After the operations for single ventricle defects, the heart functions like a one-sided pump with two chambers. The heart no longer receives deoxygenated blood from the veins. Instead, this blood flows directly to the lungs. The heart receives oxygenated blood from the lungs and pumps it to the body. This is called Fontan circulation. This operation will occur within several days of birth. Depending on the type of heart defect, different surgical procedures may be used, including the Norwood procedure.
The purpose of this operation is to ensure that blood-flow is controlled enough to prevent damage to the heart and lungs, and that enough blood is reaching the lungs to keep the child alive until the second operation. Called the hemi-Fontan or Glenn operation, the second procedure usually occurs within six months of birth.
After this operation, deoxygenated blood from the upper body goes to the lungs without passing through the heart. During this surgery the inferior vena cava, a large vein that carries deoxygenated blood from the lower body into the heart, is disconnected from the heart and attached to the pulmonary artery.
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After this operation, all of the deoxygenated blood from the body goes to the lungs without passing through the heart. Frequent surveillance in infancy and early childhood is important to minimize risk factors for the eventual Fontan operation. The patient will require a number of imaging procedures in order to determine the individual anatomy of the great arteries and, most importantly, the coronary arteries.
The coronary arteries are carefully mapped out in order to avoid unexpected intra-operative complications in transferring them from the native aorta to the neo-aorta. As with any procedure requiring general anaesthesia, arterial switch recipients will need to fast for several hours prior to the surgery to avoid the risk of aspiration of vomitus during the induction of anesthesia.
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As the patient is anesthetized, they may receive the following drugs , which continue as necessary throughout the procedure:. The heart is accessed via median sternotomy , and the patient is given heparin to prevent the blood from clotting. A generous section of pericardium is harvested , then disinfected and sterilized with a weak solution of glutaraldehyde ; and the coronary and great artery anatomy are examined. The ductus arteriosus and right pulmonary branch , up to and including the first branches in the hilum of the right lung , are separated from the surrounding supportive tissue to allow mobility of the vessels.
Silk marking sutures may be placed in the pulmonary trunk at this time, to indicate the commissure of the aorta to the neo-aorta ; alternatively, this may be done later in the procedure.
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The cardiopulmonary bypass is then initiated by inserting a cannula into the ascending aorta as distally from the aortic root as possible while still supplying all arterial branches, another cannula is inserted into the right atrium , and a vent is created for the left ventricle via catheterization of the right superior pulmonary vein. While the patient is cooling, the ductus arteriosus is ligated at both the aortic and pulmonary ostia , then transected at its center; the left pulmonary branch , including the first branches in the hilum of the left lung, is separated from the supportive tissue; and the aorta is marked at the site it will be transected, which is just below the pulmonary bifurcation , proximal to where the pulmonary artery will be transected.
When the patient is fully cooled, the ascending aorta is clamped as close as possible below the HLM cannula, and cryocardioplegia is achieved by delivering cold blood to the heart via the ascending aorta below the cross clamp. The aorta is then transected at the marked spot, and the pulmonary artery is transected a few millimetres below the bifurcation. The vessels are again examined, and the pulmonary root is inspected for left ventricular outflow tract obstruction LVOTO.
If a ventricular septal defect VSD is present, it may be repaired, at this point via either the aortic or pulmonary valve ; it may alternatively be repaired later in the procedure.
powerbadges.com/gurob-samsung-galaxy-s5.php The great arteries are usually arranged using the LeCompte maneuver , with the aortic cross clamp positioned to hold the pulmonary artery anterior to the ascending aorta; though with some congenital arrangements of the great arteries, such as side-by-side, this is not possible and the arteries will be transplanted in the non-anatomic 'anterior aorta' arrangement.
If the aortic commissure has not yet been marked, it may be done at this point, using the same method as would be used prior to bypass; however, there is a third opportunity for this still later in the procedure. Coronary arteries are examined closely, and the ostia and proximal arterial course are identified, as are any infundibular branches, if they exist. The coronary ostia and a large "button" of surrounding aortic wall are then excised from the aorta, well into the sinus of Valsalva ; and the proximal sections of the coronary arteries are separated from the surface of the heart, which prevents tension or distortion after anastomosis to the neo-aorta.
Infundibular branches are sometimes unable to be spared, but this is a very rare occurrence. If the aortic commissure has not previously been marked, the excised coronary arteries will be used to determine the implantation position of the aorta.
The aorta is then transplanted onto the pulmonary root, using either absorbable or permanent continuous suture. The aortic clamp is temporarily removed while small sections of the neo-aorta are cut away to accommodate the coronary ostia, and a continuous absorbable suture is then used to anastomose each coronary "button" into the prepared space. In most cases, the coronary implantation sites will be at left and right anterior positions at the base of the neo-aorta; however, if the circumflex coronary artery branches from the right coronary artery , the circumflex coronary artery will be distorted if the pair are not implanted higher than normal on the neo-aorta, and in some cases they may need to be implanted above the aortic commissure, on the native aorta itself.
Stage 1: Norwood procedure
The circumflex coronary artery may originate from the same coronary sinus as, rather than directly from, the right coronary artery, in which case they may still be excised on the same "button" and transplanted similarly to if they had a shared ostium, unless one or both have intramural communication with another coronary vessel.
Sometimes, one or more coronary ostia are located very close to the valvular opening and a small portion of the native aortic valve must be removed when the coronary artery is excised, which causes a generally mild, and usually well- tolerated , neo-pulmonary valve regurgitation. The HLM is turned off and the aortic and atrial cannula are removed, then an incision is made in the right atrium, through which the congenital or palliative atrial septal defect ASD is repaired; where a Rashkind balloon atrial septostomy was used, the ASD should be able to be closed with sutures, but cases involving large congenital ASDs or Blalock-Hanlon atrial septectomy , a pericardial, xenograft , or Dacron patch may be necessary.
If there is a VSD which has not yet been repaired, this is performed via the atrial incision and tricuspid valve , using sutures for a small defect or a patch for a large defect. When the septal defects have been repaired and the atrial incision is closed, the previously removed cannula are replaced and the HLM is restarted.
The left ventricle is then vented and the cross clamp removed from the aorta, enabling full-flow to be re-established and rewarming to begin; at this point the patient will receive an additional dose of Regitine to keep blood pressure under control.
The previously harvested pericardium is then used to patch the coronary explantation sites, and to extend - and widen, if necessary - the neo-pulmonary root, which allows the pulmonary artery to be anastamosed without residual tension; the pulmonary artery is then transplanted to the neo-pulmonary root. The patient is fitted with chest tubes , temporary pacemaker leads, and ventilated before weaning from the HLM is begun. The rib cage is relaxed and the external surgical wound is bandaged, but the sternum and chest incision are left open to provide extra room in the pleural cavity , allowing the heart room to swell and preventing pressure caused by pleural effusion.
The sternum and chest can usually be closed within a few days; however, the chest tubes, pacemaker, ventilator, and drugs may still be required after this time. The patient will continue to fast for up to a few days, and breastmilk or infant formula can then be gradually introduced via nasogastric tube NG tube ; the primary goal after a successful arterial switch, and before hospital discharge, is for the infant to gain back the weight they have lost and continue to gain weight at a normal or near-normal rate.
Scottish pathologist Matthew Baillie first described TGA in , presumably as a posthumous diagnosis. In , American surgeons Alfred Blalock and C. Rollins Hanlon introduced the Blalock-Hanlon atrial septectomy , which was then routinely used to palliate patients.