sevoflurane does not sensitise the myocardium to arrhythmogenic effects of catecholamines and has the least effect on cardiac conduction system . despite all the research demonstrating its safety , adverse cardiac arrhythmias such as nodal rhythm with bradycardia , prolongation of qtc interval , precipitation of torsade de pointes and isorhythmic atrioventricular dissociation ( isravd ) have been reported with sevoflurane anaesthesia . a 60-year - old woman weighing 60 kg with carcinoma in the right breast was scheduled for elective modified radical mastectomy . she was a known hypertensive since 4 years , on treatment with oral metoprolol 50 mg twice daily and amlodipine 10 mg once daily , with no other comorbidities . preoperative pulse rate ( pr ) was 60/min and blood pressure ( bp ) was 140/70 mmhg . preoperative 12 lead electrocardiograms ( ecg ) showed sinus rhythm with a rate of 60/min . diazepam 10 mg was administered orally the night before and 60 minutes before surgery , along with morning dose of metoprolol and amlodipine . anaesthesia was induced with 8% sevoflurane in 100% oxygen after administering 1.5 mg morphine intravenously . during induction , sevoflurane concentration was reduced to 5% and satisfactory proseal laryngeal mask airway insertion ( size 3 ) was accomplished with suxamethonium 100 mg . capnograph showed a square wave form . immediately following induction , ecg trace in lead ii showed dissociated upright p waves which remained within qrs for several beats , then reappeared and recede from qrs complex . ecg also showed intermittent electrical alternans [ figure 1 ] and bp dropped to 86/50 mmhg . meanwhile , anaesthesia was maintained with sevoflurane 2% and 50% nitrous oxide in 50% oxygen . end - tidal carbon dioxide ( etco2 ) was maintained between 35 and 37 mmhg . pr ( 40 - 50 beats / min ) and rhythm ( isravd ) remained unaltered throughout the procedure that lasted for 3 hours . atropine 0.6 mg and mephenteramine 3 mg were administered intravenously when the pr dropped below 40/min and systolic bp below 90 mmhg . a discrepancy was observed between the hr recorded by the ecg and pr recorded by the pulse oximeter . hr was 50 to 60 beats / min but pr was 38 to 40 beats / min . at the end of surgery , sevoflurane was discontinued and neuromuscular blockade was reversed with a mixture of atropine ( 1.2 mg ) and neostigmine ( 2.5 mg ) . few minutes after removal of the lma , rhythm reverted to sinus with pr of 50/min and bp was 118/79 mmhg . metoprolol and amlodipine were discontinued and enalapril 5 mg once daily was started by the cardiologist postoperatively . patient was observed in intensive care unit for the next 48 hours . throughout the postoperative course , hr and rhythm remained normal . real - time picture from the monitor shows electrical alternans with absent p waves in ecg trace . the difference in heart rate ( ecg trace ) and pulse rate ( pulse oximetry trace ) is seen due to electrical alternans . real - time picture from the monitor shows the inspired and expired concentration of sevoflurane a 5-year - old boy weighing 15 kg was scheduled for left inguinal hernia repair . premedication administered was 7 mg of oral midazolam , 30 minutes before surgery . in the operating room , baseline pr was 88/min with sinus rhythm ; spo2 , 99% on room air and nibp , 96/62 mmhg . inhalation induction of anaesthesia was performed with sevoflurane in 100% oxygen ( fresh gas flow 5 l / min ) through t piece circuit with child breathing spontaneously at a rate of 20 to 24/min . inspired concentration of sevoflurane was increased in 2% increments every minute up to 8% concentration . the etco2 was between 31 and 33 mmhg , as measured through the angle piece interfaced between the face mask and the breathing circuit . after breathing 8% sevoflurane for 2 minutes sudden drop in hr to 56/min was noticed and the ecg revealed the presence of junctional rhythm with absent p waves and regular narrow qrs complexes . at that moment , spo2 was 99% and bp was 66/36 mmhg . intravenous fentanyl ( 30 g ) was administered and anaesthesia was maintained with 1.5% isoflurane in a mixture of 50% nitrous oxide in oxygen ( fresh gas flow rate 5 l / min ) . a 60-year - old woman weighing 60 kg with carcinoma in the right breast was scheduled for elective modified radical mastectomy . she was a known hypertensive since 4 years , on treatment with oral metoprolol 50 mg twice daily and amlodipine 10 mg once daily , with no other comorbidities . preoperative pulse rate ( pr ) was 60/min and blood pressure ( bp ) was 140/70 mmhg . preoperative 12 lead electrocardiograms ( ecg ) showed sinus rhythm with a rate of 60/min . diazepam 10 mg was administered orally the night before and 60 minutes before surgery , along with morning dose of metoprolol and amlodipine . anaesthesia was induced with 8% sevoflurane in 100% oxygen after administering 1.5 mg morphine intravenously . during induction , sevoflurane concentration was reduced to 5% and satisfactory proseal laryngeal mask airway insertion ( size 3 ) was accomplished with suxamethonium 100 mg . capnograph showed a square wave form . immediately following induction , ecg trace in lead ii showed dissociated upright p waves which remained within qrs for several beats , then reappeared and recede from qrs complex . ecg also showed intermittent electrical alternans [ figure 1 ] and bp dropped to 86/50 mmhg . meanwhile , anaesthesia was maintained with sevoflurane 2% and 50% nitrous oxide in 50% oxygen . end - tidal carbon dioxide ( etco2 ) was maintained between 35 and 37 mmhg . pr ( 40 - 50 beats / min ) and rhythm ( isravd ) remained unaltered throughout the procedure that lasted for 3 hours . atropine 0.6 mg and mephenteramine 3 mg were administered intravenously when the pr dropped below 40/min and systolic bp below 90 mmhg . a discrepancy was observed between the hr recorded by the ecg and pr recorded by the pulse oximeter . hr was 50 to 60 beats / min but pr was 38 to 40 beats / min . at the end of surgery , sevoflurane was discontinued and neuromuscular blockade was reversed with a mixture of atropine ( 1.2 mg ) and neostigmine ( 2.5 mg ) . few minutes after removal of the lma , rhythm reverted to sinus with pr of 50/min and bp was 118/79 mmhg . metoprolol and amlodipine were discontinued and enalapril 5 mg once daily was started by the cardiologist postoperatively . patient was observed in intensive care unit for the next 48 hours . throughout the postoperative course , hr and rhythm remained normal . real - time picture from the monitor shows electrical alternans with absent p waves in ecg trace . the difference in heart rate ( ecg trace ) and pulse rate ( pulse oximetry trace ) is seen due to electrical alternans . a 5-year - old boy weighing 15 kg was scheduled for left inguinal hernia repair . premedication administered was 7 mg of oral midazolam , 30 minutes before surgery . in the operating room , baseline pr was 88/min with sinus rhythm ; spo2 , 99% on room air and nibp , 96/62 mmhg . inhalation induction of anaesthesia was performed with sevoflurane in 100% oxygen ( fresh gas flow 5 l / min ) through t piece circuit with child breathing spontaneously at a rate of 20 to 24/min . inspired concentration of sevoflurane was increased in 2% increments every minute up to 8% concentration . the etco2 was between 31 and 33 mmhg , as measured through the angle piece interfaced between the face mask and the breathing circuit . after breathing 8% sevoflurane for 2 minutes , the child did not show any motor response to jaw thrust . sudden drop in hr to 56/min was noticed and the ecg revealed the presence of junctional rhythm with absent p waves and regular narrow qrs complexes . at that moment , spo2 was 99% and bp was 66/36 mmhg . intravenous fentanyl ( 30 g ) was administered and anaesthesia was maintained with 1.5% isoflurane in a mixture of 50% nitrous oxide in oxygen ( fresh gas flow rate 5 l / min ) . american college of cardiology / american heart association recommends using volatile agents during non - cardiac surgery for the maintenance of general anaesthesia in haemodynamically stable patients at risk for myocardial ischemia . anticipating a difficult airway and considering the patient 's cardiac status , and associated hypertension , isravd was recorded during induction of anaesthesia with sevoflurane which reverted back to sinus rhythm after discontinuation of sevoflurane during emergence . 2 pacemakers ( sinus and av nodes ) fortuitously discharge at the same or nearly similar rate , without antegrade or retrograde conduction across the av node . either slowing of the sinus node discharge rate or the emergence of a slightly faster subsidiary pacemaker controlling the ventricles is the common initiating event . p waves approaches the narrow qrs complex , disappears within it for several beats , then reappears and recedes from the qrs and this sequence may be repeated . the same was observed in the ecg recording in the present case [ figure 1 ] . from the limited number of experimental studies , the development of isravd and the particular electrocardiographic patterns resulting from there are dependent upon relative discharge rate of the dominant atrial and subsidiary pacemakers , presence or absence of retrograde conduction , chronotropic response to atrial stretch , baroreceptor - mediated autonomic nervous system output and responsiveness of the sinus node . high incidence of nodal rhythm ( 20% ) and bradycardia with use of sevoflurane has been reported in unpremedicated infants . the onset of nodal rhythm was significantly earlier in the high - concentration technique than with incremental induction technique . on the other hand , nakaigawa et al . demonstrated that up to 2 mac ( minimal alveolar concentration ) sevoflurane does not affect cardiac conduction system significantly . in both our patients , 8% sevoflurane was used for induction that possibly resulted in isravd and junctional rhythm . isravd was possibly precipitated by the volatile agent affecting ca release from the sarcoplasmic reticulum , resulting in depression of ca slow inward current in the myocardium . in patients on ca channel and -adrenergic blocker therapy , the arrhythmogenic potential of sevoflurane is likely to be enhanced as ca channel blockers inhibit the entry of ca into the cell or its mobilisation from intracellular stores , while b - adrenergic blockers depresses sinus rate and av node conduction . reported a case of intraoperative torsades de pointes ventricular tachycardia and ventricular fibrillation during sevoflurane anaesthesia , which persisted with dc shock but reverted to sinus rhythm after 10 minutes of discontinuation of sevoflurane and after the patient was awakened . a discrepancy was observed between the hr and the pr due to intermittent electrical alternans in the ecg . it is therefore wise to rely on the pr rather than the hr in such cases to treat bradycardia . rarely , sevoflurane - induced suppression of baroreceptor reflex activity might result in desynchronisation between the atria and ventricle causing haemodynamic instability which may require electrical pacing . to conclude , sevoflurane in high concentration ( 8% ) should be used with caution in children and in conditions where primary pacemaker activity is suppressed , as in elderly . caution should also be exercised with its use in patients on ca channel and b blocker therapy .
when inhalational induction is indicated , sevoflurane is the most popular choice in both children and adults . 
 higher inspired concentrations of sevoflurane can cause adverse cardiac arrhythmias that are seen to disappear once the agent is discontinued . 
 we report the occurrence of isorhythmic atrioventricular dissociation and junctional rhythm with absent p waves during sevoflurane anaesthesia in an adult and a child , respectively .