myocardial water, lipid, and protein contents of normal, stunned, and infarcted myocardium were also determined. The attenuation coefficient of normal myocardium (179 +/- 20 dB/cm) was significantly greater than that of stunned (136 +/- 7 dB/cm, P < .001) and infarcted (130 +/- 8 dB/cm, P < .001) myocardium. The propagation speed of normal myocardium (1597 +/- 6 m/s) was similar to that of stunned (1600 +/- 6 m/s) and significantly higher than that of infarcted (1575 +/- 7 m/s, P < .001) myocardium. The HI for specimen thicknesses of 75 to 100 microns showed an increase of 33% between normal (5.0 +/- 0.8 m/s) and stunned (7.5 +/- 2.3 m/s, P < .05) myocardium. However, for the infarcted myocardium (5.8 +/- 2.0 m/s), the HI was essentially the same as that of the normal myocardium (5.0 +/- 0.8 m/s). The IBR5 of normal (-47.1 +/- 1.0 dB) was not significantly different from that of stunned myocardium (-46.8 +/- 0.9 dB). The IBR5 of infarcted myocardium (-42.4 +/- 1.0 dB) was significantly greater than that of normal myocardium. Myocardial water and protein contents were similar in the normal and stunned myocardium. Water content in the infarcted myocardium (80.8 +/- 2%) was significantly greater (P < .05) than in the normal (72.7 +/- 1.3%), and protein content of 18.5 +/- 0.7% was significantly lower (P < .05) than the normal (21.4 +/- 0.8%). Lipid content was increased in the stunned (8.5 +/- 0.5%) and virtually absent in the infarcted myocardium (0.8 +/- 0.3%) compared with normal (5.5 +/- 0.6%). We conclude that acoustic propagation properties can identify stunned and infarcted myocardium and may be related to biochemical/morphological differences.

Coronary artery disease: findings with GRE MR imaging and Tc-99m-methoxyisobutyl-isonitrile SPECT during simultaneous dobutamine stress.

This study compared gradient-recalled echo (GRE) magnetic resonance (MR) imaging with technetium-99m-methoxyisobutyl isonitrile (MIBI) single photon emission computed tomography (SPECT) during the same dobutamine stress for the localization of coronary artery stenoses. In 35 consecutive patients (28 men and seven women, aged 41-79 years) with angiographically documented coronary artery disease, corresponding GRE MR images and SPECT tomograms were acquired at rest and during dobutamine infusion and were evaluated for regional wall motion or perfusion abnormalities. Images in both examinations could be analyzed in 32 of 35 (91%) patients. Wall motion or perfusion abnormalities were observed in 27 of 32 (84%) GRE MR imaging and in 28 of 32 (87%) SPECT examinations. Sensitivity and specificity of dobutamine GRE MR imaging and dobutamine SPECT for the localization of left anterior descending coronary artery stenoses were 74% and 100% versus 70% and 100% for the combined left circumflex and right coronary artery perfusion territories. GRE MR imaging and SPECT have a high concordance with respect to the detection of a dobutamine-induced ischemic response.

Extent of atherosclerosis and remodeling of the left main coronary artery determined by intravascular ultrasound

This study used intravascular ultrasound (IU) to assess the incidence and extent of left main coronary artery (LMCA) disease and the effects of arterial remodeling. Sixty-nine patients undergoing cardiac catheterization were imaged with a 20 MHz rotational-tip IU device. Nine of the 69 studies (13%) could not be analyzed because of technical (n = 2) or anatomic (n = 7) reasons. Of the remaining 60 patients, 38 (63%) had at least 1 lesion in the left coronary artery perfusion territory by angiography; significant LMCA stenosis was present in 2 patients (3%). Intravascular ultrasonography demonstrated plaques in 27 of 60 LMCAs (45%), 6 of them in patients with normal angrograms. Twenty-four plaques (89%) were eccentric and calcium was present in 4 (15%). The mean minimal lumen diameter was 4.9 ± 0.8 mm, the maximal lumen diameter was 5.6 ± 0.8 mm, the planimetered lumen area was 22.6 ± 6.0 mm2, the plaque area was 3.9 ± 5.8 mm2, the vessel area was 26.5 ± 5.9 mm2, and the area stenosis was 13 ± 19%. In the 27 patients with plaque, plaque area was 8.7 ± 5.7 mm2 and the area stenosis was 30 ± 17%. The vessel area was significantly larger in diseased LMCAs (p < 0.001) and correlated with plaque area (r = 0.46). Iu examination of the LMCA was feasible in 87% of patients and was more reliable for delineating plaques than angiogaphy.