Case report
A female patient, 66 years old, was admitted to the hospital with the
chief complaint of ”intermittent palpitation accompanied by chest
tightness for 11 years, aggravated for 1month”. Previous history of
hypertension for 3 months and coronary artery disease for 1 month..
12-lead ECG (Figure 1A) indicates sinus rhythm, 24h ambulatory ECG
indicates atrial tachycardia (narrow QRS tachycardia). Chest radiographs
(Figure 1B) and cardiac CTA (Figure 1D) suggest dextrocardia and atrial
septal aneurysm. The echocardiogram (Figure 1C) showed the patient had a
mirror dextrocardia, right aortic arch, left atrium 34 mm, left
ventricular diastolic 47 mm, and right atrium 35 mm. Transesophageal
echocardiography showed no thrombus formation in the left atrial
appendage, which was thinner in the middle of the atrial septum between
the left and right atrial, and expanded to the right atrial side, with a
maximum depth of about 17mm. Conventional 12-lead ECG and CTA of the
left atrial pulmonary vein simultaneously suggested dextrocardia (Figure
1). The patient had been taking medication, but the medication was
ineffective. Transcatheter cardiac radiofrequency ablation was performed
with the consent of the patient and his family.
The patient was lying flat on the operating table, electrocardiogram,
blood pressure and oxygen monitoring, the operating area was routinely
disinfected and toweled, 2% lidocaine was used to locally infiltrate
the puncture area and after the anesthesia took effect, the right
femoral vein was punctured and an 11F sheath was placed, the ultrasound
probe was sent along the 11F sheath to the middle of the right atrium to
clarify the special spatial structure of the heart, whether there was
thrombosis in the left atrial appendage, and to guide the atrial septal
puncture as fellows (Figure 2). The left and right femoral veins were
then punctured, and a 6F sheath was placed on the left side and a 7.5F
sheath on the right side. A 10-pole electrode was placed in the coronary
sinus through the left venous sheath under fluoroscopy, and a 4-pole
electrode was placed in the right ventricular apex through the right
femoral vein. Electrophysiological examination: S1S1 stimulating was
administrated to CS 7-8, Wenckebach point was 280ms, once S1S1 was
decreased to 210ms, narrow QRS tachycardia was induced. The earliest
atrial activation was measured in CS 7-8, TCL was 310ms, with 1:1
atrioventricular conduction. Further entrainment with RV S1S1 290ms was
administrated, the interval of atrioventricular remained the same, the
cycle length of A-A interval was still 310ms, indicating the arrhythmia
was atrial tachycardia. Then the ablation head was sent to the right
atrium through the venous sheath for high-precision mapping. The results
showed that the earliest activation point of the right atrium was
located near the His bundle, suggesting that the earliest activation
point of the right atrium was not from the right atrium. This leads one
to consider whether the origin of the earliest activation is from the
anatomically adjacent region, such as the left atrium and non-coronary
sinus. Further atrial septal puncture was required, because the patient
was complicated with atrial septal aneurysm. The difficulty and risk of
atrial septal puncture will be greatly increased in dextrocardia if only
traditional image positioning was used for atrial septal puncture, which
further reflects the importance of ICE. Under the guidance of ICE, we
fully reconstructed the structure of the left atrium, and selected the
weaker middle part of the atrial septum for puncture (figure). After
success, a multi-electrode mapping catheter was used to perform
high-precision mapping of the left atrium under atrial tachycardia. The
mapping results indicated that the anterior septum of the left atrium
and the aortic indentation were the earliest activation areas, which is
adjacent to the earliest area of the right atrium, and the activation
time is about 30ms ahead of the earliest right atrium, and the local
activation time is 55ms ahead of the reference zero point (Figure).
Attempt to ablate with a power mode of 30W, the atrial tachycardia has
not been terminated, suggesting that the ablation was ineffective,
consider mapping anatomically adjacent parts: no coronary sinus. The
right femoral artery was punctured, and the earliest activated
conduction potential was traced at the bottom of the non-coronary sinus,
and the local activated time was 80ms ahead of the reference zero point.
Titrated ablation in the power mode of 25-40W, the atrial tachycardia
was terminated immediately after ablation, the patient recovered sinus
rhythm, and the ablation was consolidated for 60 seconds. No junctional
rhythm and prolongation of the atrioventricular interval were observed
during the ablation process (Figure). After the ablation, repeating the
previous induction conditions and repeated high-frequency atrial and
coronary sinus stimulation did not induce any form of arrhythmia.
Intracardiac ultrasonography was used to detect the pericardium, and the
operation ended after confirming safety. At 3-month postoperative
follow-up, the patient’s panic symptoms disappeared and no atrial
tachycardia was seen on the repeat ambulatory electrocardiogram.