atrial fibrillation and flutter Flashcards
supra ventricular tachycardia?
AV node re-entry (AVNRT) • Accessory pathway re-entry (AVRT) • Atrial tachycardia (AT)
result from…
“AV node dependent”
Generally narrow QRS (≤ 120 ms).
avnrt?
V1 - p wave right after QRS III - Inverted p wave right after QRS; pseudo s wave
re entrant arrythmia pathway?
- orthodromic ap to avn to hb to ap 2. antidromic ap to hb to avn to ap
ecg of orthodromic AVRT?
retrograde P waves some distance after QRS
node dependent re entrant tachycardias; management?
vagotonic manoeuvres: 1. carotid massage, 2. cough, 3. valsava. drugs: 1. adenosine, 2. verapamil, 3. beta blockers
adenosine?
Induces transient block in AV node
- stops SVT that is node-dependent
- unmasks atrial activity in AT (& sometimes terminates it)
• Contraindicated in asthmatics
management of node dependent SVT?
Reassure – Benign (unless underlying coronary disease or LV failure)
treatment: • Do nothing – PRN A&E visit for Adenosine • Drug therapy - ⅓ chance of being both effective and well-tolerated • Catheter ablation - > 95% cure rate - 1% - 2% complication rate - Now offered as 1st line therapy
wolff parkinson white syndrome?
short PR interval, delta wave, increase QRSd pre excited ECG=accessory pathway; pre excited ECG + symptoms = WPW syndrome
problem with antegrade ap conduction: VF/SCD from AF?
Risk of VF / SCD depends on antegrade RP of AP
A long antegrade RP does not preclude AVRT, but patient won’t be at risk of SCD during AF
accessory pathway?
Antegrade Conduction • Pre-excited ECG • + symptoms = WPW Retrograde Conduction (Concealed AP) • Normal ECG • Potential for AVRT • No risk of VF / SCD
add focal at pic
atrial fib and flutter?
Confirm with ECG • 1st priority: control heart rate & provide adequate antithrombotic Rx • Elucidate cause • For AF, long term, decide rate vs rhythm control • For AFL, almost always ablate
af why bother?
Commonest sustained arrhythmia (0.7% in 55-59 yr; 18% in those >85yr); prevalence to double next 50 yrs
Overall risk of thromboembolism : 5% / yr; majority are embolic strokes
1/3 of strokes in > 80‘s is due to AF
Stroke risk can be ameliorated
Only 25% of AF patients admitted with stroke are anticoagulated Hospitalisation cost : US$5 billion in 2008/9
af venus triggers?
Pulmonary Veins (top cause) • Superior vena cava • Coronary sinus • Ligament of Marshall
add peri atrial ganglia
af predisposing factors?
Age • Hypertension • Valvular heart disease • Cardiomyopathy • ASD • Congenital heart disease • IHD • Pericarditis
• Thyroid dysfunction • Lung disease e.g. COPD / PE / Pneumonia • DM • Alcoholism • Sleep Apnoea • Obesity • Chronic Renal disease
af types?
- first detected: only one diagnosed episode, 2. paroxysmal: recurrent episodes that self terminate in less than 7 days, 3. persistent: recurrent episodes that last moee than 7 days, 3. permanent: an ongoing lomg tterm episode
af clinical manifestation?
Silent (e.g. detected by practice nurse measuring BP) Palpitations Fatigue Effort intolerance / dyspnoea Dizziness TIA / Stroke Acutely ischaemic limb or bowel
Paroxysmal Recurrent AF - self terminate in < 7 days, & usu within 48 h Persistent Recurrent episodes, ea ≥ 7 days (Long-standing Persistent) Persistent for > 1 yr Permanent When SR is no longer deemed possible
Paroxysmal AF carries the same stroke risk as persistent or permanent AF
af management plan?
add poc
af basic evaluation?
Symptoms? Severity? Date of onset, duration, frequency Co-morbid disease (?DM ?prev CVA ?alcohol abuse ?thyroid) Previous Rx BP (? HT; ? haemodynamic instability) HR (? tachycardia) Heart murmurs / signs of heart failure (? valve or structural disease) Goitre / signs of lung disease 1st line Ix : ECG / TFT / biochemistry / Echo 2nd line Ix : Ambulatory rhythm recording, CXR, ETT, etc
af stroke risk
add chad pic
af: aspirin or warfarin?
20% RRR of stroke with Aspirin • 70% RRR of stroke with Warfarin (INR 2 -3)
• Balance between stroke risk vs bleeding risk
• Stroke risk: CHADS • Bleeding risk: HAS-BLED
bleeding risk?
has bled Hypertension (>160 mmHg systolic) 1 • Abnormal liver or renal function (Cr >200) (1 pt each) 1 or 2 • Stroke (esp lacunar stroke) 1 • Bleeding Hx or predisposition (e.g. anaemia) 1 • Labile INR 1 • Elderly (> 65 yr) 1 • Drugs (NSAID) / alcohol x‘s (>8u / wk) (1pt each) 1 or 2 (Max 9 points)
how to treat?
Maintaining sinus rhythm with AAD has no mortality benefit over simple rate-control of the arrhythmia.
• Decision to restore sinus rhythm, or just manage ventricular rate, is dictated by severity of AF symptoms & QoL.
stratergy for management of sr?
add pic
who should be selected?
add pic
drugs for rate control?
β-blockers (Atenolol, Bisoprolol, Metoprolol) avoid in acute decompensated heart failure; AFFIRM study
• Calcium antagonists (Diltiazem, Verapamil) avoid in acute decompensated heart failure
• Digoxin (often used in combination with above; caution in renal failure, elderly)
AF: target H
what to do in the middle of the night?
If AF < 48 hr, give LMWH, rate-limit or cardiovert (DC or drug).
If AF > 48 hr or unsure, give LMWH, then either rate-limit or cardiovert (after TOE). Then reassess.
If plan to cardiovert electively, therapeutic INR for at least 3 weeks pre- and then for 4 weeks post-cardioversion.
Regardless of AF duration, if presentation with acute heart failure / shock, give LWMH, urgent rate-control, urgent Echo, and often cardioversion (after TOE).
atrial flutter?
Less common than AF, but frequently co-exists with AF, and may be more troublesome
Shares same pre-disposing factors as AF, but particularly after atrial surgery
2 types: (1) CTI-dependent (A) Counterclockwise / Typical (B) Clockwise (2) Non-CTI dependent
Managed as per AF: i.e. thrombophylaxis + rate / rhythm-control (DC cardioversion, ablation, drugs).
Generally drug-resistant, but exquisitely sensitive to DC cardioversion.
Tends to recur, so ablation is 1st line Rx if uncompromised (esp if CCW CTI- dependent).
