Cardiology Flashcards
What are most common causes of acyanotic congential heart disease?
- VSD
- ASD
- PDA
- Coarctation of the aorta
- Aortic valve stenosis
What are most common causes of cyanotic congenital heart disease?
Tetralogy of Fallot
Transposition of the great arteries
Tricuspid atresia
Why does fetal circulation have three shunts?
To bypass the lungs as they are not yet developed or functional
Name the three fetal shunts in fetal circulation
Ductus venosus
Foramen ovale
Ductus arteriosus
What is the function of fetal shunt: ductus venosus?
This shunt **connects the umbilical vein to the inferior vena cava **and allows blood to bypass the liver.
What is the function of fetal shunt: foramen ovale?
This shunt connects the right atrium with the left atrium so bypass the RV and pulmonary circulation
What is the function of fetal shunt: ductus arteriosus?
This shunt connects the pulmonary artery with the aorta and allows blood to bypass the pulmonary circulation
Describe what happens to the foramen ovale at birth.
Foramen ovale:
* baby takes first breath = expands the alveeoli
* this decreases pulmonary vascular resistance
* this causes a fall in pressure in the right atrium
* at this point, L atrial pressure is higher than R atrial pressure
* so this squashes the atrial septum, causing functional closure of the formaen ovale.
* this becomes sealed. Now called fossa ovalis
Describe what happens to the ductus arteriosus at birth.
Ductus arteriosus closure:
* prostaglandins are needed to keep DA open
* Increased oxygenation causes a drop in circulating prostaglandins
* This causes closure of the ductus arteriosus
* becomes ligamentum arteriosum
Describe what happens to the ductus venosus at birth.
Ductus venosus closure:
* immediately after birth the DV stops functioing because the umbilical cord is clamped
* therefore there is no flow in the umbilical veins
* The DV structurally closes a few days later, becoming the ligamentum venosum
What is the nitrogen washout test (aka hyperoxia test) in CHD?
from passmed on ‘cyanosis in the neonatal period’
This test is used to differentiate between cardiac and non-cardiac causes of cyanosis.
* infant is given 100% oxygen for 10mins
* after this, ABG is taken
* a pO2 of less than 15kPa = indicates cyanotic congenital heart disease
What is the initial management of cyanotic congenital heart disease?
passmed
Supportive care
Prostaglandin E1 e.g alprostadil
* this is used to maintain a patent ductus arteriosus in ductal-dependent congenital heart defect
* this can act as a holding measure until a definite Dx is made and surgical correction is preformed
- How many leaflets does normal aortic valve have?
- What is the role of the aortic valve?
- how does number of leaflets differ in a patient with aortic stenosis?
- Three leaflets
- Role: allow blood to flow from the LV into the aorta, but prevent blood from flowing back into the left ventricle.
- will have 1, 2, or 4 leaflets.
What is the presentation of aortic stenosis?
- if mild - can be asymptomatic, discovered as incidental murmer during routine examination
- if significant - can present with fatigue, SOB, dizziness, fainting.
- Symptoms are worse on exertion
- if severe - will present with HF within months of birth
Describe murmer heard in aortic stenosis?
Ejection systolic murmer
Heard loudest at the aortic area (2nd ICS, right sternal border)
Has crescendo-decrescendo character
Radiates to the carotids
What signs may be present on examination of a patient with aortic stenosis?
- Ejection systolic murmer heard loudest on the aortic area (2nd ICS, right sternal border) which is crescendo-decrescendo and radiates to the carotids
- Ejection click just before the murmer
- Palpable thrill during systole
- Slow rising pulse and narrow pulse pressure
What is gold standard investigation for diagnosing aortic stenosis?
Echocardiogram
How is aortic stenosis managed?
- It is a progressive condition that worsens over time so needs regular follow ups with echos, ECGs and exercise testing to monitor progression
- If aortic stenosis is significant, may need to restrict physical activities
Options for treating stenosis:
* Percutaneous balloon aortic valvoplasty
* Surgical aortic valvotomy
* Valve replacement
What are the complications of aortic stenosis?
- Left ventricular outflow tract obstruction
- Heart failure
- Ventricular arrhythmia
- Bacterial endocarditis
- Sudden death, often on exertion
- How many leaflests does normal pulmonary valve have?
- What is role of pulmonary valve?
- Describe pathophysiology of pulmonary valave stenosis?
- three leaflets
- prevent blood from returning to the heart.
- leaflets develop abnormally so can become fused or thickened. this causes a narrow opening between the RV and pulmonary artery = congenital pulm valve stenosis
What other conditions can pulonary stenosis be associated to?
Tetralogy of Fallot
William syndrome
Noonan syndrome
Congential rubella syndrome
How can pulmonary stenosis present?
- usually asymptomatic
- found incidentally during routine baby checks
- if significant - fatigue on exertion, SOB, dizziness, fainting
Describe the murmer heard in pumonary stenosis
Ejection systolic murmer heard loudest at the pulmonary area (2nd ICS, left sternal border)
What signs could a patient who has pulmonary stenosis present with?
- Ejection systolic murder heard loudest in the pulmonary area (2nd ICS, left sternal border)
- Palpable thrill in the pulmonary area
- Right ventricular heave due to RV hypertrophy
- Raised JVP with giant a waves
What is gold standard investigation for diagnosing pulmonary stenosis?
Echocardiogram
How is pulmonary stenosis managed?
Mild pulmonary stenosis:
* no intervention
* followed up with cardiologist - “watch and wait” approach
Symptomatic / significant stenosis:
* balloon valvuloplasty via a venous catheter = main treatment choice.
* if this is contraindicated / fails = open heart surgery
Describe balloon valvuloplasty via a venous catheter to a patient with pulmonary stenosis
Catheter is inserted under xray guidance into the femoral vein.
Goes through the IVC and right side of the heart to the pulmonary valve
Once here, dialte the valve by inflating the balloon.
What is an atrial septal defect?
a defect = a hole in the septum between the two atria
Describe the pathophysiology of atrial septal defects
(i.e.how does it happen?)
- during development, the left and right atria are connected.
- normally in the 4th week of gestation, the atrial septum is formed from two spearate endocardial cushions.
- these two walls grow downwards from the top of the heart and fuse with the endocardial cushion in the middle of the heart. This separates the atria.
- defects in these two walls = atrial septal defect.
How does an atrial septal defect affect blood flow in the heart?
- ASD leads to a shunt, where blood moves between both atria.
- pressure in the left atrium is higher than pressure in the right atrium - so blood moves from LA –> RA.
- So… blood continues to flow to the pulmonary vessels and the lungs to get oxygenated = pt is acyanotic.
- Increased flow to the right side causes the right side to become overloaded = right heart strain.
- R sided overload = R heart failure and pulmonary hypertension.
Initially, what is ASD:
* is it acyanotic?
or
* cyanotic?
Why?
Acyanotic
* blood moves from the L to R as LA pressure is higher than RA pressure.
* So blood still flows to the pulmonary vessels and lungs to get oxygenated and the patient does not become cyanotic.
What syndrome can ASD lead to?
Eisenmenger syndrome
How can ASD lead to Eisenmenger syndrome?
- R heart is becoming overloaded as blood is moving through the ASD via a L –> R shunt.
- This can lead to R sided overload and pulmonary hypertension.
- Pulmonary hypertension causes pulmonary pressure to become GREATER than systemic pressure.
- This reverses the L–> R shunt, so becomes a R –> L shunt across the ASD
- because of this blood bypasses the lungs and pt becomes cyanotic
= Eisenmenger syndrome
What are the types of atrial septal defects?
Ostium secondum
Patent foramen ovale
Ostium primum
(Also in TMP = sinus venosus defect and coronary sinus defect but these aren’t mentioned by Dr Tom)
Atrial septal defects
What is ostium secondum?
Where the septum secondum fails to fully close, leaving a hole in the wall.