Anaesthetics and the rate corrected interval: learning from droperidol?

Shipton, Edward A.

doi:10.1097/01.aco.0000168329.10067.1a

Cited by 6 publications

(4 citation statements)

References 32 publications

(121 reference statements)

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“…In Group T we observed significant heart rate lowering (expressed as prolongation of the RR interval) without a parallel change in uncorrected QT time, which may explain why significant changes were seen only for QT cb , whereas QT cf and QT cF remained unchanged. In addition, parallel reductions in TDR induced by thoracic epidural anaesthesia were observed and this may augment our hypothesis about the anti‐arrhythmic properties of thoracic epidural anaesthesia, in particular that there is a strong correlation between changes in TDR and torsadogenic drug action 16,21 …”

Section: Discussionsupporting

confidence: 71%

“…Although prolongation of the QT c interval is known to be a risk factor for ventricular arrhythmias, it is not the sole determinant of an agent's potential to cause TdP. It is believed that a parallel increase in the TDR in particular predisposes patients to torsadogenic drug action 16 . Sympathetic blockade of the heart resulted in a reduction in TDR.…”

Section: Discussionmentioning

confidence: 99%

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Effects of Thoracic Epidural Anaesthesia on Cardiac Repolarization

Owczuk¹,

Steffek²,

Wujtewicz³

et al. 2009

Clin Exp Pharma Physio

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1. Prolongation of the QT interval is associated with a risk of life-threatening cardiac arrhythmias. In the present study, we examined whether reversible blockade of preganglionic sympathetic fibres of the heart, achieved by thoracic epidural anaesthesia, affects cardiac repolarization and thus confers an anti-arrhythmic effect. 2. Fifty-two men, aged between 28 and 65 years, were included in the study: 28 were patients scheduled for thoracic epidural anaesthesia (Group T) and 24 were patients scheduled for lumbar epidural anaesthesia (Group L). Epidural blockade was achieved with 0.5% isobaric bupivacaine solution. Measurements were taken from electrocardiogram fragments obtained before epidural anaesthesia and after detection of blockade (T1 or T8 segment sensory block in Groups T and L, respectively). Correction of the QT interval was calculated using Bazett's formula (QTcb), Fridericia's correction (QTcf) and the Framingham formula (QTcF). Transmural dispersion of repolarization (TDR) was determined using the Tpeak--Tend time, where Tpeak is the peak of the T wave and Tend is the end of the T wave. 3. Significant shortening of the QTcb interval and TDR was detected after blockade in Group T. However, there were no changes in the ECG parameters in Group L. 4. In conclusion, reversible blockade of preganglionic sympathetic fibres to the heart, achieved by thoracic epidural anaesthesia, results in a reduction in QTcb, as well as the TDR. These changes may explain the anti-arrhythmic action seen with central blockade.

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Effects of Thoracic Epidural Anaesthesia on Cardiac Repolarization

Owczuk¹,

Steffek²,

Wujtewicz³

et al. 2009

Clin Exp Pharma Physio

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“…Recently, we observed that laryngoscopy and tracheal intubation provoked QTc prolongation without significant changes in the T peak – T end time [22]; we concluded that this may explain the extremely low incidence of TdP in connection with intubation, in spite of the observed increase in repolarisation time. The ability to reduce TDR is characteristic of thiopental, a drug that prolongs QTc time, and explains the safe usage of this barbiturate in individuals with long QT syndrome [23].…”

Section: Discussionmentioning

confidence: 99%

Influence of promethazine on cardiac repolarisation: a double‐blind, midazolam‐controlled study

Owczuk¹,

Twardowski²,

Dylczyk-Sommer³

et al. 2009

Anaesthesia

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Drugs used in anaesthesia may provoke torsadogenic changes in cardiac repolarisation. The aim of this study was to assess the effect of promethazine on the parameters of ventricular repolarisation: QTc interval and transmural dispersion of repolarisation. Forty patients were randomly allocated to receive promethazine (25 mg) or midazolam (2.5 mg). Changes in the ECG and arterial blood pressure were recorded. Correction of QT interval was calculated using Bazett's formula and Fridericia's correction; transmural dispersion of repolarisation was determined as T(peak)-T(end) time. Significant prolongation of QT interval, corrected with both formulae, was detected in patients receiving promethazine, while no change in the QTc value was observed in the midazolam group. There were no significant differences in T(peak)-T(end) time either between or within the groups. In conclusion, promethazine induces significant QTc prolongation but the lack of influence on transmural dispersion of repolarisation makes the risk of its torsadogenic action very low.

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“…Moreover, there are reports of a decreased duration of corrected QT after this procedure [15]. The observed prolongation of the period of ventricle repolarisation following laryngoscopy and intubation could be related to increased activity of the sympathetic system and increased catecholamine release [7, 16, 17]. Apart from alterations of electrophysiological parameters, these phenomena are often accompanied by an increase in heart rate and arterial blood pressure.…”

mentioning

confidence: 99%