In - Depth Analysis of Key Points of Catheter Technology in Vascular Interventional Procedures
Apr 24,2025
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Catheters can be roughly divided into angiographic catheters and therapeutic catheters according to their uses and purposes: Angiographic catheters are conventional equipment for ordinary diagnostic angiography, mainly used for diagnosis to evaluate the anatomical morphology of the vascular bed. Therapeutic catheters generally include balloon catheters, guiding catheters, thrombolytic catheters, thrombectomy catheters, etc. However, the two types of catheters cannot be strictly distinguished. For example, angiographic catheters commonly used for diagnosis sometimes also have certain therapeutic purposes, such as delivering drugs and releasing coils.
01 Angiographic Catheters
Catheter Design and Functional Use
Angiographic catheters generally have a long, slender, and hollow tubular shape with a thin wall. Their external ends can be easily connected to standard syringes or high - pressure injectors. Currently, such catheters are mostly made of high - quality materials such as polytetrafluoroethylene, polyurethane, polyethylene, and nylon. To optimize the catheter advancement performance, their surfaces are coated with different types of hydrophilic coatings. At the same time, the metal wire braided structure added to the middle layer of the catheter wall can significantly enhance the durability, strength, anti - bending ability, and torsional control sensitivity of the catheter. Angiographic catheters have diverse functions, mainly including:
Clearly observing the vascular structure by injecting contrast agents.
Measuring pressure and collecting valuable hemodynamic data.
Transporting and precisely releasing drugs or embolic materials.
Temporarily acting as guiding catheters in specific surgeries. The key to identifying different catheters lies in the unique shape design of their distal ends.
Catheter Classification
According to the application purposes of different catheters, angiographic catheters can be roughly divided into two categories: non - selective angiographic catheters and selective angiographic catheters.
Non - selective Angiographic Catheters
Non - selective angiographic catheters, such as pigtail catheters and tennis racket catheters, are commonly used for non - selective angiography of large blood vessels (such as the aorta, pulmonary artery, vena cava, and cardiac chambers). The multi - side - hole design at their distal ends supports high - speed and large - flow contrast agent injection. In addition, straight multi - side - hole catheters also belong to this category and are suitable for selective angiography of the carotid artery, iliofemoral artery, and inferior vena cava, which can effectively increase the flow rate and velocity of the contrast agent.
Selective Angiographic Catheters
Selective angiographic catheters exhibit more diverse morphological changes. Their distal ends are designed into various pre - formed styles with single curves and complex reverse curves, and only one end - hole is set at the end. They are specifically designed for selective vascular intubation and angiography of specific aortic branches. Compared with non - selective catheters, the contrast agent flow rate and velocity of selective catheters are usually lower. Common selective angiographic catheters include Vertebral (vertebral artery), Headhunter, Simmons series, Cobra, Shepherd, Mikaelsson abdominal, Bentson JB, Vitek, Mani, and RDC (renal double - curve) catheters, etc. (see Figure 1).
Simmons 1
JB2
Simmons 2
Catheter Specifications and Operating Procedures
Catheter specifications are usually classified based on their outer diameter size, and the common range is concentrated between 4 and 7 French (F). In routine angiography examinations, operators generally prefer to choose catheters with a smaller outer diameter, especially 4F and 5F specifications. Among them, the 5F catheter, due to its relatively large inner lumen space, can sometimes temporarily act as a guiding catheter to assist micro - catheters in performing super - selective intubation angiography tasks. Catheter designs show rich diversity in hole types and lengths. When performing selective angiography operations, end - hole catheters are the preferred type. The side - hole design not only helps to increase the flow rate and velocity of the contrast agent but also enhances the stability of the catheter under high - pressure injection conditions, effectively avoiding possible damage to the vascular wall caused by large - amplitude catheter swings. According to the angiography requirements of different anatomical sites, the catheter length settings vary. For abdominal aortic positioning angiography, the catheter length is usually set between 60 and 80 cm. For examinations of the thoracic aorta and carotid artery regions, longer catheters are required, with a length range between 100 and 120 cm. To ensure the smooth operation of the catheter and extend its service life, the catheter needs to be kept moist and thoroughly flushed before entering the body. During the operation, intermittent flushing in a timely manner is also crucial, which can further extend the service life of the catheter and effectively reduce the formation of blood clots at the catheter tip, thus ensuring the smooth progress of the angiography process.
02 Balloon Catheters
The balloon catheters discussed in this article specifically refer to those that play a role in selective intubation (with the help of floating function) and temporary blood flow occlusion (i.e., occlusion function), excluding catheters specifically used for balloon angioplasty.
Working Principle of Balloon Catheters
The core mechanism of balloon catheters is that the balloon structure is filled by injecting carbon dioxide gas or diluted contrast media. The filled balloon can float autonomously along the direction of natural blood flow to the target treatment area by adapting to hemodynamic characteristics. For example, the Berman catheter, a typical representative of such devices, is widely used in interventional diagnosis and treatment of the right heart system and pulmonary angiography. In the interventional treatment of high - flow vascular lesions such as arteriovenous fistulas or arteriovenous malformations, such balloon catheters, with their downstream - floating characteristics, can not only achieve ultra - precise vascular intubation positioning but also enhance the imaging quality through the local blood flow blocking effect. Their clinical advantages are more reflected in that they can accurately anchor and release embolic materials (such as coils) during embolization treatment, effectively avoiding the risk of distal misembolization caused by blood flow impact. Especially when the feeding artery segment is short and it is difficult to stably place traditional embolization catheters, the balloon catheter can be temporarily fixed in the target blood vessel and release embolic substances directly through its end opening, significantly reducing the incidence of reflux misembolization. In addition, the temporary blood flow occlusion function of such catheters also has crucial value in the emergency treatment of ruptured abdominal aortic aneurysms. By quickly establishing local blood flow occlusion, balloon catheters can effectively control active bleeding, greatly reducing the surgical risk of emergency surgical intervention and winning a golden time window for subsequent treatment. This dual - function characteristic makes it show unique therapeutic advantages in the field of vascular intervention.
03 Guiding Catheters
As a key channel for delivering various devices in interventional surgeries, guiding catheters have multiple functions, including delivering devices, providing support, monitoring pressure, and injecting contrast agents. Their rational selection is a core element to ensure the smooth implementation of balloon dilation and stent implantation. Although guiding catheters are similar in appearance to angiographic catheters, there are essential differences in technical requirements. They need to ensure a sufficient inner diameter to meet the delivery requirements of interventional devices while strictly controlling the outer diameter to reduce the risk of complications at the puncture site. This contradictory requirement of "small outer diameter, large inner lumen" makes guiding catheters pay more attention to balance in material selection and structure design. They need to ensure anti - bending and anti - torsion handling performance while maintaining sufficient axial support force. These multi - dimensional technical considerations determine that the design standards of guiding catheters are much higher than those of ordinary angiographic catheters.
04 Catheter Operation Skills
Generally, the diameter of the catheter and the guide wire need to be matched. The catheter should advance along the guide wire, and during the operation, the guide wire should be continuously pulled to prevent the catheter from continuously sliding forward. Do not advance the catheter when the guide wire is not fully straightened. When using a hydrophilic guide wire, tools such as hemostatic forceps should be used to clamp the rear end of the guide wire to prevent the guide wire from suddenly moving forward in the catheter. When advancing the catheter, hold the catheter tightly and push it forward step by step in short distances. The distance between the part of the catheter operated outside the body and the sheath tube should not be too far, otherwise, the catheter and the guide wire may bend. The catheter may encounter difficulties in advancement when passing through the softer part of the guide wire. When the catheter reaches the soft section of the guide wire, it may maintain its original shape, resulting in a significant decrease in its advancement performance. At this time, the guide wire should be continuously advanced to ensure that the catheter always advances on the harder part of the guide wire. If the catheter still cannot be advanced on the hard section of the guide wire, an arterial dilator needs to be advanced to further dilate the artery, or a guide wire with a higher hardness needs to be replaced to provide additional support for the catheter. If the advancement performance of the catheter weakens after it enters the blood vessel, consider replacing a guide wire with a greater hardness. If the catheter cannot reach the lesion site along the guide wire, the possible reasons include high lesion resistance, severe stenosis of the lesion, the guide wire blocking the remaining arterial channel, or the guide wire entering the sub - intimal space of the blood vessel. When the blood vessel lumen is tortuous or the distance between the catheter tip and the access point is long, making it difficult for the catheter to pass through, the guide wire should be gently and smoothly withdrawn, and the catheter should be advanced when a small resistance is encountered at the catheter tip. If it is close to the lesion site, it can reach the intended operation position. Avoid pulling the guide wire out of the intended blood vessel path. When advancing the catheter, ensure that the catheter does not cross the guide wire, and avoid catheter deformation during the advancement process. If the guide wire and the catheter bend frequently, select a guide wire with a higher hardness for support. Another method is to keep the guide wire in place, withdraw the catheter, insert a longer sheath tube to reduce friction, and then re - insert the catheter through the sheath tube.
05 Precautions for Catheter Operation
Before the catheter enters the body, it should be flushed with heparin - saline solution outside the body to empty any solids, blood clots, including air bubbles, in the catheter lumen.
When using a catheter, carefully select the appropriate size, length, and tip shape according to the angiographic site and experience.
After successfully placing the guide wire through the vascular puncture site, before placing the dilator, sheath tube, or catheter for hemostasis, carefully press the puncture site with your fingers to perform arterial hemostasis. Correct compression can effectively reduce the formation of hematomas at the puncture site.
Dilate the epidermis to an appropriate size with mosquito forceps to facilitate the subsequent entry of the dilator and catheter.
Push the dilator or catheter into the blood vessel along the harder part of the guide wire.
Advance the catheter step by step under fluoroscopy, several centimeters each time.
Pay attention to the resistance and feel of advancement during the process of advancing the catheter and guide wire to avoid entering the sub - intimal dissection channel.
Intermittently pull the guide wire during the operation to prevent the guide wire and the catheter from advancing simultaneously.
If it is difficult for the catheter to reach the target position smoothly due to a long advancement distance, it is usually due to high friction. At this time, place a long sheath, replace the hard guide wire, or select another arterial puncture site.
During the in - vivo operation of the catheter, intermittently flush the catheter with heparin - saline solution to prevent the formation of small blood clots on the catheter wall.
Do not inject any substances (heparin - saline solution and contrast agent) into the catheter until there is blood reflux at the outer end of the catheter. Under normal blood pressure, there is usually blood reflux in the catheter, unless the catheter tip is embedded or attached to the vascular wall.
Before high - pressure injection of the contrast agent, continuously adjust the position of the catheter tip under fluoroscopy to ensure that it is free in the vascular lumen. Otherwise, it may induce dissection or perforation.
Before high - pressure injection of the contrast agent, also aspirate the contrast agent back into the syringe until there is blood reflux to avoid air bubbles at the interface between the syringe and the catheter end from entering the body.
If the catheter end is knotted, pass a relatively hard guide wire through the catheter to untie the knot.
To determine that the catheter is in the vascular lumen, in addition to judging by blood reflux, the free mobility of the catheter tip in the vascular lumen can also be observed by rotating the catheter outside the body under fluoroscopy.
When injecting a small amount of contrast agent, the contrast agent should be quickly washed and diluted by the blood flow instead of remaining on the vascular wall causing patchy staining. At this time, the catheter is in the free vascular lumen.
After removing the guide wire, if the position of the catheter tip is uncertain under fluoroscopy, inject a small amount of contrast agent, which can help improve the visibility of the catheter.
When removing the catheter or performing an exchange operation, the guide wire should be fixed in place, and the catheter should be withdrawn at the same time. Intermittently check whether the guide wire is in place under fluoroscopy.
