Myocardial Perfusion Disturbances Research Articles

Cardiac positron emission tomography in prediction of the clinical course of chronic thromboembolic pulmonary hypertension: prospective cohort study

INTRODUCTION: During the development of CTEPH maladaptive mechanisms in the right ventricle are accompanied by disturbances in myocardial energy metabolism and perfusion. These changes can be assessed visually and quantitatively using the molecular imaging method — PET with [18F]-FDG and [13N]-NH3.OBJECTIVE: Using cardiac PET/CT investigate the relationship between perfusion and metabolism of the right ventricular myocardium and the results of other instrumental examination methods in patients with CTEPH of different severity, as well as to calculate the threshold PET values to determine the group of patients with an unfavorable clinical course of the disease.MATERIALS AND METHODS: The study included 36 patients with a verified diagnosis of CTEPH, who were examined using a standard diagnostic protocol. Patients underwent cardiac PET/CT examinations with two radiopharmaceuticals: with [18F]-FDG to study the metabolism of the ventricular myocardium and with [13N]-NH3 to assess cardiac perfusion. For each radiopharmaceutical semi-quantitative accumulation indices (SUV) and the ratio of the levels of radiopharmaceutical uptake in the right and left ventricles (SUV RV/SUV LV) were obtained. Statistics: Shapiro-Wilk test, Student’s t-test, and Mann-Whitney U-test, Pearson correlation analysis, linear regression analysis, ROC analysis.RESULTS: The level of [18F]-FDG accumulation in the right ventricular myocardium is higher in patients with a high functional class of PH than in groups I, II (p<0.01). All indicators of SUV RV/SUV LV for [18F]-FDG demonstrate a direct linear relation-ship with the level of mean PAP (r=0.691, p<0.0001), PVR (r=0.715, p<0.0001), right ventricular size (r=0.658, p<0.0001), PASP (r=0.581, p<0.001) and inverse linear relationship with the functional parameters of the right ventricle CI (r=–0.555, p=0.001), CO (r=–0.488, p=0.005), TAPSE (r=–0.552, p<0.001), TAVS (r=–0.537, p<0.001), and SvO2 (r=–0.666, p<0.0001). A correlation was found between the accumulation of [13N]-NH3 and the main hemodynamic parameters used to assess the severity of the disease (СI, SvO2). The threshold values of [18F]-FDG and [13N]-NH3 accumulation indices have been obtained, which with high sensitivity (69.2–83.3%), specificity (68.4–94.7%) and diagnostic accuracy (0.73–0.83) make it possible to identify patients with a low cardiac index and an unfavorable prognosis.DISCUSSION: The obtained results confirm the presence of glucose hypermetabolism in right ventricular cardiomyocytes in the development of pulmonary hypertension and the association of these metabolic changes with the severity of PH. A significant correlation was demonstrated between the accumulation of both radiopharmaceuticals in the heart and the results of other examination methods characterizing the severity of disease and the prognosis of patients with CTEPH. Using a non-invasive PET/CT procedure, threshold values of PET parameters were obtained, which in the future can be used to identify patients with an unfavorable clinical prognosis.CONCLUSION: Cardiac PET/CT with [18F]-FDG and [13N]-NH3 is a promising non-invasive imaging technique that can be used to study metabolic and perfusion changes in the right ventricular myocardium in CTEPH, as well as to identify patients with a high risk of adverse events.

Endothelial inflammatory activation is related to myocardial perfusion disturbance in experimental chronic Chagas disease

Abstract Background Microvascular myocardial perfusion defect (MPD) is frequent in chronic Chagas cardiomyopathy (CCC) and may be involved in the pathophysiologic process that leads to left ventricular systolic dysfunction (LVSD). However, there is scarcity of studies addressing the histopathological meaning of MPD in CCC and its correlation with endothelial activation. Purpose To investigate the correlations between MPD detected in vivo with functional and histopathological changes in the experimental model of CCC in hamsters. Methods 24 female Sirius hamsters were investigated 8-months after intraperitoneal infection with 3.5x104 trypomastigote forms of Y-strain of T. cruzi. All animals were submitted to rest high-resolution 99mTc-Sestamibi-SPECT myocardial perfusion scintigraphy and echocardiography in vivo. The area of MPD was assessed through the calculation of polar maps by using a dedicated software (MunichHeart®) and a 13-segments model of LV. After euthanasia, we performed a histopathological study of cardiac inflammation and fibrosis and mRNA expression for TNF-α and ICAM, for assessment of inflammation and endothelial activation, respectively. Results Most of the animals presented MPD, n=17 (71%), its extension ranging from 1.4 to 30.3% of LV surface. We observed lower values of LVEF in animals with MPD (38.5±11.2%) when compared with animals without MPD 48.4±9.1%, p=0.04) and a trend to higher intensity of myocardial inflammation (estimated by the number of mononuclear cells) in animals with MPD (540.4±153.6 cell/mm2) vs. without MPD (409.6±130.3 cell/mm2), p=0.09. In addition, animals with MPD presented a higher ICAM (0.02±0.01) expression when compared with animals without MPD (0.01±0.01, p=0.02). There was no difference between groups regarding the extent of fibrosis. The results of the regression and correlation analysis showed that individual values of MPD area presented negative correlation with LVEF (R=−0.6, p=0.001), with echocardiographic wall motion score index (WMSi, R=0.5, p=0.007), and with the number of mononuclear cells (R=0.5, p=0.01). Moreover, an analysis based on myocardial segments (n=312), showed that segments with MPD (n=54) in comparison to those without MPD (n=258) presented higher number of mononuclear cells (608±299.9 cell/mm2 and 478.3±201.1 cell/mm, respectively, p<0.0001) and higher WMSi (1.8±0.9 and 1.2±0.4, respectively, p<0.0001. Conclusions MPD is a common finding in experimental model of CCC in hamsters and is correlated with inflammation, endothelial inflammatory activation, and systolic ventricular dysfunction. These results suggest that perfusion defects may be an in vivo surrogate marker for inflammation with potential translational implication for monitoring disease activity. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Fundação de Amparo à Pesquisa do Estado de São Paulo

High residual platelet aggregation in patients with coronary artery disease: a new methodological approach to detection

Aim. To develop a new methodological approach to assessment of collagen-induced platelet aggregation in patients with coronary artery disease (CAD) and to determine the quality of various methods for detecting high residual platelet reactivity (HRPR) to predict the risk of myocardial perfusion disturbance. Materials and methods. 36 patients (10 men and 26 women) aged 41–83 years and having stable CAD were examined. All patients had been undergoing continuous antiaggregation therapy for 6 months. We evaluated platelet aggregation using a laser analyzer with collagen as an aggregation inducer by the standard method 1 and our own patented method 2. The degree of platelet aggregation (%) and the size of aggregates in relative units (r.u.) in platelet-rich plasma were estimated. Myocardial perfusion scintigraphy with 99mTc-methoxy-isobutylisonitrile was performed according to a two-day stress-rest protocol. The summed stress score (SSS) values were used for analysis. SSS < 4 was regarded as normal myocardial perfusion. Results . The degree of platelet aggregation according to method 1 was 12 (5; 64)%, the aggregate size was 3 (2; 7) r.u. The degree of platelet aggregation according to method 2 was 44 (13; 78)%, and the aggregate size was 5 (4; 8) r.u. Method 2 allowed to diagnose the presence of myocardial ischemia with an aggregation degree ≥ 44.9% with sensitivity of 84% and specificity of 92% (area under the curve (AUC) = 0.89; p < 0.0001; odds ratio (OR) 2.18; 95% confidence interval (CI) 0.57–0.98) and an increase in aggregate size ≥ 4.80 r.u. with sensitivity of 84% and specificity of 84% (AUC = 0.95; p < 0.00001; OR 5.83; 95% CI 0.72–0.99). Conclusion. In patients with CAD, detection of high rates of collagen- induced platelet aggregation using the patented technique is associated with the risk of impaired myocardial perfusion. The developed new methodological approach to detection of HRPR allowed to determine high risk of atherothrombotic complications in additional 22% of the examined patients.

The value of cardiac sympathetic nervous system activity in the prognosis of atrial fibrillation radiofrequency ablation

Abstract Background Atrial fibrillation (AF) is one of the widest spread forms of arrhythmia worldwide. To date, radiofrequency catheter ablation (RFCA) of AF is a valuable treatment option. So far there are no clear predictors of the effectiveness of AF ablation. Nowadays, the association of cardiac sympathetic nervous system and the development and maintenance of AF has been showed. However, the association between sympathetic innervation disturbances and AF RFCA effectiveness remains inconclusive. Purpose To study the prognostic significance of cardiac sympathetic activity assessed by 123I-MIBG scintigraphy in AF RFCA efficacy. Methods The study included 46 patients. All patients were divided into 3 groups: I group - persistent AF (n=20), II group - long-standing persistent AF (LSPAF) (n=16), III group - sinus rhythm patients (n=10). All patients underwent 123I-MIBG and 99mTc-MIBI scintigraphy (planar and SPECT) to evaluate the cardiac sympathetic activity and myocardial perfusion, respectively. Echocardiography was performed in all patients to assess the cardiac contractile function. The effectiveness of interventional treatment was assessed in one year by 24 hour Holter monitoring. Results During a median follow-up of 12±6 month, arrhythmia recurrence was observed in 7 (35%) PAF patients and in 8 (50%) LSPAF patients. The univariate regression analysis showed that in patients with PAF the left atrial diameter (LAD), 123I-MIBG washout rate (WR), delayed 123I-MIBG defect score, and 123I-mIBG/99mTc-MIBI mismatch score were predictors of AF recurrence. In this group only the WR was a multivariate predictor of AF recurrence (odds ratios: 1.668, 95% confidence interval: 1.093–2.548, p=0.018). The receiver operator characteristics curve (ROC) analysis indicated the potential diagnostic value of WR to predict recurrence of AF after RFCA in PAF patients with an area under the curve of 0.968 (P<0.05; sensitivity = 100%, specificity = 45%), and an optimum cut-off value of 20.8%. The univariate regression analysis showed that in patients with LSPAF the LAD, WR, delayed 123I-MIBG defect score, rest perfusion defect score and 123I-MIBG/99mTc-MIBI mismatch score were predictors of AF recurrence. According to multivariate analysis only the 123I-MIBG/99mTc-MIBI mismatch score was an independent predictor of AF recurrence in this group of patients (odds ratios: 2.155, 95% confidence interval: 1.192–3.897, p=0.011). ROC analysis gave an optimum cut-off value of 12.5% for the 123I-MIBG/99mTc-MIBI mismatch score with an area under the curve of 0.942 to predict recurrence of AF after RFCA in LSPAF patients (p<0.05, sensitivity = 81%, specificity = 28%). Conclusions In AF patients the incidence of arrhythmia recurrence after RFCA is associated with impaired sympathetic nervous activity. The prognosis of AF recurrence in LSPAF patients has a link with rest myocardial perfusion disturbances which may reflect the severer structural change of myocardium. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Russian Science Foundation

P6434Evaluation of the nociceptive flexor reflex, as a new method for the diagnosis of microvascular angina

Abstract The purpose of this study was to study the diagnostic value of the nociceptive flexor reflex (NFR) method in patients with microvascular angina. Materials and methods The study included 49 patients with MVA (main group), 40 patients with classical angina II-III f.c. (comparison group 1), 42 patients with silent myocardial ischemia (comparison group 2) and 32 healthy volunteers (control group). Criteria for inclusion in the group with MVA: chest pain, positive stress test, unchanged coronary arteries according to coronary angiography, the presence of myocardial perfusion disturbance and reduction of the coronary reserve according to positiron-emission tomography of the myocardium at rest, with adenosine and cold one test. Chest pain syndrome was observed in all 49 patients. All subjects studied the functional activity of nociceptive and antinociceptive systems using the nociceptive flexor reflex method on the equipment of expert class electromyography system, the pain threshold (Pb) values, the reflex threshold (Pr) were calculated and the ratio of pain and reflex threshold was calculated to calculate the pain threshold / threshold reflex (Pb/Pr), which in healthy people is about 0.9–1.0. Results and discussion In te study of NFR in patients with MVA in the group as a whole, a decrease in the pain threshold, reflex threshold and Pb/Pr ratio compared with normal values were found. The pain threshold in patients in the group was lower (statistically significantly) when compared with the group 1, the group 2 and the control group (p<0.0001; p<0.0001; p<0.0001, respectively). The reflex threshold in patients of the MCC group was also significantly lower when compared with the group 1, the group 2 and the control group (p<0.001; p<0.0001; p<0.001, respectively). Due to the fact that the low pain threshold was found in 84.4% of the examined patients with MVA who had microvascular dysfunction according to positron-emission tomography, we evaluated the prognostic value of the NFR method for diagnosing the disease. To do this, an assessment was made of the odds ratio (OR) of identifying MVA in groups of patients with different levels of index K (the ratio of the pain threshold value to the reflex threshold value). We have chosen the value of index K with the highest specificity and high sensitivity equal to 0.8892. Based on the data obtained, the diagnostic value of the NFR method was calculated during the verification of the MVA. When conducting a mathematical analysis, it was found that this technique has high sensitivity (84.4%), specificity (95.12%), positive (90.48%) and negative predictive value (91.76%). We have not found information in the literature on the use of the NFR assessment method and its diagnostic value in MVA. Findings Due to the high diagnostic value of determining the NFR, we propose to include this method in the MVA diagnostic algorithm as an additional one.

Влияние коррекции поглощения гамма-излучения при исследовании перфузии миокарда методом ОФЭКТ/КТ

Purpose: Assessment of the impact of absorption correction (AC) on quantitative parameters of myocardial perfusion and determination of the extent of stress-induced myocardial microcirculation disorders on SPECT / CT in patients with chest pain and unchanged coronary arteries.
 Material and methods: the study included 35 patients, each of whom was carried a selective coronary angiography and rest/stress SPECT/CT of the myocardium with 99mTc -MIBI with- and without CA.
 Results: In all patients with stress-induced myocardial ischemia was detected both without and with AC images. However, quantitative parameters of myocardial perfusion were lower after the AC: SSS 6.9 ± 1.2 vs. 7.7 ± 1.1; SDS 4.0 ± 0.8 vs. 4.9 ± 0.6; Stress ext. Total 11.2 ± 1.8 vs. 13.0 ± 1.9; Stress TPD total 9.3 ± 1.2 vs.10.9 ± 1.2; TPDi 4.1 ± 1.0 vs.5.9 ± 0.9 (for all p < 0.05). For SRS, Rest ext. Total, and Rest TPD total difference was not significant. The number of hypoperfused segments, according to the segmental analysis, was less after AC and was 126 vs. 153 at rest, 242 vs. 177 under stress.
 In women, significant difference was obtained for all parameters, for men – only for the SSS, SDS, Stress ext. Total, Stress TPD total. In patients with BMI ≥25 significant difference for all parameters was obtained. However, patients with the normal BMI (18,5–24,9;WHO, 2004) significant difference was obtained only for Stress ext. Total, Stress TPD total.
 Conclusion The use of SPECT/CT with AC allow to detect microcirculatory violations of perfusion and myocardial reserve perfusion in patients with pain in the chest with the unchanged CA, as evidenced by indicators of the average values of quantitative parameters of perfusion scintigram. The most significant impact on the quantitative perfusion parameters was observed in women with well-developed breasts and obese patients. The findings give reason to assume the use of AC to avoid revaluation incidence and severity of stress-induced myocardial perfusion disturbances.

P3428Prospective controlled trial testing the effect of physical training over myocardial perfusion disturbance and quality of life in patients with primary microvascular angina: a pilot study

P3428Prospective controlled trial testing the effect of physical training over myocardial perfusion disturbance and quality of life in patients with primary microvascular angina: a pilot study

P5413Regional myocardial perfusion disturbance in experimental model of chronic Chagas cardiomyopathy

P5413Regional myocardial perfusion disturbance in experimental model of chronic Chagas cardiomyopathy

Perfusion, Metabolism and Regional Myocardial Contractility in Patients With Valvular Heart Disease: a Long-Term Follow-Up After Valve Replacement

To perform complex assessment of myocardial perfusion, metabolism, and regional contractility in patients with valvular heart disease (VHD) in remote period after surgical correction of heart defects. We examined 30 patients with VHD in 1-8 years after heart valve replacement because of mitral (n=13) or aortic (n=17) valve defects of the following etiology: rheumatic heart disease (n=10), degeneration of connective tissue (n=13), infective endocarditis (n=7). For assessment of myocardial perfusion, metabolism, and regional contractility, we used single photon emission computed tomography (SPECT). Myocardium of patients who had undergone surgical correction of heart valve defects was characterized by dominating diffuse sclerotic changes localized mostly in basal segments. Hibernating myocardium was a less frequent finding. There were segments of borderline state with normal parameters of metabolism but slight impairment of perfusion without pronounced disturbances of kinetics. Patients with infectious etiology of valvular defects had combined perfusion and metabolic changes in multiple myocardial segments. Extensive derangements of perfusion and metabolism were characteristic for patients with connective tissue degeneration. Signs of cardiac failure caused by disturbances of myocardial perfusion and metabolism in patients with valvular heart disease can persist even after successful correction of valvular defect with normalization of intracardiac hemodynamics.

Perioperative myocardial perfusion: an anesthesiologists' concern?

Cardiac complication following noncardiac surgery is the leading cause of death in the perioperative period. Disturbances in myocardial perfusion are at the basis of these complications. The purpose of this review was to summarize the most recent findings on factors affecting myocardial perfusion in the perioperative period and possibilities for monitoring disturbances in myocardial perfusion. Clinical studies in cardiovascular healthy patients show mild influences of general anesthetics on myocardial perfusion. No clear benefit could be detected for the use of volatile anesthetics over intravenous anesthetics in patients at risk for disturbances in myocardial perfusion. Etomidate should be used with caution in American Society of Anesthesiologists class 3 and 4 patients. Recent studies focused on effects of decreased perfusion pressure, lowering myocardial oxygen demand and impaired oxygen delivery on myocardial perfusion. Promising results are reported on monitoring perioperative myocardial perfusion using troponin and NT-pro-B-type natriuretic peptides. General anesthesia only mildly influences myocardial perfusion in cardiovascular healthy patients. Further research is necessary to determine whether this is also the case for cardiovascular-compromised patients. Monitoring troponin levels in the perioperative setting may be useful for predicting cardiovascular events in at-risk patients.

Rest myocardial perfusion disturbance is related to inflammation but not to fibrosis inexperimental chronic chagas cardiomyopathy

Purpose: Myocardial perfusion disturbance is a common finding in human chronic Chagas cardiomyopathy (CC), but its underlying tissue changes and pathophysiologic mechanisms are unclear. We aimed at investigating the histologic changes related to the myocardial perfusion changes detected in an experimental model of CC in hamsters. Methods: Female Syrian hamsters (n=34) were infected with 35.000 or 100.000 trypomastigotes forms of T. cruzi Y-strain and were submitted to in vivo imaging 6 to 10 months afterwards. High-resolution rest Sestamibi-Tc-99m-SPECT imaging was used for detection of myocardial perfusion defects (MPD), defined as segments with uptake <50% of the maximum pixel uptake value on polar maps analysis. The segmental and global left ventricular (LV) function was assessed by using 2D-Echocardiogram. Ex vivo histologic analysis included quantitation of fibrosis (picrosirius red) and inflammatory infiltrate. A 13-segment model of LV segmentation was used for all imaging analyses and histologic topographic correlations. Results: MPD were found in 17 (50%) of the infected animals. No transmural scar was detected in segments with MPD. The subgroup of animals with MPD, in comparison to animals without MPD, showed: 1) reduced LV ejection fraction (65±21 and 81±9%, respectively, p<0.01); 2) larger inflammatory infiltrate (172.8±89 and 111.5±54 nuclei/mm2; p=0.04); 3) higher segmental wall motion score (1.44±0.5 and 1.04±0.05%; p=0.003); 4) but similar extent of fibrosis (8.4±3.9; 6.6±3.2%; p=0.06). There was a significant association between regional MPD and abnormal wall motion (p<0,001). The segments with MPD (n=57) as compared to the segments with normal perfusion (n=487) showed larger extent of inflammatory infiltrate (175.8±145.0 and 111.6±69.2 nuclei/mm2, respectively; p=0.001), higher segmental wall motion score (1.65±0.6 and 1.1±0.4; p<0.0001) and comparable extent of fibrosis (10.5±18.6 and 7.4±6.2%; p=0.37). Conclusions: Rest MPD in experimental CC is topographically correlated to inflammatory changes that are intense enough to be associated to wall motion impairment. The fact that these derangements are not due to fibrosis opens the possibility that therapeutic interventions aimed at reducing the degree of myocardial inflammation and/or hypoperfusion may favorably impact on the natural history of this model of experimental CC.

Left ventricular morphology and function in diabetic and nondiabetic hemodialyzed patients

Morbidity in end-stage renal disease (ESRD) diabetic patients is worse than in patients without diabetes mellitus (DM). This study aims to compare clinical, laboratory, and echocardiographic features between the ESRD patients with and without DM. Fifty-eight ESRD patients on dialysis were prospectively divided into two groups according to the presence of DM. Demographic, clinical, laboratory, and echocardiographic features (ejection fraction and wall motion score index) were compared between the two groups. Overall, 20 out of 58 patients (37.8%) with ESRD had DM. There were no significant differences between the patients with DM and those without DM when it comes to age (60.6 ± 10.6 vs. 59.0 ± 10.6 years, P = 0.665), ejection fraction (52.6% ± 12.8% vs. 54.2% ± 12.8%, P = 0.59), and wall motion score index (1.21 ± 0.3 vs.1.15 ± 0.3, P = 0.37). In multivariant analysis of the interventricular septum, posterior wall thickness and left atrium size correlated positively with DM. There was also no statistical difference in myocardial perfusion disturbances on real-time contrast echocardiography between the groups with and without DM (12 (60%) patients vs. 14 patients (36.8%), P = 0.079). Among diabetics 77.8% had significant atherosclerotic changes, while in the group without DM, only 38.1%, P = 0.01. From the laboratory parameters ferritin and high-sensitivity C-reactive protein levels were significantly higher in the group with DM, P = 0.014 and P = 0.026, respectively. Patients with ESRD and DM have significantly bigger left atrial size, thicker left ventricular walls, and higher serum ferritin and high-sensitivity C-reactive protein levels than the patients without DM. The aforementioned features may be possible risk factors for the development of adverse cardiac events in patients on hemodialysis.

Albuminuria and VEGF as early markers of cardiovascular disturbances in young type 1 diabetic patients

Aims The aim of the study was to assess myocardial perfusion by means of non-invasive diagnostic methods and measurement of the plasma concentration of vascular endothelial growth factor (VEGF) in patients with long-lasting type 1 diabetes. Methods and results The study was performed on 41 Type 1 diabetic patients (23 females, 18 males), aged 30 ± 7.6 with a duration of disease 15.2 ± 5.5 years. 17 patients exhibited microalbuminuria (10 females, 7 males) and 24 subjects were without microalbuminuria (13 females, 11 males). The methods used included a 24-h ECG tape, an exercise treadmill test, echocardiological evaluation with dobutamine and atropine challenge and single photon emission computer tomography (SPECT) at rest, and after dipyridamol induction of ischemia. All the exercise and stress echocardiography tests were negative. There were significant differences between microalbuminuric and normoalbuminuric subjects in the duration of their exercise tests (586.9 ± 110.5 vs. 664.9 ± 133.2 s, p = 0.027), performed work (11.4 ± 1.6.vs. 12.6 ± 1.8 METs, p = 0.045), achieved pulse limit (89.1 ± 3.6 vs. 92.6 ± 5.2%, p = 0.037), rest ejection fraction (55.8 ± 8.7 vs. 62.0 ± 4.4%, p = 0.040), abnormal changes in SPECT (53 vs. 21%, p = 0.047) and VEGF concentration (101.5 ± 7.8 vs. 75.15 ± 16.5 pg/ml, p < 0.05). The presence of retinopathy increased 12-fold the probability of significant changes in the SPECT (OR 12.1, 95% CI 1.38–105.64, p = 0.02) and nephropathy (OR 4.27; 95%CI 1.09–16.83, p = 0.03). Conclusion Asymptomatic patients with long lasting type 1 diabetes may have disturbances in myocardial perfusion, especially these with microalbuminuria.

Changes in Myocardial Perfusion Correlate With Deterioration of Left Ventricular Systolic Function in Chronic Chagas' Cardiomyopathy

This study aimed at analyzing the association between myocardial perfusion changes and the progression of left ventricular systolic dysfunction in patients with chronic Chagas' cardiomyopathy (CCC). Pathological and experimental studies have suggested that coronary microvascular derangement, and consequent myocardial perfusion disturbance, may cause myocardial damage in CCC. Patients with CCC (n = 36, ages 57 +/- 10 years, 17 males), previously having undergone myocardial perfusion single-positron emission computed tomography and 2-dimensional echocardiography, prospectively underwent a new evaluation after an interval of 5.6 +/- 1.5 years. Stress and rest myocardial perfusion defects were quantified using polar maps and normal database comparison. Between the first and final evaluations, a significant reduction of left ventricular ejection fraction was observed (55 +/- 11% and 50 +/- 13%, respectively; p = 0.0001), as well as an increase in the area of the perfusion defect at rest (18.8 +/- 14.1% and 26.5 +/- 19.1%, respectively; p = 0.0075). The individual increase in the perfusion defect area at rest was significantly correlated with the reduction in left ventricular ejection fraction (R = 0.4211, p = 0.0105). Twenty patients with normal coronary arteries (56%) showed reversible perfusion defects involving 10.2 +/- 9.7% of the left ventricle. A significant topographic correlation was found between reversible defects and the appearance of new rest perfusion defects at the final evaluation. Of the 47 segments presenting reversible perfusion defects in the initial study, 32 (68%) progressed to perfusion defects at rest, and of the 469 segments not showing reversibility in the initial study, only 41 (8.7%) had the same progression (p < 0.0001, Fisher exact test). In CCC patients, the progression of left ventricular systolic dysfunction was associated with both the presence of reversible perfusion defects and the increase in perfusion defects at rest. These results support the notion that myocardial perfusion disturbances participate in the pathogenesis of myocardial injury in CCC.

Neonatal Kawashima Intraventricular Repair for Taussig-Bing Anomaly with Oblique Relationship of the Great Arteries

An arterial switch operation is considered the procedure of choice for the repair of Taussig-Bing anomaly, because it can be performed in most patients. However, after taking problems such as neoaortic insufficiency or myocardial perfusion disturbances after the arterial switch operation into account, intraventricular repair might be reconsidered as an option in selected patients. We present a case of Taussig-Bing anomaly in a patient with an oblique relationship of the great arteries, which was successfully managed by Kawashima intraventricular repair in the neonatal period, and discuss the feasibility of this option with a review of the literature.

Acute left ventricular dysfunction of severe scorpion envenomation is related to myocardial perfusion disturbance

Background Scorpion envenomation (SE) may present severe cardiac dysfunction with acute pulmonary edema and cardiogenic shock. The pathophysiology of this acute heart failure is still controversial. We aimed at assessing the contribution of the myocardial ischemia to the left ventricular dysfunction in SE by using 99mTc-Sestamibi myocardial perfusion scintigraphy (MPS). Methods Twelve children (7 males, 1–12 years old) presenting severe Tityus serrulatus envenomation were prospectively submitted to MPS within 72 h (acute) and 15 days (follow-up) after the event. MPS images were interpreted using a visual semi-quantitative uptake score (0 = normal, 4 = absent). Echocardiography was used for the assessment of left ventricular (LV) ejection fraction (EF) and regional wall motion (WM) by using a semi-quantitative score (0 = normal, 4 = akinesia). A 16-segment LV model was used. Results Initial echocardiography showed marked WM abnormalities with a mean score of 31.4 ± 13.9, and a reduced EF (36 ± 16%). All patients exhibited myocardial perfusion (MP) defects. The mean MP uptake score was 14.6 ± 7.8. A significant topographic association between MP and WM changes was obtained ( p < 0.0001, Fischer exact test). A positive correlation was obtained between the summed WM and MP scores ( R = 0.68, p = 0.016). Follow-up evaluation showed a significant improvement of LVEF (65 ± 10%) and WM score (3.9 ± 4.2), parallel to the normalization of MP. Conclusions These observations strongly support the participation of transitory myocardial ischemia in the mechanism of the acute cardiac dysfunction caused by severe scorpion envenoming. Micro vascular spasm related to the catecholamine over stimulation may be the pathophysiologic link triggering the myocardial perfusion disturbance in this syndrome.

Ventricular tachycardia in Chagas' disease: a comparison of clinical, angiographic, electrophysiologic and myocardial perfusion disturbances between patients presenting with either sustained or nonsustained forms

Ventricular tachycardia (VT) is common among patients with Chagas' heart disease but the ultimate mechanisms responsible for its sustained and nonsustained forms are not understood. This study aimed at determining which factors differentiate between patients with sustained (S-VT) and nonsustained VT (NS-VT). Fifty-six consecutive chagasic patients with VT were prospectively selected: 28 patients with spontaneous S-VT and 28 patients with NS-VT. The patients underwent clinical, angiographic, electrophysiologic and myocardial perfusion examination. Syncope episodes (S-VT: 43% versus NS-VT: 11%, p=0.007) and induction of S-VT by programmed ventricular stimulation (S-VT: 89% versus NS-VT: 7%, p=0.001) were significantly more frequent in S-VT patients. Evidence of a scar-related reentry was observed in all 24 S-VT patients who underwent endocardial mapping for attempted radiofrequency ablation of 33 VTs. Overall, 29 VTs arose from the LV (88%) and 4 VTs arose from the RV (12%). Among these, 27 VTs (82%) were related to LV inferolateral scar, 2 VTs (6%) were related to LV apical scar, and 4 VTs (12%) were related to RV scars. A significantly higher prevalence of wall motion abnormalities (S-VT: 82% versus NS-VT: 46%, p=0.005) and myocardial perfusion defects (basal segments, S-VT: 95.5% versus NS-VT: 44%, p=0.001) was documented within the LV inferior and/or posterolateral regions in S-VT patients compared to NS-VT. In conclusion: (a) VT may arise from various regions in both ventricles, but LV inferolateral scar is the main source of S-VT reentrant circuits; (b) there is good topographic correlation between myocardial perfusion, wall motion abnormalities and areas that originate S-VT; (c) although to a lesser extent, wall motion and perfusion defects also occur in a relevant proportion of chagasics with NS-VT.

Myocardial perfusion and adrenergic innervation in patients with RBBB and LAfB: the effect of altering the activation sequence with right ventricular apical pacing.

The aim of this study was to investigate myocardial perfusion and adrenergic innervation in patients with intraventricular conduction disturbances and to detect any changes caused by alteration of the ventricular activation sequence as a result of right ventricular apical pacing. We studied 15 patients with right bundle branch block (RBBB) and left anterior fascicular block (LAFB), while 15 healthy individuals served as controls. All patients underwent planar and single-photon emission computed tomography (SPECT) myocardial imaging after intravenous infusion of 5mCi 123I-metaiodobenzylguanidine (123I-MIBG) and a SPECT thallium201 myocardial perfusion study before and 3 months after pacemaker implantation. The heart to mediastinum ratio was calculated during the 123I-MIBG study in order to assess the global cardiac sympathetic activity and was significantly smaller in patients than in controls (P < 0.001). Patients with RBBB and LAFB revealed regional adrenergic innervation defects, mostly in the inferior and posterior walls. After a medium-term pacing period, a redistribution of 123I-MIBG uptake was detected, with aggravation of adrenergic innervation defects in the apical and posterior walls and amelioration in septal and anterior walls. Five patients showed perfusion defects that remained unchanged after pacing. Two others displayed mild myocardial perfusion defects that did not exist before pacing. In conclusion, patients with RBBB and LAFB reveal global and regional disturbances of myocardial adrenergic innervation, which shows redistribution as a result of the altered propagation of the ventricular electrical activation. To a smaller degree these patients reveal myocardial perfusion disturbances in which pacing has a limited medium-term effect.

Relation of regional sympathetic denervation and myocardial perfusion disturbance to wall motion impairment in Chagas’ cardiomyopathy

Impairment of sinus node autonomic control and myocardial perfusion disturbances have been described in patients with chronic Chagas’ cardiomyopathy. However, it is not clear how these conditions contribute to myocardial damage. In this investigation, iodine-123 (I-123) meta-iodobenzylguanidine (MIBG) and thallium-201 myocardium segmental uptake were studied in correlation with the severity of left ventricular (LV) dysfunction detected in various phases of Chagas’ heart disease. Group I consisted of 12 subjects (43 ± 4 years, 7 men) with no symptoms and no cardiac involvement on electrocardiogram (ECG) or echocardiography; group II consisted of 13 patients (48 ± 3 years, 9 men) with abnormal resting ECG and/or echocardiographic segmental abnormalities, and LV ejection fraction of ≥0.5; group III was comprised of 12 patients (59 ± 3 years, 10 men) with more severe heart disease, LV dilation, and LV ejection fraction of <0.5. Eighteen control volunteers (38 ± 3 years, 9 men) were also included in the study. I-123 MIBG single-photon emission computed tomographic (SPECT) segmental uptake defects were observed in group I (33%), group II (77%), and group III (92%). Quantitative analysis showed mean areas of reduced LV I-123-MIBG uptake: group I was 3.7 ± 2.1%; group II was 8.3 ± 2.3%; and group III was 19.0 ± 3.3%. The differences between group I and both groups II and III were statistically significant (p <0.001, analysis of variance test). Myocardial perfusion defects (reversible, fixed, and paradox) were observed in group I (83%), group II (69%), and group III (83%). A marked topographic association between perfusion, innervation, and wall motion abnormalities (assessed by gated-SPECT perfusion studies) was observed in all the groups. Defects predominated in the inferior, posterior lateral, and apical LV regions. Thus, extensive impairment of cardiac sympathetic function at the ventricular level occured early in the course of Chagas’ cardiomyopathy and was related to regional myocardial perfusion disturbances, before wall motion abnormalities. Both conditions are associated with progression of ventricular dysfunction.

Effects of exposure to low concentrations of carbon monoxide on exercise performance and myocardial perfusion in young healthy men.

OBJECTIVE: To assess the effects of exposure to low concentrations of carbon monoxide (CO), as commonly measured in atmospheric urban air pollution and certain occupational environments, on exercise performance and...