Gaining Access:Arterial intervention techniques and special patient needs
Vascular complications associated with arterial access have long been recognized to occur during cardiac catheterization and percutaneous intervention procedures. In fact, most complications occur from the initial puncture or at the removal of the sheath. Specific problems include vessel thrombosis, distal embolization, dissection, or poorly controlled bleeding at the puncture site.2 Managing these potential complications has become more challenging with the increasing use of anticoagulation therapy that may include glycoprotein IIb/IIIa inhibitors. This is why meticulous attention to proper vascular access is so essential in helping to yield successful results.
Identifying Potential Patient Risks
In order to properly access the artery, you must first assess the special needs of the patient. Special attention should be given to identifying patients with peripheral vascular disease, older age and concominant anticoagulation use. These conditions are associated with a higher risk of procedure-related complications.2 Awareness of these conditions prior to the procedure can minimize these risks.
A thorough patient history inclusive of past procedures, surgeries and response to medications are key elements to optimal patient care. Knowledge of co-morbid conditions such as diabetes, hypertension, stroke, smoking and coronary artery disease will prepare the operator to meet some challenging clinical situations. Below is a brief description of these conditions that may be helpful when identifying these patient subsets.
Diabetes. Individuals with diabetes typically have small, diffuse arteries, which often leads to peripheral vascular disease and poor circulation. These patients are also at a potential risk for infection.
Hypertension. Patients with hypertension are at risk for developing bleeding complications during sheath removal. Administration of anti-hypertensive medication may be required to maintain a stable blood pressure prior to sheath removal to prevent a potential hematoma.
Multiple procedures. Patients who have had multiple femoral approaches can be a challenge with subsequent procedures. Re-accessing the groin site is not only uncomfortable for the patient, but it can also be difficult for the operator to penetrate the subcutaneous layer due to scar tissue, which may cause the sheath to bend or kink.
Obesity. Accessing the artery of an obese patient can be a challenge. The position of the inguinal skin crease itself can be misleading due to the folds in the skin. It is essential to properly and comfortably position the patient with full view of the groin site to ensure an accurate puncture site.
Thin patients. The depth of the arteriotomy site is typically shallow, resulting in minimal subcutaneous tissue for secure sheath placement.
Atherosclerosis. Patients with extensive peripheral vascular disease have brittle or friable vessels that are not only difficult to access, but can also be at risk for distal embolization due to calcification.
Tortuous iliac artery. Requires careful insertion of the sheath to prevent a sheath-induced laceration. A longer sheath (15-25 cm) may be used to bypass the tortuosity in facilitating ease of insertion for angiographic or guiding catheters.
Steps in Accessing the Femoral Artery Site
Dating back to the 1950s, the modified Seldinger technique has allowed for the continuous expansion of the volume and variety of minimally invasive procedures for both diagnostic and interventional procedures. Today, this technique is still the most widely used technique in accessing the artery.
Operators will often use landmarks, such as the location of the inguinal skin crease, as a way to identify the puncture site. However, it is preferred to locate the puncture point in reference to the inguinal ligament, which runs from the anterior superior iliac spine to the pubic tubercle. This is especially true in patients with underlying conditions such as obesity where location sites can be misleading.3
Regardless of the patient’s specific consideration, adequate local anesthesia is essential for a successful catheterization. Inadequate anesthesia leads to poor patient cooperation and makes the time in the catheterization laboratory unpleasant for both patient and operator. Patients may also be given a mild intravenous sedative for relaxation.
By accurately identifying the proper access site, the operator will facilitate smoother vessel entry and effective compression to minimize local vascular complications.
Below are the steps required for a successful insertion.
Identify the landmark between the anterior superior iliac spine and the pubic tubercle along the inguinal ligament. Many times a sterile clamp is placed on top of the prepped patient while visualizing the location of the femoral head under fluoroscopy. This landmark will ensure proper alignment for needle and wire access targeting the middle of the femoral head. (It is important to note that in some areas of the United States, only physicians are permitted to utilize fluoroscopy.) Placement of the needle should be 1 to 2 cm below the inguinal ligament (2 finger breaths) while palpating the femoral artery pulse.
An 18 or 19 gauge needle is typically inserted at approximately 45° along the axis of the femoral artery as palpated by the two middle fingers of the left hand. It is important to remember that the true arteriotomy site (on top of the vessel wall) is approximately 2 cm superior to the external puncture site for a patient with a normal Body Mass Index. This reminder will facilitate proper hand and finger placement during manual compression post sheath removal.
You will note the pulsatile blood flow once you have accessed the artery. At this time, a 0.035- or 0.038-inch J-tip guidewire should be advanced carefully into the needle. A J-tip guidewire is used to prevent any internal trauma to the intimal wall of the vessel. The needle is removed while securely holding the guidewire in place with the left hand. As an optional step, an additional skin nick may be made at the puncture site to ensure ease of sheath insertion.
The sheath and dilator should have already been prepped with sterile heparinized saline. Begin to advance dilator and sheath over the wire until the entire length of the sheath has been inserted. It is important to remember to have a complete over-the-wire placement before inserting the tip of the dilator into the puncture site. When this is achieved, you will remove the wire and the dilator from the sheath. Should the sheath have a side arm, you will want to make sure that you are able to aspirate blood freely within the sheath; reflush the sheath again with heparinized saline.
You are now ready to begin your procedure.
Areas of Concern
If the artery is accessed above the inguinal ligament, the operator may not be able to adequately compress the arteriotomy site after sheath removal. A puncture of the artery at or above the inguinal ligament makes catheter advancement difficult and predisposes the patient to inadequate compression, hematoma formation, and/or retroperitoneal bleeding.
Puncture of the artery greater than 3 cm below the inguinal ligament increases the chance that the femoral artery will have divided into is profunda and superficial femoral branches. If the artery is accessed at or below the bifurcation of the common femoral artery, or if the superficial femoral artery was the site of puncture, the operator may have a difficult time achieving hemostasis during sheath removal due to lack of adequate ligament support during manual compression.3
Most procedures are performed with a sheath size ranging from 5-8 Fr. A smooth transition between the dilator and sheath will facilitate ease of insertion, thereby providing comfort to the patient and maintaining the integrity of the skin at the insertion site. The sheath must also be kink-resistant to tolerate multiple guidewire and catheter exchanges to sustain longer procedure times.
Timely and safe removal of the arterial sheath with minimal patient discomfort is an integral part of any diagnostic or interventional procedure. The presence of a sheath in a heavily anticoagulated patient that is receiving heparin or potent IIb/IIIa inhibitors (reteplase, abciximab and/or eptifibatide) predisposes perisheath hemorrhage, and local or retroperitoneal hematoma. Patients with clotting disorders risk having acute thrombus formation and possible distal embolization. While vascular complications will often present themselves in the form of thrombosis, embolus or infection, other complications can be quite common.3
Local Vascular Complications
Local complications at the sheath introduction site are among the most common problems seen after cardiac catheterization procedures. Specific problems include poorly controlled bleeding at the puncture site, vessel laceration, excessive anticoagulation, distal embolization and vessel thrombosis. Below are some complications that can occur.
Hematoma. Removing the sheath prior to proper hand positioning and timely compression can lead to formation of a hematoma. This is a collection of blood within the soft tissues of the upper thigh. If bleeding from the hematoma is controlled with manual compression, the hematoma will usually resolve within 1-2 weeks as the blood is reabsorbed from the soft tissues.
Retroperitoneal Hematoma (RPH). With RPH, the bleeding occurs inside the peritoneal cavity. Symptoms that may arise are abdominal pain, groin pain, back pain, diaphoresis, bradycardia or hypotension. Risk factors include female gender, low body surface area, double wall stick and high femoral artery puncture.3
Pseudoaneurysm. Sometimes referred to as a false aneurysm, pseudoaneurysms are common vascular abnormalities where a collection of blood begins to form within the intimal arterial wall. Generally evident within 12 hours of the procedure, the diagnosis of false aneurysm many not be evident for days or even weeks after the procedure. Symptoms can include groin pain or pulsatile mass.
Arterio-venous (AV) fistula. Bleeding from the arterial puncture may track into the adjacent venous puncture, forming an arteriovenous fistula and a continuous bruit. Many of these are small and resolve spontaneously. Surgical repair is required to fix enlarging fistulae before a hemodynamic compromise develops. AV fistula is often associated with a low groin puncture and can occur during manual compression. It is typically asymptomic and can be confirmed with a Doppler ultrasound.
Arterial Thrombosis. Consultation with a vascular surgeon is necessary in cases of paresthesia (an abnormal sensation of the skin, such as numbness), or where reduced distal pulses occur following catheterization. Predisposing factors for arterial thrombosis include a small vessel lumen, peripheral vascular disease, diabetes mellitus, and female gender.3
A Final Note
In all minimally invasive procedures where arterial access is required, it is essential to have a complete understanding of your patient and other special pre-existing conditions that may lead to complications. Taking certain precautions and ensuring proper access will help a laboratory team yield successful results.