Transcript
ECG MCQs ELECTROCARDIOGRAM 1. Acute hyperkalemia is associated with which of the following electrocardiographic changes 1)Prolongation of the ST segment (2) Prominent U waves(3) A decrease in the PR interval(4) QRS widening Ans. 4 Hyperkalemia leads to partial depolarization of cardiac cells. As a result, there is slowing of theupstroke of the action potential as well as reduced duration of repolarization. The T wave becomespeaked, the QRS complex widens and may merge with the T wave (giving a sine-waveappearance), and the P wave becomes shallow or disappears. Prominent U waves are associated with hypokalemia; ST-segment prolongation is associated with hypocalcemia.(Ref. Harrison, 15thEdition, Vol. 1, Pg. 1269) 2. “Osborn wave” is seen in 1) Hyperthermia(2) Hypothermia(3) Hypercalcemia(4) Acutepericarditis Ans. 2 “Osborn wave” is a distinctive convex elevation of J point. J point is the iso electric point at theunction of end of QRS complex and beginning of S-T segment.(Ref. Harrison, 15th Edition, Vol. 1,Pg. 1269) 3. Which of the following is the primary sclero degenerative disease of conducting system: (1)Lev’s disease(2) Lenegre’s disease(3) Romano – Ward syndrome(4) William’s syndrome Ans. 2 In Lev’s disease, there is calcification and sclerosis of the fibrous cardiac skeleton, whichfrequently invol ves the aortic and mitral valves, the central fibrous body, and the summit of the ventricular septum. Lenegre’s disease appears to be a primary sclerodegenerative disease withinthe conducting system itself with no involvement of the myocardium or the fibrous skeleton of theheart.(Ref. Harrison, 15th Edition, Vol. 1, Pg. 1287) 4. With regard to supraventricular tachycardia, which is simplest for differentiating paroxysmalatrial tachycardia with block from atrioventricular nodal reentry tachycardia 1) Osler’smanoeuver(2) Digoxin level(3) Carotid sinus massage(4) Presence or absence of anginalsymptoms Ans. 3 Carotid sinus massage is simplest for differentiating paroxysmal atrial tachycardia (PAT) with block from atrioventricular nodal re-entry tachycardia (AVNRT). This maneuver has no effect onPAT except to increase the block temporarily, while it may have the effect of converting AVNRT.Osler’s maneuver consists of testing for palpability of a pulseless radial artery with the pressure of the blood pressure cuff raised above the systolic blood pressure. If present, Osler’s maneuverexplains systolic pseudohypertension. Digoxin level may be helpful in differentiating between thetwo, because digoxin toxicity is a cause of PAT; however, it is a “soft” association and serves only to rule out toxicity before further evaluation of the dysrhythmia 5. The site of origin of AV junctional complex is1) AV node(2) Bundle of His(3) Bundle Branch(right)(4) Left Bundle Branch Ans. 2 ForumsPre PG Entrance NEET 2013 All india Exam bestdoc Guest Forums Search ForumsRecent PostsResourcesMembersLog in or Sign up The site of srcin of AV junctional complex is thought to be in the bundle of HIS as the AV node in vivo possesses no automaticity. (Ref. Harrison, 15th Edition, Vol. 1, Pg. 1293) 6. The ‘J’ point on ECG is 1) End of Q wave and beginning of R wave(2) End of P wave and beginning of P–R interval(3) End of S wave and beginning of ST segment(4) End of PR intervaland beginning of R wave Ans. 3 The J point is the junction of end of QRS complex and beginning of ST segment. (Ref. Harrison,15th Edition, Vol. 1, Pg. 1293) 7. Every °C rise in temp causes an increase in the heart rate by------------ beats/min 1) 9 (2)8(3) 10(4) 12 Ans. 2 The sinus rate will increase by 8 beats per minute for every one-degree increase in temperature. A diminution in oxygen saturation, as occurs at high altitudes or in association with congenital heartdisease, will also cause a sinus tachycardia.(Ref. Schamroth, 7th Edition, Pg. 328) 8. Flutter waves are best seen in 1) Lead II(2) Lead V1(3) (1) + (2)(4) Lead aVL Ans. 3 Flutter waves are the regular, undulating closely placed waves seen in saw-tooth appearance inatrial flutter. These are best seen in std-lead II and lead V1.(Ref. Schamroth, 7th Edition, Pg. 340) 9. A 67 years old man who has experienced recurrent episodes of dizziness over the last severalmonths is admitted to the hospital because of fainting episode. No evidence of acute myocardialinfraction is documented. On the evening of admission, the patient tells his nurse thatapproximately 10 min earlier, he experienced several minutes of dizziness. His current rhythmappears to be normal sinus; however, a monitoring strip obtained at the time of this episodereveals absent QRS complexes every third beat. The PR interval, while slightly prolonged, isconstant from beat to beat. P waves are present at regular intervals. Which of the following is themost appropriate therapeutic action : (1) Insertion of permanent cardiac pacemaker(2) Insertionof temporary cardiac pacemaker followed by insertion of permanent cardiac pacemaker(3) Administration of atropine, 2 mg IV(4) No specific therapy is required for this benign arrhythmia Ans. 1 The electrocardiogram discloses sudden failure of atrial ventricular conduction without apreceding change in the PR interval, Mobitz type II second-degree AV block, which usually reflectssignificant disease of the conduction system. It may occur after a significant anterior myocardialinfarction or in Lev’s disease, which involves calcification and sclerosis of the fibrous cardiacskeleton (frequently involving the aortic and mitral valves), or Lenegre’s disease, which involvesonly the conducting system. Mobitz type II block is inherently unstable and tends to progress tocomplete heart block with a slow, lower escape pacemaker. Therefore, pacemaker implantation isnecessary in this condition, particularly if the patient is symptomatic, as in this case.(Ref.Harrison, 15th Edition, Vol.1, Pg. 1287) 10. The combination of right axis deviation + left ventricular diastolic overload with atrialfibrillation is suggestive of 1) Mitral stenosis(2) Mitral incompetence(3) Aortic stenosis(4)Pulmonary incompetence Ans. 2 Electrocardiographic combinations Suggested diagnosis 1. Atrial fibrillationRight axis deviation Mitral stenosis 2. ‘Left atrial’ P waveRight axis deviation Mitral stenosis 3. Atrial fibrillationRight axis deviationLeft ventricular diastolic overload Mitral incompetence 4. Very tall ‘right atrial’ P waves in standard lead IIFirst-degree AV blockNormal QRS axisTricuspid stenosis 5. ‘Left atrial’ P waveLeft ventricular systolic overload Hypertensive heart disease (Ref. Schamroth, 7th Edition, Pg. 440) 11. The following are true about the position of heart in dextroversion, EXCEPT 1) Left ventricleis anterior(2) Right ventricle is posterior (3) Right atrium is posterior(4) Left atrium is anterior Ans. 4 DIFFERENCES BETWEEN DEXTROVERSION AND DEXTROCARDIA DextroversionDextrocardia 1. Left ventricle Anterior On the right side 2. Right ventricle Posterior On the left 3. Left atrium On the left Posterior 4. Right atrium Posterior On the left 5. Aorta Left side Right side 6. Venae cavae Right side Left side (Ref. P. J. Mehta, 3rd Edition, Pg. 42) 12. U wave is inverted in all, EXCEPT 1) Lead II, III(2) Acute pulmonary embolism(3) Acutemyocardial infarct(4) Lead V5, V6 Ans. 4 The U wave represents the slow repolarisation of the Purkinje’s fibres, the papillary muscles or the ventricular septum. It follows the T wave and precedes the P wave of the next cycle. It has thesame polarity as the T wave and hence it is upright in most of the leads.U waves tend to beinverted in II, III, V1 and V2. It is transiently inverted during angina, acute pulmonary embolism,left ventricular overload, digitalis effect and sometimes in myocardial infarction. In myocardialinfarction most of the changes may revert to normal and yet inverted U waves may persist. (Ref. P.J. Mehta, 3rd Edition, Pg. 22-23) 13. All are ECG features of pulmonary embolism, EXCEPT 1) ST segment elevation inprecordial leads(2) Transient RBBB(3) T wave inversion in lead III and aVF(4) Absent ‘P’ waves inlead II and III Ans. 4 The typical pattern of pulmonary embolism is as follows1) A Q wave develops with ST elevationand shallow T wave inversion in leads III and aVF(2) A prominent S wave with slightly depressedST segment and upright T wave occurs in leads I and II. This produces the classical SI QIII TIIIpattern associated with pulmonary embolism.(3) In the precordial leads there may be ST elevation with T wave inversion over right ventricular leads and prominent S wave over left ventricularleads.(4) Transient right bundle branch block may occur.(Ref. P. J. Mehta, 3rd Edition, Pg. 100) 14. Cardiotoxicity caused by radiotherapy and chemotherapy is best detected by 1) ECHO(2)Endomyocardial biopsy(3) ECG(4) Radionucleide scan Ans. 2 Myocardial fibrosis, as caused by radiotherapy, cannot be best diagnosed by anything less than atissue or endomyocardial biopsy.(Ref. Harrison, 15th Edition, Vol. 1) 15. A chronic alcoholic develops palpitations suddenly after alcohol binge. Which of the followingarrythmia is most commonly associated with alcohol binge in the alcoholics 1) Ventricularfibrillations(2) Ventricular premature contractions(3) Atrial flutter(4) Atrial fibrillation Ans. 4 Whenever the pulse is irregularly irregular, atrial fibrillation is almost always thediagnosis.Arrhythmia occurring after a drinking binge is known as Holiday heartsyndrome.Arrhythmias to follow drinking binge in order of frequency :- Atrial fibrillation (MC)- Atrial flutter- Ventricular premature contractionsThe most common cardiac effect of chronicdrinking is dilated cardiomyopathy.(Ref. Harrison, 15th Edition, Vol. 1, Pg. 1360) 16. All of the following are true about ASD, EXCEPT 1) Right atrial hypertrophy(2) Right ventricular hypertrophy(3) Pulmonary hypertension(4) Left atrial hypertrophy Ans. 4 LA has two outflow tracts in ASD, viz.- Into L.V. through mitral valve- Into R.A. through ASDWithtwo outflow tracts, the resistance against which the L.A. has to pump is decreased. This explainsabsence of L.A. hypertrophy.Right atrial load, however is increased and so is the load to R.V. andPulmonary vessels. This explains R.A. and R.V. hypertrophy as well as pulmonary hypertension.ECG with right axis deviation and R.V.H. suggests ostium secundum defect. Left axisdeviation suggests ostium primum defect.(Ref. Ghai, 5th Edition, Pg. 296) 17. All of the following are common causes of Atrial fibrillation, EXCEPT 1) Digitalis(2)Thyrotoxicosis(3) Hypertension(4) Rheumatic fever Ans. 3 CAUSES OF ATRIAL FIBRILLATION Common Uncommon 1. Rheumatic fever 1. Constrictive pericarditis 2. Coronary heart disease 2. Cor-pulmonale 3. Thyrotoxicosis 3. Bronchogenic carcinoma 4. Diphtheria 4. A.S.D. 5. Drugs. Digitalis, propranolol adrenaline, emetine 5. Hypertension 6. Excessive use of tea, coffee, tobacco and alcohol 6. Lone atrial fibrillation 7. W.P.W. Syndrome 8. Hypothermia 9. Diseased sino-atrial and atrio-ventricular nodes (Ref. Harrison, 15th Edition, Vol. 1, Pg. 1295) 18. “Camel – Hump” P wave is seen in 1) Cardiac pacing(2) Left atrial enlargement(3)Constrictive pericarditis(4) All of the above Ans. 2 With left atrial enlargement, the P wave is prolonged due to delay of the left atrial or terminalcomponent of the P wave. The characteristic features will manifest in standard lead II, or instandard lead I or even lead AVL when there is left axis deviation of the P wave. The P wave shows:(i) a double peaked, notched or ‘camel humped’ P wave, and (ii) an increased duration of the P wave to longer than 0.11 sec. The duration of the notch – the distance between the ‘camel humps’– is longer than 0.04 sec. (Ref. Schamroth, 7th Edition, Pg. 52) 19. In the absence of structural heart diseases, which of the following is more common 1)RBBB(2) LBBB(3) AV junctional block(4) All of the above Ans. 1 In subjects without structural heart diseases, RBBB is seen more commonly than LBBB. AV unctional block is less common among these.(Ref. Harrison, 15th Edition, Vol. 1, Pg. 1266) 20. If Mobitz type II block occurs with a normal QRS durations, the block is likely to be situated at 1) AV node(2) Bundle of His(3) Purkinje fibres(4) All of the above Ans. 2 In Mobitz type II second degree AV block, conduction fails suddenly and unexpectedly without apreceding change in PR interval. It is generally due to disease of the His Purkinje system and ismost often associated with a prolonged QRS duration. When Mobitz type II block occurs with anormal QRS duration, an intra-His site of block should be expected.(Ref. Harrison, 15th Edition, Vol. 1, Pg. 1287) 21. A 60 years old man complains that for an hour, he has been experiencing palpitations, a feelingof unease, and vague chest pain. The peripheral pulse is difficult to count because of the unevenamplitude and time span between beats; apical rate is 130 per minute, with only one heart soundevidence in many of the beats, blood pressure (BP) is 115 – 130/ 60 – 75, imprecise because theKorotkoff sound are inconsistent (his usual BP is 145/85). An ECG shows an electrical rate of 150, with clearly identifiable narrow QRS complexes, but an irregular baseline and no identifiable P waves. What is the first therapeutic goal in the treatment of this condition?(1) Achieve an increasein the BP(2) Obtain relief of chest pain(3) Convert the rhythm to regular sinus rhythm(4) Obtainreduced ventricular response Ans. 4 Obtaining reduced ventricular response is the first therapeutic goal in the treatment of this man, who is having a typical attack of acute atrial fibrillation. The rapid ventricular response is thegreatest threat at the outset. Conversion to regular sinus rhythm can await rate control. Agentsthat can achieve rate reduction rapidly include digoxin, beta-blocking agents, and calciumchannel-blocking agents. Calcium channel blocking agents afford a fair chance of conversion toregular sinus rhythm; beta-blocking agents should be avoided if the ventricular rate is £ 80 perminute. If rate control is not established quickly, the criterion for hospitalization in this case is
