Biomedical Engineering Reference
In-Depth Information
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Using the thumb, identify the pressure of the needle as it
goes through the surface fasciae; lead the needle to deep
tissues in the direction of the subclavian vein and the first
rib that lies under it.
If the selected vein is punctured successfully, remove the
syringe from the needle while keeping the needle's position
in the vein. Pass the guide wire through the cylindrical guid-
ing sheath into the needle and then further through the needle
to the vein. Remove the needle and put the dilator on the cor-
rectly positioned guide wire that routes caudally through the
superior vena cava. The dilator and the introducer are inserted
jointly through the guide wire to the vein. When the guide
wire is removed, the lead and the stylet are introduced into
the required position. After measurement of electric param-
eters, the lead is fixed. Tear the introducer apart to remove it.
In cases of a difficult venipuncture, it is necessary to intro-
duce two endocardial leads from the only successful veni-
puncture. In this case, leave the guide wire in the introducer
and remove only the dilator. During this procedure, use the
first venipuncture kit with a respectively bigger diameter. Do
not remove the guide wire, and insert the lead and the stylet
to the required position. To avoid blood loss and aeroembo-
lism, close the introducer mouth using a finger. After mea-
surements and fixation of the first lead, remove the first
introducer. Insert the second dilator and continue using the
same procedure as in the case just one lead implantation.
As the lead is implanted by means of the subclavian veni-
puncture, allow slack in the lead between the distal suture
sleeve and the venous entry site. This will help to minimize
flexing at the suture sleeve and interaction with the clavicle
and first rib region.
Fig. 12.1
Location of puncture needle entry [ 49 ] (© 2012 Boston
Scientific Corporation or its affiliates. All rights reserved. Used with
permission of Boston Scienti fi c Corporation)
When the lead is inserted using the subclavian venipunc-
ture method, a venipuncture kit and a subclavian introducer
are used. The kit contains a venipuncture needle, a syringe, a
hemostasis valve introducer, a dilator of the appropriate
diameter (in accordance with the lead diameter), and a guide
wire. When attempting to implant the lead via the subclavian
venipuncture, do not insert the lead under the medial one
third of the clavicle because the lead may be damaged. The
lead must enter the subclavian vein near the lateral border of
the first rib and it must avoid penetrating to the subclavius
muscle. Complying with this safety measure is important to
ensure that the lead is not damaged by the clavicle or by the
first rib. The lead inserted by percutaneous subclavian veni-
puncture must enter the subclavian vein, where it passes over
the first rib to avoid entrapment by the subclavius muscle or
ligamentous structures associated with the narrow costo-
clavicular region. So, it is suggested that the lead be inserted
near the lateral border of the first rib. The syringe must be
positioned directly above and parallel to the axillary vein to
reduce the risk that the needle will contact the axillary or
subclavian arteries or the brachial plexus.
The instructions below explain how to identify the venous
entry site and define the course of the needle toward the sub-
clavian vein where it crosses the first rib.
According to Fig.
12.1.1 Positioning the Lead in the Right Atrium
With the straight stylet in the lead, advance the lead trans-
venously into the right atrium. When the lead is far enough
within the right atrium, introduce the
J
-shaped stylet or a
bended straight stylet. Carefully pull the lead and stylet
together at the venous entry site to check for contact between
the electrode tip and endocardium. A part of the lead sterile
package might include various
J
-shaped stylets. A longer
action radius is suitable for most patients; bending a smaller
stylet might be suitable for patients with a smaller atrium
who underwent heart surgery. The most suitable position of
the electrode tip is in the right atrial appendage (right auricle)
opposite the endocardium (see Fig.
12.2
). Use the fl uoroscopic
anteroposterior projection to check whether the electrode tip
is directed medially toward the left atrium.
After the lead tip is fixed to the heart wall, check for the
proper motion of the lead. It is necessary to ensure adequate
slack of the lead in the atrium that helps to decrease the risk
of dislodging the lead. As the patient exhales, the
J
-shaped
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12.1
, identify the sternal angle (St) and
coracoid process (Cp).
Visually draw a line between the St and Cp points and
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divide this segment into thirds. The needle should pierce
the skin at the junction of the middle and lateral thirds,
directly above the axillary vein.
Place your index finger on the junction of the medial and
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middle thirds (point V), beneath which point the subcla-
vian vein should be located. Compress a thumb against
the index finger and project 1 or 2 cm below the clavicle
to protect the subclavius muscle from the needle.
