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CASE PRESENTATIONCASE PRESENTATION

This is a two-day old male infant, born weighting 2730 grams (six pounds, two ounces) after a full-term pregnancy complicated by influenza in the first trimester, was found to be tachypneic on the second day of life. Examination at that time also revealed weak peripheral pulses. He was transferred to the university hospital.

CASE PRESENTATION (cont.)CASE PRESENTATION (cont.)

On admission, physical examination revealed a small tachypneic infant with grayish cyanosis of the lips. The respiratory rate was 89 per minute and the heart rate 170 per minute. The lungs were clear to auscultation. A right ventricular lift was noted at the left sternal border and in the epigastric area. No thrills were present.

CASE PRESENTATION (cont.)CASE PRESENTATION (cont.)

The first heart sound was normal but the second sound was closely split with a loud, snappy pulmonic component. A short, soft ejection systolic murmur was present at the fourth left intercostal space. The peripheral pulses could not be palpated in either the upper or lower extremities. The liver edge was palpable 3-4 cm below the RCM.

QUESTIONSQUESTIONS

1. The differential diagnosis of congestive heart failure in the first few days of life include all the following except:A. TAPVRB. MyocarditisC. Hypoplastic left heart syndromeD. Preductal coarctation of the aortaE. VSD

QUESTIONS (cont.)QUESTIONS (cont.)

2. Anatomical components of the hypoplastic heart syndrome include all the following except:

A. Aortic atresia B. Minute left ventricle C. Mitral atresia, stenosis or hypoplasia D. PDA E. Pulmonary atresia

QUESTIONS (cont.)QUESTIONS (cont.)

3. Which of the following findings is not a typical one in patients with HLHS?A. Fairly sudden onset of tachypnea and dyspnea during the first week of life.B. Loud aortic component of the S2.C. Loud pulmonary component of the S2.D. Weak peripheral pulses.E. Cyanosis

HYPOPLASTIC LEFT HYPOPLASTIC LEFT HEART SYNDROMEHEART SYNDROME

Gerardo Gonzalez, MD

HLHS - HistoryHLHS - History

First described in 1952 by Lev as the pathologic complex “hypoplasia of the aortic tract”, including cases of:– isolated hypoplasia of the aorta– hypoplasia of the aorta and VSD– hypoplasia of the aorta with aortic stenosis or atresia,

with or without mitral stenosis or atresia

In 1958, Noonan and Nadas termed these lesions as “hypoplastic left heart syndrome”.

HLHS - EmbryologyHLHS - Embryology

The embryologic cause is not fully understood.

It probably results from a limitation of either LV inflow or outflow, such as the development of severe AS early.

HLHS - GeneticsHLHS - Genetics

Familial inheritance:– Autosomal recessive and multifactorial inheritance have

both been postulated.– Sibling recurrence risk: 0.5%– Sibling recurrence for all other cardiac malformations:

2.2%

Definable genetic disorder (28%):– Turner Syndrome – Noonan Syndrome– Trisomy 13, 18, 21, or other microdeletion syndromes

HLHS - EpidemiologyHLHS - Epidemiology

Each year, approximately 1000 infants with HLHS are born in the US.

Prevalence: 0.016-0.27 per 1000 live births.In pathologic series, it accounts for 1.4-3.8

of congenital heart disease.Third cause of critical CHD in the newborn.Male predominance: 57-70%.23% of all neonatal mortality from CHD.

HLHS – Epidemiology (cont.)HLHS – Epidemiology (cont.)

Infants with HLHS are usually full term; they have a normal birth weight and few significant extracardiac malformations.

Prematurity and SGA at birth are observed in 5.5%.

Noncardiac malformations are uncommon (12%).

Serious or major malformations are rare (2.3%)

Anatomy

HLHS - PathophysiologyHLHS - Pathophysiology

The term HLHS is used to describe a related group of anomalies that include underdevelopment of the left side of the heart (e.g. atresia of the aortic or mitral orifice) and hypoplasia of the ascending aorta.

The left ventricle may be small and nonfunctional or totally atretic.

HLHS - PathophysiologyHLHS - Pathophysiology

The right ventricle maintains both pulmonary and systemic circulations.

Pulmonary venous blood passed through an atrial defect or dilated foramen ovale from the left to the right side of the heart, where it mixes with systemic venous blood (TOTAL MIXING LESION).

The ventricular septum is usually intact.

HLHS - PathophysiologyHLHS - Pathophysiology

The major hemodynamic abnormalities are:– Inadequate maintenance of the systemic

circulation.– Pulmonary venous hypertension (if

restrictive foramen ovale).– Pulmonary overcirculation (if moderate

or large ASD).

Anatomy

HLHS – Clinical manifestationsHLHS – Clinical manifestations

Most infants are diagnosed in the first few hours or days of life.

A grayish blue color of the skin is soon apparent (denoting a mix of cyanosis and hypoperfusion).

If the PDA partially closes, signs of systemic hyporperfusion and shock predominate.

HLHS – Clinical manifestationsHLHS – Clinical manifestations

Signs of HF usually appear within the first few days or weeks of life (dyspnea, hepatomegaly, low cardiac output).

Peripheral pulses may be weak or absent.Cardiac enlargement is usual, with a right

ventricular parasternal lift.A nondescript systolic murmur is usually

present.

HLHS – Clinical manifestationsHLHS – Clinical manifestations

Extracardiac anomalies (particularly of the kidney and CNS, but also diaphragmatic hernia, omphalocele and hypospadia) may be present.

HLHS – Diagnostic toolsHLHS – Diagnostic tools

CXR:– Heart variable in size (1st day of life). – Cardiomegaly develops rapidly, associated with

increased pulmonary vascularity.

Chest X-ray of a two-day- old boy with HLHS

HLHS – Diagnostic toolsHLHS – Diagnostic tools

Electrocardiogram:– Initially, may show only the normal right

ventricular predominance.– Later, P waves become prominent and right

ventricular hypertrophy is usual.

ECG

ECG

HLHS – Diagnostic toolsHLHS – Diagnostic tools

Echocardiogram:– Is diagnostic.– There is absence or hypoplasia of the mitral

valve and aortic root, a variable small left atrium and left ventricle, and a large right atrium and right ventricle.

– The size of the atrial communication can be assessed directly and by pulsed and color flow Doppler studies.

HLHS – Diagnostic toolsHLHS – Diagnostic tools

Echocardiogram (cont.):– Suprasternal notch views identify the small

ascending aorta and transverse aortic arch (may also demonstrate a discrete CoAo).

– Doppler demonstrates the absence of anterograde flow in the ascending aorta and retrograde flow via the ductus arteriosum.

RA

RV

LA

LA

NORMAL 4-CHAMBER VIEW

LV

4-CHAMBER VIEW - HLHS

4-CHAMBER VIEW – AORTIC ATRESIA WITH MITRAL ATRESIA

NORMAL SHORT-AXIS VIEW

AO

RV

PARA

LA

SHORT-AXIS VIEW - HLHS

LA

LV AO

RV

NORMAL LONG-AXIS VIEW

LONG-AXIS VIEW - HLHS

HLHS – Diagnostic toolsHLHS – Diagnostic tools

Cardiac Catheterization and Angiography:– These are no longer routinely necessary for the

diagnosis of HLHS.– In patient with severe restriction at the

interatrial level, a ballon septostomy would be indicated if the patient is not a candidate for surgical palliation at that time.

HLHS - TreatmentHLHS - Treatment

There is variable success in the surgical therapy of HLHS.

Management options include:– Norwood procedure– Heart transplantation– Supportive expectant care

HLHS - TreatmentHLHS - Treatment

Norwood procedure: Preoperative management

– correction of acidosis and hypoglycemia– maintenance of the patency of the PDA (with PGE1) to

support systemic blood flow– prevention of hypothermia– 21% FiO2, with addition of 2% to 4% CO2 (PCO2

aimed at 50, pH 7.30)– Selective use of small amount of inotropic agents

(sepsis or RV failure)

BEFORE NORWOOD PROCEDURE

HLHS - TreatmentHLHS - Treatment

Norwood Procedure: First Stage– Atrial septectomy.– Transection and ligation of the main pulmonary

artery.– Connection of the proximal pulmonary artery to

the transversely opened hypoplastic aortic arch (“neoaorta”). The coarcted segment of the aorta is repaired.

HLHS - TreatmentHLHS - Treatment

Norwood Procedure: First Stage (cont.)– Modified Blalock-Taussig shunt.

– 90% early survival (if in a timely fashion at selected institutions).

Norwood:Stage I

AFTER NORWOODSTAGE I

HLHS - TreatmentHLHS - Treatment

Norwood Procedure: Second Stage– All prior shunts are removed.– Glenn anastomosis (bidireccional

cavopulmonary procedure): the superior vena cava is connected to the pulmonary arteries.

– 5% mortality.– Usually performed around 6 months of age.

AFTERNORWOODSTAGE II

HLHS - TreatmentHLHS - Treatment

Norwood procedure: Third Stage – Modified Fontan Procedure (cavopulmonary

isolation): the inferior vena cava is connected to the pulmonary arteries, via either an intra-atrial of external baffle.

– 10-12% mortality.– Usually performed around the age of 2 years.

After Stage III of Norwood Procedure

HLHS - TreatmentHLHS - Treatment

After the third stage, all systemic venous return enters the pulmonary circulation directly.

Pulmonary venous flow enters the left atrium and is directed across the atrial septum to the tricuspid valve, and subsequently to the right (now the systemic) ventricle.

HLHS - TreatmentHLHS - Treatment

Blood leaves the right ventricle via the neoaorta, which supplies the systemic circulation.

Coronary blood flow is provided by the old aortic root, now attached to the neoaorta.

HLHS - TreatmentHLHS - Treatment

Cardiac Transplantation:– It is an alternative, either

In the immediate neonatal period (obviating stage I of the Norwood procedure)

After a successful stage I Norwood procedure

– Patients have the chronic risk of an organ rejection and lifelong immunosuppressive therapy.

HLHS – TreatmentHLHS – Treatment

Five year survival:– 70% for staged palliation (Norwood

procedure).– 75% for transplantation.

HLHS - TreatmentHLHS - Treatment

Supportive expectant care (“do nothing”)

– Especially true when multiple noncardiac congenital anomalies exist or when serious multiorgan system damage is present.

HLHS – Pitfalls for the HLHS – Pitfalls for the NurseryNursery

Avoid using oxygen despite low pulse oximetry saturation.

Increasing FiO2 will lower pulmonary vascular resistance and increase blood flow to the lungs, which are already “overcirculated”, thereby worsening systemic perfusion.

HLHS – Pitfalls for the HLHS – Pitfalls for the NurseryNursery

Avoid overventilating the infant.Carbon dioxide is a pulmonary vasoconstrictor and may improve systemic perfusion and cardiac output. Try to maintain normal or mildly elevated PaCO2 levels.

HLHS - SummaryHLHS - SummaryIt is a collective term describing a group of

cardiac malformations that share various degrees of hypoplasia of the structures of the left side of the heart.

Over 95% of patients with HLHS will die if left untreated during the first month of life.

Echocardiogram is the diagnostic procedure. Surgical intervention has become a medical

standard.