Fig 1.
Cardiac-cycle synchronized belt electrode skeletal muscle electrical stimulation (C-B-SES) system for humans.
(A) Four belt electrodes connected to the special device (white arrow) were wrapped around bilateral distal parts of the thigh and crus of the subject. The special device was linked to the electrocardiogram (ECG) recorder device (white arrowhead) through the special code. Written informed consent was obtained from the subject for publication of this picture. (B) Three electrodes pasted on the precordia of the subject were connected to the ECG recorder device to collect the ECG data. After collecting the data, they were sent to the special device and then C-B-SES was provided to the lower limbs. The special device combined the ECG data analysis, trigger signal generation, and electrical signal output for C-B-SES.
Fig 2.
Synchro-time of C-B-SES on electrocardiogram (ECG) and phonocardiogram (PCG).
P, R, and T indicate the P wave, R wave, and T wave of the ECG, respectively. I and II indicate the sound of the closing of the mitral and aortic valves, respectively. RR-1 and RR-2 indicate the interval time between the tops of the two R waves. RT-1 and RT-2 indicate the trigger signal generation time between the top of the R wave (red dashed line) and the synchro-time (blue dashed line under the black diamond). The black diamond indicates the time phase of C-B-SES on the ECG and PCG charts.
Fig 3.
Representative plethysmography waveform charts during C-B-SES with heart assist effects.
The chart displays ECG, PCG, and plethysmogram (PTG) together. The PTG waveforms are derived from bilateral brachial artery (BA) pulsation. I and II indicate the sound of the closing of the mitral and aortic valves, respectively. The black dashed line circle indicates a dicrotic notch corresponding to the acute drop following the systolic peak of the arterial pressure pulse wave. The notch coincides with the aortic valve closure. The red arrow indicates a diastolic augmentation wave on the dicrotic notch. The blue arrow indicates an end-diastolic pressure reduction wave. The end-diastolic pressure following C-B-SES was lower than the preceding unassisted end-diastolic pressure (blue dashed line).
Fig 4.
Representative plethysmography waveform charts during C-B-SES without desirable heart assist effects.
Although we tested a 1:1 heart assist C-B-SES in each synchro-time adopted in order from 10 values between 0.05 and 0.45, desirable diastolic augmentation waves on the dicrotic notches or end-diastolic pressure reduction waves were not observed in all values (the center and right panels show the charts at 0.1 and 0.35 synchro-times, respectively). Despite the small change, there might be diastolic augmentation waves on the dicrotic notches (red arrows).
Fig 5.
Trends of hemodynamic changes in the absence or presence of C-B-SES to the lower limbs.
The blood pressure was measured by the plethysmography. The heart rate, stroke volume, and cardiac output were measured by the percutaneous analyzer. The peripheral vascular resistance was calculated using the value of the blood pressure and stroke volume. Trends in 11 subjects are shown by a bar-graphic representation for each subject. Each value expressed by a gray or red bar graph was the value in testing whether each adopted synchro-time was suitable for ideal C-B-SES. The red bar graph indicates the value when we achieved an ideal C-B-SES whose plethysmography wave pattern was comparable with the pattern of IABP. The blue and yellow bar graphs indicate the values before and after the test, respectively. The ideal C-B-SES was not achieved in subjects #10 and #11. The values of blue and red bar graphs correspond to the values of ‘OFF’ and ‘ON’ in Table 1, respectively.
Table 1.
Hemodynamic changes in the absence or presence of C-B-SES controlled by the suitable synchro-time.
Fig 6.
Representative plethysmography waveform chart in an ideal 1:2 heart assist IABP.
The plethysmogram (PTG) waveforms are derived from bilateral brachial artery (BA) pulsation. The red arrow indicates a diastolic augmentation wave on the dicrotic notch (black dashed line circle). The blue arrow indicates an end-diastolic pressure reduction wave. The end-diastolic pressure following IABP was lower than the preceding unassisted end-diastolic pressure (blue dashed line). In addition, the systolic pressure following IABP was lower than the previous unassisted systolic pressure (green arrow and dashed line).