Percutaneous coronary intervention (PCI) is now one of the most common medical procedures in the world. The ‘usual’ set up for PCI is simple. First, a short plastic tube called a sheath is placed in one of the arteries. Second, a longer plastic tube (called a guide catheter or guider) is placed through the sheath and reaches the coronary arteries of the heart via the body’s arterial system. After this, a thin wire (typically with a diameter of 0.014”) is placed in the coronary artery, through the narrowing or stenosis that is to be the target of the PCI. Finally, balloons, stents, and other equipment are pushed along this wire so as to dilate and treat this stenosis.
Currently, the majority of PCI is performed with a sheath in the artery that runs along the patient’s wrist. This artery is called the radial artery, and PCI performed in this fashion is termed transradial PCI (TRI). Transradial PCI has been shown to be safer, and have better outcomes than PCI performed through a sheath placed in the groin, and therefore is currently recommended by international guidelines as the default approach to PCI.
However, we know that the radial artery varies in size between individuals. In some individuals, the radial artery is of small calibre, and hence placing a sheath in the artery can be uncomfortable, and may even lead to long term problems like damage to the artery. Because of this, there was a drive to ‘downsize’ the equipment used in TRI so as to make the technique applicable to more people, and reduce the risk of complications.
An illustration of a balloon catheter in the coronary artery.
The Japanese have been at the forefront of this movement, and have pioneered many of the techniques and technological innovations for ‘Slender’ TRI. Many of these innovations have now spread around the world and are used more commonly in daily practice. Every component of the ‘usual’ PCI set up has been targeted so as to achieve the overarching aim of a more ‘elegant’ and safe procedure.
There are now sheaths that have thinner walls than before, yet still provide the necessary support for the guide catheters to be inserted into the artery. Because the wall is thinner, the overall diameter of these sheaths is less, hence they are easier to insert in patients who have smaller radial arteries.
Most PCI are currently performed with a guide catheter that has an inner diameter of 2mm (termed a 6 French guider). However, for most cases, a smaller guider sized guider (typically 5 French) can actually be used to perform TRI safely. As a 5 French guider is smaller, the sheath required
is also smaller, hence the overall size of the system is smaller than when a conventional 6 French guider is used.
Additionally, there are now guide catheters that can be used without a sheath. These catheters have a special design and coating so that they are less likely to cause damage to the artery. These ‘sheathless’ guiders are inserted directly into the radial artery and because a sheath is not required, the overall size of the system is significantly less than when a sheath is used.
In Japan, companies have also developed special wires that are of smaller diameter than conventional guidewires, as well as the corresponding equipment (such as balloons) to be used with them. Because of this innovation, TRI can be performed through smaller size guide catheters such as 4 French guiders.
The ‘sheathless’ guide catheter.
The main issue with downsizing is that smaller equipment leads to less force and support during TRI. This can be an issue when dealing with more complex cases. Because of this, techniques were developed such as the use of anchor wires and anchor balloons, special guider manipulation and configuration, and other novel modifications. These techniques are now used routinely in all PCI, demonstrating how good ideas will quickly be adopted by all.
However, there are limitations to the ‘slender’ philosophy and there are times when ‘bigger is better’. Some PCI cases are highly complex and require special techniques and equipment that cannot fit into current ‘slender’ technology. For instance, there are times when a balloon catheter and an ultrasound catheter need to be used simultaneously – these catheters cannot both fit into most 6 French guide catheters currently. Similarly, rotational atherectomy where a special drill is used to modify a very hard and calcified stenosis usually requires at least a 6 French guider system.
In NHCS, many of these technologies are available for carrying out ‘slender’ PCI. For example, ‘slender’ sheath are now the default sheath in daily practice in NHCS, and 5 French systems as well as ‘sheathless’ guide catheters are used in more cases. While there is access to many technologies, it is crucial to assess the appropriateness of methods for each case – whether be it conventional or “slender” technology.
Catch live demonstrations covering lithotripsy and orbital atherectomy cases, and specific sessions featuring key techniques such as TRI, and also the ‘slender’ techniques. The ‘slender’ techniques session is a joint session with the Slender Club Japan (SCJ), who are universally acknowledged to be the pioneers of the ‘slender’ movement.
Singapore LIVE (SingLIVE) is Asia’s pre-eminent annual live course in cardiac interventions, and has expanded its reach and influence over the last 28 years to include many Asian key opinion leaders and experts, disseminating key opinions and practices which made the course highly relevant for many cardiologists in the region.
SingLIVE 2020 will be held from 15 to 17 January 2020 at Raffles City Convention Centre. More information can be found on
Register before 29 Nov 2019 to enjoy the early bird registration fees!
This article is from Murmurs Issue 34 (May – Aug 2019). Click
here to read the full issue.