Atrioventricular Blocks and Bradyarrhythmias Flashcards
What is an atrioventricular block?
It is a !delay or disruption! in the transmission of electrical impulses from the atria to the ventricles !due to anatomic or functional impairment of the conduction system!
What drugs may cause AV block/Bradyarrhythmias?
Beta blockers, CCB, Digoxin (BCD)
What are the infectious causes of AV block/bradyarrhythmias
Infectious: Lyme Disease, Viral myocarditis
List the causes of an AV block/bradyarrhythmias
physiological: Increased vagal tone (e.g. athletes)
Degenerative -> Fibrosis/sclerosis
Below same as HF
Ischemic: MI/CAD
Infiltrative: Sarcoidosis, amyloidosis, haemochromatosis
Genetic: Hypertrophic/dilated cardiomyopathy
Infectious: Lyme Disease, Viral myocarditis
Hyper/hypothyroidism
Drugs: Beta blockers, CCB, Digoxin (BCD)
Post-cardiac surgery
What are the symptoms of bradyarrhythmias?
Mostly asymptomatic
Palpitations/increased awareness/Skipped beat
Syncope/presyncope, dyspnoea, chest pain
Would you expect to find raised JVP in bradyarrhythmias?
You would see raised JVP and even Cannon A waves in 3rd degree heart block
You are performing a cardiovascular examination on a patient with suspected AV block. On general inspection you note a scar close on the upper left chest. For the following parts of the examination, state 1 finding consistent with AV block/Bradyarrhythmias:
Vitals:
Closer inspection:
Auscultation:
Vitals: Bradycardic pulse
Closer inspection: Raised JVP - Cannon A waves in Type III
Auscultation: Reduced overall HS especially in S1
What is the best predictor of prognosis and also for whether a patient may need a pacemaker?
Exercise stress test
What investigations would you like to perform for a patient presenting with Syncope and an ECG showing heart block
Same as every arrhythmia + Add Lyme disease serology
Bedside:
ECG/!Holter monitor: Depends on what type
Urine dipstick (sepsis)
Urinalysis (evidence of CKD to guide management between DOAC and Warfarin) + Toxicology (sympathetomimetics)
Bloods:
FBC - Anaemia, infection, low platelets if DIC, infection, sepsis)
CRP - raised in infl. + inf.
U&E - Hypomagnesia + hyper/hypokalaemia + medications
TFTs - hyperthyroidism
Troponin + CKMB (ischaemia as a cause or result of arrhythmia)
BNP - HF in severe arrhythmia
HbA1c and Lipid profile (RFs)
Imaging:
CXR - sx of HF (ABCDE)
ECHO - TTE - atrial/ventricular size (LA enlargement/LV hypertrophy), RV systolic pressure, valvular involvement, pericardial disease - TOE - LA (appendage) thrombus, Rule out vegetations in IE
Procedure: Exercise stress test - predictor of prognosis and also for whether a patient may need a pacemaker
Define a first degree heart block?
What are the most common causes?
How is it managed?
Prolonged PR>200 at rest due to slow/delayed AV conduction
Most commonly due to increased vagal tone (athletes) or medications (beta blockers, CCB, Digoxin)
Asymptomatic: no tx
Symptomatic: Candidate for pacemaker
How is the PR interval measured?
From the beginning of the Pw ave to the beginning of the QRS => Q
The patient is at rest. What is this rhythm strip showing? Explain why
Would the patient typically be symptomatic or asymptomatic?
This image is showing a first degree heart block as it shows the following:
1) PR >200 at rest
Asymptomatic
