Approach to a patient<br />With <br />Narrow QRS complex <br />TACHYCARDIA<br />Dr.Nagula Praveen<br />24-08-2011<br />
My first CASE experience …<br /><ul><li>1.A 35 yr old female came to medicine OP with complaints of pounding sensation in the heart,dizziness.lightheadedness..the episode lasted for few minutes relieved spontaneously without any efforts..ending up in the patient passing urine after the absence of palpitations…on examination her heart heart was normal…there are no neck abnormalities…no other features..her BP is normal ..her thyroid status is normal ..What is the diagnosis was asked ?</li></li></ul><li>SUPRAVENTRICULAR<br />TACHYCARDIA<br />
CASE scenario<br /><ul><li>A 28 yr old woman has rapid palpitations accompanied by chest pain and dizziness while playing her cello.she is brought to an ED.she has a faint regular pulse of 180 bpm.her blood pressure is 100/70 mm Hg.cardiovascular signs reveals no signs of heart failure.an ECG show a regular tachycardia with a narrow QRS complex and no apparent Pwaves ..how should her case be managed?</li></li></ul><li>Clinically<br />Patient complains of recurrent palpitations,chestfullness,lightheadedness,presyncope,syncope.<br />Ppt factors may be present – exercise,caffeine,cigarettesmoking,alcohol.<br />h/o heart disease,pulmonarydisease,postAFablation.<br />CAUTION :H/O DIGOXIN USE <br />On examination– neck pounding –cannon waves “frog’s sign “ – practically pathognomic of AVNRT.<br />HR is a non specific feature in differentiating SVTs.<br />
STEP wise<br />Look for QRS duration.<br />QRS complex regular/irregular.<br />Then look for presence of p waves.<br />P waves morphology<br />P waves and QRS relationship 1:1<br />AV block present.<br />QRS alternation<br />Termination initiation of tachycardia.<br />Effect of BBB on tachycardia cycle length.<br />
Decision tree schema by BAR and colleagues <br />Ref–ncbl.org.in<br />
In brief from the diagram clues<br />Response to carotid sinus massage or adenosine –with termination of arrhythmia with Pwave –AVNRT with atrial premature beat .<br />Tachycardia persists with AV block –AT,AFL,SANRT<br />Pseudo r ‘ wave in V1 –AVNRT <br />SHORT RP interval – AVNRT,AVRT<br />Long RP interval – AT,SANRT,AVNRT atypical<br />
AVNRT<br />Presence of a narrow complex tachycardia with regular R-R intervals and no visible p waves.<br />P waves are retrograde and are inverted in leads II,III,AVF.<br />P waves are buried in the QRS complexes –simultaneous activation of atria and ventricles – most common presentation of AVNRT –66%.<br />If not synchronous –pseudo s wave in inferior leads ,pseudo r’ wave in lead V1---30% cases .<br />P wave may be farther away from QRS complex distorting the ST segment ---AVNRT ,mostly AVRT.<br />
AVRT<br />Typical – RP interval < PR interval<br />RP interval > 80 milli sec<br />Atypical –RP interval > PR interval<br />Concealed bypass tract – only retrograde conduction<br />Manifest bypass tract– both anterograde and retrograde.<br />Electrical alternans –the amplitude of QRS complexes varies by 5 mm alternatively.<br />Rate related BBB occuring and the rate of tachycardia is decreasing –then the bypass tract is on the same side of the block.<br />
WPW syndrome<br />Two types<br />Orthodromic<br />Antidromic<br />Antidromic is wide complex tachycardia<br />In NSR detected by delta wave.<br />Can ppt into AF and VF on use of AV nodal blockers<br />MEMBRANE ACTIVE ANTIARRHTYHMIC DRUGS are safe.<br />CONCEALED WPW syndrome – no delta wave .less risk of AF<br />
Focal Atrial Tachycardia<br />P wave morphology changes.<br />PR interval > 0.12 sec .<br />Second,third degree AV block can occur.<br />Tachycardia terminates with a qrs complex ..<br />Right atrial origin– p wave inverted in V1.<br />If biphasic in V1—initially positive then negative.<br />Upright in lead AVL <br />Opposite if of left atrial origin<br />Superior origin –upright p waves in inferior leads<br />Inferior origin –p waves are inverted in inferior leads.<br />
Multifocal Atrial Tachycardia<br />At least three consequtive p waves with different morphologies with a rate > 100 bpm to be present.<br />Isoelectric baseline between p waves.<br />Also called as choaticatrial tachycardia<br />Mostly seen in COPD ,electrolyte abn,theophylline<br />Rate usually does not exceed 130-140 bpm.<br />
SANRT<br />Microreentrant tachycardia<br />Usually precipitated and terminated by premature atrial complexes.<br />Atrial rate is usually 120-150 bpm.<br />IART - Large or small reentrant circuit.<br />AV block can occur.<br />
Junctionaltachycardias<br />Non paroxysmal – accelerated junctional rhythm<br />Rate < 100 bpm Usually junctional node 40-60 bpm<br />Paroxysmal or focal junctional tachycardia is rare –automaticity.<br />110-250bpm.<br />P waves may be before or after QRS complex<br />Infrequent and nonsustained episodes –no treatment<br />Acute termination of SVT and establish the mechanism of SVT in case of acute setting.<br />Long term goal is abolishing the arryhthmia substrate.<br />Precipitating factors – electrolyte imbalance,hypoxia,ischemia,hyperthyroidism to be sought out.<br />
A 12 lead ECG during tachycardia and NSR.<br />No delay in therapy if the mechanism of SVT is not known.<br />Perform CAROTID SINUS MASSAGE,or give 6mg bolus adenosine.<br />In case of severe hemodynamic compromise a synchronisedcardioversion to be given.<br />
Carotid sinus massage<br />Check for carotid bruit before massage.<br />At the level of cricoidcartilage,at the angle of mandible the carotid sinus is situated.<br />Gentle pressure is applied over the carotid sinus for 5 -10 seconds.<br />ECG recording to be present.<br />In case of no response – try on the other side.<br />Simultaneous pressure not to be applied both sides.<br />Alternative manuevres are valsalva,gagreflex,ice water pouring over the face. <br />
If SVT is suspected to be AVnode dependent – drug of choice is adenosine and CCBs verapamil and diltiazem.<br />Useful for sustained cases of AV node independent tachycardias.<br />But digoxin,BBs,CCBs better control of ventricular response in atrialtachycardias<br />Class I agents to be combined with AV nodal blocking drugs – to eliminate 1:1 conduction of atrial to ventricles.<br />
80% cases interrupted with a combination of CCBand BB in 2 hrs…</li></li></ul><li>Long term control of SVT <br />Frequency and severity of episodes.<br />LVF<br />Cost benefits of radiofrequency ablation over the pharmacotherapy .<br />Pharmacotherapy is considered in patients who defer catheter ablation,whom in which ablation failed,or carries a risk of AV block.<br />Multifocal atrial tachycardia<br />Trial and error <br />Accessory pathway – class Ia,Ic,III<br />AV node blocking drugs<br />Young patients – Ia drugs<br />Class I agents LVD < 35% not used.<br />
Adenosine<br /><ul><li>not to be used in bronchospastic pulmonary disease.
Potentiated by dipyradimole,carbamazepine –decrease dose to 3 mg. </li></li></ul><li>Other drugs<br /><ul><li>Calcium channel blockers,beta blockers ,digoxin are the next drugs to be used if not responded to adenosine
Usually 60 % cases respond to a dose of 6 mg and 95 % cases at 12 mg.
Type 1 a AAD, 1c,iii,AMIODARONE in refractory cases.
Beta blockers not to used IV in heart failure.
Long term treatment in case of recuurentepisodes,hemodynamic instability.</li></li></ul><li>Catheter guided Radiofrequency Ablation<br />Several multipolar catheters are introduced<br />High right atrium ,bundle of his ,RVapex,Coronary sinus.<br />Radiofrequency is delivered at the site of earlier activation <br />Success is defined by elimination of the tachycardia or loss of pre excitation.<br />90-98% success in AV node dependent <br />60-80% in case of AV node independent.<br />Cryoablation more useful…<br />
Catheter Ablation of Cardiac Arrhythmias.<br />
Pacemakers<br />Temporary role in case of digoxin toxicity.<br />Permanent in case of long term control <br />To terminate the tachycardia<br />Revert into sinus rhythm<br />Prevent the occurrence.<br />Overdrive suppression <br />RF induced atrial pacing are used<br />No role of surgery presently in PSVT rx .<br />
Some important points <br />Rxof PSVT given for patient comfort except in IHD,MS<br />When the QRS complex is wide and VT is mistaken as SVT with ABERRANT conduction IV verapamil – not recommended decreases BP.<br />If DC cardioversion to be avoided because of possible adverse response to digitalis adm …pacing Rt atrium and ventricle via temp pacing.<br />In WPW syndrome avoid VERAPAMIL,LIDOCAINE .<br />Avoid digoxin.<br />In SANRT ,IART –class IA,IC ,BB <br />SANRT –digoxin.<br />
Cont…<br />Rx of ectopic atrial tachycardia – consider digitalis toxicity,chronic lung disease,metabolicabn,electrolyteabnormalities,acute MI ----temporary pacing.<br />Unsuccessful is EC<br />Removal or reversal of inciting factor<br />Surgical excision of focus.<br />Rx of MAT –chronic lung disease,metabolic,rare is digitlais toxicity ---CCBS,BBs ..no role of cardioversion,devices ,surgery.<br />
<ul><li>In case of WPW syndrome symptomatic concealed or manifested ..and evidence of preexcitation on NSR …send the patient for catheter ablation…</li></li></ul><li>Our case <br /><ul><li>1. carotid sinus pressure
Special problems<br />1.Coexisting Double Tachycardias<br />May not be identified during noninvasive testing ..needs EP study.<br />Ex—typical AVNRT and AT.<br />Concentric –eccentric –concentric.<br />AVNRT –both APC,VPC <br />AT only APC<br />2.Pseudo AF- infrequent presentation of PSVT.<br />Occurs during onset and termination of tahcycardia.<br />Multiple accessory AV pathways.<br />In young who have AF without other risk factors.<br />5% of AVNRT.<br />Group beating is seen <br />
REFERENCES<br /><ul><li>CARDIOLOGY third edition –Michael. H.Crawford