About angioplasties and stenting:

How does a balloon work?
Do you keep the balloon in or take it out?
What happens to all the pieces of cholesterol that have
    been broken?
What is stenting?
How many vessels can be stented?
Do you take out the stent if it does not work?
What is rotorooters of the heart?
These are only a few of the long chain of questions that
    patients usually have with reference to this subject.

Before angioplasty we obtain an angiogram in multiple views. The angiogram is then carefully reviewed to see how many blockages there are, the location, the degree of stenosis and morphology of these blockages. Correlating the symptoms and the region of ischemia, a decision is made to open the appropriate blockages, employing angioplasty. In general, left main stenosis and multiple blockages involving all three major vessels, and diffuse blockages are not attempted for elective angioplasty.

Angioplasty is the endovascular remodeling of a clogged vessel by inflating a balloon against the blockage. Here, a special catheter very similar to a diagnostic angiography catheter is advanced to the ostia of the target coronary artery via the femoral artery or brachial artery. This tube has an internal diameter of about 3.0 mm. This catheter serves as a transport conduit for the necessary wires, balloons, stents, and other required hardware. It is through this same catheter that all necessary radiopaque contrast materials and medications are administered directly into the coronary arteries.

Once we have identified a target lesion to be opened up, a thin (14/1000 of an inch) flexible guidewire is slowly advanced through the artery, across the blockage, and the wire is parked in the whole extent of the vessel. Angioplasty balloons are available in various diameters (1.5 mm to 5.5 mm) and lengths (15 mm to 40 mm). An appropriate sized deflated balloon is then advanced to the blockage area by railing through the guidewire. The balloon is then inflated to break and compress the plaque against the wall. The balloon can be inflated anywhere from 3 to 24 atmospheres of pressure, and kept inflated in the arterial lumen from a few seconds to several minutes. When the balloon is inflated, the blood supply through that vessel is temporarily cut off. Then, the patient can have ischemic symptoms (chest pain, tightness, etc.) The balloon is then deflated and railed out through the existing guidewire. In balloon angioplasty, the cholesterol plaques are not taken out. They are ruptured and compressed against the wall. This area continues to heal by the body’s own remodeling process, and finally covered by healthy endothelium from either end of the treatment area.

Balloon angioplasty has a 95% primary success rate, but the long-term patency is only 60%.

A stent is a stainless steel slotted tube or coil meshwork made in different diameters and lengths. They are mounted on an angioplasty balloon in the deflated state. The stent is advanced via the guidewire railing system, and taken to the desired treatment area. The balloon is then inflated to expand the stent. The expanding power of the balloon deploys the stent into the internal layers of the artery. The balloon is then deflated and taken out. The expanded deployed stent remains in this vessel scaffolding it from within. The stent remains in the vessel forever. The guidewire is then finally pulled out. The primary success rate of coronary stenting is over 99%, and the long-term patency is about 80%. That is the reason why stenting is used in about 80% of all percutaneous coronary interventions. We can stent several vessels at the same sitting, or as a staged procedure in certain instances.

Fig. 12 A: RCA of a 55-year-old female - Selective right coronary angiography showing a high-grade lesion of the mid right coronary artery. AR - aortic root. C - catheter. RCA - right coronary artery. Arrow - 90% stenosis of the mid right coronary artery.

Fig. 12 B: Wiring W - wire. A 0.014 inch diameter stainless steel guidewire is passed through the blockage and parked all the way to the distal portion of the right coronary artery. This wire will function as a “monorail” for the advancement of the balloon and stent.

Fig. 12 C: Balloon angioplasty – Predilatation B – balloon. W – wire. A 20 mm long and 2.5 mm diameter (when inflated) balloon is placed at the site of the blockage and inflated up to 10 atmospheres. The balloon will split and compress the cholesterol plaque creating a space. In effect, this is balloon angioplasty. In this case we might call it predilatation, as we are planning to put a stent at this site.

Fig. 12 D: Positioning of the stent A stent before deployment - A 3.5 mm diameter and 18 mm long stent mounted on a deflated balloon is placed at the original site of the blockage.

Fig. 12 E: Deployment of the stent S – stent. The stent-mounted balloon is then inflated up to 16 atmospheres for 30 seconds. The balloon is then deflated and taken out. The stent remains in the lumen of the artery scaffolding it from within.

Fig. 12 F: The stented vessel The balloon and wire are now removed, and the stent is deployed in the target area. The angiogram shows a widely patent vessel with no evidence of any residual stenosis.

Fig. 13 A: White arrows - The left coronary angiogram of a 60-year-old woman having a complex stenosis involving the LAD and large diagonal branch.

The LAD-diagonal system was then subjected for angioplasty. The two vessels were then wired as described before. Then, two stents were simultaneously advanced into these blockages and placed in position. The two stents were then simultaneously inflated up to 14 atmospheres. Following deployment of the stent, the balloons were taken out. As shown in figure 13 B, following stenting, the two vessels are widely patent with no evidence of any residual stenosis. In this technique, two stents are placed side-by-side with their proximal ends touching and kissing each other— this technique is termed kissing stent.

Fig. 13 B: The LAD-diagonal lesions are now fully reopened by simultaneous application of two stents in the treatment area – kissing stents, as marked by the white arrows.

Fig. 14 A: Left coronary angiogram showing a proximal eccentric ulcerated 50% stenosis shown by the two black arrows.

Fig. 14 B: Intravascular ultrasound showing plaque burden in the lumen of the coronary artery. C – catheter. Black arrow – bulging of the coronary artery by heavy plaque load. White arrow – possible point of rupture of a soft plaque.

Intravascular ultrasound is exceptionally useful to study the morphology and extent of coronary lesions in selected cases. Here, the angiogram showed only a 50% eccentric lesion, which is to be treated medically as was done in this case. However, the angiogram underestimated the severity of the lesion, and didn’t give a clue as to the instability of the plaque. The intravascular ultrasound showed that the plaque burden has already remodeled the coronary artery making the cross-sectional view of oval shape rather than circular, and that the plaque is soft, lipid-rich, and without calcium.

Fig. 14 C: Following stenting, the left anterior descending artery is widely patent as shown by the three black arrows. Moreover, we can see the point of plaque rupture at the 11 o’clock position – small white arrow. It was this rupture that resulted in acute coronary syndrome in this patient.

Fig. 15 A: Selective left coronary angiogram shows subtotal occlusion of a large left anterior descending coronary artery, as shown by the white arrows.

Fig. 15 B: Following coronary stenting, the LAD is widely patent with all its branches as shown by the white arrows.

Such patients are not candidates for thrombolytic therapy. They are best treated by medical stabilization and emergency angioplasty with or without stenting. This procedure of directly opening up a clogged vessel in a patient without giving thrombolytic therapy is called primary angioplasty or primary stenting if a stent is used.

In addition to balloon angioplasty and stenting, there are several other adjuncts we use in an interventional lab to offer patients the most optimal care.

Directional atherectomy is a cutting device occasionally used to take out pieces of atherosclerotic plaques from the coronary arteries.

Rotational atherectomy (Rotablation device) is a diamond-head, pear-shaped, metallic ball called a bur that is advanced to the coronary artery by a guidewire railing system. The bur is then drilled through the plaque at a speed of 150,000 -180,000 rotations per minute. The drilling will make the plaque into extremely small particles of 1 micron or less. These particles will flow down distally, and eventually be engulfed by the other cells and destroyed (phagocytosis).

Another important device that we use in the lab is an intracoronary ultrasound device. A small transducer of 1.5 mm in size is advanced through the coronary artery via a guidewire railing system. The piezoelectric crystals in the transducer are then activated to obtain ultrasound images of the artery. This device is extremely useful in several instances where we want to learn more about a given lesion before and after angioplasty or stenting.