PE Board- Single ventricles

What does the term single ventricle refer to?

A groups of severe congenital heart defects in which the heart functionally has only one pumping chamber

What are the effects of a single ventricle?

Significant mixing of deoxygenated blood with oxygenated blood in the body causing marked cyanosis

What communication between chambers/great arteries may be required to maintain pulmonary and systemic circulations?

PDA, ASD, VSD

What are examples of single ventricles?

HLHS, tricuspid atresia, Ebstein anomaly, DORV, DILV, AV canal

What is HLHS?

The LV is incapable of providing adequate systemic perfusion. Can be due to abnormalities like MS/M atresia, AS/A atresia, or hypoplastic arch

What is the most severe lesion that accounts for 20-25% of all mortality in infants w/ CHD?

HLHS

What are syndromes associated with HLHS?

Turners, Smith-Lemli-Opitz, Holt Oram, Jacobsen

What are symptoms of HLHS?

Low cardiac output: poor perfusion, tachycardia, acidosis, hypotension, weak pulses. Tachypnea and cyanosis at birth. Chest x-ray will reveal large heart with increased pulmonary vascular markings.

How can HLHS be divided by anatomical groups?

MS/AS, MS/Aortic atresia, MA/AA (worst one to have)

What are characteristics of AA/MA with intact IVS?

Valves have bright plate-like appearance, LV cavity may not be distinguishable or just a small slit, ascending aorta is very narrow due to no blood flow from the LV

What are the characteristics of AA/MS w/ intact IVS?

LV cavity is a little larger but myocardial wall is thickened, coronary artery abnormalities present in 30-50% of cases

What are the characteristics of AA/MA w/ VSD?

With a large VSD the LV cavity may be normal since blood enters through the defect. Wall thickness may be normal but a true normal LV cavity is only seen in 5% of patients. Due to AA, arch is small and flow perfusion is still from PDA.

What are characteristics of MS/AS?

LV cavity size ranges from moderately hypoplastic to borderline since both valves are patent but still taking into consideration the level of stenosis varies, ascending aorta and arch may be normal size with flow following normal pathway (depending on level of stenosis- if severe asc Ao may be dilated due to post stenotic dilation)

What is tricuspid atresia?

The complete absence of an opening between the RA and RV

What are symptoms of TA?

Varies depending on associated congenital anomalies (VSD, great artery relationships), most importantly is the complete mixture of systemic and pulmonary venous return to the LA (O2 sats will be low and no significant differences in SVC, IVC and RA blood samples).

Cyanosis at varying degrees, clubbing of fingers and toes, moderate resting hyperventilation, warm extremities

What happens to patients with TA as the pulmonary vascular resistance diminishes?

Symtoms of pulmonary over circulation occur and HF is likely to develop.

What are the classifications of TA?

Type 1:normal relation of great arteries (most common)

Type 2: D-transposition of great arteries

Type 3: malpositions of the great arteries other than D-transposition

Type 4: Truncus arteriosus

What is the anatomy of TA with no VSD?

No communicator into the RV at all, so only flow to the pulmonary arteries if from a PDA. PV may be severely stenotic or atretic, MPA sizes vary from small to normal size since the PDA is sending blood into the MPA and swirling around before being sent to the lungs.

What is the anatomy of TA with an unrestrictive VSD?

Due to communication from LV to RV the chamber is usually fairly developed. size of MPA is typically larger since blood flow is coming from the one systemic ventricle towards a lower pressure area.

What is the anatomy of TA with a restrictive VSD?

A small to medium size restrictive VSD will produce an RV of variable size but usually smaller. RVOT/PV may be small and narrow with stenosis. Pulmonary artery size are usually well developed due to PDA. 50% of patients born with TA have a moderate or severely restrictive VSD.

How do you define DILV?

Both AV valves communicate/send blood into one common chamber. Because of the univentricular AV connection, MV and TV cannot be distinguished (they’re called Left and Right AV Valves)

What is the most common form of single ventricle hearts?

DILV

What are symptoms of DILV?

Clinical features are determined by the presence or absence of pulmonary inflow obstruction (RVOT obstruction)

Without obstruction: demonstrate symptoms of typical large L-R shunting VSD (CHF secondary to other associated lesions, tachypnea, diaphorsis, hepatomegaly, failure to thrive.)

Arrhythmias/conduction abnormalities are common

What is the morphology of DILV?

The main ventricular cavity exhibits LV morphology, outlet chamber with morphological characteristics of RV attached, both AV valves are usually normal, TGA is frequently seen with aorta arising from hypoplastic RV and pulmonary artery coming off the main LV (normal great artery relationship in 30% of cases)

What is the pathophysiology of DILV?

All systemic and pulmonary venous circulation that returns via the RA & LA enter the single ventricle. This causes complete mixture of deoxygenated with oxygenated blood causing a reduction in systemic arterial saturation in all patients. Depending on PVR, mixed blood is then shunts to the area of lesser resistance

How do you define PA w/ intact IVS?

Hallmark is an atretic pulmonary valve.

What are the classifications of PA w/ intact IVS?

Type 1: PA and hypoplastic RV (has small abnormal TV, severe RVH, coronary artery fistula, RAE)

Type 2: PA & normal or enlarged right heart structures (severe TR, thin walled and dilated RV, massively enlarged RA, no significant coronary artery fistulae)

What medication is given to patients with critical PS and PA/ intact IVS?

Prostaglandin