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Semester 2 - CVS > 7. Congenital heart defects > Flashcards

7. Congenital heart defects Flashcards

1
Q

What are acyanotic heart defects?

A

Class of congenital heart defects in which blood is shunted from left side of the heart to the right side of the heart.

Deoxygenated blood does not enter systemic circulation.

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2
Q

What are cyanotic defects?

A

Class of congenital heart defects in which blood is shunted from the right side of the heart to the left side of the heart.

Deoxygenated blood enters the systemic circulation.

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3
Q

What are the different types of acyanotic defects and what are their incidence rates?

A
  • atrial septal defect (1 in 1500 live births)
  • potent foramen ovale (20% of population)
  • ventricular septal defect (1.5-3.5 per 1000 live births)
  • patent ductus arteriosus (1 in 2,500 to 5,000 live term births)
  • valve stenosis
  • coarctation of the aorta
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4
Q

Describe Left to right shunts

A

– Requires a hole !
– Blood from the left heart is returned to the
lungs instead of going to the body
– Increased lung blood flow by itself is not damaging, but increased pulmonary artery or pulmonary venous pressure is.

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5
Q

Describe Right to left shunts

A

– Requires a hole and distal obstruction !

– De-oxgenated blood bypasses the lungs

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6
Q

What are atrial septal defects?

A

Opening in the septum between the 2 atria persists following birth

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7
Q

What are the different types of atrial septal defects and which is most common?

A
  • ostium primum ASD: hole near the tricuspid valve between the right atria and ventricle
  • ostium secundum ASD: hole near the centre of the septum (most common type 50-70% all cases)
  • sinus venous ASD: hole near one of the 2 places where the vena cavae enter the right atrium (can be near SVC or IVC)
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8
Q

What can lead to an ostium secundum ASD?

A

This defect arises from inadequate formation of the septum secundum, excessive resorption of the septum primum, or a combination.

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9
Q

What are the haemodynamic effects of atrial septal defect?

A
  1. Increased pulmonary blood flow
  2. RV Volume overload
  3. Pulmonary hypertension is rare
  4. Eventual Right Heart Failure
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10
Q

Describe the flow of blood as a result of an ASD

A

As left atrial pressure is normally higher than right atrial pressure, flow will mainly be from left to right and there is no mixing of deoxygenated blood with the oxygenated blood being pumped around the systemic circulation.

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11
Q

What is a patent foramen ovale?

A

Failure of the foramen ovale to close properly after birth.

- failure of fusion of the 2 septa

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12
Q

What is the incidence rate of PFO?

A

20%

- most people never know they have it

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13
Q

What are possible complication of PFO?

A

Maybe a cause of paradoxical embolism leading to cerebrovascular accident (CVA) (i.e. stroke)

When thrombus in a systemic vein breaks loose, travels to the right atrium, then passes across the PFO to the left atrium if right-heart pressures are elevated, at least transiently (e.g., during a cough, sneeze, or Valsalva type maneuver), and then into the systemic arterial circulation.

The condition may play a role in migraine headaches and it increases the risk of stroke, transient ischemic attack and heart attack.

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14
Q

What are ventricular septal defects?

A

abnormal opening in the interventricular septum.

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15
Q

Where do VSD most commonly occur?

A

in the membranous portion of the septum, but can occur at any point in the wall

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16
Q

Which way will blood flow through a VSD and what determines the amount of blood flowing through?

A

Since left ventricular pressure is much higher than right, blood will flow from left to right, the amount of flow depending on the size of the lesion.

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17
Q

What are the haemodynamic effects of VSDs?

A
  1. Left to right shunt
  2. LV Volume overload
  3. Pulmonary Venous congestion
  4. Eventual pulmonary hypertension
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18
Q

Is VSD a cyanotic or an acyanotic defect?

A

VSD is an acyanotic defect, this is because there’s no mixing of deoxygenated and oxygenated blood being pumped around the systemic circulation.

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19
Q

What is patent ductus arteriosus?

A

Failure of the ductus arteriosus to close after birth.

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20
Q

Which way will blood flow in PDA?

A

From the aorta to the pulmonary trunk

- higher pressure in the aorta

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21
Q

What would you hear in a patient with PDA?

A

Continuous, machine-like murmur, heard best at the left subclavicular region. The murmur is present throughout the cardiac cycle because a pressure gradient exists between the aorta and pulmonary artery in both systole and diastole.

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22
Q

What is the ductus arteriosus?

A

The ductus arteriosus is a vessel that exists in the fetus to shunt blood from the pulmonary artery to the aorta before the lungs are functioning

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23
Q

What happens to the ductus arteriosus after birth?

A

This vessel should close shortly after birth as the pressure in the pulmonary artery drops following perfusion of the lungs.

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24
Q

Is PDA an cyanotic or cyanotic defect?

A

ASD is an acyanotic defect, this is because there’s no mixing of deoxygenated and oxygenated blood being pumped around the systemic circulation.

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25
Q

What is Eisenmenger syndrome?

A

Process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect causes pulmonary hypertension and eventual reversal of the shunt into a cyanotic right-to-left shunt. Can occur in severe VSD and in ductus arteriosus

Acyanotic → cyanotic

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26
Q

What is coarctation of the aorta?

A

Narrowing of the aortic lumen in the region of the ligamentum arteriosum (below the origin of the left subclavian artery)

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27
Q

What are the 2 classification of coarctation of the aorta?

A

Preductal:

  • before entrance of the ductus arteriosus
  • ductus arteriosus persists - PDA

Postductal:

  • after the entrance of the ductus arteriosus
  • ductus arteriosus obliterated
  • more common
28
Q

What are the haemodynamic effects of coarctation?

A
  • increases afterload

- can lead to left ventricular hypertrophy

29
Q

What is coarctation associated with?

A
  • most common associated cardiac abnormality is a bicuspid aortic valve.
  • Aortic coarctation often occurs in patients with Turner syndrome (45, XO).
30
Q

Blood flow to which regions are and are not compromised due to coarctation?

A

Because the vessels to the head and upper limbs usually emerge proximal to the coarctation, the blood supply to these regions is not compromised. However blood flow to the rest of the body is reduced.

31
Q

What are the classic clinical signs associated with coarctation?

A

Hypertension in the right arm concomitant with lowered blood pressure in the legs

  • right arm supplied by right subclavian artery
32
Q

What is the Effect of coarctation of the aorta on femoral pulses?

A

Due to the fact that not enough blood can get through the aorta to the rest of the body, it means that you’ll get weak pulses in the femoral arteries as well as arteries of the feet.

33
Q

Is the adult coarctation of the aorta an acyanotic or cyanotic defect?

A

It’s an acyanotic defect, this is because there’s no mixing of deoxygenated and oxygenated blood being pumped around the systemic circulation.

34
Q

What are the different types of cyanotic congenital heart defects and what are their incidence rates?

A
  • tetralogy of fallot (5 per 10,000 live births)
  • tricuspid atresia
  • transposition of the great arteries (40 per 100,000 live births)
  • hypoplastic left heart
35
Q

What is Tetralogy of Fallot?

A

Group of 4 lesions occurring together as the result
of a single developmental defect which places the outflow portion of the interventricular septum too far in the anterior and cephalad directions

36
Q

What are the 4 defects of Tetralogy of Fallot?

A
  • An overriding aorta
  • Ventricular septal defect (VSD)
  • Pulmonary stenosis
  • Right ventricular hypertrophy
37
Q

How does tetralogy of fallot result in cyanosis?

A

Pulmonary stenosis refers to the narrowing of the pulmonary valve which causes the development of fetal right ventricular hypertrophy as the right ventricle must operate at a higher pressure to pump blood through the pulmonary artery.

The increased pressure on the right side of the heart along with the VSD and overriding aorta allow right to left shunting and mixing of deoxygenated blood with the oxygenated blood going to the systemic circulation, resulting in cyanosis.

38
Q

What is overriding aorta?

A

An overriding aorta is a congenital heart defect where the aorta is positioned directly over a ventricular septal defect (VSD), instead of over the left ventricle.

39
Q

What is the Level of severity associated with in TOF?

A

The magnitude of the shunt and level of severity depend on the severity of the pulmonary stenosis.

40
Q

What is tricuspid atresia?

A

Lack of development of the tricuspid valve leaves no inlet to the right ventricle (no communication between right atria and right ventricle).This leads to a hypoplastic (undersized) or absent right ventricle.

41
Q

How is blood flow to the lungs maintained in patients with tricuspid atresia?

A

There must be a complete right to left shunt of all the blood returning to the right atrium to allow blood flow to the lungs.

  • ASD or PFO: allow shunt from right atria to left ventricle

and

  • VSD: allow blood into the right ventricle
    or
  • PDA: allow blood from the aorta into the PT.
42
Q

What effect does tricuspid atresia have on the rest of the body?

A

Tricuspid atresia means that the heart cannot properly oxygenate the rest of the blood in the body, so the body cells doesn’t have enough oxygen to survive.

43
Q

What is transposition of the great arteries?

A

Right ventricle is connected to the aorta and the left ventricle to the pulmonary trunk.

44
Q

How does TGA affect circulation?

A

Creates 2 unconnected parallel circuits

  • right side circulated deoxygenated blood continuously in systemic circulation
  • left side circulates oxygenated blood in pulmonary circulation
45
Q

How does TGA affect the neonate?

A

Extremely hypoxic, cyanotic neonate.

46
Q

Why is TGA compatible with life in utero?

A

Flow through the ductus arteriosus and foramen ovale allows communication between the two circulations.

47
Q

Describe circulation in a fetus with TGA.

A

Oxygenated fetal blood flows from the placenta through the umbilical vein to the right atrium, and then most of it travels into the left atrium through the foramen ovale. The oxygenated blood in the left atrium passes into the LV and is pumped out the pulmonary artery. Most of the pulmonary artery flow travels through the ductus arteriosus into the aorta, instead of the high-resistance pulmonary vessels, such that oxygen is provided to the developing tissues.

48
Q

How can TGA be treated in the short term after birth and then long term?

A

To increase the chances of survival, doctors have to keep the foramen ovale open artificially or remains patent naturally, this ensures that there’s a tunnel between the atria.
In the long term an operation has to be carried out to switch the pulmonary trunk and the aorta back to their correct positions.

49
Q

What is hypoplastic left heart syndrome?

A

Underdevelopment of the left ventricle and the aorta, usually resulting in an absent or nonfunctional left ventricle and hypoplasia of the ascending aorta.

50
Q

How does blood reach the systemic circulation in a patient with hypoplastic left heart syndrome?

A

An ASD or PFO is present
- left to right atrial shunt

Blood gets into the arch of the aorta via PDA

51
Q

What proportion of babies with Down’s syndrome have congenital heart defects?

A

40% - 50%

52
Q

Which congenital heart defects most commonly affect babies with Down’s Syndrome?

A

Atrioventricular septal defects

neural crest cells have abnormal migration patterns in patients with trisomy 21

53
Q

Is HLHS an acyanotic or a cyanotic defect?

A

there is a mixing of oxygenated blood from the left atrium and deoxygenated blood from the right atrium which flows through the PDA to the aorta so yes cyanosis.

After birth the ductus arteriosus begins to close and pulmonary vascular resistance decreases, blood flow through the ductus is restricted and flow to the lungs is increased, reducing oxygen delivery to the systemic circulation. This results in cyanosis and respiratory distress which eventually leads to cardiogenic shock and death.

54
Q

Why might the right ventricle have to pump harder in VSD?

A

left t right shunt, so more blood being pumped into pulmonary system which means the pressure in the pulmonary arteries increase leading to vascular remodeling increasing resistance in the vessels so that the right ventricle has to pump harder

55
Q

What can be heard during auscultation of a patient with ASD?

A

Extra blood being pumped to pulmonary circulation leads to a delayed closure of the pulmonary valve which can be heard as a splitting S2 sound and a systolic murmur in some cases

56
Q

What can be heard during auscultation of a patient with VSD?

A

Holosystolic murmur at lower left sternal border

57
Q

What can be heard during auscultation of a patient with patent ductus arteriosus?

A

Heard as a continuous murmur called Gibson’s murmur. Present in systole and diastole because pressure in aorta is always greater than pulmonary artery

58
Q

Why might a patent ductus arteriosus become a right to left shunt?

A

Later in life, due to increased pulmonary volume and pulmonary hypertension, blood might be shunted from right to left

59
Q

Why might Eisenmenger syndrome from a patent ductus arteriosus lead to cyanosis of only the lower extremities?

A

As the arterial branches of the upper extremities are upstream from the PDA so receive oxygenated blood from the left ventricle

60
Q

How is a HLHS diagnosed?

A

before birth - prenatal ultrasound

after birth - echocardiography

61
Q

How is a HLHS treated?

A
  • prostaglandin keeps ductus arteriosus open until surgery

- surgery to fix heart defect or heart transplant

62
Q

Describe infantile/ preductal coarctation

A
  • after aortic arch
  • before DA
  • PDA present
  • high pressure in aorta upstream of coarctation but low pressure downstream, even lower than pressure in pulmonary artery. Results in deoxygenated blood from PA going into aorta(right to left shunt) –> leads to lower extremity cyanosis
  • often doesn’t survive post neonatal period
63
Q

Describe adult/ postductal coarctation

A
  • no PDA
64
Q

What are the effects of adult coarctation of the aorta upstream and downstream of the coarctation?

A

upstream:

  • increased pressure in vessels leading to upper extremities and head - risk of berry aneurysms
  • aorta and aortic valve dilate - risk aortic dissection

downstream:

  • decreased pressure in vessels leading to lower extremities - weak pulse - claudication
  • decreased perfusion to kidneys - activation of renin-angiotensin-aldosterone system –> hypertension
65
Q

What is cyanosis?

A

A physical examination finding in which the skin appears dusky blue due to the presence of deoxygenated hemoglobin, which is dark red in color. This is in comparison to the normal pink color of skin caused by the bright red of oxygenated hemoglobin.

seen on lips, fingertips, toes

66
Q

if the symptoms of a TGA go unnoticed due to naturally present FO and PDA, what can happen?

A

Can lead to congestive heart failure as the left ventricle pumps for the lower pressure pulmonary circuit and right ventricle pumps for the higher pressure systemic circulation leading to atrophy of LV and hypertrophy of RV

Semester 2 - CVS (20 decks)

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