Having worked on both sides of the cardiac surgery “Ether Screen” (AKA “the blood-brain barrier”) I can attest that atrioventricular (AV) disruption is a catastrophic and more often than not lethal complication of mitral valve replacement (MVR) surgery. Fortunately, it is fairly rare, occurring in fewer than 1 in 1,000 minimally invasive MVR operations in a recent report by McClure and colleagues and 1.2% in another recent series of MVR procedures reported by Schuetz et al. This complication is not limited to mitral valve replacement surgery, having been reported during off-pump coronary artery bypass grafting.
In their case report “Atrioventricular Disruption After Mitral Valve Replacement: The Role of Intraoperative Transesophageal Echocardiography,” Dr. Jason Chui and colleagues from the Department of Anesthesia and Pain Management of the University of Toronto, nicely review the manifestations and presumed mechanisms that contribute to this complication. They suggest that 3D TEE may provide more accurate and earlier diagnosis.
Does this imply that we should all be examining the mitral annulus with 3D TEE following MVR and if so, would earlier diagnosis lead to more successful treatment of this complication? This raises a question regarding the sensitivity and specificity of this examination, which is likely greatly influenced by the skill of the echocardiographer. Because this is a rare complication, it is nearly impossible to study in any reasonably sized study. A false positive diagnosis could lead to unnecessary and possibly harmful surgical intervention. The latter is complicated because the typical location of these AV disruptions is in the region of the circumflex coronary artery, which can be damaged during attempts at surgical repair. Finally, it is not obvious how the AV disruption contributed to the progressive decline in biventricular systolic function in the absence of massive bleeding described in this report. Was the latter perhaps unrelated to the AV disruption and simply the consequence of the MVR?