Multisite dual surface monophasic action potential mapping in vivo: further evidence of three dimensional characteristics of atrial repolarization

2002 ◽  
Author(s):  
S. Shkurovich ◽  
A.V. Sahakian ◽  
T.V. Votapka ◽  
T. Ji ◽  
S. Swiryn
Keyword(s):  
Action Potential ◽  
Three Dimensional ◽  
Monophasic Action Potential ◽  
Potential Mapping ◽  
Atrial Repolarization

scholarly journals A protocol combining current- and voltage-clamp provides a novel and useful three-dimensional representation of cardiac action potential

2014 ◽  
Vol 87 (1) ◽  
Author(s):  
Massimiliano Zaniboni ◽  
Francesca Cacciani
Keyword(s):  
Action Potential ◽  
Current Source ◽  
Three Dimensional ◽  
Membrane Conductance ◽  
Ventricular Repolarization ◽  
Cardiac Action Potential ◽  
Dimensional Representation ◽  
Cardiac Action ◽  
Three Dimensional Representation

A compact three-dimensional representation of cardiac action potential (AP) properties in terms of current source is presented here. The experimental protocol used to obtain such representation is based on the measure of instantaneous current-voltage relationships during the course of the AP. The procedure, which combines current- and voltage-clamps on patch clamped cardiac myocytes, has been previously applied to real cells, and then extended to computer simulations with cellular ventricular AP models. The three-dimensional AP representation allows to easily estimate membrane resistance during repolarization, a key factor for the modulation of ventricular repolarization. It also shows that, during late ventricular repolarization, membrane conductance becomes negative, <em>i.e.</em> repolarization is auto-regenerative. The novel AP representation is therefore a useful tool for both in vivo and in silico cardiac cellular electrophysiological investigations.

Reflex vagal control of atrial repolarization

1996 ◽  
Vol 271 (3) ◽  
pp. H870-H875
Author(s):  
D. E. Euler ◽  
B. Olshansky ◽  
S. Y. Kim
Keyword(s):  
Action Potential ◽  
Sinus Bradycardia ◽  
Aortic Pressure ◽  
Aortic Occlusion ◽  
Monophasic Action Potential ◽  
Atrial Pacing ◽  
Sinus Arrhythmia ◽  
Vagal Control ◽  
The Right ◽  
Atrial Repolarization

The reflex vagal control of atrial repolarization was investigated in eight open-chest, anesthetized dogs. A monophasic action potential was recorded from the right atrium, and the action potential duration to 90% repolarization (APD90) was determined every cardiac cycle. beta-Adrenergic receptors were blocked with timolol (0.1 mg/kg). Under baseline conditions, sinus slowing during sinus arrhythmia was accompanied by a significant shortening of APD90 (24 +/- 4.0 ms). Transient occlusion (30 s) of the descending thoracic aorta increased systolic aortic pressure from 138 +/- 2.8 to 181 +/- 3.3 mmHg (P < 0.01). Heart rate decreased from 99 +/- 3.6 to 42.5 +/- 3.4 beats/min (P < 0.01), and APD90 shortened from 168 +/- 5.1 to 94 +/- 3.3 ms (P < 0.01). Release of the occlusion caused arterial hypotension (95 +/- 2.8 mmHg) and an overshoot in both rate (126 +/- 5.2 beats/min) and APD90 (189 +/- 2.3 ms). Aortic occlusion during atrial pacing (130-160 beats/min) decreased APD90 from 147 +/- 7.0 to 78 +/- 3.4 ms (P < 0.01). Cervical vagotomy or atropine eliminated changes in rate and APD90 evoked by aortic occlusion. The results indicate that there is parallel central vagal control of both sinus rate and atrial repolarization. Sinus bradycardia during reflex vagal activation does not prevent the acceleration of atrial repolarization.

A simultaneous multichannel monophasic action potential electrode array for in vivo epicardial repolarization mapping

2001 ◽  
Vol 48 (3) ◽  
pp. 345-353 ◽  
Author(s):  
A.V. Sahakian ◽  
M.-S.L. Peterson ◽  
S. Shkurovich ◽  
M. Hamer ◽  
T. Votapka ◽  
...  
Keyword(s):  
Action Potential ◽  
Electrode Array ◽  
Monophasic Action Potential ◽  
Potential Electrode

Rate-dependent differences in dog epi- and endocardial monophasic action potential configuration in vivo

1991 ◽  
Vol 261 (5) ◽  
pp. H1387-H1391 ◽  
Author(s):  
P. M. Tande ◽  
E. Mortensen ◽  
H. Refsum
Keyword(s):  
Action Potential ◽  
Phase 1 ◽  
Outward Current ◽  
Ventricular Repolarization ◽  
Monophasic Action Potential ◽  
Transient Outward Current ◽  
Phase 2 ◽  
Lower Phase

A transient outward current (Ito), long considered to be a unique feature of Purkinje fiber tissue, has recently been demonstrated in dog ventricular tissue in vitro and most prominently in the epicardium. To investigate its possible contribution to ventricular repolarization in vivo, we recorded right ventricular endocardial and epicardial monophasic action potentials (MAP) simultaneously in pentobarbital-anesthetized open-chest dogs. Epicardial MAP had lower phase 1 than phase 2 amplitude at both spontaneous heart rate and paced cycle length of 300 and 400 ms. This "spike-and-dome" morphology of the epicardial MAP, possibly attributable to Ito, progressively disappeared at shorter extrastimulus intervals. In endocardium the phase 1 amplitude was always higher or equal to phase 2 amplitude and was not affected by shorter extrastimulus intervals. The action potential duration (APD) was shorter in epicardium than in endocardium. Both endocardial and epicardial APD shortened as the premature intervals were reduced, but the shortening was not parallel. The restitution curves converged so that, at the shortest intervals (160 ms), there were no longer any significant differences in APD between endocardium and epicardium. This study indicates that Ito contributes to ventricular repolarization in vivo, and most prominently in the epicardium. Unequal shortening of APD between endocardium and epicardium after progressively shorter diastolic intervals may thus partly result from uneven distribution of Ito across the ventricular wall.

Genesis of the monophasic action potential: role of interstitial resistance and boundary gradients

2004 ◽  
Vol 286 (4) ◽  
pp. H1370-H1381 ◽  
Author(s):  
Joseph V. Tranquillo ◽  
Michael R. Franz ◽  
Björn C. Knollmann ◽  
Alexandra P. Henriquez ◽  
Doris A. Taylor ◽  
...  
Keyword(s):  
Action Potential ◽  
Time Course ◽  
Cardiac Tissue ◽  
Mechanical Load ◽  
Critical Role ◽  
Applied Pressure ◽  
Three Dimensional ◽  
Membrane Dynamics ◽  
Monophasic Action Potential ◽  
Tissue Properties

The extracellular potential at the site of a mechanical deformation has been shown to resemble the underlying transmembrane action potential, providing a minimally invasive way to access membrane dynamics. The biophysical factors underlying the genesis of this signal, however, are still poorly understood. With the use of data from a recent experimental study in a murine heart, a three-dimensional anisotropic bidomain model of the mouse ventricular free wall was developed to study the currents and potentials resulting from the application of a point mechanical load on cardiac tissue. The applied pressure is assumed to open nonspecific pressure-sensitive channels depolarizing the membrane, leading to monophasic currents at the electrode edge that give rise to the monophasic action potential (MAP). The results show that the magnitude and the time course of the MAP are reproduced only for certain combinations of local or global intracellular and interstitial resistances that form a resting tissue length constant that, if applied over the entire domain, is smaller than that required to match the wave speed. The results suggest that the application of pressure not only causes local depolarization but also changes local tissue properties, both of which appear to play a critical role in the genesis of the MAP.

scholarly journals New insights into application of cardiac monophasic action potential

2010 ◽  
pp. 645-650
Author(s):  
S-G Yang ◽  
O Kittnar
Keyword(s):  
Action Potential ◽  
Time Course ◽  
Cardiac Tissue ◽  
Femoral Vein ◽  
Myocardial Cell ◽  
Monophasic Action Potential ◽  
Seldinger Technique ◽  
Accurate Information ◽  
Length Changes

Monophasic action potential (MAP) recording plays an important role in a more direct view of human myocardial electrophysiology under both physiological and pathological conditions. The procedure of MAP measuring can be simply performed using the Seldinger technique, when MAP catheter is inserted through femoral vein into the right ventricle or through femoral artery to the left ventricle. The MAP method represents a very useful tool for electrophysiological research in cardiology. Its crucial importance is based upon the fact that it enables the study of the action potential (AP) of myocardial cell in vivo and, therefore, the study of the dynamic relation of this potential with all the organism variables. This can be particularly helpful in the case of arrhythmias. There are no doubts that physiological MAP recording accuracy is almost the same as transmembrane AP as was recently confirmed by anisotropic bidomain model of the cardiac tissue. MAP recording devices provide precise information not only on the local activation time but also on the entire local repolarization time course. Although the MAP does not reflect the absolute amplitude or upstroke velocity of transmembrane APs, it delivers highly accurate information on AP duration and configuration, including early afterdepolarizations as well as relative changes in transmembrane diastolic and systolic potential changes. Based on available data, the MAP probably reflects the transmembrane voltage of cells within a few millimeters of the exploring electrode. Thus MAP recordings offer the opportunity to study a variety of electrophysiological phenomena in the in situ heart (including effects of cycle length changes and antiarrhythmic drugs on AP duration).

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