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A Broken Heart: Hypoplastic Left Heart Syndrome Part 3

Third Stage Repair and Heart Transplant

Suzan Miller-Hoover DNP, RN, CCNS, CCRN-K

Hypoplastic Left Heart Syndrome

The child with HLHS is now ready for the final palliation surgery, the Norwood stage III or Fontan. While this surgery is considered the final surgery; heart transplantation may be the final stage if the three Norwood procedures fail.

Controversy still prevails as to when to complete the Fontan. In an effort to minimize end organ exposure to hypoperfusion, many institutions are completing the Fontan at 2 to 3 years of age. Other organizations delay the Fontan completion until it is physiologically indicated, the child experiences increased cyanosis with activity, or at 3 to 5 years of age. The literature suggests that early Fontan completion may result in a higher risk for prolonged recovery and Fontan failure (Feinstein, Benson, Dubin, Cohen, Maxey,... & Martin, 2012; Department of Surgery at the University of California San Francisco, 2016).

The success of the Fontan depends on the condition of the right atria, right ventricle, and tricuspid valve. Because the right ventricle was never meant to perform as the systemic pump there is an increased risk for right-sided heart failure over time.

Completion of the Fontan separates the systemic and pulmonary circulation. The pulmonary circulation will passively flow from the inferior and superior vena cava to the lungs returning oxygenated blood to the right ventricle via the conduit connecting right and left atria. The blood in the right ventricle is then pumped to the systemic circulation via the connection between the pulmonary artery and aorta.

Many of the infants with HLHS will survive all three surgeries, with the expectation of 95% short-term survival, 77% to 95% survival at five years of age, 72% to 91% at 10 years of age, and 87% survival rate at 20 years of age (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco, 2016).

Postoperative care includes persistent pleural effusion treatment and afterload reduction. Patients may experience normal preload and right ventricular contractility postoperatively; however, there may be increased afterload. Reducing both pulmonary vascular resistance and systemic vascular resistance may improve cardiac performance and clinical outcomes. Due to the lack of studies regarding the efficacy of afterload reducers in HLHS patients; use of these drugs should be on a case to case basis to ensure that the benefit justifies the use (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco, 2016).

Postoperative HLHS patients may also experience thromboembolic events during the first postoperative year and again 10 years after the surgery was completed. One quarter of the HLHS patients are at risk for a thromboembolic event due to the passive low-flow in the pulmonary circulation. Because of the significant number of bleeding complications associated with thrombolytic therapy in children, thrombolytic therapy should be reserved for those patients with thrombosis causing clinical issues (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco, 2016).

Life-long follow-up is necessary for the HLHS patient. This follow-up should include but is not limited to yearly cardiology appointments, echocardiography, monitoring of liver function, cardiac MRIs, thrombolytic therapy and monitoring for arrhythmias. Women with Fontan circulation may successfully complete a pregnancy; however, significant complications may occur and may be detrimental to the maternal Fontan circulation (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco, 2016).

Patients with HLHS may require a heart transplant as rescue therapy at any point during their treatment. There is no consensus for optimal timing of heart transplantation. Indications for heart transplant include:
Primary transplant for infants with poor RV function
  •   Norwood stage I palliation patients who are poor candidates for stage II
  •   Norwood stage II palliation patients with poor RV function and tricuspid regurgitation
  •   Norwood stage III palliation patients with ventricular systolic or diastolic dysfunction, protein-losing
       enteropathy, plastic bronchitis, refractory arrhythmias, saturations less than 80% after Fontan and less
       than 70% after Glenn
     (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco,
     2016)

Children listed for transplant have the highest waiting list mortality; approximately 21% of listed Fontan patients died waiting for a heart. Only 76% of patients receiving a heart transplant will survive to one year which is significantly less than the 90% survival rate of other pediatric organ recipients. Medical comorbidities such as renal, pulmonary, hepatic insufficiency, and a panel reactive antibody test greater than 10% which may lead to a higher risk of rejection (Feinstein, Benson, Dubin et al., 2012; Department of Surgery at the University of California San Francisco, 2016).

In summary, improvements in treatment and outcomes in the past three decades support the expectation that 70% of newborns born today with HLHS may reach adulthood. Although current surgical strategies remain palliative and a great deal remains to be understood regarding long-term co-morbidities and quality of life, the work of numerous agencies on congenital heart disease may reveal improvements in HLHS management.



References
Department of Surgery at the University of California San Francisco. (2016). Norwood procedure. Retrieved from: http://pediatricct.surgery.ucsf.edu/conditions--procedures/norwood-procedure.aspx

Feinstein, J., Benson, D., Dubin, A., Cohen, M., Maxey, D….& Martin, G. (2012). JACC White Paper: Hypoplastic left heart syndrome: Current considerations and expectations. Retrieved from: http://www.sciencedirect.com/science/article/pii/S0735109711033420

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