SVT vs VT Flashcards
What is one electrocardiographic feature that increases the likelihood of VT?
Absence of typical RBBB or LBBB morphology
What is extreme axis deviation in the context of VT?
QRS is positive in aVR and negative in I + aVF.
What defines broad complexes in VT?
Complexes > 160ms
What is AV dissociation?
P and QRS complexes at different rates.
What are capture beats?
Occurs when the sinoatrial node captures the ventricles, producing a QRS complex of normal duration.
What are fusion beats?
Occurs when a sinus and ventricular beat coincide to produce a hybrid complex.
What does positive concordance throughout the chest leads indicate?
Leads V1-6 show entirely positive (R) complexes suggestive of VT! (likewise negative)
What is Brugada’s sign?
The distance from the onset of the QRS complex to the nadir of the S-wave is > 100ms.
What is Josephson’s sign?
Notching near the nadir of the S-wave.
What is Marriott’s sign?
RSR’ complexes with a taller left rabbit ear.
What age increases the likelihood of VT?
Age > 35
What structural heart conditions increase the likelihood of VT?
Ischaemic heart disease, previous MI, congestive heart failure, cardiomyopathy.
What family history suggests a higher risk for VT?
Family history of sudden cardiac death.
What previous ECG findings suggest SVT with aberrancy?
Bundle branch block pattern with identical morphology.
What is one of the Brugada criteria for diagnosing VT?
Absence of an RS complex in all precordial leads.
What RS interval measurement indicates VT?
RS interval > 100ms in one precordial lead.
What does AV dissociation indicate on an ECG?
Presence of hidden P waves at a different rate to the QRS complexes.
What are the morphological criteria for VT in leads V1-2 with RBBB morphology?
Smooth monophasic R wave, notched downslope to the R wave, qR complex.
What pattern in lead V6 is consistent with VT?
QS complex.
What features in V1 indicate LBBB-like morphology for VT?
Initial R wave > 30-40 ms, notching or slurring of the S wave, RS interval > 60-70 ms.
What does the Vereckei algorithm emphasize in diagnosing VT?
Examine the QRS complex in lead aVR.
What does a dominant initial R wave in aVR suggest?
Indicative of VT.
What is the likelihood of misdiagnosing VT based on published criteria?
High specificities but very low sensitivities (20-50%).
What should be done if there is doubt about the rhythm?
Treat as VT.
