Cardiology: CoA; VSD; PDA Flashcards
Describe the pathophysiology of CoA [2]
Co-arctation of the aorta causes an interruption of blood flow and impedes forward blood flow from the aorta.
This increases resistance (increasing afterflow), making LV bigger
- There is increased pressure proximal to the narrowing and decreased pressure distal to the narrowing.
Describe the presentation of CoA with the following:
- NIPE [3]
- Infancy [5]
- Sx that develop over time [3]
NIPE
- Weakened femoral pulse
- Increased pressure in the limbs supplied by vessels proximal to the narrowing (e.g., arms)
- Reduced pressure in the limbs supplied by vessels distal to the narrowing (e.g., legs)
Other signs in infancy (depending on the severity):
* Raised respiratory rate
* Increased work of breathing
* Poor feeding
* Heart failure
* Shock
Additional signs may develop over time:
* Left ventricular heave due to left ventricular hypertrophy
* Underdeveloped left arm where there is reduced flow to the left subclavian artery
* Underdevelopment of the legs
Which diseases is coarctation of the aorta associated with? [4]
Turner’s syndrome
bicuspid aortic valve
berry aneurysms
neurofibromatosis
NB - more common in males despite Turner’s
Describe the management of coarctation of the aorta [2]
IV prostaglandins are used in neonates to maintain a patent ductus arteriosus to allow adequate circulation until it is possible to attempt corrective surgery.
- IV prostaglandins ‘prop’ the door open
Describe the murmur heard in CoA [1]
Harsh systolic murmur heard over back
- Coarctation can produce a systolic murmur heard below the left clavicle and left scapula.
What is this CXR sign seen in CoA? [1]
Explain what’s going on [1]
Inferior rib notching - result of compensatory dilatation of intercostal arterires
What is important to note for follow up of CoA patients? [1]
HTN may persist throuhgout life
The ductus arteriosus connects the pulmonary artery with the aorta, allowing blood to bypass the lungs. It usually stops functioning within three days of birth and closes entirely within the first three weeks of life when prostaglandin E2 falls
- Patent ductus arteriosus (PDA) occurs when it fails to close after birth. The reasons it fails to close are unclear.
What underlies the pathophysiology of VSD? [1]
Disruptions in normal cardiogenesis during embryonic development. Specifically, faulty endocardial cushion formation or incomplete muscular septum growth often underlies VSD formation.
Describe how a VSD disrupts cardiac haemodynamics
Creates a left-to-right shunt due to higher pressures in the left ventricle compared to the right
- Consequently, oxygenated blood from the left ventricle is pushed into the right ventricle instead of being ejected into systemic circulation via the aorta
This abnormal shunting increases pulmonary blood flow and leads to volume overload on both right-sided heart chambers. Over time, this may cause hypertrophy and dilation of these chambers as they adapt to increased workload.
Over time, chronic left-to-right shunting can lead to pulmonary hypertension. This is due to increased pulmonary vascular resistance as the lung vasculature attempts to cope with excess blood volume
What is meant by Eisenmenger’s syndrome and what is the clinical significance? [2]
Over time, chronic left-to-right shunting can lead to pulmonary hypertension. This is due to increased pulmonary vascular resistance as the lung vasculature attempts to cope with excess blood volume. When severe, this may result in a reversal of the shunt (right-to-left)
- leads to desaturated blood being pumped into systemic circulation, causing cyanosis and further exacerbating symptoms.
- Additionally, it increases the risk of endocarditis and brain abscesses due to paradoxical emboli.
What are the different types of VSD with regards to morphology? [2]
Singular defect: Only one hole present in the ventricular septum.
Swiss cheese defect: Multiple small defects present in the muscular septum, resembling a Swiss cheese appearance. More challenging to manage due to potential for multiple shunts.
What are the four types of VSD with regards to their anatomical location? [4]
Perimembranous VSD:
- Most common type, located at the junction of the membranous and muscular septum. Often associated with conduction abnormalities.
Muscular VSD:
- Located in the muscular part of the interventricular septum. Can be further subdivided into trabecular, inlet or outlet types.
Doubly committed subarterial (supracristal) VSD:
- Located beneath both semilunar valves. High risk for progression to aortic regurgitation due to proximity to aortic valve.
Inlet (atrioventricular canal) VSD:
- Located close to tricuspid and mitral valves. Often seen in conjunction with atrioventricular canal defects.
What are the clinical features of VSD?
Murmur:
- A pan-systolic murmur is frequently noted at the left lower sternal border, radiating to the right lower sternal edge.
- due to turbulent blood flow from the left ventricle into the right ventricle through the septal defect.
Failure to Thrive:
- In cases where VSD is large and uncorrected, infants may present with growth retardation or failure to thrive. This can be attributed to increased metabolic demand and decreased oral intake due to tiring easily during feeds.
Pulmonary Overcirculation:
- Symptoms such as recurrent chest infections and exertional dyspnoea may be observed due to increased pulmonary blood flow leading to pulmonary overcirculation.
Cyanosis:
- Although less common, cyanosis can occur if there is a significant right-to-left shunt caused by pulmonary hypertension (Eisenmenger syndrome).
How would you differentiate the. murmur heard in ASD vs VSD? [3]
ASDs typically present with a softer systolic ejection murmur compared to the harsh holosystolic murmur characteristic of VSDs.
The murmur in ASD is best heard at the upper left sternal border, while VSD’s murmur is most prominent at the lower left sternal border.
Patients with ASD often exhibit wide and fixed splitting of S2, which is not seen in VSD.
What are potential complications of VSD? [3]
Potential Complications
Infective Endocarditis:
- Patients with VSD are at higher risk for developing infective endocarditis. It’s important that these patients receive appropriate prophylaxis when undergoing procedures that carry a risk of bacteraemia
.
Eisenmenger Syndrome
- Long-standing untreated VSD can lead to irreversible pulmonary hypertension (Eisenmenger syndrome), which eventually results in cyanosis and right heart failure.
Arrhythmias:
- VSD can predispose to the development of arrhythmias, particularly ventricular arrhythmias, due to the structural abnormalities and altered haemodynamics of the heart.
How would you differentiate the. murmur heard in PDA vs VSD? [3]
PDA classically presents with a continuous, ‘machinery’ murmur that contrasts the holosystolic murmur found in VSD.
The murmur in PDA is best heard at the upper left sternal border or infraclavicular area, differing from the location for VSD.
In contrast to VSD, bounding peripheral pulses and wide pulse pressure are distinctive features for PDA due to increased left-to-right shunting.
Describe the different managment options for VSD [+]
Medical Management
* In asymptomatic patients with small defects, conservative management with regular follow-up to monitor for any signs of heart failure or pulmonary hypertension is recommended.
* For symptomatic infants presenting with failure to thrive or recurrent respiratory infections, initial medical therapy includes diuretics, afterload reducers, and digoxin to control symptoms of congestive heart failure.
Interventional Cardiac Catheterisation
- This is a less invasive alternative to surgery for selected patients. It involves the placement of an occluder device via a catheter inserted through a vein or artery. This method may be considered in muscular or post-infarction VSDs.
Surgical Repair
Surgery remains the definitive treatment for larger defects causing significant left-to-right shunt, leading to volume overload and resultant cardiac enlargement.
- Early surgical intervention before development of irreversible pulmonary hypertension is vital.
- The procedure typically involves patch closure under cardiopulmonary bypass. Post-operative care in a specialist paediatric cardiac intensive care unit is required following surgery.
Patients with VSD need long term follow up because of risk of which complications? [+]
All patients with a history of VSD require long-term follow-up as they are at risk of developing complications such as arrhythmias, endocarditis, or reoccurrence of the defect. The frequency of follow-ups will depend on the patient’s age, size of the defect, presence of residual defects or associated anomalies.
What are the potenital cardiac complications of VSD? [5]
Cardiac Complications:
* Eisenmenger Syndrome: Chronic left-to-right shunting in large, uncorrected VSDs can result in pulmonary hypertension. Over time, this may cause a reversal of the shunt direction into right-to-left, leading to cyanosis and Eisenmenger syndrome.
- Heart Failure: Large defects may cause significant volume overload on the left side of the heart, leading to dilated cardiomyopathy and congestive heart failure.
- Endocarditis: Patients with VSD are at increased risk for infective endocarditis. Prophylaxis is usually recommended during certain dental or surgical procedures.
- Pulmonary Hypertension: Long-standing increased blood flow through the lungs due to left-to-right shunting can lead to vascular remodelling and pulmonary hypertension.
- Aortic Regurgitation: In membranous VSDs located near the aortic valve, there’s an increased risk for developing aortic regurgitation due to prolapse of an aortic cusp into the defect. This complication is more common in adults with undiagnosed or untreated VSDs.
Why might VSD increase the risk of ventricular arrhythmias? [1]
Rhythm Disturbances:
Ventricular arrhythmias may develop secondary to myocardial scarring from previous surgical repair or from chronic volume overload.
Atrioventricular block may also occur, especially after surgical repair involving the septum.
Describe the pathophysiology of PDA
TOM TIP: Causes of a pan-systolic murmur [3]
TOM TIP: Causes of a pan-systolic murmur: VSDs, mitral regurgitation and tricuspid regurgitation.
What is the use for ductus arteriosus during p
Prostaglandin E2 (produced by the placenta) keeps the ductus arteriosus open during pregnancy. Prostaglandin E2 falls following birth, resulting in the closure of the ductus arteriosus.
The pressure in the aorta is higher than in the pulmonary vessels. Therefore, blood flows across a PDA from the aorta to the pulmonary artery. This is a left-to-right shunt, where blood from the left side of the heart crosses to the right-sided circulation and lungs.
Additional blood creates more pressure in the pulmonary vessels (pulmonary hypertension), leading to strain on the right ventricle. Pulmonary hypertension and right-sided heart strain lead to right ventricular hypertrophy.
The increased blood volume returning to the left side of the heart leads to left ventricular hypertrophy.
Describe the presentation of PDA
- Include cardiac sx (including murmur) [4]
- other features [3]
A small patent ductus arteriosus may not have any abnormal heart sounds.
Larger PDAs cause a continuous crescendo-decrescendo “machinery” murmur, heard loudest below the clavicle. There is a normal first heart sound (S1), but the second heart sound (S2) may be difficult to hear over the murmur.
It may also present with symptoms of:
* Shortness of breath
* Difficulty feeding
* Poor weight gain
* Lower respiratory tract infections
Cardiac Sx:
* heaving apex beat
* large volume, bounding, collapsing pulse
* left subclavicular thrill
* wide pulse pressure
What is the managment of PDA in pre-term infants
most centres now recommend initial expectant supportive care rather than early pharmacologic therapy as spontaneous closure often occurs
if hemodynamically significant ΡDA remains or the infant remains ventilator dependent after one week of age then pharmacological closure is generally recommended:
* ibuprofen, indomethacin or paracetamol works to inhibit prostaglandin synthesis
* given to the infant, not to the mother in the antenatal period
* closes the connection in the majority of cases
* indomethacin use is declining due to increased side-effect profile compared to other drugs
What are the indications for closure of PD in term infants / children? [3]
moderate or large ΡDA
prior episode of endocarditis
small audible PDΑ
What is the technique for closing PDA in term infants / children? [1]
technique: transcatheter ΡDA closure rather than pharmacological therapy (ibuprofen/indomethacin) which is not effective in term infants
