Myocardial ischemia, as well as the induction agents used in anesthesia, may cause corrected QT interval (QTc) prolongation. The objective of this randomized, double-blind trial was to determine the effects of high- vs conventional-dose bolus rocuronium on QTc duration and the incidence of dysrhythmias following anesthesia induction and intubation. Fifty patients about to undergo coronary artery surgery were randomly allocated to receive conventional-dose (0.6 mg/kg, group C, n=25) or high-dose (1.2 mg/kg, group H, n=25) rocuronium after induction with etomidate and fentanyl. QTc, heart rate, and mean arterial pressure were recorded before induction (T0), after induction (T1), after rocuronium (just before laryngoscopy; T2), 2 min after intubation (T3), and 5 min after intubation (T4). The occurrence of dysrhythmias was recorded. In both groups, QTc was significantly longer at T3 than at baseline [475 vs 429 ms in group C (P=0.001), and 459 vs 434 ms in group H (P=0.005)]. The incidence of dysrhythmias in group C (28%) and in group H (24%) was similar. The QTc after high-dose rocuronium was not significantly longer than after conventional-dose rocuronium in patients about to undergo coronary artery surgery who were induced with etomidate and fentanyl. In both groups, compared with baseline, QTc was most prolonged at 2 min after intubation, suggesting that QTc prolongation may be due to the nociceptive stimulus of intubation.

Objective: Existing myocardial damage in coronary artery disease patients causes prolonged QT syndrome. The primary objective of this trial is to explore the effects of different doses of the muscle relaxant agent rocuronium (0.6 mg kg -1 and 1.2 mg kg -1) on QTc following anaesthetic induction. The second objective is to determine the incidence and kinds of arrhythmias. Methods:In this prospective and randomized trial, patients undergoing elective coronary artery revascularization surgery were included in one of two groups. Both groups took the same anaesthetic induction agents: midazolam and fentanyl. Rocuronium was administered in Group 1 (n=20) with dose of 0.6 mg kg -1 and in Group 2 (n=20) with a dose of 1.2 mg kg -1 for muscle relaxation. Heart rate, average arterial pressure and QTc were recorded before induction (T0), after induction (T1), after muscle relaxant (T2), and 2 minutes (T3) and 5 minutes after intubation (T4).Results: QTc was significantly longer 2 minutes after intubation (in Group 1 and Group 2, respectively, 447.9±28.3 and 466.1±37.8 ms) than at the beginning (respectively, 426.9±25.7, 432.0±35.5 ms) (p<0.01). In the intergroup comparison, average QTc values were similar in all trial periods (p>0.05). The prevalence of arrhythmias in between Group 1 (35%, n=7) and Group 2 (15%, n=3) was similar (p=0.06). Arrhythmias were recorded 2 minutes after intubation in both groups (n=10, 25%). Conclusion:In patients undergoing coronary artery revascularization surgery, rocuronium doses of 0.6 mg kg -1 and 1.2 mg kg -1 prolong the QTc interval after intubation. Cardiac arrhythmias related to long QTc arising after intubation should be taken into consideration.Key Words: Rocuronium, QTc, coronary artery disease Amaç: Koroner arter hastalarında, mevcut miyokard hasarının kendisi uzun QT sendromu oluşumuna neden olmaktadır. Ça-lışmanın esas amacı anestezi indüksiyonu sonrasında, roküronyu-mun 2 farklı dozunun (0,6 mg kg -1 ve 1,2 mg kg -1 ) QTc intervali üzerine etkilerini araştırmaktır. ikincil amacı ise aritmi sıklığı ve niteliğini saptamaktır.Yöntemler: Çalışmaya elektif koroner arter revaskülarizasyon cerrahisi geçirecek 40 olgu alındı. Olgular iki gruptan birine dahil edildiler. Gruplarda kullanılan midazolam ve fentanil' in indük-siyon dozları aynı idi. Group 1; 0,6 mg kg -1 , Group 2; 1,2 mg kg -1 doz roküronyum ile entübe edildiler. Kalp atım hızı, ortalama arter basıncı ve QTc, indüksiyon öncesi (T0), indüksiyon sonrası (T1), roküronyum sonrası (T2), entübasyon sonrası 2. dakika (T3) 5. dakikalarda (T4) kaydedildi. Bulgular:Grup içi karşılaştırmada, yalnızca entübasyon sonrası 2. dakikadaki ortalama QTc değerleri (Grup 1 ve Grup 2'de sı-rası ile, 447,9±28,3, 466,1±37,8 ms), başlangıca göre (sırası ile, 426,9±25,7, 432,0±35,5 ms) istatistiksel olarak anlamlı uzun bulundu (p<0,01). Gruplar arası karşılaştırmada, ortalama QTc tüm çalışma dönemlerinde benzerdi (p>0,05). Grup 1 (%35, n=7), ile Grup 2'de (%15, n=3) aritmi görülme sıklığı benzerdi (p=0,06). Her iki grupta da aritmiler (n=10, %25), en...

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