CineECG provides a novel anatomical view on the normal atrial P-wave

Interactive teaching of medical 3D cardiac anatomy: atrial anatomy enhanced by ECG and 3D visualization

The most commonly applied way of teaching students to convey the foundations of human anatomy and physiology involves textbooks and lectures. This way of transmitting knowledge causes difficulties for students, especially in the context of three-dimensional imaging of organ structures, and as a consequence translates into difficulties with imagining them. Even despite the rapid uptake of knowledge dissemination provided by online materials, including courses and webinars, there is a clear need for learning programs featuring first-hand immersive experiences tailored to suit individual study paces. In this paper, we present an approach to enhance a classical study program by combining multi-modality data and representing them in a Mixed Reality (MR)-based environment. The advantages of the proposed approach have been proven by the conducted investigation of the relationship between atrial anatomy, its electrophysiological characteristics, and resulting P wave morphology on the electrocardiogram (ECG). Another part of the paper focuses on the role of the sinoatrial node in ECG formation, while the MR-based visualization of combined micro-computed tomography (micro-CT) data with non-invasive CineECG imaging demonstrates the educational application of these advanced technologies for teaching cardiac anatomy and ECG correlations.

CineECG for visualization of changes in ventricular electrical activity during ischemia

BACKGROUND

CineECG offers a visual representation of the location and direction of the average ventricular electrical activity throughout a single cardiac cycle, based on the 12‑lead ECG. Currently, CineECG has not been used to visualize ventricular activation patterns during ischemia.

PURPOSE

To determine the changes in ventricular activity during acute ischemia with the use of CineECG, and relating this to changes in the ECG.

METHODS

Continuous ECG's during percutaneous coronary intervention with prolonged balloon inflation from the STAFF III database were analyzed with CineECG at baseline and every 10 s throughout the first 150 s of balloon inflation. The CineECG direction was determined for the initial QRS-complex, terminal QRS-complex, ST-segment and T-wave. Changes in the CineECG were quantified by calculating the Δangle between the direction at baseline and the direction at every 10 s of inflation. Additionally, the root mean square amplitude (rmsA) of the ST-segment was computed.

RESULTS

94 patients were included. At start inflation, the median Δangle was 14.7° [7.5-33.4], 21.8° [11.4-34.2], 20.6° [8.0-43.9], and 23.5° [11.8-48.0] for the initial QRS-complex, terminal QRS-complex, ST-segment and T-wave, respectively. Meanwhile, the median rmsA increased from 0.039 mV [0.027-0.058] at baseline to 0.045 mV [0.033-0.075] at start of inflation.

CONCLUSIONS

CineECG was able to detect immediate changes in ventricular electrical activity during induced ischemia, while changes in the ST-segment of the ECG were still subtle. Therefore, CineECG might support the early detection of acute ischemia, even before distinct ECG changes become visible.

Case report: Widely split P' waves in a patient with focal atrial tachycardia

Background

Widely split P waves in sinus rhythm have been reported previously. However, widely split P' waves in focal atrial tachycardia (AT) on a surface electrocardiogram (ECG) have rarely been reported. The electrophysiological mechanism is relatively difficult to clarify, requiring a electrophysiological study.

Case summary

A 67-year-old patient, who had undergone two radiofrequency ablations for atrial fibrillation, presented with recurrent palpitation. During the palpitation episode, the 12-lead ECG showed AT with a 3:1 atrioventricular conduction rate. P' waves were markedly prolonged in duration and widely split in morphology. An electrophysiological study showed that the tachycardia arose from the left atrial appendage (LAA) and was conducted through two distinct pathways. The impulse of one pathway was transmitted solely via the superior part of the atrium, including the Bachmann bundle. The second pathway was conducted via the coronary sinus and transmitted the impulse from the LAA to the ventricle. After the site showed that the earliest activation was ablated, repeated intravenous infusion of isoprenaline and programmed atrial stimulation did not induce tachycardia.

Conclusion

Widely split P' waves in AT indicate intra- and interatrial conduction blocks, which can be easily overlooked due to the presence of low-voltage areas. Therefore, an electrophysiological study is crucial for identifying the origin of the tachycardia and elucidating the mechanistic details.