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a 31-year old female presented with palpitations during the first trimester of her pregnancy and was found to have an incessant long rp supraventricular tachycardia ( svt ) .
her echo initially showed mild lv systolic dysfunction , normal biatrial / biventricular size and no valvular abnormalities .
she was commenced on beta blockers , but her svt persisted with poorly controlled rates .
amiodarone was then started and she was electrically cardioverted after a 2 week load , but her tachycardia recurred within a few hours . the option of catheter ablation was discussed and she preferred to defer the procedure until after her delivery .
one month later , her lv ejection fraction had declined to 20% and holter showed incessant svt at 110140  bpm with variable av conduction despite amiodarone , high dose beta - blockade and digoxin . a second attempt at electrical cardioversion only transiently restored sinus rhythm .
she remained on amiodarone for the next 5 months of her pregnancy with close monitoring of her fetus and ventricular function .
she was induced at 35 weeks and her delivery was uncomplicated without hemodynamic compromise or clinical heart failure .
her tachycardia persisted postpartum and she was scheduled for catheter ablation . during her electrophysiology study , the svt initiated and terminated spontaneously with av nodal wenchebach .
p wave morphology during svt was biphasic ( positive / negative ) in lead v1 with an inferior axis suggesting a high right atrial ( ra ) origin ( fig .  1 ) .
lead v2 had a negative bifid p wave quite distinct from the positive p wave during sinus rhythm .
electroanatomic mapping ( carto 3 , biosense webster ) during svt demonstrated a focal origin in the ra appendage with centrifugal activation to the rest of the ra .
while mapping within the ra appendage , the tachycardia terminated at a site where the local atrial electrogram was 30  ms ahead of the p wave .
a single irrigated radiofrequency [ rf ] application [ power 20  w , 90  s , 8  cc / min saline ] was delivered to this site .
two months after ablation , she was again in incessant atrial tachycardia with the same p wave morphology and variable av conduction . with her lv ejection fraction remaining 20%
a ra appendage angiogram was performed with a multipurpose catheter which revealed a single lobed structure ( fig .  2 ) . using electroanatomic mapping ,
the site of earliest atrial activation was again localized to the lateral aspect of the distal tip of the ra appendage where local atrial electrogram was 20  ms ahead of p wave ( fig .  2 ) .
despite several irrigated rf applications to this site ( 2025  w , 8  cc / min saline ) and surrounding region , the tachycardia did not terminate or slow down .
poor catheter contact due to the dynamic movement of the ra appendage was felt to be a limitation to further rf application .
cryoablation was then attempted in a bid to attain better catheter contact throughout the cardiac cycle .
a freezor max 8  mm cryocatheter ( medtronic inc . ) was maneuvered to the tip of the ra appendage under fluoroscopic guidance and positioned at a site with local egm 20  ms ahead of surface p wave ( fig .  2 ) .
within 4  s of initiating cryoablation , the tachycardia terminated leaving sinus rhythm ( fig .  3 ) .
two cryoablation lesions ( 80  c , 4  min each ) were then delivered at the same site .
after a 6 month followup period , there was no tachycardia recurrence based on surveillance ecgs and holter recordings . a cardiac mri done 6 months postablation showed normalization of ventricular function and no late gadolinium enhancement .
we present , to our knowledge , the first case of incessant focal atrial tachycardia arising from the apex of the ra appendage which was successfully cryoablated with a solid tip catheter after failing conventional rf ablation .
focal atrial tachycardias from the ra appendage are uncommon with a prevalence of 3.8% and the commonest location within the ra appendage is the inferolateral base .
the ecg is usually characterized by a positive p wave in the inferior leads , negative in v1 , isoelectric / positive in lead i and isoelectric / negative in avr .
however , this p wave vector may also be seen with focal atrial tachycardias arising from the tricuspid annulus and the crista terminalis . in our patient ,
the p wave was biphasic in lead v1 ( positive / negative ) and lead i ( negative / positive ) .
the anatomy of the ra appendage is complex and presented technical challenges in our patient .
the lateral wall consists of ridges of pectinate muscles separated by thin membrane like walls with sparse myocardium .
the trabeculations of the pectinate muscles often restrict catheter mobility and maneuverability within the ra appendage . performing a ra appendage angiogram to clarify its anatomy and depth
our patient 's tachycardia focus was located on the thin lateral wall near the apex which may explain why a large portion of the proximal ra appendage showed equally early local atrial egms . in such situations , it is essential to carefully map more distally within the ra appendage .
our patient 's ablation was postponed until after her delivery as she was concerned about the potential risk of fetal radiation exposure despite our intention to use a low radiation dose protocol . the delay in ablation therapy and the ineffectiveness of amiodarone / electrical cardioversion led to a significant deterioration in ventricular function , thereby increasing the risk of fetal and maternal complications late in pregnancy and during delivery .
contemporary electroanatomic 3d mapping systems and intracardiac echocardiography can help to minimize radiation exposure and in some cases may obviate the need for fluoroscopy altogether .
ferguson et  al . reported successful radiofrequency ablation of a focal left atrial tachycardia using this approach with no fluoroscopy .
catheter ablation of focal tachycardias in the ra appendage using rf energy is often associated with recurrences as was evident in our patient . the small size and low cavitary blood of the ra appendage
in addition , the ra appendage is a highly mobile structure that limits consistent catheter contact during ablation , even with a steerable sheath .
our patient failed two attempts at rf ablation using irrigated catheters , which was felt to be due to poor catheter stability within the appendage .
as an alternative , surgical excision of the ra appendage to eliminate the focus ,   and cryoablation may have a role .
chun et  al . described the use of a cryoballoon to isolate the ra appendage when conventional rf within the ra appendage proved unsuccessful . in their case ,
the tachycardia focus was not eliminated , but rather dissociated from the rest of the ra .
the efficacy of cryoballoon therapy is highly dependent on suitable ra appendage anatomy and may not be possible in all patients with broad ra appendage bases or multiple lobes .
the isolated ra appendage may also increase the risk of thrombus formation due to loss of contractile drive from the sinus node . as an alternative , we chose the large 8  mm tipped cryocatheter with the intention of improving contact and increasing the probability of approximating the focal origin of the tachycardia .
in contrast to rf ablation where the catheter remains mobile during ablation , cryoablation is associated with freeze - mediated catheter adhesion to the target tissue .
firstly , freeze - mediated catheter stability facilitates ablation of sites where contact is difficult to maintain , like the ra appendage .
second , cryoadhesion eliminates the brushing effect seen with rf ablation , whereby rf energy is applied to the target and surrounding non - target tissue because of cardiac and respiratory motion .
it can be expected that increased catheter stability will result in less collateral damage to nearby critical structures such as the right coronary artery at the base of the ra appendage .
another advantage of cryoablation is the preservation of ultrastructural integrity , an observation that is attributed to the marked resilience of fibroblasts and collagen fibers to hypothermia .
preservation of tissue ultrastructural integrity should reduce the risk of perforation even in the ra appendage and our patient had no procedural complications following cryoablation .
the large surface area of the cryocatheter probably also makes it less likely to perforate . in summary , ra appendage focal tachycardia , though rare , tends to be incessant and needs to be aggressively managed in order to avoid tachycardia - cardiomyopathy .
cryoablation with a solid tip catheter may be more effective and safer than rf energy for ablation deep in the ra appendage owing to greater catheter stability and a lower likelihood of perforation .
the right atrial appendage can be the origin of focal atrial tachycardias . 
 their ablation can be challenging owing to the complexity of the appendage anatomy . to our knowledge 
 , we describe the first successful solid tip cryoablation of a focal tachycardia within the right atrial appendage in a patient presenting with tachycardia - induced cardiomyopathy .