there are no p waves and the rhythm is irregularly irregular , with a variable ventricular rate between 110 and 160 bpm .
the qrs complexes are usually < 120 ms unless there are preexisting bundle branch block , accessory pathway , or rate - related aberrant conduction .
fibrillatory waves , small , irregular waves seen as a rapid - cycle baseline fluctuation , may be seen .
af can be distinguished from atrial flutter ( afl ) by the presence of both saw - tooth wave configuration and slower atrial rates and from atrial tachycardia ( at ) with variable atrioventricular ( av ) block , which usually presents with an atrial rate of approximately 150 beats / min because the atrial rate in at is regular though the conduction to the ventricles is not .
paroxysmal af is self - terminating with episodes lasting < 7 days , persistent af is nonself terminating and last more than 7 days , and permanent af last for more than 1 year .
many possible mechanisms are implicated in the pathophysiology , but it is thought to arise as a result of ectopic activity from tissues surrounding pulmonary veins ( pvs ) and other specialized tissues .
they may occur at any age although it has been more in males , and the elderly and adults with valvular heart disease , especially with mitral valve ( mv ) lesions .
standard treatment methods include the control of ventricular rate , the control of rhythm with antiarrhythmic and prevention of thromboembolism .
surgery can also be used as a method of ablation , radiofrequency ablation ( rfa ) has however become accepted as the treatment of choice for drug - refractory cases , comprising mainly of ablations of peripulmonary areas as well as ablation of the av node ( avn ) with subsequent insertion of a permanent pacemaker .
rfa for af in south - east asia is under - reported , as most systematic have come from developed nations . in this report
, we reviewed cases of af in patients treated at the cardiac electrophysiology department of madras medical mission , india , between the years january 2010 and march 2014 , with view to describing the burden of af , electrophysiologic characteristics , associations , lines of management , as well as the initial outcome following radiofrequency catheter ablations ( rfa ) .
the study was carried out at the cardiac electrophysiology department of the institute of cardiovascular diseases , madras medical mission , india .
we retrospectively studied records of cases of af that underwent cardiac electrophysiologic studies ( eps ) carried out from january 2000 to march 2014 .
af was diagnosed based on standard criteria . in our study , we described the demographic characteristics of the patients , the indication for the procedure and the prevalence of associated cardiovascular morbidity in the patients .
we also observed the percentage of cases with recurrent af following previous rfa and documented the frequency of the various early complications of rfa and the success rate of the procedure .
patients had been chosen for cardiac electrophysiologic assessment if they had recurrent , drug refractory palpitations , recurrent palpitations with preference for ablative therapy over pharmacological , recurrent palpitations in association with syncopal attacks or dyspnea , symptomatic bradycardia , tachycardiomyopathy , and recurrent shocks for patients with automatic implantable cardioverter defibrillator device .
patients with significant basal bradycardia and av nodal disease were not considered suitable for rate limiting drugs and were considered for pv isolation ( pvi ) with or without permanent pacemaker implantation ( ppi ) .
catheters used were quadripolar 6f for high right atrium , his and right ventricular apex , lasso 20 pole 7f or lasso spiral 7f for left atrial mapping , 20 pole optima spiral 6f , reflex on 20 pole and ibi lasso 20 and 10 pole for pv mapping , decapolar 6f for coronary sinus and ept blazer ii 7f std curve , j and j cordis webster medium curve 7f , cool flex ( st .
transeptal punctures was obtained for deploying 8f sheath for ablation , and preface ( johnson and johnson ) sheath for placement of optima 20 pole catheters .
the tachycardia was induced on programed atrial stimulation or with isupril infusion and vigorous protocols . in 21 patients ( 42.9% ) , three - dimensional ( 3d ) electroanatomical mapping system ( st .
jude ensite velocity ) was employed creating a fusion with offline acquired computed tomography images to define the left atrium and pvs .
oral anticoagulation was stopped at 23 days before the ablation procedure . throughout the procedure , the activated clotting time was maintained between 250 and 300 s using intravenous heparin .
antiarrhythmic drug treatment was suspended for the day of the ablation procedure and restarted the following day . for cases where avn ablation was indicated ,
radiofrequency ( rf ) energy were delivered at a site where the compact avn signals were optimal ( a : h : v = 1:2:3 ) to produce complete heart block ( chb ) .
the patient was observed for more than  h to ensure chb persisted . in patients with previous pacemaker implantation ,
the pacemaker was reprogramed to voo , avn was mapped at a site where h : v was 1:4 before rf energy ( 50c , 50 w ) was used to create chb . at the end of 45 min post - rfa
if patient remained in chb , device was reprogramed to vvi mode . where tricuspid valve ( tv ) 
inferior vena cava ( ivc ) isthmus linear lesion was performed , a standard of 480 s , 50c , 50 w was used . for circumferential pv ablations ( pva ) , after identifying the pv potentials , ablation lesions were delivered during sinus rhythm around the left and right superior and inferior pvs , resulting in termination of af followed by the absence of electrical potentials within the pv postablation a power of 30 w and a temperature of 45c was achieved using 7f st .
electrical disconnections into pv were confirmed with spiral catheter recordings documenting the absence of electrical potentials within the pv postablation . in 11 patients ( 22.4% ) ,
rf energy by conventional catheter was inadequate , and cool path irrigation tip catheter was used . where patient remained in af post - rfa , under deep sedation and after confirming the absence of intracardiac clots and after giving intravenous amiodarone 150 mg bolus followed by 50 mg infusion , a single synchronized cardioversion ( 150 j , biphasic ) was delivered using r2 pads to convert to stable sinus rhythm .
for cases where avn ablation was indicated , radiofrequency ( rf ) energy were delivered at a site where the compact avn signals were optimal ( a : h : v = 1:2:3 ) to produce complete heart block ( chb ) .
the patient was observed for more than  h to ensure chb persisted . in patients with previous pacemaker implantation ,
the pacemaker was reprogramed to voo , avn was mapped at a site where h : v was 1:4 before rf energy ( 50c , 50 w ) was used to create chb . at the end of 45 min post - rfa
inferior vena cava ( ivc ) isthmus linear lesion was performed , a standard of 480 s , 50c , 50 w was used . for circumferential pv ablations ( pva ) , after identifying the pv potentials , ablation lesions were delivered during sinus rhythm around the left and right superior and inferior pvs , resulting in termination of af followed by the absence of electrical potentials within the pv postablation a power of 30 w and a temperature of 45c was achieved using 7f st .
electrical disconnections into pv were confirmed with spiral catheter recordings documenting the absence of electrical potentials within the pv postablation . in 11 patients ( 22.4% ) ,
rf energy by conventional catheter was inadequate , and cool path irrigation tip catheter was used .
where patient remained in af post - rfa , under deep sedation and after confirming the absence of intracardiac clots and after giving intravenous amiodarone 150 mg bolus followed by 50 mg infusion , a single synchronized cardioversion ( 150 j , biphasic ) was delivered using r2 pads to convert to stable sinus rhythm .
the data were analyzed using spss statistical software version 15 ( spss , inc . , chicago , illinois , usa ) .
forty - nine cases of af documented following cardiac eps were reviewed , comprised 23 males and 26 females .
the frequency of associated cardiovascular diseases in the patients studied are diabetes mellitus 8 ( 16.3% ) , hypertension 18 ( 36.7% ) , coronary heart disease 14 ( 28.5% ) , hypertrophic cardiomyopathy 1 ( 2.0% ) , tachycardia - induced cardiomyopathy 1 ( 2.0% ) , mv prolapsed 1 ( 2.0% ) , dilated cardiomyopathy 1 ( 2.0% ) , degenerative aortic valve disease 1 ( 2.0% ) , atrial septal defect 1 ( 2.0% ) , congenital bicuspid aortic valve 1 ( 2.0% ) , rheumatic heart disease 1 ( 2.0% ) , myxomatous mv 1 ( 2.0% ) , and hypothyroidism 1 ( 2.0% ) . over the study period ,
a total of 28 ( 3.3% ) of these rfa were for patients with af .
the distribution of indications for cardiac electrophysiologic assessment in the patients were recurrent , drug refractory palpitations 16 ( 32.6% ) , drug - refractory paroxysmal af 7 ( 14.3% ) , sick - sinus syndrome ( sss ) 3 ( 6.1% ) , persistent af 3 ( 6.1% ) , palpitations with syncope / presyncope 5 ( 10.2% ) , resuscitated cardiac arrest 1 ( 2.0% ) , syncopal attacks 3 ( 6.1% ) , af with fvr 4 ( 8.2% ) , palpitations with dyspnea 4 ( 8.2% ) , tachy - brady sss 2 ( 4.1% ) , and suspected sss with avb 1 ( 2.0% ) .
there were three cases of previous rfa , one for typical avn reentry tachycardia ( avnrt ) , and two for af .
documented arrhythmias at baseline are as follows : af 22 ( 44.9% ) , at / afl / af / sinus pauses 5 ( 10.2% ) , afl / af 3 ( 6.1% ) , regular narrow qrs tachycardia in 4 ( 8.2% ) , regular narrow qrs tachycardia with af 3 ( 6.1% ) , regular wide qrs tachycardia 2 ( 4.1% ) , irregular narrow qrs tachycardia 2 ( 4.1% ) , at / af 2 ( 4.1% ) , irregular narrow 2 ( 4.1% ) , combinations of regular and irregular narrow qrs tachycardia 1 ( 2.0% ) , afl / sinus bradycardia 1 ( 2.0% ) , af / atrial ectopics / sinus bradycardia1 ( 2.0% ) , and afl / af / pvc 1 ( 2.0% ) .
the basic electrophysiologic characteristics of the study group are shown in table 1 with sample surface and intracardiac electrograms in figures 1 and 2 .
basic electrophysiologic characteristics of the study group variable p waves and ventricular rate in surface electrocardiogram irregular potentials from the high right atrium in atrial fibrillation echocardiographic findings were documented in 36 ( 73.5% ) of patients .
these include dilated left atrium 6 ( 16.7% ) , global hypokinesia 4 ( 11.1% ) , concentric left ventricular ( lv ) hypertrophy 3 ( 8.3% ) , and mild lv dysfunction 2 ( 5.6% ) .
asymmetrical septal hypertrophy , left atrial clot with global hypokinesia , severe lv dysfunction , atrial septal defect , and moderate lv dysfunction were all present at frequency of 1 ( 2.8% ) while 17 patients ( 47.2% ) had a normal echo study .
it was rapid ( above 100/min ) in 31 ( 91.2% ) , controlled on medication in 2 ( 5.9% ) , and normal in 1 ( 2.9% ) .
fourteen ( 58.3% ) of these did not have any sustained inducible tachycardia , 9 ( 37.5% ) had inducible af while af was persistent in 1 ( 4.2% ) without induction .
the ventriculoatrial activation pattern was documented in 22 ( 43.1% ) , being concentric decremental in 13 ( 59.1% ) , and absent in 9 ( 40.9% ) .
af was paroxysmal in 40 ( 81.6% ) , persistent in 5 ( 10.2% ) , chronic in 3 ( 6.1% ) , whereas a diagnosis of lone af was made in 1 ( 2.0% ) .
the frequency of associated arrhythmias is as follows : tachy - brady sss 6 ( 12.2% ) , at 5 ( 10.2% ) , afl 3 ( 6.1% ) , sss 3 ( 6.1% ) , and ventricular tachycardia ( vt ) 2 ( 4.1% ) while there was one patient ( 2.0% ) for each of the following : typical avnrt , sss / at , at / afl , typical avnrt / at , and atrioventricular nodal disease .
twelve ( 24.5% ) had avn ablation , 10 ( 20.4% ) had circumferential pva [ figure 3 ] .
isthmus lesions were applied in 3 ( 6.1% ) , 2 ( 4.1% ) had ablations of the focus of the initiating at .
avn ablation with isthmus lesions , as well as pva with isthmus lesions was both applied in 1 ( 2.0% ) .
avn ablation with ppi was done in 2 ( 2.7% ) cases , one with associated af with fast ventricular rate , the other a case of tachycardia - bradycardia sss .
circumferential ablation of pulmonary veins rfa was not applied in 21 ( 42.9% ) patients , reasons including : associated vt , considered for rfa of vt with 3d electroanatomical mapping and artificial implantable cardioverter - defibrillator implantation ( 1 ) , deferment for pvi with 3d electroanatomical mapping ( 1 ) , deferment for avn ablation with ppi at a later time ( 2 ) , no intervention planned because af was not sustained ( 1 ) , normal ep study and considered for hutt test ( 1 ) , plan to optimize medications , to consider rfa if af persisted ( 3 ) , medical therapy was recommended ( 6 ) , recommendation for continued monitoring and later review ( 5 ) , recommendation for pvi and ppi ( 1 ) .
af with fvr developed in one patient who had a previous ppi for past indication of symptomatic afl with fast ventricular rate and intermittent prolonged chb .
the pacemaker ( axios s  biotronik ) was first reprogramed to voo and after mapping the avn , rfa was used to created chb , after which the device was reprogramed to vvi mode at a rate of 40/min .
of the 28 patients who had rfa , 11 ( 40.7% ) had his bundle ablation on account of associated fast ventricular rate , 10 ( 20.4% ) had ablations around the pvs ( 5 all pv ostia , 4 left common trunk , and right upper and lower pulmonary ostia , and 1 left superior and inferior pvs ) , 3 ( 6.0% ) had ablations involving the tv 
ivc isthmus / coronary sinus - ivc isthmus on account of associated afl , 3 had ablations of ectopic atrial sites : superior crista region ( 1 ) , para - hisian ( 1 ) and left right atrial free ( 1 ) sites for associated inciting at and one had ablation around the following : left superior pv , left atrial appendage , mitral isthmus , and tv - ivc isthmus .
the patient was direct current - cardioverted and placed on medical therapy pending later review .
in one patient ( 9.1% ) , it was only modified with resulting intermittent chb and complete right bundle branch block post - rfa .
for the three that had inciting at , rfa was successful in 1 , unsuccessful in 1 , and empirical in another .
of the 21 ( 42.9% ) patients not treated with rfa , 8 ( 38.1% ) had normal eps , 4 ( 19.0% ) needed to optimize medication before considering rfa , and 2 ( 9.5% ) needed preparation for ppi .
the following indications were all obtained in only 1 ( 4.8% ) patient : asymptomatic , though persistent af , multiple atrial trigger sites in elderly with dilated left atrium , significant bradycardia in combination with av disease , chronic af , need for 3d electroanatomical study for pvi , underlying hypertrophic cardiomyopathy , and underlying dilated cardiomyopathy .
cardioactive medications recorded in our patients include warfarin 15 ( 30.6% ) , pradaxa 1 ( 2.0% ) , antiplatelets 11 ( 22.4% ) , statins 7 ( 14.35 ) , diltiazem 9 ( 18.4% ) , amiodarone 13 ( 26.5% ) , digoxin 5 ( 10.2% ) , beta - blockers 13 ( 26.5% ) , flecainide 1 ( 2.0% ) , and angiotensin - receptor blockers 6 ( 12.2% ) .
pulmonary edema with accelerated hypertension and sinus tachycardia had developed in the observational period postprocedure , with respiratory acidosis , hypoxia , and hypotension postintubation , requiring elective intubation and inotropic supports . no mortality was seen .
this study describes the results of cardiac electropysiologic study and catheter ablation of cases of af carried out in the electrophysiology department of madras medical mission between january 2000 and march 2014 .
the mean age of 57.3 years in our sample is higher than the figure of 48 years reported by nasser et al . and the 53 years reported by oussama et al .
this may be explained by late referrals in a center from a less developed nation .
the most frequently associated cardiac condition was hypertension , followed distantly by coronary heart disease and diabetes .
reporting from iran found a much lower prevalence of hypertension though it was still the most common associated disease .
however , nielsen et al . reporting from denmark , found a markedly higher association with hypertension , similar to our own study .
it is noteworthy that 3.3% of total ablations in madras medical mission over the study period were for cases of af . in comparison 1.25% of ablations reported by awan et al . from pakistan
were for af and 1.7% was reported by iturralde - torres et al . from mexico .
madras medical mission being a quaternary - level referral center for interventional cardiology in india , a higher hospital prevalence for conditions requiring complex cardiac interventions would be expected .
most cases of af ( 81.6% ) were diagnosed as paroxysmal . majority ( 89.5% ) of the cases reported by williamson et al . were chronic . their study was published in 1994 . as eps becomes more available and affordable , less severe cases are referred for investigation .
a much lower success rate , 4560% , was recorded by chevalier et al . , but this was in the first 100 cases at their center .
a total of 81 ( 95% ) of 85 pvs could be completely isolated in a single - balloon technique by klein et al .
the complication rate was 2.04% , and there was no mortality in this study . in their worldwide survey ,
the rates in our series are therefore comparable to that obtained in other reputable centers worldwide .
it is noteworthy that this is the first systematic report , to the best of our knowledge , of relatively large number of cases of af our center . the reported distribution in types of af , the burden of af , the success and complication rates of af ablation from our center are thus new contributions to the medical literature .
the nationality of patients was not included in the data collected and , the study being 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 , echocardiographic function indices , 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 was also not collected to determine the intermediate - term success rate .
this study shows that rfa of af had a high success rate and very low incidence of complication .
 background : cardiac electrophysiologic study and radiofrequency ablation ( rfa ) 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 electrophysiologic studies ( eps ) and rfa catheter of atrial fibrillation ( af).materials and 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 af following cardiac eps between january 2010 and april 2014 was selected for the study . 
 the records , which were obtained from the cardiac electrophysiology clinical research office of madras medical mission , were reviewed . 
 forty - nine cases were chosen for analysis , using spss statistical software version 15.results:there were 49 patients , 23 males and 26 females . 
 the mean age was 57.53 years . 
 commonly associated diseases were diabetes mellitus 8 ( 16.3% ) , hypertension 18 ( 36.7% ) , and coronary heart disease 14 ( 28.5% ) . 
 the ventricular rate was rapid most cases ( 91.2% ) . 
 af was diagnosed as being paroxysmal in 40 ( 81.6% ) , persistent in 5 ( 10.2% ) , chronic in 3 ( 6.1% ) , and lone in 1 ( 2.0% ) . 
 ablation was carried out in 28 ( 57.1% ) , the success rate being 90% for pulmonary vein isolation , and 90.9% for atrioventricular node ablation . 
 complication rate was 2.04%.conclusions : treatment of af by rfa is highly effective and safe . 