What does "complex" mean?

Complex means that treating the narrowing is technically more difficult. For example, the narrowing may be at a point where the artery divides, it may be heavily calcified or long, it may be in more than one artery, or it may have come back inside an old stent. In these situations the procedure may need more preparation, additional devices and more time.

Can a calcified artery be opened?

In suitable patients, yes; however, in a heavily calcified artery a balloon on its own may not be enough. In that case the calcium may be worn away with rotational atherectomy or broken up with intravascular lithotripsy; the aim is to prepare the artery so that the stent can open well. For some patients bypass surgery may be more appropriate. Your doctor decides which approach suits you, based on the anatomy of your arteries.

Why is imaging from inside the artery used?

An angiogram shows only a silhouette of the inside of the artery. Imaging from inside the artery (IVUS or OCT) looks at the artery from within and shows its size, the amount of calcium and the structure of the plaque in more detail. This information helps in choosing the right stent size and in checking that the stent has opened well. Current guidelines recommend that stenting of complex narrowings, such as bifurcations and long narrowings, is guided by imaging from inside the artery.

In case of sudden chest pain, shortness of breath or fainting, call 112.

Complex coronary interventions

Narrowings at a point where an artery divides, heavily calcified or long narrowings, and narrowings that return inside a stent can be treated with balloons and stents, using additional techniques and imaging from inside the artery. The aim is to reduce symptoms such as chest pain and breathlessness.

What is it?

Because of their structure, some coronary narrowings are harder to treat with a balloon and stent than usual; these are called complex narrowings. The narrowing may be at a point where the artery divides in two (a bifurcation). The artery wall may be heavily calcified, or the narrowing may stretch over a long segment. There may be narrowings in more than one artery (multivessel disease), or an artery may narrow again inside a previously placed stent. In a heavily calcified artery, a balloon on its own may not widen the narrowing enough, and the stent may not expand fully. In this case the calcium can be worn away with a small device that has a tip spinning at high speed (rotational atherectomy), or broken up with sound (pressure) waves sent from a special balloon inside the artery (intravascular lithotripsy). Which method is used depends on where the calcium is and how widespread it is; these methods are not needed in every patient. If an artery narrows again inside a previously placed stent, the cause is investigated first, and imaging from inside the artery helps with this. If needed, the narrowed segment is first prepared with a high-pressure balloon or with methods that wear away or break up calcium. For renewed narrowing inside a drug-eluting stent, the current guideline prefers placing a new drug-eluting stent inside the old one; in some patients a balloon coated with medicine (drug-coated balloon) may be used. When there are narrowings in more than one artery, the choice between stenting and bypass surgery is made by the heart team, meaning a cardiologist and a heart surgeon assessing the case together. This decision takes into account the anatomy of the arteries, how widespread the narrowings are, other conditions such as diabetes, and the patient's preference. Arteries that have been completely blocked for a long time (chronic total occlusion, CTO) are covered on a separate page of this site. Prof. Dr. Barış Kılıçaslan performs complex coronary interventions in his clinical practice.

Who is it for?

Patients whose angiogram shows a narrowing that is harder to treat, such as a bifurcation, heavy calcification, a long narrowing or renewed narrowing inside a stent
Patients whose symptoms, such as chest pain or breathlessness, continue despite medication, or whose tests show that the heart muscle is not getting enough blood (ischaemia)
The decision is made by looking together at your symptoms, test results, the anatomy of your arteries and your general health. For some patients bypass surgery or medication may be more appropriate

Before the procedure

Your previous angiogram images are studied in detail to plan the procedure. Whether a narrowing really limits blood flow can be measured with a thin pressure wire advanced into the artery (measurements such as FFR). If there are narrowings in more than one artery, this measurement can help decide which of them should be treated. The size of the artery, the amount of calcium and the structure of the plaque can be examined in detail with imaging from inside the artery: intravascular ultrasound (IVUS) or optical coherence tomography (OCT). These measurements are often made during the angiogram, before treatment begins. Before the procedure you will have blood tests and your kidney function is checked, because the dye used in the procedure is cleared by the kidneys. Tell your doctor beforehand if you have ever had an allergy to contrast dye, or if you have kidney disease or diabetes. Your medications, especially blood thinners and diabetes medicines, are reviewed with your doctor; do not stop any medication on your own.

How is it done?

Access site: A thin sheath is placed in the artery at the wrist or groin. Depending on the devices to be used, the groin artery or two access sites may be needed.
Preparing the artery: A fine wire is passed across the narrowing and the artery is widened with a balloon. In heavily calcified arteries, if the balloon does not open the narrowing well enough, the calcium may be worn away with rotational atherectomy or broken up with intravascular lithotripsy.
Bifurcation technique: If the narrowing is at a point where the artery divides, a wire may also be placed in the side branch to protect it. Usually a stent is placed in the main artery first; the side branch is opened with a balloon if needed, and a stent is placed in the side branch only when necessary.
Stent and imaging check: A drug-eluting stent is placed at the narrowing. In complex narrowings such as bifurcations and long narrowings, imaging from inside the artery is used to choose the stent size and to check that the stent is fully expanded and sits well against the artery wall. If the stent is not fully expanded, it is widened further with a balloon.
Check and closure: The result is checked with imaging. The catheters are removed; at the wrist the access site is compressed with a pressure band, and at the groin it is closed or compressed.

Recovery

After the procedure you stay under observation for a while. If a stent was placed, it is very important to take the anti-clotting medicines without missing doses for as long as your doctor recommends. Do not stop them without talking to your cardiologist, even before another treatment or a dental procedure. A stent opens the narrowing, but it does not remove the underlying artery disease. Regular check-ups, keeping cholesterol, blood pressure and blood sugar under control, stopping smoking, regular activity and a healthy diet help slow the disease down. Cardiac rehabilitation programmes can also help during this time.

Risks

Like every interventional procedure, complex coronary interventions have risks. These include bleeding or bruising at the access site, an allergic reaction to the contrast dye, a decline in kidney function, injury to the artery and heart rhythm disturbances. Less commonly, a heart attack, stroke, a clot forming in the stent or a situation needing emergency surgery can occur. Because the procedure can take longer, more dye and X-ray may be needed, so the effects on the kidneys and skin are given extra attention. In bifurcation narrowings, the side branch can narrow or close. Rarely, especially in calcified arteries, the heart artery can tear and blood can collect in the sac around the heart; this may need emergency treatment. Your possible benefits and risks are explained in detail by your doctor, according to your personal situation, at the consultation before the procedure.

Frequently asked questions

What does "complex" mean? Complex means that treating the narrowing is technically more difficult. For example, the narrowing may be at a point where the artery divides, it may be heavily calcified or long, it may be in more than one artery, or it may have come back inside an old stent. In these situations the procedure may need more preparation, additional devices and more time.
Can a calcified artery be opened? In suitable patients, yes; however, in a heavily calcified artery a balloon on its own may not be enough. In that case the calcium may be worn away with rotational atherectomy or broken up with intravascular lithotripsy; the aim is to prepare the artery so that the stent can open well. For some patients bypass surgery may be more appropriate. Your doctor decides which approach suits you, based on the anatomy of your arteries.
Why is imaging from inside the artery used? An angiogram shows only a silhouette of the inside of the artery. Imaging from inside the artery (IVUS or OCT) looks at the artery from within and shows its size, the amount of calcium and the structure of the plaque in more detail. This information helps in choosing the right stent size and in checking that the stent has opened well. Current guidelines recommend that stenting of complex narrowings, such as bifurcations and long narrowings, is guided by imaging from inside the artery.

Medical content reviewed and approved by Prof. Dr. Barış Kılıçaslan. Last updated: 4 October 2026. Editor: Baran Zeydan (info@clinixcrm.app).