In the present case, extensive myocardial infarction due to the intraoperative occlusion of both coronary ostia by prosthetic valve was recorded as the cause of death. Since there are, to date, no reports of similar deaths in patients undergone to AVR, our report provides useful information on this complication of AVR.
Coronary ostial stenosis following AVR is believed to occur in 1% to 5% of AVR procedures. It is a life threatening complication which, generally, becomes evident from 1 to 6 months after the operation [5
]. Several different mechanisms which include the possibility of microinjuries and local hyperplastic reaction related to the infusion pressure and/or low temperature of cardioplegic solution and overdilation of the vessel by the tip of the cardioplegic catheters are thought to be involved [1
]. Other mechanisms were hypothesized such as widespread intimal thickening and fibrous proliferation in proximity of the aortic root, presumably as a reaction to turbulence around aortic ball valve prostheses. An immunological reaction to the heterograft after AVR has been considered in cases of bilateral ostial coronary arteries stenoses revealing several months following the surgical procedure [1
]. On the basis of these evidences the exact mechanism underlying late coronary ostial stenosis following AVR is unclear.
Anecdotal reports describe the rare occurrence of acute coronary ostial stenosis; right ostial occlusion from aortotomy sutures and ostial post-traumatic thrombosis due to aortic retractor have been described [2
]. In exceptional cases, embolism from debris, more often calcium related to aortic valve decalcification, or left atrial thrombectomy can be involved [1
]. Coronary artery spasm has been recognized as a possible cause of hemodynamic and arrhythmic instability after aortic valve replacement [6
]. Occasionally, secondary fibrosis in the area of suture placement may occur causing ostial stenosis [7
]. Finally, use of surgical glue in aortic surgery, or compression from outside due to the glue used to protect the anastomosis may cause stenosis of one or both coronary ostia [8
Conclusively, there is a reasonable body of evidence that acute coronary ostial stenoses may occur, even if rarely, after AVR and this complication may be life threatening if not promptly recognized, leading to myocardial ischemia, infarction, or fatal arrhythmia. Consequently, it is important to have an high index of diagnostic suspicion if circulatory collapse and/or signs of myocardial ischemia occur soon after surgery. Transesophageal echocardiography can be useful in diagnosis of acute complications of cardiac surgery; however urgent coronary angiography remains the gold diagnostic tool [8
In our case, both coronary ostia were iatrogenically occluded by the prosthesis: the right one appeared to be entrapped by a stitch and the left one was occluded by prosthetic post. Neither intraoperative transesophageal echocardiography or postoperative coronary angiography were performed, so impeding to reach a prompt diagnosis.
From a clinical point of view, surgeons must have an high level of vigilance regarding the occurrence of acute myocardial ischemia soon after AVR and must be ready to perform either an intraoperative verification of patency or an early coronary angiography during ICU stay since these diagnostic tools may reveal mechanisms underlying ischemia which could make necessary a surgical approach (coronary stenting, device removal and/or re-replacement with a smaller valve size with or without annular enlargement) [3