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Toronto Notes 2019 Arrhythmias
Table 6. Wide Complex Tachycardia: Clues for Differentiating VT vs. SVT with Aberrancy*
Cardiology and Cardiac Surgery C23
Clinical Clues
Presenting symptoms
History of CAD and previous MI
Physical exam
Cannon “a” waves Variable S1
Carotid sinus massage/adenosine terminates arrhythmia
Not helpful VT
VT SVT**
ECG Clues
AV dissociation
Capture or fusion beats
QRS width >140 msec
Extreme axis deviation superior axis)
(left or right
VT VT VT VT
VT
May suggest VT VT (polymorphic)
Positive QRS concordance
(R wave across chest leads)
Negative QRS concordance (S wave across chest leads)
Axis shift during arrhythmia
*If patient >65 yr and previous MI or structural heart disease, then chance of VT >95%
**May terminate VT in some patients with no structural heart disease
Torsades de Pointes
• avariantofpolymorphicVTthatoccursinpatientswithbaselineQTprolongation–“twistingofthepoints”
• lookslikeusualVTexceptthatQRScomplexes“rotatearoundthebaseline”changingtheiraxisand
amplitude
• ventricularrate>100bpm,usually150-300bpm
• etiology:predispositioninpatientswithprolongedQTintervals
■ congenital long QT syndromes
■ drugs: e.g. class IA (quinidine), class III (sotalol), phenothiazines (TCAs), erythromycin,
quinolones, antihistamines
■ electrolyte disturbances: hypokalemia, hypomagnesemia
■ nutritional deficiencies causing above electrolyte abnormalities
• treatment:IVmagnesium,temporarypacing,isoproterenolandcorrectunderlyingcauseofprolonged QT, electrical cardioversion if hemodynamic compromise
Figure 33. Torsades de pointes
Ventricular Fibrillation (VFib)
• chaoticventriculararrhythmia,withveryrapidirregularventricularfibrillatorywavesofvaryingmorphology
• terminalevent,unlessadvancedcardiaclife-support(ACLS)proceduresarepromptlyinitiatedto
maintain ventilation and cardiac output, and electrical defibrillation is carried out
• mostfrequentcauseofsuddendeath
• refertoACLSalgorithmforcompletetherapeuticguidelines
Figure 34. Ventricular fibrillation
Sudden Cardiac Arrest
Definition
• unanticipated,non-traumaticcardiacdeathinastablepatientwhichoccurswithin1hofsymptom onset; VFib is most common cause
Etiology
• primarycardiacpathology
■ ischemia/MI
■ LVdysfunction
■ severe ventricular hypertrophy ■ HCM
■ AS
■ congenital heart disease e.g. arrhythmogenic right ventricular dysplasia
■ mutations in cardiac ion channels e.g. long QT syndrome, Brugada syndrome
Arrhythmias that May Present as a Wide QRS Tachycardia
• VT
• SVT with aberrant conduction (rate related)
• SVT with preexisting BBB or nonspecific
intraventricular conduction defect
• AV conduction through a bypass tract
in WPW patients during an atrial tachyarrhythmia (e.g. atrial flutter, atrial tachycardia)
• Antidromic AVRT in WPW patients (see Pre-Excitation Syndromes, C21)
CCS Consensus Conference 2003: Assessment of the Cardiac Patient for Fitness to Drive and Fly – Executive Summary
Can J Cardiol 2004;20:1313-1323
In both primary and secondary prevention ICD patients with private driving licenses, no restrictions to drive directly following implantation or an inappropriate shock are warranted. However, following an appropriate shock these patients are
at an increased risk to cause harm to other road users and therefore should be restricted to drive for a period of 2 and 4 mo, respectively. In addition, all ICD patients with commercial driving licenses have a substantial elevated risk to cause harm to other road users during the complete follow-up after both implantation and shock and should therefore be restricted to drive permanently.
(A complete set of easy to access CCS Drive and Fly guidelines is available in the iCCS App available for iOS and Android platforms)