The effect of anaesthesia induction in QT interval at coronary artery disease

Objective: Various medication which are used in anesthesia practices were indicated to interact with QT interval. During anesthesia practices life threatening arrythmias and mortality cases were indicated to be associated with prolonged QT interval. The primary objective of this trial is to show the effects of midazolam+fentanil or hipnomidat+fentanil and two different doses of muscle relaxant agent rokuronyum (0.6 mg.kg-1 and 1.2 mg.kg -1) on QTc interval which are usually used in anesthesia induction.Appliance and Method: Trial was applied prospectively in Celal Bayar University Medical Faculty Cardiothoracic Surgery Operating Room between 04.2010-12.2010 upon receiving 0057 numbered approval from Celal Bayar University Medical Faculty Dean?s Office Ethics Committee. 44 cases who will undergo Elective Coronary Arteria Revascularisation Surgery. Exclusion criteria was determined as requisition of resuscitation and destroy of hemodynamic stability during anesthesis induction.When the patients were introduced into operating room, to record heartbeat graphy continuously, 7 ported Holter device (DM Software, NV, USA) electrodes were place on front face of thorax and contunious record was started. Record was ended in 5th minute after entubation.Before anesthesia induction cases were included in one of four groups by lottery. By hypnotic aim, in Group 1 and 2 midazolam was administered with dose of 0.06- 0.1 mg.kg-1 , in Group 3 and 4 etomidat with dose of 1,2 mg.kg-1 with intravenous way by titration. Fentanil 3-4 µg.kg-1 was administered in all groups. Rokuronyum was administered in Group 1 and 3 with dose of 0.6 mg. kg-1 and in Group 2 and 4 with dose of 1.2 mg.kg-1 for muscle relaxation.Heartbeat rate and avarage arteria pressure data were recorded in the beginning before induction (T0), after induction (from administration of induction medication until eyelash reflex disappears) (T1), after muscle relaxant (from administration of muscle relaxant agent until TOF < %5) (T2), 2nd minute after entubation (T3) and 5th minute after entubation (T4). Same time ranges were marked on Holter device by pressing marking buton (EVENT) contuniously during record. After trial ends, Holter records were evaluated by a cardiologist; blined to trial groups. In every time ranged marked during record, 2 RR ranges which was random chosen in 1 minut periods and QT period averages were recorded. QTc calculation was performed by Bazette calculation. The values after 440 seconds were evaluated as long QTc.Findings: When compared to beginning, QTc did not change after administration of induction medication and rokuronyum in all groups (p>0.05), significant prolongation was observed in 2nd minute after entubation (p<0.05). In intergroup comparison, avarage QTc values were similar in all trial periods (p>0.05).Between Group 1(% 33, n:5, % ) and Group 2 (% 33, n:5) and between Group 3 (% 0, n:0) and Group 4 (% 0, n:0) arrythmia frequency was similar (p>0.05). Betwen Group 1 and Group 3 and between Group 2 and Group 4, arrythmia freqeuncy did not show statistically significant difference (p>0.05). In Group 2, premature atrial contraction existed in 2 cases in the beginning. This arrythmia proceed during all trial period. In 2 cases in Group 2 ST depression was observed in 2nd minute after entubation. All other arrythmias (n:8,%80 of cases that arrythmia was observed after entubation) existed during laryngoscopy and in 2nd minute after entubation and contunied in 5th minute. In 1 case in Group1 non sustained ventricular taschycardy existed.Arrythmia was observed in 3 cases (%7.1) who had long QTc (%72,7, n:32) after entubation. In 7 cases (%58.3) who did not have long QTC (%27,3, n: 12 ), arrythmia existed. Statistical significancy was not observed between arrythmia and long QTc (p>0.05). Arryhtmias did not cause hemodynamic worsening and did not require theraphy.Consequently, in induction of coronary arteria revascularisation applicable patients, both 1.2 mg. kg -1, 0.6 mg. kg -1 doses of etomidat+fentanil and midazolam+fentanil and rokuronyum were concluded as securely usable without causing prolongation in QTc interval. Laryngoscopy and entubation caused prolongation in QTc interval and arrythmia. Administration of Beta Blocked did not prevent prolongation of QTc and arrythmia existence caused by entubation. Case shortage in this trial restricts trial results. We are in opinion of extending this trial by increase in number of cases.