Dual (type IV) left anterior descending artery
Department of Radiology,
Istanbul Medipol University, Istanbul, Turkey
Congenital coronary artery anomalies are uncommon. Dual left
anterior descending coronary artery (LAD) is defined as the
presence of two LADs within the anterior interventricular sulcus
(AIVS), and is classified into four types. Type IV is a rarely
reported subtype and differs from the others, with a long LAD
originating from the right coronary artery (RCA). Dual LAD is a
benign coronary artery anomaly, but should be recognised
especially before interventional procedures. With the increasing
use of multidedector computed tomography (MDCT), it is essential
for radiologists to be aware of this entity and the
cross-sectional findings.
S Afr J Rad 2013;17(4):145-146.
DOI:10.7196/SAJR.959
Dual left anterior descending coronary artery (LAD) is defined
as the presence of two LADs within the anterior interventricular
sulcus (AIVS): a short LAD that courses and terminates high in
the AIVS, and a long LAD that originates from either the LAD
proper or from the right coronary artery (RCA), then enters the
distal AIVS and courses to the apex.1 Type IV can be
differentiated from the other types by the long LAD originating
from the RCA.
Case report
A 52-year-old man was referred to our hospital for chest pain
during exercise. The physical examination and laboratory
findings were unremarkable. The patient underwent coronary CT
angiography (CTA) for evaluation of coronary artery disease. The
CTA showed a short LAD ending high in the AIVS, arising from the
left main coronary artery. The major septal perforators and the
diagonal branches originated from the short LAD. The long LAD
arose from the RCA, after travelling anterior to the pulmonary
artery and right ventricle, re-entering the AIVS at the distal
part (Fig. 1).
Discussion
Coronary artery anomalies associated with their origin, course and distribution are frequently asymptomatic and have been diagnosed during conventional coronary angiography.2 With advances in MDCT technology, it is possible to examine the coronary arteries and heart structures with high spatial and temporal resolution.3 The precise course of the coronary arteries may be easier to appreciate with CTA than with conventional angiography because of the omniplanar capability of CT.
The dual LAD is classified as a
congenital course anomaly of the coronary artery. Dual LAD has
been classified into four types by Spindola-Franko et al. (Fig 2).1 The incidence of dual LAD in
otherwise normal hearts has been reported to range from 0.13%2 to about 1.38%. 1
,
3 This anomaly is seen relatively
often with congenital malformations such as complete
transposition of the great arteries and tetralogy of Fallot.2
Fıg. 2. (A) Type I. The L LAD descends on the left ventricular side of the S LAD then enters the distal AIVS. (B) ype II. The L LAD descends on the right ventricular side of the S LAD and enters the distal AIVS. (C) Type III. The L LAD courses deep within the interventricular septum proximally and appears on the epicardial surface in the distal part of the AIVS. (D) Type IV is characterised by a L LAD originating from the RCA that traverses the right ventricular infundibulum and enters the AIVS. (A = aorta; LAD = left anterior descending coronary artery; L LAD = long LAD; RCA = right coronary artery; S LAD = short LAD; LM = left main coronary artery; s = septal perforator; d = diagonal branches; LCX = left circumflex artery).
When a short or hypoplastic LAD is detected, a differential diagnosis should be sought. There may be a long dominant posterior descending branch of the RCA, terminating in the AIVS beyond the apex; a long parallel diagonal branch; or a dual LAD.4 Short LAD should not be misdiagnosed as total occlusion and a long LAD should not be misdiagnosed as a conus branch.
In conclusion, coronary CTA is a non-invasive imaging
technique using multiplanar reformat and volume rendering images
to show complex anatomy and variations of the coronary arteries.
The radiologist should be familiar with, and looking for, these
conditions during interpretation of coronary CTA imaging.
1. Spindola-Franco H, Grose R, Solomon N. Dual left anterior descending coronary artery: Angiographic description of important variants and surgical implications. Am Heart J 1983;105:445-455. [http://dx.doi.org/10.1016/0002-8703(83)90363-0]
2. Sajja LR, Farooqi A, Shaik MS, Yarlagadda RB, Baruah DK, Pothineni RB. Dual left anterior descending coronary artery: Surgical revascularization in 4 patients. Tex Heart Inst J 2000;27(3):292-296.
3. Erol C, Seker M. The prevalence of coronary artery variations on coronary computed tomography angiography. Acta Radiologica 2012;53:278-284. [http://dx.doi.org/10.1097/RCT.0b013e31822aef59]
4. Yoshikai M, Kamohara K, Fumoto H, Kawasaki H. Dual left anterior descending coronary artery: Report of a case. Surg Today 2004;34(5):453-455. [http://dx.doi.org/10.1007/s00595-003-2733-x]