OBJECTIVE: Myocardial electrical impedance (MEI) has shown to be an effective indicator of myocardial ischemia. We have previously developed a novel monitor for measuring MEI in near-real time. The object of this study was to test whether drug-induced changes in the frequency of the periodic myocardial electrical activity, as measured by the heart rate (HR), affect MEI measurements made with our monitor. METHODS: Thirty dogs were randomly assigned to one of three study groups (placebo, isoproterenol or esmolol) and then anesthetized with sodium thiamylal, intubated, ventilated, given isoflurane, and had venous, arterial, and pulmonary artery catheters placed. Median sternotomy was performed to facilitate myocardial exposure and to allow the left anterior descending (LAD) coronary artery to be isolated. Following baseline measurements, saline (control), isoproterenol or esmolol was administered and the LAD coronary artery was occluded in a timed sequence in order to study the effects of heart rate changes and demonstrate induced myocardial ischemia on MEI. RESULTS: Isoproterenol raised the HR and esmolol lowered the HR without affecting our MEI measurements. Myocardial electrical impedance increased during LAD coronary artery occlusion in all groups, as previously shown. CONCLUSION: These results demonstrate that our MEI monitor is unaffected by the frequency of the periodic myocardial electrical activity that generates the HR.
OBJECTIVE: Myocardial electrical impedance (MEI) has shown to be an effective indicator of myocardial ischemia. We have previously developed a novel monitor for measuring MEI in near-real time. The object of this study was to test whether drug-induced changes in the frequency of the periodic myocardial electrical activity, as measured by the heart rate (HR), affect MEI measurements made with our monitor. METHODS: Thirty dogs were randomly assigned to one of three study groups (placebo, isoproterenol or esmolol) and then anesthetized with sodium thiamylal, intubated, ventilated, given isoflurane, and had venous, arterial, and pulmonary artery catheters placed. Median sternotomy was performed to facilitate myocardial exposure and to allow the left anterior descending (LAD) coronary artery to be isolated. Following baseline measurements, saline (control), isoproterenol or esmolol was administered and the LAD coronary artery was occluded in a timed sequence in order to study the effects of heart rate changes and demonstrate induced myocardial ischemia on MEI. RESULTS:Isoproterenol raised the HR and esmolol lowered the HR without affecting our MEI measurements. Myocardial electrical impedance increased during LAD coronary artery occlusion in all groups, as previously shown. CONCLUSION: These results demonstrate that our MEI monitor is unaffected by the frequency of the periodic myocardial electrical activity that generates the HR.
Authors: Roger Dzwonczyk; Carlos L del Rio; Chittoor Sai-Sudhakar; John H Sirak; Robert E Michler; Benjamin Sun; Nicole Kelbick; Michael B Howie Journal: Eur J Cardiothorac Surg Date: 2006-10-17 Impact factor: 4.191
Authors: O Grauhan; J Müller; C Knosalla; T Cohnert; H Siniawski; H D Volk; E Fietze; W Kupetz; R Hetzer Journal: J Heart Lung Transplant Date: 1996-02 Impact factor: 10.247
Authors: Roger Dzwonczyk; Carlos del Rio; David A Brown; Robert E Michler; Randal K Wolf; Michael B Howie Journal: IEEE Trans Biomed Eng Date: 2004-12 Impact factor: 4.538
Authors: Vincenzo Lionetti; Simone Lorenzo Romano; Giacomo Bianchi; Fabio Bernini; Anar Dushpanova; Giuseppe Mascia; Martina Nesti; Franco Di Gregorio; Alberto Barbetta; Luigi Padeletti Journal: PLoS One Date: 2013-11-19 Impact factor: 3.240