A 67-year-old man is admitted with palpitations. During examination of his JVP he is noted to have regular cannon waves.
Which one of the following arrhythmias is most likely to be responsible for this finding?
Correct Answer A:
Atrio-ventricular nodal re-entry tachycardia and ventricular tachycardia with 1:1 ventricular-atrial conduction may produce regular cannon waves. Complete heart block causes irregular cannon waves.
JVP: cannon waves:
Caused by the right atrium contracting against a closed tricuspid valve. May be subdivided into regular or intermittent.
Regular cannon waves:
Irregular cannon waves:
A 75-year-old woman is brought to the Emergency Department by her family. She has been getting more short of breath over the last 6 weeks and says her energy levels are low. An ECG on arrival shows atrial fibrillation at a rate of 114 / min. Blood pressure is 128/80 mmHg and a chest x-ray is unremarkable.
What is the appropriate drug to control the heart rate?
Correct Answer E:
Atrial fibrillation: rate control - beta blockers preferable to digoxin.
This question reiterates an important point which frequently comes up in exams - digoxin is no longer first-line for rate control in atrial fibrillation. Her shortness-of-breath is likely to be rate related and does not necessarily mean that she is in heart failure. This is supported by a normal chest x-ray. Please see the NICE guidelines for further information.
Atrial fibrillation: rate control and maintenance of sinus rhythm:
The Royal College of Physicians and NICE published guidelines on the management of atrial fibrillation (AF) in 2006. The following is also based on the joint American Heart Association (AHA), American College of Cardiology (ACC) and European Society of Cardiology (ESC) 2012 guidelines.
Agents used to control rate in patients with atrial fibrillation:
Agents used to maintain sinus rhythm in patients with a history of atrial fibrillation:
The table below indicates some of the factors which may be considered when considering either a rate control or rhythm control strategy:
A 75-year-old woman is reviewed following a 'collapse' yesterday. Her husband found her unconscious on the bathroom floor and describes her 'quickly coming round'.
What is the most likely cause of collapse in this patient?
Correct Answer C:
Reflex syncope is the most common cause of syncope in all age groups although orthostatic and cardiac causes become progressively more common in older patients.
Syncope:
Syncope may be defined as a transient loss of consciousness due to global cerebral hypoperfusion with rapid onset, short duration and spontaneous complete recovery. Note how this definition excludes other causes of collapse such as epilepsy.
The European Society of Cardiology published guidelines in 2009 on the investigation and management of syncope.
They suggested the following classification:
Orthostatic syncope:
Cardiac syncope:
Reflex syncope is the most common cause in all age groups although orthostatic and cardiac causes become progressively more common in older patients.
Evaluation:
A 76-year-old woman is admitted to the resus department after collapsing whilst shopping. The paramedics report she is hypotensive and tachycardia. Initial observations include a heart rate of 160 bpm and a blood pressure of 98 / 60 mmHg. A 12 lead ECG shows a broad complex tachycardia.
Which one of the following features on the ECG would suggest a ventricular tachycardia rather than a supraventricular tachycardia with aberrant conduction?
Broad complex tachycardia:
Features suggesting VT rather than SVT with aberrant conduction:
A 30-year-old woman is admitted to the Emergency Department following the acute onset of palpitations. Blood pressure is 124/84 mmHg and her pulse is 150/min. An ECG shows a narrow complex tachycardia. Intravenous access is gained and 6mg of adenosine is given with no effect.
What is the most appropriate next step?
Correct Answer B:
A further dose of adenosine should be given if there is no response to the initial injection.
Supraventricular tachycardia:
Whilst strictly speaking the term supraventricular tachycardia (SVT) refers to any tachycardia that is not ventricular in origin the term is generally used in the context of paroxysmal SVT. Episodes are characterized by the sudden onset of a narrow complex tachycardia, typically an atrioventricular nodal re-entry tachycardia (AVNRT). Other causes include atrioventricular re-entry tachycardias (AVRT) and junctional tachycardias.
Acute management:
Prevention of episodes:
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