A 28-year-old woman presented to the emergency department with rapid palpitations, chest pain, and dizziness while playing cello. On examination, she had a regular pulse of 180 bpm and a blood pressure of 100/70 mm Hg with no signs of heart failure. An ECG showed a regular narrow-complex tachycardia without visible P-waves, consistent with supraventricular tachycardia.
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Approach to a case of narrow complex tachycardia
1. Approach to a patient With Narrow QRS complex TACHYCARDIA Dr.Nagula Praveen 24-08-2011
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4. STEP wise Look for QRS duration. QRS complex regular/irregular. Then look for presence of p waves. P waves morphology P waves and QRS relationship 1:1 AV block present. QRS alternation Termination initiation of tachycardia. Effect of BBB on tachycardia cycle length.
8. In brief from the diagram clues Response to carotid sinus massage or adenosine –with termination of arrhythmia with Pwave –AVNRT with atrial premature beat . Tachycardia persists with AV block –AT,AFL,SANRT Pseudo r ‘ wave in V1 –AVNRT SHORT RP interval – AVNRT,AVRT Long RP interval – AT,SANRT,AVNRT atypical
17. AVNRT Presence of a narrow complex tachycardia with regular R-R intervals and no visible p waves. P waves are retrograde and are inverted in leads II,III,AVF. P waves are buried in the QRS complexes –simultaneous activation of atria and ventricles – most common presentation of AVNRT –66%. If not synchronous –pseudo s wave in inferior leads ,pseudo r’ wave in lead V1---30% cases . P wave may be farther away from QRS complex distorting the ST segment ---AVNRT ,mostly AVRT.
25. AVRT Typical – RP interval < PR interval RP interval > 80 milli sec Atypical –RP interval > PR interval Concealed bypass tract – only retrograde conduction Manifest bypass tract– both anterograde and retrograde. Electrical alternans –the amplitude of QRS complexes varies by 5 mm alternatively. Rate related BBB occuring and the rate of tachycardia is decreasing –then the bypass tract is on the same side of the block.
30. WPW syndrome Two types Orthodromic Antidromic Antidromic is wide complex tachycardia In NSR detected by delta wave. Can ppt into AF and VF on use of AV nodal blockers MEMBRANE ACTIVE ANTIARRHTYHMIC DRUGS are safe. CONCEALED WPW syndrome – no delta wave .less risk of AF
37. Focal Atrial Tachycardia P wave morphology changes. PR interval > 0.12 sec . Second,third degree AV block can occur. Tachycardia terminates with a qrs complex .. Right atrial origin– p wave inverted in V1. If biphasic in V1—initially positive then negative. Upright in lead AVL Opposite if of left atrial origin Superior origin –upright p waves in inferior leads Inferior origin –p waves are inverted in inferior leads.
40. Multifocal Atrial Tachycardia At least three consequtive p waves with different morphologies with a rate > 100 bpm to be present. Isoelectric baseline between p waves. Also called as choaticatrial tachycardia Mostly seen in COPD ,electrolyte abn,theophylline Rate usually does not exceed 130-140 bpm.
42. SANRT Microreentrant tachycardia Usually precipitated and terminated by premature atrial complexes. Atrial rate is usually 120-150 bpm. IART - Large or small reentrant circuit. AV block can occur.
43. Junctionaltachycardias Non paroxysmal – accelerated junctional rhythm Rate < 100 bpm Usually junctional node 40-60 bpm Paroxysmal or focal junctional tachycardia is rare –automaticity. 110-250bpm. P waves may be before or after QRS complex Infrequent and nonsustained episodes –no treatment Acute termination of SVT and establish the mechanism of SVT in case of acute setting. Long term goal is abolishing the arryhthmia substrate. Precipitating factors – electrolyte imbalance,hypoxia,ischemia,hyperthyroidism to be sought out.
45. A 12 lead ECG during tachycardia and NSR. No delay in therapy if the mechanism of SVT is not known. Perform CAROTID SINUS MASSAGE,or give 6mg bolus adenosine. In case of severe hemodynamic compromise a synchronisedcardioversion to be given.
46. Carotid sinus massage Check for carotid bruit before massage. At the level of cricoidcartilage,at the angle of mandible the carotid sinus is situated. Gentle pressure is applied over the carotid sinus for 5 -10 seconds. ECG recording to be present. In case of no response – try on the other side. Simultaneous pressure not to be applied both sides. Alternative manuevres are valsalva,gagreflex,ice water pouring over the face.
47. If SVT is suspected to be AVnode dependent – drug of choice is adenosine and CCBs verapamil and diltiazem. Useful for sustained cases of AV node independent tachycardias. But digoxin,BBs,CCBs better control of ventricular response in atrialtachycardias Class I agents to be combined with AV nodal blocking drugs – to eliminate 1:1 conduction of atrial to ventricles.
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50. Pharmacologic Agents for Short-Term Treatment of Supraventricular Tachycardia (SVT). Delacrétaz E. N Engl J Med 2006;354:1039-1051.
77. Pacemakers Temporary role in case of digoxin toxicity. Permanent in case of long term control To terminate the tachycardia Revert into sinus rhythm Prevent the occurrence. Overdrive suppression RF induced atrial pacing are used No role of surgery presently in PSVT rx .
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79. Some important points Rxof PSVT given for patient comfort except in IHD,MS When the QRS complex is wide and VT is mistaken as SVT with ABERRANT conduction IV verapamil – not recommended decreases BP. If DC cardioversion to be avoided because of possible adverse response to digitalis adm …pacing Rt atrium and ventricle via temp pacing. In WPW syndrome avoid VERAPAMIL,LIDOCAINE . Avoid digoxin. In SANRT ,IART –class IA,IC ,BB SANRT –digoxin.
80. Cont… Rx of ectopic atrial tachycardia – consider digitalis toxicity,chronic lung disease,metabolicabn,electrolyteabnormalities,acute MI ----temporary pacing. Unsuccessful is EC Removal or reversal of inciting factor Surgical excision of focus. Rx of MAT –chronic lung disease,metabolic,rare is digitlais toxicity ---CCBS,BBs ..no role of cardioversion,devices ,surgery.
108. Special problems 1.Coexisting Double Tachycardias May not be identified during noninvasive testing ..needs EP study. Ex—typical AVNRT and AT. Concentric –eccentric –concentric. AVNRT –both APC,VPC AT only APC 2.Pseudo AF- infrequent presentation of PSVT. Occurs during onset and termination of tahcycardia. Multiple accessory AV pathways. In young who have AF without other risk factors. 5% of AVNRT. Group beating is seen