Hypoplastic Left Heart Syndrome - 2 Nursing CEs

Author: Kristi Hudson RN MSN CCRN

Written: December 29, 2006

Course Description

This course is designed to give an overview of the infant with Hypoplastic Left Heart Syndrome (HLHS). Focus will be placed on the pathophysiology, diagnosis as well as medical/surgical treatment options. Nursing assessment and interventions both pre and post op will also be presented. Family education regarding this syndrome will be the final focus of this course.

Course Objectives

Upon completion of this course the student will be able to:

• Describe and define HLHS
• Discuss the pathophysiology associated with HLHS
• Explain how HLHS is diagnosed.
• List possible medical/surgical interventions for HLHS
• State the proper nursing assessment for HLHS
• Discuss nursing interventions for the patient with HLHS
• Describe the necessary patient/family educational components

Define Hypoplastic Left Heart Syndrome (HLHS):

Hypoplastic Left Heart Syndrome (HLHS) is a group of congenital cardiac anomalies that are characterized by marked hypoplasia (incomplete or arrested development of an organ or a part), or absence of the left ventricle with severe hypoplasia of the ascending aorta. HLHS is a rare disorder that begins in utero when there is inadequate growth of the left ventricle and associated structures.

Pathophysiology of HLHS:

Infants with HLHS have a complex cardiovascular physiology. These infants have fully saturated pulmonary venous blood returning to the left atrium (from the lungs) that cannot flow into the left ventricle and to the rest of the body due to atresia, hypoplasia or stenosis of the mitral valve. To compensate for this lack of oxygenated blood flow, blood must cross the atrial septum and mix with desaturated systemic venous blood which is in the right atrium. Mixed venous blood is then sent to the right ventricle which now has the job of moving blood “both” to the lungs as well as the systemic circulation (this is done by moving blood through the Ductus Arteriosus).  The end result is that poorly oxygenated blood is sent through the systemic circulation causing a plethora of system conditions such as poor perfusion, metabolic acidosis and organ failure. Because coronary artery and cerebral perfusion are also dependent on systemic circulation through the Ductus Arteriosus; the infant is at risk for myocardial and/or cerebral ischemia as well.

Diagnosis:

Diagnosis of HLHS can be made by the following:

Chest X-ray – Cardiomegaly and increased veno-vasucular markings are typically present. Marked pulmonary edema maybe noted in infants with obstructed pulmonary venous return (Note: Chest X-ray findings alone are not specific enough to diagnosis HLHS).

Echocardiogram (with Doppler) – This is the test of “choice” for diagnosing HLHS. Two dimensional imaging clearly shows the Hypoplastic left ventricle and ascending aorta. An echocardiogram will also show enlargement of the right atrium, right ventricle, tricuspid valve and the main pulmonary artery. (Note: other structural abnormalities should be ruled out).

Electrocardiogram – This test typically shows sinus tachycardia, right axis deviation, right atrial enlargement and right ventricular hypertrophy.

Pre-Op Nursing Assessment: The role of the nurse in the pre-operative phase is pivotal as slight changes in vital signs, appearance and/or behavior can significantly impact the infants overall medical status. The following are clinical indicators that may be present in infants with HLHS:

Cardiac Assessment/Examination:

• Palpable right ventricular impulse
• Normal first heart sound (S1)
• Loud second heart sound (S2)
• Nonspecific, soft, systolic ejection murmur (at left sternal boarder)
• High pitched holosystolic murmur at lower sternal border
• Diastolic flow rumble over the pericardium

Other Clinical Signs and Symptoms:

• Tachypnea
• Poor feeding
• Respiratory distress
• Cyanosis
• Vascular collapse (often mistaken for sepsis)
• Clinical signs of congestive heart failure
• Decreased peripheral perfusion

Pre-Op Medical Interventions/Treatment:

Caring for infants with HLHS depends on the severity of the condition as well as the family wishes. The following treatment options can be offered:

• Prostaglandin (PGE-1) can be started in a continuous IV drip to assist with keeping the Ductus Arteriosus open (this helps maintain the balance between the pulmonary vascular resistance (PVR) and the systemic vascular resistance (SVR)).
• Prostaglandin is initially started at a rate of 0.05 to 0.1 mcg/kg per minute.
• Additional cardiovascular medication drips are often started to maximize the ability of the heart to move oxygenated blood to the systemic circulation (Dopamine, Dobutamine, Neosynephrine and Milrinone for example).
• Diuretics may be required to assist with decreasing volume load on the right ventricle.
• Mechanical Ventilation will be required (Oxygen saturations of 75% to 85% by pulse oximetry suggest adequate balance between systemic and pulmonary blood flow).

Surgical Intervention:

The Norwood Operation (a multi-staged operation) that requires an open heart approach and cardiopulmonary bypass consists of:

• Part One – provides a shunt (usually a Blalock-Taussig or Sano shunt), enlarges the aorta and provides adequate mixing of atrial blood with an atrial septostomy.
• Part Two – consists of a hemi-fontan operation.
• Part Three – consists of a complete fontan operation.

Note: phase one of the Norwood operation usually occurs within the first several days of life. The second phase of the Norwood operation usually occurs when the infant is 3-6 months old and the final phase usually occurs when the infant is between 18 and 36 months old.

Post- Op Nursing Assessment and Care:

The critical care nurse can most effectively care for the infant by attaining a good intra-operative report from the anesthesiologist. The following information should be attained (after phase one of the Norwood operation):

• Colloid/Crystalloid fluid balance
• Blood products transfused (and availability for the post op course)
• Duration of cardiopulmonary bypass and circulatory arrest
• Size and type of shunt that was placed
• Any other pertinent information

Additional Clinical Assessment (Monitor for signs of the following):

• Monitor for low cardiac output (skin color, heart rate, warm extremities, capillary refill)
• Changes in vital signs
• Urine output (1ml/kg/hr)
• Hypoxemia
• Bleeding
• Infection
• Side effects of medication (actions, potential effects)
• Metabolic acidosis
• Monitor Svo2
• Any appearance or behavioral changes

Post-Op Nursing Interventions:

• Maintenance of intra cardiac catheters (calibration, zeroing, leveling).
• Moment to moment hemodynamic monitoring.
• Calibration of Svo2 monitors.
• Assure absence of air in lines and catheters (infants at greater risk for air emboli).
• Maintenance of all vasoactive and cardiovascular medications.
• Sedation Control (infant may be on Neuromuscular blockade for the first 24 to 48 hours and benzo-diazepines (Lorazepam 0.1 mg/kg every 4 hours) for the first 12 to 24 hours.
• Pain Control (Fentanyl IV infusion of 5 to 10 µg/kg per hour is used for pain control).
• Coordination of care between all healthcare professionals.
• Patient/Family Education (provide frequent and accurate information).

Note: In the post-op stage, the infant is still at risk for insufficient oxygen delivery due to the fact that regardless of the Norwood Operation they still only have one functioning ventricle. Fatal hemodynamic disturbances are still possible (post Norwood Operation still leaves the infant with a 25% mortality rate).

Family Education:

After the phase one portion of the Norwood operation, infants require constant monitoring. Parents are instructed to observe their infants carefully and become accustomed to the infants normal appearance and behavior. Parents need to be instructed to notify the infant’s physician immediately if they note any variation from the norm (make sure parents have all necessary contact numbers prior to discharging the infant). Additional parent education includes:

• Education regarding the medications the infant will need to take (and the importance of not missing doses).
• Stress reduction (recommend support groups).
• Importance of keeping all follow-up appointments.
• Reinforcement that they “are” competent parents.
• Educate parents to normal and disease related infant/child care.
• Infant/Child activity restrictions.
• Future surgeries for the infant
• Promote infant development stimulation

  References

Lange, R., RN, BSN. (2005). Hypoplastic left heart syndrome. Retrieved on December 29, 2006 at:

http://www.childrensheartcenter.com/Video/Renna/NursingIssuesHLHHandouts.pdf

Mayo Clinic. (2006). Treatment options for hypoplastic left heart syndrome. Retrieved on December 30, 2006 at:

http://www.mayoclinic.org/hlhs/treatment.html

Ohye, R., G. M.D. (2006). Hypoplastic left heart syndrome and staged Norwood procedure. Retrieved on December 29, 2006 at:

http://www.emedicine.com/ped/topic2825.htm

Rao, P., S. M.D. (2006). Hypoplastic left heart syndrome. Retrieved on December 29, 2006 at:

http://www.emedicine.com/ped/topic1131.htm

Soetenga, D., RN, MS & Mussato, K., A., RN, BSN. (2004). Management of infants with hypoplastic left heart syndrome. Crit. Care Nurse. 2004; Dec. 24(6): 46-66.