SPY Imaging System: Its Role in Pediatric Cardiac Surgery

Overview

The current method of evaluating the surgical repair during surgery is limited to echocardiography (a noninvasive diagnostic procedure that uses ultrasound to study the structure and motions of the heart) or an invasive procedure called cardiac catheterization. The SPY imaging system makes use of the fluorescence properties of indocyanine green (ICG) to obtain high quality images in blood vessels. ICG is a green dye used to test heart output. The use of the SPY imaging system during surgery may provide valuable information regarding successful vessel connection and the area remaining unblocked. This study will compare the results of images to echocardiography and conventional angiography results. With SPY imaging, congenital heart surgeons would be able to check the quality of the procedure and revise, redo or perform additional procedures as dictated by the images before the patient leaves the operating room.

It would be advantageous to detect potential problems with vessel and anastomotic patency prior to leaving the operating room. The SPY imaging system makes use of the fluorescence properties of Indocyanine Green (ICG) to obtain high quality images of blood vessels. Unlike conventional angiography, indocyanine green fluorescence imaging offers the potential for a reliable, non invasive, inexpensive and rapid method of intraoperative assessment of vessel and anastomotic patency. This type of imaging resource could be invaluable in a repair such as: 1. coronary artery re-implantation following arterial switch procedure for transposition of the great arteries, anomalous coronary artery from the pulmonary artery repair, or aortic root replacement, 2. coarctation of the aorta, 3. Blalock-Taussig shunt, right-ventricle-to-pulmonary artery shunt, or cavopulmonary connection for single ventricle palliation, and 4. branch or distal pulmonary artery reconstruction/unifocalization in tetralogy of Fallot and pulmonary atresia/ventricular septal defect. The SPY imaging system is feasible for a variety of congenital heart defects and can provide valuable information regarding vessel and anastomotic patency. Specific Aim 1: Evaluate quality of images for clarity and ability to visualize desired anatomic area Specific Aim 2: Compare results of images to echocardiography and conventional angiography results * Part 1. Compare the results of pre-repair intra-operative SPY images to preoperative echocardiography results, and cardiac catheterization results when available * Part 2. Compare the results of post-repair intraoperative SPY images to postoperative echocardiography results, and cardiac catheterization results when available Approximately 40 patients in total will be enrolled in the study - 10 who have undergone coronary reimplantation, 10 who have undergone repair of coarctation of the aorta, 10 who have undergone a palliative shunting procedure, and 10 who have undergone pulmonary artery reconstruction. Echocardiography: Preoperative, intraoperative, and postoperative cardiac catheterization reports will be analyzed. Cardiac catheterization: Preoperative and postoperative cardiac catheterization reports will be analyzed. SPY imaging: ICG green will be administered in the following doses: 1.25 mg in infants (\< 1 year), 2.5 mg in children (\<16 years), and 5 mg in adult size patients (17-18 years of age). Doses will be injected in 1 ml volumes directly into the aorta, right ventricle or pulmonary artery, depending upon the procedure. Repeat dosing and imaging may be performed if needed. The total dose of dye will be limited to 2 mg/kg. Images will be obtained in the operating room prior to commencing and after weaning from cardiopulmonary bypass.