PMC9639676_01
(A) 12 lead ECG with standard lead placement showing sinus rhythm with a heart rate of 68 beats per minute. ECG revealed inverted P-QRS-T complex waves in lead I and inverted P-QRS in lead aVL. Notably, the P-QRS-T complex in lead aVR and aVL appear reversed compared to their usual relationship. Likewise, the morphology of the P-QRS-T complex of lead II and III was also invertedly compared to their usual relationship. The ECG shows an RS morphology in V1, a reversed R wave from V2 to V6 leads, a shortened P-R interval, and a characteristic "delta" wave. (B) 12 lead ECG with reverse lead placement and right precordial leads V3R-V6R. The ECG showed a positive P-QRS complex in lead I. The morphology of the P-QRS-T complex of lead aVR and aVL, lead II, and III were reversed compared to their morphologies in panel (A). R wave amplitude increases gradually, and the S wave decreases gradually in the precordial leads and the "delta" wave in 12 leads.
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F1
The EGM shows an RS morphology in V1, a reversed R wave from V2 to V6, a shortened P-R interval, and a characteristic "delta" wave (a wide and initially slurred QRS complex) in precordial leads (Figure 1A). Figure 1A. Furthermore, the R wave amplitude increased gradually, and the S wave decreased gradually in the precordial leads (Figure 1B).
The PA view chest X-ray shows shadows of the heart and aortic arch in the right hemithorax along with gas in the fundus of the stomach on the right side.
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F2
The X-ray image of mirror dextrocardia in the left anterior oblique view of 45  and right-anterior oblique view of 35 . (A) The image of dextrocardia in the left anterior oblique is presented as a common heart in the regular right anterior oblique. (B) The image of dextrocardia in the right anterior oblique is presented as a common heart in the regular left anterior oblique.
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F3
Smart touch catheter was introduced to the region of His-bundle from SL1 (Figure 3). Supraventricular tachycardia was induced with the frequency of 180 beats per minute by ventricular S1S1, and A was reset by right ventricular apex entrainments and RS2 stimuli.
(A) CARTO electroanatomical 3-dimensional(3D) mapping system showing the right atrium is a mirror image of a normal heart in the right-anterior oblique view(RAO)and the left-anterior oblique view (LAO). (B) ECG (before RFCA) with reverse lead placement and right precordial leads V3R-V6R shows an inferoseptal tricuspid annulus accessory pathway. The prominent early V wave in 7/8 bipolar potentials of 10 polar coronary sinus electrodes also indicates the accessory pathway was in the inferoseptal nearby the coronary sinus ostium. Ventricular activation was marked by the red arrow. (C) The ECG after the radiofrequency catheter ablation shows "delta" wave disappeared, indicating that the procedure was successful.
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F4
The patient was diagnosed with dextrocardia with a posteroseptal tricuspid annulus accessory pathway by the intracardiac EGM (Figures 4A,B). Delta wave disappeared on intracardiac and surface EGM (Figure 4C).
No characteristic "delta" wave was seen, and normal R/S transition was shown in precordial leads in 12 lead ECG with reverse lead placement.
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F5