Background: Patients who develop critical arrhythmia during left ventricular assist\ndevice (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart\nabnormalities, new heart-monitoring methods are required for patients supported\nby LVAD perfusion. Ventricular electrocardiography using electrodes implanted in\nthe ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left\nventricular impedance (LVI) is useful for monitoring heart movement but does not\nshow abnormal action potential in the heart muscle.\nObjectives: To detect detailed abnormal heart conditions, we obtained ventricular\nelectrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected\nto LVADs.\nMethods: In the porcine models, electrodes were set on the heart apex and\nascending aorta for real-time measurements of v-ECGs and LVI. As the carrier\ncurrent frequency of the LVI was adjusted to 30 kHz, it was easily derived from the\noriginal v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs\nwith a frequency band of 0.1 ââ?¬â?? 120 Hz were easily derived using a low-pass filter.\nSimultaneous v-ECG and LVI data were compared to detect heart volume changes\nduring the Q-T period when the heart contracted. A new real-time algorithm for\ncomparison of v-ECGs and LVI determined whether the porcine heartbeats were\nnormal or abnormal. Several abnormal heartbeats were detected using the LVADs\noperating in asynchronous mode, most of which were premature ventricle contractions\n(PVCs). To evaluate the accuracy of the new method, the results obtained were\ncompared to normal ECG data and cardiac output measured simultaneously using\ncommercial devices.\nResults: The new method provided more accurate detection of abnormal heart\nmovements. This method can be used for various heart diseases, even those in\nwhich the cardiac output is heavily affected by LVAD operation.
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