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).

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 Experimental Evaluation of the Cardiac Rhythm Originating in Myocardial Sleeves of Pulmonary Veins Using a Monophasic Action Potential

2013 ◽  
pp. S49-S56
Author(s):  
O. KITTNAR ◽  
S.-G. YANG ◽  
M. MLČEK
Keyword(s):  
Action Potential ◽  
Sinus Node ◽  
Pulmonary Veins ◽  
Myocardial Cell ◽  
Monophasic Action Potential ◽  
Similar Action ◽  
Potential Map ◽  
Vagal Nerves ◽  
Treatment Procedures

Spontaneous depolarization similar to that from the sinus node was documented from the myocardial sleeves of pulmonary veins (PV) after isolation procedures. It was then hypothesized that sinus node-like tissue is present in the PVs of humans. Based on a number of features, the myocardium of myocardial sleeves (MS) is highly arrhythmogenic. Membrane potentials originating from MS are invariably recordable at the PVs ostia in patients with atrial fibrillation (AF) and delayed conduction around the PVs ostia may play a role in re-entry process responsible for the initiation and maintenance of AF. Diagnostic and therapeutic evidence of premature atrial beats induced in MS of PVs and resulting in launch of AF was detected by 3D electroanatomic method of monophasic action potential (MAP). MAP recording plays an important role in a direct view of human myocardial electrophysiology under both physiological and pathological conditions. Its crucial importance lies in the fact that it enables the study of the action potential of myocardial cell in vivo and, therefore, the study of the dynamic relation of this potential with all the organism variables. The knowledge of pathological MAPs from PV myocardial sleeves can help us to confirm a diagnosis when finding the similar action potential morphology. MAP can be also used to evaluate the therapeutic efficiency of vagal nerves suppression, radiofrequency ablation or other treatment procedures in PVs myocardial sleeves as well as for post-treatment following up.

scholarly journals Optimisation of a Generic Ionic Model of Cardiac Myocyte Electrical Activity

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Tianruo Guo ◽  
Amr Al Abed ◽  
Nigel H. Lovell ◽  
Socrates Dokos
Keyword(s):  
Action Potential ◽  
Time Course ◽  
Cardiac Myocyte ◽  
Cardiac Tissue ◽  
Ionic Currents ◽  
Experimental Information ◽  
Electrical Stimulus ◽  
Right Atrial ◽  
Ionic Model ◽  
Multiple Datasets

A generic cardiomyocyte ionic model, whose complexity lies between a simple phenomenological formulation and a biophysically detailed ionic membrane current description, is presented. The model provides a user-defined number of ionic currents, employing two-gate Hodgkin-Huxley type kinetics. Its generic nature allows accurate reconstruction of action potential waveforms recorded experimentally from a range of cardiac myocytes. Using a multiobjective optimisation approach, the generic ionic model was optimised to accurately reproduce multiple action potential waveforms recorded from central and peripheral sinoatrial nodes and right atrial and left atrial myocytes from rabbit cardiac tissue preparations, under different electrical stimulus protocols and pharmacological conditions. When fitted simultaneously to multiple datasets, the time course of several physiologically realistic ionic currents could be reconstructed. Model behaviours tend to be well identified when extra experimental information is incorporated into the optimisation.

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

scholarly journals Transmural recording of monophasic action potentials

2002 ◽  
Vol 282 (3) ◽  
pp. H855-H861 ◽  
Author(s):  
Xiaohong Zhou ◽  
Jian Huang ◽  
Raymond E. Ideker
Keyword(s):  
Guinea Pig ◽  
Action Potential ◽  
Refractory Period ◽  
Time Course ◽  
Monophasic Action Potential ◽  
Papillary Muscles ◽  
Transmembrane Potentials ◽  
Potential Map ◽  
Monophasic Action Potentials ◽  
Injury Potential

To investigate the possibility of transmural recording of repolarization through the ventricular wall, KCl monophasic action potential (MAP) electrodes positioned along plunge needles were developed and tested. The MAP electrode consists of a silver wire surrounded by agarose gel containing KCl, which slowly eluted into the adjacent tissue to depolarize it. In six dogs, a plunge needle containing three KCl MAP electrodes was inserted into the left ventricle to simultaneously record from the subepicardium, midwall, and subendocardium. In six pigs, eight plunge needles containing three KCl MAP electrodes and two plunge needles containing similar electrodes except for the absence of KCl were inserted into the ventricles. In three guinea pig papillary muscles, a KCl electrode was used to record MAPs along with two microelectrodes for recording transmembrane potentials. Transmural MAP recordings could be made for >1 h in dogs and >2 h in pigs with a significant decrease in MAP amplitude over time but without a significant change in MAP duration. With the electrodes without KCl in pigs, the injury potentials subsided in <30 min. When the pacing rate was changed to alter the action potential duration and refractory period in dogs, the MAP duration correlated with the local effective refractory period ( r = 0.94). The time course of the MAP duration recorded with a KCl MAP electrode in guinea pig papillary muscles corresponded well with that of the transmembrane potential recorded with an adjacent microelectrode. It is possible to record transmural repolarization of the ventricles with KCl MAP electrodes on plunge needles. The MAP is caused by the KCl rather than being a nonspecific injury potential.

IN VIVO MUSCLE LENGTH CHANGES IN BUMBLEBEES AND THE IN VITRO EFFECTS ON WORK AND POWER

1993 ◽  
Vol 183 (1) ◽  
pp. 101-113 ◽  
Author(s):  
K. M. Gilmour ◽  
C. P. Ellington
Keyword(s):  
High Speed ◽  
Time Course ◽  
Second Harmonic ◽  
Muscle Length ◽  
Muscle Fibres ◽  
Bombus Lucorum ◽  
Length Changes ◽  
In Vitro Effects

The amplitude and time course of muscle length changes were examined in vivo in tethered, flying bumblebees Bombus lucorum. A ‘window’ was cut in the dorsal cuticle and aluminium particles were placed on the exposed dorsal longitudinal muscle fibres. Muscle oscillations were recorded using high-speed video and a high-magnification lens. The amplitude of muscle length changes was 1.9 % (s.d.=0.5 %, N=7), corresponding to the commonly quoted strain of 1–3 % for asynchronous muscle. Higher harmonics, particularly the second, were found in the muscle oscillations and in the wing movements. The second harmonic for wing movements was damped in comparison to that for muscle length changes, probably as a result of compliance in the thoracic linkage. Inclusion of the second harmonic in the driving signal for in vitro experiments on glycerinated fibres generally resulted in a decrease in the work and power, but a substantial increase was found for some fibres.

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.

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