Electrocardiography.

Continuous ECG monitoring should be used in all patients with congenital heart disease admitted to the cardiac intensive care unit (CICU). A standard three-electrode system with leads on the right arm, left arm, and left leg (right and left shoulder and left abdomen in neonates) can provide a single-lead (lead I, II, or III) continuous ECG tracing that accurately detects changes in the heart rate and rhythm along with ischemic changes. Continuous monitoring of the ECG tracing can also be utilized in the early detection of electrolyte disturbances, including potassium and calcium.

Noninvasive Blood Pressure Monitoring.

An occlusive cuff around the arm and leg of a preoperative neonate is an essential noninvasive monitoring device. In neonates, an appropriately sized cuff on the upper arm and calf may be used to monitor arm and calf pressures; these should be essentially identical. Noninvasive blood pressure measurements can be made by auscultatory methods or by the use of automated cuffs that use oscillometric methods. It should be noted that oscillometric automated cuffs measure systolic and mean arterial blood pressures directly and calculate the diastolic blood pressure. Thus interpretation of the diastolic blood pressure calculated by these automated cuffs should be interpreted with this in mind, particularly in with patients where there is diastolic runoff into the pulmonary artery via a patent arterial duct.

Indwelling Vascular Catheters.

One of the main advantages of an indwelling vascular catheter is the monitoring of pressure in an arterial or venous vascular structure. Pressure monitoring requires the introduction of an end-hole catheter into the vessel to be interrogated. Expert technical skill is necessary to place these catheters in preoperative neonates to avoid injury to vascular structures. Such catheters are commonly inserted into the umbilical vein, femoral vein, jugular vein, umbilical artery, femoral artery, or radial artery. Once placed, the catheter is connected to a pressure transducer via a coupling system that is subsequently connected to the monitor. Coupling systems contain tubing filled with a saline solution and a port for zeroing the catheter to atmospheric pressure and withdrawing blood samples. Modern transducers contain silicon crystals that change resistance in proportion to the changes in pressure from the coupling system’s fluid. These systems must be properly calibrated for the accurate assessment of intravascular pressures.

The pressure waveforms themselves are valuable sources of data. In arterial tracings, the slope of the upstroke can be used to generally assess contractility. A steep upstroke indicates adequate cardiac contractility, whereas a blunted upstroke may indicate poor contractility, aortic valve disease, or peripheral vasoconstriction from vasoactive drugs. The position of the dicrotic notch of the ventricular end-systolic pressure is an important indicator of peripheral vascular resistance. A low notch indicates low systemic vascular resistance (SVR) and can be a useful clinical indicator in a neonate with a patent arterial duct. Significant respiratory variation in the arterial waveform may indicate hypovolemia. Finally, one of the most important indications for placement of an invasive arterial catheter is the need for accurate assessment of the pulse width. A wide pulse width in the preoperative neonate is an important indicator of diastolic runoff into the pulmonary circulation and may be an early indicator of inadequate systemic blood flow. The reliability of these invasive data is improved by the use of a central arterial catheter as opposed to the noninvasive assessment of blood pressure.

Another advantage of an indwelling catheter is the ability to draw blood samples for serial laboratory monitoring. This is particularly useful for patients in whom there is concern for an evolving deficiency in DO ₂ . For example, the development of a metabolic acidosis or a rise in serum lactate levels may be an early indicator of inadequate DO ₂ . In neonates requiring diuretic therapy, an indwelling catheter allows for the daily assessment of serum electrolytes and safer intravenous replacement of any derangements. Indwelling central venous catheters also allow for the administration of parenteral nutrition.

Peripheral Vascular Line.

It is important to consider that the majority of preoperative neonates with a fUVH may be managed adequately with a peripheral intravenous line rather than an indwelling central venous catheter. The peripheral catheter can be used to administer infusions of PGE ₁ and low-concentration glucose. Peripheral intravenous catheters carry low insertion complication rates and minimize the risk for thromboembolism, vascular occlusion, and infection complications.

Pulse Oximetry.

Continuous pulse oximetry is utilized in all neonates with a fUVH. The probe is often placed on the distal extremity. In patients with fUVH with anatomic obstruction to systemic blood flow (see Chapter 69 ), a “preductal” and “postductal” saturation measurement is typically monitored by a probe on the right hand and either foot.

Near Infrared Spectroscopy.

A near infrared spectroscopy (NIRS) probe is used in many centers as a surrogate measure of the adequacy of DO ₂ . The probe is attached with a noninvasive self-adhesive pad applied to the forehead, abdomen, and/or lumbar area. It emits light in the near infrared spectrum, which is then measured by sensors at specific distances from the light source. Oxyhemoglobin and deoxyhemoglobin have unique peak absorption in the near infrared spectrum. Total hemoglobin concentration is measured by the absorbance of light at 800 nm. Analogous to the calculation of systemic saturation by the pulse oximeter, the NIRS monitor reports the ratio of oxyhemoglobin to total hemoglobin concentration. This value is often used as a surrogate for “mixed venous” oxygen saturation. Commercially available NIRS devices use proprietary algorithms to subtract oxygen saturation from overlying tissue such as bone. It is also important to note that NIRS does not distinguish between arterial and venous blood. Owing to these limitations, the NIRS monitor is used primarily as an adjunct to other indicators of cardiac output.

Novel Noninvasive Algorithms Based on High-Fidelity Continuous Physiologic Data.

Increasing numbers of centers now employ solutions to linearly display high-fidelity continuous physiologic data at the patient’s bedside. These systems are capable of presenting in a single longitudinal view any continuous physiologic data stream connected to the bedside monitor. Continuous data inputs include heart rate, respiratory rate, arterial and venous pressures, pulse oximetry, temperature, ventilator data, and medication infusion data. These data are typically displayed at 5-second intervals. Modern systems are also capable of overlaying serial pertinent laboratory data (including blood gas and lactate levels) on the physiologic data streams. Longitudinal displays can be used to quickly visualize important clinical trends in pre- versus postductal oxygen saturations, blood pressures, and pulse width.

Continuous data streams have recently been used to develop complex mathematical algorithms to detect the risk for inadequate DO ₂ . One such algorithm, the iDO ₂ index, approved by the US Food and Drug Administration, uses physiologic data streams to display the probability of the mixed venous saturation below 40% and thus inadequate DO ₂ . This algorithm was validated in a large cohort of neonates with a fUVH and a multidistribution circulation. A sustained period with an iDO ₂ index below 40% has been associated with an increased incidence of cardiac arrest and a protracted stay in the CICU.

Electroencephalography.

Continuous EEG monitoring may provide information on cortical brain activity. In standard EEG monitoring, leads are placed over regions of the skull, and a cart with a CPU and video camera is placed at the foot of the bed. Changes in the electrical tracings are correlated with abnormal movements or changes in vital signs. Preoperative EEG monitoring is not routinely undertaken in most centers unless there is specific concern for a structural brain abnormality, genetic syndrome, or clinical seizure.

Role of Positive-Pressure Ventilation in the Neonate With a Multidistribution Circulation and Shock.

Noninvasive and invasive positive airway pressure may be used to recruit lung volume and improve oxygenation (continuous positive airway pressure and positive end-expiratory pressure, respectively) and provide ventilatory assistance (bilevel positive airway pressure [BiPAP] and tidal volume ventilation, respectively). In addition, mechanical ventilation unloads the respiratory pump, allowing for the redistribution of a limited Qs to other vital organs. Under normal conditions, respiratory muscle VO ₂ is a small fraction of global VO ₂ . Accordingly, the respiratory pump receives less than 5% of total CO. However, as respiratory work increases—due to metabolic acidosis–induced hyperventilation, for example, or impaired respiratory mechanics—respiratory muscle VO ₂ may approach 40% to 50% of total body VO ₂ . When this occurs and CO is limited, respiratory pump perfusion may occur at the expense of other vital organs, including the brain. Also, in the neonate with an increased minute ventilation and work of breathing, by eliminating exaggerated negative intrathoracic pressure (ITP) and increasing ITP above atmospheric with positive-pressure ventilation (PPV), afterload for the systemic ventricle decreases significantly (ventricular systolic transmural pressure decreases). The net effect of these changes is a marked improvement in the respiratory, myocardial, and global VO ₂ -DO ₂ relationship. In summary, intubation and PPV is helpful in neonates—usually with a postnatal diagnosis—who present with low systemic blood flow and/or circulatory collapse, whereas “elective” PPV (1) is usually not indicated and (2) can increase surgical risk and contribute to hospital morbidity (see earlier).

Decision Making.

In the patient with duct-dependent pulmonary blood flow, creation of a reliable source of flow is generally performed within the first week of life. Classically a thoracotomy is performed on the side opposite arch dominance and an ePTFE graft is used to create a shunt between the innominate artery and the ipsilateral proximal pulmonary artery. This approach results in a primary median sternotomy incision for the next-stage operation, but the disadvantage is that the duct cannot be controlled or ligated at the completion of the procedure. Having both a patent arterial duct and a systemic-to-pulmonary artery shunt results in hypotension and low-velocity flow through the synthetic shunt, which predisposes to shunt thrombosis; however, this does not become apparent until the duct begins to close. In the current era a median sternotomy incision is commonly used for shunt construction. There are several advantages to a median sternotomy. The duct can be ligated after construction of the shunt and the adequacy of the shunt can therefore be determined. The innominate artery and the proximal branch pulmonary artery are more easily accessed. If necessary, cardiopulmonary bypass support can be used for construction of the shunt if the patient does not tolerate branch pulmonary artery occlusion. Patch arterioplasty is necessary for proximal branch pulmonary artery stenosis in the region of duct insertion.

Surgical Technique.

Thoracotomy: The patient is placed in the lateral decubitus position and a posterolateral thoracotomy incision is made on the side opposite the aortic arch through the fourth interspace. An incision is made in the mediastinal pleura posterior to the superior caval vein, and the pulmonary and innominate arteries are identified. Lymph nodes along the side of the trachea are resected and the pulmonary artery is dissected as far medially as possible. The innominate artery is fully mobilized. Heparin is administered, typically, 100 units/kg, and the innominate artery is isolated. A longitudinal incision is made in the inferior surface of the innominate artery. A 3.5- or 4.0-mm graft is commonly used. The graft is cut in a beveled fashion to accommodate the angle of the innominate artery and an anastomosis is constructed with fine monofilament suture. An alternative approach is to perform the proximal anastomosis to the subclavian artery. The use of the smaller subclavian artery as the origin of the shunt will add resistance to shunt and allows for larger-caliber graft to be used; it may also be useful in the smaller patient to accommodate a normal-caliber graft. Once the proximal anastomosis is complete, the graft is cut to the appropriate length to reach the pulmonary artery. The innominate artery is de-aired, flow is restored, and the graft is controlled with a fine vascular clamp. After isolating the pulmonary artery, a longitudinal arteriotomy is made in the pulmonary artery and the distal anastomosis is performed. Clamps and snares are removed from the pulmonary artery and the shunt is opened. There should be a drop in blood pressure corresponding to flow in the shunt with an increase in pulmonary artery saturations. Prostaglandin infusion is halted.

Sternotomy: The patient is placed in the supine position and a median sternotomy incision is performed. After exposing the heart, the innominate artery is mobilized. The proximal ipsilateral pulmonary artery is likewise exposed. It may be possible to encircle the duct at this point, but care should be taken, as this may not be tolerated because it can result in excessive hypoxemia; in addition, the duct can be bruised or injured, and this would also compromise pulmonary blood flow. The shunt is constructed the same as for a thoracotomy approach. Following completion of the shunt and after it has been opened, the duct can be encircled and snared to make certain that there will be adequate pulmonary blood flow with the newly constructed shunt. If the saturations remain satisfactory, the duct is ligated. If the patient develops excessive hypoxemia with snaring of the duct, a stepwise approach to determine the problem should be undertaken, including making certain that ventilation is adequate. The shunt should finally be inspected for technical issues. Revision of the shunt or replacement with larger graft should be considered if occlusion of the duct is not tolerated.

Decision Making.

Pulmonary artery banding is the first stage of palliation in neonates with unrestrictive pulmonary blood flow and no systemic outflow tract obstruction ( Fig. 71.3 ). Pulmonary artery banding relieves the volume load on the heart; otherwise heart failure may ensue. Pulmonary artery banding reduces pulmonary artery pressure, allowing for continued remodeling of the pulmonary vascular bed for subsequent second stage of palliation. Neonatal PVR reaches a nadir around the third or fourth week of life, and traditionally pulmonary artery band placement has been performed after 2 or 3 weeks of age. It has been thought that placing a pulmonary artery band in the early neonatal period may lead to the need to reoperate for band readjustment once the PVR falls. Recent data, however, suggest that delay is not necessary, and that pulmonary artery banding can be performed during the first week or two of life.

Construction of a pulmonary artery band (PAB). Ao, Aorta; PA, pulmonary artery.

(From Tweddell JS. Principles and practice of pediatric surgery. In: Oldham KT, Colombani PM, Foglia RP, et al, eds. Annals of Surgery . Philadelphia: Lippincott Williams & Wilkins; 2006:1804.)

Ligation of the main pulmonary artery and placement of a systemic-to-pulmonary artery shunt has been advocated by some as a strategy to manage the patient with unrestricted pulmonary blood flow. The theoretical advantage is the ability to more precisely control pulmonary blood flow. This is uncommonly used in practice due the increased risk of systemic-to-pulmonary artery shunt compared with pulmonary artery banding.

Pulmonary artery banding can be performed through a thoracotomy or median sternotomy incision. If the arterial duct is patent or there is any question of patency, the duct is ligated. The main pulmonary artery can be banded with a variety of material including ePTFE, polyester tape, or silk. The aorta is separated from the pulmonary artery and the tape passed around the main pulmonary artery. The length of band can be estimated according to the Trusler rule. The length of the band should be 20 mm plus the number of millimeters corresponding to the child’s weight in kilograms. Neonates with transposition physiology will be more cyanotic due to unfavorable streaming. In this case the length should be 24 mm plus the child’s weight to prevent excessive hypoxemia. Arterial saturation and pressure in the distal pulmonary artery should be monitored during banding. The patient should be placed on an FiO ₂ of 50% to decrease the amount of dissolved oxygen. The band should be adjusted to achieve a distal pulmonary artery pressure of 15 to 20 mm Hg or one-fourth of the systolic blood pressure. The saturation should be 80% to 85%. A common technique is to use hemoclips to make the final adjustments. This allows the band to be tightened and loosened in 1-mm increments. The final adjustment is commonly a compromise between achieving a satisfactory pressure and avoiding excessive hypoxemia. Once the proper tightness is achieved, the band is secured with multiple sutures between the band and the pulmonary artery. Ideally the band should be above the sinotubular junction of the pulmonary valve and not impinging on the origin of either pulmonary artery. If it is not properly secured, the band can slip and compromise the origin of a pulmonary artery, typically the right pulmonary artery, and result in excessive hypoxemia. If the band is positioned too far proximally, it can encroach on the pulmonary valve and result in leaflet damage, which can cause regurgitation.

Decision Making.

For isolated coarctation with or without arch hypoplasia and without additional left ventricular outflow tract obstruction (aortic valvar or subaortic stenosis), standard coarctation repair can be performed (see also Chapter 45 ). If the arch hypoplasia is distal to the origin of the left carotid artery, the arch can be approached via a left thoracotomy. If there is proximal arch hypoplasia, an approach via a median sternotomy using cardiopulmonary bypass will be necessary. The procedure can be combined with pulmonary artery banding.

In certain groups of fUVHs with a dominant left ventricle and discordant ventriculoarterial connections, the aorta can arise from a rudimentary outflow chamber or right ventricle and connect to the left ventricle via an interventricular communication. A restrictive interventricular communication will result in systemic outflow tract obstruction. When the interventricular communication is small at birth, aortic hypoplasia—frequently with coarctation and occasionally with an interrupted aortic arch—may be present. Even when the interventricular communication is nonrestrictive at birth, it can become narrow over time, resulting in obstruction, and the tendency for systemic outflow obstruction to progress after pulmonary artery banding has been well recognized. Strategies to prevent development of outflow tract obstruction or manage its presence include an anastomosis between the pulmonary root and the ascending aorta—the Damus-Kaye-Stansel (DKS) procedure simultaneously described by Paul Damus, Michael Kaye, and Horace Stansel in the 1970s ( Fig. 71.4 ). The anastomosis of the pulmonary root and aorta bypasses the restrictive interventricular communication. A direct approach at enlargement of the interventricular communication is challenging in the neonate and risks injury to the conduction system with resultant complete heart block.

Examples of the Damus-Kaye-Stansel (DKS) procedure for the relief of systemic outflow obstruction in the setting of a dominant left ventricle with transposed great vessels and the aorta (Ao) arising from the rudimentary right ventricle (rv, RV). (A) Diagram showing a DKS for tricuspid atresia with transposition. (B) DKS in a patient with double-inlet left ventricle with L-looped ventricles. LV, Left ventricle; PA, pulmonary artery; PT, Pulmonary trunk.

(A, From Yoo SJ, Caldarone CA. Glossary of paediatric cardiovascular surgical procedures. In: Yoo SJ, Babyn P, MacDonald C, eds. Chest Radiographic Interpretation in Pediatric Cardiac Patients . New York: Thieme; 2010:41–54. B, From Gates RN, Laks H, Elami A, et al. Damus-Stansel-Kaye procedure: current indications and results. Ann Thorac Surg. 1993;56:111–119.)

A DKS procedure requires cardiopulmonary bypass; therefore coarctation repair with pulmonary artery banding offers the newborn a less morbid procedure. In the current era, where a bidirectional superior cavopulmonary anastomosis is generally performed during infancy, an interventricular communication area greater than 1 to 2 cm ² /m ² (corresponding to a interventricular communication diameter of 7 mm or greater) is a reasonable cutoff identifying those patients who are unlikely to develop obstruction during infancy prior to a superior cavopulmonary anastomosis. In these patients, arch repair and pulmonary artery banding can be considered for neonatal palliation and a more definitive procedure to prevent systemic ventricular outflow obstruction can be part of the second-stage palliation.

More severe forms of systemic ventricular outflow tract obstruction are frequently associated with coarctation and arch hypoplasia. This includes more severe forms of fUVH with a dominant left ventricle and discordant ventriculoarterial connection (tricuspid atresia with transposed great vessels), and those with dominant right ventricle and concordant ventriculoarterial concordant connections (e.g., hypoplastic left heart syndrome). For these neonates there are two surgical options, Norwood palliation and so called “hybrid palliation.”

The Norwood procedure includes arch reconstruction, a DKS type root amalgamation, creation of a nonrestrictive atrial septal defect, and placement of an appropriately restrictive source of pulmonary blood flow—either a modified Blalock-Taussig shunt or a shunt from the right ventricle to the pulmonary artery ( Fig. 71.5 ). The Norwood procedure requires cardiopulmonary bypass with a period of aortic cross-clamping and perfusion techniques that allow for aortic arch reconstruction. This remains one of the higher-risk procedures commonly performed in the newborn period.

(A) Norwood procedure with a systemic-to-pulmonary artery (Blalock-Taussig) shunt. (B) Norwood procedure with a conduit from the right ventricle (RV) to the pulmonary artery (PA). Ao, Aorta; IVC, inferior vena cava; LPA, left pulmonary artery; PV, pulmonary vein; SVC, superior vena cava; TV, tricuspid valve.

(From Barron DJ, Brooks A, Stickly J, et al. The Norwood procedure using a right ventricle–pulmonary artery conduit: comparison of the right-sided versus left-sided conduit position. J Thorac Cardiovasc Surg . 2009;138[3]:528–537.)

The hybrid procedure is an alternative that provides for neonatal palliation including banding of the branch pulmonary arteries and maintenance of the arterial duct with either a stent or a prostaglandin infusion ( Fig. 71.6 ). If not present, a nonrestrictive atrial septal defect is created using interventional catheter-based techniques. The advantage of the hybrid procedure is that is does not use cardiopulmonary bypass. Definitive management of left ventricular outflow tract obstruction and arch hypoplasia involves a Norwood-style reconstruction combined with the second-stage procedure. Some programs use the hybrid procedure for all neonates with fUVH and severe arch hypoplasia. This avoids a long period of cardiopulmonary bypass in the vulnerable neonate. Other programs reserve this alternate strategy for patients with risk factors for cardiopulmonary bypass including; prematurity, low birth weight, infection, necrotizing enterocolitis, and intracranial hemorrhage. The disadvantage of the hybrid procedure is a more challenging period between neonatal palliation and the comprehensive second-stage procedure, including the predictable need for catheter-based reintervention directed at the atrial septum or narrowing between the stented arterial duct and the more proximal aortic arch, referred to as retrograde arch obstruction. In addition, the second-stage procedure is more complicated and requires a long period of cardiopulmonary bypass for arch reconstruction and reconstruction of the banded pulmonary arteries. At present the decision between the Norwood procedure and the hybrid approach remains largely program-specific without an obvious advantage to either procedure in the average-risk neonate.

The hybrid procedure combines banding of the branch pulmonary artery and maintenance of the arterial duct. This can be accomplished with a prostaglandin infusion for short-term patency or with a stent. In addition, a nonrestrictive atrial septal communication must be created.

(From Barron DJ, Kilby MD, Davies B, et al. Hypoplastic left heart syndrome. Lancet . 2009;374[9689]:551–564.)

Surgical Technique.

The DKS is performed through a median sternotomy incision using cardiopulmonary bypass. Patients suitable for an isolated DKS do not have arch obstruction, and profound hypothermia is not necessary. After cross-clamping and cardioplegia, an anastomosis—generally with patch augmentation—is made between the great vessels above the sinotubular junction of the semilunar valves. There are two general techniques. In the first the pulmonary root is transected above the sinotubular junction and a vertical incision is made in the ascending aorta adjacent to the pulmonary root. The adjacent proximal edges of the aorta and pulmonary root are joined, and the remainder of the connection is accomplished with a patch. The second technique, sometimes called the “double-barreled” technique, involves complete transection of both great vessels above the sinotubular junction. The great vessels are joined at their “kissing” point and the ascending aorta is then anastomosed to this double-barreled root. Patch augmentation is frequently required to make for the size discrepancy between the combined root and the ascending aorta. A source of pulmonary blood flow is necessary. In the neonate with a single left ventricle, this will be a systemic-to-pulmonary artery shunt. In an infant that was suitably palliated with a pulmonary artery band, a bidirectional superior cavopulmonary anastomosis can be performed.

The Norwood procedure (Video 71.1 ) is performed through a median sternotomy with cardiopulmonary bypass. After initial dissection, the patient is cannulated for cardiopulmonary bypass. Arterial cannulation is achieved by cannulating either the pulmonary artery, arterial duct, or using an ePTFE graft anastomosed to the innominate artery. Single venous or bicaval cannulation can be used for venous return. Once cardiopulmonary bypass has been established, flow to the pulmonary arteries is prevented by snaring either the branch pulmonary arteries or the ductus arteriosus. Three perfusion strategies have been described for the period of arch reconstruction; deep hypothermic circulatory arrest at 18°C, antegrade cerebral perfusion at deep hypothermia at 18°C to 22°C, or continuous perfusion at moderate hypothermia. The last approach requires placement of an additional arterial cannula to supply flow to the descending thoracic and abdominal aorta during arch reconstruction. The site of distal cannulation can include cannulation of the arterial duct, descending thoracic aorta at the level of the diaphragm, or femoral artery.

During a period of aortic cross-clamping and altered perfusion, arch reconstruction including amalgamation of the aortic and pulmonary roots is accomplished ( Fig. 71.7 ). A nonrestrictive atrial septal defect is created. The cross clamp is released and rewarming completed. Finally a source of pulmonary blood flow is established—either a systemic-to-pulmonary artery shunt or a right ventricle-to-pulmonary artery conduit. Once rewarming has been completed and cardiac function has returned, vasoactive support is initiated. Commonly milrinone and catecholamines are used. Prior to weaning from bypass, the patient should be in an AV sequential rhythm, hematocrit should be at least 35%, ionized calcium should be within the normal range, and the systemic vascular resistance should be about 12 Woods units. The SVR can be estimated by dividing the mean arterial pressure by the cardiac index. Further adjustments of vasoactive agents are made to achieve the target SVR. For the patient with a systemic-to-pulmonary artery shunt, the shunt is opened as the cardiopulmonary bypass flow is reduced. After successful weaning from bypass, modified ultrafiltration can be performed. Evaluation of the procedure is then undertaken. This can include echocardiography, either epicardial or transesophageal, to evaluate function, the adequacy of the atrial septal defect, and the degree of tricuspid valve regurgitation. Regional perfusion as assessed by NIRS should be used to assess DO ₂ . Residual systemic outflow obstruction can be ruled out by comparing the systemic ventricular systolic pressure with a pressure measured from the femoral or umbilical artery catheter. Once the clinician is satisfied with the repair, the venous cannula is removed and protamine is administered to reverse anticoagulation. The arterial cannula can be left in place until after protamine has been administered. It is essential to achieve complete hemostasis. Transfusion of platelets and fibrinogen—either fresh frozen plasma or cryoprecipitate—is common. Careful inspection of the surgical sites should be undertaken and additional sutures placed as necessary. For continued bleeding that does not seem to be surgical and has not responded to component transfusion, additional agents such recombinant factor VIIa or prothrombin complex concentrates can be considered.

Technique of Norwood arch reconstruction. (A) After cooling on cardiopulmonary bypass to 18°C, cardioplegic arrest is achieved and antegrade cerebral perfusion established. The aortic isthmus is divided, and all the ductal tissue is resected (inset) . The extent of resection of ductal tissue is determined by identifying the change in thickness of the vessel, as the ductus is slightly thicker-walled than the aorta. In addition, the intercostal vessels arise from the aorta and the ductal tissue ends a few millimeters away from the first set of intercostal vessels. (B) After mobilizing the descending thoracic aorta, which requires division of the first two or three sets of intercostal vessels, an incision is made in the aorta from the open end of the aortic isthmus to the level of the pulmonary root. A cutback is made in the posterior aspect of the descending thoracic aorta. The cutback incision is directed toward the origin of the intercostal vessels. (C) An interdigitating arch reconstruction is created. The descending thoracic aorta is advanced as far as the distal ascending aorta. A large suture line from native tissue to native tissue is created. A patch of porcine small intestinal submucosa is fashioned as a quarter circle with a radius of 3.5 cm (inset) . The patch is used to augment the arch and ascending aorta and complete the connection of the aorta and pulmonary root. The patch is aligned beginning at the white arrow . The straight edge, indicated by the black arrow , is sutured to the inner curvature, and the curved edge, indicated by the gray arrow , is sutured to the outer curvature. The aortic root is joined to the pulmonary root in an incision in the pulmonary root just leftward of the commissure adjacent to the ascending aorta. (D) The patch is being sewn into place. (E) Excess patch is trimmed (not shown) and the proximal suture line completed.

(From Jacobsen RM, Mitchell ME, Woods RK, et al. Porcine small intestinal submucosa may be a suitable material for Norwood Arch reconstruction. Ann Thorac Surg . 2018;106[6]:1847–1852.)

Once hemostasis has been achieved, the decision to close versus leaving the sternum open is made. For those patients who have had a long bypass run and are on more than the usual inotropic support, delayed sternal closure may be necessary. Although some programs routinely leave the sternum open, there is little question that this prolongs the length of time to extubation and, as a consequence, also CICU length of stay and hospitalization. Therefore it seems reasonable to determine whether the sternum can be closed primarily. Sternal closure sutures are placed and the sternum reapproximated. The hemodynamics are evaluated and if there is no perturbation, sternal closure can be completed and the remainder of the incision closed in the usual manner. If sternal approximation results in important hypotension and/or desaturation or if there is evidence of decreased systemic DO ₂ as assessed by NIRS or venous saturation, the sternum should be left open. Once the patient begins to diurese and vasoactive support can be weaned, chest closure can be performed. If the patient fails to progress, residual lesions should be ruled out.

The hybrid approach is defined by placement of individual branch pulmonary artery bands. Ductal patency is maintained with either a stent or prostaglandin. In addition, catheter-based creation of a nonrestrictive atrial septal defect is necessary if this is not already present. Typically the procedure is performed in a hybrid catheterization laboratory. A median sternotomy is performed. Branch pulmonary artery banding is performed first. Rings 2 to 3 mm in diameter are cut from an ePTFE tube graft that is 3.0 or 3.5 mm in diameter. With the typical hypoplastic left heart syndrome anatomy, the left pulmonary artery is banded first, as it is the most difficult to access. The right pulmonary artery is banded next. The adequacy of the banding can be directly measured by catheter and additional fine adjustments can be made. If a stent is to be placed to maintain duct patency, this is performed last. The atrial septal defect can then be enlarged using catheter-based techniques.