Approach to a patient with P wave abnormalities in ECG

1. Fundamentals of ECG
P wave abnormalities in ECG
Dr. Md.Toufiqur Rahman
MBBS, FCPS, MD, FACC, FESC, FRCP, FSCAI,
FCCP,FAPSC, FAPSIC, FAHA,FACP
Professor & head of Cardiology
CMMC, Manikganj
Ex professor of cardiology,
NICVD, Dhaka

2. Fundamentals of ECG
Approach to a patient with P wave abnormalities in ECG
o The P wave is the first positive deflection on the ECG
o It represents atrial depolarisation
o Duration: < 0.12 s (<120ms or 3 small squares)
o The P wave represents the spread of the electrical impulse through both atria.
o The electrical impulse begins in the SA node and depolarizes the right atrium and then the
left atrium.
o Thus, the first part of the P wave reflects right atrial activity, and the late portion of the P
wave represents electrical potential generated by the left atrium.

3. Fundamentals of ECG
FEATURES OF THE NORMAL P WAVE
It should be upright in leads I and II, as well as in the precordial
leads V3 through V6. Best seen in leads II and V1
 It is always inverted in aVR. Commonly biphasic in lead V1
 It is usually upright in aVF and V3, but occasionally a diphasic or flat P wave
may be seen.
 It is variable in leads III, aVL, V1, and V2: upright, inverted, or diphasic. (A P
or T wave that is partly above the baseline and partly below it is referred to
as diphasic.)
<3 small squares in duration
<2.5 small squares in amplitude

4. Fundamentals of ECG
Case-1
Case-1: A 58-year-old man presented to the emergency department
with a one-week history of left-sided weakness. Computed
tomography (CT) of his brain showed an infarct involving the right
putamen and internal capsule. He had the following ECG.

5. Fundamentals of ECG
Case -2
Case-2: A 26-year-old woman presented to the emergency department
with a three-day history of bilateral lower limb swelling and reduced
exercise tolerance. On examination, dual heart sounds
with a loud P2 was heard. Her lungs were clear on auscultation, and
there was bilateral lower limb oedema. She had the following ECG.

6. Fundamentals of ECG
Case-3
Case-3: A 52-year-old woman presented with complaints of general
malaise and a low-grade fever. She presented to an acute care clinic 3
weeks prior for a sore throat, which was diagnosed as strep throat
(streptococcal pharyngitis). Appropriately, she was started on oral
penicillin but admitted to not finishing the prescription since she “felt
better after 4 days of taking the antibiotic.”

7. Fundamentals of ECG
The Atrial Waveform – Relationship to the P wave
 Atrial depolarisation proceeds sequentially from
right to left, with the right atrium activated before
the left atrium.
 The right and left atrial waveforms summate to
form the P wave.
 The first 1/3 of the P wave corresponds to right
atrial activation, the final 1/3 corresponds to left
atrial activation; the middle 1/3 is a combination of the two.
 In most leads (e.g. lead II), the right and left atrial
waveforms move in the same direction, forming a
monophasic P wave.

8. Fundamentals of ECG
The Atrial Waveform – Relationship to the P wave
 However, in lead V1 the right and left atrial waveforms
move in opposite directions.
 This produces a biphasic P wave with the initial positive
deflection corresponding to right atrial activation and the
subsequent negative deflection denoting left atrial
activation.
 This separation of right and left atrial electrical forces in
lead V1 means that abnormalities affecting each
individual atrial waveform can be discerned in this lead.
 Elsewhere, the overall shape of the P wave is used to
infer the atrial abnormality.

9. Fundamentals of ECG
Normal P-wave Morphology – Lead II
The right atrial depolarisation wave (brown) precedes that
of the left atrium (blue).
The combined depolarisation wave, the P wave, is less
than 120 ms wide and less than 2.5 mm high.

10. Fundamentals of ECG
Right Atrial Enlargement – Lead II
In right atrial enlargement, right atrial depolarisation lasts longer than
normal and its waveform extends to the end of left atrial depolarisation.
Although the amplitude of the right atrial depolarisation current
remains unchanged, its peak now falls on top of that of the left atrial
depolarisation wave.
The combination of these two waveforms produces a P waves that is taller than
normal (> 2.5 mm), although the width remains unchanged (< 120 ms).

11. Fundamentals of ECG
Causes of Right Atrial Enlargement
The principal cause is pulmonary
hypertension due to:
 Chronic lung disease
(cor pulmonale)
 Tricuspid stenosis
 Congenital heart
disease (pulmonary
stenosis, Tetralogy of
Fallot)
 Primary pulmonary
hypertension

12. Fundamentals of ECG
Left Atrial Enlargement – Lead II
In left atrial enlargement, left atrial depolarisation lasts
longer than normal but its amplitude remains unchanged.
Therefore, the height of the resultant P wave remains
within normal limits but its duration is longer than 120
ms.
A notch (broken line) near its peak may or may not be
present (“P mitrale”).

13. Fundamentals of ECG
Causes of left atrial hypertrophy
In isolation:
 Classically seen
with mitral stenosis
In association with
 left ventricular
hypertrophy
 Systemic hypertension
 Aortic stenosis
 Mitral incompetence
 Hypertrophic
cardiomyopathy

14. Fundamentals of ECG
Common P Wave Abnormalities
Common P wave abnormalities include:
 P mitrale (bifid P waves), seen with left atrial
enlargement.
 P pulmonale (peaked P waves), seen with right
atrial enlargement.
 P wave inversion, seen with ectopic atrial and
junctional rhythms.
 Variable P wave morphology, seen in multifocal
atrial rhythms.

15. Fundamentals of ECG
P mitrale
The presence of broad, notched (bifid)
P waves in lead II is a sign of left atrial
enlargement, classically due to mitral
stenosis.

16. Fundamentals of ECG
P Pulmonale
The presence of tall, peaked P waves in
lead II is a sign of right atrial enlargement,
usually due to pulmonary
hypertension (e.g. cor pulmonale from
chronic respiratory disease).

17. Fundamentals of ECG
Inverted P Waves
 P-wave inversion in the inferior leads
indicates a non-sinus origin of the P waves.
 When the PR interval is < 120 ms, the origin
is in the AV junction (e.g. accelerated
junctional rhythm)

18. Fundamentals of ECGCase-1:
A 58-year-old man presented to the emergency department with a one-week history of left-sided
weakness. Computed tomography (CT) of his brain showed an infarct involving the right putamen and
internal capsule. He had the following ECG.
ECG showing------
o The presence of ‘P mitrale’ in multiple leads – inferior leads II, III and aVF, and also leads
V2, V3 and V4.
o The duration of the P wave is 0.12 s or longer, and it has a bifid appearance.
o In lead V1, a biphasic P wave with a wide and deep terminal negative deflection is seen.
o The rhythm is sinus.
The abnormalities are consistent with left atrial enlargement.

19. A 26-year-old woman presented to the emergency department with a three-day history of bilateral lower
limb swelling and reduced exercise tolerance. On examination, dual heart sounds with a loud P2 was
heard. Her lungs were clear on auscultation, and there was bilateral lower limb oedema. She had the following ECG.
ECG showing -------
The presence of The P waves are tall and peaked, with a height of 3 mm in lead II.
The rhythm is sinus.
The findings are consistent with the presence of right atrial
enlargement (‘P pulmonale’).
Fundamentals of ECGCase-2

20. Case-3: A 52-year-old woman presented with complaints of general malaise and a low-grade fever. She
presented to an acute care clinic 3 weeks prior for a sore throat, which was diagnosed as strep throat
(streptococcal pharyngitis). Appropriately, she was started on oral penicillin but admitted to not finishing
the prescription since she “felt better after 4 days of taking the antibiotic.”
ECG showing -------------
 Retrograde conduction of the atrium causing an inverted P wave, best observed in lead II.
 P waves are also inverted in multiple leads (III, aVF, V3 through V6).
 PR interval is short (0.10 seconds), which suggests a junctional
rhythm.
Fundamentals of ECGCase-3