The Early Results of the Growing Activity of Radiofrequency Catheter Ablation of Cardiac Arrhythmias in the Cardiology Department of

Assiut University Hospital 

Salah Atta, MD, Lecturer of Cardiology

Department of Cardiology, Assiut University Hospitals

Egyptian Soceity Congress 2005

EPS and RF ablation in Assiut Cardiology Department.

• Electrophysiologic study and radiofrequency ablation of tachyarrhythmias is one of the essential services needed by the Cardiac patients.

• Here we present the initial local expereince of our team in this field which started 12 months ago in Assiut University Hospitals as the only center to present this service to more than 20 million people living in upper Egypt.

Patients and methods:

• Our initial work includes the successful management of 20 patients (9 males) with a mean age of 40.5 15 years who presented to the Cardiology department of Assiut University Hospitals complaining of recurrent medically refractory sustained tachycardias.

• The duration of the complaint ranged from 2 weeks up to 22 years which was met in a female patient coming from Aswan who was searching for a solution of her problem but unable to come to qualified centers in Cairo till we started our activity in our relatively nearby center.

• All patients had a recurrent narrow complex tachycardia of a rate between 160-220 B./min except three who presented with a wide complex tachycardia (WCT). After ablation, patients were regularly followed up in our arrhythmia and pacemaker outpatient clinic for any recurrence or post ablation complication.

• In addition to the clinical assessment and routine cardiac work up, the patients were subjected to Diagnostic electrophysiologic study (EPS).

• A diagnostic EPS was performed in all the patients to diagnose the mechanism of tachycardia as a step for radiofrequency ablation.

• For pacing and extrastimulating the right atrium and the right ventricle, standard 6 French quadripolar electrode catheters were positioned in the high right atrium and at the right ventricular apex from the left femoral vein, respectively. A third similar catheter was placed to record the His-bundle activation. Coronary sinus mapping was acheived by placing a 6 French 'USCI' octapolar catheter in the coronary sinus through the left subclavian vein. The cases were displayed on a computerized Brucka system, which stored all recordings on laser discs. Reproduction of tracings was on an HP laser printer.

• A 7 french catheter with a large-tip electrode (4 mm long, 27 mm2 surface area) with 2.5 mm interelectrode distance was used for mapping/ radiofrequency ablation of the slow pathway, or the accessory pathway or the Cavo-tricuspid isthmus in case of atrial flutter.

• Sustained tachycardia was induced by programmed atrial and ventricular extrastimulation and the mechanism of tachycardia was classified using the following criteria:

• (A) EPS Diagnostic criteria of AVNRT:

• 1-The initiation of AVNRT was dependent on a critical delay in the AH interval (AH jump).

• 2- The occurence of atrial activation simultaneously with or before the ventricular activation during the SVT (V-A<70msec).

• 3- Retrograde VA during AVNRT was earliest on HBE with a VA interval 70 msec.

• 4- Inability of His synchronous ventricular extrastimuli to pre-excite the atria during AVNRT, 5- Identical sequence of retrograde atrial activation during tachycardia and ventricular pacing. 6- Constant H-A interval of the return cycle after introduction of a premature atrial impulse with a wide range of coupling intervals during tachycardias.

• Manifest pre-excitation:• Shows the following electrophysiologic criteria:• In sinus rhythm, the AH interval is normal while

the HV interval is shorter than 35 msec.• The anterograde curve is non decremental. • During ventricular pacing with extrastimulation,

the retrograde curve is also non decremental. The retrograde atrial activation sequence depends on the site of the accessory pathway and simulates that during orthodromic AVRT.

• - AVRT is induced and terminated by VPD, APDs or pacing. The retrograde atrial activation sequence during AVRT is eccentric (away from V wave) and fixed independent of the SVT cycle length.

• Both the atrium and the ventricle are necessary for initiation and continuation of AVRT. AV or VA block would interrupt the AVRT.

• His synchronous VPDs, during AVRT, either terminates the tachycardia or conducts up the AP pre-exciting (advancing) the atria.

• 2- Concealed pre-excitation (unidirectional retrograde conduction over the AP):

• Has the same electrophysiologic properties of manifest APs in the retrograde direction. Anterogradely, conduction is decremental as the impulses proceed over the AV node.

•  

• The end points of the procedure were the non-inducibility of AVNRT and preferably, loss of duality of the AV node pathways in case of slow pathway ablation, in the case where the anterior approach was neede and fast pathway ablation was done, the end points of the procedure were the acheivement of complete retrograde VA block over the fast pathway during ventricular pacing and the non induciblility of AVNRT or the prolongation of A-H interval by 30%.

• No inducibility of SVT and absence of both retrograde and anterograde conduction of the accessory pathway were the criteria for a successful attempt.

• In all patients, failure of re-induction of the SVT by atrial pacing with atrial extrastimulation, incremental atrial pacing, ventricular pacing with ventricular extrastimulation, incremental ventricular pacing before and after isoprenaline infusion at least 30 min post ablation was the markers of successful ablation.

Results

• The EP study showed that 12 patients had A-V nodal re-entrant tachycardia. They were subjected to successful slow pathway ablation with a range of 1-4 RF applications per patient. One patient with AVNRT required RF application anteriorly in the triangle of Koch as all posterior and mid positions were unsuccessful i.e fast pathway ablation which was done carefully and was uncomplicated.

• Six patients had accessory pathway (AP) dependant tachycardia including pre-excited AF (Life threatening arrhythmia that may degenerate to VF) in two of them. Two patients had manifest right posteroseptal, 2 manifest left lateral and two had a concealed left lateral AP).

• All accessory pathways were successfully ablated with 1-3 RF applications per patient.

• One patient had Long R-P tachycardia that proved to be due slowly retrograde conducting Rt midseptal accessory pathway and was successfuly ablated during the tachycardia.

• The remaining patient had typical atrial flutter with aberrant 2:1 A-V conduction and needed 7 RF applications to achieve bidirectional block in the Cavo-Tricuspid isthmus.

• So we had 100% primary success rate and all procedures were uncomplicated. During a mean follow up period of 7 5 months, one clinical recurrence in a patient with a concealed Left lateral AP was recorded (95% success rate).

Fig.1: Narrow complex tachycardia proved later to be due to AVNRT.

Fig5: ECG during pre-excited atrial fibrillation.

Fig8: Normalisation of the ECG after successful ablation.

V pacing post

Conclusion

• Despite the small numbers, The high primary success rate and low recurrence rate after radiofrequency catheter ablation of SVT in the Cardiology department in Assiut University Hospital are the best call for more and more refferal of patients with cardiac tachyarrhythmia from other centers in Assiut and Upper Egypt to our laboratory.

Conclusion

• The initial promising results of our RF ablation team encourages us to increase our activity and ask for more support to expand our activity to more complicated cases and present this curative treatment of one of the medically resistant cardiac problems to the population of patients in Upper Egypt who are in need it..

 

Thank you