HLHS and SV

7/30/2019 HLHS and SV

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Hypoplastic Left HeartSyndrome (and stuff regarding

single ventricle physiology)

Enrique Oliver Aregullin Eligio, MD

Miami Childrens Hospital

February 2013


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GOALS

Appreciation of history of Hypoplastic Left HeartSyndrome.

Basic anatomy & physiology.

Understand the LOGIC behind the management ofHLHS (& single ventricle lesions in general).


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Hypoplastic Left Heart Syndrome

Spectrum of underdevelopment of the left ventricularcavity.

Have underdeveloped aortic & mitral valves (stenosis or

atresia). Left ventricle is unable to support systemic circulation

(and, therefore, right ventricle is used as the singleventricle).


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History of HLHS

First described by Maurice Lev in 1952.

Term used by Noonan & Nadas in 1958.

Options offered:

Comfort care

Staged palliative repair, i.e. Norwood procedure

First successful 3-stage completion in 1983 (after multiplesurgeries from 1979).

Cardiac transplant

First successful cardiac transplant: Bailey, Nov. 1985


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Xenotransplantation, Baby Fae

Dr. Leonard Bailey, Loma Linda University MedicalCenter, November 1984.

http://www.babyfae.com


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Anatomy


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HLHS Epidemiology

Low incidence of 1.6 to 3.6 per 10,000 live births, BUT causes23% or cardiac deaths during 1st week of life and 15% duringthe 1st month of life.

Makes up about 2-4% of congenital heart disease.

More commonly males (55% to 67%). With ONE affected child, recurrence risk is about 0.5% to 2%.

12% prevalence of left-sided obstructive lesions in 1st degreerelatives.

15-30% incidence of genetic syndromes and extracardiac

anomalies in patients w/HLHS. Genetic markers: dHAND, HRT1, HRT2, NOTCH.

Moss & Adams, 2008.


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PATHOPHYSIOLOGY

Cardiac development: Flow begets growth.

Altered flow through the left side of the heart:

Reduced/altered flow across the foramen ovale.

Aortic or mitral obstruction.


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Typical Clinical Presentation

Known Congenital Heart Defect

Prenatal Diagnosis

Unknown Congenital Heart Defect Normal pregnancy, labor and delivery

Clinically doing okay until the PDA closes **

Cyanosis that does not improve withoxygen

Many have no other obvious anomalies


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DUCTAL-DEPENDENT LESION

PDA needed to:

Provide systemic perfusion

HLHS **

Critical aortic stenosis

Provide pulmonary blood flow

Tricuspid atresia

Pulmonary atresia

Provide mixing of oxygenated & deoxygenated blood

Transposition of the Great Vessels


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Hyperoxitest

ABG is measured on room air.

Patient is placed on 100% oxygen (intubated) for 10-15minutes, then ABG is repeated.

If problem is respiratory (i.e. hypoventilation), thenPaO2 improves (usually above 200mmHg).

If problem is cardiac (i.e. right-to-left intracardiacshunt), there is little improvement of PaO2.

Primary pulmonary hypertension may also result inlittle improvement of PaO2.

(Oxygen may hasten closure of PDA!)


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Positive Hyperoxitest

Seriously consider initiation of prostaglandin (PGE) ata low dose (0.03 mcg/kg/min) until diagnosis isconfirmed.


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Initial Assessment

ALWAYS

A - Airway B - breathing

C circulation

CXR and ECG usually not very helpful in Dx.


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Physical Findings

Comfortable or in distress?

Cyanosis w/out respiratory distress is cardiac untilproven otherwise

Active or lethargic? Cyanosis?

Degree - saturation usually


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Respiratory Status

Tachypnea but with minimal distresscardiacuntil proven otherwise.


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Respiratory Status

Respiratory distress

Inability of the respiratory system tocompensate for the metabolic acidosis

Concurrent respiratory disease

Unrelenting metabolic acidosis - decreasedcardiac function

Exhaustion


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AssistedVentilation

Intubate if:

Impending respiratory failure

Potentially not necessary to intubate just forPGE therapy if ground transport

Intubate for air transport in PGE dependentbabies


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Assisted Ventilation

Ventilation strategy

Volume ventilation if possible to maintainconsistent minute ventilation in the face of

changing lung compliance

Bigger tidal volumes compared to prematurenewborns (10 cc/kg); lower rates

No need to over-ventilate

40/40/40 club


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Arterial Blood Gases

In congenital heart disease typically:

Compensated or partially compensatedmetabolic acidosis

Arterial PO2 usually low


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Blood Gases

PH accurate accurate lower

PO2 accurate invariable lower

PCO2 accurate accurate higherHCO3(calculated) accurate accurate accurate

Arterial Capillary Venous


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Oxygen

Oxygen is a drug - use it with respect

Oxygen is a pulmonary vasodilator

May worsen pulmonary congestion

Oxygen is a stimulus for the PDA to close

May worsen ductal dependent lesions byspeeding up closure of the PDA

Oxygen is not bad


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Saturation Monitoring

Oxygen saturation reflects tissueoxygenation and usually does not correlatewith PO2.

With pulmonary hypertension will seedifferential cyanosis - shunts right to leftacross the PDA.

The number is not as important as thepatient.


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Prostaglandin Infusion

Purpose is to open the PDA if a ductaldependent lesion is suspected

Can be initiated before a definitive diagnosis

is established

Need a secure IV (PIV, PIC, or UVC-central orin the liver)

Start at low dose 0.03 mcg/kg/min


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Prostaglandins continued

Side effects -

Apnea - be prepared to intubate

Fever

Hypotension - have volume and inotropesavailable

Flushing


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Access

Umbilical is preferred in a newborn

UVC even if in suboptimal position

UAC PIC line

PIV

AVOID groin line if possible


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Fluid Resuscitation

Needed if poorly perfused

5% albumin bolus (5-10 cc/kg)

Watch for and treat hypoglycemia - stresscauses epinephrine release whichincreases utilization of glucose.

PRBC to treat anemia - optimize oxygencarrying capacity.


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Hypotension

Check ionized calcium

Treat with 50-100mg/kg calcium gluconate or10 mg/kg calcium chloride via central access

Dopamine

Epinephrine


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Metabolic Acidosis

Treat metabolic acidosis aggressively(base deficit < -3)

1 meq/kg Na bicarbonate

Repeat blood gas


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Other Systems

Renal function

Urine output

BUN/Cr

Renal ultrasound

Head ultrasound

Liver function tests

Coagulopathy

Thrombocytopenia

R/O sepsis

Genetics


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Fetal Diagnosis


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Fetal Studies

Hornberger, 1995: 21 fetuses with prenatal echos thatshow left-sided obstruction (small mitral valve &ascending aorta) developed HLHS.

Critical aortic stenosis

decreased blood flowthrough left heart LV dilation & dysfunctionendocardial fibroelastosis (EFE) backwards flowacross PFO LV stops growing & eventually shrinks


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HLHS


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NORMAL FETAL 4-CHAMBER


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Case Presentation

Term infant born via SVD

Uncomplicated labor and delivery

APGARs of 8 at 1min., 9 at 5min. Tachypnea noted at 12hrs of life.


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Case Presentation

Airway-Breathing-Circulation

Respiratory rate (60-90 bpm)

Work of breathing (no retractions)

Saturations (80%)

Warm extremities; good cap refill


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Case Presentation

No obvious dysmorphic features.

More Cardiac Exam Findings: No murmur.

Single second heart sound (S2).

Hyperdynamic precordium.


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Case Presentation

Urgent Cardiology Consult

Cardiac History & Physical

Echocardiogram


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Echocardiogram HLHS


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echo


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Case Presentation

BUT:

No beds available immediately

Need to manage infant for 24 hoursbefore transport

NOW what do we do?


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Case Presentation

Intravenous access

UVC (double lumen)

UAC

PIV

PIC

Remember: AVOID groin lines


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Case Presentation

Prostaglandins

0.03 mcg/kg/min

Side effectsApnea

Options ?

Intubate vs nasal cannula air


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Case Presentation

Labs

Arterial (or venous) blood gas

Electrolytes (normalize)

CBC

LFT

Genetics

Lactic acid

Head and Renal ultrasound

ECHO/EKG


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Case Presentation

R/O Sepsis

If no clinical suspicion or maternalindicators no need to start antibiotics

Follow ABG frequently (Q 4 hrs)

Monitor urine output

Monitor for acidosis Watch for hypotension


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Blood Pressure

Blood pressure - systolic and diastolicblood pressures are equally importantnotjust mean!!

Coronary flow to heart dependant ondiastolic BP


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Case Presentation

Saturations 95%

pO2 50

Decreased urine output

Metabolic acidosis

Rising lactic acid

Whats going on?!?


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Chest X-Ray


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Case Presentation

Pulmonary Over Circulation with systemiccompromise

Intubate/hypoventilate

CO2


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Case Presentation

Y- tube Physiology:

Pulmonary Resistance

Lowered by:

- Oxygen

- Prostaglandin

- Resp alkalosis

Raised by:

- PPV

- Hypoxia

- Resp acidosis

Systemic Resistance

Raised by:

- Dopamine

- Epinephrine

To BodyTo Lungs


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Monitoring Innovations

Lactic Acid

Mixed venous oxygen saturation Near infrared spectroscopy


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Pulmonary Atresia


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Hypoplastic RIGHT Heart

Flow begets

growth


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Same Y-tube Physiology

To BodyTo Lungs

But now not

enough blood flow

to lungs


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Ideal Saturation for PDA-dependant

For balanced amount of blood flow to both thelungs and the body in a single ventricle (i.e. Y-tube physiology infant) is:

75% to 85% oxygen saturation

(in upper extremity)


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Options for HLHS in 2013

Comfort Care

Transplant

3-Stage Palliative Repair

Fetal Intervention


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Cardiac Transplant

Fairly good quality of life as transplant recipient(have structurally normal heart).

Obstacles:

Availability of donor heart (approximately 25-30% dieawaiting transplant).

Life-long immunosuppression & risk of infection/CA.

Usual cause of death/organ death: coronary

vasculopathy. Survival: 84% at 1 yr, 76% at 5 yrs., 70% at 7 yrs.

Organ survival MUCH reduced w/subsequenttransplants.


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HLHS Palliative Repair

A. HLHS (sats 80s)B. Norwood repair in 2wks

- Provide systemic BF

- Balance pulmonary BF

C. Glenn repair (SVC to PA)- More pulmonary BF

D. Fontan repair (IVC to PA)

- Relieve volume load to RV- Venous blood totally

bypasses heart (sats

100%)


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Norwood (Stage I)


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HLHS Survival

Standard Risk (i.e. no genetic or extracardiac issues)

1 month85%

1 year80%

5 year73%

Higher Risk

1 month61%

1 year20%


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Fetal Intervention

VERY small balloon catheter is inserted via mothersabdomen, across uterus, through fetal heart acrossaortic valve. Fetal aortic valvuloplasty is performed.

Marginal success with select patients

Must have diagnosis in early 2nd trimester

Absence of genetic or extracardiac anomalies

Early stage of critical aortic stenosis (LV is dilated with

some preserved function, but not yet involuted) Favorable maternal habitus


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Why Fontans Fail

As we age, the ventricular EDP rises.

In Fontan patients, the CVP must

exceed the EDP. Eventually, the EDP

will rise to an intolerable level.

C f C /


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Comfort Care/Hospice

Why is it a viable option in 2010?

The Fontan is doomed to fail. Dr. Reddington, ACC2003

Fontan patients will develop protein-losing enteropathy,ventricular dysfunction, hypoxemia, thromboembolism,arrhythmias and liver failure.

S


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Summary

HLHS is universally lethal w/out treatment.

A patent foramen ovale & ductus arteriosus are necessary forsurvival.

Echocardiogram is modality of choice for diagnosis.

Management of the neonate w/HLHS is complicated: PGE isnecessary as well as ventilation/support to permit sats 75% to85% and no acidosis.

Transplant and staged repair are not w/out their complications(survival for both about 70% in 5 yrs).

Comfort care & fetal interventions are options to be considered.

Decision-making is a TEAM effort by pt. family & medical team.

HLHS and SV

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