CH 3 Pathophysiology of pediatric cardiac disease relevant to ECMO

Question 1

A single ventricle patient with obstructed systemic flow will usually have what ?

Answer 1

Unobstructed pulmonary blood flow

Question 2

Systemic blood flow in a single ventricle patient is largely dependent on what ?

Answer 2

• R > L shunt across the PDA

- Amount of systemic outflow obstruction

Question 3

Single ventricle’s degree of R > L shunting through the PDA is determined by what?

Answer 3

Relative resistances of the systemic and pulmonary vascular beds

Question 4

Where does mixing of the systemic and pulmonary venous return occur ?

Answer 4

Atrial level

Question 5

What patients would have “Ductal Dependent” systemic blood flow?

Answer 5

Single ventricle pt with severe systemic outflow obstruction

Question 6

Single ventricle patient with obstruction of pulmonary blood flow will most likely have what?

Answer 6

Unobstructed Systemic blood flow

Question 7

If pulmonary blood flow is only minimally obstructed, the child may have what ?

Answer 7

Overcirculation of the pulmonary vascular bed at the expense of systemic perfusion

Question 8

Why would a pulmonary atresia patient only have mixing at the atrial level?

Answer 8

Because of the lack of a VSD.

This in turn would create a total obstruction of pulmonary blood flow.

Question 9

If pulmonary blood flow is dependent on L > R shunting across the ductus arteriosus on a single ventricle patient, what needs to be started immediately ?

Answer 9

PGE1 to maintain a PDA.

Question 10

What do all forms of single ventricle CHDs have in common?

Answer 10

Mixing of systemic and pulmonary blood at the atrial level.

Question 11

A new born patient presenting with the folowing would be suggestive of what?
What is the next course of action?

• Severe elevations in pulmonary venous pressures,
• Pulmonary Hypertension
• Hypoxemic
• Cyanotic

Answer 11

Possible single ventricle with restrictive ASD

Assess atrial communication immediately

Prepare for emergent balloon atrial septostomy or surgery

Question 12

For a patient with Hypoplastic Left Heart Syndrome, how can we prevent excessive pulmonary flow which would result in pulmonary edema or low systemic perfusion?

Answer 12

Careful attention to ventilation is crucial. Aim for an Arterial SpO2 between 75 - 85%

Question 13

ECMO should be considered in any single ventricle patients with any or all of the following ?

Answer 13

• Refractory Hypotension
• Circulatory Collapse
• Refractory Hypoxemia
• Dysrhythmias
• Inability to wean from CPB

Question 14

What is the percentage of survival to discharge for patients who underwent single ventricle staged palliation who were placed on ECMO ?

Answer 14

48%

Question 15

What was the difference in survival to discharge for patients placed on ECMO for the follwoing:

1. ) Hypoxemia Vs. Hypotension ?
2. ) Arrhythmias prior to ECMO Vs. No Arrhythmias prior to ECMO ?

Answer 15

1. ) 81% Vs 29%

2. ) 0% Vs. 50%

Question 16

Patients with single ventricle parallel circulation that are placed on ECMO usually require what?
Why?

Answer 16

Much higher ECMO flow

To account for run off into the pulmonary circulation

Question 17

Mild TOF is also know as what?

Answer 17

“Pink TET”

Question 18

Under what CHD is systemic arterial saturation dependent on the degree of obstruction to pulmonary blood flow ?

Answer 18

Right Ventricular Outflow Obstruction

Question 19

In patients with a Modified Blalock Taussing Shunt, when should ECMO be considered?

Answer 19

• Early cases of refractory hypotension unresolved with volume and ventilatory manipulations.
• Refractory/progressive cyanosis

Question 20

In patients with a Modified Blalock Taussing Shunt, where should cannulation for ECMO be considered?

Answer 20

Through chest is sternotomy was performed.
Through the neck is thoracotomy was performed.
- Venous cannulation - Internal Jugular
- Arterial cannulation - Carotid Artery

Question 21

In patients with a Modified Blalock Taussing Shunt, on ECMOoften have paradoxical overcirculation of the pulmonary vascular bed.

How would this patient present?
What can our team do to treat this?

Answer 21

• Chest X-Ray would show diffuse opacification.
• Often with metabolic acidosis.
• The surgeon can clip the shunt to limit pulmonary
  overcirculation.
• Maintain saturations in the 70s.
• PaO2 from 40-50

Question 22

In the post-operative periods for neonates with a severely pressure-loaded LV are at high risk for arrhythmias, ventricular dysfunction, and coronary ischemia. If low cardiac output is evident, ECMO should be considered early.
Describe the cannulation techniques for this patient?

Answer 22

Arterial cannulation: Proximal to the takeoff of the innominate artery and should NOT be angled directly at the aortic valve as this can cause AI & Increase LV afterload to an already compromised LV.

Venous cannulation: RA above the tricuspid valve annulus

Question 23

Name 3 L > R shunts which place the LV under volume loaded conditions ?

Answer 23

VSD
Large PDA
AP window

Question 24

Long standing large L > R shunts can lead to what ?

Answer 24

Significant LV dilation
LA hypertension
PA Hypertension

Question 25

Once PVR drops after birth, an AP window exposes the pulmonary vascular bed to high systemic pressures with high flow. Left untreated, these patients are at risk for what?

Answer 25

Irreversible fixed pulmonary hypertension

Question 26

Cardiac Output on all patients with TAPVR depends on what ?

Answer 26

Atrial R > L shunt

Question 27

What dictates the urgency with which TAPVR repair is undertaken ?

Answer 27

Degree of pulmonary venous obstruction

Question 28

When should a neonate with TAPVR be considered for preoperative or postoperative ECMO ?

Answer 28

Presence of refractory hypoxemia

Question 29

A post operative patient with pulmonary hypertension could benefit from what type of treatment ?

Answer 29

Inhaled Nitric Oxide

Stimulates the vascular smooth muscle cells which results in reduction of smooth muscle tone (vasodilation) and therefore reduces pulmonary artery pressure.

Question 30

In a preoperative patient with severe PVO, what will happen if we give them Nitric Oxide for inhalation ?

Answer 30

Worsen an already challenging situation

Question 31

Will a patient with PA pressures that are persistently 3/4 systemic without hemodynamic effects require ECMO?

Answer 31

No

Question 32

In myocarditis, arrhythmias are due to what?

Answer 32

Diffuse myocardial inflammation and infiltrative processes

Question 33

A patient presenting with a short viral prodrome, cardiogenic shock, ventricular arrhythmias, and heart block would be suggestive of what pathological disease?

Answer 33

Severe myocarditis

Question 34

Treatment for myocarditis should be aggressive and is largely supportive. What are the goals, and how will we achieve those goals?

Answer 34

Goal: Reduce myocardial oxygen demand and maintain end-organ perfusion. (rest & recovery)

Through the use of the following:
Anti-arrhythmics
mechanical ventilation
inotropic support