|Year : 2016 | Volume
| Issue : 1 | Page : 37-43
Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of ventricular tachycardia
Kelechukwu Uwanuruochi1, Sabari Saravanan2, Anita Ganasekar3, Benjamin Solomon4, Ravikumar Murugesan4, Ruchit A Shah5, Jaishankar Krishnamoorthy6, Ulhas Pandurangi6
1 Department of Medicine, Federal Medical Centre, Umuahia, Nigeria; Department of Cardiac Electrophysiology, Institute of Cardio-Vascular Diseases, Madras Medical Mission, Chennai, Tamil Nadu, India
2 Electrophysiology and Biomedical Engineering, St. Jude Medical, Chennai, Tamil Nadu, India
3 Department of Cardiac Electrophysiology, Institute of Cardio-Vascular Diseases, Madras Medical Mission, Chennai, Tamil Nadu, India
4 Department of Laboratory Technology, Institute of Cardio-Vascular Diseases, Madras Medical Mission, Chennai, Tamil Nadu, India
5 Department of Medicine, Madras Medical Mission, Chennai, Tamil Nadu, India
6 Department of Cardiology, Institute of Cardio-Vascular Diseases, Madras Medical Mission, Chennai, Tamil Nadu, India
|Date of Web Publication||6-Sep-2016|
Department of Medicine, Federal Medical Centre, Umuahia, PMB 7001, Nigeria
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Cardiac electrophysiologic study (EPS) and radiofrequency (RF) ablation have become an established mode of treatment for patients with refractory arrhythmias. These procedures are carried out regularly at the cardiac catheterization laboratory of Madras Medical Mission India.
Objective: The purpose of this study was to evaluate our experience with cardiac EPSs and Radiofrequency ablations (RFAs) of ventricular tachycardia (VT).
Methods: This was a retrospective study carried out in the Cardiac Electrophysiology Department of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. All cases diagnosed to have VT following cardiac EPS between January 2010 and April 2014 were selected for the study. The records which were obtained from the Cardiac Electrophysiology Clinical Research Office of Madras Medical Mission were reviewed. One hundred and thirteen cases were chosen for the analysis, using SPSS statistical software version 15.
Results: There were 113 patients, comprised 78 males and 35 females. The mean age was 48.79 years. Common etiologic classes of VT were idiopathic outflow tract VT - 50.4%, ischemic heart disease - 20.4%, arrhythmogenic right ventricular cardiomyopathy (ACMP) - 11.5%, and idiopathic dilated cardiomyopathy (IDCM) - 12.4%. Ablation was attempted in 92 (82.1%). The initial outcome was highest in IDCM, 87.5%, and least in ACMP, 50.0%.
Conclusions: Treatment of VT by RFA is comparatively effective and safe.
Keywords: Initial outcome, invasive cardiac electrophysiologic studies, radiofrequency ablation, ventricular tachycardia
|How to cite this article:|
Uwanuruochi K, Saravanan S, Ganasekar A, Solomon B, Murugesan R, Shah RA, Krishnamoorthy J, Pandurangi U. Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of ventricular tachycardia. Ann Nigerian Med 2016;10:37-43
|How to cite this URL:|
Uwanuruochi K, Saravanan S, Ganasekar A, Solomon B, Murugesan R, Shah RA, Krishnamoorthy J, Pandurangi U. Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of ventricular tachycardia. Ann Nigerian Med [serial online] 2016 [cited 2021 Jan 24];10:37-43. Available from: https://www.anmjournal.com/text.asp?2016/10/1/37/189799
| Introduction|| |
Ventricular tachycardia (VT) is an abnormal rapid heart rhythm originating from the ventricles; the ventricles beat at a rapid rate, typically from 120 to 300 beats/min, and are no longer coordinated with the atria.
VT can be classified by morphology (monomorphic or polymorphic), duration (sustained, i.e., lasting >30 s or nonsustained), and underlying mechanisms or underlying “substrate” (e.g., coronary artery disease, mitral valve prolapse, and dilated cardiomyopathy). It is referred to as idiopathic VT in the absence of any identifiable structural heart disease.
Specific types of VT include the following:
- Fascicular tachycardia which originates from the left bundle branch and the QRS complexes have a right bundle branch block pattern
- Right ventricular outflow tract (RVOT) tachycardia, which originates from the RVOT; the electrocardiography typically shows right axis deviation, with a left bundle branch block (LBBB) pattern
- Torsades de pointes, a distinctive polymorphic VT associated with a prolonged QT interval in which the QRS amplitude varies and the QRS complexes appear to twist around the baseline and
- Bundle-branch re-entrant tachycardia which is VT due to re-entry involving the His-Purkinje system, usually with LBBB morphology and usually occurs in the setting of cardiomyopathy.,,
Individuals who have nonsustained VT but have no structural damage to the heart muscle, valves, or other symptoms may not require drug treatment. Underlying metabolic abnormalities or other cardiac disorders that may cause the condition should be addressed. Sustained VT is treated initially with antiarrhythmic drugs. Electric cardioversion may be required. An implantable cardiac defibrillator (ICD) may be implanted surgically followed by administration of antiarrhythmic drugs if the arrhythmia continues despite the ICD. For continued recurrence notwithstanding these measures, radiofrequency catheter ablation may be required.,
RFA for VT in Southeast Asia is underreported , as most systematic studies have come from developed nations. In this report, we reviewed cases of VT in patients treated at the Cardiac Electrophysiology Department of Madras Medical Mission, India, between January 2010 and March 2014, with a view to describing the burden of VT, electrophysiologic characteristics, associations, lines of management, as well as the initial outcome following radiofrequency catheter ablations.
| Materials and Methods|| |
The study was carried out in the Cardiac Electrophysiology Department of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. Ethical approval was obtained from the department. We retrospectively studied the records of cases of VT that underwent cardiac electrophysiologic studies (EPS) carried out from January 2010 to March 2014. VT was diagnosed based on the standard criteria , being characterized by wide QRS (≥120 ms) tachycardia and totally different from the complexes during supraventricular rhythm, dissociation of atrium from the ventricle by overdrive atrial pacing during tachycardia, tachycardia always starting with “V” and tachycardia terminating several times with “A,” presence of intermittent fusion and normal capture beats, absence of HIS bundle potential preceding ventricular activation during the tachycardia, and morphological criteria which include any of the following if there is LBBB pattern: Initial R more than 40 ms, slurred or notched downstroke of S in V1 or V2, beginning of Q to nadir of S >60 ms in V1 or V2, and Q or QS in V6 and any of the following if there is RBBB pattern: Monophasic R, RSr, or qR in V1 and rS or QS in V6.
Patients had been chosen for cardiac electrophysiologic assessment if they had recurrent, drug refractory palpitations, recurrent palpitations with a preference for ablative therapy over pharmacological, recurrent palpitations in association with syncopal attacks or dyspnea, recurrent or incessant VTs, tachycardiomyopathy, and recurrent shocks for patients with automatic implantable cardioverter defibrillator device. Two electrophysiologists carried out the RFA. In our study, we described the demographic characteristics of the patients, indication for the procedure, etiological type of VT, and compared the groups with respect to age, gender, procedure time, recurrence rate of VT, presence of scar tissue, and outcome of RFA. Classification into etiological classes was assisted by other medical data such as medical history and investigations such as coronary and ventricular angiography, echocardiography, magnetic resonance imaging of the heart, and cardiac biopsy. Access was obtained through the right femoral vein and right femoral artery (left femoral vein or left femoral artery were used if the above-named vessels could not be negotiated due to tortuosity). Catheters used were Quadripolar 6F for right ventricular apex (RVA), high right atrium, and HIS; Decapolar 6F for coronary sinus, RVOT, and left ventricle mapping; THR curve STD 7F Cordis Webster, Medium Curve 7F, EPT Blazer II, Cool Flex (St. Jude), and Cool Path (ST Jude IBI) irrigation catheter for the ablator; and St. Jude Ensite Velocity Ensite array multi electrode diagnostic catheter for mapping. VT was induced [Figure 1] and [Figure 2] with programmed right ventricular apical stimulation or with isuprel infusion and vigorous protocols. The VT was terminated with ventricular overdrive from right ventricle or left ventricle, and where it could not terminate the tachycardia, it could be terminated only by DC version. Conventional as well as three-dimensional electroanatomical mapping system [St. Jude Ensite Velocity, [Figure 3] was used to locate the earliest activation site, employing variously in combinations scar, activation, pace, or voltage mapping. Where signals were satisfactory, few RF energies were delivered. Standard cumulative RF energy delivered was 240 s, 60 C, 50 W.
Oral anticoagulation was stopped at 2–3 days before the ablation procedure. Throughout the procedure, the activated clotting time (ACT) was maintained between 250 and 300 s using intravenous heparin. A conscious sedation using intravenous fentanyl and propofol was also maintained throughout the procedure. Antiarrhythmic drug treatment was suspended for the day of the ablation procedure and restarted the following day.
VTs were mapped after performing activation, pace mapping, and scar mapping in both right and left ventricles. In the regions where mapping was satisfactory, few RF energies were delivered using various ablators including Thr curve Std. 7 Fr J and J Cordis Webster, Cool Path/Cool Flex therapy, Thr Curve Std, 7 Fr EPT Blazer II and SAFIRE Ablation. A standard of 240 s, 50°C,50 W was used. The data were analyzed using SPSS statistical software version 15 (SPSS, Inc. Chicago, IL, USA).
| Results|| |
Totally, 113 cases of VT documented following cardiac EPS were reviewed, comprised 78 males and 35 females. The mean age was 48.79 years. The distribution of indications for cardiac electrophysiologic assessment in the patients was recurrent, drug refractory palpitations 44 (38.9%), resuscitated cardiac arrest 13 (11.5%), palpitations with syncope/presyncope 13 (11.5%), presyncope/syncopal attacks 12 (10.6%), recurrent shock from artificial ICD (AICD) therapy 12 (10.6%), recurrent/incessant VT 7 (6.2%), and documented wide QRS tachycardia 10 (8.8%). Syncope with severe left ventricular dysfunction, palpitations/dyspnea/presyncope, and tachycardiomyopathy were the indications in 1 (0.9%) case each.
Over the study period, 968 cases of EPS were carried out, of which 842 underwent RFA. A total of 92 (9.50%) of these RFAs were for patients with VT. In 79 patients (70.5%), use of three-dimensional electroanatomical mapping system was documented. In 25 patients (22.3%), RF energy by conventional catheter was inadequate, and cool path or Cool Flex therapy was used.
The etiological classification is shown in [Table 1].
Artificial implantable cardioverter defibrillators implantation had been implanted for 13 (11.5%) patients as follows: Ischemic heart disease (IHD) 7, idiopathic dilated cardiomyopathy (IDCM) 5, and arrhythmogenic cardiomyopathy (ACMP) 1 while 1 patient with IDCM had a cardiac resynchronization therapy-defibrillator. The study groups are compared in [Table 2].
Following mapping, the sites of origin (and ablation) for the common types of VT were identified as follows. In IHD, in 15 cases, the LV was the site of origin (septal 3, LV freewall 2, basal 3, apical 1, unspecified LV site 6) whereas in two cases, the RV (RV inflow and right posteroseptal areas) was the site of origin. The site was not specified in five cases. In IDCM, eight cases had sites from the LV (septal 1, freewall 2, basal 2, mitral annular 1, unspecified LV 2). The site was unspecified in four while two cases had sites in both ventricles. In ACMP, three patients had unspecified RV sites while others are RVOT 1, para-Hisian 1, RV inflow 1, RV between inflow and outflow 1, RV apical 1, left posterior fascicle 1. In two cases, the site was not specified while one had VT arising from sites in both ventricles. Most idiopathic outflow tract VT (IOTVT) arose from the RVOT, 27. There were 19 from LV posterior fascicular VT, 5 LVOT, 3 LV anterior fascicular VT, 1 left posteroseptal, and 1 mitral annular while the site was not specified site in 1.
RFA was carried out in 92 patients (82.1%). The success rate could be determined in 78, being successful in 58 patients (74.4%) and unsuccessful in 20 (25.6%). The outcome in the common types is described in [Table 3]. It was highest in IDCM and least in ACMP. The difference was statistically significant (χ2 = 18.663, P = 0.005).
Factors responsible for inconclusive outcome include such circumstances as noninducibility of sustained tachycardia before ablation, avoidance of induction post-RFA due to degeneration into VF, VT with hemodynamic instability and presence of ischemic cardiomyopathy, etc., and suspension of ablation due to development of ventricular fibrillation (1), suspected catecholaminergic polymorphic VT (1), suspected ACMP (3), deferment for RFA with three-dimensional electroanatomical mapping (4), noninducibility of VT in the EP laboratory (4), and need for AICD implantation (9).
For the common categories, the number of cases in which outcome of RFA was conclusive are as follows: IHD (11), IDCM (8), ACMP (8), and IOTVT (50). Successful outcome was recorded as follows: IHD 8 (72.7%), IDCM 7 (87.5%), ACMP 4 (50.0%), and IOTVT 38 (76.0%). Cases of recurrent VT were recorded in these common categories as follows: IHD 2 (8.69%), IDCM 1 (7.14%), ACMP 2 (15.38%), and IOTVT 2 (3.57%). The trend in outcome over the years is described as in [Table 3].
The early complications noted were all in patients who had outflow tract VT. Five patients had major complications, cardiac tamponade in 4, and complete heart block in 1 while 1 patient also had a fascicular block. DC cardioversion for sustained VT with hemodynamic compromise, incessant VT or VF, was required in 23 (20.35%) patients, IHD in 12, IDCM in 5, ACMP in 4, and IOTVT in 2.
There was no mortality in this review.
| Discussion|| |
This study describes the results of cardiac EPS and catheter ablation of cases of VT carried out in the Electrophysiology Department of Madras Medical Mission between January 2010 and March 2014.
The sex distribution was predominantly male in all types of VT, with the predominance greatest in IHD. The mean age was also highest in VT on the background of IHD. This is expected because age is a known risk factor for IHD. In comparison, Morady et al. found male sex predominance in patients with VT and IHD, and they have reported 13 men and two women. The mean age of their sample was 68 years, even higher than the mean age of 64 years in our IHD patients with VT.
A majority of cases of VT in this study were attributable to IOTVT. This appears contradictory to other reports. Armburst and Levine  found most cases of paroxysmal VT to be due to IHD (79) while only 13 of the 107 patients had no structural heart disease. A number of other studies have also identified IHD as the most common cause.
That most of the cases of VT ablated here were idiopathic in origin seems to suggest that etiology of VT in Southeast Asia differs from observations in the western world. However, a study in Pakistan  showed myocardial ischemia in 43.5%, cardiomyopathy in 23.2% while miscellaneous causes made up the remaining 33.3%. RFA is the treatment of choice in the management of symptomatic patients with VT in the absence of structural heart disease while implantable ICDs have become the treatment of choice for all but incessant VT. The role of RFA in patients with VT in the setting of chronic IHD is thus less well defined. All these would tilt patient selection in favor of those with idiopathic VT and account for its preponderance in the majority of patients studied here.
The success rate appears to be highest for IDCM. However, this is only apparent as the outcome could not be assessed in 42.9%. The outcome could also not be assessed in the majority of the patients with IHD, and in 38.4% of the cases with ACMP. With this in mind, the initial outcome is actually most favorable in IOTVT (where an inconclusive outcome was present in only 12.5%). Higher success rates ranging from 85% to 97% have been reported for cases of idiopathic VT.
The apparently lower success rate in this study would also be balanced against the lower rate of major complications. No major complication was recorded in the categories of IHD, IDCM, and ACMP while the rate in cases of IOTVT was 8.9%. Cardiac tamponade occurred in 4 of the 56 cases with IOTVT. Perforation of the RV freewall has been a recognized complication of IOTVT. Recurrence rate over the duration of the study was also low: 8.7% for IHD, 7.1% for IDCMP, 15.4 for ACMP, and 3.6 for IOTVT. Rates ranging from 19% to 50% have been reported for IHD.
The percentage successful outcome improved from 36.8% in 2010 to 71.4% in 2014. The procedures were described over a time frame of about 4 years. Over the period, there was increased use of three-dimensional electroanatomical mapping system, improvement in patient selection as well as expertise of the electrophysiologists. This reflects the impact of the learning curve on the outcome.
The frequency of granulomatous infiltrations (tuberculosis and sarcoidosis) presenting as VT and optimally managed only with a combination of disease-specific therapies with antiarrhythmics has been reported by Thachil et al. from Hyderabad, India. The prevalence of some granulomatous infiltrations is expected to be higher in the Indian subcontinent and may account for nonresponse in some cases. Computed chest tomography with histological studies of enlarged mediastinal nodes is necessary for detection of this subset. This was not undertaken in this study. This study had other limitations. The nationality of patients was not included in the data collected and the study was retrospective, gaps in the data recorded could not be filled. Important characteristics including family history of arrhythmias and sudden deaths, blood pressures, body mass index, electrolytes, renal function indices, details of pharmacological treatments, and serum lipid profile were also not part of the data retrieved during data acquisition. Follow-up data were also not collected to determine the intermediate-term success rate. It is, however, noteworthy that this is the first systematic report, to the best of our knowledge, of relatively large number of cases of VT following RFA in our center. The reported distribution in types of VT, the success, and complication rates of various types of VT following ablation in our center are thus new contributions to the medical literature.
| Conclusions|| |
This study shows that RF ablation of VT had a high success rate and very low incidence of complications.
We would like to thank the support rendered by the Medical Director of Federal Medical Centre Umuahia, Dr. Abali Chuku, and the Staff of the Electrophysiology clinical research office of Madras Medical Mission.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]