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Figure lii

In right atrial hypertrophy the (initial) right atilal component ci the P wave is

increased in magnitude and In duration. The resultant efect on the P wave is an

increase In the P wave height but not In its duration. a) The resultant P wave In Lead

Ills abnormally tall and Is pointed. b) The resultant P wave in Lead V has anabnormally tall (Initial) positive component.

!ormal P wave In ii " right and le#t atrial components.

The P wave In II in right atrial hypertrophy " right and le#t atrial components. The

right atrial c$mponent is increased.

The P wave in II in right atrial hypertrophy is abnormally tall.

!ormal P wave in V" right and le#t atrial components.

The P wave in V in right atrial hypertrophy " right and le#t atrial components. Theright abial component is increased%

The P wave in V in right atrial hypertrophy has a tall initial positive component.

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The primary electrocardiographic change in Fight atdal hypertrophy is there#ore an

Increase In the voltage o# the P wave in Lead II and an increase in the voltage o# the

initial positive part o# the P wave In V. There Is a good deal o# variation in the

&omlnant dIretion o# right atrial depolarisatlon In the hori'ontal plane and as a

result o# this changes In the P wave height in V do not reliably $ccur in right atrial

hypertrophy. The diagnosis o# right atrial hypertrophy can there#ore only sa#ely bemade #rom the P waves in the #rontal plane leads. Lead II usually shows the changes

best n e*ample Is shown In FIgure +. The ,-$ in Figure + would be reported

as tollows/0inus rhythm. The mean #rontal plane 120 a*is Is 3456. There Is right

ventricular hypertrophy% right atrial hypertrophy and cloc7wise cardiac rotation8.

Figure +

ThereI9 an degree o# right a*is deviation (345:) and a dominant wave in V.

Them Is thus right ventricular hypertropl. The P waves are tall and pointed in l..ead

It and are In e*cess o# ;mm. There Is thus right atrie.I hypertrophy. 2ight atriai

hypertrophy very #re

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Criterion for right atrial hypertrophy

The P wave height Is ;mm or more in Leads ii% III or aVF (Leads III and aVF are

Included because the P wave vector is sometimes directed more closely towards

either o# these leads than along Lead II% i.e. the P wave a*is is o#ten 3=56 or more

positive than this).

Associated ndIngs

in association with right atrial hypertrophy% the positive part o# the P wave in V is

o#ten greater than .5mm tail. There is usually evidence o# right ventricular

hypertrophy. There is o#ten also a prominent atrial repolarisation wave (see pages

44 and 4=).

Clinical SIgnicance

s indicated earlier% the electrocardiographic >nding o# /right atrial hypertrophy8

strictly spea7ing only de>nes the presence o# right atrial abnormality. -hanges

similar to those in hypertrophy also occur in ischaemla or in#arction o# the right

atrium although the latter two are rare clinical events. The presence o# associated

right ventricular hypertrophy ma7es it much more li7ely that the right atriai

hypertrophy pattern on the electrocardiogram does indicate true hypertrophy o# the

right atrium. 2ight atrial hypertrophy occurs in all conditions which give rise to right

ventricular hypertrophy and ih addition it occurs in tricuspid stenosis.

Left Atrlat Hypertrophy

The electrocardiographic changes produced by le#t atriai hypertrophy are those

changes produced by an increase In the voltage and duration o# the le#t atrial

depolarisation wave. 0ince the terminal part o# the normal P wave is produced by

le#t atrial depolarlsation% It #ollows that the total P wave duration is prolonged in le#t

atrial hypertrophy.

In addition% the P wave tends to be bi>d in Lead ii and biphasic in V (Figure ;). In

V the area o# the (terminal) negative component e*ceeds the area o# the (initial)

positive component. n e*ample o# le#t atrial hypertrophy is shown in Figure ?.

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The ,-CDn Figure ? would be reported as #ollowsE /0inus rhythm. The mean

#rontal plane 120 a*is is 3=5@. Th P waves are broad and bit Id in Lead Iland there

Is a dominant negative mponent to the P wave in V%. The changes are Indicative o#

le#t atrial hypertrophy (strictly:le#t atrial abnormality8). In other respects the record

is within normal limits:.

Figure ?

The rGythm is sinus. P waves are bi>d in Lead II. The P wave duration in Lead II is

prolonged at @.5 sec (best seen in the second Twave in Lead II). The P waves nVare clearly biphasic. In this lead there isa small% brie# (and rather sharp loo7ing)

initial positive component lollowed by a deeper and very much broader negative

component. The area o# the negative component clearly e*ceeds that o# the positive

component.

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-riteria #or le#t atrial hypertrophy

. The P wave is notched and e*ceeds @.+ sec in duration in Leads% Ii% aVF or aVL.

+. The P wave In V has a dominant negative component (I.e. either It is entirely

negative or alternatively the area o# the (terminal) negative component e*ceeds

that o# the (initial) positive component).

(,ither criterion suggests the diagnosis. I# both are satis>ed the diagnosis ismore

li7ely still).

Features commonly associated with left atrial hypertrophy

Dust as right atrial hypertrophy is #re

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The diagnosis o# biatrial hypertrophy is not as dicult as the diagnosis o#

b7ventricuar hypertrophy since the hypertrophy o# each individual atrium afects

predominantly a diferent part o# the P wave whereas hypertrophy o# each individual

ventricle afects the same part o# the $20 comple*. Jiatrial hypertrophy may

there#ore be diagnosed whenever the criteria #or both le#t and right atrial

hypertrophy are #ul>lled.

-linical 0igni>cance

Jiatrial enlargement is #ound in conditions giving rise to biventricular enlargement.

This includes congenital heart disease% hypertrophic cardiomyopathy and pulmonary

hypertension occurring either with aortic

valve disease or with mitral incompetence. The reservations e*pressed about the

use o# the term /atriai hypertrophy8 with re#erence to hypertrophy o# individual atria

apply elled the more

li7ely the diagnosis becomes).

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Atrial epolarisatlon !a"e

It was pointed out (page 5) that electrical recovery o# myocardium must occur

#ollowing depolarisation o# that myocardium be#ore any subse

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prominent Ta wave

Prominent Ta wave which is% as usual% partly obscured by the 120 comple*. t >rst

sight there is 0T segment depression. ore care#ul inspection reveals: that the

depression begins be#ore the 120 comple*. It there#ore cannot be 0T depression. It

is a prominent Ta wave%

Causes of #rominent Atrial epolarisatlon !a"es

Jy #ar the commonest cause o# an e*aggerated Ta wave is sinus achycardia. n

e*ample is sbswn in Figure 4. The ,CC o# Figure 4 would be reported as

#ollows/0inus tachycardiai. 2ate 45mm. Prominent atrial repolarisatlon wave

simulating 0Tdepression in some leads. llowing #or the heart rate% the record is

within normal limits8.

Prominent Ta waves may also occur in right atrial hypertrophy. Closs inspection o#

Figure + shows a prominent Ta wave well seen in Leads II and aVF. Prominent Ta

waves also occur in atrial In#arction (see page QQ).

2arely. a normal Ta wave can be seen in cases o# complete heart bloc7 when the$20 comple* does not obscure the wave.

Figure 4

+lead electrocardiogram ta7en Dust a#ter the completion o# an e*ercise test. The

rhythm Is sinus tachycardla and the heart rate is 45mm. There Is apparent 0T

depression in I% II% aVF and V?V4% but closer Inspection (especially in II where the T

and Ta vectors are usually best seen) reveals that the negativity begins be#ore the

$20 comple*es. It is a prominent Ta wave. There is no signi>cant 0T abnormality

and the e*ercise test Is negative.