Cardiovascular Diseases pdf - د. جاسم محمد

fourth stage

Medicine

Lec-3

Dr.Jasim

2/11/2015

Arrhythmias

Arrhythmias is Disturbance of heart rhythm and/or conduction.



Sinus Rhythms



Premature Beats



Supraventricular Arrhythmias



Ventricular Arrhythmias



AV Junctional Blocks

1. Sinus Rhythms



Sinus Bradycardia



Sinus Tachycardia

 Sinus Bradycardia

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

Causes of Sinus Bradycardia



Sinus node disease (sick sinus syndrome)



Hypothermia



Hypothyroidism



Cholestatic jaundice



Raised intracranial pressure



Drugs, e.g. β-blockers, digoxin, verap

Rhythm



Rate ? 30 bpm



Regularity? regular



P waves? normal



PR interval? 0.12 s



QRS duration? 0.10 s



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



Rate? 130 bpm



Regularity? regular



P waves? normal



PR interval? 0.16 s



QRS duration? 0.08 s



Interpretation? Sinus Tachycardia

Sinus arrhythmia

• Phasic alteration of the heart rate during respiration (the sinus rate increases during

inspiration and slows during expiration

2. 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



Rate? 70 bpm



Regularity? occasionally irreg



P waves? 2/7 different contour



PR interval? 0.14 s (except 2/7)



QRS duration? 0.08 s



Interpretation? NSR with Premature Atrial Contractions

 Premature Ventricular Contractions PVCs

• Deviation from NSR

– Ectopic 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



Rate? 60 bpm



Regularity? occasionally irreg



P waves? none for 7th QRS



PR interval? 0.14 s



QRS duration? 0.08 s (7th wide)



Interpretation? Sinus Rhythm with 1 PVC

3. 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 disease



Hypertension



Sinoatrial disease



Hyperthyroidism



Alcohol • Cardiomyopathy



Congenital heart disease



Chest infection



Pulmonary embolism



Pericardial disease



Idiopathic (lone 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

• 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



Rate? 100 bpm



Regularity? irregularly irregular



P waves? none



PR interval? none



QRS duration? 0.06 s



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,Amiodaron



Electrical 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
diltiazem



Catheter ablation in refractory case



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).



Deviation from NSR



No 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 ,DC



Maintanance B- Blocker or amiodarone



Anticoagulant



Catheter ablation offers a 90% chance of complete cure and is the treatment of
choice for patients with persistent symptoms

hyth



Rate? 70 bpm



Regularity? regular



P waves? flutter waves



PR interval? none



QRS duration? 0.06 s



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.



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

Rhythm



Rate? 74 148 bpm



Regularity? Regular  regular



P waves? Normal  none



PR interval? 0.16 s  none



QRS duration? 0.08 s



Interpretation? Paroxysmal Supraventricular

Management



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

4. 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.



Deviation from NSR



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



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



Rate? 160 bpm



Regularity? regular



P waves? none



PR interval? none



QRS duration? wide (> 0.12 sec)



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



Deviation from NSR : Completely abnormal



Etiology: The ventricular cells are excitable and depolarizing randomly.



Rapid drop in cardiac output and death occurs if not quickly reversed

Rhythm



Rate? none



Regularity? irregularly irreg.



P waves? none



PR interval? none



QRS duration

wide, if recognizable



Interpretation? Ventricular Fibrillation

Asystole

5. 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.

 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 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.

 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.

Bundle branch block and hemiblock

• Left bundle branch block LBBB

• Right bundle branch block RBBB