scholarly journals Effects of lubeluzole on repolarization phase in canine heart assessed by endocardial monophasic action potential (MAP) recording

1995 ◽  
Vol 67 ◽  
pp. 127
Author(s):  
Atsushi Stigivama ◽  
Clieng Ni ◽  
Jiro Arita ◽  
Koji Eto ◽  
Keitaro Hashimoto
Keyword(s):  
Action Potential ◽  
Monophasic Action Potential ◽  
Canine Heart ◽  
Repolarization Phase ◽  
Potential Map

Mechanoelectrical feedback effects of altering preload, afterload, and ventricular shortening

1993 ◽  
Vol 264 (2) ◽  
pp. H423-H432 ◽  
Author(s):  
D. E. Hansen
Keyword(s):  
Stroke Volume ◽  
Action Potential ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Monophasic Action Potential ◽  
Canine Heart ◽  
Windkessel Model ◽  
Pump System ◽  
Ventricular Ejection Fraction ◽  
Ventricular Afterload

Electrophysiological consequences of altering ventricular load (mechanoelectrical feedback) were characterized in an isolated canine heart preparation. A computerized servo pump system controlled left ventricular volume and allowed ventricular ejection against a simulated arterial load (3-element Windkessel model). In 12 ventricles, end-diastolic volume (Ved) was held constant (end-diastolic pressure 6-12 mmHg) as arterial resistance (R) was varied (0.5-12 mmHg.s.ml-1), but afterload-dependent changes in the monophasic action potential (MAP) were not observed despite a large stroke volume effect. In contrast, when R was held constant in eight ventricles while Ved was increased from 20 to 40 ml, the plateau phase of the MAP was abbreviated, the terminal portion of phase 3 repolarization was delayed, and MAP duration measured at 20, 70, and 90% repolarization decreased (P < 0.05). In six ventricles, immediate transitions from isovolumic to ejecting mode at constant Ved did not alter MAP duration, but the magnitude of early afterdepolarizations (EADs), observed during isovolumic beats at high Ved, was reduced with resumption of ventricular ejection. As stroke volume of the initial ejecting contraction was increased by stepwise reductions of R, the magnitude of the EADs decreased progressively. Thus altering ventricular afterload does not modulate action potential duration in ventricles subjected to elevated, physiological, or even greatly reduced levels of afterload, whereas diastolic filling to high Ved does. Under conditions that lead to reduced stroke volume and high end-systolic volume, EADs are produced that are virtually abolished when ventricular ejection fraction is normalized.

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.

scholarly journals Monophasic action potential recordings: which is the recording electrode?

2016 ◽  
Vol 27 (5) ◽  
Author(s):  
Gary Tse ◽  
Sheung Ting Wong ◽  
Vivian Tse ◽  
Jie Ming Yeo
Keyword(s):  
Action Potential ◽  
Reference Electrode ◽  
Monophasic Action Potential ◽  
Current Debate ◽  
Recording Electrode ◽  
Close Proximity ◽  
Potential Map ◽  
Indifferent Electrode ◽  
Electrode Contact ◽  
Contact Electrode

AbstractThe aim of this article is to provide an overview of current debate on the monophasic action potential (MAP) recording technique, specifically whether the depolarizing or the reference electrode is responsible for recording the MAP waveform. A literature search was made using key words including monophasic action potential, MAP, electrophysiological basis, recording electrode, depolarizing electrode, contact electrode, indifferent electrode, and reference electrode. References from articles were screened for additional relevant papers. Articles published by the different experimental groups claim that depolarizing electrode, but not reference electrode, records MAPs from the myocardium. This can be more accurately described when considering biophysical theory, which states that MAP is a bipolar signal with contributions from not only the depolarizing electrode but also remote activation at the reference electrode. It is not meaningful to claim that one is the recording electrode because potential differences must be measured between two points in space. Nevertheless, the MAP technique is useful for assessing the local electrical activity of the myocardium in contact with the depolarizing electrode. It is important to have the recording electrode in close proximity with the reference electrode to minimize contamination from far-field signals.

scholarly journals Generation of Monophasic Action Potentials and Intermediate Forms

2020 ◽  
Author(s):  
Shahriar Iravanian ◽  
Ilija Uzelac ◽  
Conner Herndon ◽  
Jonathan J Langberg ◽  
Flavio H Fenton
Keyword(s):  
Action Potential ◽  
Cardiac Electrophysiology ◽  
Cardiac Tissue ◽  
Signal Generation ◽  
Monophasic Action Potential ◽  
Model Parameters ◽  
Pass Filter ◽  
Tissue Properties ◽  
Main Challenge ◽  
Potential Map

ABSTRACTThe Monophasic Action Potential (MAP) is a near replica of the transmembrane potential recorded when an electrode is pushed firmly against cardiac tissue. Despite its many practical uses, the mechanism of MAP signal generation and the reason it is so different from unipolar recordings is not completely known and is a matter of controversy. It is hypothesized that partial depolarization of the cells directly underneath the electrode contributes to the generation of MAP signals. In this paper, we describe a parametric, semi-quantitative method to generate realistic MAP and intermediate forms – multiphasic electrograms different from an ideal MAP – that does not require the partial depolarization hypothesis. The key ideas of our method are the formation of junctional spaces, i.e., electrically isolated pockets between the surface of an electrode and tissue, and the presence of a complex network of passive components that acts as a high-pass filter to distort the signal that reaches the recording amplifier. The passive network is formed by the interaction between the passive tissue properties and the double-layer capacitance of electrodes. We show that it is possible to generate different electrograms by the change of the model parameters and that both the MAP and intermediate forms reside on a continuum of signals. Our model helps to decipher the mechanisms of signal generation and can lead to a better design for electrodes, recording amplifiers, and experimental setups.SIGNIFICANCERecording the Monophasic Action Potential (MAP) is potentially very useful in both experimental and clinical cardiac electrophysiology and can provide valuable information about the repolarization phase of the action potential. However, despite its benefits, it currently has only a small and niche role. The main challenge is the technical difficulties of recording an ideal MAP. Our results provide a better understanding of the mechanisms of the generation of cardiac electrograms and may help to optimize experiments and improve tools to achieve the full potentials of recording the MAP signals.

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