● AV nodal blocking drugs
(Class II, Class IV, Digoxin, Amiodarone)
● Spot Quiz – Which organophosphate was recently
used to assassinate the step-brother of a well known
● Up to 30% of patient with inferior STEMI will
develop second or third degree AV block.
● Associated with an increased in-hospital mortality.
● Inferior myocardial wall and the SA/AV nodes are
usually all supplied by the right coronary artery
● Cushing response.
● Raised BP, Bradycardia, Irregular breathing.
● Bradycardia is due to the baroreceptor response to
the sympathetic efforts to increase cerebral
perfusion – or mechanical distortion of the vagus
● Competitive muscarinic antagonist -
● Increases firing of the SA Node by blocking the
action of the vagus nerve.
● Onset of action ~ 1 minute
● Duration of action 30 – 60 minutes.
● The first drug of choice for symptomatic
● Dose in the Bradycardia ACLS algorithm is 0.5mg
IV push and may repeat up to a total dose of 3mg.
Spot Quiz – Who Am I
● Invasive Pest
● Solanaceae family
● Contains Tropane alkaloids
● Non-invasive pacing is used on a temporary basis
until the patient is stabilized and either an adequate
intrinsic rhythm has returned or a transvenous
pacemaker is inserted, whether temporary or
● Adrenaline (second line agent).
Non-selective A/B agonist.
Titrated to maintain a satisfactory HR.
● Dopamine – 2-10mcg/kg/min
● Isoprenaline – 2.5mcg/min
Patient with symptomatic bradycardia and a palpable pulse
who has not responded to pharmacological therapy (or no
IV access able to be established).
High-grade AV blockade (3rd
degree heart block or unstable
mobitz type II.
Cardiac arrest with ventricular standstill, but atrial activity
● Recent asystole.
Asystolic cardiac arrest
● For pacing readiness (i.e. standby mode) in the
setting of acute myocardial infarction (AMI) with
Symptomatic sinus bradycardia
Mobitz type II second-degree AV block
Third-degree AV block
New left, right or alternating bundle branch block or
Transcutaneous Pacing - Procedure
● O2 and IV Access.
● Sedation unless contraindicated.
● Placement of pads on clean, dry, shaven skin.
● Pacing mode with rate 60-80 bpm.
● Begin pacing at 5mA amp, increase amperage in
5mA increments until visible electrical capture-
(QRS-T complexes after each pacing spike).
● Check pulse for mechanical capture.
● Increase by a further 5mA after capture.
Classification of Bradycardia
● Absolute or Relative
● Functional or relative bradycardia occurs when a patient may have a heart rate
within normal sinus range, but the heart rate is insufficient for the patients
condition. An example would be a patient with an heart rate of 80 bpm when they
are experiencing septic shock.
● Narrow or Wide Complex
● Regular or irregular
● Sinus vs Sick Sinus vs AV nodal vs Ventricular
● 68 year old female.
● Presents with an episode of syncope on a
background of 1 week of vomiting and poor oral
● GCS 14 on arrival, HR 34, BP 80/53
● PMHx: HTN, CHF
● Medx: Spironolactone, Bisoprolol.
Case 1 (cont)
● K+ of 7.8
● Responded to IV calcium gluconate, IV insulin
dextrose and inhaled salbutamol.
● Always consider the diagnosis of hyperkalaemia in
patients presenting with bradycardia or complete
Case 1 (cont)
● Severe bradycardia (HR ~ 30 bpm)
● Symmetrically peaked T waves in V2-5
● Flattening, broadening and near-disappearance of P
waves (still barely visible in V1-3)
● Prolongation of the PR interval
● Broad QRS complexes (~120 ms)
● 48 year old presents with sharp pleuritic
chest pain after playing a game of squash
● PMHx: BPH, Meningioma.
● Fhx: CAD.
● No recent immobilization or surgical history.
O/E Haemodynamically stable WNL. 3rd
heart sound heard.
● Regular physical activity leads to physiological
adaptions in cardiac dimensions. Primarily LV wall
thickness and cavity size.
● Enhanced diastolic filling with increased stroke
volume and cardiac output.
● Subsequent bradycardia, repolarization
abnormalities and voltage criteria for chamber
● Accentuated antagonism.
● Electrocardiographic findings that are common,
training-related, normalize with exercise and that do
not require additional evaluation are:
● Sinus bradycardia
● 1° atrioventricular block or mobitz 1 are common.
● Incomplete right bundle branch block (BBB)
● Early repolarization.
● Isolated voltage criteria for left ventricular
Athlete's Heart (cont)
● With voltage criteria for LVH, pathological
hypertrophy should be suspected in any of the
● Left atrial enlargement,
● Left-axis deviation,
● Repolarization abnormalities,
● Pathological Q waves.
● T-wave inversion ≥2 mm in ≥2 adjacent leads.
● 74 year old lady with sudden onset 30 minute
episode of crushing central chest pain, radiating to
neck and associated with diaphoresis and
● Previous similar episodes for the last 6 months on
exertion however only mild in severity.
● PMHx: Diabetic, HTN, Hypercholesterolaemia.
● Shx: Smoker
● O/E – HR 42, BP 102/60, Sats 97% on RA.
Case 3 (cont)
● Regular, narrow complex bradycardia.
● Ventricular rate of 43 BPM.
● Complete AV block.
● Likely junctional escape rhythm.
● Significant ST elevation in leads II, III, and AVF,
with reciprocal ST depression in leads I and AVL,
all suggestive of an inferior STEMI.
Case 3 (cont)
● Inferior STEMI with RV infarction was diagnosed.
● IV fluids were given.
● Aspirin, Ticagrelor and Heparin were given
● Patient taken to cath lab:
● Coronary angiography revealed an acute thrombus
with 100% occlusion of the proximal Right
Coronary Artery (proximal to the right ventricular
marginal branch), successfully stented and reduced.
● Remember ABC'ss
● Assess and treat underlying causes
● Reassess regularly for changes in rhythm.
● Decision to treat largely based on
haemodynamic stability and risk of asystole.
● Clear algorithms provided by APLS/ACLS
available for treatment.
● ACLS/APLS Australia
● Australian Resuscitation Council
● Textbook of Cardiology.org
● Family Practice Notebook
● Dr Smith's ECG Blog
● Dr Venkatesan.com
● Department of Agriculture and Food.