Cardiovascular Diseases

Arrhythmias

Disturbance of heart rhythm and/or conduction.
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Arrhythmias
Sinus Rhythms Premature Beats Supraventricular Arrhythmias Ventricular Arrhythmias AV Junctional Blocks

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Sinus Rhythms
Sinus Bradycardia Sinus Tachycardia

Sinus Bradycardia

Deviation from NSR A sinus rate of less than 60/min

Causes of Sinus Bradycardia

• MI • Sinus node disease (sick sinus syndrome) • Hypothermia • Hypothyroidism • Cholestatic jaundice • Raised intracranial pressure • Drugs, e.g. β-blockers, digoxin, verap


Rhythm
30 bpm
Rate?
Regularity?
regular
normal
0.10 s
P waves?
PR interval?
0.12 s
QRS duration?
Interpretation?
Sinus Bradycardia

Sinus Tachycardia

Deviation from NSR -a sinus rate of more than 100/min

Causes of Sinus Tachycardia

Anxiety • Fever • Anaemia • Heart failure • Thyrotoxicosis • Phaeochromocytoma • Drugs, e.g. β-agonists (bronchodilators)


Rhythm
130 bpm
Rate?
Regularity?
regular
normal
0.08 s
P waves?
PR interval?
0.16 s
QRS duration?
Interpretation?
Sinus Tachycardia

Sinus arrhythmia

Phasic alteration of the heart rate during respiration (the sinus rate increases during inspiration and slows during expiration

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Premature Beats
Premature Atrial Contractions (PACs) Premature Ventricular Contractions (PVCs)

Premature Atrial Contractions

Deviation from NSR These ectopic beats originate in the atria (but not in the SA node), therefore the contour of the P wave, the PR interval, and the timing are different than a normally generated pulse from the SA node.

Rhythm

70 bpm
Rate?
Regularity?
occasionally irreg.
2/7 different contour
0.08 s
P waves?
PR interval?
0.14 s (except 2/7)
QRS duration?
Interpretation?
NSR with Premature Atrial Contractions

Premature Ventricular Contractions PVCs

Deviation from NSREctopic beats originate in the ventricles resulting in wide and bizarre QRS complexes.When there are more than 1 premature beats and look alike, they are called “uniform”. When they look different, they are called “multiform”

Rhythm

60 bpm
Rate?
Regularity?
occasionally irreg.
none for 7th QRS
0.08 s (7th wide)
P waves?
PR interval?
0.14 s
QRS duration?
Interpretation?
Sinus Rhythm with 1 PVC

Supraventricular Arrhythmias

Atrial Fibrillation Atrial Flutter Paroxysmal Supraventricular Tachycardia

Atrial Fibrillation

The most common sustained cardiac arrhythmia. AF can cause palpitation, breathlessness and fatigue. In patients with poor ventricular function or valve disease, it may precipitate or aggravate cardiac failure. AF is associated with significant morbidity ( Thromboembolic )and a twofold increase in mortality . AF can be classified as paroxysmal (intermittent episodes which self-terminate within 7 days), persistent (prolonged episodes that can be terminated by electrical or chemical cardioversion) or permanent.

Common causes of atrial fibrillation

Coronary artery disease (including acute MI)Valvular heart disease, especially rheumatic mitral valve diseaseHypertension Sinoatrial disease Hyperthyroidism Alcohol • CardiomyopathyCongenital heart disease Chest infection Pulmonary embolismPericardial disease Idiopathic (lone atrial fibrillation)

Atrial Fibrillation

Deviation from NSR No organized atrial depolarization, so no normal P waves (impulses are not originating from the sinus node). Atrial activity is chaotic (resulting in an irregularly irregular rate). Common, affects 2-4%, up to 5-10% if > 80 years old

Atrial Fibrillation

Etiology: Recent theories suggest that it is due to multiple re-entrant wavelets conducted between the R & L atria. Either way, impulses are formed in a totally unpredictable fashion. The AV node allows some of the impulses to pass through at variable intervals (so rhythm is irregularly irregular).

Rhythm

100 bpm
Rate?
Regularity?
irregularly irregular
none
0.06 s
P waves?
PR interval?
none
QRS duration?
Interpretation?
Atrial Fibrillation

Management

Full history, physical examination, 12-lead ECG, echocardiogram and thyroid function tests. Restoration of sinus rhythm (Rhythm control), Optimisation of the heart rate (Rate control) Prevention of recurrent AF, Reduction of the risk of thromboembolism, Treatment of underlying cardiac disease .

Rhythm control Pharmacologic cardioversion Flecainide ,Propafenon,AmiodaronElectrical cardioversion- Less than 48 hours direct cardioversion. - More than 48 hours +Anticoagulates for 4 weeks prior and 3 months after. Rate control Using Digoxin, β-blockers and calcium antagonists, such as verapamil or diltiazemCatheter ablation in refractory cases

Prevention of thromboembolism

Risk stratification is based on clinical factors using the CHA2DS2-VASc scoring system. Warfarin INR 2-3 Aspirin

Atrial Flutter

Etiology: a large (macro) re-entry circuit, usually within the right atrium encircling the tricuspid annulus with every 2nd, 3rd or 4th impulse generating a QRS (others are blocked in the AV node as the node repolarizes).

Atrial Flutter

Deviation from NSRNo P waves. Instead flutter waves (note “sawtooth” pattern) are formed at a rate of 250 - 350 bpm.Only some impulses conduct through the AV node (usually every other impulse)

Causes and Symptoms

Similar to atrial fibrillation Management Treat the cause Rate control -Digoxine B blocker,verapamil.Rhythm control –Amiodaron ,DCMaintanance B- Blocker or amiodaroneAnticoagulantCatheter ablation offers a 90% chance of complete cure and is the treatment of choice for patients with persistent symptoms

Atrial F

70 bpm
Rate?
Regularity?
regular
flutter waves
0.06 s
P waves?
PR interval?
none
QRS duration?
Interpretation?
Atrial Flutter

Paroxysmal Supraventricular Tachycardia (PSVTPSVT

Deviation from NSR The heart rate suddenly speeds up, often triggered by a PAC (not seen here) and the P waves are lost. Tends to occur in normal heart.

PSVT

Etiology: There are several types of PSVT but all originate above the ventricles (therefore the QRS is narrow). Most common: abnormal conduction in the AV node (reentrant circuit looping in the AV node). Rate 150-250

Paroxysmal Supraventricular Tachycardia (PSVT

74 148 bpm Rate?
Regularity?
Regular  regular Normal  none 0.08 s
P waves?
PR interval?
0.16 s  none QRS duration?
Interpretation?
Paroxysmal Supraventricular

Managment

Episode may be terminated by carotid sinus pressure or by the Valsalva manœuvre. Adenosine (3–12 mg rapidly IV in incremental doses until tachycardia stops) or verapamil (5 mg IV)Recurrent SVT, catheter ablation is the most effective therapy and will permanently prevent SVT in more than 90% of cases


Ventricular Arrhythmias
Ventricular Tachycardia Ventricular Fibrillation

Ventricular Tachycardia

Dangerous. Nearly in abnormal heart. 3 or more sucsussive PVC at rate of more than 120. Can occur in normal heart.

Ventricular Tachycardia

Deviation from NSR Impulse is originating in the ventricles (no P waves, wide QRS).

Ventricular Tachycardia

Etiology: There is a re-entrant pathway looping in a ventricle (most common cause). Ventricular tachycardia (VT) occurs most commonly in the settings of acute MI, chronic coronary artery disease, and cardiomyopathy.

Rhythm

160 bpm
Rate?
Regularity?
regular
none
wide (> 0.12 sec)
P waves?
PR interval?
none
QRS duration?
Interpretation?
Ventricular Tachycardia

Management

Treat cause. Hemodynamically unstable DC Stable IV amiodarone or lidocaine. With poor LV function indication for ICD

Ventricular Fibrillation

CARDIAC ARREST
F

Ventricular Fibrillation

Deviation from NSR Completely abnormal.

Ventricular Fibrillation

Etiology: The ventricular cells are excitable and depolarizing randomly. Rapid drop in cardiac output and death occurs if not quickly reversed

Rhythm

none
Rate?
Regularity?
irregularly irreg.
none
wide, if recognizable
P waves?
PR interval?
none
QRS duration?
Interpretation?
Ventricular Fibrillation

Asystole

FIRST DEGREE A-V HEART BLOCK
Rate: variable P wave: normal QRS: normal Conduction: impulse originates in the SA node but has prolonged conduction in the AV junction; P-R interval is > 0.20 seconds. Rhythm: regular This is the most common conduction disturbance. It occurs in both healthy and diseased hearts. First degree AV block can be due to: inferior MI, digitalis toxicity hyperkalemia increased vagal tone acute rheumatic fever myocarditis. Interventions include treating the underlying cause and observing for progression to a more advanced AV block.

FIRST DEGREE A-V HEART BLOCK

SECOND DEGREE A-V BLOCK MOBITZ TYPE I (WENCKEBACK)
Rate: variable P wave: normal morphology with constant P-P interval QRS: normal Conduction: the P-R interval is progressively longer until one P wave is blocked; the cycle begins again following the blocked P wave. Rhythm: irregular Second degree AV block type I occurs in the AV node above the Bundle of His. It is often transient and may be due to acute inferior MI or digitalis toxicity. Treatment is usually not indicated as this rhythm usually produces no symptoms.

SECOND DEGREE A-V BLOCK MOBITZ TYPE I (WENCKEBACK

SECOND DEGREE A-V BLOCK MOBITZ TYPE II
Rate: variable P wave: normal with constant P-P intervals QRS: usually widened because this is usually associated with a bundle branch block. Conduction: P-R interval may be normal or prolonged, but it is constant until one P wave is not conducted to the ventricles. Rhythm: usually regular when AV conduction ratios are constant This block usually occurs below the Bundle of His and may progress into a higher degree block. It can occur after an acute anterior MI due to damage in the bifurcation or the bundle branches. It is more serious than the type I block. Treatment is usually artificial pacing.

SECOND DEGREE A-V BLOCK MOBITZ TYPE II

THIRD DEGREE (COMPLETE) A-V BLOCK

Rate: atrial rate is usually normal; ventricular rate is usually less than 70/bpm. The atrial rate is always faster than the ventricular rate. P wave: normal with constant P-P intervals, but not "married" to the QRS complexes. QRS: may be normal or widened depending on where the escape pacemaker is located in the conduction system Conduction: atrial and ventricular activities are unrelated due to the complete blocking of the atrial impulses to the ventricles. Rhythm: irregular Complete block of the atrial impulses occurs at the A-V junction, common bundle or bilateral bundle branches. Another pacemaker distal to the block takes over in order to activate the ventricles or ventricular standstill will occur. May be caused by: digitalis toxicity acute infection MI and degeneration of the conductive tissue. Treatment modalities include: external pacing and atropine for acute, symptomatic episodes and permanent pacing for chronic complete heart block.

THIRD DEGREE (COMPLETE) A-V BLOCK

Bundle branch block and hemiblock
Left bundle branch block LBBB Right bundle branch block RBBB
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Questions