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Cardiac Flashcards

1
Q

Describe the stages of de and repolarisation in the contraction of the heart

A

0: rapid depolarisation due to influx of Na+
1: Rapid early repolarisation, efflux K+ with inactivation of fast Na+ channels
2: Repolarisation slowed by Ca2+ influx
3. Rapid repolarisation, K+ efflux
4. Diastole with steady state resting transmembrane voltage

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2
Q

What is AF?

A

Most common arrhythmia (1-2% population)
Atrial fibrillation
Irregular baseline, ventricle contraction irregularly irregular
Increases risk of hospitalisation, stroke, cardiomyopathy

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3
Q

Treatment of AF

A

Cardioversion:
Electrical w/DC current
Chemical: amiodarone/flecanide

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4
Q

When should flecanide be avoided in AF?

A

Don’t use flecanide with underlying ischaemic heart disease or structural abnormalities

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5
Q

Do you anticoagulate AF patients?

A

Yes
Use CHA2DS2 VASc score and HAS-BLED can quantify stroke risk
WARFARIN, NOAC (DABIGATRAN, RIVAROXABAN)

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6
Q

If cardioversion for AF does not work, what do you do?

A

Rate control: Beta-blockers, VERAPAMIL, DIGITALIS
Rhythm control: SOTALOL, FLECANIDE, AMIODARONE
Catheter ablation (if ectopic foci and paroxysmal AF)

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7
Q

8 causes of pathological bradycardia

A
  • Cardiac surgery
  • Chronic degeneration of AV or SA nodes
  • Cholestatic jaundice
  • Hypothermia
  • Hypothyroidism
  • Ischaemia/infarction of SA node
  • Raised ICP
  • Drugs: amiodarone, beta-blockers, diltiazem/verapamil, lithium salts, morphine, clonidine, anticholinesterase inhibitors (donepezil, rivastigmine)
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8
Q

Treatment of pathologic/symptomatic bradycardia

A

Stop ß-blockers/other causative drugs
Treat underlying cause (levothyroxine)
Acutely Atropine (reduces vagal inhibition) IV 500micrograms, repeat every 3-5mins

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9
Q

What is a sinus pause?
Causes?
Symptoms?

A 
Sa node fails to generate impulse
Caused by:
•	Acute myocarditis
•	Digoxin toxicity
•	Fibrosis of SA node (ageing)
•	SE of antiarrythmic drug
•	MI
•	Stroke
Breathlessness, lethargy, dizziness, collapse, falls
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10
Q

Treatment of sinus pause?

A

Permanent pacemaker

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11
Q

What is sick sinus syndrome?

A

Palpitations caused by sinus bradycardia, sinus pause, paroxysmal atrial/tachy arrhythmias
Treatment: pacemaker/ rate controlling drugs

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12
Q

8 causes of AV block

A
  • Cardiomyopathy
  • Conduction system fibrosis
  • Connective tissue disease
  • Hypothyroidism
  • IHD
  • Radiotherapy
  • Sarcoidosis
  • Drug induced (beta-blockers, diltiazem, digoxin)
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13
Q

When are pacemakers indicated?

A

Pacemakers are indicated in:
• RBBB/LBBB with intermittent 3rd degree AV block
• Carotid sinus hypersensitivity
• Pauses of >3secs during the day
• Sustained VT with pauses
• Symptomatic bradycardia
• Symptomatic sinus node dysfunction/2nd degree heart block

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14
Q

How do you differentiate between tachyarrhythmias?

A

Is it regular? No
⇒ irregularly irregular AF
⇒ unconscious patient VF

Is the QRS broad?
⇒ Yes means ventricular origin
⇒ No means supraventricular origin

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15
Q

What does atrial flutter look like?

A

P-wave rate>250/min
2:1 or 3:1 P:R ratio
Characteristic saw tooth baseline

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16
Q

Treatment of supraventricular tachycardia

A

Give adenosine to block AV node. If this terminates the tachycardia-> AVRT/AVNRT
If it is independent of AV node-> focal atrial tachycardia
AVRT: atrioventricular re-entry tachycardia
AVNRT: atrial node re-entrant tachycardia

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17
Q

How do you treat a patient with a tachyarrhythmia who is haemodynamically compromised?

A

Electrical cardioversion under anaesthesia and sedation

Then IV amiodarone/beta-blocker

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18
Q

How do you manage a haemodynamically stable pt with a tachyarrhythmia?

A

Continuous ECG monitoring
Vagontonic manoeuvres (carotid massage, valsalva)
IV adenosine
Rate control with IV lidocaine

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19
Q

Treatment of supraventricular tachycardia

A 
Rate control (ß-blocker, verapamil, digoxin)
Rhythm control (amiodarone, flecanide, sotalol, DC shock)
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20
Q

Prevention of supraventricular tachycardia

A

Amiodarone
Sotalol
Quinidine
Procainamide

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21
Q

Causes of AF

A
  • Atrial septal defect
  • Cardiomyopathies
  • Diabetes mellitus
  • COPD
  • CKD
  • HTN
  • Obesity
  • CCF
  • Thyroid dysfunction
  • Valvular heart disease
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22
Q

Define 1st degree heart block

A

Conduction across AV node is delayed
Prolonged PR interval
Doesn’t need treatment

23
Q

Define 2nd degree heart block

A

Mobitz 1: PR interval progressively lenthens until QRS in dropped
Mobitz 2: Fixed number of p waves conduct (eg 3P to every 1 QRS). Conduction block at bundle of His

24
Q

Where is the conduction block with Mobitz 2 2nd degree AV block?

A

Bundle of His

25
Define 3rd degree heart block
Complete dissociation between atria and ventricle contraction (P waves and QRS) Atrial signal fails to reach ventricles Can lead to sudden cardiac death
26
Describe sinus arrhythmia
HR INcreases on INspiration
27
What is left axis deviation? | 4 causes
``` (I +ve, AVF –ve) • Left bundle branch block (treat w/pacemaker) • Left ventricular hypertrophy • Inferior MI • Wolff-Parkinson White Syndrome ```
28
Name 5 causes of right axis deviation
* Lateral MI * Lung consolidation (COPD, PE) * Right ventricular hypertrophy * Hyperkalemia * WPW syndrome
29
How do p-waves change in atrial enlargement?
Spiked in right atrial enlargement, mountains in left atrial enlargement.
30
What can t wave morphology show?
* Flattening/inversion = ischaemia | * Tall, peaked = hyperkalaemia
31
Name 3 types of supraventricular tachycardia
* Sinus tachycardia * Atrial flutter * Atrial fibrillation
32
Describe ventricular tachycardia | Treatment?
Raised HR, absent p wave, wide QRS. | CPR if unconscious, electrical cardioversion under anaesthetic if awake. Beta-blockers/AMIODARONE.
33
Define ventricular fibrillation
Ventricles don’t contract defined way. Absent p wave, QRS and T. Irregular waves with varying morphology and amplitude.
34
Treatment of ventricular fibrillation
CPR (shockable)
35
What is PEA?
Pulseless electrical activity | Non shockable because the electrical system in the heart is actually working properly
36
How do you calculate oxygen content?
Hb x SaO2 x 0.13 (ml/L)
37
What is venous return influenced by?
* Cardiac output * Muscle pump * Venous valves * Thoracic pump
38
Why should heavily pregnant ladies by positioned in left lateral position?
To avoid obstructing IVC
39
What 7 things determine blood flow?
``` Blood viscosity- • Haematocrit • Temperature (hypothermic) • RBC membrane integrity Vessel wall- • Lumen (tone) • Driving pressure • Endothelial integrity • Length ```
40
What is dangerous about injecting steroids (eg for muscle gain)
Hyperlipidaemia Liver cancer Pancreatitis Poor perfusion
41
Why is a cardiac MRI done?
Only in stable patients Investigation for cardiac ischaemia/post infarction Congenital heart defect visualisation
42
Define ACS
Acute coronary syndrome | Lack of oxygen reaching heart tissue, causing myocardial ischaemia due to atheroma formation in coronary arteries
43
Pathophysiology of MI
* Endothelial injury (raised LDL, toxins from smoking, hypertension, hemodynamic stress) * Expression of adhesion molecules * Platelet adhesion and PDGF released * Insudation of lipids and LDL oxidized by macrophages * Adhesion and migration of monocytes into macrophages * Uptake of LDL’s lipid by macrophages-> foam cells * Smooth muscle proliferation & migration to intima * Cap forms over foam cells * Smooth muscle produces matrix and turns into myofibroblasts * Foam cells secrete cytokines * More inflammatory cells are recruited * Foam cells apoptose and secrete lipid * Inflammatory cells produce proteases and weaken cap * Rupture of cap = haemorrhage from plaque microvessels * Platelet thrombus and coagulation * Embolism or fibrosis or resolution
44
Signs and symptoms of MI
* Intense compressive chest pain-> L arm and jaw * Nausea and vomiting * Sweating and clammy * Dyspnoea (SOB) * Longer than 20 mins (ie not angina)
45
How is an MI diagnosed
* Increased troponin levels * Symptoms of ischaemia * ECG changes (ST elevation, T wave inversion, deep Qs) * Loss of myocardium on echo * 4th heart sound * Angiography showing constriction/blockage
46
Describe the treatment of an MI
* 1º angioplasty * Antiplatelet (ASPIRIN, CLOPIDOGREL) * Thrombolysis (rTPA) * Anticoagulant (HEPARIN, WARFARIN, NOAC) * Pain relief (opiate) * GTN * O2 * Antiemetic (METOCLOPRAMIDE) * Protect myocardium (ATENOLOL, LISINOPRIL ACEi) * Secondary prevention (statin, lifestyle, aspirin)
47
Define pericardial tamponade
Accumulation of fluid in the pericardial space, resulting in reduced ventricular filling and subsequent haemodynamic compromise Medical emergency-> pulmonary oedema, shock & death.
48
Name 9 causes of pericardial tamponade
Same as pericarditis causes • Malignancy • Acute MI/post transmural infarction (fibrinous exudate) • Infection (esp viral, HIV) • Ureamia (metabolic toxins causing inflammation, from kidney failure) • Radiation • Autoimmune (RA, SLE) • Trauma (penetrating injury) • Iatrogenic cardiac perforation (central line placement, pacemaker insertion, cardiac catheterization, sternal bone marrow biopsies, pericardiocentesis) • Aortic dissection
49
Signs and symptoms of pericardial tamponade
* Tachypnoea * Tachycardia * Cold & clammy extremities * Elevated jugular venous pressure (on inspiration/Kussmaul) * Pulsus paradoxus (exaggeration of inspiration lowering BP) * Chest pressure * Decreased urine output * Confusion * Dysphoria (impending death, restless) * Others based on underlying cause (eg weight loss if malignancy)
50
Differential diagnosis in pericardial tamponade
* Cardiogenic Shock * Pericarditis * Pneumothorax * Pulmonary Embolism
51
What would be seen on echo to diagnose pericardial tamponade
* An echo-free space posterior and anterior to the left ventricle and behind the left atrium * Early diastolic collapse of the right ventricular free wall * Late diastolic compression/collapse of the right atrium * Swinging of the heart in the pericardial sac * Left ventricular pseudohypertrophy * Inferior vena cava plethora with minimal or no collapse with inspiration * A greater than 40% relative inspiratory augmentation of blood flow across the tricuspid valve or greater than 25% relative decrease in inspiratory flow across the mitral valve
52
What would be seen on ECG to diagnose pericardial tamponade?
Sinus tachycardia, low-voltage QRS complexes which alternate, PR depression
53
What would be seen on CXR to diagnose pericardial tamponade?
Cardiomegaly Chest wall trauma Pericardial calcifications
54
Management of pericardial tamponade
* O2 * Fluids * Leg elevation * Emergency subxiphoid percutaneous drainage * Pericardiocentesis (with or without echocardiographic guidance) * Percutaneous balloon pericardiotomy

Acute Care (11 decks)

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