Syncope during carotid sinus massage. Observations on conduction disturbances by atrial pacing, His-bundle and monophasic action potential (MAP) recordings

1973 ◽  
Vol 6 (3) ◽  
pp. 263-266 ◽  
Author(s):  
Leik Woie ◽  
Leif Brorson ◽  
S. Bertil Olsson
Keyword(s):  
Action Potential ◽  
Carotid Sinus ◽  
Monophasic Action Potential ◽  
Atrial Pacing ◽  
Carotid Sinus Massage ◽  
His Bundle ◽  
Conduction Disturbances ◽  
Potential Map

Regional electromechanical alternans in anesthetized pig hearts: modulation by mechanoelectric feedback

1994 ◽  
Vol 267 (5) ◽  
pp. H1726-H1735 ◽  
Author(s):  
C. F. Murphy ◽  
M. J. Lab ◽  
S. M. Horner ◽  
D. J. Dick ◽  
F. G. Harrison
Keyword(s):  
Left Ventricle ◽  
Action Potential ◽  
Monophasic Action Potential ◽  
Mechanical Activity ◽  
Strain Gauges ◽  
Atrial Pacing ◽  
Mechanoelectric Feedback ◽  
Pulsus Alternans ◽  
Electrical Alternans ◽  
Intact Heart

Electrical and mechanical alternans have often been found to coexist. However, the factors controlling their interdependence are not known. In this study we measure regional electrical and mechanical activity during mechanical alternans to investigate this relationship. Mechanical alternans was induced by rapid atrial pacing in 18 anesthetized, open-chest pigs. Regional segmental contraction and monophasic action potential were measured in three areas of left ventricle using epicardial tripodal strain gauges and suction electrodes. Electrical alternans always accompanied pulsus alternans. The phase of electrical alternans was not related to any measure of regional mechanical activity but did show a constant discordant relation to peak ventricular pressure. This suggested that mechanically dependent changes in action potential duration (mechanoelectric feedback) may be important in modulation electrical alternans. In support of this, pulsus alternans simulated by clamping the proximal aorta on alternate beats was associated with electrical alternans comparable to that produced with rapid atrial pacing. Mechanoelectric feedback modulates regional electrophysiology in the intact heart and may be important in the generation of electrical alternans.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document