An introducer sheath (also called a vascular sheath or arterial sheath) is a short, hollow plastic tube inserted into a blood vessel at the start of a cardiac catheterisation or other interventional procedure. It acts as a conduit, maintaining reliable vascular access throughout the procedure and protecting the vessel wall as catheters and other instruments are exchanged. A haemostatic valve prevents blood from leaking back around the instruments.
Sheaths are most commonly placed in the radial artery at the wrist (for coronary angiography and PCI) or the femoral artery in the groin (for larger or more complex interventional procedures). They are sized in French (Fr) units, describing the outer diameter; larger sheaths accommodate larger devices. After the procedure, the sheath is removed and haemostasis is achieved: for radial access, a dedicated compression band is applied for 2 to 4 hours; for femoral access, manual pressure or a vascular closure device is typically used.
Complications directly related to sheath insertion are uncommon but include haematoma (bruising) at the puncture site, radial artery spasm (particularly problematic in small or tortuous radial arteries), and, rarely, arterial occlusion or pseudoaneurysm formation. In the intensive care unit following cardiac arrest, the sheath site may be left in place temporarily to allow repeat access or ongoing arterial blood pressure monitoring.
For patients who have undergone coronary angiography or PCI, the sheath insertion site will be bandaged and should be kept clean and dry. Any significant bleeding, bruising, swelling, or discomfort at the site after discharge should be reported to the hospital or GP promptly.
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