SAQ 149 – Cardiology – wide complex tachycardia and paced rhythm PCI
Model Answer
Question 1. wide complex tachycardia and paced rhythm PCI.
a. ECG features
| ECG feature | SVT | VT |
|---|---|---|
| AV dissociation, more QRS than P waves | Rules out | Rules in |
| Captured beats | Rules out | Rules in |
| Fusion beats | Rules out | Rules in |
| QRS duration | <140 ms supports | >140 ms strongly supports |
| QRS axis | Usually normal | Leftward supports; northwest axis strongly supports |
| Concordance | Usually discordant | Positive or negative concordance supports |
| RS complex | May be present | Absence in precordial leads supports |
| R-R intervals | Usually regular | Often slightly irregular |
| R-S width >100 ms in one or more precordial leads | Against | Supports |
| RBBB pattern | Triphasic rSR in V1 or V6, R>S in V6 | Monophasic R or biphasic qR/QR/RS in V1, S>R or QS in V6 |
| LBBB pattern | No R in V1, small narrow R in V2, no slurring of S-wave downstroke, monophasic R in V6, septal Q in I and V6 | Broad R or wide R-S length >30 ms in V1/V2, notched S downstroke in V1/V2, >60 ms to nadir of S in V1/V2, qR or QS in V6 |
b. AICD indications
- Primary prevention in patients on optimal medical therapy with MI more than 40 days ago and EF <30%.
- Cardiomyopathy with EF <35%.
- HOCM.
- Brugada syndrome.
- Long QT with recurrent symptoms.
- Sustained VT or VF not in the peri-MI setting.
- Resuscitated cardiac death thought due to VT/VF.
- Syncope with structural heart disease and inducible VT/VF.
c. PCI indications in paced rhythm
- One or more Sgarbossa criteria.
- ST elevation >=5 mm in a negative QRS complex.
- ST elevation >=1 mm with a positive QRS complex.
- ST depression >=1 mm in any of V1-V3.
- Strong clinical features of prolonged ischaemic chest pain.
- Dynamic ECG changes suggestive of ischaemia.
- Positive troponin.
- Echo evidence of new regional hypokinesis in an appropriate area.
- Positive hot MIBI scan.
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