Long-term survival after a massive left ventricular infarction evidenced by FDG-PET and leaving intact only the septal wall

There is evidence that survival remains possible for infarction greater than 50% of the left ventricle in human, as well as in the rat infarct model. To our knowledge, survival has not been documented for infarctions involving the anterior, inferior and lateral wall leaving intact only the septal wall. An adult rat underwent a ligation of the left anterior descending coronary artery. ECG-triggered (18)F-ffluorodeoxyglucose Positron Emission Tomography revealed that 72% of the left ventricle was necrotic and totally akinetic. Although the left ventricular ejection fraction was severely impaired (9%), this rat survived and was asymptomatic after 2 months. The exact reasons for this incredible survival are still unclear.

Repairing chronic myocardial infarction with autologous mesenchymal stem cells engineered tissue in rat promotes angiogenesis and limits ventricular remodeling

Background

Tissue engineering scaffold constitutes a new strategy of myocardial repair. Here, we studied the contribution of a patch using autologous mesenchymal stem cells (MSCs) seeded on collagen-1 scaffold on the cardiac reconstruction in rat model of chronic myocardial infarction (MI).

Methods

Patches were cultured with controlled MSCs (growth, phenotype and potentiality). Twenty coronary ligated rats with tomoscingraphy (SPECT)-authenticated transmural chronic MI were referred into a control group (n = 10) and a treated group (n = 10) which beneficiated an epicardial MSC-patch engraftment. Contribution of MSC-patch was tested 1-mo after using non-invasive SPECT cardiac imaging, invasive hemodynamic assessment and immunohistochemistry.

Results

3D-collagen environment affected the cell growth but not the cell phenotype and potentiality. MSC-patch integrates well the epicardial side of chronic MI scar. In treated rats, one-month SPECT data have documented an improvement of perfusion in MI segments compared to control (64 ± 4% vs 49 ± 3% p = 0.02) and a reduced infarction. Contractile parameter dp/dtmax and dp/dtmin were improved (p & 0.01). Histology showed an increase of ventricular wall thickness (1.75 ± 0.24 vs 1.35 ± 0.32 mm, p &0.05) and immunochemistry of the repaired tissue displayed enhanced angiogenesis and myofibroblast-like tissue.

Conclusion

3D-MSC-collagen epicardial patch engraftment contributes to reverse remodeling of chronic MI.

Beige differentiation of adipose depots in mice lacking prolactin receptor protects against high-fat-diet-induced obesity

Stimulating conversion of white fat to metabolically active adipocytes (beige fat) constitutes a promising strategy against weight gain and its deleterious associated-disorders. We provide direct evidence that prolactin (PRL), best known for its actions on the mammary gland, plays a pivotal role in energy balance through the control of adipocyte differentiation and fate. Here we show that lack of prolactin receptor (PRLR) causes resistance to high-fat-diet-induced obesity due to enhanced energy expenditure and increased metabolic rate. Mutant mice displayed reduced fat mass associated with appearance of massive brown-like adipocyte foci in perirenal and subcutaneous but not in gonadal fat depots under a high-fat diet. Positron emission tomography imaging further demonstrated the occurrence of these thermogenic brown fat depots in adult mice, providing additional support for recruitable brown-like adipocytes (beigeing) in white fat depots. Consistent with the activation of brown adipose tissue, PRLR inactivation increases expression of master genes controlling brown adipocyte fate (PRDM16) and mitochondrial function (PGC1α, UCP1). Altered pRb/Foxc2 expression suggests that this PRL-regulated pathway may contribute to beige cell commitment. Together, these results provide direct genetic evidence that PRLR affects energy balance and metabolic adaptation in rodents via effects on brown adipose tissue differentiation and function.

Left ventricle fibrosis associated with nonsustained ventricular tachycardia in an elite athlete: is exercise responsible? A case report

OBJECTIVE

To emphasize the potentially harmful effects of high-intensity exercise on cardiac health and the fine line between physiologic and pathologic adaptation to chronic exercise in the elite athlete. This case also highlights the crucial need for regular evaluation of symptoms that suggest cardiac abnormality in athletes.

BACKGROUND

Sudden cardiac death (SCD) of young athletes is always a tragedy because they epitomize health. However, chronic, high-intensity exercise sometimes has harmful effects on cardiac health, and pathologic changes, such as myocardial fibrosis, have been observed in endurance athletes. In this case, a highly trained 30-year-old cyclist reported brief palpitations followed by presyncope feeling while exercising. Immediate investigations revealed nonsustained ventricular tachycardia originating from the left ventricle on a stress test associated with myocardial fibrosis of the left ventricle as shown with magnetic resonance imaging. Despite complete cessation of exercise, life-threatening arrhythmia and fibrosis persisted, leading to complete restriction from competition. Differential Diagnosis: Hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, myocarditis, postmyocarditis, use of drugs and toxic agents, doping, and systemic disease.

TREATMENT

The arrhythmia could not be treated with catheter ablation procedure or drug suppression. Therefore, the athlete was instructed to withdraw completely from sport participation and to have a medical follow-up twice each year.

UNIQUENESS

To our knowledge, no other report of left ventricle exercise-induced fibrosis associated with life-threatening arrhythmia in a living young elite athlete exists. Only postmortem evidence supports such myocardial pathologic adaptation to exercise.

CONCLUSIONS

To prevent SCD in young athletes, careful attention must be paid to exercise-related symptoms that suggest a cardiac abnormality because they more often are linked to life-threatening cardiovascular disease.

Experimental model of naturally occurring post-radiation sarcoma: interest of positron emission tomography (PET) for early detection

Radiotherapy is an integral part of overall cancer therapy. One of the most serious adverse effects of irradiation concern, for long-term survivors, the development of post-radiation sarcoma (PRS) in healthy tissues located within the irradiated area. PRS have bad prognosis and are often detected at a late stage. Therefore, it is obvious that the early detection PRS is a key-point and the development of preclinical models is worthy to evaluate innovative diagnostic and therapeutic procedures. The aim of this study was to develop a spontaneous rodent model of PRS and to evaluate the potency of Positron Emission Tomography (PET) for early detection. Fifteen Wistars rats were irradiated unilateraly on the hindlimb with a single dose of 30 Gy. Sequential analysis was based on observational staging recordings, Computerized Tomography (CT) scanning and PET. Tumors were removed and, histopathological and immunochemistry analyses were performed. Among the irradiated rats, 12 sarcomas (80%) were detected. All tumors occurred naturallty within the irradiated hindlimb and were highly aggressive since most tumors (75%) were successfully transplanted and maintained by serial transplantation into nude mice. Upon serial staging recordings, using PET, was found to enable the detection of PRS earlier after irradiation than with the other methods (i.e. 11.9 ± 1.8 vs 12.9 ± 2.6 months). These results confirmed the interest of experimental models of PRS for the preclinical evaluation of innovative diagnostic strategies and confirmed the potency of PET for early detection of PRS. This preclinical model of PRS can also be proposed for the evaluation of therapeutic strategies.

Transforming growth factor β receptor 1 is a new candidate prognostic biomarker after acute myocardial infarction

BACKGROUND

Prediction of left ventricular (LV) remodeling after acute myocardial infarction (MI) is clinically important and would benefit from the discovery of new biomarkers.

METHODS

Blood samples were obtained upon admission in patients with acute ST-elevation MI who underwent primary percutaneous coronary intervention. Messenger RNA was extracted from whole blood cells. LV function was evaluated by echocardiography at 4-months.

RESULTS

In a test cohort of 32 MI patients, integrated analysis of microarrays with a network of protein-protein interactions identified subgroups of genes which predicted LV dysfunction (ejection fraction ≤ 40%) with areas under the receiver operating characteristic curve (AUC) above 0.80. Candidate genes included transforming growth factor beta receptor 1 (TGFBR1). In a validation cohort of 115 MI patients, TGBFR1 was up-regulated in patients with LV dysfunction (P < 0.001) and was associated with LV function at 4-months (P = 0.003). TGFBR1 predicted LV function with an AUC of 0.72, while peak levels of troponin T (TnT) provided an AUC of 0.64. Adding TGFBR1 to the prediction of TnT resulted in a net reclassification index of 8.2%. When added to a mixed clinical model including age, gender and time to reperfusion, TGFBR1 reclassified 17.7% of misclassified patients. TGFB1, the ligand of TGFBR1, was also up-regulated in patients with LV dysfunction (P = 0.004), was associated with LV function (P = 0.006), and provided an AUC of 0.66. In the rat MI model induced by permanent coronary ligation, the TGFB1-TGFBR1 axis was activated in the heart and correlated with the extent of remodeling at 2 months.

CONCLUSIONS

We identified TGFBR1 as a new candidate prognostic biomarker after acute MI.

Methyl donor deficiency induces cardiomyopathy through altered methylation/acetylation of PGC-1α by PRMT1 and SIRT1

Cardiomyopathies occur by mechanisms that involve inherited and acquired metabolic disorders. Both folate and vitamin B12 deficiencies are associated with left ventricular dysfunction, but mechanisms that underlie these associations are not known. However, folate and vitamin B12 are methyl donors needed for the synthesis of S-adenosylmethionine, the substrate required for the activation by methylation of regulators of energy metabolism. We investigated the consequences of a diet lacking methyl donors in the myocardium of weaning rats from dams subjected to deficiency during gestation and lactation. Positron emission tomography (PET), microscope and metabolic examinations evidenced a myocardium hypertrophy, with cardiomyocyte enlargement, disturbed mitochondrial alignment, lipid droplets, decreased respiratory activity of complexes I and II and decreased S-adenosylmethionine:S-adenosylhomocysteine ratio. The increased concentrations of triglycerides and acylcarnitines were consistent with a deficit in fatty acid oxidation. These changes were explained by imbalanced acetylation/methylation of PGC-1α, through decreased expression of SIRT1 and PRMT1 and decreased S-adenosylmethionine:S-adenosylhomocysteine ratio, and by decreased expression of PPARα and ERRα. The main changes of the myocardium proteomic study were observed for proteins regulated by PGC-1α, PPARs and ERRα. These proteins, namely trifunctional enzyme subunit α-complex, short chain acylCoA dehydrogenase, acylCoA thioesterase 2, fatty acid binding protein-3, NADH dehydrogenase (ubiquinone) flavoprotein 2, NADH dehydrogenase (ubiquinone) 1α-subunit 10 and Hspd1 protein, are involved in fatty acid oxidation and mitochondrial respiration. In conclusion, the methyl donor deficiency produces detrimental effects on fatty acid oxidation and energy metabolism of myocardium through imbalanced methylation/acetylation of PGC-1α and decreased expression of PPARα and ERRα. These data are of pathogenetic relevance to perinatal cardiomyopathies.

Assessment of right ventricle volumes and function by cardiac MRI: quantification of the regional and global interobserver variability

Reproducibility of the manual assessment of right ventricle volumes by short-axis cine-MRI remains low and is often attributed to the difficulty in separating the right atrium from the ventricle. This study was designed to evaluate the regional interobserver variability of the right ventricle volume assessment to identify segmentation zones with the highest interobserver variability. Short-axis views of 90 right ventricles (30 hypertrophic, 30 dilated, and 30 normal) were acquired with 2D steady-state free precession sequences at 1.5 T and were manually segmented by two observers. The two segmentations were compared and the variations were quantified with a variation score based on the Hausdorff distance between the two segmentations and the interobserver 95% limits of concordance of the global volumes. The right ventricles were semiautomatically split into four subregions: apex, mid-ventricle, tricuspid zone, and infundibulum. These four subregions represented 11%, 34%, 36%, and 19% of the volume but, respectively, yielded variation scores of 8%, 16%, 42%, and 34%. The infundibulum yielded the highest interobserver regional variability although its variation score remained comparable to the tricuspid zone due to its lower volume. These results emphasize the importance of standardizing the segmentation of the infundibulum and the tricuspid zone to improve reproducibility.

Analysis of the relationship between interictal electrical source imaging and PET hypometabolism

The aim of this paper is to compare interictal EEG source localizations with statistical analysis of hypometabolisms in PET brain imaging. Both methods are currently used in the pre-surgical evaluation of drug-resistant partial epilepsy, but the relationship between electrical source localizations and hypometabolic areas has not been well defined yet. At the present time, these two methods have been performed on five patients in order to develop a comparative quantitative study with these first results which should be then extended to a larger patient database.

Re-assessment of chronic radio-induced tissue damage in a rat hindlimb model

Radiotherapy is successfully used to treat neoplastic lesions, but may adversely affect normal tissues within the irradiated volume. However, additional clinical and para-clinical data are required for a comprehensive understanding of the pathogenesis of this damage. We assessed a rat model using clinical records and medical imaging to gain a better understanding of irradiation-induced tissue damage. The hindlimbs of the rats in this model were irradiated with a single dose of 30 or 50 Gy. Sequential analysis was based on observation records of stage and planar scintigraphy. Additional radiography, radiohistology and histology studies were performed to detect histological alterations. All animals developed acute and late effects, with an increased severity after a dose of 50 Gy. The bone uptake of (99m)Tc-HDP was significantly decreased in a dose- and time-dependent manner. Histologically, significant tissue damage was observed. After the 50 Gy irradiation, the animals developed lesions characteristic of osteoradionecrosis (ORN). Radiographic and histological studies provided evidence of lytic bone lesions. Our rat model developed tissue damage characteristic of radiation injury after a single 30 Gy irradiation and tissue degeneration similar to that which occurs during human ORN after a 50 Gy irradiation. The development of this animal model is an essential step in exploring the pathogenesis of irradiation-induced tissue damage, and may be used to test the efficacy of new treatments.

Posterior glucose hypometabolism in Lafora disease: early and late FDG-PET assessment

Establishing an early diagnosis of Lafora disease (LD) is often challenging. We describe two cases of LD presenting as myoclonus and tonic-clonic seizures, initially suggesting idiopathic generalized epilepsy. The subsequent course of the disease was characterized by drug-resistant myoclonic epilepsy, cognitive decline, and visual symptoms, which oriented the diagnosis toward progressive myoclonic epilepsy and, more specifically, LD. Early in the evolution in the first case, and before histopathologic and genetic confirmation of LD in both cases, [18]Fluorodeoxyglucose positron emission tomography (FDG-PET) revealed posterior hypometabolism, consistent with the well-known posterior impairment in this disease. This suggests that FDG-PET could help to differentiate LD in early stages from other progressive myoclonic epilepsies, but confirmation is required by a longitudinal study of FDG-PET in progressive myoclonic epilepsy.

Intramyocardial Implantation of bone marrow-derived stem cells enhances perfusion in chronic myocardial infarction: dependency on initial perfusion depth and follow-up assessed by gated pinhole SPECT

Cell therapy-induced changes in the perfusion of areas of myocardial infarction (MI) remain unclear. This study investigated whether an original pinhole SPECT technique could be applied to a rat MI model to analyze local improvement in myocardial perfusion relating to engraftment sites of bone marrow-derived stem cells (BMSCs).

METHODS

Four-month-old MI rats were either untreated (n = 8) or treated (n = 10) by intramyocardial injection of (111)In-labeled BMSCs. Early distribution of (111)In-BMSCs within the MI target was evidenced by dual (111)In/(99m)Tc pinhole SPECT 48 h later. Myocardial perfusion was serially monitored by (99m)Tc-sestamibi pinhole gated SPECT up to 3 mo after transplantation.

RESULTS

Forty-eight hours after transplantation, (111)In-BMSCs were observed in all treated rats and in 18 of their 32 underperfused MI segments (<70% sestamibi uptake before transplantation). During the subsequent 3-mo follow-up, the perfusion of MI segments worsened in untreated rats (absolute change in sestamibi uptake, -3% +/- 3%; P < 0.05) but improved in treated rats (+4% +/- 7%; P < 0.05). This perfusion improvement was unrelated to the initial detection of (111)In-BMSCs (+2% +/- 6% in segments with (111)In-BMSCs vs. +5% +/- 7% in those without; not statistically significant) but was strongly associated with less severe perfusion defects before transplantation (+6% +/- 6% in segments with 60%-70% sestamibi uptake [n = 19] vs. -1% +/- 6% in those with <60% uptake [n = 13]; P = 0.003).

CONCLUSION

When BMSCs are injected within chronic MI, perfusion enhancement predominates in the MI areas showing a high enough residual perfusion before treatment but not in those of the initial cell engraftment, giving evidence of dependency on the perfusion and metabolic environment at implantation sites.

Resuscitation of severe but brief haemorrhagic shock with PFC in rabbits restores skeletal muscle oxygen delivery and does not alter skeletal muscle metabolism

Studies have demonstrated that perfluorocarbon (PFC) emulsions associated with hyperoxia improved whole body oxygen delivery during resuscitation of acute haemorrhagic shock (HS). Nevertheless the microcirculatory effects of PFC and the potential deleterious effects of hyperoxic reperfusion are still of concern. We investigated (i) the ability of a newly formulated, small sized and highly stable PFC emulsion to increase skeletal muscle oxygen delivery and (ii) the effect of hyperoxic reperfusion on skeletal muscle metabolism after a brief period of ischaemia using an original, microdialysis-based method that allowed simultaneous measurement tissue oxygen pressure (PtiO2) and interstitial lactate and pyruvate. These measurements were carried out in anaesthetised and ventilated (FiO2 = 1) rabbits subjected to acute HS (50% of blood volume withdrawal) and either resuscitated with a PFC emulsion diluted with a 5% albumin solution (16.2 g PFC per kg body weight) (n = 10) or with a modified fluid gelatin solution (Gelofusine) (n = 10). We found no difference between the two groups for the haemodynamic and haematological variables (except for the venous oxygen partial pressure). However, a significant difference was observed in the slope of the regression linear relationship exhibited between the mean arterial pressure (MAP) and the PtiO2, PFC group showing a much steeper slope than Gelofusine group. In addition, PtiO2 values increased linearly with decreasing haematocrit (Hct) values in PFC-resuscitated animals and decreased linearly with decreasing Hct values in Gelofusine-resuscitated animals. There were no differences between the two groups concerning the blood and interstitial lactate/pyruvate ratios suggesting no deleterious effect of hyperoxic resuscitation in skeletal muscle. In conclusion these results suggest that resuscitation of severe, but brief, HS with PFC increased skeletal muscle oxygen delivery without measurable deleterious effects.

[Association of Wolff-Parkinson-White syndrome with isolated non-compaction of the left ventricle: a case report]

The Wolff-Parkinson-White syndrome (WPW) may be associated with a number of cardiac pathologies, especially congenital disease, in 7.5 to 17% of cases. The authors report a rare association of the WPW syndrome with two Kent bundles, right and left septal, with non-compaction of the left ventricle in a 52 year old man. This was a chance finding during systematic echocardiography after ablation, and confirmed by cardiac MRI. The patient was asymptomatic.

Feasibility of in vivo dual-energy myocardial SPECT for monitoring the distribution of transplanted cells in relation to the infarction site

PURPOSE

Cell therapy using bone marrow mesenchymal stem cells (BMSCs) shows promise in the treatment of myocardial infarction (MI) but accurate cell delivery within MI areas remains critical. In the present study, we tested the feasibility of in vivo pinhole SPECT imaging for monitoring the sites of intramyocardial implanted BMSCs in relation to targeted MI areas in rats.

METHODS

BMSCs were labelled with (111)In-oxine and injected within the fibrotic areas of 3-month-old MI in ten rats. Two days later, dual (111)In/(99m)Tc-sestamibi pinhole SPECT was recorded for localisation of (111)In-BMSCs on a 15-segment left ventricular (LV) division. Additional (99m)Tc-sestamibi pinhole SPECT had been performed 1 month earlier and on the day before transplantation. In vitro counting on histological sections was used to validate the pinhole SPECT determination of (111)In-BMSC activity within LV segments.

RESULTS

The underperfused MI area (segments with <70% uptake) was stable between the (99m)Tc-sestamibi SPECT study recorded at 1 month (4.6+/-1.9 segments) and at 1 day (4.7+/-2.3 segments) before transplantation. (111)In-BMSCs were detected by dual-energy SPECT in 56 segments: 33 (59%) were underperfused MI segments but 23 (41%) were not (14 adjacent and nine remote segments). Finally, (111)In-labelled BMSCs were not detected in 14 out of the 47 (30%) underperfused MI segments.

CONCLUSION

When BMSCs are injected within MI areas in rats, sites of early cell retention do not always match the targeted MI areas. The dual-energy pinhole SPECT technique may be used for monitoring the sites of early retention of implanted BMSCs and the data obtained may have critical importance when analysing the effects of cardiac cell therapy.

EANM/ESC procedural guidelines for myocardial perfusion imaging in nuclear cardiology

The European procedural guidelines for radionuclide imaging of myocardial perfusion and viability are presented in 13 sections covering patient information, radiopharmaceuticals, injected activities and dosimetry, stress tests, imaging protocols and acquisition, quality control and reconstruction methods, gated studies and attenuation-scatter compensation, data analysis, reports and image display, and positron emission tomography. If the specific recommendations given could not be based on evidence from original, scientific studies, we tried to express this state-of-art. The guidelines are designed to assist in the practice of performing, interpreting and reporting myocardial perfusion SPET. The guidelines do not discuss clinical indications, benefits or drawbacks of radionuclide myocardial imaging compared to non-nuclear techniques, nor do they cover cost benefit or cost effectiveness.

Changes in First-Pass Interstitial Kinetics of DTPA in Myocardium Submitted to Low-Flow Ischemia

OBJECTIVES

This study aimed to determine the changes during ischemia in the myocardial first-pass kinetics of DTPA, an extracellular tracer that is currently used for assessing myocardial perfusion with magnetic resonance imaging (Magnevist).

MATERIALS AND METHODS

Using an indicator-dilution technique, first-pass kinetics of DTPA were compared between normoxia (n=11) and low-flow ischemia (n=11) in isolated rabbit hearts perfused with red blood cell-enhanced perfusate.

RESULTS

There was no difference between ischemia and normoxia in the interstitial extraction and clearance rates of DTPA. Interstitial distribution volume of DTPA was, however, lower in ischemia than in normoxia (in percent of myocardial volume: 15+/-11% vs 25+/-11%, P=0.02) as a result of a relationship with coronary flow (P<0.001).

CONCLUSIONS

During low-flow myocardial ischemia, DTPA kinetics are unchanged, except for the interstitial distribution volume that is decreased, presumably because of the shrinkage of extracellular fluid. These kinetic properties are favorable for detecting myocardial ischemia at rest with magnetic resonance imaging.

OSEM reconstruction, associated with temporal fourier and depth-dependant resolution recovery filtering, enhances results from sestamibi and 201Tl 16-interval gated SPECT

Gated SPECT recorded with 16 intervals determines left ventricular (LV) ejection fraction more accurately than does gated SPECT recorded with 8 intervals but produces higher image noise. This study aimed to assess the results from sestamibi and (201)Tl 16-interval gated SPECT when both signal-to-noise ratio and spatial resolution were enhanced with an original method of reconstruction.

METHODS

Forty patients with coronary artery disease underwent (201)Tl and sestamibi 16-interval gated SPECT and, to be used as a reference, cardiac MRI. Assessments of global and regional LV function provided by ordered-subsets expectation maximization (OSEM) with depth-dependant resolution recovery and temporal Fourier filtering were compared with those from conventional filtered backprojection (FBP) previously optimized by screening various filter frequencies and various temporal smoothing levels.

RESULTS

For both tracers, LV ejection fraction was determined best when the association of OSEM with depth-dependant resolution recovery was used alone, with temporal Fourier filtering, or with a slight 2-frame temporal smoothing: Mean absolute values of relative errors ranged from 3.2% to 3.6% (4.0%-7.9% for FBP), and coefficient correlation ranged from 0.91 to 0.93 (0.70-0.91 for FBP). Among these 3 reconstruction methods, the association of OSEM with depth-dependant resolution recovery with temporal Fourier filtering provided the highest signal-to-noise ratio, with mean increases of 54% for sestamibi and 80% for (201)Tl when compared with FBP, and the best analysis of segmental contractility, with exact agreement rates with MRI being 73% for (201)Tl and 79% for sestamibi.

CONCLUSION

OSEM associated with temporal Fourier filtering and depth-dependant resolution recovery filtering enhances the LV function assessment provided by sestamibi and (201)Tl 16-interval gated SPECT and dramatically reduces image noise, a property that enhances and facilitates image interpretation.