Electromechanical Characterization of Chronic Myocardial Infarction in the Canine Coronary Occlusion Model

Abstract

Background-Defining the presence, extent, and nature of the dysfunctional myocardial tissue remains a cornerstone in diagnostic cardiology. A nonfluoroscopic, catheter-based mapping technique that can spatially associate endocardial mechanical and electrical data was used to quantify electromechanical changes in the canine chronic infarction model. Methods and Results-We mapped the left ventricular (LV) electromechanical regional properties in 11 dogs with chronic infarction (4 weeks after LAD ligation) and 6 controls. By sampling the location of a special catheter throughout the cardiac cycle at multiple endocardial sites and simultaneously recording local electrograms from the catheter tip, the dynamic 3-dimensional electromechanical map of the LV was reconstructed. Average endocardial local shortening (LS, measured at end systole and normalized to end diastole) and intracardiac bipolar electrogram amplitude were quantified at 13 LV regions. Endocardial LS was significantly lower at the infarcted area (1.2Ϯ0.9% [meanϮSEM], PϽ0.01) compared with the noninfarcted regions (7.2Ϯ1.1% to 13.5Ϯ1.5%) and with the same area in controls (15.5Ϯ1.2%, PϽ0.01). Average bipolar amplitude was also significantly lower at the infarcted zone (2.3Ϯ0.2 mV, PϽ0.01) compared with the same region in controls (10.3Ϯ1.3 mV) and with the noninfarcted regions (4.0Ϯ0.7 to 10.2Ϯ1.5 mV, PϽ0.01) in the infarcted group. In addition, the electrical maps could accurately delineate both the location and extent of the infarct, as demonstrated by the high correlation with pathology (Pearson's correlation coefficientϭ0.90) and by the precise identification of the infarct border. Conclusions-Chronic myocardial infarcted tissue can be characterized and quantified by abnormal regional mechanical and electrical functions. The unique ability to assess the regional ventricular electromechanical properties in various myocardial disease states may become a powerful tool in both clinical and research cardiology. (Circulation. 1998;98:2055-2064.)

Correlation of Scar in Cardiac MRI and High‐Resolution Contact Mapping of Left Ventricle in a Chronic Infarct Model

“…The tissue to electrogram comparison would also be limited by the presence of partial volume effect and other MRI artefacts as well as the relatively lower resolution of the MRI voxels (1 mm 3 ). The unipolar voltages recorded from scar tissue were higher than what is expected from experience in human scars, but similar to voltages recorded from canine scars12 and comparable to values from porcine ventricles 13. This may have been due to the smaller extent of transmural scar and perhaps due to exclusion of noncontact electrograms as the system automatically excluded electrograms from more than 2 mm from the endocardial surface.…”

“…Five mongrel dogs weighing 20–25 kg were used for the chronic infarct model 9, 12, 13. The protocol was approved by the Institutional Animal Care and Use Committee at Cedars‐Sinai Medical Center, Los Angeles, CA, USA.…”

“…The low‐voltage area and endocardial scar were defined on the bipolar voltage map as <2 mV and <1 mV, respectively. These values were chosen based on previous animal experiments demonstrating endocardial bipolar voltages in relation to myocardial scar 12, 13…”

Phase 1/2 Placebo-Controlled, Double-Blind, Dose-Escalating Trial of Myocardial Vascular Endothelial Growth Factor 2 Gene Transfer by Catheter Delivery in Patients With Chronic Myocardial Ischemia

“…12,29 Moreover, the identical LV anatomic site that was observed to be improved by EMM was consistently observed to be improved by SPECT Tc 99m sestamibi myocardial perfusion imaging as well. Initial experience with catheterbased GTx in the single-blind study referred to above confirmed these findings by demonstrating reproducibility of the SPECT and EMM maps from baseline to post-mock procedure, followed by site-specific improvement in both SPECT and EMM 90 days after the patient crossed over to VEGF2 GTx.…”

Electromagnetic Mapping During Complex RF Ablations

“…First it was presented in the NASPE meeting in 1996 (Smeets J et al, 1996;Ben-Haim SA et al, 1996a;Hayam G et al, 1996;Gepstein L et al, 1996), than published as a new method evaluated in animal model and human subjects (Ben-Haim SA et al, 1996b;Gepstein L et al, 1997, Shpun S et al, 1997Gepstein L et al, 1998). In this method, the locator pads, located beneath the operating table, generate a week magnetic field.…”