General Cardiology Flashcards
1
Q
What is the mechanism of action of Statins?
A
Statins inhibit the action of HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol synthesis
2
Q
What are adverse effects of Statins?
A
- Myopathy
- Liver impairment
- Increased risk of Intracereberal haemorrhage
3
Q
What are the myopathies caused by Statins?
A
- Types
- Myalgia
- Myosistis
- Rhabdomyolysis
- Asymptomatic Raised Creatine Kinase
- Myopathy is more common in lipophilic statins (simvastatin, atorvastatin) than relatively hydrophilic statins (rosuvastatin, pravastatin, fluvastatin)
4
Q
How is liver impairment managed in statins?
A
- Check LFTs at baseline, 3 months and 12 months.
- Treatment should be discontinued if serum transaminase concentrations rise to and persist at 3 times the upper limit of the reference range
5
Q
Who should receive statins?
A
- All people with established cardiovascular disease (stroke, TIA, ischaemic heart disease, peripheral arterial disease)
- Following the 2014 update, NICE recommend anyone with a 10-year cardiovascular risk >= 10%
- Patients with type 2 diabetes mellitus should now be assessed using QRISK2 like other patients are, to determine whether they should be started on statins
- Patients with type 1 diabetes mellitus who were diagnosed more than 10 years ago OR are aged over 40 OR have established nephropathy
6
Q
What is the statin used as Primary Prevention?
A
Atorvastatin 20mg OD
7
Q
When should statins be taken?
A
- Statins should be taken at night as this is when the majority of cholesterol synthesis takes place.
- This is especially true for simvastatin which has a shorter half-life than other statins
8
Q
How are statins used as Secondary Prevention?
A
Atorvastatin 80mg OD
9
Q
What are nitrates?
A
- Nitrates are a group of drugs which have vasodilating effects
- Work on Veins
10
Q
What is the mechanism of action of Nitrates?
A
- Causes release of nitric oxide in smooth muscle, increasing cGMP which leads to a fall in intracellular calcium levels in angina which both work to dilate the coronary arteries
11
Q
What are side effects of Nitrates?
A
- Hypotension
- Tachycardia
- Headaches
- Flushing
12
Q
How should Nitrate tolerance be managed?
A
Patient develop tolerances and experience reduced efficacy
- Patients who develop tolerance should take the second dose of isosorbide mononitrate after 8 hours, rather than after 12 hours.
- Allows blood-nitrate levels to fall for 4 hours and maintains effectiveness
- Effect is not seen in patients who take modified release isosorbide mononitrate
13
Q
What is adenosine used for?
A
Used to terminate supraventricular tachycardias
14
Q
What can enhance and block effects of adenosine?
A
- Adenosine are enhanced by Dipyridamole (antiplatelet agent)
- Blocked by Theophyllines
15
Q
When should adenosine be avoided?
A
Avoided in asthmatics due to possible bronchospasm.
16
Q
What is the mechanism of action of Adenosine?
A
- Causes transient heart block in the AV node
- Agonist of the A1 receptor in the atrioventricular node, which inhibits adenylyl cyclase thus reducing cAMP and causing hyperpolarization by increasing outward potassium flux
17
Q
What is the half life of adenosine?
A
8-10 seconds
- Ideally be infused via a large-calibre cannula due to it’s short half-life,
18
Q
What are some side effects of Adenosine?
A
- Chest pain
- Bronchospasm
- Transient flushing can enhance conduction down accessory pathways, resulting in increased ventricular rate (e.g. WPW syndrome)
19
Q
What is a Syncope?
A
- Defined as a transient loss of consciousness due to global cerebral hypoperfusion with rapid onset, short duration and spontaneous complete recovery.
20
Q
What are the types of Syncope?
A
- Reflex syncope (neurally mediated)
- Orthostatic syncope
- Cardiac syncope
21
Q
What causes Reflex Syncope?
A
- Vasovagal: triggered by emotion, pain or stress. Often referred to as ‘fainting’
- Situational: cough, micturition, gastrointestinal
-
Carotid sinus syncope
- Most common cause
22
Q
What causes Orthostatic Syncope?
A
- Primary Autonomic Failure: Parkinson’s disease, Lewy body dementia
- Secondary Autonomic Failure: e.g. Diabetic neuropathy, amyloidosis, uraemia
- Drug-induced: diuretics, alcohol, vasodilators
- Volume Depletion: haemorrhage, diarrhoea
23
Q
What causes Cardiac Syncope?
A
-
Arrhythmias:
- Bradycardias (sinus node dysfunction, AV conduction disorders)
- Tachycardias (supraventricular, ventricular)
-
Structural:
- Valvular
- Myocardial infarction
- Hypertrophic obstructive cardiomyopathy
-
Others:
- Pulmonary Embolism
24
Q
How do you assess syncope?
A
- Cardiovascular examination
-
Postural blood pressure readings
- Symptomatic fall in systolic BP > 20 mmHg or diastolic BP > 10 mmHg or decrease in systolic BP < 90 mmHg is considered diagnostic
- ECG
- Carotid sinus massage
-
Tilt table test
- 24 hour ECG
25
What is Pulsus Paradoxus?
Greater than the normal (10 mmHg) fall in systolic blood pressure during inspiration
26
What causes Pulsus Paradoxus?
* Severe asthma
* Cardiac tamponade
27
What causes a Slow-rising pulse?
**Aortic Stenosis**
28
What causes a collapsing pulse?
* **Aortic Regurgitation**
* **Patent ductus arteriosus**
* **Hyperkinetic States** (anaemia, thyrotoxic, fever, exercise/pregnancy)
29
What causes Pulsus Alterans?
* Regular alternation of the force of the arterial pulse
* Severe LVF
30
What causes Bisferiens Pulse?
* 'double pulse'
* Two systolic peaks
* Mixed Aortic Valve Disease
31
What are pulses for HOCM?
* Jerky Pulse
* Bisferiens pulse
32
What causes Ejection systolic mumurs?
* Aortic Stenosis
* Pulmonary Stenosis
* Hypertrophic obstructive cardiomyopathy atrial septal defect, tetralogy of Fallot
33
What causes late systolic?
* Mitral valve prolapse
* Coarctation of aorta
34
What causes early diastolic murmurs?
* **Aortic Regurgitation**
* high-pitched and 'blowing' in character
* **Graham-Steel murmur**
* pulmonary regurgitation, again high-pitched and 'blowing' in character
35
What causes mid-late diastolic murmurs?
* **Mitral stenosis**
* 'rumbling' in character
* **Austin-Flint murmur**
* severe aortic regurgitation, again is 'rumbling' in character
36
What causes continuous machine-like murmur?
**Patent ductus arteriosus**
37
What gives an S1 heart sound?
* **Closure of mitral and tricuspid valves**
* Soft in Long PR or Mitral Regurgitation
* Loud in mitral stenosis
38
What gives an S2 heart sound?
* Closure of **Aortic** and **Pulmonary** valves
* Soft in aortic stenosis
* Splitting during inspiration is normal
39
What gives an S3 heart sound?
* Caused by diastolic filling of the ventricle
* Considered normal if \< 30 years old (may persist in women up to 50 years old)
* Heard in left ventricular failure (e.g. dilated cardiomyopathy), constrictive pericarditis (called a pericardial knock) and mitral regurgitation
40
What gives an S4 heart sound?
* May be heard in Aortic stenosis, HOCM, hypertension
* Caused by atrial contraction against a stiff ventricle in HOCM a double apical impulse may be felt as a result of a palpable S4
41
What are some abnormal waves on ECG?
* Q waves are associated with a previous myocardial infarction
* Delta waves are associated with Wolff-Parkinson-White Syndrome
* Saddle ST elevation is associated with pericarditis
42
What are normal variants on the ECG?
* Sinus arrhythmia
* Right axis deviation (tall and thin individuals)
* Left axis deviation (short, obese individuals)
* Partial right bundle branch block
43
What are additional normal variants seems in athletes?
* Sinus bradycardia
* 1st degree atrioventricular block
* Wenckebach phenomenon (2nd degree atrioventricular block Mobitz type 1)
* Junctional escape rhythm
44
What are risk factors for myopathy in Statins?
**Risks factors for myopathy include:**
* Advanced age
* Female sex
* Low body mass index
* Presence of multisystem disease such as diabetes mellitus.
45
What are the effects of Nitrates on the heart?
* Causes **Venous Dilation**
* **Reduces Venous return** which in turn
* **Reduces left ventricular work so** reduced preload
* Reducing myocardial oxygen demand
