What is the D.D and clinical significance?

1. Voltage discordance of precordial and limb leads in ECG
Ahmed ElBorae, MSc
Assistant lecturer of Cardiology, Cairo University
Differential diagnosis
&
clinical significance

2. Definition: Nadir-to-peak QRS amplitude less than 5 mm in all limb
leads and < 10 mm in all precordial leads
Low voltage ECG

3. What about voltage discordance ?
• Definition: Nadir-to-peak QRS amplitude less than 5 mm in all limb leads and >
10 mm in 2 or more contiguous precordial leads (V1 to V6)
• It is a well known marker of dilated cardiomyopathy (60% of voltage discordance
causes)
• Firstly described by Goldberger in 1982, the ECG triad (prominent precordial
amplitudes, relatively decreased limb lead voltages, and poor R progression) had
(sensitivity 70% and a high PPV 95%) in prediction of CHF and LV dysfunction
Journal of Electrocardiology 41 (2008) 281–286

4. Explanation
• Two reasons for high voltage precordial leads:
- 1. Chest leads are unipolar and picks up the electrical
activity directly beneath the lead
In dilated cardiomyopathy the enlarged heart brings the
myocardium closer to chest, this increases the
electromotive forces reaching the lead
-2. The enlarged LV increases the residual end systolic
and end diastolic volume , this increase in blood volume
increases the electrical conductivity and inscribes a high
voltage complex (Brody effect)
drsvenkatesan.com/2010/05/24/why-patients-with-dilated-cardiomyopathy-show-high-voltage-qrs-in-precardium-and-low-voltage-in-limb-leads/

5. Brody effect?
• The Brody effect : Increase QRS
amplitude induced by an increase in
ventricular preload and volume
explained by signal augmentation by
intra-cavitary blood (Brody, et al.
1956)
Clinical application: Decrease precordial ECG voltage during venesection

6. Explanation
On the other hand:
• The limb leads are bipolar, hence they record a smaller
voltage than chest leads
• In many patients with cardiomyopathy , the muscle
mass is replaced by fibrotic tissue (Interstitial fibrosis )
and this brings down the net electrical energy of the
myocardium
drsvenkatesan.com/2010/05/24/why-patients-with-dilated-cardiomyopathy-show-high-voltage-qrs-in-precardium-and-low-voltage-in-limb-leads/

7. A case report of cardiac amyloidosis presenting with similar ECG pattern
Possible explanation: Relative apical sparing by the disease, as well as
decreased cancellation of the opposing left ventricular walls could explain
Fused MRI-GLS images with examples of ECG waves on leads V1–V6. Segments of the LV are color-coded based on local strain values: red
corresponds to local strain ≤−16%; pink local strain >−16%. The solid yellow arrow represents the QRS axis. The dotted yellow arrows represent
direction of cancellation of electrical forces between opposing walls
Eötvös,
C.et
al.Medicina2021,57,
66

8. Thank You