CV Disorders

Question 1

Define heart failure

Answer 1

1. Heart unable to maintain adequate circulation for metabolic requirements of body
2. Preserved ejection fraction (HFpEF): EF ≥ 50%, ↓ diastolic function
3. Reduced ejection fraction (HFrEF): EF ≥ 40%, ↓ systolic function

Question 2

What is the underlying cause of heart failure?

Answer 2

Secondary to cardiac damage (ischaemia, myopathy), hypertension, valve disease

Question 3

What is a sign of heart failure?

Answer 3

Exertional dyspnoea

Question 4

What tests are done to diagnose heart failure?

Answer 4

Blood test: elevated brain natriuretic peptide (BNP)

Chest X-ray: cardiomegaly

Question 5

What are the treatment options for heart failure?

Answer 5

Drugs that reduce the exertional pressure on the heart

Question 6

Describe the pathophysiology of heart failure

Answer 6

Two types of heart failure. Systolic failure is where there is a reduced ejection fraction as a result of the muscle cells in the heart being weakened and hence unable to pump as forcefully since muscle is dilated. Diastolic heart failure is where ejection fraction is preserved but the ventricular walls stiffen and so area through which blood can flow is reduced.

Question 7

What does an ECG trace for heart failure look like?

Answer 7

Enlarged QRS complex due to increased muscle mass in the heart and hence larger electrical current generation. However, not always found in heart failure.

Question 8

How is atrial arrhythmia defined?

Answer 8

1. Atrial fibrillation (AF): Disorganised electric activity and contraction
2. Wolff-Parkinson-White (WPW): Syndrome causing tachycardia & abnormal cardiac electrical conductance

Question 9

What is the underlying cause of atrial arrhythmia?

Answer 9

AF: Spontaneously active cells throughout the atria.
WPW: additional accessory conduction pathway (the bundle of Kent) between the atria and ventricles.

Question 10

What is a sign of atrial arrhythmia?

Answer 10

Palpitations & chest pain

Question 11

What are the ECG findings in a case of atrial arrhythmia?

Answer 11

AF: Absent p-waves & ‘irregularly irregular’ rhythm.
WPW: QRS pre-excitation & biphasic/ inverted T-wave of ECG

Question 12

What are the treatment options for atrial arrhythmias?

Answer 12

AF: strategies to maintain sinus (e.g. cardioversion, anti-arrhythmics, catheter ablation)
WPW: benign, no treatment required

Question 13

Describe pathophysiology of atrial fibrillation

Answer 13

Caused by spontaneous and aberrant electrical currents in the atria caused by excitiation of pacemaker cells which have developed in regions outside the SA and AV nodes. Hence this uncoordinated activity prevents the smooth passage of electrical current from SA node to AV node resulting in absence of P wave.

Question 14

Describe pathophysiology of Wolff-Parkinson White syndrome

Answer 14

Can be classified as a conduction disorder as involves development of an accessory pathway. Hence, this accessory pathway causes a pre-excitation of the QRS complex and prevents current from solely going through AV node, providing additional pathway for current. Biphasic T-wave is due to this current being stopped by the AV node while repolarisation of ventricles occurs but a simultaneous depolarisation also occurs.

Question 15

What are the different types of conduction block?

Answer 15

First-degree block: slowing down of conduction through AV node
Second-degree block: reduced transmission of signal from atria to ventricles
Third-degree block: complete block of current from atria to ventricles

Question 16

What are the underlying causes of a conduction block?

Answer 16

Damage (fibrosis, calcification, necrosis) to the conduction system (AV node or His Purkinje system)

Question 17

What are the ECG findings in a case of conduction block?

Answer 17

1. First-degree block: increased P-R interval
2. Second-degree block: increased P-R interval or ‘missing’ QRS complexes, depending on type of block
3. Third-degree block: p-waves not followed by QRS complexes

Question 18

What are treatment options for a conduction block?

Answer 18

Discontinuation of AV-blocking drugs (e.g. beta-blockers, calcium channel blockers) or pacemaker implantation in severe cases.

Question 19

Describe the pathophysiology of the different heart blocks

Answer 19

1. First degree block: Primarily due to blockage at AV node where current can’t progress through the AV node and hence current slowed. This results in a long PR interval.
2. Second degree block: Blockage of conduction pathways and node so get a missing QRS complex. Number of QRS complexes missed depends on the type of block. Here current is stopped rather than slowed.
3. Third degree block: Most serious and medical emergency. Current not at all transmitted to ventricles due to blockage of pacemaker currents and hence no ventricular contraction occurs.

Question 20

What is the definition of hypertension?

Answer 20

Clinical BP ≥ 140/90 mmHg & ambulatory BP daytime average ≥ 135/85 mmHg

Question 21

What is the underlying cause of hypertension?

Answer 21

Primary: unknown
Secondary: resulting from another medical condition (e.g. kidney disease, adrenal disease)

Question 22

What investigations need to be performed to confirm diagnosis of hypertension?

Answer 22

Blood pressure measurement: readings ≥ 135/85 mmHg

Question 23

What is the treatment for hypertension?

Answer 23

Lifestyle changes followed by anti-hypertensive medication

Question 24

Why is hypertension problematic?

Answer 24

Hypertension itself isn’t the problem but rather, the sequelae/consequences of prolonged hypertension are problematic. Increases risk of stroke, myocardial infarction and kidney disease. These conditions increase risk of hypertension.

Question 25

What are acute coronary syndromes?

Answer 25

1. Angina: chest pain due to myocardial ischaemia caused by atherosclerosis
2. Non-ST-elevated myocardial infarction (NSTEMI): Myocardial tissue damage due to prolonged ischaemia caused by atherosclerosis and artery blockage
3. ST-elevated myocardial infarction (STEMI): Serious myocardial tissue damage due to prolonged ischaemia caused by severe atherosclerosis and complete artery blockage

Question 26

What are the underlying causes of acute coronary syndromes?

Answer 26

Atherosclerotic lesions of the coronary artery causing ischaemia (angina), artery blockage (NSTEMI) and then complete artery blockage (STEMI)

Question 27

What are the signs and symptoms of acute coronary syndromes?

Answer 27

1. Angina: chest pain on exertion (stable) or at rest (unstable)
2. NSTEMI: chest pain, sweating, nausea & vomiting
3. STEMI: radiating chest pain, sweating, nausea & vomiting

Question 28

What are ECG findings and blood test findings for acute coronary syndromes?

Answer 28

1. NSTEMI: ST-depression/no changes & high troponin levels

2. STEMI: ST-elevation with reciprocal ST-depression & high troponin levels

Question 29

What are treatment options for acute coronary syndromes?

Answer 29

1. Angina: vasodilators
2. NSTEMI: coronary stents, antiplatelets, vasodilators, anti-emetics, oxygen & pain-relief
3. STEMI: coronary stents, antiplatelets, vasodilators, anti-emetics, oxygen & pain-relief

Question 30

Describe pathophysiology of acute coronary syndromes

Answer 30

In angina and NSTEMI, there is a small occlusion of the coronary arteries by an atheroma or atherosclerotic lesion. Angina less likely to show ECG changes but NSTEMI shows a depressed ST interval depending on where ischaemia is - angina is the associated pain. STEMI is more serious as there is complete occlusion of lumen and happens when atheroma bursts so a platelet plus is formed. Here an ST elevation is seen.