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Interact CardioVasc Thorac Surg 2007;6:384-386. doi:10.1510/icvts.2006.141044 © 2007 European Association of Cardio-Thoracic Surgery
The ‘aortic rim’ recount: embolization of interatrial septal occluder into the main pulmonary artery bifurcation after atrial septal defect closure
a Department of Cardio-Vascular and Thoracic Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India-695 011 Received 29 July 2006; received in revised form 14 February 2007; accepted 16 February 2007
*Corresponding author. Tel.: +91 471 2524648; fax: +91 471 2446433.
Introduction: Percutaneous device closure of atrial septal defect (ASD) has emerged as an alternative to traditional surgical closure. Although reduced hospital stay, decreased morbidity and absence of a surgical incision are beneficial, other procedure- or device-related complications are coming into light. We report a rare complication of early embolization of the Blockaid septal occluder into the main pulmonary artery bifurcation associated with ‘aortic rim’ erosion and present a brief review of literature pertaining to the high incidence of complications associated with deficient or eroded ‘aortic rims’ necessitating surgical intervention. Material and methods: An 18-year-old male underwent successful percutaneous device closure of a 24.5 mm ASD after fulfilling institutional criteria for the procedure. The device used was a Blockaid septal occluder, a device morphologically similar to the Amplatzer device. The subsequent day, he had embolization of the device into the main pulmonary artery bifurcation, and underwent emergency surgical retrieval of the same with closure of the ASD. At surgery the ASD was found to have an eroded aortic rim. Comments: We believe that embolization of the percutaneous septal occluder in our patient was due to a combination of factors including an inadequate aortic rim; a grossly oversized device which eroded the aortic rim; and the Blockaid septal occluder, whose formally untested design and configuration could have led to its migration. Conclusion: Strict selection criteria governing an ‘adequate’ aortic rim, the size of the device, and the choice of the device may help reduce the incidence of complications like the rare, but potentially fatal embolization of the device into the pulmonary artery following percutaneous device closure of an ASD.
Key Words: Congenital; Acyanotic; Device; Embolism
Percutaneous device closure of atrial septal defect (ASD) has emerged as an alternative to traditional surgical closure [1]. Percutaneous closure is associated with less surgical morbidity, avoidance of a scar and reduced hospital stay. With this new technology being increasingly used, several complications have been identified [1]. We report a rare complication of early device embolization of the Blockaid septal occluder into the main pulmonary artery bifurcation associated with ‘aortic rim’ erosion and present a brief review of literature pertaining to the high incidence of complications associated with deficient or eroded ‘aortic rims’ necessitating surgical intervention.
An 18-year-old male evaluated initially by trans-thoracic and trans-esophageal echocardiography was found to have a classical ostium secundum type ASD, occupying the entire fossa ovalis, with margins of 22,12,15,12 and 4 mm for the superior, inferior, superior vena cava (SVC), inferior vena cava (IVC) and aortic rims, respectively. The total septal length measured on left atrial side was 54 mm. The patient satisfied all institutional criteria for percutaneous closure of the ASD, namely: (a) Isolated ostium secundum defect without any systemic or pulmonary venous anomaly; (b) left to right shunt 1.5:1; (c) maximum diameter of defect <35 mm in any plane; and (c) adequate rims: minimum of 7 mm for the superior, inferior, IVC and SVC rims and 3 mm for the aortic rim. During percutaneous closure, utilizing a standard sizing technique [2], the defect was ‘stretched’ sized to 24.5 mm with an inflatable Amplatzer sizing balloon. An oversized Blockaid septal occluder device (ASDSO-28, Shanghai shape memory, Alloy Company Ltd., China) of size 28 mm was chosen. The device is a self-expanding, self-centering, repositionable double-disc Nitinol device with a short cylindrical waist, and a left atrial disc slightly larger than the right atrial one. It is an exact morphological replica of the Amplatzer septal occluder (AGA Medical Corporation, Golden Valley, Minnesota, USA), but at a fraction of the cost. Using standard techniques, the exchange guide wire was placed into the left upper pulmonary vein and the device sheath introduced [2]. The device was inserted and deployed under fluoroscopic and trans-esophageal echocardiographic guidance. Prior to final release of the device, the stability of the position was checked by the ‘Minnesota maneuver’ [2]. Cessation of flow across the inter-atrial septum was confirmed on trans-esophageal echocardiography prior to final deployment of device. On the day following device closure, he developed mild chest discomfort. Clinical evaluation revealed an ejection systolic murmur with a wide fixed second heart sound. Chest roentgenogram showed the radio-opaque device in the area of the pulmonary artery (Fig. 1a). Check echocardiogram showed a left to right shunt at the atrial level and confirmed device migration into the main pulmonary artery at its bifurcation (Fig. 1b) without any significant obstruction to forward flow into the branch pulmonary arteries.
He underwent emergency surgery. Following aortic cross-clamping and cardioplegic arrest, the right atrium was opened on total cardiopulmonary bypass when a 3x2 cm ostium secundum defect was seen with a tear in the aortic rim of the defect. The device was palpable externally at pulmonary bifurcation and was grasped under external digital control with a long ‘Kelly’ clamp passed into the pulmonary artery via the tricuspid and pulmonary valves. It was gradually withdrawn through the pulmonary valve and out of the right atrium. The device (Fig. 2) was inspected to be intact, not fragmented and with areas of peri-device thrombosis. The ASD was closed with an autologous pericardial patch in a standard manner. Postoperative period was uneventful; check echocardiography showed no residual shunt or pulmonary regurgitation.
Surgical closure of an ASD is the gold standard of treatment, as defects of any size and number can be closed. Mortality rate approaches zero in most modern surgical series with major morbidity being rare [4]. Device closure of ASDs has emerged as an attractive alternative to surgical closure for less morbidity, lack of a scar and shorter hospital stay [1]. As the numbers of catheter-based interventions steadily increase, so are the numbers of reported complications, with a significant proportion of these necessitating surgical intervention [5]. A multi-centric study comparing outcomes of surgery and device closure showed a 24% incidence of complications in the surgical arm with only 7.2% in the device arm [8]. The reported incidence of surgery related complication in this isolated report is very high compared to others in literature [4], wherein a surgical complication incidence of about 8% is probably more representative of the general experience. Complications such as device dislocation and migration have been reported in a significant number of patients; cases with late erosion of the left atrial roof and of the aorta have appeared in several reports [6]. Fatal perforations of the left ventricle, peripheral embolization of the device and sudden death have also been reported after successful device closure [6]. Minor complications such as vascular injury occur relatively frequently. We now report a case of device embolization into the pulmonary artery bifurcation, which untreated could have led to right ventricular outflow tract obstruction or erosion of the pulmonary artery and fatal pulmonary artery hemorrhage. This complication is rare with only a few cases documented to date [7]. While assessing the suitability of the margins of an ASD for device closure by echocardiography, the following ‘rims’ are routinely assessed [5]:
While most clinicians adhere to the criteria concerning minimum requisite margins of the Superior, Inferior, SVC and IVC rims, the small or deficient aortic rim is often ignored with newer self-centering devices [3, 9]. In one report up to 40% of patients with deficient aortic rims underwent percutaneous closure of their ASDs [3]. We believe that the aortic rim is important, and a margin <5 mm may predispose to device embolization, both early and late. Reports also have indicted a deficient ‘aortic rim’ in the majority of cases associated with embolization or displacement of the device [5]. Most of these documented complications necessitated surgical management [5]. In our patient, though the aortic rim was a significant one and met institutional criteria, we believe that the minimum size of the rim may need to be revised. In our opinion, the grossly oversized occluder could have also led to erosion of this rim. This predilection for the ‘aortic rim’ erosion, in patients with device-defect mismatch, has been postulated to arise from a ‘see-saw’ grinding movement between the inflated left atrial segment of the device and the aortic sinus wall with each cardiac cycle [5]. The inherent tendency of interventionalists to grossly oversize the device to avoid device embolization, and paradoxically perpetuate this problem, has also been reported [5]. The initial success of percutaneous device closure of ASDs has spurned the growth of many percutaneous devices worldwide, one of them being the Blockaid septal occluder. Though literature regarding trial use of this device is lacking, the device has been immensely popular in the developing world, owing primarily to its cheaper cost. We believe that, though relatively successful, there is the need for formal trials of such devices and their designs, prior to their safe use. We postulate the embolization of the percutaneous septal occluder in our patient to a combination of factors: a significant but still inadequate aortic rim; a grossly oversized device which eroded the aortic rim; and the Blockaid septal occluder, whose formally untested design and configuration could have led to its migration. We propose the need for strict guidelines for the selection of patients, and in this case, the choice of device, as well. The deficient aortic rim should not be ignored as it may predispose to device instability and embolization, in a fraction of the cases.
In conclusion, strict selection criteria governing an ‘adequate’ aortic rim, the size of the device, and the choice of the device may help reduce the incidence of complications like the rare, but potentially-fatal embolization of the device into the pulmonary artery following percutaneous device closure of an ASD. The cardiac surgeon will face an increasing number of such device-related complications, unless device closure of ASD is offered to a selected group of patients.
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Abstract
1. Introduction
