Increased ventricular repolarization heterogeneity in patients with ventricular arrhythmia vulnerability and cardiomyopathy: a human in vivo study

2006 ◽  
Vol 290 (1) ◽  
pp. H79-H86 ◽  
Author(s):  
Vijay S. Chauhan ◽  
Eugene Downar ◽  
Kumaraswamy Nanthakumar ◽  
John D. Parker ◽  
Heather J. Ross ◽  
...  
Keyword(s):  
Ventricular Arrhythmia ◽  
Ventricular Arrhythmias ◽  
Conduction Block ◽  
Left Ventricular ◽  
Ventricular Repolarization ◽  
Similar Patient ◽  
T Wave Alternans ◽  
Activation Times ◽  
Unipolar Electrograms

Increased repolarization heterogeneity can provide the substrate for reentrant ventricular arrhythmias in animal models of cardiomyopathy. We hypothesized that ventricular repolarization heterogeneity is also greater in patients with cardiomyopathy and ventricular arrhythmia vulnerability (inducible ventricular tachycardia or positive microvolt T wave alternans, VT/TWA) compared with a similar patient population without ventricular arrhythmia vulnerability (no VT/TWA). Endocardial and epicardial repolarization heterogeneity was measured in patients with ( n = 12) and without ( n = 10) VT/TWA by using transvenous 26-electrode catheters placed along the anteroseptal right ventricular endocardium and left ventricular epicardium. Local activation times (AT), activation-recovery intervals (ARI), and repolarization times (RT) were measured from unipolar electrograms. Endocardial RT dispersion along the apicobasal ventricle was greater ( P < 0.005) in patients with VT/TWA than in those without VT/TWA because of greater ARI dispersion ( P < 0.005). AT dispersion was similar between the two groups. Epicardial RT dispersion along the apicobasal ventricle was greater ( P < 0.05) in patients with VT/TWA than in those without VT/TWA because of greater ARI dispersion ( P < 0.05). AT dispersion was similar between the two groups. A plot of AT as a function of ARI revealed an inverse linear relationship for no VT/TWA such that progressively later activation was associated with progressively shorter ARI. The AT-ARI relationship was nonlinear in VT/TWA. In conclusion, patients with cardiomyopathy and VT/TWA have greater endocardial and epicardial repolarization heterogeneity than those without VT/TWA without associated conduction slowing. The steep repolarization gradients in VT/TWA may provide the substrate for functional conduction block and reentrant ventricular arrhythmias.

scholarly journals The Use of Electrocardiographic Imaging in Localising the Origin of Arrhythmias During Catheter Ablation of Ventricular Tachycardia

2021 ◽  
Vol 10 (3) ◽  
pp. 211-217
Author(s):  
Adam J Graham ◽  
Richard J Schilling
Keyword(s):  
Inverse Problem ◽  
Ventricular Arrhythmia ◽  
Clinical Tool ◽  
Electrocardiographic Imaging ◽  
Surface Electrodes ◽  
Non Invasive ◽  
Large Target ◽  
The Us ◽  
Activation Times ◽  
Unipolar Electrograms

Non-invasive electrocardiographic imaging (ECGI) is a novel clinical tool for mapping ventricular arrhythmia. Using multiple body surface electrodes to collect unipolar electrograms and conventional medical imaging of the heart, an epicardial shell can be created to display calculated electrograms. This calculation is achieved by solving the inverse problem and allows activation times to be calculated from a single beat. The technology was initially pioneered in the US using an experimental torso-shaped tank. Accuracy from studies in humans has varied. Early data was promising, with more recent work suggesting only moderate accuracy when reproducing cardiac activation. Despite these limitations, the system has been successfully used in pioneering work with non-invasive cardiac radioablation to treat ventricular arrhythmia. This suggests that the resolution may be sufficient for treatment of large target areas. Although untested in a well conducted clinical study it is likely that it would not be accurate enough to guide more discreet radiofrequency ablation.

Ventricular fibrillation in myopathic human hearts: mechanistic insights from in vivo global endocardial and epicardial mapping

2007 ◽  
Vol 292 (6) ◽  
pp. H2589-H2597 ◽  
Author(s):  
Stéphane Massé ◽  
Eugene Downar ◽  
Vijay Chauhan ◽  
Elias Sevaptsidis ◽  
Kumaraswamy Nanthakumar
Keyword(s):  
Ventricular Fibrillation ◽  
Electrical Activity ◽  
Conduction Block ◽  
Left Ventricular ◽  
Ventricular Cardiomyopathy ◽  
Epicardial Mapping ◽  
Border Regions ◽  
Number Of Cycles ◽  
The Hilbert Transform

Ventricular fibrillation (VF) is an important cause of sudden cardiac death and cardiovascular mortality in patients with cardiomyopathy. Although it was generally believed that chaotic reentrant wavefronts underlie VF in humans, there is emerging evidence of spatiotemporal organization during early VF. The mechanism of this organization of electrical activity in early VF is unknown in myopathic hearts. We studied early VF in vivo, intraoperatively in five cardiomyopathic patients. Simultaneous electrograms were obtained from the epicardium and endocardium in left ventricular cardiomyopathy and from the endocardium in right ventricular myopathy. The Hilbert transform was used to derive the phase of the electrograms. Rotors were identified by isolating phase singularity points. Rotors were present in all of the myopathic hearts studied during VF and cumulatively lasted a mean of 3.2 ± 2.0 s of the 7.0 ± 4.0 s of the VF segments analyzed. For each surface mapped, 3.6 ± 2.9 rotors were identified for the duration mapped. The average number of cycles completed by these rotors was 4.9 ± 4.9. The longest rotor lasted 10.2 ± 6.2 rotations and lasted 2.0 ± 1.2 s. The rotors on the endocardium had a cycle length of 192 ± 33 ms compared with 220 ± 15 ms on the epicardium ( P = 0.08). There is centrifugal activation of electrical activity from these rotors, and they give rise to domains that activate at faster rates with evidence of conduction block at the border with slower domains. These rotors frequently localized to border regions of myocardium with bipolar electrogram amplitude of <0.5 mV. The organization of electrical activity during early VF in myopathic human hearts is characterized by wavefronts emanating from a few rotors.

Mechanistic Insights Into Ventricular Arrhythmias Associated With Sickle Cell Disease: Role Of Abnormal Repolarization

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 980-980
Author(s):  
I D Greener ◽  
C A Rutledge ◽  
T Abassi ◽  
K Yadav ◽  
A B Desai ◽  
...  
Keyword(s):  
Sickle Cell Disease ◽  
Myocardial Fibrosis ◽  
Sickle Cell ◽  
Ventricular Arrhythmias ◽  
Normal Sinus Rhythm ◽  
Retrospective Chart Review ◽  
Left Ventricular ◽  
Cell Disease ◽  
Heart Rates

Abstract Introduction Sudden death, ventricular arrhythmias, prolonged QTc on ECG, and myocardial fibrosis have been documented independently in patients with sickle cell disease (SCD). We hypothesized that these electrical abnormalities are associated with myocardial fibrosis, ventricular arrhythmias, and death in SCD. Methods & Results A retrospective chart review of 195 SCD patients seen at the University of Illinois at Chicago was performed evaluating the association of ECG intervals with documented mortality and/or ventricular tachycardia (VT). Only ECGs demonstrating normal sinus rhythm and heart rates < 100 were included. Significant increases in PR (181 + 30 vs 162 + 26 ms, p=0.009), QRS (102 + 24 vs 89 + 11ms, p=0.0002), QTc (456 + 36 vs 441 + 25, p=0.02), and Tp-Te (duration between peak to end of T wave in lead V5, 114 + 46 vs 76 + 23, p=2.11X10-7) intervals were associated with a combined endpoint of all-cause mortality and VT (n=16 compared to n=179 SCD controls) with similar heart rates across both groups (78 + 14 vs. 77 + 11, p=0.72). To elucidate the mechanisms underlying this increased clinical risk in SCD patients, we investigated hearts from a mouse model of SCD. Cardiac electrical stimulation in vivo induced ventricular arrhythmias in 3/4 homozygous (-/-) SCD compared to only 1/5 wild-type (WT) hearts. Interestingly, Tp-Te– an established sudden cardiac death predictor- was significantly prolonged in -/- SCD vs. WT mice (5.6 + 0.29 vs. 4.1 + 0.37 msec ; p<0.05). Furthermore, left ventricular (LV) effective refractory periods (37+ 2.3 vs. 22 + 4.57 ms; p<0.05) and mid-anterior (LV) monophasic action potentials (MAPs) of -/- SCD mice, revealed increased duration compared to WT mice (53 + 2.3 vs. 33 + 6.9 ms; p<0.05). Conclusion In SCD patients, poor clinical outcomes are associated with abnormalities in depolarization and, prominently, repolarization. The SCD mouse exhibited arrhythmia vulnerability associated with repolarization abnormalities (Tp-Te, LV MAPs). The SCD mouse may represent a useful model for deciphering the mechanisms underlying the apparent increased arrhythmia burden in SCD patients. Disclosures: Hillery: Bayer: Consultancy; Biogen Idec: Consultancy.

Electrocardiographic landmarks of idiopathic ventricular arrhythmia origins

Heart ◽  
2019 ◽  
Vol 105 (14) ◽  
pp. 1109-1116 ◽  
Author(s):  
Stylianos Tzeis ◽  
Dimitrios Asvestas ◽  
Siew Yen Ho ◽  
Panos Vardas
Keyword(s):  
Heart Disease ◽  
Ventricular Arrhythmia ◽  
Ventricular Arrhythmias ◽  
Structural Heart Disease ◽  
Left Ventricular ◽  
Outflow Tract ◽  
Myocardial Scar ◽  
Mapping Tool ◽  
Surface Ecg

Idiopathic ventricular arrhythmias occur in the absence of underlying structural heart disease and less commonly in the presence of coexistent, but mechanistically unrelated, myocardial scar. These arrhythmias originate from several anatomical sites in both ventricles, with a predilection in outflow tract structures. The 12-lead surface ECG is the initial mapping tool, which is widely used to identify their origin. Specific features can predict the site of idiopathic ventricular arrhythmias, thus differentiating right from left ventricular, as well as endocardial from epicardial origins. In this review, we aim to analyse electrocardiographic landmarks for determination of idiopathic ventricular arrhythmia sources, with specific emphasis on pertinent caveats and anatomical relationships.

scholarly journals Microvolt T-wave Alternans: Where Are We Now?

2016 ◽  
Vol 5 (1) ◽  
pp. 37 ◽  
Author(s):  
Aapo L Aro ◽  
◽  
Tuomas V Kenttä ◽  
Heikki V Huikuri ◽  
◽  
...  
Keyword(s):  
Average Method ◽  
Ventricular Arrhythmias ◽  
Moving Average ◽  
Cardiovascular Death ◽  
Left Ventricular ◽  
Sufficient Evidence ◽  
T Wave ◽  
T Wave Alternans ◽  
The Time Domain ◽  
Important Marker

Microvolt T-wave alternans (TWA), characterised as beat-to-beat fluctuation of T-wave amplitude and morphology, is an electrophysiological phenomenon associated clinically with impending ventricular arrhythmias and is an important marker of arrhythmia risk. Currently, two main methods for the detection of TWA exist, namely, the spectral method and the time-domain modified moving average method; both are discussed in this review. Microvolt TWA has been associated with cardiovascular mortality and sudden cardiac death in several clinical studies involving >14,000 subjects with reduced as well as preserved left ventricular function. Although TWA appears to be a useful marker of susceptibility for lethal ventricular arrhythmias and cardiovascular death, so far there is no sufficient evidence from randomised clinical trials to support its use in guiding therapy. However, several ongoing trials are expected to provide more information about the clinical use of TWA testing.

Opposite effects of lidocaine and diltiazem on electrophysiologic alterations in acutely ischemic porcine myocardium

1989 ◽  
Vol 67 (7) ◽  
pp. 697-703 ◽  
Author(s):  
René Cardinal ◽  
D. Leigh Carson ◽  
Chantal Lambert ◽  
Jafar Shenasa ◽  
Robert Parent ◽  
...  
Keyword(s):  
Ventricular Arrhythmias ◽  
St Segment ◽  
St Elevation ◽  
The Difference ◽  
Activation Times ◽  
Electrical Alternans ◽  
Transmembrane Currents ◽  
Ischemic Arrhythmias ◽  
Unipolar Electrograms ◽  
T Waves

To investigate the actions of lidocaine and diltiazem on the ischemic alterations associated with the onset of acute ischemic arrhythmias, the left anterior descending coronary artery was occluded for 6-min periods separated by 30 min of reperfusion, under control conditions and after injection of lidocaine (2.4–3.8 μg/mL of plasma) or diltiazem (390–510 ng/mL) in open–chest anesthetized pigs. Sixty-one unipolar electrograms were continuously recorded in the ischemic zone. Isochronal maps and isopotential maps were determined by computer analysis. The magnitude of beat-to-beat alternation of unipolar waveforms was described by the difference between the time integrals subtended by electrograms of consecutive beats. Activation times were prolonged by ischemia and the ST segment became elevated. Delay and ST elevation developed at a faster rate in the presence of lidocaine than under control conditions, but were reduced by diltiazem. ST-T alternation was not significantly different between control and lidocaine occlusions, but the incidence of negative T waves and that of ventricular tachycardia degenerating to fibrillation were higher in lidocaine occlusions than in control occlusions. In contrast, unipolar waveform alternation and negative T waves were virtually abolished by diltiazem, even at fast pacing rates (180–210 beats/min) at which diltiazem did not reduce ST elevation. Ventricular arrhythmias also were abolished by diltiazem. Thus, lidocaine and diltiazem produce opposite effects on the ischemic alterations most closely associated with the initiating mechanism of tachycardia. This could be related to differences between these drugs with regard to their actions on transmembrane currents during repolarization.Key words: acute myocardial ischemia, lidocaine, diltiazem, ventricular arrhythmias, electrical alternans.

scholarly journals Microvolt T-Wave Alternans and the Risk of Death or Sustained Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction

2006 ◽  
Vol 47 (2) ◽  
pp. 456-463 ◽  
Author(s):  
Daniel M. Bloomfield ◽  
J. Thomas Bigger ◽  
Richard C. Steinman ◽  
Pearila B. Namerow ◽  
Michael K. Parides ◽  
...  
Keyword(s):  
Left Ventricular Dysfunction ◽  
Ventricular Arrhythmias ◽  
Ventricular Dysfunction ◽  
Left Ventricular ◽  
Risk Of Death ◽  
T Wave ◽  
T Wave Alternans
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