CV Disorders Flashcards
Define heart failure
- Heart unable to maintain adequate circulation for metabolic requirements of body
- Preserved ejection fraction (HFpEF): EF ≥ 50%, ↓ diastolic function
- Reduced ejection fraction (HFrEF): EF ≥ 40%, ↓ systolic function
What is the underlying cause of heart failure?
Secondary to cardiac damage (ischaemia, myopathy), hypertension, valve disease
What is a sign of heart failure?
Exertional dyspnoea
What tests are done to diagnose heart failure?
Blood test: elevated brain natriuretic peptide (BNP)
Chest X-ray: cardiomegaly
What are the treatment options for heart failure?
Drugs that reduce the exertional pressure on the heart
Describe the pathophysiology of heart failure
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.
What does an ECG trace for heart failure look like?
Enlarged QRS complex due to increased muscle mass in the heart and hence larger electrical current generation. However, not always found in heart failure.
How is atrial arrhythmia defined?
- Atrial fibrillation (AF): Disorganised electric activity and contraction
- Wolff-Parkinson-White (WPW): Syndrome causing tachycardia & abnormal cardiac electrical conductance
What is the underlying cause of atrial arrhythmia?
AF: Spontaneously active cells throughout the atria.
WPW: additional accessory conduction pathway (the bundle of Kent) between the atria and ventricles.
What is a sign of atrial arrhythmia?
Palpitations & chest pain
What are the ECG findings in a case of atrial arrhythmia?
AF: Absent p-waves & ‘irregularly irregular’ rhythm.
WPW: QRS pre-excitation & biphasic/ inverted T-wave of ECG
What are the treatment options for atrial arrhythmias?
AF: strategies to maintain sinus (e.g. cardioversion, anti-arrhythmics, catheter ablation)
WPW: benign, no treatment required
Describe pathophysiology of atrial fibrillation
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.
Describe pathophysiology of Wolff-Parkinson White syndrome
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.
What are the different types of conduction block?
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
What are the underlying causes of a conduction block?
Damage (fibrosis, calcification, necrosis) to the conduction system (AV node or His Purkinje system)
What are the ECG findings in a case of conduction block?
- First-degree block: increased P-R interval
- Second-degree block: increased P-R interval or ‘missing’ QRS complexes, depending on type of block
- Third-degree block: p-waves not followed by QRS complexes
What are treatment options for a conduction block?
Discontinuation of AV-blocking drugs (e.g. beta-blockers, calcium channel blockers) or pacemaker implantation in severe cases.
Describe the pathophysiology of the different heart blocks
- 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.
- 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.
- 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.
What is the definition of hypertension?
Clinical BP ≥ 140/90 mmHg & ambulatory BP daytime average ≥ 135/85 mmHg
What is the underlying cause of hypertension?
Primary: unknown
Secondary: resulting from another medical condition (e.g. kidney disease, adrenal disease)
What investigations need to be performed to confirm diagnosis of hypertension?
Blood pressure measurement: readings ≥ 135/85 mmHg
What is the treatment for hypertension?
Lifestyle changes followed by anti-hypertensive medication
Why is hypertension problematic?
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.
What are acute coronary syndromes?
- Angina: chest pain due to myocardial ischaemia caused by atherosclerosis
- Non-ST-elevated myocardial infarction (NSTEMI): Myocardial tissue damage due to prolonged ischaemia caused by atherosclerosis and artery blockage
- ST-elevated myocardial infarction (STEMI): Serious myocardial tissue damage due to prolonged ischaemia caused by severe atherosclerosis and complete artery blockage
What are the underlying causes of acute coronary syndromes?
Atherosclerotic lesions of the coronary artery causing ischaemia (angina), artery blockage (NSTEMI) and then complete artery blockage (STEMI)
What are the signs and symptoms of acute coronary syndromes?
- Angina: chest pain on exertion (stable) or at rest (unstable)
- NSTEMI: chest pain, sweating, nausea & vomiting
- STEMI: radiating chest pain, sweating, nausea & vomiting
What are ECG findings and blood test findings for acute coronary syndromes?
- NSTEMI: ST-depression/no changes & high troponin levels
2. STEMI: ST-elevation with reciprocal ST-depression & high troponin levels
What are treatment options for acute coronary syndromes?
- Angina: vasodilators
- NSTEMI: coronary stents, antiplatelets, vasodilators, anti-emetics, oxygen & pain-relief
- STEMI: coronary stents, antiplatelets, vasodilators, anti-emetics, oxygen & pain-relief
Describe pathophysiology of acute coronary syndromes
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.
