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Fig.5
ICG wave amplitudes for control subjects and patients with mitral insufficiency (mean± SD)
| ICG waves | Control subjects | Patients with MI | t–values |
|---|---|---|---|
| O (Ohm/s)∙10-3 | 1.2±1.2 | 5.3±0.4 | 14.4* |
| A (Ohm/s)∙10-3 | -1.5 ± 0.2 | -20±0.004 | 403.5* |
| I (Ohm/s)∙10-3 | 2.7 ± 1.5 | 25.3 ± 0.4 | 63.24* |
Characteristic points on the ICG signal
| Characteristic points | Description |
|---|---|
| A | Is the beginning of electromechanical systole. It is associated with the atrial contraction. |
| B | Appears simultaneously with the opening of the aortic valve. The precise identification of a B point is important for accurate calculation of stroke volume and cardiac output [33]. It denotes the beginning of the ejection time. It has been reported that the marker of this point is not always apparent [34] and it may occur at any point on the ascending portion of the signal before the (dZ/dt) max [35, 36]. |
| C | Is taken at the peak of the ICG signal and it corresponds to the ventricular contraction. The amplitude of this point is used to calculate the stroke volume and cardiac output. |
| X | Is the lowest point after the peak and it is associated with the closure of the aortic valve. It indicates the end of the systole [37]. |
| O | Is associated with changing of the volume during the diastolic phase of the cycle and the maximal opening of the mitral valve [37]. |
The computed hemodynamic parameters for control subjects and patients with mitral insufficiency (mean± SD)
| ICG waves | Control subjects | Patients with MI | t–values |
|---|---|---|---|
| HR (bpm) | 58±3 | 58±7 | n/s |
| LVET (ms) | 270 ± 110 | 500±76 | 7.50* |
| SV (ml) | 113.8 ± 17.5 | 70.7 ± 12.2 | 8.81* |
| CO (l/min) | 6.6±0.8 | 4.1±1.1 | 8.07* |
ROC curve analysis of O-wave amplitude, A-wave amplitude, and the characteristic parameter “I”
| Amplitude (Ohm/s) | AUC | P | Optimum cut-off | Se (%) | Sp (%) | PPV (%) | NPV (%) |
|---|---|---|---|---|---|---|---|
| O | 0.96 | <0.0001 | >3.64 | 70 | 100 | 100 | 96.8 |
| A | 1 | <0.0001 | ≤ -20 | 100 | 100 | 100 | 100 |
| I | 1 | <0.0001 | >5.44 | 100 | 100 | 100 | 100 |