Echo, MR, EKG, SVT Flashcards
What is the Brugada criteria used for?
stepwise approach for differentiating VT vs. SVT with aberrancy If any of the four criteria is positive –> VT if non of the criteria are positive –> SVT with abberancy
Define the Brugada Criteria?
- Absence of RS complex in all precordial leads
- R to S interval > 100ms in one precordial lead
- AV dissociation
- Morphology criteria for RBBB or LBBB present in precordial leads
*dominant R wave in V1 –> criteria for RBBB
*dominant S wave in V1 –> criteria for LBBB
*if any are positive –> VT
*all negative –> SVT
Common EKG features of VT:
- Positive or negative concordance throughout the chest leads, i.e. leads V1-6 show entirely positive (R) or entirely negative (QS) complexes, with no RS complexes seen.
- Brugada’s sign (The distance from the onset of the QRS complex to the nadir of the S-wave is > 100ms)
- AV dissociation (P and QRS complexes at different rates)
- Absence of typical RBBB or LBBB morphology
- Capture beats (occur when the sinoatrial node transiently ‘captures’ the ventricles, in the midst of AV dissociation, to produce a QRS complex of normal duration.)
- Fusion beats (occur when a sinus and ventricular beat coincides to produce a hybrid complex.)
- Josephson’s sign (Notching near the nadir of the S-wave -RSR’ complexes with a taller left rabbit ear. This is the most specific finding in favour of VT. This is in contrast to RBBB, where the right rabbit ear is taller.)
- Extreme axis deviation (“northwest axis”)
- Very broad complexes (>160ms)
- QRS is positive in aVR and negative in I + aVF.
EKG findings of LVH:
- increased amplitude (voltage) of QRS
- supported (and strengthened) by presence of secondary ST-T wave changes
- Other: left atrial abnormality, LAD, and/or prolonged intrinsicoid deflection, prominent U waves may be present
EKG Criteria for LVH (Sokolow and Lyone):
Precordial leads
- Sv1 and R v5 or v6 > 35 mm
- R v5 or v6 > 25 mm
Limb leads
-R aVL > 11 mm
EKG Criteria for LVH (Romhilt and Estes Point system)
**5 or more = LVH, 4 or more = probably LVH**
Amplitude (any of the following) = 3 points
- Any limb lead R or S > 20 mm
- Sv1 or Sv2 > 30 mm
- Rv5 or Rv6 > 30 mm
ST-T change = 3 points (1 with digitalis)
Left atrial abnormality = 3 points
Left axis deviation (-30 or more) = 2 points
Intrinsicoid deflection = 1 point
EKG Criteria for LVH (Cornell)
Men: Ravl + Sv3 > 28 mm
Women: Ravl + Sv3 > 20 mm
EKG Criteria for left atrial abnormality
- Prominent notching of P-wave (especially L2) with P-wave duration > 0.12s
- Leftward shift of P-wave axis
- Increased duration and depth of terminal negative portion of P in V1 ( > 0.04 mm-sec)
Key characteristics of RVH
- R/S ratio in V1 > 1 and R wave > 5mm
- QR in V1
- RAD
- Right atrial enlargement
-S1Q3T3 pattern and S1S2S3 pattern
*S1S2S3 pattern due to RVH = (SII > SIII)
EKG criteria for Right atrial enlargement
- peaked P (amplitude > 2.5 mm) in leads II, III, and aVF
- Rightward shift in P-wave axis ( > +75)
- Increased area ( >0.06 mm/sec or amplitude > 1.5 mm) of initial positive portion of P wave in V1
Differential diagnosis of RAD
- RVH
- Lateral wall MI
- Left posterior hemiblock
- COPD
- Normal Young Adult
Differential diagnosis: Prominent R wave or R/S ratio in V1
- RVH
- Ventricular Pre-excitation (WPW)
- Posterior wall MI
- Hypertrophic Cardiomyopathy
- If qR pattern, incomplete RBBB with septal MI
- Normal Variant
EKG findings: Acute PE
- Rightward shift of the QRS axis ( > 90 or indeterminate)
- S1Q3T3 pattern
- Incomplete or complete RBBB (often transient)
- ST-segment deviation (depression or elevation) in V1-V2
- Sinus tachycardia, atrial flutter, atrial fibrillation
RBBB diagnostic criteria
- Broad QRS > 120 ms
- RSR’ pattern in V1-V3 (M-shaped QRS complex)
- Wide, slurred S wave in the lateral leads (I, aVL, V5-V6)
Causes of RBBB
- RVT / cor pulmonale
- PE
- Ischemic heart disease
- Rheumatic heart disease
- Myocarditis or cardiomyopathy
- Degnerative disease of the conduction system
- Congenital heart disease (e.g. ASD)
Incomplete RBBB criteria
-RSR’ patterin in V1-V3 with QRS duration < 120 ms
*Normal variant often seen in children (of no clinical significance)
RBBB pathophysiology
- activation of the RV is delayed as depolarization has to spread across the septum from the LV
- LV is activated normally, meaning that the early part of the QRS is unchanged
- Delayed RV activation produces a secondary R wave (R’) in the right precordial leads (V1-V3) and a wide, slurred S wave in the lateral leads
- Delayed activation of the RV also gives rise to secondary repolarization
EKG findings: Ostium Primum ASD
-rSR’s’ in lead V1
+
-Left axis deviation
*Normal axis = Ostium secundum
*Low atrial rhythm = sinus venosus ASD
What is Ashman phenomenon (Ashman beat)?
- occurs when a premature supra ventricular beat occurs before the right bundle branch has recovered from its refractory period –> results in the PVC being displayed as RBBB
- frequently occurs with PAC’s, however can also be seen in A-fib, atrial tachycardia as R-R intervals can vary
- No clinical significance, patient’s may feel palpitations
What is the significance of ST-depression that occurs only in the recovery period?
same diagnostic accuracy as ST-segment depression during exercise
When does ST-elevation usually show up on ETT?
What does this mean?
- Can be arrythmogenic if exercise continues.
- Can localize site of myocardial ischemia (unlike ST-depression) and usually indicates high-grade stenosis
What EKG findings preclude interpretation of exercise EKG?
- Paced ventricular rhythm
- Pre-excitation (WPW)
- LBBB
- Reduce specicity –> ST-T abnormalities, Digoxin use, LVH