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Cardiology > Cyanotic congenital heart defects > Flashcards

Cyanotic congenital heart defects Flashcards

1
Q

In TGA, what defects must be present to maintain circulation?

A

ASD, VSD, PDA, Foramen ovale

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2
Q

What are the clinical features of transposition?

A
  1. Cyanosis from birth
  2. CHF signs
  3. Effortless tachypnoea
  4. Single and loud S2
  5. No murmur in intact septum
    * 6. Hypoxia with acidosis- not responding to hyperoxitest.
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3
Q

What are the ECG findings in TGA?

A

Normal or RVH (upright T in V1 may be only abnormality after day 3)
BVH if VSD, PSA or Pulmonary vascular disease present

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4
Q

CXR findings in TGA?

A

Cardiomegaly with increased pulmonary vascularity

Egg shaped cardiac silhouette

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5
Q

Management of TGA?

A

PGE1 infusion
Atrial balloon septoplasty (Rashkind)
Corrective surgery within weeks of birth

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6
Q

Steps in managing a cyanotic neonate

A
  1. CXR (may reveal pulmonary cause)
  2. ECG
  3. ABG in room air (a high pCO2 suggests lung or CNS problems, a low pH seen in sepsis, shock or severe hypoxaemia)
  4. Hyperoxitest
  5. UA line: Differential between pre and post ductal suggests shunt
  6. PGE1
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7
Q

What are the duct dependant systemic circulations?

A

Coarctation of aorta
Hypoplastic left heart
Critical AS
Interrupted aortic arch

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8
Q

What are the duct dependant pulmonary circulations?

A 
TGA
Pulmonary atresia with/without VSD
Critical PS
TOF
Tricuspid atresia
TAPVD with obstruction
Ebstein's anomaly
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9
Q

What abnormalities are present in TOF?

A
  1. RVOTO
  2. VSD (large enough to equalize pressures in both ventricles)
  3. RVH (secondary to RVOTO)
  4. Overriding aorta (varies)
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10
Q

In TOF, what is the most common type of RVOTO?

A

Infundibular stenosis- 45%
Rarely at PV level-10%
Combo- 30%

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11
Q

What are the associations of TOF?

A

Downs
22q microdeletion syndrome (DiGeorge)
CHARGE
VACTERL

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12
Q

Examination findings in TOF?

A

Varying degrees of cyanosis, tachypnoea and clubbing
RV tap along left sternal edge, systolic thrill ULSE
Ejection click in the aorta
Single S2 (P2 too soft to hear)
Loud Ejection systolic murmur and mid-ULSE (PS). More severe obstruction, softer and shorter the murmur.
*Acyanotic form- VSD and infundibular murmur along LSE.

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13
Q

ECG findings in TOF?

A

RAD in cyanotic TOF, normal axis in acyanotic

RVH

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14
Q

CXR findings in cyanotic TOF?

A

Normal heart size or smaller than normal
Decreased lung vascular markings
Boot shaped heart

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15
Q

What is the natural history of TOF?

A
  1. Worsening cyanosis
  2. Polycythaemia secondary to cyanosis (relative iron deficiency states)
  3. Hypoxic spells
  4. Growth retardation
  5. Brain abscesses and CVAs rarely occur
  6. SBE occasional
  7. Aortic regurg
  8. Coagulopathy is late complication of chronic cyanosis
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16
Q

What are the characteristics of a tet spell?

A

Hyperpnoea, irritability, prolonged crying, increasing cyanosis, decreased intensity of murmur.
Peak incidence 2-4 months
Usually in morning after crying, feeding or poos.
Severe spells- limpness, convulsions, CVA and death

17
Q

What are the broad categories for the causes of cyanosis?

A
  1. Inadequate alveolar ventilation
  2. Desaturated blood bypassing effective alveolar units
  3. Increased deoxygenation in the capillaries
  4. Methaemoglobinaemia
18
Q

How to differentiate cardiac vs pulmonary cyanosis?

A

Hyperoxitest- Inhaling 100% O2 in the presence of a shunt will increase the concentration of oxygen in the blood but the corresponding saturation of the Hb-O2 dissociation curve is not proportionally increased.

19
Q

How does oxygen in plasma differ from Hb?

A

Hb is sigmoid, plasma is linear.

20
Q

How does fetal Hb differ from adults? and when is it reached

A

Greater affinity for O2, favouring the extraction of O2 from the maternal circulation, but slow to release into the tissues.
3 months

21
Q

What increases Hb’s affinity for oxygen?

A
  1. Alkalosis
  2. Hypothermia
  3. Decreased 2.3.DPG
  4. Decreased ATP
22
Q

What are the consequences and complications of cyanosis?

A
  1. Polycythaemia- bone marrow stimulated through Epo . Viscous blood exacerbates CHF
  2. Clubbing
  3. CNS- CVA and brain abscesses. Central venous thromboses.
  4. Bleeding disorders- Thrombocytopaenia, prolonged PTT
  5. Hypoxic spells and squatting
  6. Scoliosis
  7. Hyperuricaemia and gout
23
Q

What is the acidosis in cyanotic heart disease caused by? and the consequences

A

Low arterial oxygenation causes anaerobic glycolysis
Both detrimental to myocardial function, together with volume overload leads to CHF
Stimulate the carotid and cerebral chemoreceptors to increase RR

24
Q

How are persistent truncus arteriosis and single ventricle similar?

A
  1. Almost complete mixing of systemic and pulmonary blood
  2. Identical pressures in the ventricles
  3. Level of oxygen saturation in the systemic circulation is proportional to PBF.
25
Q

What determines the direction of shunting in TOF? and how are the differentiated clinically?

A

The severity of the RVOT obstruction.
Mild L->R, behave like VSD (acyanotic or pink TOF)
severe R->L.

26
Q

What role does hyperpnoea have in tet spells? What leads to it and what does it lead to

A
  • Increases the effectiveness of the thoracic pump increasing venous return.
  • Decreased pO2, increased pCO2, and acidosis stimulates the respiratory centre to increase RR
  • Since either SVR is decreased or the PVR is increased, this extra blood has no choice but to go into the systemic circulation
27
Q

How are tet spells treated?

A
  1. Knee-chest: decreases systemic flow
  2. Morphine: Suppresses respiratory centre and hyperpnoea
  3. NaHCO3: Fixes acidosis
  4. O2: Slightly improves SaO2
  5. Vasoconstrictors
  6. Ketamine: Increases SVR and sedates
  7. Propanolol:
  8. EDUCATE PARENTS!
28
Q

How is TOF treated?

A
  1. Recognize and treat hypoxic spells
  2. Propanolol while awaiting surgery
  3. Palliative shunt procedure (first few months)
  4. Corrective surgery (4-12 months)
29
Q

What are the indications of palliative shunt procedure in TOF? ie Blalock- Taussig

A
  1. Neonates with TOF and pulmonary atresia
  2. Hypoplastic pulmonary annulus requiring a transannular patch
  3. Hypoplastic PAs
  4. Unfavourable coronary anatomy
  5. Medically unmanageable hypoxic spells (younger than 4 months)
    6.
30
Q

What are the two types of pulmonary atresia? Complete pulmonary valve atresia +

A
  1. +/- VSD + PDA/multiple aortopulmonary collaterals (MAPCAs)
  2. No VSD, + PDA, hypoplastic right heart and good pulmonary arteries supplied by the duct. (Totally duct dependant)
31
Q

Clinical features of pulmonary atresia

A
  1. Cyanosis
  2. No anterior murmurs, posterior continuous murmurs from colats.
  3. Single S2
32
Q

ECG and CXR findings of pulmonary atresia?

A

RAH + RVH
Prominent RA, boot shape if VSD present
Pulmonary oligaemia

33
Q

Management of pulmonary atresia?

A
  • PGE2 if duct dependant
  • Pulmonary valvulotomy +/- BT shunt
  • Formation of systemic-pulmonary connection when older
  • Fontan operation if hypoplastic right heart
34
Q

What are the types of Total anamolous pulmonary venous drainage (TAPVD)?

A
  1. Supracardiac: 50%, right SVC via left vertical and innominate vein
  2. Cardiac: 20%, RA and coronary sinus
  3. Infracardiac: 20%, common pulmonary vein into IVC, portal vein, ductus venosus, or hepatic vein.
  4. Mixed: 10%
35
Q

What predisposes to pulmonary HTN in TAPVD?

A

Obstruction of pulmonary venous return

  1. Length of venous channels
  2. resistance from Hepatic sinusoids
36
Q

How does TAPVD without pulmonary venous obstruction present?

A
  1. CHF with FTT
  2. Recurrent chest infections
  3. Mild cyanosis
  4. Precordial bulge and hyperactive RV impulse
  5. Quadruple or quintuple rhythm
  6. Widely split and fixed S2
37
Q

TAPVD ECG and CXR?

A
  1. ECG: normal or RVH

2. Supracardiac- snowman. Infracardiac- small heart and hazy lungs

Cardiology (13 decks)

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