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Cardiology > Congenital Heart Disease 1-3 > Flashcards

Congenital Heart Disease 1-3 Flashcards

1
Q

Define congenital heart disease

A

consists of structural abnormalities of the heart present, though not necessarily manifest, at birth

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2
Q

Approx. ____% of those born with a congenital heart disease have significant heart disease

A

-50%

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3
Q

Does congenital heart disease appear to have a genetic component?

A

-yes; if have 1 child with CHD, 2-4% others will; 10% of offspring of mothers with CHD have some form of CHD

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4
Q

3 main etological categories of CHD

A
  1. idiopathic in </ 86%, possible polygenic predisposition coupled with non-specific environmental factors
  2. Genetic ~12%; single gene and chromosomal anomalies
  3. Toxic and metabolic ~2% maternal exposure to drugs, known toxins, maternal infections and metabolic illnesses
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5
Q

3 general physiologic principles of ventricular failure

A
  1. exercise intolerance
  2. growth failure
  3. elevation of venous pressures: pulmonary edema, hepatomegaly
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6
Q

Left-to-right shunts are so named why? What do they result in, in terms of blood flow?

A
  • abnormal connections between systemic and pulmonary circulations in which blood flows from the systemic side (anatomic left) to the pulmonary side (anatomic right)
  • resulting in increased pulmonary blood flow and normal systemic blood flow
  • pulm:systemic >1
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7
Q

Why does blood flow left-to-right through these defects? In other words, how does blood “know” which way to flow through a given defect?

A

-blood flows downhill aka whichever path has lower resistance in downstream vasc bed or more compliant heart chamber depending on location of the defect

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8
Q

With small VSD, the amount of flow is limited primary by the _______. Furthermore, the defect itself may close during systole resulting in a _______.

A
  • size of the defect

- short systolic murmur on P/E

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9
Q

For large defects distal to AV valves, such as VSD and PDA, flow favors the _________. What occurs shortly after birth in these circuits?

A
  • flow favors the lower resistance pulmonary vascular bed
  • therefore as pulmonary vascular resistance falls after birth, L-to-R shunt increases causing increased pulmonary blood flow
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10
Q

T/F: With increased shunting in large VSD after birth, CO to brain decreases.

A

-false; homeostatic mechanisms (baroR) maintain systemic blood flow within normal limits irrespective of systemic venous pulm. vascular resistance ratios. Therefore, for practical purposes, only pulmonary blood flow varies with changes in resistance ratios

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11
Q

Hypertrophy pattern in large VSD

A
  • biventricular
  • volume load on LV (due to returning shunted blood from PA) and pressure load on RV due to defect being so large that the RV is essentially held to the systemic level of the LV
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12
Q

Heart sounds with large VSD

A
  • shunt occurs throughout systole and the turbulence at the defect itself results in a holosystolic murmur
  • increased pulmonary blood flow results in increased PV return and increased flow across mitral= mid-diastolic murmur
  • holosystolic murmur, mid-diastolic murmur
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13
Q

In some cases, long-standing high PBF results in _____________ .

A

-increased pulmonary vascular resistance (Eisenmenger reaction) in which L-R shunting decreases as shunting becomes bidirectional, finally resulting in R-L shunting and decreases PBF

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14
Q

For large defects proximal to AV valves (ASD), flow across the defect is determined by _________.

A
  • relative compliance of the 2 ventricles

- flow favors the more compliant ventricle which is usually the right ventricle (after birth at least)

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15
Q

3 things that determine compliance

A
  1. wall thickness
  2. chamber size
  3. composition of chamber wall (muscle vs fibrous tissue)
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16
Q

Why does it make sense that ASD symptoms manifest at 6-12 months vs 1-2 months with VSDs?

A
  • ASD depend on ventricular compliances and these change GRADUALLY over time due to downstream vascular resistance
  • so ASD takes 6-12 mos for shunting to truly occur vs VSD occurring in first 1-2 weeks of life
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17
Q

The volume load in ASD is on which locations?

A

-RA, RV, and PV

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18
Q

Heart sounds with ASD

A
  • systolic murmur across Pulm valve

- Diastolic murmur from increased flow across tricuspid valve

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19
Q

ASD and clinical conditions

A
  • no HF in childhood despite shunt
  • V load on RV causes hypertrophy and enlargement
  • may have failure to thrive
  • may develop Eisenmenger reaction in 3/4th decade
  • may develop HF in 6th decade or later
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20
Q

Patent ductus arteriosus (PDA) is a persistent patency of the normal fetal vessel that connects ______ to ________

A
  • pulmonary artery

- descending aorta

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21
Q

How is PDA shunting similar and different from VSD shunting?

A
  • similar: determined by size and relative pulmonary and systemic resistance
  • differs: flow occurs in both systole and diastole
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22
Q

For a given size communication, there will generally be more flow through a PDA or VSD, all other factors being equal.

A

-PDA

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23
Q

Physical findings of a PDA

A
  • continuous murmur: meaning a murmur that is predominantly systolic, but spills over into diastole (ie. continues past the second heart sound since the communication between systemic and pulmonary circum is distal to semilunar valves and therefore does not end with closure of those valves
  • bounding pulses due to a widened pulse pressure from “runoff” into lower resistance pulmonary vascular bed
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24
Q

PDA recap

A
  • continuous murmur (past S2) and bounding pulses
  • commonly seen in premature infants (since it is a normal fetal structural that typically closes at term)
  • may cause HF is large enough
  • bc of continuous flow throughout systole and diastole, may have larger L-R shunt than VSD
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25
Q

L-R Shunts disease manifestations

A
  • cardiac V overload: increased PBF, normal systemic BF
  • increased PA pressure due to high flow (defect distal to AV valves)
  • pressure overload to RV and consequent hypertrophy in cases with increased PA pressure
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26
Q

Complications of L-R shunts

A
  • CHF due to pressure and V overload or occassionally to V overload alone
  • Pulm vascular obstructive disease: increased, fixed elevation in PVR due to long-standing high P from high flow (Eisenmenger rxn)
  • Growth failure: may be only manifestation of HF
  • repeated bouts of pneumonia
  • bacterial endocarditis
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27
Q

Effects of Volume load on chambers

A
  • dilation: arrhythmia
  • hypertrophy
  • ventricular failure
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28
Q

Effects of Pressure load on chambers

A
  • hypertrophy
  • compliance changes, ventricles
  • ventricular failure
  • arrhythmia
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29
Q

Is hypertrophy usually greater in V or P overload?

A

-Pressure; but it is usually tolerated better than V overloads

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30
Q

Pulmonary edema due to elevation of venous pressures in ventricular failure and age

A
  • typically interstitial in infants

- alveolar in older children and adults (rales on PE)

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31
Q

Effects of increased pulmonary blood flow

A
  • dilation of pulmonary arteries: can lead to bronchiolar compression and pneumonias
  • pulmonary vascular disease (Eisenmenger reaction): rate of development will depend on P and O2 sat
32
Q

Effects of increased pulmonary artery pressure

A

-pulmonary vascular disease (Eisenmenger): initially meant as protective mechanism to protect down stream delicate capillaries from high P and blood flow

33
Q

Cyanosis and effects

A
  • decreased O2 delivery per RBC leading to metabolic acidosis
  • to try to recoup this loss, leads to polycythemia which can cause hyperviscosity, iron deficiency anemia (stroke risk)
  • exercise intolerance and acceleration pulmonary vascular obliteration if high PBF
34
Q

Categories of acyanotic CHD

A
  • septal defects: L-R shunts

- obstructive lesions

35
Q

4 general principles that affecting L-R shunts

A
  • anatomic location
  • defect size
  • vascular resistance
  • ventricular compliance
36
Q

3 examples of L-R shunts in acyanotic CHD

A
  • VSD
  • ASD
  • PDA
37
Q

What determines flow in large vs small VSD?

A
  • small: pressure difference between 2 ventricles and size

- big: both at same high P, so here is resistance

38
Q

Systemic flow vs pulmonary flow in large VSD

A
  • systemic: is maintained normally
  • pulm flow depends on ratio of pulm to systemic resistance
  • Ohm’s Law
39
Q

Why don’t babies with VSD have murmur at birth?

A
  • bc within 1st week of life, pulm VR is still very high and thus, very little shunting occurs
  • however, as this PVR drops with age, more blood is shunted and we here systolic murmur
40
Q

In a child with known large VSD, what does it mean if the systolic murmor goes away? What else happens to the heart sound?

A
  • if the systolic murmur goes away, that means that blood is no longer shunting L-R and this is due to increases Pulm vascular resistance from Eisenmenger reaction!!! Bad sign!
  • no sound splitting either of S2
  • flow R-L; RV hypertrophy; no S2 splitting; no murmur
41
Q

Murmurs of ASD

A
  • diastolic murmur from relative tricuspid stenosis due to increased flow
  • systolic PV murmur
  • no murmur from ASD itself since similar P
42
Q

3 examples of LH obstructive lesions in acyanotic CHD

A
  • aortic stenosis
  • coarctation of the aorta
  • hypoplastic left heart
43
Q

Describe the process of fetal coarctation

A
  • after heart has developed, there is a hit that reduces aortic outflow
  • remember, the brain is selfish and will make sure it gets enough blood, so to accomplish this, it causes a splitting opposite the ductus arteriosus to “steal” some of this blood away from descending aorta and divert it up to the brain
  • this splitting of the ductal flow induces a shelf opposite the entry site of the ductus. When the ductus closes postnatal, this shelf projects into aortic lumen causing narrowing
  • bc the ductus usually closes gradually beginning at the pulm artery end, the effect of the coarctation is gradual and collateral vessels from above it can connect to intercostals below affording continued, though less pulsatile flow to lower body
44
Q

What do many patients with fetal coarctation develop?

A
  • hypertension
  • stealing of blood from descending aorta makes kidney sense decreased pulsatility–shock state
  • renin release and upperbody HTN despite adequate flow to lower body
45
Q

Fetal hypoplastic arch

A

-another type of coarctation that occurs before cardiogensis is complete, unlike fetal discrete coarctation

46
Q

LH obstructive lesions disease manifestations

A
  • inc LAP
  • ventricular hypertrophy
  • ductal dependent: inc PBF when ductus is open, shock when ductus is closed
47
Q

LH obstructive lesions complications

A
  • CHF
  • Acidosis and circulatory collapse
  • sudden death
  • endocarditis
48
Q

2 types of coarctation

A
  1. discrete aka contraductal or adult type

2. tubular hypoplasia aka preductile or infantile type

49
Q

Both types of coarctation are thought to result from ___________.

A
  • decreased anterograde flow from the LV
  • in adult type: due to relatively minor intracardiac anomalies like BAV or such
  • in tubular hypoplasia form, due to major intracardiac abnormalities occurring during cardiogenesis, before the aortic arch is fully developed
50
Q

Describe the pathophysiology of tubular hypoplasia

A
  • dec LV output before cardiogenesis is complete, and thererfore, before the aortic arch is fully developed
  • therefore, instead of splitting of the ductal stream to compensate for the decreased LV output, the normal “excess” flow that would have traversed the aortic isthmus (to keep it patent) between arch vessels and ductus is diminished and the arch itself does not grow accordingly
  • since this arch hypoplasia is all prox. to the ductus, as soon as the ductus closes, even at the PA end, flow to lower body is severely compromised and circualtory collapses occurs early on aka hence why infantile! coarctation
51
Q

Review of coarctation of the aorta: definition and types

A
  • congenital narrowing of the aorta with 2 major forms:
    1. discrete type: presents with upper extremity HTN, prominent arm pulse with diminished or absent femoral pulses; may be asxs and may have murmur from collateral vessels over the back
    2. tubular hypoplasia: ductal dependent, typically presents with shock in early infancy coincident with closure of DA; usually have major intracardiac anomalies as well
52
Q

Severe and critical aortic stenosis presenting in the newborn period or first couple of months of life are virtually always due to _______. Complications?

A
  • unicuspid aortic valve
  • if severe, degree of obstruction from small orifice size and annular diameter causes the LV to hypertrophy which may impede coronary perfusion of subendo leading to arrhythmias or ischemic injury and HF
53
Q

In critical aortic stenosis, meaning that the LV cannot maintain adequate CO on its own and needs RV input via DA, the patient presents with ________ when the DA closes.

A

-circ collapse aka shock

54
Q

Unicuspid aortic valve typically presents in 1st year of life with ________ except for critical AS, which presents when and with what?

A
  • murmur

- if critical, in new born period with shock when DA closes

55
Q

What is the second most common cause of death from heart disease in the 1st month of life?

A

-hypoplastic LH syndrome

56
Q

Hypoplastic Left Heart Syndrome

A
  • characterized by underdevelopment of LV with normal relationship of great arteries to ventricles
  • MV and AV may be hypoplasic, stenotic, or atretic
  • rely on PA and DA for entire coronary and systemic circulation– uniformly fatal when DA closes
57
Q

4 traits of hypoplastic LH syndrome

A
  1. underdeveloped LV, MV, AV
  2. normal alignment of ventricles and great arteries
  3. ductal dependent systemic circulation
  4. presents with circulatory collapse in 1st week of life
58
Q

Cyanotic CHD classifications

A

-those that are pulmonary blood flow dependent vs those that are not

59
Q

PBF dependent Cyanosis

A
  • unlimited systemic-pulmonary mixing
  • cyanosis inversely proportional to PBF
  • PBF= TSR/TPR
  • usually have decreased pulmonary blood flow
60
Q

PBF in cyanotic CHD is most often reduced how? Give a classic ex

A
  • pulmonary outflow obstruction coupled with a septal defect permitting blood to “bypass” the lungs
  • classic example of this is Tetralogy of Fallot
61
Q

Defects in Tetralogy of Fallot

A

-combination of VSD and subpulmonary stenosis (below PV)

62
Q

In cyanotic CHD PBF dependent, systemic output and therefore venous return are essentially constant. The less pulmonary arterial flow and therefore PV return, the more _______.

A

-cyanosis

63
Q

Murmur in tetralogy of fallot

A
  • turbulent flow across PV causes systolic ejection murmur

- decreases as stenosis gets worse bc less blood crosses

64
Q

T/F: In CHD PBF cyanosis, R-L shunting amount determines cyanosis.

A

False; it is not simply the amount of R-L shunting that determines the degree of cyanosis but rather the total amount of PBF, regardless of the source!

65
Q

Hypertrophy in Tetralogy of fallot

A

-RVH due to large VSD

66
Q

What is the most common cyanotic heart defect?

A

tetralogy of fallot

67
Q

Compensation and complications of cyanotic PBF dependent CHD

A
  • compensatory polycythemia
  • CVA
  • brain abscess
  • growth failure
  • bilirubin gall stones
68
Q

Cyanotic CHD with PBF independent characterization

A
  • characterized by pulmonary and systemic circulations in parallel with limited mixing
  • level of cyanosis is indepent of amt of PBF but is instead determined by degree of mixing of systemic and pulmonary venous blood
69
Q

As a general rule, CCHD-PBF independent have what PBF

A
  • high PBF, but with little mixing

- the highly saturated pulm venous blood returns mainly to the PA, leaving the systemic side desaturated.

70
Q

Typical example of cyanotic CHD with PBF independence

A
  • complete transposition of the great arteries (TGF) in which atria and ventricles are normally connected but the aorta arises from the RV and the PA from the LV
  • essentially 2 nearly separate circulations
71
Q

What determines mixing in TGA with PFO or ASD?

A

-size of atrial communication and the relative compliances of the 2 ventricles

72
Q

Procedure to increase size of PFO in TGA. What is the definitive repair?

A
  • Balloon atrial septostomy via cath: tear thin septum primum portion of the atrial septum and create a large ASD without need for surgery
  • definitive repair of transposition involves either redirecting systemic and pulmonary venous return or arterial switch operation
73
Q

Complications of C-CHD-PBF independent

A
  • systemic hypoxia
  • polycythemia
  • CVA
  • brain abscess
  • growth failure
  • bacterial endocarditis
  • bilirubin gallstones!
  • CHF from high pulm blood flow lesions
  • accelerated development of pulm vascular obstructive disease from high PBF lesions
74
Q

What condition do you think of if young pts get blue after eating or exercise?

A

-Tetralogy of Fallot; decreases systemic resistance, so less PBF and therefore more cyanosis

75
Q

3 ways to decrease pulmonary blood flow?

A
  • PA stenosis
  • Pulm vascular resistance
  • PV obstruction
76
Q

Proof that C-CHD with PBF dependence is independent on R-L shunting and rather cyanosis is dependent upon PBF

A
  • Tetralogy of Fallot with pulmonary atresia
  • 100% shunting R-L however, duct between aorta and pulmonary arteries
  • this increases PBF, and pts can be seen to be quite pink!
77
Q

Ventricular compliance in TGA

A
  • mixing determined by SD size and ventricular compliance
  • recall in normal hearts, those linked with pulmonary circulation are thinner ventricles vs those linked to systemic (LV>RV). In these hearts, the LV is actually thinner bc this is the side linked to the pulmonary circulation! So, this is the mechanism of mixing! (1-2 weeks)

Cardiology (27 decks)

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