Management of Single Ventricle Physiology

1. Congenital Heart Defects:
Devon M. Fagel, JD
Pediatrics Clerkship, YSM III
Respiratory, Oncology & Research
November 30, 2010
Management of Single Ventricle Physiology

2. Overview
• Background: Embryology review of heart development
• Definitions: Anatomy of single-ventricle heart anomalies
• Procedures: Interventions to palliate/correct
pathophysiology
• Presentation: Cardiopulmonary management of patient
DN
• Conclusion: The Blalock-Taussig-Thomas collaboration

3. Embryology:
Everett & Lim, Congenital Heart Disease and Repair. Charlottesville, 2005
• Cardiac Tube: Single tube
twists rightward onto self
and begins pumping by 4w.
Truncus forms aorta & PA,
conus forms atria, bulbus
forms ventricle.
• Septum: A/V septate, form
respective valves. 22q11.2
deletion results in various
types of congenital defects.
• Right to Left Shunts: Fetal
lungs non-functional thus
cavae flow returns to RA
and diverted to LA by PFO.
Flow from PA diverted to
aorta via PDA.

4. Anatomy:
• Double Outlet Right Ventricle: Normally, PA which carries deoxygenated blood (blue) to lungs arises
from RV and aorta which carries oxygenated blood (red) to body arises from LV. In DORV, PA and
aorta arise from RV carrying mixed blood (purple) to both.
• Ventral Septal Defect: DORV always coincides with VSD which allows blood to pass between RV and
LV. Without VSD, oxygenated (though suboptimal) blood would not reach the aorta. Blood shunted
from left to right heart causing increase flow to lungs, leading to CHF.
• Interrupted Aortic Arch: Type B, interruption between left carotid and left subclavian occurs in 53% of
cases. Must rely on alternate path (PDA) for blood to reach lower body.
• Subaortic Stenosis: Narrowing of area below AV requiring LV to work harder to pump blood.
• Hypoplastic Left Heart Syndrome - Right heart is dominant providing most of systemic circulation.
Everett & Lim, Congenital Heart Disease and Repair. Charlottesville, 2005

5. Prenatal/Neonatal Interventions:
• Echocardiography: HLHS (right heart
dominant providing most of systemic
circulation) detected at 24w leading
to termination.
• Prostaglandin Therapy: Used at birth to
keep shunts patent, systemic circulation
remains viable.
• Presurgical Intervention: Given RV
overload and PHTN, goal to balance
pulmonary and systemic flow so that
pulmonary overcirculation will not
damage the lungs.
• ECMO: Cannulae placed in large vessels,
heparin added and pumped through
membrane oxygenator, removing CO2
and adding O2.
Everett & Lim, Congenital Heart Disease and Repair. Charlottesville, 2005

6. Palliation/Correction:
• Damus Kaye Stansel Procedure: Norwood procedure, initial palliation attempts to maximize systemic outflow while
balancing pulmonary outflow so as not to damage lungs. Begins with B-T shunt to establish systemic to pulmonary
connection between right brachiocephalic and RPA. Aorta reconstructed by excising distal PA and using homograph to
attach pulmonary trunk to aortic trunk thus isolating pulmonary artery branches from systemic flow.
• Glenn / Hemi-Fontan Procedure: Second procedure to separate right and left heart function to allow pressures and
oxygen levels to normalize. Normally right heart (low pressure) pumps blood to lungs and left heart (high pressure) to
body. Veins carry deoxygenated blood (SaO2 70%) while arteries carry fully oxygenated blood (SaO2 99%). In
congenital heart typical SaO2 levels around 85%. In 1st stage of Fontan, B-T shunt disconnected and PA is excised so
that all blood flow to body provided by dominant ventricle. SVC attached to RPA providing venous flow to lungs. In
second stage IVC is attached to RPA by tunneling through right atrium.
Yuan & Jing, Arch Cardiovasc Dis 102: 549-557, 2009

7. Norwood Procedure (Stage 1):
Yuan & Jing, Arch Cardiovasc Dis 102: 549-557, 2009

8. Presentation:
• Birth Hx: ex-40wks born to 34 yo G5P3A1LC2 mother with prenatal dx
of CHD. Declined karyotype during pregnancy. APGARs 7/8, initially
required several CPAP breaths but no chest compressions. SpO2 remained
in 80’s pransferred to NBSCU and then NICU
• Hospital Course: 10 m/o f with hx of double outlet right ventricle,
interrupted aortic arch, subaortic stenosis s/p Damus-Kay-Stansel and Glen
procedures. Post-op course complicated by chronic lt pleural effusion, s/p
lt upper lobectomy and plication of lt hemidiaphragm, ECMO, persistent
respiratory failure s/p tracheostomy, urosepsis, mediastinitis, and seizure
d/o due to IJ thrombosis and bilateral subdural hemorrhages.
• Recent Events: Broncoscopy showed diffuse bronchomalacia but patent lt
lower mainstem bronchus, CPAP titrated down from 12 to 5. Developed
Pseudomonas+ tracheitis and decompensated. Due to increased
tachycardia, agitation and WOB, continued on 0.5mg morphine q6, Ativan
0.5mg q4. Also found to have elevated LFTs and GGT. Recent cx show
CMV+.

9. Cardio/Pulmonary Management:
Photiadis et al., Eur J Cardiothorac Surg 29: 551-556, 2006
• Oxygen Saturation: Mathematical models suggest maximal systemic oxygen delivery occurs with Qp/Qs < 1.
However, optimal hemodynamic status and end-organ function thus higher survival correlate with Qp/Qs
ratio of 1.5. Ventilatory settings should be set to achieve an O2 saturation of 80-85%. This can be achieved
through FiO2.
• Ventricular Function: Digoxin, Lasix and Aldactone to support ventricular function. Check HR, edema and
strictly monitor I/Os.
• Anticoagulation: Given hx of IJ thrombosis and femoral vein occlusion. Check distal pulses, capillary refill
and temperature of extremities.
• Antibiotics: Given subaortic stenosis, pt at risk of bacterial infection. Conduct complete heart exam for
increase in murmur at LUSB.
Mastropietro and Tourner, NeoReviews 10: 239-244, 2009
Bradley et al., J Thorac Cardiovasc Surg 127: 473-480, 2004

10. Cardio/Pulmonary Imaging:
• Lt Basal Opacities: Lt lower lobe consolidation, lt pleural effusion obscuring
hemidiaphragm, likely atelectasis/fibrosis.
• Cardio/Pulmonary Anatomy: Transverse diameter of heart enlarged, pulmonary
vasculature prominent centrally.
• Foreign Objects: Tracheostomy tube, median sternotomy wires, mediastinal clips
and stents.

11. ID/Neuro/Dev Management:
• Tracheitis: Cx showed Pseudomonas/MRSA+.
• Transaminitis: Alk Phos 533 (80-380). GGT 369, trending down from 450. Normal US. Hep
panel, EBV, CMV sent showed CMV+. PCR quantification >200.
• Seizure Disorder: Check phenobarbital levels monthly.
• NeuroDevelopment: Given genetic abnormalities, bypass surgery, prolonged hospital stay and
vent/trach dependent, significant delays.
Sarajuuri et. al, Journal of Pediatrics 157: 414-420, 2010

12. Conclusion:
Blalock & Taussig, JAMA 128: 189-202, 1945
“The operations here reported were undertaken with the conviction that
even though the structure of the heart was grossly abnormal, it might be
possible to alter the course of the circulation in such a manner as to
lessen the cyanosis and resultant disability.”

13. Murphy & Cameron, JAMA 300: 328-330, 2008
“The Blalock-Taussig article foreshadowed areas of progress in the
treatment of patients with congenital heart disease by providing a
model for cooperation across disciplines (cardiac surgery, pediatric
cardiology and animal research) to make striking medical progress.”

14. Murphy & Cameron, JAMA 300: 328-330, 2008