Cardiovascular implantable electronic device (CIED) implantation has become a widespread procedure with a broad range of indications, including restoring atrioventricular synchrony, providing sudden death protection, and improving cardiac function through cardiac resynchronization therapy. Venous access is a critical part of this kind of procedure, and numerous techniques are available to reach central venous circulation. The cephalic vein cutdown technique is still being used in some centers as the standard for safe vein access,1 reducing the risk of pulmonary complications. However, this technique requires some surgical skills, and in most cases, there is not room for 2 or 3 leads inside a cephalic vein.2
Subclavian vein puncture using the Seldinger technique3 allows easy access to the central circulation but requires an intrathoracic needle pathway, leading to the risk of pneumothorax, hemothorax, and lead insulation damage.
In the past few years, the axillary vein has become the target for needle access for CIED implantation4 due to its easy accessibility, extrathoracic course, and very predictable anatomy. But the lack of surface anatomical landmarks for the axillary vein course has led to various strategies and techniques5 for achieving adequate vein cannulation without entering the intrathoracic space. Most of these techniques require fluoroscopy or contrast venography. Notwithstanding, even when using these strategies, pulmonary complications (eg, pneumothorax and hemothorax) still occur in clinical practice; this can lead to longer hospitalization time and rising health care costs, and represents a significant concern for CIED implantation.
Presently, ultrasound-guided access is considered the best practice for central line placement6,7 in intensive care units. Ultrasound guidance increases the success rate of these procedures, is associated with a low incidence of complications, and reduces bloodstream infection rates in intensive care patients. In some hospitals worldwide, it is not allowed to place a central line catheter without ultrasound guidance. Concomitantly, CIED implanters are now discovering ultrasound as a helpful tool in the operating room,8-10 allowing safe implantation with higher success rates,11 even in challenging anatomies, with a close to 0 pneumothorax rate.
As electrophysiologists, our first contact with ultrasound is often for femoral vein access. Usually, for femoral vein cannulation, a transversal view of the vessels will give enough information to safely guide the needle in most cases. With some practice, as needle visualization and guidance using ultrasound becomes easier, ultrasound-guided axillary vein access seems to be the logical next step. However, the sensitive nature of the structures in the vicinity of the axillary vein (eg, axillary artery, pleura, and axillary vein posterior wall) and the consequences of an inadvertent puncture of these structures requires a refined technique that would allow continuous needle (and vein) visualization to avoid the surrounding structures and increase success.
Our workflow is a 6-step approach that is supported with extensive experience; we have performed 425 implantations and a total of 849 punctures in the past 3 years. Since we started using this approach, no vascular access or pulmonary-related complications (pneumothorax or hemothorax) have been documented.
Step 1: Identify Axillary Vessels (Planning Your Approach)
Place a linear ultrasound probe in the upper chest wall, between the clavicle and shoulder, transverse to the course of axillary vessels (ie, ‘short-axis’ or ‘axial’ view). Avoid excessive pressure, or the vein will collapse. In this first step, the operator must be familiar with anterior chest wall ultrasound anatomy, including the relationship of main vessels with pleura and rib cage.
In a short-axis view of the axillary vessels (Video 1), close to the clavicle, the axillary vein is identifiable as a thin-walled, non-pulsatile, and compressible structure that runs caudally to the axillary artery (which is a pulsatile, non-compressible, round structure). When scanning from lateral to medial, the vein gets more superficial. In some cases, color Doppler can help to distinguish the vein and artery. Although possible, trying to puncture the vein in short-axis view will not give the necessary amount of information required to guide the needle with an appropriate angle (referred to as an ‘out-of-plane’ approach because the needle is not aligned with the ultrasound beam). Our first experience with the short-axis view approach naturally led us to change it to a long-axis in-plane approach (in other words, vein and needle are longitudinal and aligned to the ultrasound beam).
Short-axis view is recommended just to locate the vessels. Once the operator recognizes the vein and structures around it, they should keep the vein in the middle of the screen and turn the probe 90° clockwise to obtain a long-axis (ie, ‘longitudinal’ or ‘in-plane’) view of the vein (Video 2).
Step 2: Insert the Needle (How to Increase Needle Visualization)
Once the long-axis view of the vein is displayed on the screen, keep the probe steady and insert the needle through the intact skin just beneath the middle of the short side of the linear probe (Video 3). Many probes currently available on the market have a tiny mark that represents the ultrasound beam located in the center of the probe. Because the ultrasound beam is just 1 mm wide, it is crucial to start the puncture under the correct place to provide needle visualization even at the level of subdermal tissue and allow accurate needle tip tracking. Fine-tuning adjustments both by the hand holding the probe (eg, slight tilting and/or rotation) and by the hand holding the needle (eg, slight lateral adjustments plus back-and-forth jiggling) further optimize visualization of the needle tip from just below the skin surface down to the anterior wall of the vein.
As already alluded to, needle tip visualization is a crucial part of this technique. Thus, several software and equipment alterations have been created to enhance needle tip visualization. Currently, the majority of point-of-care ultrasound (POCUS) machines have enough image quality to provide full needle tip visualization. Some POCUS machines even have the ability to artificially enhance the needle image on the screen. The needle itself is another critical issue. The bevel is the most echogenic part of the needle due to its irregular shape. To take advantage of this, the bevel must be oriented upwards, toward the ultrasound beam. Usually, when correctly placed, the bevel of the needle can even create an “acoustic enhancement” artifact that will follow the needle tip. There are some special echogenic needles available, with a different texture at the final 10 mm, that can significantly enhance needle tip echogenicity. Notwithstanding, this 6-step approach is intended to be used without the need for any needle enhancement software or echogenic needle. The simplest POCUS machine available in the hospital and the needle provided by the pacemaker manufacturer will be everything that is needed.
The image created in the ultrasound machine is the reflection of the ultrasound beam from the transducer toward the tissue and again to the transducer. So, the needle visualization depends on how much it reflects the ultrasound beam to the transducer. Placing the needle in a shallow angle will improve needle visualization (by directing the reflection towards the transducer). Conversely, a steep angle will decrease the needle image because the ultrasound beam is being reflected far from the transducer. This can be an issue in obese patients, where the vein is usually deeper, requiring a steep angle approach.
Step 3: Advance the Needle (How to Visualize the Needle All the Time)
Once the vein and the needle tip are visible in subdermal tissue, advance the needle with the shallowest angle possible, toward the axillary vein. Usually, the vein gets more superficial from lateral to medial, allowing it to hit the vein close to the second rib (Video 4). If, during advancement, the needle tip is no longer visible, stop advancement, make a very gentle lateral movement with the needle, and try to visualize it again. Then, advance the needle. Do not trust the “tissue movement” as a mark of needle visualization. Precision in needle tip identification is essential.
Try to keep the probe as steady as possible. Moving the transducer or making slight tilt or rotation adjustments to track the needle are very useful maneuvers in some cases; however, these movements require much more practice from the operator to be employed. Once again, practicing this during femoral vessel access for other EP procedures will help prepare the operator to employ them during axillary vein access.
Step 4: Cannulating the Vein (How to Cross the Anterior Wall and Safely Avoid the Posterior Wall)
In the final approach, the needle tip will be in close contact with the axillary vein anterior wall. At this moment, the goal will be to cross the anterior wall without hitting the posterior wall. If performed correctly, a 100% safe puncture will have been achieved. However, some conditions can make this step more difficult than expected (Video 5).
Hypovolemia must be treated from the beginning of the procedure and can be evaluated by ultrasound. A substantial inspiratory vein collapse likely requires IV hydration to expand the intravascular space, allowing for a safe puncture. If the patient is in general anesthesia, keep positive end-expiratory pressure (PEEP) above 8 or 10 mmHg.
A highly compliant anterior wall might pose some problem to cross, demanding excessive force to perforate and potentially leading to posterior wall damage. A shallow needle angle can help in this step by allowing an “oblique” angle to the anterior wall, making it easier to cross (when compared to a perpendicular angle) and increasing the blood pool in front of the needle (which means the needle can be pushed safely). If still unable to cross, gently pushing the needle while decreasing the angle (ie, in a shallower angle) will allow for perforating the anterior wall, far from the posterior wall. In some situations, with maximum tenting of the anterior wall, a slight rotation of the needle can allow anterior wall perforation without further needle pushing.12
If the axillary veins are very thin, particularly in pediatric patients or in upgrades (the leads previously placed can considerably reduce the intravascular space), all the measures used before must be considered, but a 21-gauge needle from a micropuncture kit might be extremely useful to increase success rates.
Once in the vein, advance the guidewire and check the intravascular position using ultrasound. It can be seen by tilting the transducer cranially under the clavicle.
Step 5: Second Puncture (How to Make the Second Easier Than the First)
Once the first guidewire is in the intravascular space, the sequential punctures (second or third, depending on the device) will be performed in the same manner, but these tips can help you succeed (Video 6).
Place the ultrasound transducer along the axillary vein, as in the first puncture, and the first guidewire might be visible. If you perform the second puncture visualizing the first guidewire, try to aim the vein just beneath the first guidewire. It is easier to cross the anterior wall at that point (it often feels like the first wire keeps the anterior wall steady, diminishing tissue compliance). Another option is to perform the second puncture a few millimeters lower, where the first wire is not visible (but the vein is still on the screen). This approach has the advantage to cross the pectoral muscle and the vein a few millimeters far from the first guidewire, making lead suture easier.
Axillary veins are prone to spasm, and it can be a problem during implantation. A precise first puncture, with clear needle tip visualization and vein entering, is a game-changer, not because it avoids spasm (that generally occurs after some vein manipulation, in a second try), but because it gives a useful reference (first guidewire) to achieve the second puncture safely.
Once all punctures are done, you will be able to see the path of the guidewire through the superior vena cava on fluoroscopy and adjust it if necessary. Notice that fluoroscopy was not required until this moment. In other words, this approach allows for reduction of radiation exposure both for the patient and operator (particularly the operator’s hands).
Step 6: Planning the Incision (Where to Place the Incision)
To facilitate the procedural workflow, the incision must be placed on top of the point where the guidewires cross the pectoralis major. The rationale of this step is to ease access to the leads during implantation and help anchor the leads to the muscle, because that point is precisely where the suture sleeves will be placed. Ultrasound can help identify the very point where the guidewire perforated the muscle (Video 7). In a transversal view, follow the guidewire path from the skin to the vein, keeping the guidewire (2 echogenic dots) in the middle of the screen. Find a point where those dots are inside the pectoralis major. It is useful to place the medial border of the incision 1 cm medial to this point.
Open the wound in a standard fashion, and once the fascia of pectoralis major has been reached, firmly hold the wire near the muscle and pull the proximal part of the wire into the skin. Now, with all wires inside the wound, the implantation can proceed with the technique of choice. Video 8 shows a full procedure demonstrating all the steps discussed in this approach.
Ultrasound-guided axillary vein puncture is a game-changer. It is highly beneficial to patients and health care providers. The hardware needed to perform it is already available in every hospital, and the learning curve to master this technique is relatively short. It reduces radiation exposure to health care providers, risk of complications, and hospitalization time after the procedure. Our goal is to share this 6-step approach with new and old implanters, to achieve a safer procedure.
Acknowledgements: I would like to thank all EP staff at Pró-Cardíaco Hospital (Drs. Eduardo Saad, Luiz Eduardo Camanho, Luiz Antonio Oliveira Inácio Junior, Lucas Carvalho Dias, and Gustavo Vignoli) as well as the anesthesiologists (Drs. Paulo Maldonado, Bruno Vilanova, and Cesar Monteiro) and the EP nurses who played an amazing role supporting our team (Carla Peixoto, Natalia Quirino, and Margarida Vicente).
Disclosures: Dr. Slater has no conflicts of interest to report regarding the content herein.
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