Stereotactic endovascular aortic navigation with a novel ultrasonic-based three-dimensional localization system.

BACKGROUND: Endovascular aortic procedures have been developed to treat many aortic diseases effectively. However, these procedures are also becoming increasingly complex given the development of branched or fenestrated endografts. Part of the difficulty lies in the limitations of current imaging paradigms. A more intuitive, three-dimensional (3D) mode of intraoperative imaging is desirable to accommodate the future progression of endovascular techniques. This article describes a novel endovascular catheter tracking device that uses ultrasonic signals, not ultrasound imaging. The tracking device displays real-time in vivo location on previously acquired 3D computed tomography (CT) images in an intuitive, endoluminal view. This system was tested in two swine and validated against fluoroscopy and by delivering stent grafts. METHODS: The ultrasonic-based localization system (ULS) provides real-time location information of a modified endovascular catheter and displays this location on preoperative 3D CT images. The 9F endovascular catheter has a small ultrasonic transmitter attached to its tip to signal its location to the ULS. Subsequent endovascular deployment of an aortic stent was carried out using only the ULS to target the stent placement position in the aorta of Yorkshire swine. System accuracy was measured against concurrent angiography as well as to deployed stents in situ. RESULTS: We successfully displayed the endovascular catheter tip location in real time along the registered CT aortic images, providing virtual endoluminal tracking. The relative accuracy of the ULS as compared with angiography for catheter movements in the abdominal aorta was found to have a mean error less than 1 mm. The ULS coordinates tracked within the lumen of the aortic image 98% of the time, as defined by the proportion of points within one radius distance of the aortic image centerline. Finally, three aortic stents were deployed using the ULS virtual image display to locate the target position in the aorta for stent deployment. Errors between target position and actual stent position ranged from -5.0 to +7.9 mm. CONCLUSIONS: This study demonstrates the feasibility of virtual image-guided endovascular aortic navigation using a ULS. This provides a 3D platform for virtual navigation on preoperative CT scan images during endovascular procedures that could assist in stent deployment as well as minimize or eliminate the need for procedural ionizing radiation and iodinated contrast. Future work will focus on miniaturization and refinements in accuracy that will be required to translate this technology into clinical application in endovascular procedures.

A prospective study of carbon dioxide digital subtraction versus standard contrast arteriography in the detection of endoleaks in endovascular abdominal aortic aneurysm repairs.

BACKGROUND: The objective of this study is to compare intraoperative endoleak detection by carbon dioxide digital subtraction angiography (CO(2)-DSA) during endovascular aortic aneurysm repair (EVAR) with standard iodinated contrast angiography (ICA). METHODS: Between 2006 and 2010, 76 patients with abdominal aortic aneurysms undergoing EVAR were enrolled in a prospective study. After EVAR, both an ICA and CO(2)-DSA completion study were performed. Two blinded vascular surgeons who were not involved with the EVAR separately interpreted the ICA and CO(2)-DSA results for the presence or absence of an endoleak. Identified endoleaks were classified by types. A third, "tie-breaker" blinded observer was used to resolve differences in interpretations. The sensitivity, specificity, negative predictive value, and positive predictive value were calculated for the ability of CO(2)-DSA to detect endoleaks. Cohen's κ statistic was used to assess interobserver agreement between the 2 initial interpreting surgeons. RESULTS: Of the 76 patients undergoing EVAR, 66 were men with average age of 76 years, a mean aneurysm size of 5.8 cm (range, 4-10 cm), and creatinine of 1 (standard deviation, 0.33). ICA identified 35 type I and 15 type II endoleaks, respectively, while CO(2)-DSA identified 40 type I and 10 type II endoleaks. Overall, CO(2)-DSA had a sensitivity of 0.84, specificity of 0.72, positive predictive value of 0.86, and negative predictive value of 0.69 of intraoperative endoleak detection, with respect to ICA as the criterion standard. The interobserver κ between surgeons for ICA was 0.56, for detection of any endoleak or type I endoleak with CO(2)-DSA was 0.58, and for detection of type II endoleak with CO(2)-DSA was 0.29. CONCLUSIONS: Interobserver agreement for the detection of endoleaks is superior with ICA compared to CO(2)-DSA. However, the sensitivity for detecting any endoleak and both the sensitivity and specificity for detecting type I endoleaks using CO(2)-DSA are acceptable. For detecting type II endoleaks using CO(2)-DSA, the sensitivity and positive predictive value are poor. Compared to ICA, CO(2)-DSA provides adequate images for endoleak detection during EVAR and is an acceptable alternative to ICA in patients at risk for contrast-related nephrotoxicity.

Safety of carbon dioxide digital subtraction angiography.

OBJECTIVE: Reports of fatality following carbon dioxide digital subtraction angiography (CO2-DSA) have raised concerns regarding its safety. This study reviews the safety of CO2-DSA. DESIGN: Single-institution retrospective review. SETTING: Tertiary care teaching hospital in Los Angeles, California. PATIENTS: A total of 951 patients who underwent 1007 CO2-DSA procedures during a 21-year period. MAIN OUTCOME MEASURES: Preprocedure and postprocedure creatinine values and periprocedural morbidity and mortality. RESULTS: A total of 632 arterial CO2-DSA were performed; 527 were aortograms with or without extremity runoff; 100, extremity alone; and 5, pulmonary. Venous CO2-DSA included 187 inferior vena cavagrams, 182 hepatic or visceral, 5 extremity venograms, and 1 superior vena cavagram. Associated endovascular procedures were performed in 499 cases; 162 were arterial interventions including 62 endovascular aneurysm repairs, 53 visceral or renal percutaneous angioplasty with/without stent, 41 extremity percutaneous angioplasty with or without a stent, and 4 cases of thrombolysis or embolization; 176 caval filters, 98 transjugular intrahepatic portosystemic shunts, 54 transjugular liver biopsies, and 9 other venous interventions. The mean preprocedure creatinine level was 2.1 mg/dL; postprocedure, 2.1 mg/dL (P = .56). There were a total of 61 (6.1%) procedural complications including 4 (0.4%) mortalities. Two were procedure-related complications: 1, suppurative pancreatitis following aortogram; and 2, hepatic bleed following failed transjugular intrahepatic portosystemic shunts. Two were attributable to patient disease; 1, metastatic adenocarcinoma; and 2, refractory, end-stage cardiomyopathy. CONCLUSION: Carbon dioxide digital subtraction angiography is a versatile technique that can be safely used for diagnostic and therapeutic endovascular procedures. Morbidity and mortality are acceptable with preservation of renal function. Thus, CO2-DSA is a safe alternative to iodinated contrast.

Symptomatic 7-cm abdominal aortic aneurysm in an otherwise healthy 31-year-old woman.

Abdominal aortic aneurysms are rare in young women. We report the case of a 31-year-old woman who underwent open surgical repair of a symptomatic 7-cm abdominal aortic aneurysm (AAA). The patient had no identifiable AAA risk factors. Laboratory and pathological analyses demonstrated a nonspecific inflammatory component.