Wide - Complex Tachycardia (WCT)
Transcription
Wide - Complex Tachycardia (WCT)
Wide-Complex Tachycardia (WCT) Rate ≥ 100bpm QRS width >120ms Monomorphic Polymorphic (more common) (less common) Supraventricular 1. Bundle-branch aberrancy 2. Metabolic or drug-induced 3. Antidromic AVRT Ventricular 1. Pacemaker 2. VT 3. AIVR Supraventricular 1. Afib with pre-excitation Ventricular 1. Vfib/flutter 2. Long QT 3. Brugada syndrome 4. Other (catecholamineinduced VT, short QT) Note: A therapy like verapamil can cure a patient with SVT but kill a patient with VT. Also treatment for conditions in a given box can vary, for example VT versus AIVR. Questions to answer immediately 1. Hemodynamically stable? Angina? (If not, immediate electrical cardioversion/defibrillation.) 2. Any history of structural heart disease? (If so, the etiology is almost certainly is ventricular.) 3. What did an old ECG show? (Identify baseline bundle-branch blocks and pre-excitation.) Common Misconceptions 1. VT is always hemodynamically significant (Incorrect, in general VT is as well tolerated as SVT.) 2. Thinking too much (Up to 70-80% of all WCT are VT.) On morning rounds you are reviewing telemetry: What is the rhythm? How do you describe the wide-complex beat? Cycle-length dependent aberrancy Cycle-length dependent aberrancy can produce isolated wide-complex beats which are supraventricular (like prior). Via concealed conduction, this phenomenon can produce runs of wide-complex, supraventricular beats (as below). At your VA clinic that afternoon, a 59-M w/ ESRD who missed 2 days of HD presents for an acute care visit with weakness. He is borderline tachycardic so you obtain an ECG: Any laboratory predictions? Do you admit this patient to the CCU or the MICU? Metabolic/drug effects on QRS width Tricyclic antidepressant toxicity Other drugs which block Na-channel can cause this too (class IA and IC antiarrhythmics, diphenhydramine, cocaine) That night on call a STEMI comes in and receives PCI. After the cath team and fellow have left the RN calls you for the following strip on the telemetry monitor: What is the rhythm? What treatment is needed? Later that call night your code pager goes off. Upon entering the patient’s room the monitor strip shows What is this rhythm? What treatment is indicated? After appropriate treatment you obtain a 12-lead ECG tracing: What is the unifying diagnosis? Your final call comes just before you are about to pass off the call pager. The ER has a young man who has palpitations and is dizzy. Thankfully he brought an old ECG of his, of which some representative beats are shown. His current 12lead ECG shows: What is the treatment of choice? Algorithm for monomorphic WCT Absence of precordial RS complex Presence of precordial RS complex Duration of precordial RS interval Measure from START of R-wave to NADIR of S-wave AV Dissociation QRS morphology in V1 and V6 In RBBB pattern first “rabbit ear” is taller in VT while second “rabbit ear” is taller in SVT. In LBBB pattern the time from R-wave start to S-wave nadir is short in SVT and long in VT. Other clues to VT • QRS duration: >140ms with RBBB morphology or >160ms with LBBB morphology suggests VT • QRS axis: “extreme” axis (right upper quadrant) suggests VT • Precordial concordance: negative concordance suggests VT, positive concordance suggests VT or AVNRT Energy levels for shocking • Polymorphic: unsynchronized 200 J • Monomorphic (unstable): synchronized 100 J • Monomorphic (stable): synchronized 50 J Case 1. 61-M w/ known CAD s/p multiple PCI presenting with chest pain Case 2. 63-M w/o manifest CAD presents with several hours of palpitations Answer Guide Case 1 (BJ 4/22/2007). RS complex present in V1 with duration about 120ms, AV dissociation present most clearly before/after 2 sinus beats, all of which point to VT EPS: spontaneously converted to SR, patient left hospital AMA before work-up could be initiated Case 2 (DT 8/6/2008). RS complex present in V5-6 with narrow duration, no AV dissociation, V1 morphology suggests aberrant RBBB although V6 has R<S, all of which suggest SVT EPS: adenosine revealed atrial flutter, underwent DCCV as rate was hard to control