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Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.

Her K, Ahn CB, Park SM, Choi SW - Biomed Eng Online (2015)

Bottom Line: Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle.Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted.To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular and Thoracic Surgery, Soonchunhyang University Hospital, Bucheon-si, South Korea. hktree@schmc.ac.kr.

ABSTRACT

Background: Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle.

Objectives: To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs.

Methods: In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices.

Results: The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.

No MeSH data available.


Related in: MedlinePlus

Algorithm for (left) detection of R-T impedance increases, (right) VAD operation conditions, and (middle and bottom) comparison of R-T impedance and prediction. (a) the R-wave detection in v-ECG, (b) the T-wave detection, (c) the calculation of LVI change during R-T period, (d) the prediction of volume change from v-ECG and LVAD inflow, (e) the impedance prediction, (f) the result of low-pass filter and (g) the comparison of the predicted value and the measured.
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Fig2: Algorithm for (left) detection of R-T impedance increases, (right) VAD operation conditions, and (middle and bottom) comparison of R-T impedance and prediction. (a) the R-wave detection in v-ECG, (b) the T-wave detection, (c) the calculation of LVI change during R-T period, (d) the prediction of volume change from v-ECG and LVAD inflow, (e) the impedance prediction, (f) the result of low-pass filter and (g) the comparison of the predicted value and the measured.

Mentions: Figure 2 shows the algorithms for real-time analysis of v-ECGs and LVI measurements from a LVAD to monitor changes in heart activity. The left side of the algorithm shows the following sequence: (1) measure the v-ECG and LVI; (2) use the same algorithm to measure R-wave and T-wave; then (3) derive the change in LVI in the R-T period. The middle section shows the algorithm for calculating the change in impedance using the onset times of R- and T-waves, cardiac output (CO), and the duration and volume of influx into the LVAD. The right section shows the algorithm for sending the LVAD blood influx time and volume data to the impedance calculating algorithm [17]. Finally, abnormal pulses are distinguished by comparing the predicted impedance to the LVI value in the R-T period.Figure 2


Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.

Her K, Ahn CB, Park SM, Choi SW - Biomed Eng Online (2015)

Algorithm for (left) detection of R-T impedance increases, (right) VAD operation conditions, and (middle and bottom) comparison of R-T impedance and prediction. (a) the R-wave detection in v-ECG, (b) the T-wave detection, (c) the calculation of LVI change during R-T period, (d) the prediction of volume change from v-ECG and LVAD inflow, (e) the impedance prediction, (f) the result of low-pass filter and (g) the comparison of the predicted value and the measured.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374380&req=5

Fig2: Algorithm for (left) detection of R-T impedance increases, (right) VAD operation conditions, and (middle and bottom) comparison of R-T impedance and prediction. (a) the R-wave detection in v-ECG, (b) the T-wave detection, (c) the calculation of LVI change during R-T period, (d) the prediction of volume change from v-ECG and LVAD inflow, (e) the impedance prediction, (f) the result of low-pass filter and (g) the comparison of the predicted value and the measured.
Mentions: Figure 2 shows the algorithms for real-time analysis of v-ECGs and LVI measurements from a LVAD to monitor changes in heart activity. The left side of the algorithm shows the following sequence: (1) measure the v-ECG and LVI; (2) use the same algorithm to measure R-wave and T-wave; then (3) derive the change in LVI in the R-T period. The middle section shows the algorithm for calculating the change in impedance using the onset times of R- and T-waves, cardiac output (CO), and the duration and volume of influx into the LVAD. The right section shows the algorithm for sending the LVAD blood influx time and volume data to the impedance calculating algorithm [17]. Finally, abnormal pulses are distinguished by comparing the predicted impedance to the LVI value in the R-T period.Figure 2

Bottom Line: Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle.Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted.To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular and Thoracic Surgery, Soonchunhyang University Hospital, Bucheon-si, South Korea. hktree@schmc.ac.kr.

ABSTRACT

Background: Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle.

Objectives: To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs.

Methods: In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices.

Results: The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.

No MeSH data available.


Related in: MedlinePlus