CBL - Atrial Fibrillation

Question 1

What are the possible specific cardiology causes of heart failure? [6]

Answer 1

1. Myocardial dysfunction
   
   • e.g. myocardial infarction, cardiomyopathy
2. Volume overload
   
   • e.g. renal failure, severe mitral regurgitation
3. Obstruction to outflow
   
   • e.g. aortic stenosis
4. Obligatory high output
   
   • e.g. severe anaemia
5. Compromised ventricular filling
   
   • e.g. restrictive cardiomyopathy
6. Altered rhythm
   
   • e.g. AF with fast ventricular rate (“tachycardiomyopathy”)

Question 2

What investigations should be done on a patient with suspected atrial fibrillation? [7]

Answer 2

1. 12-lead ECG
2. Full blood count → to exclude anaemia
3. Urea & electrolytes
4. Cardiac marker (troponin-l or troponin-T)
5. Thyroid function tests
   
   • hyperthyroidism is associated with AF
6. Chest X-rays
   
   • to confirm the presence of pulmonary oedema
7. Transthoracic echocardiography
   
   • for further assessment of cardiac function

Question 3

What are the drugs typically used for treatment of heart failure? [6]

Answer 3

1. Diuretics
2. ACE inhibitors
3. Angiotensin-receptor blockers
4. Angiotensin-receptor neprilysin inhibitors
5. Beta-blocker
6. Mineralocorticoid receptor antagonists

Question 4

Why are diuretics used for the treatment of heart failure? [1]

Answer 4

for treatment of the symptoms of fluid overload in heart failure

Question 5

Why are ACE inhibitors used for the treatment of heart failure? [2]

Answer 5

they antagonise the actions of the renin-angiotensin-aldosterone system and act as vasodilators

• therefore may reverse some of the major pathophysiological mechanisms in heart failure

Question 6

What are the potential side effects of ACE inhibitors and what drug is used to replace ACE inhibitors if the side effects prove to be too problematic? [4]

Answer 6

1. cough
2. hypotension
3. renal dysfunction
4. Angiotensin-receptor blockers can be used as a replacement if cough proves to be a major issue

Question 7

Why must angiotensin-receptor neprilysin inhibitors not be given with ACE inhibitors? [1]

Answer 7

due to the risk of angioedema

Question 8

What are the common types of cardiac arrhythmias? [5]

Answer 8

1. atrial fibrillation
2. atrial flutter
3. supra-ventricular tachycardia
4. ventricular tachycardia
5. ventricular fibrillation

Question 9

What is atrial fibrillation? [3]

Answer 9

1. defined as continuous rapid activation of the atria at 300-600 beats/min
2. results in no coordinated electrical activity
3. ventricular rhythm is irregular and the rate is determined by AV nodal refractoriness

Question 10

What is atrial flutter? [4]

Answer 10

1. a circular movement of electrical activity within the atrium
   
   • basically the rhythm is self-perpetuating
2. it is commonly regular with 2:1 AV conduction
   
   • e.g. atrial rate 300 bpm, ventricular rate 150 bpm

Question 11

Describe a supra-ventricular tachycardia [4]

Answer 11

1. occurs due to a re-entry circuit using an extra electrical pathway which can be present within the AV node or as an accessory pathway or bypass tract
2. the SVT is usually initiated by an atrial extra-systole which finds the accessory pathway refractory to accepting stimulation in the direction of atrium to ventricle.
3. the electrical activity then passes through the normal conduction systems, and then is able to conduct back from the ventricle to the atrium through the accessory pathway
4. a circus movement is then initiated

Question 12

Name and describe the 3 types of atrial fibrillation [8]

Answer 12

1. Paroxysmal atrial fibrillation
   
   • the AF terminates spontaneously and usually lasts less than 48 hours, but may recur
2. Persistent atrial fibrillation
   
   • these patients remain in atrial fibrillation but sinus rhythm can be restored
   • e.g. by cardioversion either electrically or with drugs
3. Permanent atrial fibrillation
   
   • chronic
   • it is accepted that sinus rhythm can not be restored or may be inappropriate

Question 13

What is the appropriate treatment in patients with permanent established atrial fibrillation whom require regulation of ventricular rate? [3]

Answer 13

Beta-blocker or calcium channel blocker (diltiazem or verapamil), in combination with digoxin if necessary

Question 14

What drug is used for immediate cardioversion or for patients with severe left ventricular dysfunction (with AF)? [1]

Answer 14

amiodarone

Question 15

What is the CHADS₂ score used for and what are the components of it (what does each letter stand for)? [6]

Answer 15

• the CHADS2 score has been used for the assessment of thromboembolic risk

1. Cardiac failure,
2. Hypertension,
3. Age >75y,
4. Diabetes,
5. Stroke — 1 point for each, except 2 points for stroke

Question 16

Anticoagulation is recommended if the CHAD₂ score is…? [1]

Answer 16

score ≥2

Question 17

If the CHAD₂ score is 1, the CHA₂DS₂-VASc can be used. What are the components of CHA₂DS₂-VASc and how many points to you get for each part? [4]

Answer 17

1. 1 point for Vascular disease,
2. 1 point for Age 65-74y
3. 2 points for Age 75+,
4. 1 point for females (Sex categorical)
5. Again anticoagulation is recommended for scores of 2 and above.

Question 18

Name the anticoagulant drugs that can be used [5]

Answer 18

1. Aspirin
2. Warfarin, with a target INR of 2.5 (range 2-3)
3. New oral anticoagulants (NOACs):
   
   • dabigatran (direct thrombin inhibitor),
   • rivaroxaban and apixaban (factor Xa inhibitors)