Ann Thorac Surg 2009;87:1946-1948. doi:10.1016/j.athoracsur.2008.11.009
© 2009 The Society of Thoracic Surgeons
Case Reports
Coronary Artery Dissection After Surgical Cryoablation Procedure
Fabien Doguet, MDa,*,
Vincent Le Guillou, MDa,
Pierre Yves Litzler, MD, PhDa,
François Bouchart, MDa,
Catherine Nafeh-Bizet, MDa,
Alain Cribier, MDb,
Jean Paul Bessou, MDa
a Department of Thoracic and Cardiovascular Surgery, Rouen University Hospital, Rouen, France
b Department of Cardiology, Rouen University Hospital, Rouen, France
Accepted for publication November 3, 2008.
* Address correspondence to Dr Doguet, Department of Thoracic and Cardiovascular Surgery, Rouen University Hospital, 1, rue de Germont, Rouen, 76000, France (Email: fabien.doguet{at}chu-rouen.fr).
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Abstract
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Cryoablation can be used to treat atrial fibrillation (AF) surgically. We describe a 71-year-old woman who underwent cryoablation after 6 months of AF. Four hours post-surgery, electrocardiographic changes were observed in the circumflex artery territory associated with hemodynamic instability, which responded to inotropic agents. Angiography revealed a diffuse circumflex artery spasm with a heterogeneous aspect of the posterior branch evoking a dissection. Platelet anti-aggregant and trinitrine therapy were started. Recovery was uneventful and the patient was discharged on day 13. Cryoablation-associated circumflex artery dissection is rare. Caution is required when locating the ablation lines to avoid coronary artery injury.
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Introduction
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We describe a case of circumflex artery injury in a 71-year-old woman who had undergone mitral valve replacement, tricuspid annuloplasty, and an atrial fibrillation (AF) cryoablation procedure. The patient suffered from severe mitral insufficiency due to chordae rupture on A2, P2, P3, with a bileaflet prolapse, and she also had a 6-month history of AF.
On presentation the patient had dyspnea (New York Heart Association functional class II). Coronary angiography revealed normal coronary arteries. She subsequently underwent mitral valve replacement with a biological prosthesis, tricuspid annuloplasty, and an AF endocardial cryoablation procedure with the ATS CryoMaze Surgical Ablation System (ATS Medical Inc, Minneapolis, MN). The ablation procedure was performed under cardiopulmonary bypass. Normothermic blood continuous retrograde cardioplegia was used during the procedure. Each lesion was created for 1 minute at –150°C. The following lesions were created: two endocardial lesions surrounding the pulmonary veins, another lesion set to the P2 segment of the mitral annulus, and a line lesion between the left atrial appendage and left pulmonary veins. The left atrial appendage was surgically closed. Aortic cross-clamp and extracorporeal-circulation times were 90 and 132 min, respectively.
Four hours post-surgery, electrocardiographic changes were observed in the circumflex artery territory, associated with hemodynamic instability. Inotropic agents were necessary. The troponin Ic maximal value was 55 µg/L (normal, < 3 µg/L). Emergency angiography revealed a diffuse circumflex artery spasm with a heterogeneous aspect of the posterior branch of the circumflex artery evoking local dissection (Fig 1). Platelet anti-aggregant (acetylsalicylic acid, 160 mg/day) and trinitrine therapy was started. The patient was weaned from inotropic agents on day 3. Her post-intensive care unit course was uneventful, and she was discharged on day 13 in AF. A transthoracic echocardiogram revealed good left ventricular function with light septo-apical hypokinesia.
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Comment
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Radiofrequency, microwaves, and cryoablation have all been used to treat AF surgically. However, the efficacy of these approaches is unclear. The creation of continuous linear transmural atrial lesions, which act as an electrophysiological conduction block, is doubtful. These alternative sources of energy should be capable of providing an epicardial or endocardial approach with minimal collateral damage when compared with the "cut and sew" technique and risk of bleeding. The presence of an additional mitral valve annulus lesion can sometimes induce circumflex artery injury when using alternative energies. Another risk associated with the endocardial approach is pulmonary vein stenosis and esophageal perforation. Furthermore, the mitral annulus "connecting lesion" can not be reached epicardially without risking injury to the circumflex artery. In fact, the misapplication of epicardial energy has previously resulted in left main coronary injury [1].
Cryoablation is the most established alternative energy source used to complete the maze III procedure, as well as to perform spot ablations near the tricuspid and mitral annuli. One advantage of cryoablation is that it causes little adjacent structural damage. In contrast with hyperthermic energy sources, architectural integrity is preserved because collagen tissue and the vasculature are unaffected. There is also a low risk of bleeding, perforation, or collateral damage.
We believe that circumflex artery injury, as described in our patient, is an unknown complication of cryoablation. It is difficult to determine whether the placement of the annular sutures or cryoablation was responsible for the circumflex artery injury. We believe that it was caused by the cryoablation procedure for several reasons.
First, the delay between electrocardographic changes and surgery is not the same if artery injury is due to suture misplacement. In this case, hemodynamic instability usually occurs immediately after weaning off cardiopulmonary bypass or if weaning is impossible. The biological effects of freezing occur in three phases: (1) phase one (freeze/thaw), in which the intracellular and extracellular ice crystals form according to the thermal distribution. The crystals compress and distort adjacent cell membranes, mitochondria, and cytoplasmic organelles, causing irreversible lesions evident within hours [2]; (2) phase two (inflammation), in which hemorrhage appears and is prominent 48 hours after the injury, leading to subsequent edema and apoptosis; (3) phase three, in which inflammatory cells infiltrate, capillaries ingrow, and fibrin is deposited within 1 week. The evolution of phase one could explain why electrocardiographic changes occurred 4 hours after surgery (6 hours after cryoablation), and not immediately after termination of cardiopulmonary bypass.
Second, the type of circumflex artery injury seen in our case is not the same as that observed in isolated mitral valve surgery. When circumflex artery injury is due to suture misplacement, the lesion observed is an occlusion or a distortion of the artery [3]. A left main coronary artery lesion after microwave epicardial ablation has been described by Manasse and colleagues [1]. The artery injury appeared on postoperative day 90; the ablation procedure consisted of pulmonary vein isolation. In our case, the artery lesion was observed almost immediately post-surgery, and the procedure was endocardial. Raza and colleagues [4] reported a circumflex artery injury after minimally invasive mitral valve repair and left atrial cryo-maze. An electrocardiogram showed an ST elevation when closing the incision in the operating room. Coronary angiography showed total occlusion at the mid-segment of the atrioventricular groove circumflex artery. Angioplasty was performed. Intravascular ultrasound demonstrated an external hematoma, with compression of the circumflex artery related to one of the sutures around the P1 segment of the posterior mitral valve leaflet.
The type of coronary lesion was not the same in these three cases, with stenosis in one, hematoma with external compression in the second, and "cryo-traumatism" in our case, with localized dissection and spasm. Unfortunately, we do not have intravascular ultrasound to precisely determine the type of coronary lesion.
This spot lesion suggests that the left atrial wall is thinner in this zone, perhaps associated with a too-long lesion time. Another explanation is that the cryoablation line was not in the optimal place (inappropriate placement of the probe), near the circumflex artery course. One possibility was to perform angioplasty of the coronary lesion with a bare metal stent. We decided to treat this lesion medically with anti-coagulant therapy because of good flow in the circumflex artery and the good hemodynamic state of the patient after administration of inotropic agents.
Circumflex artery dissection due to cryoablation is a rare acute complication that can respond to medical treatment. Caution is required when positioning the ablation lines to avoid coronary artery injury.
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References
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- Manasse E, Medici D, Ghiselli S, Ornaghi D, Gallotti R. Left main coronary arterial lesion after microwave epicardial ablation Ann Thorac Surg 2003;76:276-277.[Abstract/Free Full Text]
- Viola N, Williams MR, Oz MC, Ad N. The technology in use for the surgical ablation of atrial fibrillation Semin Thorac Cardiovasc Surg 2002;14:198-205.[Medline]
- Grande A, Fiore A, Masseti M, Vigano M. Iatrogenic circumflex coronary lesion in mitral valve surgery: case report and review of the literature Tex Heart Inst J 2008;35:179-183.[Medline]
- Raza JA, Rodriguez E, Miller MJ. Successful percutaneous revascularization of circumflex artery injury after minimally invasive mitral valve repair and left atrial cryo-MAZE J Invasive Cardiol 2006;18:E285-E287.[Medline]
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Abstract
Introduction
