Cardiac Electromechanical Activity in Healthy Cats and Cats with Cardiomyopathies

Figures

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  Figure 1. Three manually inserted synchronization pulses at the beginning of the recording. An equivalent set of three pulses is also inserted at the end of the recordings. The synchronization time instant for ECG and PCG recordings is taken at the beginning of pulse No. 3 at the beginning and end of the recordings. Each synchronization pulse is generated by a key-press and key-release of the switch. In the PCG channel, the key-press produces an oscillation waveform, as shown in the inserted picture, where the start of the oscillation is used as the synchronization time instant.

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  Figure 2. Unfiltered and filtered versions of the lead III in the ECG. The filtered version of the lead was used to define the end of the T wave (T end) as the intersection of a tangent to the descending part of the T wave with a line representing the local baseline. For the beginning of the QRS, the unfiltered version of the lead was used.

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  Figure 3. Matched ECG and PCG recordings. The onset of mechanical systole (onset of tone S1) always starts later than the onset of electrical systole (onset of QRS) by the interval of electromechanical activation time (EMAT). Also, the beginning of tone S2 (end of mechanical systole) in this case is behind the end of electrical systole (end of T wave). Therefore, the electromechanical window (EMW) has a positive value.

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  Figure 4. Electromechanical intervals electromechanical activation time (EMAT) and electromechanical window (EMW) for two consecutive heartbeats in a cat with cardiomyopathy and long QRS (here 50 and 48 ms). Note that the intervals measured in the ECG between the two heartbeats (RR interval) and between S1 and S2 beats have the same value (342 ms). The variability of the EMAT and EMW intervals is not greater than the temporal resolution of the ECG recording (2 ms).