The combined use of esophageal electrocardiogram and multiple right parasternal chest leads in the diagnosis of PSVT and determination of accessory pathways involved: A new simple noninvasive approach

The optimal lead insertion depth for esophageal ECG recordings with respect to atrial signal quality

BACKGROUND

Diagnosing supraventricular arrhythmias by conventional long-term ECG can be cumbersome because of poor p-waves. Esophageal long-term electrocardiography (eECG) has an excellent sensitivity for atrial signals and may overcome this limitation. However, the optimal lead insertion depth (OLID) is not known.

METHODS

We registered eECGs at different lead insertion depths in 27 patients and analyzed 199,716 atrial complexes with respect to signal amplitude and slope. Correlation and regression analyses were used to find a criterion for OLID.

RESULTS

Atrial signal amplitudes and slopes significantly depend on lead insertion depth. OLID correlates with body height (rSpearman=0.71) and can be estimated by OLID [cm]=0.25*body height[cm]-7cm. At this insertion depth, we recorded the largest esophageal atrial signal amplitudes (1.27±0.86mV), which were much larger compared to conventional surface lead II (0.19±0.10mV, p<0.0001).

CONCLUSION

The OLID depends on body height and can be calculated by a simple regression formula.

Oesophageal electrocardiography in healthy horses

REASONS FOR PERFORMING STUDY

In human medicine, oesophageal electrocardiography (ECG) is a well-established technique that magnifies P waves with respect to the QRS complex.

OBJECTIVES

To investigate the feasibility of oesophageal ECG recording in horses and its ability to produce larger P waves compared with base-apex and unipolar recordings.

METHODS

Bipolar and unipolar ECG were performed using oesophageal and surface electrodes. Oesophageal ECG was obtained from 6 different recording configurations at different oesophageal depths. Amplitudes of P, Q, R, S and T waves were measured from 3 different cardiac cycles for each recording configuration and depth.

RESULTS

Oesophageal ECG was feasible in all horses. For all oesophageal recording configurations, significantly larger P waves were recorded from a depth that equalled 'height of the withers + 10 cm' (HW(+10) ) than from any other depth. P/QRS(magn), the ratio between the P wave and QRS complex magnitudes, was largest for intraoesophageal recordings with an interelectrode distance of 10 cm, at HW(+10), where it was significantly larger than base-apex and unipolar recordings. Base-apex recording resulted in significantly smaller P waves than all other recording configurations and significantly smaller P/QRS(magn) ratios than all other recording configurations except one combined oesophageal-surface recording (E/S(low)).

CONCLUSIONS

Oesophageal ECG recording is feasible in horses and effective in magnifying P wave amplitude.

POTENTIAL RELEVANCE

The procedure is promising for diagnosis of supraventricular tachydysrhythmias and might be used in electrophysiological studies and for cardiac pacing.