Arrhythmias Flashcards
Causes of bradyarrhythmias
Acute and chronic IHD CAD Valvular disease degenerative primary electrical dsiease sick sinus syndrome
Hypothyroidism
Elextrolyte imbalance (Hyperkalmeia)
Atunomic/neruologi causes
Autoimmunity
Drugs - BB and digoxin
Drug abuse
Situational - e.g bed rest
Treatment of bradyarrhythmias
In hemodynamically stable patietns:Atropine if condition of patient worsens
Unstable:
- Give O2 in case of hypoxia
- Administration of atropine also isoprenaline is necessary
- External pacing
Pacemaker indications:
- If no response to treatment
- 2nd degree AV block or worse
Types of supra ventricular arrhythmias
MAT
- Irregular, 100-200 BMP
- Random firing form several foci
- Very common in people with severe lung disease
- Need 3 P-waves w/different morphology
AVNRT - AV nodal reentry tachycardia
- Reentry inside the AV node.
- The retrograde P-wave is hidden in the QRS (uncommon type)
- Pseudo V1 and pseudo S in inferior leads (common type)
- 200 BMP
- Often triggered by premature atrial conduction
- Women > men
- severe palpitations and pounding in the neck
- Terminated by IV adenosine or vagal manoeuvres
- It can be controlled long term with β-blocker, vermeil
- RFA
AVRT - AV reentry tachycardia
- Retrograde conduction through the accessory pathway
- bigger reentry circuit
- Retrograde P-wave in the ST-T
- Narrow QRS = Orthodromic ( down the AV -node)
- Wide QRS = antidromic (down the accessory pathway)
Sinus tachycardia treatment and causes
- Exercise, pregnancy or emotion
- Anemia, cocaine, hyperthyroidism, pain, hypoxia, fever, infection, sepsis, shock, hypovolemia, cardiac tampnade, AHF, Pheochomocytoma
β-blocerks
Sinus nodal reentrant tachycardia treatment
β-blocker or CCB
Can also use ablation
P-wave on ECG is identical to sinus tachycardia
Atrial tachycardia treatment
Only for symptomatic patients:
- β blokcers and CCB
- Propafenone (Class 1C) or amidarone and stall (class III)
- May be terminated by IV adenosine or by RFA
Atrial flutter
P-wave rate > 240 BMP
Caused by reentrant over large areas if the right or left atrium.
Synchornized DC restores sinus rhythm
Drug therapy is not very effective, but amidarone can be used.
Ablation and pacemaker is the palliative solution.
AVRT types
WPW
- Bundle of kent
- conducts impulses faster
- Orthodromic - down the AV then back the accessory pathway. P wave that follows a narrow QRS
- Antidromic - down the accessory then back up AV. QRS wider than usual, often with delta wave. Very dangerous with AF as all impulses can be conudcted to the ventricles VT -> VF!!
Lown.ganone-levine syndrome
- James bundle
Treatment: Ablation, propafenone ( slow conduction in the accessor pathway and AV-node)
Junctional tachycardia
usually < 140 BMP
β blockers and propafenone are effective drugs
Treatment for SVTs
To achieve AV block use:
- Physical maneuvers
- Valsava - simules baroreceptors in arch of aorta
- Carotid massage - Drug treatment
- Adenosine - AV-nodal blocking agent, short acting, can be replaced with verapamil. - Electrical cardioversion
- DC shock (synchonized cardioversion)
Atrial fibrillation
- Irregulary irregular 300-600 BMP
- multiple reentrant circuits within try, often foci in pulmonary vein.
- main risk is embolic stroke, use WARFARIN
Symptoms on AF
- Asymptomatic chest pain palpitations ↓ CO dyspnea or faintness irregular pulse
Causes of AF
HT LVF CAD mitral or tricuspid valve disease HCM COPD
Alcohol binge hyperthyroidism Acute MI Acute pericardiits myocarditis PE Cardiac surgery
Rare causeS: - congenital heart disease Vagal overactivity pericardial effusion cardiac metastases
AF investigations
ECG - irregular ventricular rate, escape beats
CXR- cardiomegaly, pulmonary edema, mitral stenosis
Lab: hypokalemia, renal impairment; check Ca and Mg, thyroid function, liver function, cardiac enzymes, drug levels (digoxin)
ABG . hypoxic, shock or acidosis
Echo; LV function, valve lesions, pericardial effusion, exclude thrombus before conversion
Treatment of AF
Acute: - DC Drugs: - to control ventricular rate:1st line: β-blockers, CCB. 2nd line: digoxin - rhythm control: stall, propafenone - Heparin
Chronic
- Medical: bb, CCB, digoxin, amidarone
- Pacemaker - atrial pacing modes
- Atrial defibrillators
- Catheter and surgical ablation
Paroxymal AF
reccurent AF < 48h, convert spont to normal rhythm
Pill in pocket or BB, if this fails and no LV dysfunction: stall or amiodarone
electrical Cardioversion
Synchonized eletrical cardioversion
- Place on right of the sternum and one left to the left nipple.
- Shock is delivered in synchronisation with the R-wave, to prevent delivery of the shock in the vulnerable period (which could induce V.fib)
- Used for AF, A-flutter, sustained VT when there is pulse, junctional tachycardias
CI: digoxin toxicity, electrolyte disturbances, fever and ongoing met disturbances
Check thyroid function
Complications: Bradycardia, v-fib, thromboembolism, transient hypotension, skin burns, aspiration pneumonia
Pharmacological cardioversion
Adenosine may chemically cardiovert the heart.
Antiarrhythmic drugs: I: Na-chl blockers - lidocaine II: BBs III: Block outward K-chl - amiodarone IV: CCBs which inhibit AP in AV ans SA node
Ventricular arrhythmias
Lack response to IV adenosine (takes SVTs back to sinus) Causes: - IDH/HF - electrolyte dist - Post MI - hypotension/shock -Hypoxemia - Stimulants
- PVCs
- Accelerated idventricular rhythm
- Polymorphic VT -> torsades de pointes
- Ventricular tachycardia
- Ventricular fibrillation
Non pharmacological treatments of arrhythmias
Ablation
- Radiofrequency RF
- Cooled RF
- Cryoablation
- Indications: AVNRT, AVRT (WPW), A-flut, AT, PVC(monomorphic), AF.
- Complications: Death, stroke, cardiac tampnade, AV-node block, MI, pneumothorax
ICD
Pacemaker
CRT - cardiac resynchronisation therapy
Electrical cardioversion
Pacemaker - unternational code
International code:
1st letter: paced
2nd letter: sensed
3rd letter: I= inhibits, T=triggers, D=dual, 0=nothing
4th letter: added features of the device: R=rate responsiveness, M=multiprogrammable, C=communication, 0=neither
5th letter: antitachycardia functions: P=antitacycardia, S=shock (CV,DF), D=dual, 0=neither
Indications for pacemaker
Definite: 3rd degree AV block 2nd degree AV block - symtpmatic Bifascular or trifasciular after STEMI w/high degree AV block Symp sinus node dysf Symp chronotropic incomp Carotid sinus hypersens Sustained VT
Relative indications:
- High risk patients with long QT
- symptomatic HCM with outflow obstruction
- asymp 3rd degree AV block
CRT
Cardiac resynchronisation therapy treat HF (NYHA III-IV) In patients with ventricular conduction delay, coordination of wall motion in the left ventricle can improve by pacing LV and septum simultaneously -> improves CO and symptoms Ventricular filling may be optimised by AV delay
ICD
Used when there is risk for VT,V-fib and sudden death.
Have a lead in RV for pacing/sensing and defibrillator. May be a second lead in SVC
Use BB to prevent inappropriate shocking (e.g shock during sinus tachycardia)
Indications:
- survivors of CA due to VF or VT
- LEVF < 35% due to prior MI NYHA class II or III
- DCM LVEF < 35% and NYHA II or III
- HCM
- Long QT
- Brugada
