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S4 W9-12 Congenital Heart Disease > Tetralogy of Fallot > Flashcards

Tetralogy of Fallot Flashcards

1
Q

What is cyanotic congenital heart disease?

A
  • Cyanotic CHD occurs when deoxygenated blood enters systemic circulation due to R-L or bidirectional shunting or mal position of the great arteries
  • One of the most common causes of cyanosis in new-borns = cyanotic CHD
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2
Q

What is cyanosis?

A

Bluish colour of skin and mucous membrane due to insufficient blood oxygen

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3
Q

Most common cyanotic heart lesions?

A
  1. Tetralgy of Fallot
  2. Tricuspid Atresia
  3. Total Anomalous Pulmonary Venous Return (TAPVR)
  4. Transposition of Great Arteries (TGA)
  5. Truncus Arteriosus
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4
Q

What is Tetralogy of Fallot?

A
  • Cono-truncal-septal anomaly results when anterior and superior deviation of the outlet IVS
  • Leads to malalignment of the outlet ventricular septum as well as unequal division of ventricular outflow tracts and great arteries
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5
Q

What are the four cardiac abnormalities in TOF?

A
  1. Subaortic VSD (large mal-alignment VSD)
  2. Dilated, overriding aorta
  3. RVOTOB (narrowing and obstruction of RVOT)
  4. RVH
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6
Q

How does subaortic VSD occur in TOF?

A

Occurs as cono-truncal septum and trabecular and inlet septum do not line up and connect

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7
Q

How does dilated, overriding aorta occur in TOF?

A

Anterior displacement of mono-truncal septum leads to rightward shift of the aorta, so the aorta straddles VSD and opens over both RV and LV

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8
Q

How does RVOTOB occur in TOF?

A

Results from crowding of sub-pulmonary outflow by muscular and fibrous tissues of the abnormal outlet ventricular septum

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9
Q

What may RVOTOB be due to?

A
  1. Stenosis or hypoplasia of the PV
  2. Hypoplasia of MPA and/or MPA branches
  3. Combination of these
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10
Q

How does RVH occur in TOF?

A

Occurs as compensatory mechanism to increased RV pressure due to RVOTOB

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11
Q

Circulatory pathway in TOF?

A
  • Deoxygenated blood from IVC/SVC –> RA –> RV
  • From RV, blood ejected through stenotic PV, to lungs where it is oxygenated –> pulmonary veins –> LA –> LV –> aorta
  • Overriding aorta receives oxygenated blood from LV and deoxygenated blood from RV
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12
Q

Circulatory Pathway: What is the degree of cyanosis dependent on in TOF?

A
  • Degree of mixing dependent on RVOTOB
  • More severe obstruction, more blood delivered from RV –> aorta = greater degree of cyanosis
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13
Q

Variants of TOF?

A
  • TOF + pulmonary atresia
  • TOF + absent pulmonary valve
  • TOF + double outlet RV
  • TOF + AV canal defect
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14
Q

Associated lesions of TOF?

A
  • Right aortic arch
  • Coronary artery anomalies
  • ASD
  • Additional VSDs
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15
Q

Syndromes associated with TOF?

A
  • DiGeorge Syndrome
  • Down syndrome
  • Foetal Alcohol Syndrome
  • Goldenhar Syndrome
  • Holt-Oram Syndrome
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16
Q

Diagnosing TOF?

A
  • Diagnosed on echo by detecting the four associated abnormalities
  • Use of turbulent flow in RVOTOB, CW to identify PG across PV, and measurement of pulmonary annulus
17
Q

TOF Repair?

A
  1. Patch closure of VSD
  2. Relief of RVOTOB (achieved by RVOT widening via trans-annular patch)
18
Q

Role of Echo Post TOF Repair?

A
  • Residual VSDs
  • PR Severity
  • RVOT: aneurysms, obstruction
  • RV and LV; size and systolic function
  • Aortic root: progressive dilatation quite common
  • ? AR: AR can occur secondary to aortic root dilatation
19
Q

Assessing AR in TOF?

A
  • Colour jet area
  • P1/2t; intensity of jet compared with forward flow
  • PW abdominal aorta: looking for pan-diastolic flow reversal
  • PW descending thoracic aorta: looking for pan-diastolic flow reversal
20
Q

Post-op complications of TOF?

A
  1. RV failure
  2. Severe PR
  3. Persistent RVOTOB
21
Q

Post-Op Complications of TOF: RV Failure

A
  • RV almost always dilated with some degree of systolic dysfunction
  • RV Anterior-Posterior Diameter (APd): if RV diameter appears larger than LV diameter at level of papillary muscle in PSAX, RV considered severely dilated
  • CMR best for assessing RV post TOF repairs
  • RV strain can also be used
  • Global longitudinal peak systolic strain (GLPSS): average of 3 x septal and 3 x free wall segments
  • Longitudinal peak systolic strain (LPSS): average of 3 RV free wall segments only
22
Q

Post-Op Complications of TOF: Severe PR

A
  • Very common post TOF repair
  • Severe for ‘free’ PR can be easily missed as PR jet is low velocity, so PR flow appears laminar on CFI; PR duration may only appear in early diastole and be brief
23
Q

Severe PR Parameters?

A
  • Jet width/annulus ratio ≥ 70%
  • Dense jet, PHT < 100ms (due to increased RV diastolic pressure caused by PR into RV)
  • Early termination of PR flow
  • Diastolic flow reversal in PA branches
  • Dilated RV
24
Q

Significance of PR: Class 1?

A

PV replacement (surgical or percutaneous) for relief of symptoms is recommended for patients with repaired TOF and moderate or greater PR with cardiovascular symptoms not otherwise explained

25
Q

Significance of PR: Class 2a?

A

PV replacement (surgical or percutaneous) is reasonable for preservation of ventricular size and function in asymptomatic patients with repaired TOF and ventricular enlargement or dysfunction and moderate or greater PR

26
Q

Post-Op Complications of TOF: Persistent RVOT Obstruction

A
  • See congenital PS notes
  • Can see pulmonary bifurcation from SSN SAX by rotating to 3-4o’clock position
  • If a high TR velocity: search for RVOT or PA obstruction at some level
27
Q

PR slope and duration in severe PR?

A
  • Dependent on RV compliance
  • Steep PR slope and early termination of PR signal = marked increase in RVEDP
  • May occur with 1) severe PR or 2) restrictive RV physiology

S4 W9-12 Congenital Heart Disease (10 decks)

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