Cardiology - Nomenclature

AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020


Several areas of cardiology use simple letter terms and alphanumeric terms that do not need to be expanded at first mention.

14.3.1 Electrocardiographic Terms.

International standardization of electrocardiographic nomenclature dates back to the mid-20th century.1,2,3,4 The preferred abbreviation for electrocardiogram and electrocardiographic is ECG, not EKG. In the following examples of ECG terms, note the use of capitals, lowercase letters, subscripts, and hyphens. Leads.

Leads (recording electrodes) are designated in Table 14.3-1.

Table 14.3-1. Types and Names of Electrocardiographic Leads

Types of leads


standard (bipolar) leads


augmented limb leads/unipolar extremity leads (a, augmented; V, voltage; R, right arm; L, left arm; F, foot)

aVR, aVL, aVF

inverted aVR lead


(unipolar) precordial (chest) leads

V1, V2, V3, V4, V5, V6, V7, V8, V9 (eg, leads V3 through V6 [not V3-V6 or V3-6])

right precordial leads

V1R, V2R, V3R, V4R, V5R, V6R

modified chest lead using V1

MCL1 Deflections.

The main deflections of the ECG (Figure 14.3-1) are named in alphabetical sequence (P, Q, R, S, T, U), a usage that dates back to the inventor, Willem Einthoven.2 Other deflections use initial letters of the entity being described.

Capital letters are used to describe generic ECG deflections.

Improper paper speed during ECG recording will spuriously alter the QRS configuration [not qrs configuration].

In reference to an individual ECG tracing, or in descriptions of some specific ECG patterns, capital letters may indicate larger waves and lowercase letters smaller waves; in practice, this most often applies to the Q, R, and S waves.

Pathologic Q waves occur in myocardial infarction.

The q wave in aVF and the Rr′ pattern in lead V3 in this patient’s ECG were considered normal findings.

An rSR′ complex in the anterior chest leads and qRs in the left chest leads may indicate right bundle-branch block.

As a guide, hyphens usually do not link deflection terms in the same PQRSTU complex (eg, QT) but link deflections in different waves (eg, R-R), with the exception of ST-T. The following are examples of terms descriptive of deflections and patterns in ECG tracings:

delta wave (preferred over ∆ wave; a slurred upstroke in the QRS complex that is associated with a short PR interval)

F wave (atrial flutter wave)

f wave (atrial fibrillation wave)

J point, J junction (junction of QRS complex and ST segment)

J-ST axis, vector

LQTS (long QT syndrome)

NSTEMI (non—ST-segment elevation myocardial infarction)

NSTE ACS (non—ST-segment elevation acute coronary syndrome)

P wave, axis, etc

PR interval, segment, etc (not P-R)

Figure 14.3-1. Electrographic Deflections (Schematic)


Q wave, q wave

qR complex

QR-type complex

QRS complex (usually a combination of Q, R, and S waves), QRS configurations (if the QRS complex lacks an R wave, it is called a QS complex; if the QRS complex lacks a Q wave, it is called an RS complex)

QRS-T complex

QS wave, qs wave

QT interval, prolongation, etc (not Q-T)

QTc (corrected QT interval)

R wave, r wave, R′ wave, r′ wave


R-R interval

rS, RS, Rs complex, configuration, etc

R/S (ratio)

rSR′ pattern

S wave, s wave

S′ wave, s′ wave

ST segment, depression, axis, etc (not S-T)

ST-segment abnormality

ST-T segment, elevation, changes, axis, etc (not S-T-T)

STEMI (ST-segment elevation myocardial infarction)

T wave, axis, etc

Ta wave (atrial repolarization)

TQ segment

U wave

When terms such as the foregoing are used as modifiers, use a hyphen before the modifying noun (see 8.3, Hyphens and Dashes).

P-wave duration

Q-wave irregularity

non—Q-wave myocardial infarction

ST-segment depression (not S-T)

The following symbols are used in connection with ECGs obtained from patients with pacemakers:


atrial stimulus


ventricular stimulus


interval from atrial stimulus to succeeding ventricular stimulus


interval from atrial stimulus to conducted spontaneous ventricular depolarization


interval from spontaneous atrial depolarization to succeeding “atrial-synchronous” ventricular stimulus

Lead and tracing terms may be combined to describe pattern and location together.


R wave in lead I


R wave in aVL


S wave in lead III


R wave in V3

S1Q3T3 pattern

prominence of S wave in lead I, Q wave in lead III, and T-wave inversion in lead III

SV1 + RV5

sum of voltages of S wave in V1 and R wave in V5

The P axis, QRS axis, ST axis, and T axis are specified with a plus or minus sign followed by the number of degrees in arabic numerals (eg, +60°, −30°).

14.3.2 Electrograms.

Electrogram (EGM) terms pertain to invasive electrophysiologic recording of cardiac impulse conduction. Expand these terms at first mention.

AH interval

atrial-His interval


His potential

HV interval

His-ventricular interval

14.3.3 Heart Sounds.

The 4 heart sounds and 4 components are commonly abbreviated in discussions of cardiac auscultatory findings; numerical subscripts are used.

S1 first heart sound

M1 mitral valve component

T1 tricuspid valve component

S2 second heart sound

A2 aortic valve component

P2 pulmonic valve component

S3 third heart sound

✵ The presence of an audible S3 was consistent with the patient’s ventricular aneurysm.

S4 fourth heart sound

✵ An audible S4 may be due to a variety of cardiac and systemic conditions.

Sound names may be written out in full when discussed generically.

Third heart sounds are suggestive of congestive heart failure, but an S3 gallop may be a normal finding in children and young adults.


The S3 is suggestive of congestive heart failure, but an S3 gallop may be a normal finding in children and young adults.

For plurals, follow the term with “sounds” or another noun.

S3 sounds [not S3s] may be normal or pathologic.

S3 gallops may be a normal finding in children and young adults.

14.3.4 Murmurs.

Murmurs are graded from soft (lower grade) to loud (higher grade). Murmur grades are written in arabic numerals. Systolic murmurs may be graded from 1 to 6 (see Freeman and Levine5) and diastolic from 1 to 4. Murmurs may also be presented by means of a virgule construction to indicate highest grade, as in the following examples:

grade 2 systolic murmur

grade 1 diastolic murmur

grade 4/6 systolic murmur

grade 2/4 diastolic murmur

The patient had a grade 3 systolic murmur radiating to the axilla consistent with the diagnosis of mitral valve regurgitation.

14.3.5 Jugular Venous Pulse.

The jugular venous pulse (JVP) contours are expressed with italic single letters and roman words:

a wave (atrial)

x descent

z point

c wave

x′ descent

v wave (ventricular)

y descent (or y trough)

h wave

Examples are as follows:

prominent a wave

giant a wave

steep x descent

increased v wave

abrupt y descent

14.3.6 Echocardiography.

The names of major echocardiographic methods are listed below. Expand any abbreviations at first mention.

2-dimensional echocardiography (2DE)

3-dimensional echocardiography (3DE)

4-dimensional echocardiography (4DE)

adenosine stress echocardiography

cardiac catheter echocardiography

color Doppler echocardiography

color flow Doppler echocardiography

continuous-wave Doppler echocardiography (CW Doppler)

contrast echocardiography

dipyridamole stress echocardiography

dobutamine stress echocardiography

Doppler echocardiography

Doppler flow imaging

exercise echocardiography

intravascular ultrasonography (IVUS)

pharmacologic stress echocardiography

pulsed Doppler echocardiography

spectral Doppler echocardiography

standard transthoracic echocardiography6 (a combination of 2-dimensional echocardiography, M-mode [motion mode], and Doppler flow imaging)

echocardiography, M-mode [motion mode], and Doppler flow imaging

stress echocardiography

transesophageal echocardiography (TEE)

The following commonly used echocardiographic indexes should also be expanded at first mention:


aortic valve area


ejection fraction


E point septal separation


fractional area change


fractional shortening


interventricular septal thickness


left ventricular internal dimension


mitral valve area


pressure half-time


posterior wall thickness


right ventricular internal dimension


systolic anterior motion of the mitral valve

d or ed

end diastole

s or es

end systole

Terms are combined as in the following examples:


interventricular septal thickness at diastole


interventricular septal thickness at systole


left ventricular internal diameter at diastole


left ventricular internal diameter at the end of diastole


left ventricular internal diameter at the end of systole


left ventricular internal dimension at systole


left ventricular posterior wall dimension at diastole


left ventricular posterior wall dimension at systole


right ventricular internal dimension at diastole

Ejection fraction (EF) is expressed as a percentage (eg, 60%) (see 18.0, Numbers and Percentages).

14.3.7 Pacemaker Codes.

The capabilities and operation of cardiac pacemakers are described by 3- to 5-letter codes.7,8

DDIR pacing

VVI pacemaker

The code system for antibradycardia pacemakers endorsed by the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Group (BPEG) is known as the NASPE/BPEG Generic Code or NBG Code. Although the code need not be expanded when mentioned in passing, it is good practice to describe pacing modes in prose at first mention, for example, “dual-chamber, adaptive-rate (DDDR) pacing.” The NBG Code was revised in 2001 to apply to antibradycardia, adaptive rate, and multisite pacing.9,10

In Table 14.3-2, positions I through V refer to the first through fifth letters of the NBG Code. The character for “none” is the letter O, not the numeral 0. In practice, the first 3 positions are always given; the fourth and fifth are added when necessary to provide additional information.

Table 14.3-2. Revised North American Society of Pacing and Electrophysiology (NASPE)/British Pacing and Electrophysiology Group (BPEG) Generic Code for Antibradycardia Pacinga








Chamber(s) paced

Chamber(s) sensed

Response to sensing

Rate modulation

Multisite pacing

O = none

O = none

O = none

O = none

O = none

A = atrium

A = atrium

T = triggered

R = rate modulation

A = atrium

V = ventricle

V = ventricle

I = inhibited

V = ventricle

D = dual (A+V)

D = dual (A + V)

D = dual (T + I)

D = dual (A + V)

Manufacturers’ designation only

S = single (A or V)

S = single (A or V)

a Reproduced with permission from Bernstein et al.9

14.3.8 Implanted Cardioverter-Defibrillators.

A similar code, known as the NASPE/BPEG Defibrillator Code or NBD Code,11 exists for implanted cardioverter/defibrillators (ICDs), as defined in Table 14.3-3.

Table 14.3-3. Revised NASPE/BPEG Generic Code for Defibrillatorsa

Position I (shock chamber)

Position II (antitachycardia pacing chamber)

Position III (tachycardia detection)

Position IV (antibradycardia pacing chamber)

O = none

O = none

E = electrocardiogram

O = none

A = atrium

A = atrium

H = hemodynamic

A = atrium

V = ventricle

V = ventricle

V = ventricle

D = dual (A + V)

D = dual (A + V)

D = dual (A + V)

a Reproduced with permission from Bernstein et al.11

Examples are as follows:

DDH defibrillator

VOEO defibrillator

There is also a Short Form of the NBD Code intended only for use in conversation:


ICD with antibradycardia pacing as well as shock


ICD with antitachycardia pacing as well as shock and antibradycardia pacing


ICD with shock capability only

The foregoing terms can each represent a variety of devices; for instance, ICD-S could indicate VO, VOE, VOEO, DOH, or DOHV. The same devices may also be represented by more than 1 term; for instance, ICD-B may also represent VO and VOE, among other devices. Therefore, only the Long Form is used in writing. As in the case of the NBG Code, at first mention of an ICD it is good practice to include a prose description and the NBD Code designation.

For maximum conciseness and completeness in ICD labeling and record keeping, the first 3 positions of the NBD Code are given, followed after a hyphen by the first 4 positions of the NBG Code. Thus, VAE-DDDR refers to an ICD providing ventricular shock, atrial antitachycardia pacing, EGM sensing for tachycardia detection, and dual-chamber, adaptive-rate antibradycardia pacing.

14.3.9 Pacemaker-Lead Code.

The NASPE/BPEG Pacemaker-Lead Code (NBL Code)12 is detailed in Table 14.3-4.

Table 14.3-4. Revised North American Society of Pacing and Electrophysiology (NASPE)/British Pacing and Electrophysiology Group (BPEG) Pacemaker-Lead Codea

I (Electrode configuration)

II (Fixation mechanism)

III (Insulation material)

IV (Drug elution)

U = unipolar

A = active

P = polyurethane

S = steroid

B = bipolar

P = passive

S = silicone rubber

N = nonsteroid

M = multipolar

O = none

D = dual (P + S)

O = none

a Reproduced with permission from Bernstein and Parsonnet.12

Typically, all 4 positions are mentioned (eg, UPSO, BAPS).

Cardiac resynchronization therapy (CRT) devices, also known as biventricular devices, have additional functions and can be combined with implantable cardioverter-defibrillators, such as ICD/CRT, or can be stand-alone CRT devices.

14.3.10 Heart Disease Classifications and Scoring Systems.

Several classifications and scoring systems pertinent to heart disease are in use (Table 14.3-5).

Table 14.3-5. Heart Disease Classifications


Applies to




unstable angina


Braunwald class I Braunwald class IIIB

Canadian Cardiovascular Society (CCS)14,15

exertional angina


CCS class II

CHA2DS2-VASc score16

atrial fibrillation stroke risk

Score of 0, low risk; ≥2, high risk; maximum score, 10

CHA2 DS2-VASc Score ≥2


cardiac function after myocardial infarction


Forrester class I

Global Registry of Acute Coronary Events (GRACE)20,21

acute coronary events

ST-segment—elevation myocardial infarction; non—ST-segment—elevation myocardial infarction; unstable angina

GRACE variables include ST-segment elevation and patient age


cardiac status after myocardial infarction


Killip class I heart failure

New York Heart Association (NYHA)24

cardiac disease and functional capacity


NYHA class I

Thrombolysis in Myocardial Infarction (TIMI)25 (eg, TIMI Risk Score, TIMI Grade Flow)

acute coronary syndrome

Score of 0-1, lowest risk; 6-7, highest risk

TIMI score 0-1

The classes are assessed in various ways, for instance, by physical examination (Killip), hemodynamic measurement (Forrester), and patient history (NYHA). The detailed meanings of each class are beyond the scope of this book, but several style points may be noted:

■Severity increases from lower to higher numbers and letters.

■There is no automatic correspondence among classes (eg, Killip class I is not equivalent to NYHA class I).

■The numerals for the classes, unlike those for the scores, are designators and are not quantitative or semiquantitative. Therefore, roman numerals are appropriate for those, whereas arabic numerals are used for the scores. The scores are a sum of points for various components.


Forrester class >2


Forrester class above II class greater than Forrester II Forrester classes III and IV

■Authors should describe their classification criteria, for instance:

Killip class on admission was determined as the following: patients whose disease was considered class I were free of rales and a third heart sound; patients whose disease was class II had rales up to 50% of each lung field regardless of the presence of the third heart sound. . . (adapted from Neskovic et al26).

We suggest that cases of unstable angina class IIIB now be subdivided into troponin-positive and troponin-negative subgroups. . . (adapted from Hamm and Braunwald27[p120]).

14.3.11 Coronary Artery Angiographic Classifications.

Guidelines are available for nomenclature of coronary artery segments,28 used in coronary artery catheterization and thrombolysis in myocardial infarction flow (TIMI flow).

The TIMI flow is expressed as grade 0, grade 1, grade 2, or grade 3, from lowest flow (or severest lesion) to highest flow.27

14.3.12 Cellular and Molecular Cardiology. Cardiac Muscle.

These descriptive terms do not require expansion:

A band

actin-myosin overlap

H band

Hensen (discoverer)

M line


T tubules

tubulus transversus

Z line

Zückung (German: “contraction”)

Expand these terms at first mention:


troponin C (binds calcium)


troponin I (inhibits actin-myosin interactions)


troponin T (binds to tropomyosin)


troponin C, cardiac form


troponin I, cardiac form


troponin T, cardiac form


high-sensitivity troponin Lipoproteins and Related Terms.

Expand the following lipoproteins and related terms at first mention:

acyl CoA

acyl coenzyme A


high-density lipoprotein


HDL variant


HDL subfraction 2


HDL subfraction 3


HDL cholesterol


HDL receptor


3-hydroxy-3-methylglutaryl coenzyme A


intermediate-density lipoprotein


IDL cholesterol


IDL receptor


low-density lipoprotein


LDL cholesterol


LDL particle number


LDL receptor


lipoprotein a


lipoprotein lipase gene (see 14.6.2, Human Gene Nomenclature)


mutation in LPL at codon 188 (see 14.6.1, Nucleic Acids and Amino Acids)


substitution in LPL of serine at asparagine residue 29


lipoprotein X


LDL-R—related protein


LDL-R—related protein 2


very high-density lipoprotein


VLDL cholesterol


VLDL receptor

Expand apo as apolipoprotein at first mention of terms such as the following:

apo AI

apo B48

apo CI

apo D

apo E

apo J

apo AII

apo B100

apo CII

apo E2

apo AIII

apo CIII

apo E3

apo AIV


apo AIMilano

apo AIArg173Cys (substitution of cysteine at arginine 173 residue) (see 14.6.1, Nucleic Acids and Amino Acids) Miscellaneous Cellular and Biochemical Terms.

If an expansion is given, use at first mention. Otherwise, terms may be used without expansion.


endothelial leukocyte adhesion molecule involved in atherosclerosis


B-type natriuretic peptide


creatine kinase, myocardial (largely considered obsolete as a test for myocardial infarction; replaced by troponin [Tn])


nitric oxide synthase


neuronal NOS (named in order of discovery, also nNOS


also iNOS (inducible NOS)


also eNOS, ecNOS (endothelial constitutive isoform of NOS)

P cell

nodal cells of the sinus node


tissue plasminogen activator

Principal Author: Cheryl Iverson, MA


Thanks to the following for reviewing and providing comments: Philip Greenland, MD, JAMA, and Northwestern University, Chicago, Illinois; Eric D. Peterson, MD, MPH, JAMA, and Duke University School of Medicine, Durham, North Carolina; Rita F. Redberg, MD, MSc, JAMA Internal Medicine, and Women’s Cardiovascular Services, University of California, San Francisco; Rochelle C. Lodder, formerly with JAMA Network; and Philip Sefton, MS, ELS, JAMA. Thanks also to David Song, JAMA Network, for obtaining permissions.


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