Atrial flutter surgery
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]
Overview
Due to the reentrant nature of atrial flutter, it is often possible to ablate the circuit that causes atrial flutter. This is done in the electrophysiology lab by causing a ridge of scar tissue that crosses the path of the circuit that causes atrial flutter. Ablation of the isthmus, is a common treatment for typical atrial flutter.
Surgery
Pre-Procedure Considerations
- Thorough history and physical examination
- Echocardiogram - to exclude structural heart disease
- Exercise testing
- Beta-blockers, calcium channel blockers and other drugs taken by the patient to control heart rate should be tapered and discontinued before the procedure
- Warfarin should be discontinued before the procedure to avoid bleeding complications from the procedure.
Procedure
Fine wires called catheters which can record the electrical activity of the heart are introduced into the heart through the veins of the leg (femoral veins usually). This procedure can be performed when the patient is either in sinus rhythm or in flutter. Radiofrequency energy (low-voltage, high-frequency electricity) is applied over the area of the heart causing the abnormal heart rhythm, permanently damaging small areas of tissue with heat. The ablated tissue will no longer be able to generate or propagate electrical impulses to other regions of the heart.[1]
Ablation in Atrial Flutter Type 1
Radiofrequency energy is directed typically in the 6 o clock direction on the tricuspid valve isthmus. Success rate is up to 95% and anticoagulation with warfarin should be continued for 4-6 weeks post procedure.[2]
Ablation in Atrial Flutter Type 2
Type 2 atrial flutter is due to intraatrial reentrant circuits and hence additional mapping of the left atrium may be necessary while performing ablation for this type of flutter. Recurrence is common after ablation therapy in this type compared to type 1 flutter.
Advantages
- Permanent restoration to sinus rhythm[3]
- Higher success rate of nearly 95%
- Improved quality of life (decreased hospitalizations, improved cardiac functioning)
Complications
- Cardiac perforation - can lead to leakage of blood into the pericardial sac causing tampoade and hypotension. It is seen in 1 out of 200 patients undergoing ablation for treatment.
- Bradycardia - due to damage to normal conduction system. Treatment is by artificial pacemaker.
- Damage to the veins of the leg
- Increased stroke risk - 4-6 weeks of anticoagulation with warfarin is prescribed to prevent stroke
- Atrial fibrillation - long term risk in patients undergoing ablation for flutter. Presence of an underlying structural heart disease increases the risk even more. Pre-ablation left atrial size has been shown to be an independent risk factor for the development of these secondary atrial arrhythmias.
- Recurrence - common with type 2 flutter
- Pain
Measurement of Successful Ablation
- Corridor of widely split double potentials 90-110 ms.
- Transisthmus conduction intervals
- Counter clockwise defined as interval between stimulus on lateral wall and proximal coronary sinus electrode.
- Clockwise defined as interval between stimulus in proximal CS and electrodes lateral to line of block.
- Interval measured at 500, 400, and 300 ms. If this value increased by 50% or more this was defined as successs or 150ms.
- Pacing at multiple sites, AD>BD and DA>CA.
- Bipolar electrograms lateral to line and pace from Proximal CS. Transition of polarity from positive to negative.
- 3 pacing site protocol: Pace at two sites lateral (L1R and L2R) to the line on block and on the septal site (S) of the line. Measure the conduction delay from the pacing site to the R wave on the QRS (L1 to R, L2 to R and S to R). If (L1R-L2R) > 0 and (L1R-SR) > 94 then there is a 100% sensitivity and 98% specificity.[4]
References
- ↑ Poty H, Saoudi N, Nair M, Anselme F, Letac B (December 1996). "Radiofrequency catheter ablation of atrial flutter. Further insights into the various types of isthmus block: application to ablation during sinus rhythm". Circulation. 94 (12): 3204–13. doi:10.1161/01.cir.94.12.3204. PMID 8989130.
- ↑ Schwartzman D, Callans DJ, Gottlieb CD, Dillon SM, Movsowitz C, Marchlinski FE (November 1996). "Conduction block in the inferior vena caval-tricuspid valve isthmus: association with outcome of radiofrequency ablation of type I atrial flutter". J. Am. Coll. Cardiol. 28 (6): 1519–31. doi:10.1016/s0735-1097(96)00345-2. PMID 8917267.
- ↑ O'Callaghan PA, Meara M, Kongsgaard E, Poloniecki J, Luddington L, Foran J, Camm AJ, Rowland E, Ward DE (August 2001). "Symptomatic improvement after radiofrequency catheter ablation for typical atrial flutter". Heart. 86 (2): 167–71. doi:10.1136/heart.86.2.167. PMC 1729856. PMID 11454833.
- ↑ Calkins H, Canby R, Weiss R, Taylor G, Wells P, Chinitz L, Milstein S, Compton S, Oleson K, Sherfesee L, Onufer J (August 2004). "Results of catheter ablation of typical atrial flutter". Am. J. Cardiol. 94 (4): 437–42. doi:10.1016/j.amjcard.2004.04.058. PMID 15325925.