**4.4 Special considerations**

Neonates with a restrictive atrial septum are usually quite ill-appearing with hypoxia and heart failure. The keys to management prior to cardiac catheterization intervention are intubation; ventilation; maintaining good blood volume; inotropic support in the form of a dopamine infusion or epinephrine infusion and continuing prostaglandin. It should be noted that increasing the PGE may worsen the clinical picture as there may be a transient increase in the blood return to the left atrium with no egress. Administration of sodium bicarbonate to mitigate the acidotic milieu and alerting the cardiac catheterization team as well as the surgical team are crucial. The atrial level communication in a patient with HLHS is superior in position and often times the tissue is very thick. As such, the cardiac catheterization intervention to establish atrial level patency can be challenging. If a balloon atrial septostomy cannot be effectively performed, then static ballooning may be done (alternatively stent implantation across the restrictive PFO) and if that fails, the surgical opening of the atrial septum is indicated. Blalock-Hanlon procedure (described in 1948 by Alfred Blalock and C. Rollins Hanlon) [33] is not usually performed for HLHS patients.

Infants with moderate-to-severe tricuspid valve insufficiency and/or poor right ventricular function from the very beginning pose an especially high degree of challenge for the cardiac intensive care physician. Some considerations in their management include ventilation; institution of diuretics; inotropic support; heart failure/ cardiac transplant evaluation and supportive care/palliation team care involvement.

The patient with HLHS and severe pulmonary venous obstruction will develop marked hypoxemia over time. This hypoxemia may progress after a period of apparent well-being. The goal for these patients until surgical intervention—is to intubate, provide hyper-ventilation, increase FiO2, and increase SVR using inotropic support. A severe degree of pulmonary venous obstruction is a surgical emergency and may require rescue via extracorporeal membrane oxygenation (ECMO).

## **4.5 Non-cardiac pre-op management**

Genetic evaluation should include chromosome microarray and whole-exome sequencing, if indicated. A screening renal and head ultrasound is also recommended. Feeding the patient with HLHS pre-operatively is also important. Those with relatively balanced circulations—should feed by mouth. For those in whom we may be concerned about their systemic circulation—total parenteral nutrition may be the judicious approach to avoid complications such as necrotizing enterocolitis [2].

#### **4.6 Post-operative management of the HLHS**

The post-operative management of the HLHS patient is dependent on which initial procedure is undertaken. In general, there are three first-stage palliation procedures—Norwood procedure with MBTT shunt; Norwood procedure with Sano shunt; and the Hybrid procedure as mentioned in the above section.

The initial management of patients with Norwood MBTT shunt revolves again around achieving that fine balance between pulmonary and systemic flows. If the shunt is relatively large, the patient may have too much pulmonary blood flow and all the maneuvers to limit those as described in the prior section may be instituted. If the shunt placed is long or narrow and relatively resistive and or patient has high pulmonary artery pressure or PVR, then one may find oneself in the situation where there is a need to increase the SVR (use of epinephrine, norepinephrine, vasopressin, calcium) to drive flow through the shunt; to administer volume; and, in extreme cases, to Administrator pulmonary vasodilators in the form of inhaled nitric oxide. These maneuvers are intended to be temporary as the infant's circulation adapts. The management of these patients post-operatively requires great skill and expertise. One also needs to ensure patency of the shunt by administering anticoagulation—usually in the form of heparin drip—which could later be transitioned to Enoxaparin or Aspirin or both. The regimen of anticoagulation is institution-dependent.

The patients who undergo the Norwood procedure and Sano modification are, in general, less cerebrally challenging to care for. Their cardiac output is highly dependent on pre-load and single ventricular function and less so on a potentially tenuous balance between Qp and Qs. Volume administration and inotropic support generally are sufficient.

Both procedures require judicious monitoring and aggressive treatment of dysrhythmias.

#### **4.7 Hybrid procedure**

The Hybrid procedure involves placement of a PDA stent and bilateral PA bands and, if needed, atrial septostomy [22, 23]. The management of patients post-operatively after a Hybrid procedure can be very similar to the way we manage patients post a Norwood procedure and MBTT shunt. Balancing Qp:Qs is important. Keen attention should be paid to the maintenance of duct patency with anticoagulation and/or anti-platelet therapies.

Patients should be observed closely for signs of stent migration either into the pulmonary artery or the aorta as well as for the possibility of PA band migration. Retrograde arch obstruction from the migration of the stent can be screened through daily 4-limb blood pressure measurements. Intermittent echocardiographic assessment can assist in early diagnosis.

#### **4.8 Second stage palliation**

The Glenn procedure is the second stage in the HLHS palliation. By far, it is much less challenging to manage these patients post-operatively. The expectation is that these patients will exit the operating room extubated. If the patient had a reassuring pre-Glenn catheterization study, then the hope is that this would have translated into a successful procedure.

In terms of the respiratory system, post-operative care lies in the avoidance of high positive end-expiratory pressure (PEEP) and high PVR states. Through avoidance

#### *Hypoplastic Left Heart Syndrome DOI: http://dx.doi.org/10.5772/intechopen.104723*

of hyperventilation, one may manipulate PaCO2 to optimize flow in the Glenn circulation should the patient be intubated. Augment cardiac inotropy, if necessary. Oftentimes, a combination of milrinone and epinephrine drips post-operatively works well. Pain control and, later, effective diuresis are also important. Cerebral congestion from the new passive circulation to the pulmonary arteries can be a source of significant patient discomfort. Simple maneuvers such as elevating the head of the bed can contribute to great patient comfort by using gravity to promote anterograde blood flow from the cerebral to the pulmonary circulation.

Monitoring these patients for desaturation relative to their physiology is also important; and assessing for the common causes of a desaturated Glenn patient is crucial. The desaturated Glenn patient may pose a serious dilemma for the ICU team. The use of 100% FiO2 and inhaled nitric oxide can be employed. Ultimately, the patient may need to be intubated. In such instances, cardiac catheterization procedure should be pursued to investigate the possible causes. Ensuring adequate hemoglobin levels for Glenn's physiology is important. If the patient requires additional pulmonary blood flow, then an aortopulmonary shunt may be added to the system [34].

These patients require monitoring for high chest tube output and pleural effusions/chylothorax.

### **4.9 Third stage**

The third stage of palliation is called the Fontan procedure or total cavo-pulmonary anastomosis. Similar to the Glenn procedure, acute post-operative management includes avoidance of high PEEP, and high PVR triggers. The majority of Fontan patients will return from the operating room extubated. Typically, the saturations in a patient post Fontan procedure will be around 92–95%—barring the presence of collaterals or pulmonary vein desaturations. They are preload dependent—at some institutions, the initial post-operative fluid management involves giving patient one and half times maintenance fluid volume. After the first 24–36 h, effective diuresis is then initiated.

Inotropic support may involve the use of epinephrine, milrinone, and/or dopamine. Most recently, the potential beneficial use of vasopressin post-operatively has been explored [35].

Arrhythmias are not infrequent. Postoperatively Fontan patients should be observed for supraventricular tachyarrhythmias of all forms (atrial tachyarrhythmias, re-entry tachyarrhythmias, and junctional arrhythmias).

Like in the Glenn patients, the post-operative Fontan patients require monitoring for high chest tube output and pleural effusions/chylothorax.

Any evidence of an acutely failing Fontan physiology [36, 37] should be anticipated and acted upon expeditiously. If there is evidence of an acutely failed Fontan physiology—serious consideration should be given to taking down the Fontan circuit [38].
