Hypoplastic Left Heart syndrome

Question 1

Hypoplastic left heart syndrome is a term used to describe a spectrum of defects with the common denominator being

Answer 1

under development of the heart’s left side

-aorta, aortic valve, LV, and MV

Question 2

Hypoplastic left heart syndrome results in

Answer 2

single ventricle physiology & complete mixing of systemic and pulmonary circulation

Question 3

The expected oxygen saturation for a patient with HLHS is

Answer 3

75-80%

Question 4

Describe surgical palliation for HLHS.

Answer 4

• this defect is not correctable and definitive treatment is a heart transplant

Question 5

The three palliative operations for HLHS include:

Answer 5

Stage 1: Norwood- soon after birth
Stage 2: Bidirectional Glenn at 4-12 months old
Stage 3: Fontan at 1.5-3 years old

Question 6

With HLHS, the entire left side from the

Answer 6

mitral valve to the aortic arch is hypoplastic

Question 7

The single ventricle ejects

Answer 7

mixed blood into the pulmonary artery

Question 8

At birth with HLHS, the RV provides

Answer 8

pulmonary blood flow
systemic blood flow is from the PA via the PDA–> ductal dependent*****
If the PDA closes, the neonate will present in shock due to severely reduced systemic perfusion
- most are diagnosed in utero and PGE1 is started to maintain ductal patency

Question 9

With the Stage 1: Norwood with shunt, the connection nbetween

Answer 9

systemic to pulmonary circulation is created

1) atrial septectomy and creation of a common atrium
2) reconstruction of PA to aortic arch
3) ligation of the PDA
4) establish pathway for blood flow to lungs with a BTS/MBTS (right subclavian or synthetic graft to right PA)

Question 10

With the Stage 1: Norwood, the anticipated arterial oxygen saturation is

Answer 10

75-80%**

• if SpO2 is >85% there is excessive pulmonary blood flow
• if SpO2 is <70% there is inadequate pulmonary blood flow (i.e. problems with BTT shunt or lung disease)

Question 11

The Stage II: Bidirectional Glenn requires low

Answer 11

PVR and blood flow is passive***

• maintain adequate volume and low PVR
• expected arterial oxygen saturation is 75-85%
• IVC venous blood continues to flow into the heart and therefore systemic circulation

Question 12

The stage II: bidirectional Glenn is a direct anastomosis between the

Answer 12

SVC and a pulmonary artery branch

“Bidirectional” indicates blood flow to both the right and left pulmonary arteries

Question 13

In the Stage III: Fontan Procedure, the inferior vena cava is

Answer 13

connected to the pulmonary vasculature

-allows for passive blood flow from the IVC to lungs while bypassing the heart

Question 14

The stage III procedure completes the

Answer 14

separation of the pulmonary and systemic circulations

Question 15

The expected arterial oxygenation saturation of the Fontan procedure is

Answer 15

88-93%

Question 16

Prior to stage 1, the PDA must be kept patent with

Answer 16

PGE1 to allow systemic perfusion

Question 17

It is important to restrict excessive_____ in patients with HLHS.

Answer 17

pulmonary blood flow

Question 18

Excessive pulmonary blood flow can be restricted via:

Answer 18

allowing mild hypercarbia (PCO2 45-55 mmHg)
allowing low oxygen concentrations
use of PEEP

Question 19

Higher than expected oxygen saturations may imply

Answer 19

inadequate systemic perfusion and pulmonary overload (consider cerebral oximetry monitoring)

Question 20

Additional considerations for patients with HLHS include:

Answer 20

patients may require inotropic support (i.e. dopamine, milrinone or epinephrine)
minimize myocardial depression
prevention and treatment of pulmonary hypertensive crisis

Question 21

Chronic Fontan complications include:

Answer 21

dysrhythmias
protein losing enteropathy
thrombosis

Question 22

Thrombosis may occur due to

Answer 22

dysrhythmias that cause venous stasis or sluggish flow

Question 23

Protein losing enteropathy is

Answer 23

poorly understood development of hypoalbuminemia despite normal renal and hepatic function

Question 24

Dysrhythmias may occur due to

Answer 24

elevated atrial pressures and atrial suture lines

Question 25

Pulmonary hypertension is the result of

Answer 25

high blood flow and increased pressure in the pulmonary vasculature

Question 26

Pulmonary hypertension is common in

Answer 26

unoperated CHD

Question 27

A child with acute increases in pulmonary artery pressure and intracardiac communication that allows for shunting may result in:

Answer 27

desaturation
bradycardia
systemic hypotension

Question 28

Known factors to increase pulmonary vascular tone**

Answer 28

hypoxemia & use of <30% FiO2
hypercarbia/acidosis
hypothermia
atelectasis
transmitted positive pressure & PEEP
Stress response/stimulation/light anesthesia

Question 29

Known factors that decrease pulmonary vascular resistance****

Answer 29

increasing inspired oxygen to 100%
hyperventilation
potent inhalation agents reduce SVR more than PVR
nitric oxide

Question 30

Vasoconstrictors such as phenylephrine increase _____ more than _____ and are acutely effective in reducing ________ shunting and increasing _____ shunting in the OR.

Answer 30

SVR more than PVR

right to left shunting & increasing left to right shunting

Question 31

Nitric oxide is a powerful

Answer 31

smooth muscle vasodilator with a short half-life

-acts to decrease Calcium levels

Question 32

Nitric oxide is currently used in neonates to promote

Answer 32

capillary and pulmonary dilation to treat pulmonary HTN

Question 33

Overdose of nitric oxide results in

Answer 33

methemoglobin & pulmonary toxicity

Question 34

The nitric oxide should be placed on the

Answer 34

inspiratory limb of the AGM