scholarly journals Evolution of Action Potential Alternans in Rabbit Heart during Acute Regional Ischemia

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Irma Martišienė ◽  
Jonas Jurevičius ◽  
Rūta Vosyliūtė ◽  
Antanas Navalinskas ◽  
Rimantas Treinys ◽  
...  
Keyword(s):  
Action Potential ◽  
Phase I ◽  
Rabbit Heart ◽  
Spatiotemporal Pattern ◽  
Gradual Decline ◽  
Microelectrode Recordings ◽  
Regional Ischemia ◽  
Ischemic Region ◽  
Acute Regional Ischemia ◽  
Over Time

This study investigates the development of the spatiotemporal pattern of action potential alternans during acute regional ischemia. Experiments were carried out in isolated Langendorff-perfused rabbit heart using a combination of optical mapping and microelectrode recordings. The alternans pattern significantly changed over time and had a biphasic character reaching maximum at 6–9 min after occlusion. Phase I (3–11 minutes of ischemia) is characterized by rapid increase in the alternans magnitude and expansion of the alternans territory. Phase I is followed by gradual decline of alternans (Phase II) in both magnitude and territory. During both phases we observed significant beat-to-beat variations of the optical action potential amplitude (OAPA) alternans. Simultaneous microelectrode recordings from subepicardial and subendocardial layers showed that OAPA alternans coincided with intramural 2 : 1 conduction blocks. Our findings are consistent with the modeling studies predicting that during acute regional ischemia alternans can be driven by 2 : 1 conduction blocks in the ischemic region.

scholarly journals Alternans in Rabbit Heart During Acute Regional Ischemia: Optical Mapping and Microelectrode Recordings

2014 ◽  
Vol 106 (2) ◽  
pp. 122a
Author(s):  
Irma Martišienė ◽  
Jonas Jurevičius ◽  
Ruta Vosyliutė ◽  
Antanas Navalinskas ◽  
Rimantas Treinys ◽  
...  
Keyword(s):  
Optical Mapping ◽  
Rabbit Heart ◽  
Microelectrode Recordings ◽  
Regional Ischemia ◽  
Acute Regional Ischemia

EVOLUTION OF ACTION POTENTIAL ALTERNANS IN RABBIT HEART DURING ACUTE REGIONAL ISCHEMIA

Heart Rhythm ◽  
2014 ◽  
Vol 11 (11) ◽  
pp. 2136
Author(s):  
A. Matiukas ◽  
I. Martisiene ◽  
J. Jurevicius ◽  
R. Vosyliute ◽  
A. Navalinskas ◽  
...  
Keyword(s):  
Action Potential ◽  
Rabbit Heart ◽  
Regional Ischemia ◽  
Acute Regional Ischemia

Mechanism of atrioventricular nodal facilitation in the rabbit heart: role of the distal AV node

1997 ◽  
Vol 272 (6) ◽  
pp. H2815-H2825 ◽  
Author(s):  
G. J. Fahy ◽  
I. Efimov ◽  
Y. Cheng ◽  
G. A. Kidwell ◽  
D. Van Wagoner ◽  
...  
Keyword(s):  
Action Potential ◽  
Action Potential Duration ◽  
Cellular Response ◽  
Rabbit Heart ◽  
Av Node ◽  
Microelectrode Recordings ◽  
Bundle Of His ◽  
Action Potential Shortening

We investigated whether atrioventricular (AV) nodal facilitation is the result of distal AV nodal action potential shortening. Atrial and bundle of His (H) electrograms and microelectrode recordings from proximal and distal AV nodal cells were analyzed in eight superfused rabbit AV node preparations in response to two pacing protocols. In the facilitation protocol, an atrial extrastimulus (A3) was preceded by an atrial impulse (A2) introduced 300, 200, 150, or 125 ms after 30 basic beats (A1). The preexcitation protocol differed from the facilitation protocol by the addition of a premature His depolarization (h2) such that the H1-h2 interval was shorter than the H1-H2 interval. Conduction curves (A3-H3 vs. H2-A3, h2-A3, and A2-A3 intervals) were constructed. Facilitation was demonstrated in all preparations when H2-A3 was used (P = 0.02) but not in the A2-A3 format. Compared with facilitation at the same A1-A2 intervals, preexcitation, despite shortening the distal cellular action potential duration, resulted in longer A3-H3 delays (P = 0.002), shorter A2-A3 intervals, and depression of the proximal nodal cellular response. Thus facilitation does not result from altered distal AV nodal characteristics and instead is a manifestation of an uncontrolled pacing protocol-dependent modulation of proximal AV nodal function.

scholarly journals Studies on prolonged acute regional ischemia

1989 ◽  
Vol 98 (4) ◽  
pp. 557-566 ◽  
Author(s):  
Friedhelm Beyersdorf ◽  
Christophe Acar ◽  
Gerald D. Buckberg ◽  
Marshall T. Partington ◽  
Fumiyuki Okamoto ◽  
...  
Keyword(s):  
Regional Ischemia ◽  
Acute Regional Ischemia

High-resolution1H NMR imaging of regional ischemia in the isolated perfused rabbit heart at 4.7 T

1991 ◽  
Vol 21 (1) ◽  
pp. 144-150 ◽  
Author(s):  
John C. Chatham ◽  
Stacey Ackerman ◽  
Stephen J. Blackband
Keyword(s):  
Rabbit Heart ◽  
Nmr Imaging ◽  
Regional Ischemia ◽  
Perfused Rabbit Heart

Rate-dependent shortening of action potential duration increases ventricular vulnerability in failing rabbit heart

2011 ◽  
Vol 300 (2) ◽  
pp. H565-H573 ◽  
Author(s):  
Masahide Harada ◽  
Yukiomi Tsuji ◽  
Yuko S. Ishiguro ◽  
Hiroki Takanari ◽  
Yusuke Okuno ◽  
...  
Keyword(s):  
Action Potential ◽  
High Frequency ◽  
Rabbit Heart ◽  
Left Ventricular ◽  
High Frequency Stimulation ◽  
Electrophysiological Properties ◽  
Rate Dependent ◽  
Frequency Stimulation ◽  
And Control

Congestive heart failure (CHF) predisposes to ventricular fibrillation (VF) in association with electrical remodeling of the ventricle. However, much remains unknown about the rate-dependent electrophysiological properties in a failing heart. Action potential properties in the left ventricular subepicardial muscles during dynamic pacing were examined with optical mapping in pacing-induced CHF ( n = 18) and control ( n = 17) rabbit hearts perfused in vitro. Action potential durations (APDs) in CHF were significantly longer than those observed for controls at basic cycle lengths (BCLs) >1,000 ms but significantly shorter at BCLs <400 ms. Spatial APD dispersions were significantly increased in CHF versus control (by 17–81%), and conduction velocity was significantly decreased in CHF (by 6–20%). In both groups, high-frequency stimulation (BCLs <150 ms) always caused spatial APD alternans; spatially concordant alternans and spatially discordant alternans (SDA) were induced at 60% and 40% in control, respectively, whereas 18% and 82% in CHF. SDA in CHF caused wavebreaks followed by reentrant excitations, giving rise to VF. Incidence of ventricular tachycardia/VFs elicited by high-frequency dynamic pacing (BCLs <150 ms) was significantly higher in CHF versus control (93% vs. 20%). In CHF, left ventricular subepicardial muscles show significant APD shortenings at short BCLs favoring reentry formations following wavebreaks in association with SDA. High-frequency excitation itself may increase the vulnerability to VF in CHF.

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