Pacing-Induced Dyssynchrony During Early Reperfusion Reduces Infarct Size
Ward Y. Vanagt, MD*, ,*,
Richard N. Cornelussen, PhD*,
Tamara C. Baynham, PhD ,
Arne Van Hunnik*,
Quincy P. Poulina, MSc*,
Fawzi Babiker, PhD*,
Julio Spinelli, PhD,
Tammo Delhaas, MD, PhD*, and
Frits W. Prinzen, PhD*
* Physiology
Pediatrics, Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
Guidant Corporation, St. Paul, Minnesota.
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Figure 1 Study Protocol in Isolated Rabbit Hearts
Rabbit hearts were paced at the right atrium throughout the experiment. Dyssynchrony-induced preconditioning was induced by 3 cycles of 5-min left ventricular (LV) pacing, followed by 5 min of right atrial pacing. Dyssynchrony-induced postconditioning was induced by 10 cycles of 30-s LV pacing, interspersed with 30 s of right atrial pacing. LVPpostC = left ventricular pacing postconditioning; LVPpreC = left ventricular pacing preconditioning.
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Figure 2 Study Protocol in Anesthetized Pigs
Pig hearts were beating at sinus rhythm throughout the protocol. Dyssynchrony-induced post-conditioning was induced by 10 cycles of 30-s right ventricular (RV) pacing (atrial sense, ventricular pace), interspersed with 30 s of sinus rhythm. RVPpostC = right ventricular pacing postconditioning.
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Figure 3 Percent Infarction of LV Risk Area in Rabbit Hearts in the Control, LVPpreC, and LVPpostC Groups
Open symbols = individual data; solid symbols = group average ± SD. Abbreviations as in Figure 1.
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Figure 4 Blue Dye and TTC Staining in Representative Short-Axis Slices From Hearts in the Control and LVPpostC Groups
Note the uniform distribution of infarcted myocardium throughout the left ventricular (LV) area at risk. Dotted line = cross-sectional level of the presented slices; red line = level of coronary artery occlusion. LVPpostC = left ventricular pacing postconditioning; RV = right ventricle; TTC = triphenyltetrazolium chloride.
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Figure 5 Relative Change in Regional Stroke Work (Pressure-Length Loop Area) in the LV Wall
Depicted are values during left ventricular (LV) pacing before ischemia in the LV pacing preconditioning group and values during right atrial (RA) and LV pacing in early reperfusion (LV pacing postconditioning group). Dotted line represents baseline RA pacing. *p < 0.05 versus baseline RA pacing (t = 0) in same segment.
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Figure 6 Regional Perfusion of Rabbit Hearts (Fluorescent Microspheres) at 10 min Reperfusion
p = NS between and within groups. LVPpostC = left ventricular (LV) pacing postconditioning; Non-isch. = nonischemic myocardium; RA = right atrial; Reperf. = reperfused myocardium.
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Figure 7 Lactate Release (U/5 min/g) From Rabbit Hearts
*p < 0.05 versus baseline right atrial (RA) pacing within the same group. During LV pacing, lactate release was not significantly altered as compared with RA pacing at corresponding time points. Abbreviations as in Figure 1.
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Figure 8 Percent Infarction of LV Risk Area in Pig Hearts in the Control and RVPpostC Groups
Open symbols = individual data; solid symbols = group average ± SD. LV = left ventricular; RVPpostC = right ventricular pacing postconditioning.
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