Study Flashcards
What are cardiac arrhythmias
Accelerated, slowed or irregular heart rates caused by abnormalities in the electrical impulses of the myocardium
What are supra ventricular arrhythmias
Arrhythmias which originate in the sinoatrial node, atrial myocardium or atrioventricular node
Regular QRS complex
What are ventricular arrhythmias
Ones which originate below the atrioventricular node
Wide QRS complex
What are supraventricular premature beats
Atrial contractions triggered by ectopic foci rather than the sinoatrial node
They arise within the atria (atrial premature beats) or through retrograde conduction in the atrioventricular node (juntional premature beats)
What causes supraventricular beats
Idiopathic Potential triggers: -smoking -alcohol -coffee Cardiovascular disease or electrolyte imbalances (eg hypokalaemia)
What are the atrial premature beats
Extrasystole that originates in the atrial myocardium and occurs prior to the expected QRS complex
What are the ECG findings of atrial premature beats
P wave abnormalities or absent P waves
Altered PR interval in the premature beats, compared to the normal beats
QRS complec may be normal, aberrant (widened) or absent
No full compensatory pause
What are the ECG findings of junctional premature beats
Retrograde P wave
Narrow QRS complex
No compensatory pause
What are juntional premature beats
Premature beat that occurs prior to the expected QRS complex and the originates between the atria and the ventricles
How do supraventricalar beats present in patients
Usually asymptomatic
Palpitations
How do supraventricalar beats get diagnosed
ECG: identify supraventricular premature beats
Echocardiography: to rule out structural heart disease and evaluate cardiac structure and function if SPBs are identified on ECG
Further work up if structual abnormalities are present
How are supraventricular premature beats treated
Not required in asymtomatic individuals without underlying structural heart defects
Underlying conditions (eg electrolyte imbalances) should be treated
Symptomatic patients:
- advise to reduce potential triggers like caffeine, alcohol, stress and smoking
- beta-blockers or catheter ablation in patients with persistent symptoms
What is atrial fibrillation
A common type of supraventricular tachyarrhythmia characterised by uncoordinated atrial activation that results in an irregular ventricular response.
Always evaluate for mitral valve involvement
What is the epidemiology of AF
Most common sustained arrhythmia
Incidence increases with age; lifetime risk of those >40 y/o is 1 in 4
>95% of individuals with AF are 60 years or older
~1% of US population
What are the major risk factors for AF
PARASITE
Pulmonary disease Anemia Rheumatic hear disease Atrial myxoma (a benign tumor found in the heart) Sepsis Ischaemia Thyroid disease Ethanol
What are the effects of AF
The atria contract rapidly but ineffectively and in an uncoordinated fashion leading to stasis of blood within the atria and so increasing risk of thromboembolism and stroke
Irregualr activation of the ventricles by conduction through the AV node leads to tachycardia
What are the clinical features of AF
- Most affected individuals are asymptomatic
- Less commonly, affected individuals develop symptoms of Arrhythmias such as palpitations, dizziness, syncope, fatigue or SOB
- May show signs of underlying disease causing AF
- Tachycardia with irregularly irregular pulse
- Apex-pulse deficit (difference between the rate of the apex heart beat and that of the peripheral pulse)
- Complications of long standing AF
What are the potential complications of longstanding AF
Acute left heart failure leading to pulmonary oedema Thromboembolic events - Stroke/ TIA - Renal infarct - Splenic infarct - Intestinal ischaemia - Acute limb ischaemia Life threatening ventricular tachycardia
How is AF diagnosed
ECG:
- Irregularly irregular rhythm
- Variable rate - tachycardia is common; atrial rate > ventricular rate
- No p waves or PR interval
- Typically narrow QRS complex (<0.12 secs)
FBC: to test for anaemia and infection U and Es to detect imbalances; kidney function (U and creat) Serum glucose to assess hyperglycaemia TFTs for hyperthyroidism LFTs for liver disease
Consider to evaluate complications and underlying aetiology:
- Troponin
- BNP
- Ddimer
- Serum toxicology
Echocardiogram
Chest Xray
What is atrial flutter
A supraventricular tachycardia that is usually caused by a macroreentrant rhythm within the atria
What are the ECG findings of atrial flutter
Rate: ~75-150 bpm
Atrial rate ≥ ventricular rate
Regular, narrow QRS complexes
Rhythm:
- regularly irregular is occurs with a variable AV block occurring in a fixed pattern
- irregularly irregular with a variable block occurring in a nonfixed pattern
Sawtooth appearance of P waves: identical flutter waves (F waves) that occur in sequence at a rate of ~300/min
How is AF treated
Unstable patient: immediate electical cardioversion
Stable patient: rate and rhythm control
Rate control:
Target HR:
- <110 bpm in asymptomatic or normal LV systolic function
- <80 bpm in symptomatic with a lenient rate
Consider especially in elderly
Contraindicated in AF due to preexcitation syndromes
Options:
First line:
-Beta blockers (not in COPD
-Nondihydropyridine calcium channel blockers (not in decompensated heart failure)
Second line:
-Digoxin (first line in decomp HF where BB contraindicated)
Third line:
-amiodarone (reserved for those where all other options have failed)
Surgical options:
AV noda; ablation and implantation of a permanent ventricular pacemaker
- indicated in recurrent AF or those who don’t tolerate pharmacological options
Rhythm control: Indicated in: - failure of rate control strategy - new onset AF - acute illness that precipitated AF - tachy induced cardiomyopathy, pregnancy, patient preference, younger patients Options are: -electrical cardio version -pharmacological cardioversion -interventional cardioversion Contraindications: -Long standing persistent AF -Reversible causes (eg digoxin toxicity or electrolyte imbalances) -High risk of thromboembolic events Initiate anticoagulation before cardioversion to reduce risk of stroke
What is the CHA2DS2-VASc score
A validated scoring system for asessing risk of stroke in nonvalvular AF 1- Congestive heart failure 1- Hypertension 2- Age ≥ 75 years 1- Diabetes 2- Prior Stroke, TIA or thromboembolism 1- Vascular disease 1- Age 65-74 1- Female sex
Risk of stroke: 0 points (male) or 0–1 point (female): low risk 1 point (male) or 2 points (female): intermediate risk ≥ 2 points (male) or ≥ 3 points (female): high risk
What is the HAS-BLED score
Scoring system used to assess the risk of bleeding in patients starting anticoagulation
High risk is not a reason to withhold anticoagulants, may just need greater monitoring
1- Hypertension
1 (each, max 2)- Abnormal renal or liver function
1- Stroke
1- Bleeding history or predisposition
1- Labile INR
1- Elderly (>65 years)
1 (each, max 2)- Drugs which predispose to bleeding, or alcohol use
Interpretation
0 points: low risk
1–2 points: moderate risk
≥ 3: high risk
What is atrial fibrillation with rapid ventricular response
AF with HR >100-110 bpm
