HLHS, HRHS, Single Ventricle Quiz Prep Flashcards
How is HLHS characterized?
hypoplasia or atresia of the mitral valve hypoplasia of the left ventricle aortic stenosis or atresia hypoplasia of the ascending aorta coarctation
Where is the ASD of HLHS syndrome located?
Normally located superiorly on the atrial septum; in rare cases may be restrictive or the atrial septum may be intact.
What must happen in patients with HLHS but no ASD?
Another egress for pulmonary venous blood form the left atrium must exist, such as a decompressing vertical vein
What is obligatory with HLHS? Why?
PDA, as this is the main pathway for systemic outflow, including coronary perfusion.
Where do systemic and pulmonary venous blood mix?
Right atrium; creates a mixture of desaturate and saturated blood due to the PDA
Describe the resistance in the heart in HLHS in the presence of a non-restrictive atrial communication?
Resistance through the pulmonary circuit will be less than the systemic circuit, and there will be significant pulmonary over-circulation, limiting the degree of cyanosis
What may occur in patients with significant pulmonary overcirculation?
CHF
Systemic hypoperfusion
Acidosis
Infants with a restrictive or intact atrial septum will be both _________ and _______.
Cyanotic and acidotic
What will coexist frequently in infants with a restrictive or intact atrial septum?
Pulmonary venous abnormalities will coexist, limiting the prognosis of these infants
What is required after birth to maintain systemic perfusion in patients with HLHS?
Initial stabilization with prostaglandins for ductal patency and induction of pulmonary hypertension by careful hypoventilation and occasionally sub-ambient oxygen delivery with nitrogen
What is required after initial stabilization to maintain systemic perfusion in patients with HLHS?
Staged surgical palliation or cardiac transplantation have been the treatment options for HLHS.
What is the staged surgical palliation for HLHS?
- Norwood Procedure or Sano Modificaiton
- Glenn or Hemi-Fontan procedure
- Culminating in the Fontan procedures
*Some novel transcatheter techniques for first and third stage of the palliation
Certain high risk patients with HLHS are not good candidates for staged surgical palliation, and while awaiting cardiac transplantation, investigators have looked into novel approaches to…..
limit the pulmonary vascular injury from unprotected pulmonary blood flow.
What derived as a treatment for HLHS?
Hybrid palliation for HLHS has been derived
HLHS Hybrid palliation for HLHS
Involves rstricting pulmonary blood flow, insuring unimpeded systemic output, and unrestricted pulmonary venous return.
HLHS Hybrid Palliation: Step 1
Surgical branch pulmonary artery banding, performed through an open sternotomy and without cardiopulmonary bypass. These pulmonary bands are to be removed at the second stage of palliation.
HLHS Hybrid Palliation: Step 2
Create unimpeded systemic cardiac output via the ductus arteriosus. Either self-expanding on balloon-expanded stents are placed in the ductus to insure its continued patency once prostaglandin E1 is discontinued.
What is really important about Hybrid palliation: step 2 HLHS tx?
cover the entire ductus with stent, as any residual ductal tissue will contract producing significant obstruction to systemic outflow. The stent may be delivered either from a transvenous approach, or from a direct insertion into the main pulmonary artery
HLHS Hybrid Palliation: Step 3
Relieve any obstruction to pulmonary venous return at the atrial septum; usually involves balloon septostomy
What might make balloon septostomy difficult in HLHS patients?
In patients with HLHS, the atrial septum may be unusually thick an the atrial septal defect in an unusually superior position
Why do some operators choose to place a stent across the atrial communication in HLHS?
Performing a static balloon dilation of the septum frequently doesn’t tear a large enough opening
Patients returning for the second stage palliation of HLHS following first stage hybrid palliation will require a __________.
“Comprehensive” Surgery- debanding of the branch pulmonary arteries, resection of the stented ductus arteriosus and reconstruction of hte neo-aortic outflow, atrial septectomy and construction of the cavo-pulmonary anastomosis.
Investigators at a few sites have also looked at using hte “comprehensive” second stage palliation to set up what?
The 3rd stage to be a transcatheter Fontan completion
Single Ventricle Physiology
Parallel circulations and complete mixing of systemic and pulmonary venous return
Palliation of SV
Performed via three stages with some variability in the initial stage procedure depending on degree of aortic outflow obstruction and amount of pulmonary blood flow
What is the definitive therapy for functionally univentricular hearts?
Some modification of the Fontan/Keutzer Procedure
Fontan/Kreutzer Procedure
Separation of the systemic and pulmonary circulations arranging them in series without the contribution of a sub-pulmonary ventricle. Venous blood flows directly to the lungs, then returning to the systemic ventricle
“Classic” Fontan Procedure
Right atrial appendage was anastomosed to the main pulmonary artery to direct blood flow from the superior and inferior vena cava into the pulmonary artery
Why is the classic Fontan procedure no longer performed?
Subsequent dilation of the right atrium resulting in severe atrial dysrhythmias and atrial thrombi for the current forms of the Fontan procedure, including extracardiac nad lateral tunnel total cavopulmonary connections
HRHS
underdevelopment of the right side structures of the heart, which means that the chambers, valves and related blood vessels on the right side of the heart are malformed. This malformation involves the pulmonary valve atresia which has not formed, a very small right ventricle, a small tricuspid valve and a small hypoplastic pulmonary artery. As the ventricle has failed to grow and develop the ventricles muscle structure is poor, so additional problems are encountered as the heart attempts to pump blood to the pulmonary valve for transfer to the lungs. The proper amount of blood pumped from the right atrium is not sufficient and this causes the blood to be not pumped efficiently to the lungs.
Norwood Procedure Goals (3)
- Amalgamation of the proximal main PA w/ aorta, and augmentation of the aortic arch in a fashion that insures unobstructed flow form the systemic ventricle to the aorta and unimpeded flow into the coronary arteries and allows for growth of all segments of the aorta
- Atrial septectomy (unobstructed pulmonary venous return to the systemic ventricle)
- Regulation of pulmonary BF- to allow normal development and maturation of the pulmonary vasculature in anticipation of an eventual Fontan procedure
Sano Modification
provides pulmonary blood flow by means of interposition of a conduit between the systemic ventricle and pulmonary artery in place of a modified Blalock-Taussig shunt
