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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

Signal processing for the detection of abnormal heart beats (a) the v-ECG recorded from the in-vivo experiment, (b) the R-T period determined by the v-ECG in Figures 2 a, b, (c) the measured changes in LVI, (d) the magnitude of change in LVI during the R-T period, as measured in Figure 2 c, (e) the period during which blood flowed into the VAD, (f) the predicted increase in impedance during mean blood flow and inflow from the heart when the R-T period and increase in volume appeared to predict high impedance and (g) comparison of the predicted impedance in Figure 3 f and the actual LVI increase in Figure 3 d.
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Fig3: Signal processing for the detection of abnormal heart beats (a) the v-ECG recorded from the in-vivo experiment, (b) the R-T period determined by the v-ECG in Figures 2 a, b, (c) the measured changes in LVI, (d) the magnitude of change in LVI during the R-T period, as measured in Figure 2 c, (e) the period during which blood flowed into the VAD, (f) the predicted increase in impedance during mean blood flow and inflow from the heart when the R-T period and increase in volume appeared to predict high impedance and (g) comparison of the predicted impedance in Figure 3 f and the actual LVI increase in Figure 3 d.

Mentions: The v-ECG in Figure 3 (a) was obtained from the in-vivo experiment. It showed distinct R-waves and T-waves on the v-ECG whether the heart beat were normal or abnormal. However, many abnormal heart beats could not be identified with only the v-ECG; although these abnormal signals could be found by analyzing the conventional ECG signal measured at the same time (Figure 4 (a)). The R-T period could be calculated with the v-ECG by measuring the delay from the R-wave to the T-wave according to the algorithm shown in Figure 2 (a) and (b). The R-T period is shown in Figure 3 (b) and the y-axis of Figure 3 (b) shows the average blood flow during the R-T period. Outside of the R-T period, the aortic valve was assumed to be closed and the blood flow ceased.Figure 3


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)

Signal processing for the detection of abnormal heart beats (a) the v-ECG recorded from the in-vivo experiment, (b) the R-T period determined by the v-ECG in Figures 2 a, b, (c) the measured changes in LVI, (d) the magnitude of change in LVI during the R-T period, as measured in Figure 2 c, (e) the period during which blood flowed into the VAD, (f) the predicted increase in impedance during mean blood flow and inflow from the heart when the R-T period and increase in volume appeared to predict high impedance and (g) comparison of the predicted impedance in Figure 3 f and the actual LVI increase in Figure 3 d.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig3: Signal processing for the detection of abnormal heart beats (a) the v-ECG recorded from the in-vivo experiment, (b) the R-T period determined by the v-ECG in Figures 2 a, b, (c) the measured changes in LVI, (d) the magnitude of change in LVI during the R-T period, as measured in Figure 2 c, (e) the period during which blood flowed into the VAD, (f) the predicted increase in impedance during mean blood flow and inflow from the heart when the R-T period and increase in volume appeared to predict high impedance and (g) comparison of the predicted impedance in Figure 3 f and the actual LVI increase in Figure 3 d.
Mentions: The v-ECG in Figure 3 (a) was obtained from the in-vivo experiment. It showed distinct R-waves and T-waves on the v-ECG whether the heart beat were normal or abnormal. However, many abnormal heart beats could not be identified with only the v-ECG; although these abnormal signals could be found by analyzing the conventional ECG signal measured at the same time (Figure 4 (a)). The R-T period could be calculated with the v-ECG by measuring the delay from the R-wave to the T-wave according to the algorithm shown in Figure 2 (a) and (b). The R-T period is shown in Figure 3 (b) and the y-axis of Figure 3 (b) shows the average blood flow during the R-T period. Outside of the R-T period, the aortic valve was assumed to be closed and the blood flow ceased.Figure 3

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