Catheter Ablation: Atrial Flutter

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SAMPLE EXCERPT
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PRE-PROCEDURE
INDICATIONS
  • Single or recurrent episodes of atrial flutter, regardless of hemodynamic response, particularly if heart rate is hard to control
  • Atypical atrial flutter after antiarrhythmic medication has failed
CONTRAINDICATIONS
  • Patient refusal
  • Inability to access the heart because of venous obstruction
  • Intracardiac clot, especially in the LA
  • Inability of patient to take appropriate anticoagulation for at least 4 weeks after the procedure, if the patient is in atrial flutter at the time of the ablation
  • Uncontrolled infection or other acute medical condition
EQUIPMENT
  • Sterile mask, gown, gloves
  • Sterile prep solution for access site
  • Sterile drapes
  • Sterile introducer sheaths, J guidewires, and introducer needles
  • Lidocaine for local anesthesia
  • Syringes and small-gauge (25- or 30-gauge) needles for subcutaneous infiltration of local anesthetic
  • Ultrasound for vascular access (optional)
  • Intracardiac catheters and cables
  • Fluoroscopy system
  • Three-dimensional mapping system (optional)
  • Pacing stimulator
  • ECG and electrogram recording system
  • Radiofrequency generator or cryoablation system
  • Crash cart with intubation equipment, resuscitation drugs, external defibrillator, and pacing equipment
  • Oxygen source and delivery system, if necessary (nasal cannula, mask, etc)
  • Equipment for starting a peripheral IV, if necessary:
    • IV catheter (20-gauge)
    • Alcohol or other sterile prep swab
    • Tape or transparent sterile dressing for securing IV
    • Heparin lock for IV
    • Gauze or bandage for IV site
  • Medications for sedation, if necessary (eg, midazolam)
  • Dressing for femoral IV access site
ANATOMY
  • Electrophysiology studies are used to assess cardiac conduction and rhythm abnormalities. Studies are carried out by insertion of intracardiac catheters via the femoral, subclavian, or internal jugular vein. Catheters for atrial flutter ablation are placed in the coronary sinus and around the tricuspid valve. Some operators also place a catheter near the His bundle and in the RV.
  • Vascular access for catheter ablation via the femoral vein is described here. The femoral vein is located in the femoral triangle just medial to the femoral arterial pulsation, below the inguinal ligament.
  • Relationships of the Heart in the Chest
    • In situ, the right border of the heart is formed by the RA and superior vena cava (SVC) and inferior vena cava (IVC). The LA is the most posterior chamber of the heart and is not visible in the anteroposterior (AP) view in the cardiac silhouette.
    • The left and right phrenic nerves are in close proximity to the left atrial (LA) appendage and the SVC, respectively.
  • RA anatomy can be divided into three components: the appendage, the venous components, and the vestibule. (A fourth anatomic part, the septum, is shared by both atria). The appendage is separated from the venous parts of the atrium by a muscular ridge, the “crista terminalis,” which corresponds to the external cardiac groove marking the location of the sinoatrial (SA) node near the SVC. A small muscular flap, or Eustachian valve, arises near the entrance of the IVC and can form an obstacle to passage of the ablation catheter from the IVC into the RA. The CTI is the region between the tricuspid valve and IVC, the critical region involved in typical atrial flutter. The coronary sinus ostium is at the medial side of the CTI. The tissue in the CTI may be flat or may have extensive trabeculations from pectinate muscles. About 10% of patients have a deep pouch in the CTI. The right coronary artery is typically <5 mm below the CTI.
  • LA anatomyincludes the appendage, pulmonary vein portion, and the vestibule. The LA is posterior and left compared with the RA.
  • The cardiac conduction system
    • Nodes and networks of specialized myocardial cells make up the cardiac conduction system. The system consists of the SA node, AV node, His bundle, left and right bundle branches, and subendocardial ventricular conduction cells (Purkinje fibers).
      • SA node: An elliptical structure, 10 to 20 mm long, located in the epicardium in the sulcus terminalis, the groove between the RA appendage and lateral atrial wall near the SVC.
      • AV node: Located within the atrial component of the muscular AV septum, superior to the septal leaflet of the tricuspid valve inferiorly. Its arterial supply is from the dominant coronary artery at the crux of the heart.
      • His bundle: A direct continuation of the AV node that branches in the interventricular septum.
      • Right and left bundles: The right bundle is a narrow group of cells that extends toward the RV septum. The left bundle is a group of numerous fine intermingling fascicles that leave the bundle along its course in the muscular ventricular septum, forming a sheet on the LV septal surface. The left bundle separates into anterior and posterior fascicles.

PROCEDURE
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The full content of this section includes:
  • Step-by-step text instructions for performing the procedure
  • Clinical pearls providing practical clinical tips from medical experts
  • Patient safety guidelines consistent with Joint Commission and OHSA standards
  • Links to medical evidence and related procedures

POST-PROCEDURE
CARE
  • Patients should remain on bed rest for 2 to 6 hours to prevent bleeding at femoral access sites and refrain from significant physical activity for 5 to 14 days afterward.
  • Patients should be cautioned to watch for swelling or bleeding at the femoral puncture site and to report these immediately to the staff.
  • A recurrence of palpitations or other symptoms should prompt a repeat evaluation.
COMPLICATIONS
  • Risk of vascular injury caused by catheterization is reported to be 1% to 2%.
    • Hematoma
    • Retroperitoneal bleeding
    • Arteriovenous fistula formation
    • Pseudoaneurysm formation
  • Other complications of vascular access:
    • Pneumothorax (internal jugular or subclavian vein access)
    • Brachial plexus injury (subclavian vein access) or femoral nerve damage (femoral vein access)
  • Thromboembolic complications
    • Deep venous thrombosis
    • Pulmonary embolism
    • Stroke or other systemic embolism (with left-sided ablation or if patient is in atrial flutter at the start of the procedure)
  • The potential for heart block is about 1:200, especially if ablation is completed in the medial CTI.
  • If there is an atypical flutter ablation on the posterior left wall, atrial esophageal fistula formation is possible but is very rare.
  • As with any electrophysiology study and ablation, complications from sedation or anesthesia, coronary artery stenosis, valvular damage, ventricular arrhythmias, cardiac perforation with pericardial effusion or tamponade, and, rarely, death may occur.
RESULT ANALYSIS

Several strategies are possible to confirm block across the CTI.

  • An increase in trans-CTI conduction time and reversal in the conduction pattern of the lateral right atrial wall while pacing medial to the ablation line
  • Fixed and widely spaced double potentials along the line (>90 msec)
  • Change in P-wave morphology and PR interval when pacing lateral to the line
  • Fixed His-coronary sinus ostium time when pacing from the low lateral and mid lateral RA
  • Reversal of electrogram polarity on the opposite side of the ablation line from the pacing site
  • R or RS unipolar electrogram lateral to the line when pacing medially
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