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myocardial protection intra-op

Description of the problem
This topic deals predominantly with atrial fibrillation (AF) and atrial flutter (AFlutter), the two most common SVTs occurring during cardiac surgery. For a comprehensive review of other SVT subtypes and their clinical features, see the chapter “SVT (non-cardiac surgery).”

SVTs, in particular AF, have a significant impact on mortality and morbidity, by increasing stroke and thromboembolic risk, increasing progression to ventricular arrhythmias, precipitating hemodynamic instability, as well as increasing hospital stay and increasing risks from iatrogenic interventions (anticoagulation, pacemakers, arrhythmic drugs).

SVT occurring in the setting of cardiac surgery requires several key considerations:

  1. Preoperative assessment: how to manage patients with a history of SVT, how to manage patients taking oral anticoagulation, and what predisposing factors are associated with development of SVT
  2. Perioperative period: how to prevent de novo or recurrent SVTs from occurring
  3. Postoperative period: which SVTs tend to occur depending on the type of cardiac surgery

AF is the most common SVT occurring in the perioperative period for cardiac surgery, and it occurs in an estimated 30% of patients undergoing coronary artery bypass grafting (CABG), 40% of those undergoing valvular surgery, and 50-55% of patients having combined procedures.

Furthermore, the mechanisms of onset of SVT, as well as the type of cardiac surgery, also require individual consideration, as patients with congenital heart disease undergoing Senning or Mustard repairs will have different comorbidities than patients with degenerative valvular disease, those with ischemic heart disease, or those requiring orthotopic cardiac transplantation.

Patients with surgically repaired congenital heart disease may experience tachyarrhythmias/SVTs as a result of hemodynamic disturbances, and thus an extensive evaluation of residual shunts/intracardiac pressures is often warranted sooner than for those with SVTs and acquired heart disease.

Atrial tachycardias are common after mitral valve surgery, occurring in the early postoperative period (due to transient ischemia, pericarditis, type of surgical approach) as well as in the late postoperative period (multifactorial – aging, myocardial remodeling).

Clinical symptoms of SVT

  1. May be asymptomatic
  2. Regular, episodic, or irregular palpitations
  3. Chest pain at rest or with exertion
  4. Dyspnea at rest or with exertion
  5. Weakness or fatigue
  6. Lightheadedness
  7. Exercise intolerance