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Título:	Early detection of acute transmural myocardial ischemia by the phasic systolic-diastolic changes of local tissue electrical impedance
Autor/a:	Jorge, Esther; Amoros Figueras, Gerard; García Sánchez, Tomás; Bragós Bardia, Ramon; Rosell Ferrer, Francisco Javier; Cinca Cuscullola, Juan Maria
Otros autores:	Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica; Universitat Politècnica de Catalunya. IEB - Instrumentació Electrònica i Biomèdica
Abstract:	Myocardial electrical impedance is influenced by the mechanical activity of the heart. Therefore, the ischemia-induced mechanical dysfunction may cause specific changes in the systolic-diastolic pattern of myocardial impedance, but this is not known. This study aimed to analyze the phasic changes of myocardial resistivity in normal and ischemic conditions. Myocardial resistivity was measured continuously during the cardiac cycle using 26 different simultaneous excitation frequencies (1 kHz–1 MHz) in 7 anesthetized open-chest pigs. Animals were submitted to 30 min regional ischemia by acute left anterior descending coronary artery occlusion. The electrocardiogram, left ventricular (LV) pressure, LV dP/dt, and aortic blood flow were recorded simultaneously. Baseline myocardial resistivity depicted a phasic pattern during the cardiac cycle with higher values at the preejection period (4.19 ± 1.09% increase above the mean, P < 0.001) and lower values during relaxation phase (5.01 ± 0.85% below the mean, P < 0.001). Acute coronary occlusion induced two effects on the phasic resistivity curve: 1) a prompt (5 min ischemia) holosystolic resistivity rise leading to a bell-shaped waveform and to a reduction of the area under the LV pressure-impedance curve (1,427 ± 335 vs. 757 ± 266 O·cm·mmHg, P < 0.01, 41 kHz) and 2) a subsequent (5–10 min ischemia) progressive mean resistivity rise (325 ± 23 vs. 438 ± 37 O·cm at 30 min, P < 0.01, 1 kHz). The structural and mechanical myocardial dysfunction induced by acute coronary occlusion can be recognized by specific changes in the systolic-diastolic myocardial resistivity curve. Therefore these changes may become a new indicator (surrogate) of evolving acute myocardial ischemia
Abstract:	Peer Reviewed
Materia(s):	-Àrees temàtiques de la UPC::Enginyeria biomèdica::Electrònica biomèdica -Impedance (Electricity) -Cardiology -- Research -Electrical Bioimpedance -Hemodynamics -Myocardial ischemia -Impedància (Electricitat) -Cardiologia -- Investigació
Derechos:	http://creativecommons.org/licenses/by-nc-nd/3.0/es/
Tipo de documento:	Artículo - Versión presentada Artículo
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