Posterior descending artery (PDA) !
The posterior descending artery runs in the groove on the underside of the heart; it feeds the lower wall and the back of the septum.
Official name: Inferior interventricular artery
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What it is
Runs in the posterior interventricular groove from the crux of the heart toward the apex, beside the middle cardiac vein. The artery that gives off the PDA decides 'dominance': in about 7 of 10 people it comes from the right coronary (right dominance), otherwise from the circumflex (left dominance) or from both (codominance).
What it does
Feeds the inferior wall of both ventricles and the back third of the interventricular septum through its septal branches. Blocked in an inferior heart attack (ECG changes in II, III and aVF); when the right coronary is the culprit, slow heart rhythms and AV block are common because it usually also feeds the AV node.
Key facts
- Origin
- Right coronary artery in right-dominant hearts (most people); circumflex in left-dominant hearts; both in co-dominant hearts
- Branches
- Septal perforators to the posterior third of the interventricular septum; branches to the inferior walls of both ventricles
- Supplies
- Inferior LV and RV walls and posterior third of the septum; its occlusion is part of an inferior myocardial infarction
Relations
- Course
- Leaves the dominant artery at or near the crux and runs in the posterior interventricular groove toward the apex, where it may meet the end of the LAD
- Below
- Diaphragmatic surface of the heart, resting on the central tendon of the diaphragm
- Deep
- Posterior (inferior) part of the interventricular septum, which its septal branches enter
How to find it
Seen when the heart is lifted to show its diaphragmatic surface: it runs down the posterior interventricular groove toward the apex, beside the middle cardiac vein, often under epicardial fat. This is where a bypass graft to the inferior wall is sewn.
On imaging
On coronary angiography it is seen in the left anterior oblique cranial and right anterior oblique views of a right coronary injection, or filling from the left injection in left dominance. CT coronary angiography establishes dominance before surgery or a catheter procedure.
Common problems
- Coronary artery disease: fatty plaque narrows them, causing chest pain on exertion (angina).
- Heart attack: a plaque breaks open and a clot suddenly blocks the artery.
How it is diagnosed
ECG and troponin for a heart attack; stress test, CT coronary angiography or a catheter angiogram to see narrowings.
Treatment
- Medicines (aspirin, statins, blood-pressure control) and stopping smoking.
- Angioplasty and stent through a catheter.
- Bypass surgery (CABG) for several or complex blockages.
Clinical notes
- Papillary muscle rupture a few days after an inferior MI presents with sudden pulmonary edema and a new murmur
- A bypass graft to the posterior descending artery revascularizes the inferior wall
Anatomical variants
- When the LAD wraps around the apex, the posterior descending artery is short and the LAD supplies the lower part of the inferior septum
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
What determines coronary dominance?
The artery that gives off the posterior descending artery: the right coronary artery in about 7 of 10 people (right dominance), otherwise the circumflex or both.
Which papillary muscle does the posterior descending artery usually supply alone, and what is the clinical consequence?
The posteromedial papillary muscle; an inferior myocardial infarction can rupture it, causing sudden severe mitral regurgitation.
Which part of the interventricular septum does the posterior descending artery supply?
The posterior third, through its septal perforators.
In which ECG leads does an inferior infarction from posterior descending artery occlusion appear?
Leads II, III and aVF.
Why are slow rhythms and AV block common when the right coronary artery is the culprit in inferior infarction?
The right coronary artery usually also feeds the atrioventricular (AV) node.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- arteria interventricularis inferior TA2 4138
- Official Spanish (DeCS)
- Rama interventricular posterior de la arteria coronaria derecha
- English (TA2)
- Inferior interventricular artery
- Also called
- posterior descending artery · PDA · posterior interventricular artery · inferior intervenricular branch of right coronary artery · posterior interventricular branch of right coronary artery · ramus interventricularis arteriae coronariae dextrae · ramus descendens posterior
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Thorax, Heart Left Anterior Descending (LAD) Artery; Anatomy, Thorax, Heart; Anatomy, Thorax, Sinoatrial Nodal Artery.
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Representative model, for educational purposes only.