Chronic Total Occlusion.

Training of Acrostak

number the figures (Fig.1)

[pic 2]

This is for private use only^[1].

Table of contents

Table of contents        2

I.        What is a CTO        4

A.        Types of CTO        5

True total occlusion / Functional total occlusion        5

Old / young CTO        5

B.        Formation of a CTO        5

II.        Who can have a CTO        7

III.        How to treat a CTO        7

A.        Who can do a CTO        7

B.        Factors for the success of a CTO recanalization        7

C.        Steps for CTO recanalization        9

D.        Which products to use?        11

The guiding catheter        11

The guidewire        13

E.        Stent implantation        15

F.        Dual antiplatelet therapy        15

IV.        Techniques of revascularization        16

A.        Antegrade approach        16

The parallel wire technique        17

The see-saw technique        18

The STAR technique        18

The Microchannel technique        18

B.        Retrograde approach        19

The kissing wire technique        21

The landmark retrograde technique        21

The Knuckle technique        22

The CART (Controlled Antegrade and Retrograde subintimal Tracking) technique        22

The reverse CART technique        22

V.        Benefits of a CTO revascularization        23

A.        Treatment of CTOs        23

B.        Benefits of the treatment        24

VI.        To go further        26

VII.        FAQ        26

A.        General objections        26

B.        Acrostak product objection        28

Across CTO ST        28

Across HP        29

1. What is a CTO

CTO stands for Chronic Total Occlusion and it refers to the arteries.

Chronic total occlusion means a total or almost total occlusion of the artery by atherosclerosis, a progressive disease characterized by the accumulation of lipids and fibrous elements in the large arteries.

It is usually defined by more than 3-month-old obstruction of a native^[2] coronary artery. The picture below shows a Chronic Total Occlusion seen on an angiography.

[pic 3]

Image: Incathlab

CTOs are often considered as the most complicated lesion because of the inability to cross or dilate it and to its high incidence of restenosis and reocclusion after the treatment.” It is hard to enter in these lesions because the concentration of fibrous tissue is higher at the proximal and distal part of the lesion. This blocks the entry or progression of the wire, and can deflect it in the artery’s wall.

Without any blood passing through the artery, the occluded artery can’t be seen during the angiography –unless using dual injection views -. It is then difficult for the operator to visualize where the artery goes.

1. Types of CTO

We can differentiate CTO depending on their nature:

True total occlusion / Functional total occlusion

True total occlusion is when the artery is totally blocked and no blood flow pass.

Functional total occlusion is an occlusion with still blood flow penetrating but considered as minimal.

Or we can differentiate them depending on their age:

Old / young CTO

The composition of a CTO depends on how long ago it was formed.

Occlusion formed more than a year are considered old occlusions. They have a high concentration of hard material like fibrocalcific (fibrous tissue + calcification) material, which makes it hard to cross.

Occlusion formed less than year are softer and easier to cross and are considered young occlusions.

1. Formation of a CTO

There are two types of formation of CTO:

1. Development of acute occlusion due to a plaque rupture with a large accumulation of old thrombus.

[pic 4]

Image: http://whatcardiologyis.com/

1. Progression of a high degree stenosis and sometimes layers of thrombi.

[pic 5]

Image: http://whatcardiologyis.com/

1. Who can have a CTO

The real prevalence of a CTO in the population is unknown. It is difficult to evaluate because there is a certain proportion of patients with CTO never undergoing any diagnostic because they are asymptomatic or with very few symptoms. The prevalence to have a CTO is however increasing with advancing patient age.

CTO are prevalent in the right coronary artery and least common in the circumflex artery.

1. How to treat a CTO

1. Who can do a CTO

CTO are quite complicated lesions that must be treated by experienced interventional cardiologists. It is advised to do a minimum of 50 CTOs per year to maintain competence to treat them. This translates into a model where only a limited number of operators and centers should be allowed to perform CTO treatment.

1. Factors for the success of a CTO recanalization

The factors for a successful intervention are depending on the patients’ characteristics and the training of the operator. The operator is able to evaluate the chances of a CTO recanalization looking at different factors evaluated in the J-CTO score table:

[pic 6]

1. The shape of the proximal cap
2. Calcification of the lesion
3. Tortuosity of the vessel
4. Length of the occluded segment

If one of the characteristics is present it will count as one point. A CTO with 4 points is the most difficult one.

However other factors are also relevant:

1. Longer occlusion duration
2. Previous failed attempt of CTO
3. Patient tolerance and comorbidities such as renal failure and muscular-skeletal pain.
4. Inability to see the distal part of the vessel.

1. Steps for CTO recanalization

CTO are complex lesions with totally blocked blood flow. So the doctor treating them should be very prepared. Before starting, he usually will decide what strategy to adopt to recanalize the artery. He should have different strategies in case his plan A might fail.

In order to treat a CTO optimally, there are steps to respect to decide if the doctor should treat it.

1. Assess a risk/benefits analysis to see if a CTO recanalization is required. The important factors to consider are:

• Age
• Symptoms
• Ischemic burden
• Renal function
• Ability to take dual antiplatelet therapy
• Previous radiation exposure
• Suitability for dual access sites
• The J-CTO score of the lesion

1. The doctor should consider the maximal consumption of contrast possible in regard to the patient’s age and other factors like renal function. Too much contrast can provoke renal failure.

1. He will decide after that the vascular access, femoral or radial, depending on his and the patient preferences.

1. He will decide which material to use.

1. At the end of the intervention, the patient should be treated with dual anti-platelet therapy: Clopidogrel and oral aspirin in order to inhibit blood clots in the coronary artery.

1. Techniques of revascularization

1. Antegrade approach

[pic 7]

The antegrade approach is the technique used most frequently by the operators. It is the one needing the less training of the operators. It means that you take the direct path to the occlusion. The guiding catheter is first inserted until the beginning of the coronary artery, at the end of the aorta. Then the guidewire is advanced to cross the lesion. It can be followed with a microcatheter or an OTW balloon for a better support of the guidewire. Once the lesion is crossed, a non-compliant balloon is inserted to dilate the CTO. A stent is placed afterwards.

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