SVT vs VT Flashcards

1
Q

What is one electrocardiographic feature that increases the likelihood of VT?

A

Absence of typical RBBB or LBBB morphology

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2
Q

What is extreme axis deviation in the context of VT?

A

QRS is positive in aVR and negative in I + aVF.

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3
Q

What defines broad complexes in VT?

A

Complexes > 160ms

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4
Q

What is AV dissociation?

A

P and QRS complexes at different rates.

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5
Q

What are capture beats?

A

Occurs when the sinoatrial node captures the ventricles, producing a QRS complex of normal duration.

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6
Q

What are fusion beats?

A

Occurs when a sinus and ventricular beat coincide to produce a hybrid complex.

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7
Q

What does positive concordance throughout the chest leads indicate?

A

Leads V1-6 show entirely positive (R) complexes suggestive of VT! (likewise negative)

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8
Q

What is Brugada’s sign?

A

The distance from the onset of the QRS complex to the nadir of the S-wave is > 100ms.

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9
Q

What is Josephson’s sign?

A

Notching near the nadir of the S-wave.

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10
Q

What is Marriott’s sign?

A

RSR’ complexes with a taller left rabbit ear.

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11
Q

What age increases the likelihood of VT?

A

Age > 35

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12
Q

What structural heart conditions increase the likelihood of VT?

A

Ischaemic heart disease, previous MI, congestive heart failure, cardiomyopathy.

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13
Q

What family history suggests a higher risk for VT?

A

Family history of sudden cardiac death.

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14
Q

What previous ECG findings suggest SVT with aberrancy?

A

Bundle branch block pattern with identical morphology.

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15
Q

What is one of the Brugada criteria for diagnosing VT?

A

Absence of an RS complex in all precordial leads.

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16
Q

What RS interval measurement indicates VT?

A

RS interval > 100ms in one precordial lead.

17
Q

What does AV dissociation indicate on an ECG?

A

Presence of hidden P waves at a different rate to the QRS complexes.

18
Q

What are the morphological criteria for VT in leads V1-2 with RBBB morphology?

A

Smooth monophasic R wave, notched downslope to the R wave, qR complex.

19
Q

What pattern in lead V6 is consistent with VT?

A

QS complex.

20
Q

What features in V1 indicate LBBB-like morphology for VT?

A

Initial R wave > 30-40 ms, notching or slurring of the S wave, RS interval > 60-70 ms.

21
Q

What does the Vereckei algorithm emphasize in diagnosing VT?

A

Examine the QRS complex in lead aVR.

22
Q

What does a dominant initial R wave in aVR suggest?

A

Indicative of VT.

23
Q

What is the likelihood of misdiagnosing VT based on published criteria?

A

High specificities but very low sensitivities (20-50%).

24
Q

What should be done if there is doubt about the rhythm?

A

Treat as VT.

25
Q

What is an RSR pattern in V1 strongly suggestive of?

A

SVT with RBBB