doi:10.1136/bmj.324.7347.1201 2002;324;1201-1204 BMJ

Richard A Harrigan and Kevin Jones

affecting the right side of the heartABC of clinical electrocardiography: Conditions

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ABC of clinical electrocardiographyConditions affecting the right side of the heartRichard A Harrigan, Kevin Jones

Many diseases of the right side of the heart are associated withelectrocardiographic abnormalities. Electrocardiography isneither a sensitive nor specific tool for diagnosing conditionssuch as right atrial enlargement, right ventricular hypertrophy,or pulmonary hypertension. However, an awareness of theelectrocardiographic abnormalities associated with theseconditions may support the patients clinical assessment andmay prevent the changes on the electrocardiogram from beingwrongly attributed to other conditions, such as ischaemia.

Right atrial enlargementThe forces generated by right atrial depolarisation are directedanteriorly and inferiorly and produce the early part of the Pwave. Right atrial hypertrophy or dilatation is thereforeassociated with tall P waves in the anterior and inferior leads,though the overall duration of the P wave is not usuallyprolonged. A tall P wave (height >2.5 mm) in leads II, III, andaVF is known as the P pulmonale.

The electrocardiographic changes suggesting right atrialenlargement often correlate poorly with the clinical andpathological findings. Right atrial enlargement is associatedwith chronic obstructive pulmonary disease, pulmonaryhypertension, and congenital heart diseasefor example,pulmonary stenosis and tetralogy of Fallot. In practice, mostcases of right atrial enlargement are associated with rightventricular hypertrophy, and this may be reflected in theelectrocardiogram. The electrocardiographic features of rightatrial enlargement without coexisting right ventricularhypertrophy are seen in patients with tricuspid stenosis.P pulmonale may appear transiently in patients with acutepulmonary embolism.

Right ventricular hypertrophyThe forces generated by right ventricular depolarisation aredirected rightwards and anteriorly and are almost completelymasked by the dominant forces of left ventriculardepolarisation. In the presence of right ventricular hypertrophythe forces of depolarisation increase, and if the hypertrophy issevere these forces may dominate on the electrocardiogram.

The electrocardiogram is a relatively insensitive indicator ofthe presence of right ventricular hypertrophy, and in mild casesof right ventricular hypertrophy the trace will be normal.

This article discusses right atrialenlargement, right ventricularhypertrophy, and theelectrocardiographic changes associatedwith chronic obstructive pulmonarydisease, pulmonary embolus, acute rightheart strain, and valvular heart disease

Diagnostic criteria for right ventricular hypertrophy(Provided the QRS duration is less than 0.12 s)x Right axis deviation of + 110 or morex Dominant R wave in lead V1x R wave in lead V1 >7 mm

Supporting criteriax ST segment depression and T wave inversion in leads V1 to V4x Deep S waves in leads V5, V6, I, and aVL

Right ventricular hypertrophy is associated withpulmonary hypertension, mitral stenosis, and, lesscommonly, conditions such as pulmonary stenosis andcongenital heart disease

II

III

aVF

Large P waves in leads II, III, and aVF (P pulmonale)

I

II

III

V1

V2

V3

Right ventricular hypertrophy secondary topulmonary stenosis (note the dominant Rwave in lead V1, presence of right atrialhypertrophy, right axis deviation, and Twave inversion in leads V1 to V3)

Clinical review

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Lead V1 lies closest to the right ventricular myocardiumand is therefore best placed to detect the changes of rightventricular hypertrophy, and a dominant R wave in lead V1 isobserved. The increased rightward forces are reflected in thelimb leads, in the form of right axis deviation. Secondarychanges may be observed in the right precordial chest leads,where ST segment depression and T wave inversion are seen.

A dominant R wave in lead V1 can occur in otherconditions, but the absence of right axis deviation allows theseconditions to be differentiated from right ventricularhypertrophy. Isolated right axis deviation is also associated witha range of conditions.

Chronic obstructive pulmonarydiseaseIn chronic obstructive pulmonary disease, hyperinflation of thelungs leads to depression of the diaphragm, and this isassociated with clockwise rotation of the heart along itslongitudinal axis. This clockwise rotation means that thetransitional zone (defined as the progression of rS to qR in thechest leads) shifts towards the left with persistence of an rSpattern as far as V5 or even V6. This may give rise to apseudoinfarct pattern, with deep S waves in the rightprecordial leads simulating the appearance of the QS wavesand poor R wave progression seen in anterior myocardialinfarction. The amplitude of the QRS complexes may be smallin patients with chronic obstructive pulmonary disease as thehyperinflated lungs are poor electrical conductors.

Cardiac arrhythmias may occur in patients with chronicobstructive pulmonary disease, particularly in association withan acute respiratory tract infection, respiratory failure, orpulmonary embolism. Arrhythmias are sometimes the result ofthe underlying disease process but may also occur as side effectsof the drugs used to treat the disease.

The arrhythmias are mostly supraventricular in origin andinclude atrial extrasystoles, atrial fibrillation or flutter, andmultifocal atrial tachycardia. Ventricular extrasystoles andventricular tachycardia may also occur.

Conditions associated with tall R wave in lead V1x Right ventricular hypertrophyx Posterior myocardial infarctionx Type A WolffParkinsonWhite syndromex Right bundle branch block

A tall R wave in lead V1 is normal in children and young adults

Conditions associated with right axis deviationx Right ventricular hypertrophyx Left posterior hemiblockx Lateral myocardial infarctionx Acute right heart strain

Right axis deviation is normal in infants and children

About three quarters of patients withchronic obstructive pulmonary diseasehave electrocardiographic abnormalities.P pulmonale is often but not invariablypresent and may occur with or withoutclinical evidence of cor pulmonale

In chronic obstructive pulmonary disease theelectrocardiographic signs of right ventricularhypertrophy may be present, indicating the presence ofcor pulmonale

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6Chronic obstructive pulmonary disease(note the P pulmonale, low amplitude QRScomplexes, and poor R wave progression)

Multifocal atrialtachycardia

Clinical review

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Acute pulmonary embolismThe electrocardiographic features of acute pulmonaryembolism depend on the size of the embolus and itshaemodynamic effects and on the underlying cardiopulmonaryreserve of the patient. The timing and frequency of theelectrocardiographic recording is also important as changesmay be transient. Patients who present with a small pulmonaryembolus are likely to have a normal electrocardiogram or atrace showing only sinus tachycardia.

If the embolus is large and associated with pulmonaryartery obstruction, acute right ventricular dilatation may occur.This may produce an S wave in lead I and a Q wave in lead III.T wave inversion in lead III may also be present, producing thewell known S1, Q3, T3 pattern.

Right ventricular dilatation may lead to right sidedconduction delays, which manifest as incomplete orcomplete right bundle branch block. There may be somerightward shift of the frontal plane QRS axis.

Right atrial dilatation may lead to prominent P waves inthe inferior leads. Atrial arrhythmias including flutter andfibrillation are common, and T wave inversion in the rightprecordial leads may also occur

The S1, Q3, T3 pattern is seen in about12% of patients with a massive pulmonaryembolus

I

III

Sinus tachycardia and S1,Q3, T3 pattern in patientwith pulmonary embolus

II

III

aVRI

aVL

aVF

V1

V2

V3

V4

V5

V6

Preoperative electrocardiogram in otherwise healthy 38 year old man

II

III

aVRI

aVL

aVF

V1

V2

V3

V4

V5

V6 Acute pulmonaryembolism: 10 dayspostoperatively thesame patient developedacute dyspnoea andhypotension (note theT wave inversion in theright precordial leadsand lead III)

Clinical review

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Acute right heart strainWhen the electrocardiogram shows features of right ventricularhypertrophy accompanied by ST segment depression andT wave inversion, a ventricular strain pattern is said to exist.Ventricular strain is seen mainly in leads V1 and V2. Themechanism is unclear. A strain pattern is sometimes seen inacute massive pulmonary embolism but is also seen in patientswith right ventricular hypertrophy in the absence of anydetectable stress on the ventricle. Both pneumothorax andmassive pleural effusion with acute right ventricular dilatationmay also produce a strain pattern.

Right sided valvular problemsTricuspid stenosisTricuspid stenosis is a rare disorder and is usually associatedwith rheumatic heart disease. It appears in theelectrocardiogram as P pulmonale. It generally occurs inassociation with mitral valve disease, and therefore theelectrocardiogram often shows evidence of biatrialenlargement, indicated by a large biphasic P wave in lead V1with an initial positive deflection followed by a terminalnegative deflection.

Tricuspid regurgitationThe electrocardiogram is an unhelpful tool for diagnosingtricuspid regurgitation and generally shows the features of theunderlying cardiac disease. The electrocardiographicmanifestations of tricuspid regurgitation are nonspecific andinclude incomplete right bundle branch block and atrialfibrillation.

Pulmonary stenosisPulmonary stenosis leads to pressure overload in the rightatrium and ventricle. The electrocardiogram may be completelynormal in the presence of mild pulmonary stenosis. Moresevere lesions are associated with electrocardiographic featuresof right atrial and ventricular hypertrophy, with tall P waves,marked right axis deviation, and a tall R wave in lead V1.

Kevin Jones is consultant chest physician at Bolton Royal Hospital.Richard A Harrigan is associate professor of emergency medicine atTemple University School of Medicine and associate research director,division of emergency medicine, Temple University Hospital,Philadelphia, PA, USA.

BMJ 2002;324:12014

Electrocardiographic abnormalities found in acutepulmonary embolismx Sinus tachycardiax Atrial flutter or fibrillationx S1, Q3, T3 patternx Right bundle branch block (incomplete or complete)x T wave inversion in the right precordial leadsx P pulmonalex Right axis deviation

The ABC of clinical electrocardiography is edited by Francis Morris,consultant in emergency medicine at the Northern General Hospital,Sheffield; June Edhouse, consultant in emergency medicine, SteppingHill Hospital, Stockport; William J Brady, associate professor,programme director, and vice chair, department of emergencymedicine, University of Virginia, Charlottesville, VA, USA; and JohnCamm, professor of clinical cardiology, St Georges Hospital MedicalSchool, London. The series will be published as a book in thesummer.

II

III

aVRI

aVL

aVF

V1

V2

V3

V4

V5

V6

S1, Q3, T3 pattern and right bundle branch block in patient withpulmonary embolus

V1

V2

V3

V4

V5

V6

Example of right heart strain: right ventricular hypertrophy withwidespread T wave inversion in chest leads

V1II

Biatrial abnormality

Clinical review

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