Arrhythmia's Pathophysiology, Presentation and Investigation

Question 1

<p>What is meant by normal sinus rhythm?</p>

Answer 1

<p>Normal heart rhythm with electrical activation beginning in the SA node</p>

Question 2

<p>Which lead is the best to assess rhythm?</p>

Answer 2

<p>Whichever lead that shows the P wave most clearly, usually limb lead 2 or V1</p>

Question 3

<p>What is the PR interval?</p>

Answer 3

<p>The time taken for the wave of depolarisation to travel from the SA node to the ventricular muscle (usualy no longer than 220 ms (6 boxes))</p>

Question 4

<p>What is meant by first degree heart block?</p>

Answer 4

<p>When there is a delay in the conduction pathway from the SA node to the ventricles</p>

<p>There is therefore a characteristic prolonged PR interval</p>

Question 5

<p>What are the casues of first degree heart block?</p>

Answer 5

<p>May be a sign of coronary artery disease, acute rheumatic carditis, digoxin toxicity or electrolyte disturbances.</p>

Question 6

<p>What is meant by second degree heart block?</p>

Answer 6

<p>When on intermittant occasion, excitation completely fails to pass through the AV node or the bundle of His</p>

Question 7

<p>What are the three different types of second degree heart block?</p>

Answer 7

<p>Mobitz type 1</p>

<p>Mobitz type 2</p>

<p>2:1 / 3:1 / 4:1 conduction</p>

Question 8

<p>What is mobitz type 1 heart block?</p>

Answer 8

<p>Progressivelengthening of the PR interval and then failure of conduction of an atrial beat, followed by a conducted beat with a shorter PR interval and then a repetition of this cycle</p>

Question 9

<p>What is mobitz type 2 heart block?</p>

Answer 9

<p>Most beats are conducted with a constant PR interval, but occasionally there is atrial depolarisation without a subsequent ventricular depolarization</p>

Question 10

<p>What is meant by2:1 / 3:1 / 4:1 conduction?</p>

Answer 10

<p>There may be alternate conducted and nonconducted atrial beats (or one conducted atrial beat and then two or three nonconducted beats), giving twice (or three or four times) as many P waves as QRS complexes. This is called ‘2:1’ (‘two to one’), ‘3:1’ (‘three to one’) or ‘4:1’ (‘four to one’) conduction</p>

Question 11

<p>What is meant by third degree heart block?</p>

Answer 11

<p>Complete heart block (third degree block) is said to occur when atrial contraction is normal but no beats are conducted to the ventricles. When this occurs the ventricles are excited by a slow ‘escape mechanism’ from a depolarizing focus within the ventricular muscle.</p>

<p></p>

<p>No relationship between P waves and QRS complexes</p>

<p>Abnormally shaped QRS complexes,</p>

<p>because of abnormal spread of depolarization from a ventricular focus</p>

Question 12

<p>What causes third degree heart block?</p>

Answer 12

<p>Complete heart block may occur as an acute phenomenon in patients with myocardial infarction (when it is usually transient) or it may be chronic, usually due to fibrosis around the bundle of His. It may also be caused by the block of both bundle branches.</p>

Question 13

<p>What causes third degree heart block?</p>

Answer 13

<p>Complete heart block is caused by the aging process, medicines, heart attacks, infiltrative heart diseases (amyloidosis,sarcoidosis), and infectious diseases (endocarditis,Chagas disease). It may also occur after heart surgery and can be present from birth (congenital)</p>

Question 14

What are the common causes of heart block?

Answer 14

Question 15

Where does mobitz 1 and mobitz 2 take place?

Answer 15

Question 16

<p>What are the presentations of third degree heart block?</p>

Answer 16

<p>Fainting, light headedness</p>

Question 17

<p>When is heart rhythm said to be arrhythmia?</p>

Answer 17

<p>When the depolarisation sequence begins somewhere outwith the SA node</p>

Question 18

<p>What can control the rhythm of contraction in the ventricles?</p>

Answer 18

<p>Most parts of the heart can depolarize spontaneously and rhythmically, and the rate of contraction of the ventricles will be controlled by the part of the heart that is depolarizing most frequently.</p>

Question 19

<p>What makes up suprventricular rhythm?</p>

Answer 19

<p>Sinus rhythm, atrial rhythm and junctional rhythm</p>

Question 20

<p>What is the rate of contraction in supraventricular / ventricular rhythm?</p>

Answer 20

<p>The atrial muscle or the area around the AV node (the junctional region) have spontaneous depolarization frequencies of about 50/min. If these fail, or if conduction through the His bundle is blocked, a ventricular focus will take over and give a ventricular rate of about 30/min.</p>

Question 21

Which rhythms have narrow/wide QRS complexes?

Answer 21

Question 22

<p>Why are escape rhythms called escape rhythms?</p>

Answer 22

<p>These slow and protective rhythms are called ‘escape rhythms’, because they occur when secondary sites for initiating depolarization escape from their normal inhibition by the more active SA node.</p>

Question 23

<p>What does atrial flutter look like on an ECG?</p>

Answer 23

<p>Atrial rate is greater than 250/min, and there is no flat baseline between the P waves, ‘atrial flutter’ is present</p>

Question 24

<p>What is meant by fibrillation?</p>

Answer 24

<p>When individual muscle fibres contract independently</p>

Question 25

<p>Explain why there are irregular QRS complexes present in atrial fibrillation</p>

Answer 25

<p>Depolarization spreads at irregular intervals down the His bundle. The AV node conducts in an ‘all or none’ fashion, so that the depolarization waves passing into the His bundle are of constant intensity. However, these waves are irregular, and the ventricles therefore contract irregularly.</p>

Question 26

<p>What is meant by supraventricular tachycardia?</p>

Answer 26

<p>Involves, atrial tachycardia, atrial flutter and nodal tachycardia</p>

Question 27

<p>Why are some of the P waves not followed by a QRS complex in atrial tachycardia?</p>

Answer 27

<p>In atrial tachycardia, the atria depolarize faster than 150/min</p>

<p>The AV node cannot conduct atrial rates of discharge greater than about 200/min. If the atrial rate is faster than this, ‘atrioventricular block’ occurs, with some P waves not followed by QRS complexes</p>

Question 28

<p>Explain the relationship between the P wave and the QRS complex in nodal tachycardia?</p>

Answer 28

<p>If the area around the AV node depolarizes frequently, the P waves may be seen very close to the QRS complexes, or may not be seen at all.The QRS complex is of normal shape because, as with the other supraventricular</p>

<p>arrhythmias, the ventricles are activated via the His bundle in the normal way.</p>

Question 29

<p>What is the diffrence between atrial tachycardia and heart block?</p>

Answer 29

<p>AV node working properly vs AV node and possible HIS bundle not working properly</p>

Question 30

<p>What is meant by theWolff–Parkinson–White syndrome?</p>

Answer 30

<p>There is an ‘accessory’ conducting bundle, which forms a direct connection between the atrium and the ventricle, usually on the left side of the heart, and in these bundles there is no AV node to delay conduction. A depolarization wave therefore reaches the ventricle early, and ‘pre-excitation’ occurs. The PR interval is short, and the QRS complex shows an early slurred upstroke called a ‘delta wave’. The second part of the QRS complex is normal, as conduction through the His bundle catches up with the pre-excitation.</p>

Question 31

<p>What is meant by ventricular tachycardia?</p>

Answer 31

<p>If a focus in the ventricular muscle depolarizes with a high frequency the rhythm is called ‘ventricular tachycardia’</p>

Question 32

<p>What is seen on an ECG of ventricular tachycardia?</p>

Answer 32

<p>Excitation has to spread by an abnormal path through the ventricular muscle, and the QRS complex is therefore wide and abnormal.</p>

<p>Wide and abnormal complexes are seen in all 12 leads of the standard ECG</p>

Question 33

<p>What is meant by sinus tachycardia?</p>

Answer 33

<p>Sinus tachycardia(also colloquially known assinus tachorsinus tachy) is asinusrhythm with an elevated rate of impulses, defined as a rate greater than 100 beats/min (bpm) in an average adult. </p>

<p></p>

<p>Three or less large squares between QRS complexes represents tachycardia on the ECG sheet usually</p>

Question 34

<p>How do you calculate heart rate in a patient with irregular qrs complexes?</p>

Answer 34

<p>Countthe number of QRS complexesover 30 large squares (this correspondst o 6 seconds) then multiply by 10 to give the number of beats over a minute.</p>

Question 35

<p>Define sinus bradycardia</p>

Answer 35

<p>Sinus bradycardiais asinusrhythm with a rate that is lower than normal. In humans,bradycardiais generallydefinedto be a rate of under 60 beats per minute.</p>

<p></p>

<p>This means a QRS complex is present every 5 boxes or more</p>

Question 36

<p>Define sinus arrest</p>

Answer 36

<p>Sinoatrial arrest is when thesinoatrial nodeof thehearttransiently ceases to generate the electrical impulses. It is defined as lasting from 2.0 seconds to several minutes. Since the heart contains multiple pacemakers, this interruption of thecardiac cyclegenerally lasts only a few seconds before another part of the heart, such as the atrio-ventricular junction or theventricles, begins pacing and restores the heart action</p>

Question 37

<p>What is meant by extrasytole or ectopic beat?</p>

Answer 37

<p>A premature contraction of the heart that is independent of the normal rhythm of the heart and that arises in response to an impulse in some part of the heart other than the normal impulse from the sinoatrial (SA) node. The extrasystole is followed by a pause, as the heart electrical system "resets" itself and the contraction following the pause is usually more forceful than normal. These more forceful contractions are frequently perceived aspalpitations.</p>

Question 38

<p>What is an atrial extrasystole seen as?</p>

Answer 38

<p>Looks similar to the atrial escape beat whereby an abnormal P wave is seen because excitation of the atrium has begun somewhere other than the SA node. The difference is that an extrasystole comes early and an escape beat comes late.</p>

Question 39

<p>What do junctional extrasystoles look like?</p>

Answer 39

<p>In a junctional extrasystole there is no P wave at all, or the P wave appears immediately before or immediately after the QRS complex</p>

Question 40

<p>Describe ventricular extrasystole</p>

Answer 40

<p>Ventricular extrasystoles have abnormal QRS complexes, which are typically wide and can be of almost any shape.</p>

<p>Ventricular extrasystoles are common, and are usually of no importance. However, when they occur early in the T wave of a preceding beat they can induce ventricular fibrillationand are thus potentially dangerous.</p>

Question 41

<p>Discuss the prevalence of af in england</p>

Answer 41

<p>It is estimated that 1.36 million people in England have AF. This is equal to 2.4% of the population. AF prevalence is higher in men than in women, 2.8% versus 2.0%. AF prevalence increases with age; 2.9% of the total estimated AF in the population is likely to occur in people aged under 45, 16.6% in people aged 45-65 and 80.5% in people aged over 65.</p>

Question 42

<p>What are the signs and symptoms of AF?</p>

Answer 42

<p>Atrial fibrillation (AF) usually causes the heart's lower chambers, the ventricles, to contract faster than normal.</p>

<p>When this happens, the ventricles can't completely fill with blood. Thus, they may not be able to pump enough blood to the lungs and body. This can lead to signs and symptoms, such as:</p>

<p><strong>Palpitations</strong>(feelings that your heart is skipping a beat, fluttering, or beating too hard or fast)</p>

<p><strong>Shortness of breath</strong></p>

<p><strong>Weakness</strong> or problems exercising</p>

<p><strong>Chest pain</strong></p>

<p><strong>Dizziness or fainting</strong></p>

<p><strong>Fatigue (tiredness)</strong></p>

<p><strong>Confusion</strong></p>

Question 43

<p>What is thetreatment for atrial fibrilaltion?</p>

Answer 43

<p>Rule out over active thyroid, medication to treat overactive thyroid may stop af</p>

<p></p>

<p><strong>Medicines</strong> to control af (sub divided into medication that can either restore heart rhythm or control the rate at which the heart beats.</p>

<p><strong>Anticoagulation</strong> to prevent the risk of stroke (warfarin or a newer type ofanticoagulant, such as dabigatran, rivaroxaban, apixaban or edoxaban)</p>

<p></p>

<p><strong>Cardioversion</strong> (It involves giving the heart a controlled electric shock to try to restore a normal rhythm.)</p>

<p><strong>Catheter ablation</strong> (a procedure that very carefully destroysthe diseased area of your heart and interrupts abnormal electrical circuits.)</p>

<p>(Catheters (thin, softwires)are guided through one of your veins into your heart, where they recordelectrical activity. When the source of the abnormality is found, an energy source, such as high-frequency radiowaves that generate heat, is transmitted through one of the catheters to destroy the tissue.)</p>

<p></p>

<p><strong>Pacemaker</strong></p>

<p></p>

<p></p>

Question 44

<p>What medications are able to restore normal rhythm?</p>

Answer 44

<p>Flecainide</p>

<p>beta-blockers, particularly sotalol</p>

<p>amiodarone</p>

<p>dronedarone(only for certain people)</p>

Question 45

<p>What drugs are used to control the rate of heart beat?</p>

Answer 45

<p>Beta blocker (bisoprolol or atenolol)</p>

<p>Calcium channel blocker (verapamil, diltiazem)</p>

<p>A medicine calleddigoxin may be added to help control the heart rate further. In some cases, amiodarone may be tried.</p>

Question 46

<p>WHat can cardioversion be used to treat?</p>

Answer 46

<p>Ventricular tachycardia</p>

<p>Supraventricular tachycardia due to reentry</p>

<p>Atrial fibrillation</p>

<p>Atrial flutter</p>

<p>Atrial tachycardia</p>

<p>Monomorphic VT with pulses</p>

Question 47

<p>f you've had atrial fibrillation for more than two days, cardioversion can increase therisk of a clot forming, how is clot formation avoided?</p>

Answer 47

<p>anticoagulant for three to four weeks before cardioversion, and for at least four weeks afterwards</p>

Question 48

<p>What are the indications for ICD therapy (implantable cardioverter-defibrillator)?</p>

Answer 48

<p>Cardiac arrest due to VF/VT not due to transient or</p>

<p>reversible cause eg early phase of acute MI</p>

<p>Sustained VT causing syncope or significant compromise</p>

<p>Sustained VT with poor LV function</p>

Question 49

<p>What are the indications for temporary pacing?</p>

Answer 49

<ul> <li>Intermittent or sustained symptomatic bradycardia, particularly syncope</li> <li>Prophylactic when patient at high risk for development of severe bradycardia eg 2nd or 3rd degree AV block, post anterior MI, even when asymptomatic</li></ul>

<p>(basically if there is bradycardia or risk of bradycardia)</p>

Question 50

<p>What are the indications for permanent pacing?</p>

Answer 50

<ul> <li>Symptomatic or profound 2nd/3rd degree AV block, particularly when causeunlikely to disappear</li> <li>Probably Mobitz type II 2nd/3rd degree AV block even if asymptomatic</li> <li>AV block associated with neuromuscular diseases after (or in preparation for) AV-node ablation</li> <li>Alternating RBBB/LBBB</li> <li>Syncope when bifascicular/trifascicular block and no other explanation</li> <li>Sinus node disease associated with symptoms</li> <li>Carotid sinus hypersensitivity/malignant vasovagal syncope</li></ul>

<p></p>

Question 51

<p>What is meant by bifasicular block?</p>

Answer 51

<p>Bifascicular block– The termbifascicular blockmost commonly refers to conduction disturbances below the atrioventricular (AV) node in which the right bundle branch and one of the two fascicles (anterior or posterior) of the left bundle branch are involved</p>

Question 52

<p>Define trifasicular block</p>

Answer 52

<p>Prolongation of thePR interval(first degree AV block)</p>

<p>Right bundle branch block</p>

<p>Eitherleft anterior fascicular blockor left posterior fascicular block.</p>

Question 53

<p>What is a bundle branch block?</p>

Answer 53

<p>When there is abnormal conduction through either the right or left bundle branches.</p>

<p>There isa delay in the depolarization of part of the ventricular muscle. The extra time taken for depolarization of the whole of the ventricular muscle causes widening of the QRS complex.</p>

<p>In the normal heart, the time taken for the depolarization wave to spread from the interventricular septum to the furthest part of the ventricles is less than 120 ms, represented by three small squares of ECG paper. If the QRS complex duration is greater than 120 ms, then conduction within the ventricles must have occurred by an abnormal, and therefore slower, pathway.</p>

Question 54

<p>What is the approach to assess ECG?</p>

Answer 54

<p>ARIBAR</p>

<p>A - Any electrical activity</p>

<p>R - Rate</p>

<p>I - Irregular or regular</p>

<p>B - QRS complexes <strong>B</strong>road or Narrow</p>

<p>A - Atrial activity?</p>

<p>R - Relationship between atrial acivity and ventricular activity?</p>

Question 55

<p>What are the four main types of supraventricular tachycardia?</p>

Answer 55

<p>atrial fibrillation,paroxysmal supraventricular tachycardia(PSVT),atrial flutter, andWolff-Parkinson-White syndrome</p>

Question 56

<p>What is the disease mechanism behind paroxysmal supraventricular tachycardia?</p>

Answer 56

<p>The underlying mechanism typically involves anaccessory pathwaythat results inre-entry.</p>

Question 57

<p>How is diagnosis of paroxysmal supraventricular tachycardia achieved?</p>

Answer 57

<p>Diagnosis is typically by anelectrocardiogram(ECG) which showsnarrow QRS complexesand a fast heart rhythm typically between 150 and 240beats per minute</p>

Question 58

<p>What is the initial treatment of paroxysmal supraventricular tachycardia?</p>

Answer 58

<p>Vasalva manouvre</p>