Dependence of temporal variability of ventricular recovery on myocardial fibrosis. Role of mechanoelectric feedback?

Objective: The study was aimed at establishing the effect of factors involved in the expression of mechanoelectric feedback in the heart, such as R-R interval and connective tissue, on time dependent changes in ventricular recovery, as determined at the body surface by beat to beat variability of QRST integral maps (BBV-IM).

Methods: We used 15 normal 6-month-old Wistar rats. In each anesthetized animal, we performed a 3-minute continuous recording of 44.

Electrode positioning for reliable telemetry ECG recordings during social stress in unrestrained rats.

We describe a surgical procedure for optimizing the location of telemetry ECG leads in rats. The new location was aimed at obtaining an accurate representation of ECG features throughout the cardiac cycle by limiting the voltage instability usually observed during intense somatomotor activity and improving the signal-to-noise ratio. The two electrodes (wire loops) were fixed on the dorsal surface of the xiphoid process and in the anterior mediastinum close to the right atrium.

Behavioral and electrocardiographic responses to social stress in male rats.

Telemetry ECGs were recorded from Wistar male rats during social stress induced by exposure to aggressive lactating female rats. Behavioral response to maternal attack was evaluated in terms of relative duration of passive submissive (p/s) and active/nonsubmissive (a/ns) patterns. A decrease of R-R interval (R-R) compared to baseline conditions was found, significantly more pronounced than that observed in control animals exposed just to novel environment.

Diagnostic features of body surface potential maps in patients with myocardial ischemia and normal resting 12-lead electrocardiograms.

Body surface maps recorded from 35 ischemic patients with normal resting 12-lead electrocardiograms were compared with those obtained from 36 age- and sex-matched normal subjects. From instantaneous maps of each subject 187 variables were derived relating to the configuration (80 variables) and magnitude (104 variables) of the potential distribution and duration of the electrocardiographic intervals (3 variables). By using stepwise discriminant analysis we selected 3 variables whose linear combination enabled us to correctly allocate 91% of the study population (jacknife procedure; specificity 92%, sensitivity 91%).