Recognition of Fibrotic Infarct Density by the Pattern of Local Systolic-Diastolic Myocardial Electrical Impedance
Amorós-Figueras, Gerard (Institut d'Investigació Biomèdica Sant Pau)
Jorge, Esther (Institut d'Investigació Biomèdica Sant Pau)
García Sánchez, Tomás (Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica)
Bragos, Ramon (Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica)
Rosell Ferrer, Javier (Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica)
Cinca, Juan (Institut d'Investigació Biomèdica Sant Pau)
Universitat Autònoma de Barcelona

Fecha:	2016
Resumen:	Myocardial electrical impedance is a biophysical property of the heart that is influenced by the intrinsic structural characteristics of the tissue. Therefore, the structural derangements elicited in a chronic myocardial infarction should cause specific changes in the local systolic-diastolic myocardial impedance, but this is not known. This study aimed to characterize the local changes of systolic-diastolic myocardial impedance in a healed myocardial infarction model. Six pigs were successfully submitted to 150 min of left anterior descending (LAD) coronary artery occlusion followed by reperfusion. 4 weeks later, myocardial impedance spectroscopy (1-1000 kHz) was measured at different infarction sites. The electrocardiogram, left ventricular (LV) pressure, LV dP/dt, and aortic blood flow (ABF) were also recorded. A total of 59 LV tissue samples were obtained and histopathological studies were performed to quantify the percentage of fibrosis. Samples were categorized as normal myocardium (<10% fibrosis), heterogeneous scar (10-50%) and dense scar (>50%). Resistivity of normal myocardium depicted phasic changes during the cardiac cycle and its amplitude markedly decreased in dense scar (18 ± 2 Ω·cm vs. 10 ± 1 Ω·cm, at 41 kHz; P < 0. 001, respectively). The mean phasic resistivity decreased progressively from normal to heterogeneous and dense scar regions (285 ± 10 Ω·cm, 225 ± 25 Ω·cm, and 162 ± 6 Ω·cm, at 41 kHz; P < 0. 001 respectively). Moreover, myocardial resistivity and phase angle correlated significantly with the degree of local fibrosis (resistivity: r = 0. 86 at 1 kHz, P < 0. 001; phase angle: r = 0. 84 at 41 kHz, P < 0. 001). Myocardial infarcted regions with greater fibrotic content show lower mean impedance values and more depressed systolic-diastolic dynamic impedance changes. In conclusion, this study reveals that differences in the degree of myocardial fibrosis can be detected in vivo by local measurement of phasic systolic-diastolic bioimpedance spectrum. Once this new bioimpedance method could be used via a catheter-based device, it would be of potential clinical applicability for the recognition of fibrotic tissue to guide the ablation of atrial or ventricular arrhythmias.
Ayudas:	Instituto de Salud Carlos III FIS-PI13-00765 Instituto de Salud Carlos III DTS-15-00099 Instituto de Salud Carlos III RIC-RD12-0042-0002]
Nota:	Altres ajuts: Fundació "La Marató" de TV3 [20150830]
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	Healed myocardial infarction ; Myocardial electrical impedance ; Hemodynamics ; Novel bioimpedance device ; Swine
Publicado en:	Frontiers in physiology, Vol. 7 (august 2016) , ISSN 1664-042X

DOI: 10.3389/fphys.2016.00389
PMID: 27630580

10 p, 2.2 MB

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