Abstract
Mitral valve repair is becoming an increasingly frequent surgery for patients with mitral valve regurgitation. Iatrogenic coronary artery injury and ischemic myocardial compromise have been previously reported in the literature as a rare but serious complication of surgical mitral valve repair. This potentially life-threatening complication should be considered and quickly recognized during perioperative mitral valve repair or replacement to prevent morbidity and mortality. To increase awareness and to prevent this complication from being missed in the future, we present a case report of iatrogenic left circumflex artery dynamic occlusion and subsequent myocardial infarction from mitral valve annuloplasty resulting in severe peri-operative heart failure and death.
Highlights
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A case of left circumflex coronary artery injury during mitral valve repair.
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Left circumflex artery injury can also occur with mitral valve replacement including with certain devices used for percutaneous mitral valve repair.
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Left circumflex coronary artery injury can lead to severe complications including death and prompt recognition of this complication is imperative.
1
Introduction
Mitral valve repair or replacement is the treatment for severe mitral regurgitation and this procedure is becoming increasingly more frequent [ ]. Left circumflex (LCX) coronary artery injury is a known but rare complication of mitral valve surgery caused by annular ring sutures [ , ]. It has been suggested that this complication occurs in 1.8% to 2.7% of patients undergoing mitral valve surgery, although data on this topic is limited [ , ]. The risk of this complication may be related to the proximity of the LCX artery to the posterior segment of the mitral valve. Multiple mechanisms of arterial injury have been suggested and are related to direct injury to the vessel with the surgical suture and surrounding tissue distortion resulting in LCX artery dynamic or functional stenosis or occlusion causing a myocardial infarction [ ].
2
Case report
A 67-year-old male with hypertension, type II diabetes, hyperlipidemia, chronic diastolic congestive heart failure and severe mitral regurgitation (Video 1) leading to gradually worsening pulmonary hypertension and right sided heart failure presented to an outside hospital with volume overload. Cardiac catheterization ten months prior showed “minimal coronary artery disease in the right coronary artery” ( Fig. 3 , Video 1) with the normal left coronary system ( Fig. 3 , Video 2). On presentation, transthoracic echocardiogram (TTE) confirmed severe mitral regurgitation with moderate right ventricular dysfunction, pulmonary hypertension, and normal left ventricular ejection fraction (EF) with no wall motion abnormalities. Cardiac surgery was consulted and the patient underwent mitral valve repair, after optimal treatment of acute heart failure, for flail primary and secondary P2 and partial P3 chordae with four sets of neochordae (three on P2 and one on P3) and a twenty-seven millimeter annuloplasty ring. No mitral regurgitation was seen on post-operative transesophageal echocardiogram. Immediately following, the patient failed cardiopulmonary bypass (CPB) weaning and was found to have a new biventricular failure (right ventricular akinesis and depressed left ventricular function with an EF of 10%). An intraoperative electrocardiogram (ECG) monitoring revealed new ST segment elevation in leads II, III, and aVF. Interventional cardiology was consulted and a selective right coronary artery (RCA) angiogram was performed. The previously documented mild RCA lesion was without any significant change. Unfortunately, he also developed significant coagulopathy leading to intraoperative bleeding requiring several blood transfusions. With refractory cardiogenic shock, central extracorporeal membrane oxygenation (ECMO) cannulae were placed and the patient returned to the intensive care unit with an open chest. Given new biventricular heart failure and cardiogenic shock, he was then transferred to our tertiary care facility on postoperative day one for further treatment.
Upon arrival, the patient went to the operating room for a chest wash out for mediastinal bleeding and to attempt conversion of central ECMO to peripheral in order to close his chest. An intraoperative transesophageal echocardiogram (TEE) continued to show severely reduced left ventricular systolic function at 10% and severely reduced right ventricular function. A 12‑lead electrocardiogram showed inferolateral ST elevations ( Fig. 1 ) raising concerns for LCX territorial involvement. Coronary angiogram was performed confirming a kink in a large sized co-dominant LCX ( Fig. 4 , Video 4), causing severe flow obstruction (TIMI I) likely due to the tissue retraction from the surgical sutures. The right coronary artery (RCA) angiogram also showed a long segment 80% mid and distal vessel stenosis ( Fig. 5 , Video 6) with TIMI II flow, which is believed to be due to the intraoperative direct injury to RCA from the ECMO inflow cannula. Although delayed, but a successful percutaneous coronary intervention (Video 7) (PCI) with placement of drug eluting stents to LCX (Video 5) (3.5 × 28 mm drug eluting stent) and RCA (4 × 20 mm drug eluting stent to mid, and 3 × 38 mm drug eluting stent to distal) was performed obtaining TIMI III flow. Initially, a 3 × 20 mm balloon was crossed across the LCX lesion to assess for the length of stent. It was noted that the kink in LCX was shifted to the edges of the above balloon ( Fig. 4 ). So a longer stent was chosen with successful PCI without any residual kinks in the LCX artery ( Fig. 4 ). A repeat TTE revealed continued biventricular heart failure without any meaningful recovery of his heart functions failing ECMO weaning trials. Left ventricular assist device placement as a bridge to heart transplant was offered to the patient but was declined by the family based on patient’s own wishes expressed prior to the valve surgery. The patient spent eleven days on ECMO with no improvement. Honoring patient’s wishes, family elected to withdraw ECMO support and the patient expired.
3
Discussion
Given the proximity of the left circumflex coronary artery to the posterior portion of the mitral valve annulus as it courses through the atrioventricular groove ( Fig. 2 ), the LCX artery is susceptible to unintended manipulation and vascular injury during mitral valve repair or replacement. This potentially life-threatening complication can easily be masqueraded by subclinical presentation and other confounding causes of ischemia or impaired left ventricular contractility. Hiltrop et al. [ ] previously described the mechanisms of arterial injury after reviewing forty-four cases in the literature. The mechanisms include entrapment with an encircling suture, obliteration of the artery by a suture through the artery lumen, coronary perforation, thrombosis due to laceration of the endothelium, vascular distortion caused by tissue retraction causing a dynamic or fixed occlusion, laceration of the artery resulting in localized hemorrhage or subintimal hematoma leading to external compression, and external compression by the annuloplasty ring [ ]. Furthermore, they found a wide range of clinical presentations associated with this complication including asymptomatic ischemic EKG changes, new wall motion abnormalities on echocardiogram, refractory arrhythmias, hypotension, and difficulty in CPB weaning. In this analysis, 63% of patients had their myocardial compromise detected during CPB weaning but only 17% were diagnosed to have LCX injury prior to the weaning trial. A 97% of patients had EKG findings consistent with myocardial ischemia with 68% of the patients experienced ST segment elevation myocardial infarctions ( Fig. 6 ). Standard 5‑leads intra-operative EKG monitoring used to monitor ischemia during cardiac surgeries has its’ own limitations with a large area of myocardium including right ventricle and the posterior left ventricular wall being in a blind spot. For treatment, 42% (n = 15) underwent a surgical approach (bypass grafting or correction of sutures) with 87% success and 58% (n = 21) were with treated with primary percutaneous intervention (PCI) with 81% success [ ]. There is also a case reported in the literature of delayed LCX partial occlusion due to mitral annular hemangioma formation after mitral valve replacement surgery [ ].
