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Pediatrics > Single Ventricle Hypoplastic Left Heart Syndrome Hypoplastic Right Heart Syndrome > Flashcards

Single Ventricle Hypoplastic Left Heart Syndrome Hypoplastic Right Heart Syndrome Flashcards

1
Q

The term single ventricle refers

A

to any congenital cardiac anomaly in which one ventricle is hypoplastic or absent

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2
Q

significant hypoplasia of either ______ necessitates______

A

A-V valve, or apical portion of the LV or RV, necessitates single ventricle physiology.

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3
Q

Single Ventricle Type Defects

A

HypoplasticLeftHeartSyndrome  HypoplasticRightHeartSyndrome  DoubleOutletRightVentricle  DoubleInletleftventricle  Complete AVSD  MitralValveAtresia  TricuspidAtresia  Pulmonary atresia

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4
Q

Single Ventricle Physiology -overview

A

 Single functional pumping chamber  Valves/Outflow tracts may be disrupted  Goal: Must control/balance PA and Aortic flow

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5
Q

HLHS was first successfully treated in the

A

mid- 1980’s by Dr. William Norwood, working out of Philadelphia Children’s Hospital under Dr. Aldo Castaneda.

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6
Q

HLHS fatality before surgery

A

 HLHS had been nearly 100% fatal. Success rates were low, more of the infants were given a second chance at life through palliative surgeries.
 Since these procedures were developed recently, the oldest patients are just reaching adulthood.

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7
Q

Dr. William Norwood reports 1st successful case in

A

1983

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8
Q

HLHS PDA perfuses

A

the coronaries

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9
Q

most prominent case in HLHS

A

Baby Fae, the little girl who received the baboon heart transplant in 1984, is probably the most prominent case of HLHS

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10
Q

Prostaglandins (PGE1) - bought time to improve results

A

1986

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11
Q

HLHS is a severe congenital heart defect in which

A

The left side of the heart does not develop.

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12
Q

HLHS Characteristics

A

 Atretic, hypoplastic aorta and arch
 Large PDA (only blood flow to body)
 Hypoplastic LV
 Small MV and/or AV
 Hopefully, an ASD allowing blood returning from lungs to reach the single ventricle.
(ASD may be restrictive or non-restrictive)

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13
Q

Infants with HLHS who are born with a severely restricted or no inter-atrial communication (a rare occurrence) show

A

profound hypoxemia with increased LA/ PA pressures

pH 7.17 pO2 26 pCO2 58 BE-7.8

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14
Q

In infants with a large, unobstructed ASD, the blood flow

A

from

the LA to the RA increases (L->R).

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15
Q

is is the first attempt to balance the pulmonary and systemic circulations

A

ASD. QP/QS=1

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16
Q

Hypoplastic left heart syndrome (HLHS) is the most common

A

form of congenital heart disease that results in a functional single ventricle

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17
Q

It is estimated that HLHS occurs in

A

0.16 to 0.18 per 1000 live births. Males > Females  No environmental risk factors have been identified

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18
Q

Without surgery, hypoplastic left heart syndrome

A

is uniformly fatal usually within the first 2 weeks of life.

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19
Q

embryological cause

A

The endocardial tube gets pinched shut in a region that becomes the future ventricle, hypoplastic heart syndrome will occur.

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20
Q

If the pinched part of the endocardial tube is the bulbus-cordis region

A

of the developing heart, hypoplastic RIGHT syndrome will occur.

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21
Q

If the pinched part of the endocardial tube is the ventricular region

A

it will be the LEFT side that is hypoplastic

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22
Q

Hypoplastic right heart syndrome (HRHS) refers to____ and causes_____

A

underdevelopment of the right sided structures of the heart.

 These defects cause inadequate blood flow to the lungs and thus, a cyanotic infant.

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23
Q

The major problem with HRHS

A

pulmonary valve atresia

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24
Q

Secondary problems with HRHS include

A

hypoplastic RV  A small TV  A hypoplastic pulmonary artery.

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25
Q

survival rate of hrhs

A

he survival rate is predicted to be 15-30 years post-Fontan
This does NOT mean the child will die at this time. It MEANS that the heart function deteriorated and the child will be listed for transplant.

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26
Q

Other parents feel that ,with advances in medical techonology

A

still needing more work, they prefer to buy time for improvement by choosing the Fontan route.

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27
Q

The goal of surgical reconstruction is to relieve

A

obstruction to systemic flow, un-restrict blood flow from left to right atrium, and create a source of adequate pulmonary blood flow.

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28
Q

The ultimate goal is to create

A

parallel circulations and balance the pulmonary and systemic blood flow (Qp/Qs)

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29
Q

Immediate Palliation for HLHS/HRHS

A

 Balloon Atrial Septostomy (Rashkind Procedure)  Blade Septectomy (Hanlon Procedure) –not used much

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30
Q

The first stage, the Norwood procedure is typically performed

A

within the first week(s) of life.

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31
Q

The second stage, the Bi-directional Glenn or Hemi- Fontan, is typically performed

A

before the infant is 6 months old.

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32
Q

the Completion Fontan operation is completed at

A

18 months to two years old,

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33
Q

DHCA Procedure: on arrest, the surgeon does the following:

A

 Close PDA
 Enlarge aorta (create neo-aorta)
 Add Systemic-PA shunt during warming  Modified B-T (3.5 mm shunt size-average)  Sano (5.0 mm shunt size-average)

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34
Q

The Sano Shunt showed improvement

A

in the survival of newborn babies with HLHS.

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35
Q

The Sano Shunt is constructed from

A

slightly larger Gortex tube graft than that used for the modified BT shunt. Generally a 5 mm tube graft is selected in contrast to the 3.5 mm graft.

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36
Q

Distally, the Sano graft is connected

A

to the main PA between the right and left pulmonary artery takeoffs. The proximal end of the shunt is connected to a limited infundibular incision in the RV.

37
Q

MBTS (Subclavian-PA) charac.

A

 May have preferential right PA flow
 Smaller shunt that may clot post-op
 Rocky course in the OR
 More stable in the PICU post-op

38
Q

Sano (RV-PA)

A

 More centrally located on PA
 Higher pressure shunt  Larger shunt  More stable in the OR
 Rocky course in the PICU

39
Q

Survival rates with Norwood procedure

A

Today, about 90 percent of babies presenting with HLHS can be expected to survive their Norwood operation; truly a success given that 20+ years ago the outlook was hopeless.

40
Q

OK, so now I have new pulmonary (MBTS) and systemic blood flow (Neo- aorta), how can I manage it?

A

By controlling PVR and SVR you can control the preferential flow of blood
Pressure = Flow x Resistance (in case you haven’t seen this before)
 The surgery set the flow parameters (conduit size)  Post-op manipulates the resistance (PVR/SVR)

41
Q

In HLHS, total blood flow coming from the heart can be considered

A

to be a zero sum game.
 Thus, when more blood is directed to one circulation, less is available for the competing circuit.
 Sound a little like left heart bypass?

42
Q

With parallel circulation, pulmonary and systemic blood flow is determined by the

A

ratio of Pulmonary vascular resistance (PVR) to Systemic vascular resistance (SVR).

43
Q

Qp/Qs describes how the cardiac output from

A

the single ventricle is partitioned. If a marked discrepancy occurs in blood flow to the pulmonary and systemic circulations, rapid onset of hemodynamic instability will occur.

44
Q

How do you think the (Qp/Qs) ratio will be altered if I increase the shunt size? Surgical Shunt (BT/Sano)

A

The BT shunt/Sano connecting the systemic circulation to the pulmonary circulation is the single largest component of resistance.

45
Q

Surgical Shunt (BT/Sano) The proper shunt size for each patient is determined

A

initially by the patient’s size and is confirmed by hemodynamic data and oxygen saturations.

46
Q

Surgical Shunt (BT/Sano) The Qp/Qs ratio is calculated after cardiopulmonary

A

bypass is discontinued.

 As in preoperative management, the goal is to achieve aQ p/Qs ratio of 1.0.

47
Q

(Qp/Qs) Post-operative Monitoring

A

Recent articles indicate the usefulness of mixed venous oxygen saturation (SvO2) monitoring to estimate pulmonary-to-systemic blood flow ratio (Qp/Qs) in perioperative management of the Norwood procedure

48
Q

Increased PBF (Decreased PVR)

A

 Although increased pulmonary blood flow results in higher oxygen saturation, systemic blood flow is decreased.
 Perfusion becomes poor, and metabolic acidosis and oliguria may develop.

49
Q

Decreased PBF (Increased PVR)

A

 If PVR is significantly higher than SVR, systemic blood flow is increased at the expense of pulmonary blood flow.
 This may result in profound hypoxemia

50
Q

Pulmonary Vascular Resistance (PVR)

Increase

A

↓ FiO2  ↑ CO2  ↓ pH  PEEP

51
Q

Pulmonary Vascular Resistance (PVR) decrease

A

 ↑ FiO2  ↓ CO2  ↑ pH

 iNO (inhaled nitric oxide)

52
Q

Systemic Vascular Resistance (SVR) increase

A

 ↑ Ph  ↑ FiO2  Vasoconstrictors

53
Q

Systemic Vascular Resistance (SVR) decrease

A

 ↑ CO2*  Vasodilators

54
Q

Qp/Qs increasing PVR

 PVR can also be increased by

A

y maintaining the hematocrit at greater than 40%, a state that optimizes oxygen-carrying capacity and increases the viscosity of the blood increased viscosity
Flow = ΔP x πr4 L x V x 8

55
Q 
Bidirectional Glenn (BDG) and Hemi-Fontan Procedures (HFP) - Stage II
 Preformed at around
A

6 months

56
Q

Cyanosis increasing between stages I and II

A

would shorten the duration of time between surgeries

57
Q

Bidirectional Glenn (BDG) and Hemi-Fontan Procedures (HFP) - Stage II done with DHCA or off CPB

A

 Take down systemic-PA shunt

 Occlude SVC flow  Anastamosis done right PA to the SVC

58
Q

Hemi-Fontan Procedure

(Bi-directional Cavopulmonary Anastomosis) CHARACTERISTICS

A

 Anastamosis PA/Right atrial appendage  SVC is patched

59
Q

Completion Fontan
(Stage III)
 Two choices:

A

 Intracardiac Baffle  Extracardiac Conduit

60
Q

After a Fontan operation, the pressure in the veins will be higher than normal, to

A

overcome this resistance and maintain blood flow. (high CVP = 14-25+ mmHg)

61
Q

In a Fontan circulation blood goes:

A

LV → aorta → organs

62
Q

That CVP propels blood

A

capillaries → veins → RA → lungs

63
Q

If PVR is high, the Fontan

A

cannot be performed.

 A small amount of resistance will exist across the lungs. (pressure drop)

64
Q

Hybrid Treatment (HLHS)

A

Hybrid Cath Lab/OR room
 Palliation to ensure survival  PDA stent
 Atrial Septal Stent (Balloon if needed first)  Bilateral PA Banding
 Remember: Balancing and controlling the pulmonary and systemic flow is of utmost importance on these children

65
Q

SUCCESS OF NORWOOD

A

75%.

66
Q

The overall success following the hemi-Fontan procedure (stage II)

A

approaches 95%.

67
Q

Success after completing the Fontan procedure (stage III)

A

90%.

68
Q

Among low-risk patients who undergo staged reconstruction or transplantation,

A

actuarial survival at 5 years is approximately 70%.

69
Q

What does that mean? Be careful with statistics.

A

 75% alive after stage I (at hospital discharge)  95% alive after stage II (at hospital discharge)  90% alive after stage III (at hospital discharge)
 This means:  .75 x .95 x .9 = 64% overall survival

70
Q

Ideal Post-op Blood Gases

A

 PaCO2:  pH:  PaO2:  SaO2:
35–45 mm Hg 7.35–7.40 30–45 mm Hg 70–85%
7.4 / 40 / 40 is key Hematocrit >40 % , SAO2 = 75%

71
Q

To much shunt flow ? BLOOD GASES

A

 PaCO2: 36  pH: 7.23  PaO2: 49  SaO2: 88%  BE: -7.8

72
Q

To little shunt flow ? ABG

A

 PaCO2: 48  pH: 7.19  PaO2: 23  SaO2: 58%  BE: -11.8

73
Q

CPB Considerations

A

3 Tough cases  Fragile OR and post-op course  May need ECMO  May need NOMO (ECMO with no oxygenator in line)  May need a VAD  Hemi- and Fontan are redo surgeries (femoral cannula?)

74
Q

 Due to the atretic aorta where are you going to cannulate for arterial? AND VENOUS HYPOTHERMIA CARDIOPLEGIA

A

 Arterial: Pulmonary artery (what?)
 Venous: Single atrial
 Hypothermia: DHCA (possibly antegrade cerebral/retrograde cerebral perfusion)
 Cardioplegia: One shot antegrade  Thru arterial cannula  Aortic root if possible

75
Q

PUMP RUN

A

Pump Run: On → cool: 20 min → XC/CP/arrest → warm: on 23 min → off CPB →MUF 10 min
 *(OnDHCA:letvenousexsanguinationoccurbeforeclampingthe venous line )
OR
On → cool: 20 min → Arrest/XC/CP → warm: on 23 min → off CPB→MUF 10 min

76
Q

 Typical times: FOR PUMP RUN

A

 CPB time = 43” XC time= 48 Arrest time= 45

77
Q

What considerations do you need to make when you circulatory arrest first, then give CP down the aortic cannula?

A

?

78
Q

Arterial and Venous Cannulation BDG

A

 Arterial: Neo-aorta  Venous: Single Atrial  Hypothermia: Moderate – continuous CPB  Cardioplegia: No cardioplegia
 An extra-cardiac Fontan will follow this procedure

79
Q

Arterial and Venous Cannulation Hemi Fontan

A

 Arterial: Neo-aorta  Venous: Single Atrial  Hypothermia: DHCA  Cardioplegia: With cardioplegia
 A lateral tunnel Fontan will follow this procedure

80
Q

Arterial and Venous Cannulation Fontan

A

 Arterial: Neo-aorta  Venous: Single atrial  Hypothermia: Mild  Cardioplegia: With or without cardioplegia

81
Q

CPB Notes

A

Physiology is tough with these kids  (think in terms of QP/Qs)
 Keep pump primed and ready  (you may only be off temporarily)
 Redo surgeries can take a while to get in  (be ready to use emergent femoral cannulation)

82
Q

And what if your patient can’t come off CPB?

A

ECMO NOMO Pediatric VAD

83
Q

Pediatric VADS

A

Mechanical circulatory support is expanding it’s role in congenital cardiac surgery.
 Pediatric impella is available  ECMO and centrifugal ventricular assist
devices are still the mainstay,  New pulsatile, para-corporeal VAD’s designed for
pediatrics are being utilized.
 In addition, several new, continuous flow devices are under development as fully implantable systems for adults, ultimately may be useful for pediatric patients.

84
Q

BELIN HEART DRIVEN BY

A

is a pneumatically driven, pulsatile para-corporeal device that can offer either LVAD, RVAD or (BIVAD) support.

85
Q

 The pump sizes are BERLIN HEART

A

0, 25, 30, 50 and 60 mls, meaning that it can be used to support any size of child from 3-100 kg.

86
Q

The LVAD drains blood from the

A

LV via a cannula inserted into the apex and returns it to the aorta

87
Q

The RVAD drains from the

A

RA and returns blood to the PA

88
Q

Notes on Pediatric VADS

A

 Berlin Heart has a limited center usage  VADS can be time consuming to the staff (perfusion
may have to be in-house or bedside)
 Other VADS are used with a BSA > 0.7
 Most Peds centers have ECMO staffs that already are made to staff 24/7

Pediatrics (14 decks)

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