Cardiac Arrythmias

Report
Cardiac Arrhythmias: An Update
Dr N.M.Gandhi
Consultant Cardiologist
Spire Gatwick Park Hospital, Horley
East Surrey Hospital, Redhill
Royal Sussex County Hospital, Brighton
Objectives
• Identify common arrhythmias encountered by
the family physician
• Discuss initial Mg options
• AF and Ventricular arrhythmias case studies
• Which patients needs to be referred? ECG
examples
THE CONDUCTION SYSTEM
Atrial Depolarization
Ventricular Depolarization
CARDIAC ARRHYTHMIAS
Disturbances of either :
• Impulse generation
• Impulse propagation
A
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 ELECTROPHYSIOLOGIC PRINCIPLES

BRADYARRHYTHMIAS
• SINUS NODE DYSFUNCTION
• AV CONDUCTION DISTURBANCES
 TACHYARRHYTMIAS
•ATRIAL TACHYCARDIAS
•VENTRICULAR TACHYCARDIA
Bradyarrhythmias
• Impulse formation:
– Decreased automaticity: Sinus bradycardia
• Impulse conduction:
– Conduction blocks: 1º, 2º, 3º AV blocks
Tachyarrythmias
• Impulse formation
– Enhanced automaticity:
• Sinus node: sinus tachycardia
• Ectopic focus: Ectopic atrial tachycardia
– Triggered activity
• Early afterdepolarization: torsades de pointes
• Digitalis-induced SVT
• Impulse conduction
– Reentry: Paroxysmal SVT, atrial flutter and fibrilation,
ventricular tachycardia and fibrillation.
Normal Sinus Rhythm
www.uptodate.com
Implies normal sequence of conduction, originating in the sinus node and
proceeding to the ventricles via the AV node and His-Purkinje system.
EKG Characteristics:
Regular narrow-complex rhythm
Rate 60-100 bpm
Each QRS complex is proceeded by a P wave
P wave is upright in lead II & downgoing in lead aVR
PAC
• Benign, common cause of perceived
irregular rhythm
• Can cause sxs: “skipping” beats,
palpitations
• No treatment, reassurance
• With sxs, may advise to stop smoking,
decrease caffeine and ETOH
• Can use beta-blockers to reduce frequency
PVC
• Extremely common throughout the population, both with
•
and without heart disease
Usually asymptomatic, except rarely dizziness or fatigue
in patients that have frequent PVCs and significant LV
dysfunction
PVC
• Reassurance
• Optimize cardiac and pulmonary disease
management
• Beta-blocker
• Ablation in a small number of cases
Bradyarrhythmias
• Impulse formation:
– Decreased automaticity: Sinus bradycardia
• Impulse conduction:
– Conduction blocks: 1º, 2º, 3º AV blocks
Sinus Bradycardia
• HR< 60 bpm; every QRS narrow, preceded by p wave
• Can be normal in well-conditioned athletes
• HR can be 30 bpm in adults during sleep, with up to 2
sec pauses
Sinus arrhythmia
• Usually respiratory--Increase in heart rate during
•
•
•
•
inspiration
Exaggerated in children, young adults and
athletes—decreases with age
Usually asymptomatic, no treatment or referral
Can be non-respiratory, often in normal or
diseased heart, seen in digitalis toxicity
Referral may be necessary if not clearly
respiratory, history of heart disease
Sick Sinus Syndrome
•All result in bradycardia
•Sinus bradycardia with a sinus pause
•Often result of tachy-brady syndrome: where a burst of
atrial tachycardia (such as afib) is then followed by a
long, symptomatic sinus pause/arrest, with no
breakthrough junctional rhythm.
1st Degree AV Block
• PR interval >200ms
• If accompanied by wide QRS, refer to cardiology, high
risk of progression to 2nd and 3rd deg block
• Otherwise, benign if asymptomatic
2nd Degree AV Block Mobitz type I
(Wenckebach)
• Progressive PR longation, with eventual non•
conduction of a p wave
May be in 2:1 or 3:1
2nd degree block Type II (Mobitz 2)
• Normal PR intervals with sudden failure of a p wave to
•
•
•
conduct
Usually below AV node and accompanied by BBB or
fascicular block
Often causes pre/syncope; exercise worsens sxs
Generally need pacing, possibly urgently if symptomatic
3rd Degree AV Block
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•
•
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Complete AV disassociation, HR is a ventricular rate
Will often cause dizziness, syncope, angina, heart failure
Can degenerate to Vtach and Vfib
Will need pacing, urgent referral
Tachyarrythmias
• Impulse formation
– Enhanced automaticity:
• Sinus node: sinus tachycardia
• Ectopic focus: Ectopic atrial tachycardia
– Triggered activity
• Early afterdepolarization: torsades de pointes
• Digitalis-induced SVT
• Impulse conduction
– Reentry: Paroxysmal SVT, atrial flutter and fibrilation,
ventricular tachycardia and fibrillation.
SUPRAVENTRICULAR T.
• Sinus Tachycardia
• Atrial flutter
• Atrial fibrilation
• Paroxysmal Supraventricular
• Multifocal Atrial T.
• Preexcitation Syndrome (Wolff-Parkinson-white Sy.)
Sinus tachycardia
• HR > 100 bpm, regular
• Often difficult to distinguish p and t waves
Paroxysmal Supraventricular T.
• Sudden onset and termination
• Atrial rates of 140 to 250 /min
• Normal QRS complexes
• The mechanism is most often reentry.
Paroxysmal Supraventricular
Tachycardia
• Refers to supraventricular tachycardia other
•
than afib, aflutter and MAT
Usually due to reentry—AVNRT or AVRT
PSVT
• CSM or adenosine commonly terminate
the arrhythmia, esp, AVRT or AVNRT
• Can also use CCB or beta blockers to
terminate, if available
• Counsel to avoid triggers, caffeine, Etoh,
pseudoephedrine, stress
Multifocal Atrial T.
• Is due to enchanced automaticity within
the atria, resulting in abnormal discharges
from several ectopic foci
• Most often occurs in the setting of severe
pulmonary disease and hypoxemia.
• EKG: irregular rhythm with multiple (at
leats 3) P waves morphologies
Atrial flutter
• Is caracterized by rapid coarse “sawtooth” appearing
atrial activity, at rate of 250 to 350 x min.
– Many of these fast impulses reach the AV node during
its refractory period, so that the ventricular rate is
generally lower.
• Frequently it degenerates into atrial fibrilation
– The most expiditious therapy is electrical
cardioversion, which is undertaken directly for highly
symptomatic patients. (to revert chronic refractory
atrial flutter that has not responded to other
approaches)
Preexcitation Syndrome
• Wolff-Parkinson-White Syndrome
• EKG: Although different types of bypass
tracts have been identified, the bundle of
Kent, is the most common and can usually
conduct in both the anterograde and
retrograde directions.
Atrial Fibrillation
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Irregular rhythm
Absence of definite p waves
Narrow QRS
Can be accompanied by rapid ventricular response
Atrial fibrillation--management
• Rhythm vs Rate control—if onset is within last
•
•
24-48 hours, may be able to arrange
cardioversion—use heparin around procedure
Need TEE if valvular disease (high risk of
thrombus)
If unable to definitely conclude onset in last 2448 hours: need 4-6 weeks of anticoagulation
prior to cardioversion, and warfarin for 4-12
weeks after
Atrial Fibrillation: Clinical Problems
• Embolism and stroke (presumably due to LA clot)
• Acute hospitalization with onset of symptoms
• Anticoagulation, especially in older patients (> 75 yr.)
• Congestive heart failure
–
Loss of AV synchrony
–
Loss of atrial “kick”
–
Rate-related cardiomyopathy due to rapid ventricular
response
• Rate-related atrial myopathy and dilatation
• Chronic symptoms and reduced sense of well-being
AF: Medical Management
• Treatment of underlying cause
• Ventricular rate control
• Anticoagulation
• Antiarrhythmics with a view to restore
sinus rhythm
Control of Ventricular Rate in
Atrial Fibrillation
• Betablockers
• Calcium channel blockers
Verapamil, diltiazem
• Digoxin
• Amiodarone
Anticoagulation
Anticoagulation
• Assessment of bleeding risk should be part of the clinical
assessment of AF patients prior to starting anticoagulation
• Antithrombotic benefits and potential bleeding risks of
long-term coagulation should be explained and discussed
with the patient
• Aim for a target INR of between 2.0 and 3.0
NICE 2006
CHADS 2 scoring
CCF
Hypertension
Age > 75
Diabetes
Stroke/TIA
1 point
1 point
1point
1 point
2 points
• Any patients with AF with a score of =/>2
would benefit from being on Warfarin
Cardioversion
Cardioversion
• Cardioversion results in SR in at least
90% of cases
• SR is only maintained in 30-50% at one
year
• Class 1a, 1c and III agents increase
likelihood of maintained SR from 30-50%
to 50-70% at one year
Follow-up
• Follow-up after cardioversion should take place
at 1 month, and the frequency of subsequent
reviews should be tailored to the patient
• Reassess the need for anticoagulation at each
review
Catheter Ablation for AF
AF Ablation
• Success rates – approx 70% but may require repeat
procedure
– Often increase in symptoms for first 3-6 months after
procedure does not indicate failure
• Risks
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–
–
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damage to existing conduction mandating pacing
Cardiac perforation/tamponade
Bleeding
Stroke/thromboembolism
Death
Catheter Ablation: Indications
• Symptomatic patients
• Refractory to Antiarrhythmics
• Medical therapy contraindicated due to comorbidities or intolerance
NICE 2006
Which AF patients need
Specialist Referral?
• Patients with:
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WPW syndrome
Uncontrolled ventricular rate (> 200/min)
Tachy-brady syndrome
For rhythm control strategy
CCF
Intolerant to Drugs
Invasive options
VENTRICULAR ARRHYTHMIAS
• Ventricular tachycardia
• Torsades De Pointes
• Ventricular fibrillation
Ventricular tachycardia
• Is divided in 2 categories:
– If it persist for more than 30 seconds
“sustained VT”
– Less than 30 seconds: “nonsustained VT”
• Symptoms vary depending on the
duration.
– Major manifestations are hypotension and loss
of consciousness.
Non-sustained ventricular tachycardia
• Need to exclude heart disease with Echo and
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•
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stress testing
May need anti-arrhythmia treatment if sxs
In presence of heart disease, increased risk of
sudden death
Need referral for EPS and/or prolonged Holter
monitoring
ICD may be life saving
Torsades De Pointes
• Varying amplitudes of the QRS.
• It can be produced by afterdepolarizations
(triggered activity).
• Particularly in prolonged QT interval.
• Occur with some drugs (quinidine),
electrolite disturbances, and congenital
prolongation of the QT interval.
Specialist Referral
ECG Examples
Contact...
* E-mail: [email protected]
[email protected]
* Fax: 01737 231938
* Phone: Spire - 01293 785511
ESH - 01737 768511, ext.6333

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