Effects of heart isolation, voltage-sensitive dye, and electromechanical uncoupling agents on ventricular fibrillation

2003 ◽  
Vol 284 (5) ◽  
pp. H1818-H1826 ◽  
Author(s):  
Hao Qin ◽  
Matthew W. Kay ◽  
Nipon Chattipakorn ◽  
David T. Redden ◽  
Raymond E. Ideker ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Pattern Analysis ◽  
Electrode Array ◽  
Left Ventricular ◽  
Control Data ◽  
Voltage Sensitive Dye ◽  
Activation Patterns ◽  
Langendorff Perfusion ◽  
Perfusion Apparatus ◽  
Diacetyl Monoxime

We tested whether the interventions typically required for optical mapping affect activation patterns during ventricular fibrillation (VF). A 21 × 24 unipolar electrode array (1.5 mm spacing) was sutured to the left ventricular epicardium of 16 anesthetized pigs, and four episodes of electrically induced VF (30-s duration) were recorded. The hearts were then rapidly excised and connected to a Langendorff perfusion apparatus. Four of the hearts were controls, in which 24 additional VF episodes were then mapped. In the remaining 12 hearts, four VF episodes were mapped after isolation, four more episodes were mapped after exposure to the voltage-sensitive dye di-4-ANEPPS, and six more episodes were mapped after exposure to the electromechanical uncoupling agents diacetyl monoxime (DAM; 20 mmol/l, n = 6) or cytochalasin D (CytoD; 10 μmol/l, n = 6). VF episodes were separated by 4 min. VF activation patterns were quantified using custom pattern analysis algorithms. From comparisons with time-corrected control data, all interventions significantly changed VF patterns. Most changes were broadly consistent with slowing and regularization due to loss of excitability. Heart isolation had the largest effect on VF patterns, followed by CytoD, DAM, and dye.

Evolution of activation patterns during long-duration ventricular fibrillation in dogs

2004 ◽  
Vol 286 (3) ◽  
pp. H1193-H1200 ◽  
Author(s):  
Jian Huang ◽  
Jack M. Rogers ◽  
Cheryl R. Killingsworth ◽  
Karan P. Singh ◽  
William M. Smith ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Sudden Cardiac Arrest ◽  
Quantitative Description ◽  
Electrode Array ◽  
Stage Iv ◽  
Peak Frequency ◽  
Stage Iii ◽  
Activation Patterns ◽  
Voltage Change ◽  
Clinical Consequences

Although resuscitation for sudden cardiac arrest attempts are frequently not instituted for several minutes after the onset of ventricular fibrillation (VF), previous mapping studies have examined only the first 40 s of VF or have involved isolated perfused hearts that did not become ischemic during VF. We applied quantitative pattern analysis to mapping data throughout the first 10 min of VF acquired from a 21 × 24 unipolar electrode array located on the ventricular epicardium of six open-chest dogs. The following twelve descriptors were continuously quantified: 1) number of wavefronts, 2) incidence of reentry, 3) wavefront propagation velocity, 4) incidence of breakthrough/focus, 5) incidence of block, 6) mean area activated by the wavefronts, 7) wavefront fractionations, 8) wavefront collisions, 9) multiplicity index, 10) repeatability, 11) negative peak rate of voltage change, and 12) peak frequency of activation. Cluster analysis of these descriptors divided VF into five stages ( stages i– v). The values of most descriptors (except block and breakthrough incidence) increased during stage i (1–11 s after VF induction) and maintained high values with rapid dynamic fluctuations during stage ii (12–62 s). Descriptors changed quickly to values indicating greater organization during stage iii (63–86 s), decreased steadily during stage iv (87–310 s), and approached zero during stage v (311–600 s). There was a high incidence of reentry just before, during, and after stage iii. In conclusion, during the first 10 min, VF can be divided into five stages according to the evolution of electrophysiological characteristics. All of the parameters show a rapid deterioration during VF, except for a temporary reversal ∼1 min after induction when activation briefly became more organized. Thus a quantitative description of activation does not uniformly decrease as VF progresses, but undergo rapid changes and exhibit a brief interval of increased organization after ∼1 min of VF. Further studies are warranted to determine whether these changes, particularly the increased organization of stage iii, have clinical consequences, such as an alteration in defibrillation efficacy.

scholarly journals Improved cardiac protection with Sabax cardioplegia in Langendorff isolated rat hearts

2014 ◽  
Vol 60 (6) ◽  
pp. 254-259
Author(s):  
M. Perian ◽  
M. Mărginean ◽  
D. Dobreanu ◽  
Alina Scridon
Keyword(s):  
Myocardial Protection ◽  
Myocardial Injury ◽  
Left Ventricular ◽  
Mechanical Activity ◽  
Cardioplegic Arrest ◽  
Rat Hearts ◽  
Langendorff Perfusion ◽  
Perfusion Apparatus ◽  
Solution Methods ◽  
Male Wistar Rats

Abstract Objective: Cardioplegia is an important step to facilitate cardiac surgery while limiting intraoperative myocardial injury. Although recent advances in cardioplegic arrest methods have significantly contributed to better postoperative outcomes, there is still controversy regarding the optimal composition and temperature of the cardioplegic solution. Accordingly, we aimed to assess whether cold or lukewarm Sabax cardioplegia offer improved myocardial protection compared with the classical Krebs-Henseleit solution. Methods: The hearts of 40 male Wistar rats were isolated and submitted to constant-flow retrograde perfusion using a Langendorff perfusion apparatus. The hearts were randomly assigned to cold Krebs-Henseleit (K-H), cold Sabax, or lukewarm Sabax cardioplegia. The ECG, heart rates, and left ventricular systolic pressures (LVSP) were recorded pre- and post-cardioplegia. The time needed for cardioplegia induction and post-cardioplegia recovery were also noted. Results: Both cold and lukewarm Sabax cardioplegia insured faster induction and faster recovery following isothermic reperfusion compared to the standard K-H solution (both p< 0.01). With K-H cardioplegia, the hearts presented a 21.7% force loss after reperfusion (p< 0.001), whilst Sabax cardioplegia was associated with a slight increase in ventricular mechanical activity (3% LVSP increase with lukewarm Sabax cardioplegia, p< 0.001 and 2% LVSP increase with cold Sabax cardioplegia, p = 0.02). With Sabax cardioplegia the hearts displayed considerably less major arrhythmic events and presented less significant bradycardia. Conclusions: The present data suggest that Sabax cardioplegia may be superior to the classical cold crystalloid K-H solution in preserving mechanical activity of the heart and may provide superior protection against major arrhythmias.

Effects of diacetyl monoxime and cytochalasin D on ventricular fibrillation in swine right ventricles

2001 ◽  
Vol 280 (6) ◽  
pp. H2689-H2696 ◽  
Author(s):  
Moon-Hyoung Lee ◽  
Shien-Fong Lin ◽  
Toshihiko Ohara ◽  
Chikaya Omichi ◽  
Yuji Okuyama ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Ventricular Fibrillation ◽  
Action Potential Duration ◽  
Action Potentials ◽  
Optical Mapping ◽  
Cytochalasin D ◽  
Wave Fronts ◽  
Activation Patterns ◽  
Restitution Curve ◽  
Diacetyl Monoxime

Whether or not the excitation-contraction (E-C) uncoupler diacetyl monoxime (DAM) and cytochalacin D (Cyto D) alter the ventricular fibrillation (VF) activation patterns is unclear. We recorded single cell action potentials and performed optical mapping in isolated perfused swine right ventricles (RV) at different concentrations of DAM and Cyto D. Increasing the concentration of DAM results in progressively shortened action potential duration (APD) measured to 90% repolarization, reduced the slope of the APD restitition curve, decreased Kolmogorov-Sinai entropy, and reduced the number of VF wave fronts. In all RVs, 15–20 mmol/l DAM converted VF to ventricular tachycardia (VT). The VF could be reinduced after the DAM was washed out. In comparison, Cyto D (10–40 μmol/l) has no effects on APD restitution curve or the dynamics of VF. The effects of DAM on VF are associated with a reduced number of wave fronts and dynamic complexities in VF. These results are compatible with the restitution hypothesis of VF and suggest that DAM may be unsuitable as an E-C uncoupler for optical mapping studies of VF in the swine RVs.

Management of Ventricular Fibrillation during Acute Myocardial Infarction

1984 ◽  
Vol 23 (04) ◽  
pp. 209-213
Author(s):  
B. J. Northover
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Ventricular Fibrillation ◽  
Coronary Care Unit ◽  
Patient Survival ◽  
Left Ventricular ◽  
Ventricular Failure ◽  
Before And After ◽  
Coronary Care ◽  
The Creation

SummaryAnalysis of electrocardiograms tape-recorded from patients admitted to hospital with acute myocardial infarction revealed that the pattern of ventricular extrasystolic activity was not significantly different among those who subsequently developed ventricular fibrillation and those who did not. Episodes of ventricular fibrillation occurred predominantly within 4 hours from the start of infarction. Patients were 3 times less likely to survive an episode of ventricular fibrillation if they also had left ventricular failure than if this feature was absent. Management of episodes of ventricular fibrillation was compared in patients before and after the creation of a specially staffed and equipped coronary care unit. The success of electric shock as a treatment for ventricular fibrillation was similar before and after the creation of the coronary care unit. An attempt was made to determine which features in the management of ventricular fibrillation in this and in previously published series were associated with patient survival.

scholarly journals Glycolytic inhibition causes spontaneous ventricular fibrillation in aged hearts

2011 ◽  
Vol 301 (1) ◽  
pp. H180-H191 ◽  
Author(s):  
Norishige Morita ◽  
Jong-Hwan Lee ◽  
Aneesh Bapat ◽  
Michael C. Fishbein ◽  
William J. Mandel ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Connexin 43 ◽  
Left Ventricular ◽  
Triggered Activity ◽  
Adult Rat ◽  
Rat Hearts ◽  
Intracellular Calcium Ion ◽  
Dependent Protein ◽  
Isolated Cardiac Myocytes ◽  
Delayed Afterdepolarizations

Selective glycolytic inhibition (GI) promotes electromechanical alternans and triggered beats in isolated cardiac myocytes. We sought to determine whether GI promotes triggered activity by early afterdepolarization (EAD) or delayed afterdepolarizations in intact hearts isolated from adult and aged rats. Dual voltage and intracellular calcium ion (Cai2+) fluorescent optical maps and single cell glass microelectrode recordings were made from the left ventricular (LV) epicardium of isolated Langendorff-perfused adult (∼4 mo) and aged (∼24 mo) rat hearts. GI was induced by replacing glucose with 10 mM pyruvate in oxygenated Tyrode's. Within 20 min, GI slowed Cai2+ transient decline rate and shortened action potential duration in both groups. These changes were associated with ventricular fibrillation (VF) in the aged hearts (64 out of 66) but not in adult hearts (0 out of 18; P < 0.001). VF was preceded by a transient period of focal ventricular tachycardia caused by EAD-mediated triggered activity leading to VF within seconds. The VF was suppressed by the ATP-sensitive K (KATP) channel blocker glibenclamide (1 μM) but not (0 out of 7) by mitochondrial KATP block. The Ca-calmodulin-dependent protein kinase II (CaMKII) blocker KN-93 (1 μM) prevented GI-mediated VF ( P < 0.05). Block of Na-Ca exchanger (NCX) by SEA0400 (2 μM) prevented GI-mediated VF (3 out of 6), provided significant bradycardia did not occur. Aged hearts had significantly greater LV fibrosis and reduced connexin 43 than adult hearts ( P < 0.05). We conclude that in aged fibrotic unlike in adult rat hearts, GI promotes EADs, triggered activity, and VF by activation of KATP channels CaMKII and NCX.

Ventricular Fibrillation After Release of an Aortic Cross-Clamp in Valvular Surgery: Independent Risk Factors, Outcomes, and Incidence from Access Routes

2021 ◽  
Author(s):  
Weichao LI ◽  
heng li ◽  
Jianping Gong ◽  
Weihua Liu ◽  
BaoJun Fu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Ventricular Fibrillation ◽  
Clinical Outcomes ◽  
Valve Replacement ◽  
Smoking Status ◽  
Left Ventricular ◽  
Aortic Cross Clamp ◽  
Valvular Surgery ◽  
Htk Solution ◽  
Independent Risk Factors

Abstract Background Predictors and clinical outcomes of VF-ACC and the relative VF-ACC incidence with various access routes have not been well documented. This study aimed to identify predictors, clinical outcomes, and relative incidences of ventricular fibrillation after the release of an aortic cross-clamp (VF-ACC) with various access routes in valvular surgery.Patients and methods In this single-center and retrospective cohort study, we screened 228 consecutive patients undergoing valve surgery, and a total of 119 patients were included in the study. The primary outcomes were the relative incidence and predictors of VF-ACC with access routes, and secondary endpoints included effects of VF-ACC on 30-day mortality, perioperative ventricular arrhythmias (VAs), and heart failure with ejection fraction < 50% (HFEF < 50%).Results VF-ACC incidence varied on the basis of access routes. VF-ACC occurred in 58.3% of patients with aortic valve replacement via transverse aortotomy (TAo-AVR), in 48.6% of patients with aortic and mitral replacements via transseptal and transverse aortotomy access (TSAo-MAVR), and in 20% of patients with mitral valve replacement via transseptal access (TS-MVR). Seven independent risk factors were identified: HTK solution (AOR: 4.90, p = 0.002), smoking status (AOR: 6.30, p = 0.001), cerebrovascular disease (CBD) [(AOR: 7.08, p = 0.022)], regional wall motion abnormality (RWMA) [(AOR: 8.33, p < 0.001)], perioperative VAs (AOR: 4.85, p = 0.001), HFEF < 50% (AOR: 5.66, p = 0.002), and left ventricular mass index (LVMI) [(AOR: 0.962, CI: 0.941–0.984)].Conclusions VF-ACC was the most common in TAo-AVR and the least common in TS-MVR. HTK solution, smoking status, CBD, perioperative VAs, HFEF < 50%, and RWMA were associated with an increased risk of VF-ACC, and low LVMI acted as a protective factor. Patients with VF-ACC commonly experienced perioperative VAs or HFEFs < 50%.Clinical trial registration: ChiCTR2100050961.

scholarly journals Fontan-Like Hemodynamics Complicated With Ventricular Fibrillation During Left Ventricular Assist Device Support

2016 ◽  
Vol 57 (4) ◽  
pp. 515-518 ◽  
Author(s):  
Teruhiko Imamura ◽  
Koichiro Kinugawa ◽  
Daisuke Nitta ◽  
Osamu Kinoshita ◽  
Kan Nawata ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Assist Device ◽  
Ventricular Assist ◽  
Left Ventricular Assist

scholarly journals The Panoramic ECAP Method: estimating patient-specific patterns of current spread and neural health in cochlear implant users

2020 ◽  
Author(s):  
Charlotte Garcia ◽  
Tobias Goehring ◽  
Stefano Cosentino ◽  
Richard E Turner ◽  
John M. Deeks ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Significant Negative Correlation ◽  
Patient Specific ◽  
Clinical Settings ◽  
Neural Activation ◽  
Activation Patterns ◽  
Current Spread ◽  
Compound Action Potentials ◽  
In Cis

The knowledge of patient-specific neural excitation patterns from cochlear implants can provide important information for optimising efficacy and improving speech perception outcomes. The Panoramic ECAP (or ‘PECAP’) method (Cosentino, et al., 2015) uses forward-masked electrically evoked compound action potentials (ECAPs) to estimate neural activation patterns of cochlear implant (CI) stimulation. The algorithm requires ECAPs be measured for loudness-balanced stimuli from all combinations of probe and masker electrodes, and takes advantage of ECAP amplitudes being a result of the overlapping excitatory areas of both probes and maskers. Here we present an improved version of the PECAP algorithm that imposes biologically realistic constraints on the solution and produces separate estimates of current spread and neural health along the length of the electrode array. The algorithm was evaluated for reliability and accuracy in three ways: (1) computer-simulated current-spread and neural-health scenarios, (2) comparisons to psychophysical correlates of neural health and electrode-modiolus distances in human CI users, and (3) detection of simulated neural ‘dead’ regions (using forward masking) in human CI users. The PECAP algorithm reliably estimated the computer simulated scenarios. A moderate but significant negative correlation between focused thresholds and PECAP’s neural health estimates was found, consistent with previous literature. It also correctly identified simulated dead regions in seven CI users. The revised PECAP algorithm provides an estimate of the electrode-to-neuron interface in CIs that could be used to inform and optimize CI stimulation strategies for individual patients in clinical settings.

Electrophysiologic properties and ventricular fibrillation in normal and myopathic hearts

1999 ◽  
Vol 77 (7) ◽  
pp. 510-519 ◽  
Author(s):  
Katherine M Kavanagh ◽  
Patricia A Guerrero ◽  
Bodh I Jugdutt ◽  
Francis X Witkowski ◽  
Jeffrey E Saffitz
Keyword(s):  
Ventricular Fibrillation ◽  
Myocardial Dysfunction ◽  
Myocardial Cell ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Control Group ◽  
Functional Abnormality ◽  
Ventricular Ejection Fraction ◽  
Anisotropic Properties

This study tests the hypothesis that moderate myocardial dysfunction is associated with altered myocardial anisotropic properties and structurally altered ventricular fibrillation (VF). Mongrel dogs were randomized to either a control group or a group that was rapidly paced at 250 beats/min until the left ventricular ejection fraction was [Formula: see text] 40%. Changes in anisotropic properties and the electrical characteristics of VF associated with the development of moderate myocardial dysfunction were assessed by microminiature epicardial mapping studies. In vivo conduction, refractory periods, and repolarization times were prolonged in both longitudinal and transverse directions in myopathic animals versus controls. VF was different in myopathic versus control animals. There were significantly more conducted deflections during VF in normal hearts compared with myopathic hearts. Propagated deflection-to-deflection intervals during VF were significantly longer in myopathic hearts compared with controls (125.5 ± 49.06 versus 103.4 ± 32.9 ms, p = 0.009). There were no abnormalities in cell size, cell shape, or the number of intercellular gap junctions and there was no detectable change in the expression of the gap junction proteins Cx43 and Cx45. Moderate myocardial dysfunction is associated with significant electrophysiological abnormalities in the absence of changes in myocardial cell morphology or intercellular connections, suggesting a functional abnormality in cell-to-cell communication.Key words: cardiomyopathy, anisotropy, fibrillation, defibrillation.

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