What is atrioventricular (AV) groove dissociation?

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Last updated: October 27, 2026 • View editorial policy

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Atrioventricular (AV) Groove Dissociation

AV groove dissociation (also called AV groove disruption or separation) is a catastrophic complication of mitral valve surgery where the junction between the left atrium and left ventricle tears apart, creating a communication between the left ventricular cavity and the pericardial space or atrioventricular groove tissues. 1

Classification

Miller and colleagues in 1979 described three distinct types of AV groove disruption 1:

  • Type 1: Annular separation - The tear occurs at the mitral annulus itself, separating the atrial tissue from the ventricular tissue
  • Type 2: Posterior ventricular rupture - The left ventricular free wall ruptures posterior to the annulus
  • Type 3: Midventricular tear - A tear occurs in the mid-portion of the left ventricular wall

Clinical Context and Risk Factors

This complication occurs most commonly during mitral valve replacement surgery, particularly when dealing with mitral annular calcification (MAC) 1. The disruption happens when:

  • Extensive annular decalcification is performed ("Resect" strategies)
  • Heavy calcification extends into surrounding tissues
  • Aggressive debridement weakens the structural integrity of the AV groove
  • Sutures are placed through friable, calcified tissue

Important caveat: Chordal preservation during mitral valve surgery was noted to be protective against AV groove disruption 1.

Mortality and Outcomes

The mortality rate for AV groove disruption is devastating, with in-hospital mortality reaching 56% in contemporary series 2. This represents one of the most lethal complications in cardiac surgery, requiring immediate recognition and surgical repair.

Detection and Management

The disruption can be detected intraoperatively using transesophageal echocardiography (TEE), which shows blood flow leaving the left ventricular outflow tract and expanding into surrounding tissues during systole 3.

External repair is performed in 94% of cases 2, typically requiring:

  • Immediate return to cardiopulmonary bypass
  • External buttressing of the disrupted groove
  • Pericardial patch reconstruction of the defect 1
  • Multiple pledgeted sutures to reinforce the repair

Second-look operations for excessive mediastinal hemorrhage are necessary in approximately 67% of patients 2.

Prevention Strategies

Modern surgical approaches to MAC aim to prevent this complication through 1:

  • "Respect" strategies: Working around calcification with limited or no resection, using oversized annuloplasty techniques
  • Selective "Resect" strategies: Complete en bloc decalcification with sliding atrioventriculoplasty or pericardial patch reconstruction, reserved for lower-risk patients with appropriate anatomy
  • Risk stratification based on extent of calcification, patient comorbidities, and surgical expertise

The choice between these approaches should be tailored to the severity of MAC on CT imaging and the patient's baseline risk profile 1.

References

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