Cardiology - Heart Shunts Flashcards
What are innocent murmurs?
AKA flow murmurs
Fast blood flow through heart during systole
What are the typical features of innocent murmurs?
Soft
Short
Systolic
Symptomless
Stressed
- Quieter when standing, only appears when child unwell or feverish
What features of murmurs would need further investigation and referral to a paediatric cardiologist?
- Murmur louder than 2/6
- Diastolic murmurs
- Louder on standing
- Failure to thrive
- Feeding difficulty
- Cyanosis or SOB
What investigations would you use to establish the cause of a murmur in children?
ECG
CXR
Echocardiogram
Which murmurs are pan-systolic and where are they best heard?
Mitral regurgitation
Mitral area, 5th ICS, mid-clavicular line
Tricuspid regurgitation
Tricuspid area, 5th ICS, left-sternal border
Ventricular septal defect
Left lower sternal border
Which murmurs are ejection-systolic and where are they best heard?
Aortic stenosis
Aortic area, 2nd ICS, right sternal border
Pulmonary stenosis
Pulmonary area, 2nd ICS, left sternal border
Hypertrophic obstructive cardiomyopathy
4th ICS, left sternal border
What causes splitting of the second heart sound?
Negative intra-thoracic pressure causes right side of the heart to fill faster as blood taken from venous system
Increased volume in RV causes it to take longer for RV to empty in systole
This causes a delay in the pulmonary valve closing
When pulmonary valve closes later than aortic valve, second heart sound is split
What are the signs of atrial septal defect?
- Mid-systolic, crescendo decrescendo murmur
- Loudest at upper left sternal border
- Fixed split second heart sound
What is a fixed split second heart sound?
Second heart sound does not change with inspiration and expiration
Blood flows from LA into RA
Increased volume in RV before pulmonary valve can close
Does not vary with respiration
What murmur is heard in patent ductus arteriosus?
Small may not cause any sounds
Large PDAs cause normal first heart sound with continuous crescendo-decrescendo machinery murmur
Can continue during second heart sound making the second harder to hear
What murmur is heard in tetralogy of fallot?
Ejection systolic, heard best in the pulmonary area 2nd ICS, left sternal border
This is due to the pulmonary stenosis
When does cyanotic heart disease occur?
When blood is able to bypass pulmonary circulation and lungs
Right-to-left shunt
What heart defects can cause a right-to-left shunt?
Ventricular septal defect
Atrial septal defect
Patent ductus arteriosus
Transposition of the great arteries
When does blood flow from the right to the left in a shunt?
If pulmonary pressure increases beyond systemic pressure causes increased RA pressure
LA pressure < RA pressure
Blood now flows from the right to the left - Eisenmenger syndrome
Why do patients with transposition of the great arteries always have cyanosis?
Right side of the heart directly pumps blood into aorta and systemic circulation
When does the ductus arteriosus stop working and when does it close?
1-3 days post birth
Seals completely 2-3 weeks into life
What infection causes PDA?
Rubella
What is a big key risk factor for PDA?
Prematurity
How can asymptomatic patients suddenly present during adulthood?
Heart failure signs
What is the pathophysiology in PDA?
Aorta Pa > Pulmonary vessel Pa
Blood flows from aorta to pulmonary artery
Left to right shunt
Increased pressure in pulmonary vessels causing pulmonary hypertension - right sided heart strain as RV struggles to contract against increased resistance
Pulmonary hypertension and right sided heart strain causes right ventricular hypertrophy
Increased blood flowing through pulmonary vessels and returning to left side of heart then causes left ventricular hypertrophy
How does PDA present?
- May have continuous crescendo-decrescendo machinery murmur
- SOB
- Difficulty feeding
- Poor weight gain
- LRTI
What investigations are used for PDA?
Echocardiogram
Doppler flow studies to assess size of left to right shunt
Echo also assesses effects on the ventricles
How are PDAs managed?
Monitored using echocardiograms until 1 year
After 1 year, highly unlikely PDA will close
Trans-catheter or surgical closer can be performed
When are patients with PDA treated before 1 year?
Evidence of heart failure or symptomatic
What is the pathophysiology of atrial-septal defects?
Septum grows downwards from top of the heart downwards towards endocardial cushion and fuse to separate atria
Forms Septum primum and Septum secondum
Defects in these septa causes atrial septal defects
Foramen ovale is present in septum secondum, closes after birth
What are the different types of atrial septal defects, most to least common?
1) Ostium secondum
Septum secondum
2) Patent foramen ovale
Foramen ovale
3) Ostium primum
Septum primum, AV valve defects, atrioventricular septal defect
What are the complications of atrial septal defects?
Stroke
AF or atrial flutter
Pulmonary hypertension and right sided heart failure
Eisenmenger syndrome
How can strokes occur in patients with ASD?
If a patient has a large DVT that breaks off
Usually will go to the right-side of the heart and enter the pulmonary circulation causing a PE
If there has been a life-long asymptomatic ASD, this embolus can enter the left side of the heart and travel to the brain causing a large stroke
How do ASDs present?
- Mid-systolic, crescendo-decrescendo murmur, heart loudest at upper left sternal border
- Fixed split second heart sound
- SOB
- Difficulty feeding
- Poor weight gain
- LRTIs
What causes fixed split second heart sound in ASDs?
LA Pa > Ra Pa
Blood flows from left to right
Increased volume in RV, takes longer for pulmonary valve to close during systole, causing a splitting sound
How are ASDs managed?
Referral to paediatric cardiologist
If small and asymptomatic, watchful waiting
Transvenous catheter closure (via femoral vein)
Open heart surgery
How are ASDs managed in adults?
Anticoagulants e.g. aspirin, warfarin and NOACs
To reduce clot and stroke risk
What conditions are VSDs associated with commonly?
Down’s syndrome
Turner’s syndrome
Why don’t patients with VSD become cyanotic?
LV Pa > RV Pa
Blood flows from left to right
What does a left to right shunt lead to?
Right sided overload
Right heart failure
Pulmonary hypertension
What can happen after a long period of time in VSDs?
Pulmonary hypertension
Pressure in right side of the heart becomes greater than life
Blood shunted from right to left, leading to cyanosis
How do VSDs present?
Poor feeding
Dyspnoea
Tachynpoea
Failure to thrive
Can be picked up on antenatal scans or if a murmur is heard during new-born baby check
What murmur do patients with VSD typically have?
Pan-systolic, heard at left lower sternal border
3rd and 4th ICS
Systolic thrill on palpation
How are VSDs treated?
Dealt with by paediatric cardiologist
Small VSDs with no symptoms watched over time, they can close spontaneously
Transvenous catheter closure via femoral vein
Open heart surgery
What should be given during surgical procedures to patients with VSDs?
Antibiotic prophylaxis
Higher risk of infective endocarditis
When does Eisenmenger syndrome occur?
When blood flows from the right to the left of the heart
What lesions can cause Eisenmenger syndrome?
Atrial septal defect
Ventricular septal defect
Patent ductus arteriosus
How long does it take Eisenmenger syndrome to develop?
1-2 years with large shunts
Adulthood with small shunts
Develops more quickly during pregnancy, so women with “hole in the heart” need regular echos and close monitoring
What is the pathophysiology of Eisenmenger syndrome?
In shunt defects pressure in the left side of the heart is higher than the right
Blood flows from the left to the right
Over time extra blood flowing to the right side and lungs increases the pressure in the pulmonary vessels causing pulmonary hypertension
When pulmonary pressure exceeds systemic pressure blood flows from the right to the left, deoxygenated blood enters systemic circulation causing cyanosis
What does cyanosis lead to?
Reduced oxygen saturation of the blood
Bone marrow produces more RBCs and Hb to increase oxygen capacity of the blood
This causes polycythaemia, leading to a plethoric complexion
What are patients with polycythaemia more susceptible to?
Blood clots
Higher concentration of RBCs and Hb makes the blood more viscous
What are the examination findings associated with pulmonary hypertension?
Right ventricular heave- RV contracts forcefully against increased pressure in lungs
Loud P2- forceful shutting of pulmonary valve
Raised JVP
Peripheral oedema
What are the signs of right to left shunting or chronic hypoxia?
Cyanosis
Clubbing
Dyspnoea
Plethoric complexion
What is the prognosis of Eisenmenger syndrome?
Reduced life expectancy by 20 years
Main causes of death :
- Heart failure
- Infection
- Thromboembolism
- Haemorrhage
Mortality up to 50% in pregnancy
How is Eisenmenger syndrome managed?
Corrected surgically to prevent development
Once pulmonary pressure high enough, not possible to reverse it medically
Definitive treatment is heart-lung transplant, high mortality
- Oxygen management- symptoms only, does not affect outcome
- Sildenafil for pulmonary hypertension
- Treat arrhythmias
- Venesection for polycythaemia
- Anticoagulation for thrombosis
- Prophylactic abx for infective endocarditis
