Week Seven - Case Two Flashcards
how can atrial fibrillation only be confirmed
with an ECG demonstrating an irregularly irregular RR interval and absent or abnormal P waves
according to the British Heart Foundation statistics, how many patients have been diagnosed with AF in the UK
1.5 million
what is the biggest risk with AF
stroke
what is the definition of sustained absent P waves
more than 30 seconds
why does the irregular RR interval happen
af is disorganised electrical activity within the atria. this gives rise to absent or abnormal P waves. the AV node is usually unable to conduct at such rapid rates and consequently there is a degree of AV block.
during AF the ventricular conduction is random and hence it gives rise to the irregularity of the ventricular beats (irregular RR interval)
what is one of the major mechanism triggers of AF
pulmonary vein ectopy.
in AF patients, during embryonic development, sleeves of atrial tissue abnormally extend into the pulmonary veins. Ectopy arising from cardiomyocytes within one or more pulmonary veins can enter the left atrium and trigger AF, as well as sustain the arrhythmia
what sort of heart failure can AF result in
it can impair the heart function and result in HF with reduced left ventricular systolic function.
what is tachycardiomyopathy
The relationship between AF and heart failure is like the “chicken and the egg”. In some patients the AF drives the heart failure and is the sole cause (called “tachycardiomyopathy” or “tachycardia-induced cardiomyopathy”). It is usually reversible once the AF is controlled or sinus rhythm restored. In other patients the AF is merely a consequence of the heart failure. Often AF can exacerbate pre-existing heart failure causing decompensation.
what are the three important aspects of AF management
stroke prevention
symptom control
risk factors and comorbidities
what is the most common tool used to assess stroke risk
CHA2DS2VASc
if patients are at a high risk of stroke what should they be offered
anticoagulation
what is important to assess before starting anticoagulation and what is the score used for this
bleeding risk before starting anticoagulation
the score systems used are HASBLED or ORBIT score
what score on the HASBLED would require frequent monitoring
patients with a HASBLED score of 3 or more may be deemed high risk and require close monitoring.
what is recommended to patients with a high risk of stroke
oral anticoagulation
what CHA2DS2VASc score is deemed as high stroke risk
score of 2 or more in women, and score of 1 or more in men
what anticoagulants are used first line in patients with increased stroke risk
DOACs recommended first line
what is Apixiban only licensed for use in
patients with CKD who need oral anticoagulants
what do patents with heart failure and AF benefit from
an early rhythm control strategy with randomised control studies showing improved mortality following catheter ablation
what medications are used for rate control in AF patients
beta blockers
what medications are used to maintain sinus rhythm in AF
Amiodarone and flecainide
what surgery is used to maintain sinus rhythm
catheter ablation (pulmonary vein isolation ablation)
what else can be given
a permanent pacemaker plus AV node abalation
what is the most effective way of restoring sinus rhythm
cardioversion however it does not prevent the recurrence of AF
what is defined as an unsuccessful DC cardioversion
the inability to restore sinus rhythm even for one beat despite at least 4 weeks of Amiodarone therapy
what does non sustained mean
less than 30s duration
what does long standing persistent mean
more than one year
what does paroxysmal mean
between 30 seconds and up to one weekw
what does persistent mean
more than one week
what does sustained mean
more than 30 seconds
what are the treatment options for AF and rapid ventricular response
incude rate control versus rhythm control
what does of bisproolol is used to control rate
2.5mg
what is clopidogrel
an anti-platelet
what is clopidogrel used for in AF patients
prophylaxis to prevent stroke after a TIA
what is ramipril
an ACE inhibitor
what is ramipril used for
blood pressure control
what is bisoprolol
a beta blocker
what is bisioprolol used for
rate rhythm in AF
the next few questions are on different types of anti coagulants
what is the mechanism and dose (plus renal impairment dose) of warfarin
vitamin K antagonist
variable as per INR
RID- target 2.5, range 2-3
what is the mechanism and dose (plus renal impairment dose) of apixaban
factor Xa inhibitor
5mg twice daily
reduced 2.5mg twice daily
what is the mechanism and dose (plus renal impairment dose) of dabigatran
direct thrombin inhibitor
150mg twice daily
(reduced 110mg twice daily)
what is the mechanism and dose (plus impaired mechanism dose) of edoxaban
factor Xa inhibitor
60mg once daily
(reduced 30mg once daily)
what is the mechanism and dose (plus impaired mechanism dose) of rivaroxaban
factor Xa inhibitor
20mg once daily
(reduced 15mg once daily)
what should patients with mechanical heart valves or moderate to severe rheumatic mitral stenosis offered
warfarin rather than DOACs
what does a dilated left atrium indicate
is common in patients with hypertension and often indicates left atrial stretch due to high intracardiac pressures
a dilated LA may predispose patients to developing atrial fibrillation
what does this mean for DC cardioversion
the chances of successful DC cardioversion or maintaining a normal rhythm in patients with persistent AF and severely dilated LA is significantly reduced.
what other factors can help you decide between rate control versus rhythm control strategy in patients with AF
a rhythm control strategy is usually reserved for patients with symptoms refractory to medications or evidence of impaired left ventricular systolic function
when decided the long term strategy, it is important to assess a patient’s symptoms once they are rate controlled.
what are the main factors for rate control only
Long duration of persistent AF (i.e., >1 year)
Severely dilated left atrium
No or minimal symptoms
Unsuccessful DC cardioversion despite Amiodarone (defined as a no sinus beats following a DC shock after a minimum 4 weeks of Amiodarone.)
what are the main factors for rhythm control
Symptoms impacting on quality of life
Haemodynamic compromise due to AF
Heart failure or left ventricular systolic impairment
Intolerance to medications
Medications ineffective
Conduction disease or bradycardia
what is first line treatment for rate control in AF and what should be cautioned
beta blockers - bisprolol
This is first line. Start with a low dose and uptitrate according to HR and BP. Cautious use in patients with acute heart failure or elderly patients due to risk of hypotension.
what is second line for rate control in AF
calcium channel blockers - diltiazem or veramipril
who should calcium channel blockers be avoided in
patients with left ventricular systolic dysfunction as it has a negative inotropic effect
what can be added in poorly controlled rate control despite first or second line treatment
digoxin
what should you check when giving digoxin
check potassium as there is risk of toxicity in hypokalaemia and monitor renal function
levels can be taken to minimise risk of toxicity
what is useful in patients with a tachy-brady syndrome to allow introduction of medications to treat tachy episodes.
permanent pacemaker
it can be combined with an AV node ablation if medications are unsuccessful in rate control
what is first line for rhythm control in AF
flecainide
who should flecainide be avoided in
patients with coronary artery disease and structural heart disease
what else should you ensure when giving flecainide to reduce the risk of atrial flutter with 1:1 conduction
an AV nodal drug such as BB or CCB is given at the same time
what type of risk does flecainide have
pro-arrhythmia risk
who should sotalol be avoided in
patients with structural heart disease
what can sotalol cause in ECG
can cause QTc prolongation so should measure QTc interval prior to starting and after dose adjustments
what can Amiodarone be used in
patients with structural heart disease
what sort of monitoring is used in patients taking Amiodarone
Patients will need regular monitoring of LFT/TFT/renal function and lung function. Although an effective drug its side effect profile makes it undesirable to use in the longer term.
when is dronedarone given
Should only be used by Specialists. Less effective than Amiodarone but better side effect profile. Only use in paroxysmal AF and avoid in patients with heart failure or left ventricular impairment.
what is the only definitive treatment available for AF
catheter ablation
how is catheter ablation carried out
An invasive procedure usually day-case with local anaesthesia and sedation. A Cryoballoon is placed within the left atrium and the tissue is frozen to -50 degrees for 4 minutes. Each pulmonary vein is treated in sequence.2 Success rates around 70% in paroxysmal AF and 60% in persistent AF. Radiofrequency ablation can also be used.
what is not considered a long term treatment for AF but is effective at terminating AF but jot preventing recurrence
DC cardioversion
It is useful to help assess a patient’s symptoms (i.e., comparing symptoms in AF and normal sinus rhythm) and assess suitability for long term rhythm control. For example, a rhythm control strategy would not be recommended in patients with an unsuccessful DC cardioversion on Amiodarone.4
why do we avoid using bisoprolol and CCB agents together
high risk of AV. block
what is the most appropriate therapy for a 65 year old man with atrial fibrillation of longer than 48 hours before DC cardioversion
digoxin and warfarin
a patient with AF of longer than 48 hours duration is at risk of thromboembolism after cardioversion. Unless the patient is severely compromised, it is standard practice to prescribe anticoagulation to the patient with warfarin for a month before attempting elective cardioversion. During that time the ventricular rate is controlled by prescribing digoxin.
A 60-year-old woman presents to a&e with a one-day history of constant palpitations and chest discomfort, drowsiness and shortness of breath. On examination her airway is patent, resp rate of 28 breaths per minute, lung sounds note bibasal crackles, capillary refill time of 5 seconds, irregularly irregular pulse at a rate of 140 beats per minute, blood pressure 90/50, temp 36.5, blood sugar 6.2 and pitting oedema in both ankles. The ECG confirms AF. From the list below, what should be your initial management?
DC shock and heparin
In this case immediate DC shock is indicated because the patient is severely compromised. The administration of heparin decreases but does not abolish the risk of thromboembolism after cardioversion.
A 45-year-old female is seen by her GP after new onset AF. Her AF has been put down to an episode of pneumonia. She has no other PMH and is currently taking bisoprolol for rate control. She has no family history of strokes. She asks whether she needs to be on anticoagulation to prevent her from having a stroke. Her HASBLED score is 0. what should we prescribe her
Do not prescribe anything
Her CHADSVASC score is 1 due to her being female. With no other risk factors, NICE recommend not to issue any form of anticoagulation. A male with a score of 1 should be considered for anticoagulation. For AF, treatment would be lifelong, if started, in anyone with a score of 2 or above.
A 55-year-old man is admitted with an acute myocardial infarction and develops a short run of ventricular tachycardia (VT). He requires treatment for prophylaxis against recurrent VT and is given amiodarone. In this clinical scenario, what anti-arrhythmic classification is amiodarone?
A 55-year-old man is admitted with an acute myocardial infarction and develops a short run of ventricular tachycardia (VT). He requires treatment for prophylaxis against recurrent VT and is given amiodarone. In this clinical scenario, what anti-arrhythmic classification is amiodarone?
Class 3
how do class 3 drugs act
as potassium blockers, which prolong the plateau phase of the cardiac action potential and increase the absolute refractory period
as a consequence they also prolong the QT interval
what is the drug of choice used to treat VT
Amiodarone is the drug of choice to treat VT. When it is used chronically it has a number of adverse effects but these are not an issue in the acute scenario. These adverse effects include bradycardia, pulmonary fibrosis, hepatic fibrosis, corneal microdeposits (regress if drug is stopped), photosensitive rash and thyroid dysfunction.
A 55-year-old man, who is on Amitryptiline, presents with heart palpitations, nausea, shortness of breath and chest pain. He is given IV Magnesium and Ventricular Pacing for prophylaxis of a polymorphic ventricular tachycardia with a varying QRS axis and prolonged Q–T interval. Which arrhythmia was seen on ECG given this history?
Torsades de Pointes
This is torsades de points, which will often degenerate to ventricular fibrillation leading to cardiac arrest. Causes include drugs, electrolyte disturbance and congenital long Q–T syndrome. Conventional anti-arrhythmic will make this condition worse. The treatment of choice is intravenous magnesium sulphate and ventricular pacing at a high rate.
