scholarly journals Ex vivo Validation of Noninvasive Epicardial and Endocardial Repolarization Mapping

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeanne G. van der Waal ◽  
Veronique M. F. Meijborg ◽  
Charly N. W. Belterman ◽  
Geert J. Streekstra ◽  
Thom F. Oostendorp ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Absolute Difference ◽  
Noninvasive Estimation ◽  
Equivalent Dipole ◽  
Surface Ecg ◽  
Selective Perfusion ◽  
Temporal And Spatial ◽  
Detection And Localization ◽  
Perfused Hearts ◽  
Unipolar Electrograms

Background: The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity.Methods: In four Langendorff-perfused pig hearts, we simultaneously recorded unipolar electrograms from plunge needles and pseudo-ECGs from a volume-conducting container equipped with 61 electrodes. The RTs were computed from the ECGs during atrial and ventricular pacing and compared with those measured from the local unipolar electrograms. Regional RT prolongation (cooling) or shortening (pinacidil) was achieved by selective perfusion of the left anterior descending artery (LAD) region.Results: The differences between the computed and measured RTs were 19.0 ± 17.8 and 18.6 ± 13.7 ms for atrial and ventricular paced beats, respectively. The region of artificially delayed or shortened repolarization was correctly identified, with minimum/maximum RT roughly in the center of the region in three hearts. In one heart, the reconstructed region was shifted by ~2.5 cm. The total absolute difference between the measured and calculated RTs for all analyzed patterns in selectively perfused hearts (n = 5) was 39.6 ± 27.1 ms.Conclusion: The noninvasive ECG repolarization imaging using the EDL method of atrial and ventricular paced beats allows adequate quantitative reconstruction of regions of altered repolarization.

Treatment of type 2 diabetic db/db mice with a novel PPARγ agonist improves cardiac metabolism but not contractile function

2004 ◽  
Vol 286 (3) ◽  
pp. E449-E455 ◽  
Author(s):  
Andrew N. Carley ◽  
Lisa M. Semeniuk ◽  
Yakhin Shimoni ◽  
Ellen Aasum ◽  
Terje S. Larsen ◽  
...  
Keyword(s):  
Contractile Function ◽  
Ex Vivo ◽  
Metabolic Changes ◽  
Pparγ Agonist ◽  
Perfused Hearts ◽  
Type 2 Diabetic ◽  
Contractile Performance ◽  
Exogenous Substrates

Hearts from insulin-resistant type 2 diabetic db/db mice exhibit features of a diabetic cardiomyopathy with altered metabolism of exogenous substrates and reduced contractile performance. Therefore, the effect of chronic oral administration of 2-(2-(4-phenoxy-2-propylphenoxy)ethyl)indole-5-acetic acid (COOH), a novel ligand for peroxisome proliferator-activated receptor-γ that produces insulin sensitization, to db/db mice (30 mg/kg for 6 wk) on cardiac function was assessed. COOH treatment reduced blood glucose from 27 mM in untreated db/db mice to a normal level of 10 mM. Insulin-stimulated glucose uptake was enhanced in cardiomyocytes from COOH-treated db/db hearts. Working perfused hearts from COOH-treated db/db mice demonstrated metabolic changes with enhanced glucose oxidation and decreased palmitate oxidation. However, COOH treatment did not improve contractile performance assessed with ex vivo perfused hearts and in vivo by echocardiography. The reduced outward K+ currents in diabetic cardiomyocytes were still attenuated after COOH. Metabolic changes in COOH-treated db/db hearts are most likely indirect, secondary to changes in supply of exogenous substrates in vivo and insulin sensitization.

scholarly journals STAT subtype specificity and ischemic preconditioning in mice: is STAT-3 enough?

2011 ◽  
Vol 300 (2) ◽  
pp. H522-H526 ◽  
Author(s):  
Michael D. Goodman ◽  
Sheryl E. Koch ◽  
Muhammad R. Afzal ◽  
Karyn L. Butler
Keyword(s):  
Ischemic Preconditioning ◽  
Ischemia Reperfusion Injury ◽  
Contractile Function ◽  
Ex Vivo ◽  
Ischemia Reperfusion ◽  
Cardiac Performance ◽  
Subtype Specificity ◽  
Developed Pressure ◽  
Perfused Hearts

The role of other STAT subtypes in conferring ischemic tolerance is unclear. We hypothesized that in STAT-3 deletion alternative STAT subtypes would protect myocardial function against ischemia-reperfusion injury. Wild-type (WT) male C57BL/6 mice or mice with cardiomyocyte STAT-3 knockout (KO) underwent baseline echocardiography. Langendorff-perfused hearts underwent ischemic preconditioning (IPC) or no IPC before ischemia-reperfusion. Following ex vivo perfusion, hearts were analyzed for STAT-5 and -6 phosphorylation by Western blot analysis of nuclear fractions. Echocardiography and postequilibration cardiac performance revealed no differences in cardiac function between WT and KO hearts. Phosphorylated STAT-5 and -6 expression was similar in WT and KO hearts before perfusion. Contractile function in WT and KO hearts was significantly impaired following ischemia-reperfusion in the absence of IPC. In WT hearts, IPC significantly improved the recovery of the maximum first derivative of developed pressure (+dP/d tmax) compared with that in hearts without IPC. IPC more effectively improved end-reperfusion dP/d tmax in WT hearts compared with KO hearts. Preconditioned and nonpreconditioned KO hearts exhibited increased phosphorylated STAT-5 and -6 expression compared with WT hearts. The increased subtype activation did not improve the efficacy of IPC in KO hearts. In conclusion, baseline cardiac performance is preserved in hearts with cardiac-restricted STAT-3 deletion. STAT-3 deletion attenuates preconditioning and is not associated with a compensatory upregulation of STAT-5 and -6 subtypes. The activation of STAT-5 and -6 in KO hearts following ischemic challenge does not provide functional compensation for the loss of STAT-3. JAK-STAT signaling via STAT-3 is essential for effective IPC.

scholarly journals Mitochondrial transplantation for myocardial protection in diabetic hearts

2019 ◽  
Vol 57 (5) ◽  
pp. 836-845 ◽  
Author(s):  
Ilias P Doulamis ◽  
Alvise Guariento ◽  
Thomas Duignan ◽  
Arzoo Orfany ◽  
Takashi Kido ◽  
...  
Keyword(s):  
Diastolic Pressure ◽  
Ex Vivo ◽  
Left Ventricular ◽  
Diabetic Rat ◽  
Ischaemia Reperfusion Injury ◽  
Global Ischaemia ◽  
Aortic Cannula ◽  
Developed Pressure ◽  
Perfused Hearts

Abstract OBJECTIVES Type 2 diabetes causes mitochondrial dysfunction, which increases myocardial susceptibility to ischaemia–reperfusion injury. We investigated the efficacy of transplantation of mitochondria isolated from diabetic or non-diabetic donors in providing cardioprotection from warm global ischaemia and reperfusion in the diabetic rat heart. METHODS Ex vivo perfused hearts from Zucker diabetic fatty (ZDF fa/fa) rats (n = 6 per group) were subjected to 30 min of warm global ischaemia and 120 min reperfusion. Immediately prior to reperfusion, vehicle alone (VEH) or vehicle containing mitochondria isolated from either ZDF (MTZDF) or non-diabetic Zucker lean (ZL +/?) (MTZL) skeletal muscle were delivered to the coronary arteries via the aortic cannula. RESULTS Following 30-min global ischaemia and 120-min reperfusion, left ventricular developed pressure was significantly increased in MTZDF and MTZL groups compared to VEH group (MTZDF: 92.8 ± 5.2 mmHg vs MTZL: 110.7 ± 2.4 mmHg vs VEH: 44.3 ± 5.9 mmHg; P < 0.01 each); and left ventricular end-diastolic pressure was significantly decreased (MTZDF 12.1 ± 1.3 mmHg vs MTZL 8.6 ± 0.8 mmHg vs VEH: 18.6 ± 1.5 mmHg; P = 0.016 for MTZDF vs VEH and P < 0.01 for MTZL vs VEH). Total tissue ATP content was significantly increased in both MT groups compared to VEH group (MTZDF: 18.9 ± 1.5 mmol/mg protein/mg tissue vs MTZL: 28.1 ± 2.3 mmol/mg protein/mg tissue vs VEH: 13.1 ± 0.5 mmol/mg protein/mg tissue; P = 0.018 for MTZDF vs VEH and P < 0.01 for MTZL vs VEH). Infarct size was significantly decreased in the MT groups (MTZDF: 11.8 ± 0.7% vs MTZL: 9.9 ± 0.5% vs VEH: 52.0 ± 1.4%; P < 0.01 each). CONCLUSIONS Mitochondrial transplantation significantly enhances post-ischaemic myocardial functional recovery and significantly decreases myocellular injury in the diabetic heart.

Including Vibration Characteristics Within Compressive Sensing Formulations for Structural Monitoring of Beams

2017 ◽  
Author(s):  
Vaahini Ganesan ◽  
Tuhin K. Das ◽  
Jeffrey L. Kauffman ◽  
Nazanin Rahnavard
Keyword(s):  
Boundary Conditions ◽  
Compressive Sensing ◽  
Continuous Monitoring ◽  
Structural Changes ◽  
Vibration Monitoring ◽  
High Data ◽  
Data Volume ◽  
Spatial Domains ◽  
Temporal And Spatial ◽  
Detection And Localization

Vibration-based monitoring of mechanical structures often involves continuous monitoring that result in high data volume and instrumentation with a large array of sensors. Previously, we have shown that Compressive Sensing (CS)-based vibration monitoring can significantly reduce both volume of data and number of sensors in temporal and spatial domains respectively. In this work, further analysis of CS-based detection and localization of structural changes is presented. Incorporating damping and noise handling in the CS algorithm improved its performance for frequency recovery. CS-based reconstruction of deflection shape of beams with fixed boundary conditions is addressed. Formulation of suitable bases with improved conditioning is explored. Restricting hyperbolic terms to lower frequencies in the basis functions improves reconstruction. An alternative is to generate an augmented basis that combines harmonic and hyperbolic terms. Incorporating known boundary conditions into the CS problem is studied.

scholarly journals Noninvasive assessment of local myocardium repolarization changes using high-resolution surface ECG mapping

2007 ◽  
pp. S133-S141
Author(s):  
M Tyšler ◽  
P Kneppo ◽  
M Turzová ◽  
J Švehlíková ◽  
S Karas ◽  
...  
Keyword(s):  
Simulated Data ◽  
Coronary Intervention ◽  
Dipole Orientation ◽  
Unsuccessful Treatment ◽  
Equivalent Dipole ◽  
Mapping System ◽  
Surface Ecg ◽  
Volume Conductor Model ◽  
Body Surface Potential ◽  
Measuring Unit

A method using body surface potential maps for assessment of myocardium lesions with changed repolarization is presented and suitable mapping system is introduced. Differences between normal and altered QRST integral maps together with torso volume conductor model were used to determine the equivalent dipole representing the lesion. Performance of the method was studied on simulated data. Changed repolarization was modeled by shortening of myocyte action potentials in regions typical for stenosis of the main coronary arteries. The equivalent dipole estimated the positions of small lesions with a mean error of 9+/-4 mm (17+/-14 mm for larger transmural lesions). The subepicardial or subendocardial character of the lesions was reflected in the dipole orientation. Tests of the method on patients after myocardial infarction that underwent coronary intervention on a single coronary vessel showed that in 7 of 8 successfully treated patients the dipole position matched well with the treated vessel. A small dipole moment in another patient indicated unsuccessful treatment. The method was implemented in a new 128-channel mapping system. Its active electrodes, battery powered measuring unit and optical computer interface help to minimize noise in ECG and guarantee patient's safety. The results suggest that the method and mapping system offer useful tools for noninvasive identification of local repolarization changes in the myocardium.

scholarly journals Semi-intact ex vivo approach to investigate spinal somatosensory circuits

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Junichi Hachisuka ◽  
Kyle M Baumbauer ◽  
Yu Omori ◽  
Lindsey M Snyder ◽  
H Richard Koerber ◽  
...  
Keyword(s):  
Neural Circuits ◽  
Ex Vivo ◽  
Projection Neurons ◽  
New Approach ◽  
Spinal Interneurons ◽  
Somatosensory Input ◽  
Health And Disease ◽  
Output Neurons ◽  
Temporal And Spatial ◽  
Ex Vivo Approach

The somatosensory input that gives rise to the perceptions of pain, itch, cold and heat are initially integrated in the superficial dorsal horn of the spinal cord. Here, we describe a new approach to investigate these neural circuits in mouse. This semi-intact somatosensory preparation enables recording from spinal output neurons, while precisely controlling somatosensory input, and simultaneously manipulating specific populations of spinal interneurons. Our findings suggest that spinal interneurons show distinct temporal and spatial tuning properties. We also show that modality selectivity — mechanical, heat and cold — can be assessed in both retrogradely labeled spinoparabrachial projection neurons and genetically labeled spinal interneurons. Finally, we demonstrate that interneuron connectivity can be determined via optogenetic activation of specific interneuron subtypes. This new approach may facilitate key conceptual advances in our understanding of the spinal somatosensory circuits in health and disease.

The Noninvasive Electrical Mapping of Reanimated Large Mammalian Hearts

2020 ◽  
Author(s):  
Renee C. Brigham ◽  
David A. Ramirez ◽  
Tinen L. Iles ◽  
Paul A. Iaizzo
Keyword(s):  
Ex Vivo ◽  
Epicardial Mapping ◽  
Critical Data ◽  
Non Invasive ◽  
Mapping System ◽  
Set Up ◽  
Perfused Hearts ◽  
Mapping Systems

Abstract Electroanatomical mapping systems are being utilized clinically for locating arrhythmias within a given patient’s heart. Today, employed endocardial mapping systems are invasive and require extensive set-up time. Epicardial mapping systems, like CardioInsight™ from Medtronic, are non-invasive but require co-registration of electrodes to the heart, e.g. via a required Computed Tomography (CT) scan. This system has been used both clinically and in several laboratories in situ. The difficulties with in vitro uses are that the ex vivo perfused hearts lack an associated thoracic cavity, resulting in the possibility of inconsistent placement of electrodes, and poor conduction of epicardial signals. We are developing in our laboratory means to use the CardioInsight™ system on reanimated large mammalian hearts. Preliminary studies were conducted on swine hearts, but this system could be also be utilized with reanimated human hearts, making this research even more translatable. The use of this epicardial mapping system will allow for critical observations during pacing or ablation experiments and for collecting critical data for computational modeling.

Prolonged support of working rabbit hearts using Fluosol-43 or erythrocyte media

1987 ◽  
Vol 252 (2) ◽  
pp. H349-H359 ◽  
Author(s):  
L. D. Segel ◽  
J. L. Ensunsa ◽  
W. A. Boyle
Keyword(s):  
Coronary Flow ◽  
Ex Vivo ◽  
Systolic Pressure ◽  
Pressure Rise ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Aortic Flow ◽  
Stable Function ◽  
Pressure Peak ◽  
Perfused Hearts

We compared the perfluorochemical emulsion Fluosol-43 and an erythrocyte-based solution as support media for ex vivo working rabbit hearts functioning with a physiological workload. Both groups of hearts (n = 5/group) exhibited stable function (left ventricular peak systolic pressure, peak rates of left ventricular pressure rise and relaxation, aortic flow, peak aortic flow rate, stroke work, and peak power) for the first 6 h of perfusion. Coronary flow, coronary venous O2 content, and O2 supply-to-demand ratio declined similarly in both groups during the first 6 h. Both groups of hearts preferentially utilized pyruvate to glucose. The Fluosol-43-perfused hearts had higher heart rate, left ventricular peak systolic pressure, peak rate of left ventricular pressure rise, aortic flow, coronary flow, and myocardial O2 consumption compared with the erythrocyte-perfused hearts. The Fluosol-43 hearts produced more lactate and released more creatine phosphokinase than did the erythrocyte-perfused hearts, but the rates were low and constant throughout perfusion, indicating that the hearts were not progressively ischemic. After the first 6 h, function of the Fluosol-43 hearts declined, resulting in their earlier failure compared with the erythrocyte-perfused hearts. The data indicate that Fluosol-43 had sufficient O2- carrying capacity to support stable function of a rabbit heart at a physiological workload for 6 h, and differences in function and ex vivo longevity of the two groups of hearts suggested that a component or contaminant of Fluosol-43 altered sarcolemmal function and/or that a component needed for membrane integrity was lacking in the Fluosol-43 perfusate.

Cardiac function of the diabetic renovascular hypertensive rat: effects of insulin and thyroid hormone treatment

1991 ◽  
Vol 69 (3) ◽  
pp. 346-354 ◽  
Author(s):  
Robert L. Rodgers ◽  
Amy J. Davidoff ◽  
Mark J. Mariani
Keyword(s):  
Insulin Therapy ◽  
Diabetic Cardiomyopathy ◽  
Ex Vivo ◽  
Heart Function ◽  
Left Ventricular ◽  
Left Renal Artery ◽  
Hypertensive Rats ◽  
Heart Performance ◽  
Perfused Hearts

The influences of hypertension and hypothyroidism on diabetic cardiomyopathy are not clear. We studied this problem further by characterizing the effects of chronic triiodothyronine (T3) treatment on cardiac performance of diabetic renovascular hypertensive (RVH) rats. Hypertension was effected by clipping the left renal artery of Wistar–Kyoto (WKY) rats, and diabetes was induced 2 weeks later by streptozotocin (STZ; 55 mg/kg i.v.). The WKY strain was selected because it is relatively resistant to the cardiodepressant effects of diabetes, so that the influence of superimposed hypertension would be more apparent. Performance of working Krebs–Henseleit buffer perfused hearts was quantified by measuring left ventricular pressure and flow characteristics. The results showed that renovascular clipping caused a marked hypertension and left ventricular hypertrophy (LVH) but had no effect on perfused heart performance after 10 weeks. They also showed that diabetes during the final 8 weeks (i) caused a marked impairment in the performance of perfused hearts ex vivo of hypertensive rats but had no measurable effect in the normotensive WKY, (ii) had no effect on arterial pressure of either the normotensive or the hypertensive rats but reduced heart rate of hypertensive animals in vivo, and (iii) caused equivalent hyperglycemia, hypoinsulinemia, and hypothyroidism (depressed serum T3 and T4 levels) of hypertensive and normotensive rats. Treatment of diabetic RVH rats with T3 (10 μg∙kg−1∙day−1) in vivo was nearly as effective as insulin therapy (10 U∙kg−1∙day−1) in preventing the cardiac dysfunction ex vivo and was as effective as insulin therapy in preventing the bradycardia in vivo and the decline in serum T3 levels, even though it intensified the hyperglycemia and body weight loss. The results provide support for a synergistic effect of diabetes and hypertension on heart function. They also add support to the hypothesis that attendant hypothyroidism contributes significantly to diabetic cardiomyopathy in the hypertensive rat.Key words: heart performance, triiodothyronine, hypothyroidism, cardiomyopathy.

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