Catheter Ablation for Supraventricular Tachycardia

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SAMPLE EXCERPT
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PRE-PROCEDURE
INDICATIONS
  • Hemodynamically intolerant supraventricular tachycardia (SVT)
  • Recurrent symptomatic SVT
  • Infrequent or a single episode of SVT if the patient is intolerant or does not desire medical therapy
  • Wolff-Parkinson-White (WPW) syndrome with symptomatic arrhythmias including atrial fibrillation or atrioventricular nodal reentrant tachycardia (AVRT)
  • Preexcitation with palpitations
  • Ablation of asymptomatic preexcitation is considered reasonable
CONTRAINDICATIONS
  • Patient refusal
  • Inability access the heart because of venous obstruction
  • Known intracardiac clot where catheters are to be placed
  • Uncontrolled infection or other acute medical condition
EQUIPMENT
  • Sterile mask, gown, gloves
  • Sterile prep solution for access site
  • Sterile drapes
  • Sterile introducer sheaths, J wires, 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 electrocardiogram 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 SVT ablation are placed in the high lateral right atrium (RA), near the His bundle on the septal side of the tricuspid valve, coronary sinus, and right ventricle (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 left atrium (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 eustachian valve extends to become the tendon of Todaro, which forms the posterior border of the triangle of Koch. The inferior border of the triangle of Koch is the ostium of the coronary sinus. The slow pathway inputs to the AV node are usually located in the region inferior to the AV node anterior to the coronary sinus ostium. The fast pathway inputs of the AV node are located near the apex of the triangle of Koch but are not usually targeted for ablation because of the proximity to the compact AV node itself. The tricuspid valve marks the anatomic boundary between the RA and RV and is the location of accessory pathways, if present.
  • LA anatomy includes the appendage, pulmonary vein portion, and the vestibule. The esophagus runs posterior to the LA.
    • Nodes and networks of specialized myocardial cells make up the cardiac conduction system. The system consists of the SA node, AV node, 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 right atrial appendage and lateral atrial wall near the SVC.
      • AV node: Located within the atrial component of the muscular AV septum, superior to the septal cusp 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.
      • WFW syndrome is caused by Kent bundles that connect the atrial and ventricular myocardium at some point around the valve annuli.

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.
  • Patient should be cautioned to watch for swelling or bleeding at the femoral puncture site and to report these immediately to the nursing 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
    • AV 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 (higher with left-sided ablation)
  • The potential for heart block exists, depending on nearness to the AV node and His bundle. It is higher if fast pathway ablation is performed. Risk of heart block with slow pathway ablation for AVNRT is 0.5% to 1.0%. Cryoablation can lessen risk, at the expense of higher recurrence rate.
  • 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
  • Remapping and evaluation may be necessary if the patient has recurrence of palpitations or documented arrhythmia after ablation therapy.
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