During his Interventional Cardiology Fellowship at the Dorset Heart Centre, Royal Bournemouth Hospital (U.K.), Dr Omar Rana received extensive training in the following techniques.
- Coronary Angioplasty and Stent Insertion
The term angioplasty means using a balloon to stretch open a narrowed or blocked artery. However, most modern angioplasty procedures also involve inserting a short metallic mesh tube, called a stent, into the artery during the procedure. The stent is left in place permanently to allow blood to flow more freely.
Coronary angioplasty is sometimes known as percutaneous transluminal coronary angioplasty (PTCA). The combination of coronary angioplasty with stenting is usually referred to as percutaneous coronary intervention (PCI).
There are 3 kinds of stents commercially available:
- Bare metal stents (no drug coating).
- Drug eluting stents (drug-coated stents)
- Bioresorbable scaffolds (These stents are resorbed over a 3-5 year period).
Figure 1: A Bare Metal Stent
Figure 2: A Drug Eluting Stent
Figure 3: A Bioresorbable Scaffold.
Figure 4: Illustration of how a bioresorbable scaffold gets absorbed over time in comparison to a drug eluting metallic stent which does not.
- Intravascular Ultrasound
Intravascular ultrasound (IVUS) is an invasive procedure, performed along with cardiac catheterization during which a small sound probe (transducer) on the tip of a coronary catheter is introduced into the coronary arteries. Subsequently, with the help of high-frequency sound waves, detailed images of the interior walls of the arteries can be visualized. Where angiography shows a two-dimensional silhouette of the interior of the coronary arteries, IVUS shows a cross-section of both the interior, and the layers of the artery wall itself. Dr Omar Rana has been involved in cutting-edge scientific research high-lighting the importance of IVUS and assessing stent expansion which has been published.
Figure 5: Intravascular Ultrasound image of a coronary artery following stent deployment which shows a fully deployed and well-apposed stent.
- Pressure Wire Assessment
The pressure wire has a pressure sensor near the end. The wire is introduced into the coronary artery and negotiated across the narrowed artery. Following this the difference between the pressure measured in the artery beyond the narrowing is compared with that in the aorta (main blood vessel). The difference between the two can be expressed as a ratio called the fractional flow reserve (FFR). This is measured at rest and following the administration of either an infusion or bolus of adenosine. This leads to an increase in the blood flow through the coronary circulation and simulates the situation of exercise.
Measurement of the FFR can be calculated. SA value of greater than 0.8 is considered normal and a value of less than 0.8 is abnormal warranting treatment in the form of stents or coronary artery bypass grafting.
- Optical Coherence Tomography (OCT)
Optical coherence tomography (OCT) is a diagnostic procedure that is used in combination with coronary angiography. The technique uses near-infrared light to create images of the inside of your blood vessels. Unlike ultrasound, which uses sound waves to produce an image of the blood vessels, OCT uses light. With OCT, we can obtain images of the blood vessels that are about the same as if they were looking under a microscope (Figure 6).
OCT uses near-infrared light to create images of the inside of the coronary arteries. The technique delivers such high-resolution images because it uses light instead of sound waves. A beam of light is directed at the artery, and some of the light reflects from inside the artery tissue and some of it scatters. This scattered light causes something called “glare.” Using OCT, the glare can be filtered out. Even the smallest amount of reflected light that is not scattered can be detected and used to form the image of the coronary artery. In fact, OCT allows cardiologists to see in 10 times more detail the inside an artery than if they were using intravascular ultrasound.
Figure 6: An optical coherence tomography image of a coronary artery demonstrating exquisitely the various vessel wall layers.
Figure 7: A case examples of how the superior image quality of optical coherence tomography can help diagnose any issues during or following stent insertion.
- Rotational Atherectomy (Rotablation)
Rotational atherectomy (Figure 8) uses the principle of differential cutting to ‘chisel’ calcified coronary arteries from the inside to allow the deployment of stents in otherwise very stiff and non-compliant arteries and completion of the angioplasty procedure safely and effectively. A diamond-studded burr is used to debulk calcified coronary lesions as shown in Figure 9. Dr Omar Rana has been full trained in using this equipment and has safely treated over a hundred cases using this technique. He is the only interventional cardiologist in Punjab, to have so much experience with this technique (Figure 10).
Figure 8: The various parts of a rotablator.
Figure 9: Illustration of how a rotablator burr works.
Figure 10: Case example where Excimer Laser Coronary Atherectomy was used in conjunction with Rotational Atherectomy. Final result is seen in (F).
- Excimer Laser Coronary Atherectomy (ELCA)
Over the last decade, Excimer Laser Coronary Atherectomy (ELCA) has come in the fore-front to treat cases such as a non-crossable narrowing (where balloons or stents cannot cross a narrowing in the artery), a non-dilatable narrowing (where a balloon cannot fully expand a narrowing), under-expanded stents (due a ring of calcium deposits in the vessel wall architecture, not allowing a stent to fully expand and selected cases of stent thrombosis. Dr Omar Rana had the unique opportunity to work at the Dorset Heart Centre, Royal Bournemouth Hospital (U.K.) which is the European reference centre for ELCA. During his Fellowship, he was involved in organizing several educational workshops. He has been fully trained in using this technique and can perform this independently.
Figure 11: Illustration to explain the principles of Excimer Laser Coronary Atherectomy.
Figure 12: Case example to demonstate the use of Excimer Laser Coronary Atherectomy in treating a non-crossable right coronary artery narrowing with the final result in (E).
- Dedicated Bifurcation Stents
Over the last few years, dedicated bifurcation stents have been developed to treat coronary bifurcations (where a main vessel divides into daughter main vessel and a side branch). The dedicated bifurcation stent increasingly being used world-wide is called the AXXESSTM stent. Dr Omar Rana has received full training in using this stent and has been involved in registry following patients who have received this device. The results of this registry are being published.
Figure 13: Illustration to explain the concept of an AXXESSTM dedicated bifurcation stent.
Figure 14: Case examples of bifurcations lesions that have been treated with the AXXESSTM dedicated bifurcations stent. Right coronary artery before and after stenting (A and B). Left circumflex coronary artery before and after stenting (C and D). Left anterior descending artery before and after stenting (E and F).
- Intra-aortic Balloon Pump Insertion
Some patients have a significantly low blood pressure when the present with a heart attack. Such patients may benefit from the insertion of an intra-aortic balloon pump (IABP). This device helps improve the blood pressure and reduces the amount of work done b an already struggling heart. This device is introduced following the application of a local anaesthetic through an artery in the patient’s groin.
The balloon is inflated with the help of helium gas which improves the blood circulation through the arteries of patient’s heart and subsequently deflates. This sequential inflation and deflation of the IABP continues and can also improve the cardiac output as illustrated in Figure 15.
Figure 15: Schematic diagram illustrating the mechanism of action of an intra-aortic balloon pump. The IABP inflates during diastole leading to an improved circulation in the coronary arteries followed by deflation which allows blood circulation to the peripheries.
- Intra-corporeal Left Ventricular Assist (ImpellaTM) Device
This is a highly mechanistic device that can be placed percutaneously through the groin artery using X-ray screening and following the administration of local anaesthetic. The device rests inside the left ventricle (pumping chamber of the heart) and allows uninterrupted blood flow to the aorta and the peripheries. In this manner the ImpellaTM device can increase the cardiac output significantly. This device is currently available in 3 sizes which can give a cardiac output of 2.5, 3.5 or 5 litres/minute.
Figure 16: Schematic showing the mechanism behind an ImpellaTM device.
Figure 17: Case example of a patient where the last remaining coronary artery was treated with the help of an ImpellaTM device (asterisk, A). We had to treat the left anterior descending artery with the help of excimer laser coronary atherectomy (B) followed by rotational atherectomy (D) and the insertion of drug eluting stents (E) with the final result (F).
- Chronic Total Occlusions
Some patients may suffer from angina (pain from the heart) due to arteries that have been blocked for months to years. These are known as chronic total occlusions (CTO). Dr Omar Rana has received specialized training from the world expert in chronic total occlusions Dr Suneel Talwar during his 2-year Interventional Fellowship and has had the opportunity to interact and work with and learn from leading American and European CTO experts including Dr Simon Walsh, Dr Colm Hanratty, Dr Peter O’Kane and Dr James Spratt. Dr Omar Rana is a regular attended at the EuroCTO club’s annual conference and has numerous publications in this arena. He has been fully trained in the use of the following techniques:
Antegrade wire escalation technique.
Antegrade dissection and re-entry technique.
Use of the Sting-ray balloon system.
Use of the CrossBoss device.
Retrograde wire escalation technique.
Retrograde dissection and re-entry technique.