Transient QT prolongation with torsades de pointes tachycardia after ablation of permanent junctional reciprocating tachycardia

Perioperative torsade de pointes: a systematic review of published case reports

BACKGROUND

Torsade de pointes is a rare but potentially fatal arrhythmia. More than 40 cases of perioperative torsade de pointes have been reported in the literature; however, the current evidence regarding this complication is very limited. To improve our understanding, we performed a systematic review and meta-analysis of all published case reports of perioperative torsade de pointes.

METHODS

MEDLINE was systematically searched for cases of perioperative torsade de pointes. We included patients of all age groups and cases that occurred from the immediate preoperative period to the third postoperative day. Patient and case characteristics as well as QT interval data were extracted.

RESULTS

Forty-six cases of perioperative torsade de pointes were identified; 29 occurred in women (67%), and 2 episodes were fatal (case fatality rate: 4%). Craniotomies and cardiac surgery accounted for 40% of all cases. Preceding events identified by the authors were hypokalemia (12/46, 26%; 99% confidence interval [CI], 9%-43%) and bradycardia (7/46, 15%; 99% CI, 2%-28%). Drugs were implicated in approximately one third of the events (14/46, 30%; 99% CI, 13%-48%). The mean corrected QT (QTc) at baseline was 457 ± 67 milliseconds (minimum 320 milliseconds; maximum 647 milliseconds; data available in 27/46 patients). At the time of the event, the mean QTc increased to 575 ± 77 milliseconds (minimum 413 milliseconds; maximum 766 milliseconds; data available in 33/46 patients). On average, QTc increased by +118 milliseconds (99% CI, 70-166 milliseconds; P < 0.001) between baseline and after the torsade de pointes event. All patients, except for 2, had a substantial prolongation of their QTc interval at the time of the event.

CONCLUSIONS

This systematic review identified several common risk factors for perioperative torsade de pointes. Given the nearly uniform presence of a substantial QTc interval prolongation at the time of a torsade de pointes episode, increased vigilance for perioperative QTc interval prolongation may be warranted.

Cardiac Arrest Caused by Torsades de Pointes Tachycardia after Successful Atrial Flutter Radiofrequency Catheter Ablation

A 66-year-old woman underwent successful radiofrequency catheter ablation for long-lasting, drug refractory fast atrial flutter. Two days later she had a cardiac arrest due to torsades de pointes (TdP) tachycardia attributed to relative sinus bradycardia and QT interval prolongation. After successful resuscitation further episodes of TdP occurred, which were treated with temporary pacing. Because of concomitant systolic dysfunction due to ischemic and valvular heart disease she was finally treated with an implantable defibrillator. In conclusion we strongly advise prolonged monitoring for 2 or more days for patients with structural heart disease following successful catheter ablation for long lasting tachyarrhythmias.

AHA scientific statement: practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association Scientific Statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized electrocardiology and the American Association of Critical-Care Nurses

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas Computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide "best practices" for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, time frames, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Practice Standards for Electrocardiographic Monitoring in Hospital Settings

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide ‘best practices’ for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, timeframes, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Transient proarrhythmic state following atrioventricular junction radiofrequency ablation: pathophysiologic mechanisms and recommendations for management

The induction of complete heart block by radiofrequency ablation of the atrioventricular junction combined with pacemaker implantation has become an established therapy for rate control in patients with atrial fibrillation who are unresponsive to drugs. Reports of ventricular arrhythmias and sudden death after ablation have, however, raised concerns about safety. Ventricular arrhythmias are usually polymorphic and related to a phase of electrical instability due to an initial prolongation and then slow adaptation of repolarization caused by the change in heart rate and activation sequence. Structural heart disease, and other factors that predispose for the acquired long QT syndrome, seem to add to the risk. Ventricular activation and repolarization stabilize during the first week after the procedure. Routine pacing at 80 beats per minute during this phase is recommended, as well as in hospital monitoring for at least 48 hours. Patients with high-risk features for arrhythmias, such as congestive heart failure or impaired left ventricular function, may require pacing at higher rates. Adjustment of the pacing rate-although rarely below 70 beats per minute-is usually undertaken after a week in most patients, preferably after an electrocardiographic evaluation for repolarization abnormalities at the lower rate.