Recap : Anatomical considerations before making an pocket : See here
Planning of Incision
The pacemaker pulse generator (the ‘Device’) is usually placed in the pectoral region, in a pocket created under skin.The floor of the pocket is the fascia covering the pectoralis major muscle (part of the clavipectoral fascia) and the roof of the pocket is formed by deep layer of the deep fascia. This pocket is also referred to as the “Pre-Pectoral Pocket” as the pocket lies on the pectoralis major muscle. It is important to understand and identify these fascial layers as they are the principle support of the device pocket. Proper closure of the fascial layers helps in excellent healing with good long-term outcome and device stability.
The device can be also placed deep to the pectoral muscle (sub pectoral pocket) and this is explained later. The vast majority of pacemakers can be placed in the pre-pectoral position with excellent cosmetic outcome. Sub pectoral pocket creation is technically challenging, but may be required when the device – tissue ratio is larger for example when placing an ICD in a child. (there are other locations such as sub-mammary, abdominal etc.. but that’s a separate topic)
There are two ways of making the incision
- Incision made parallel to the clavicle
- Incision made in a curvilinear cut following the skin crease.
My original technique of incision is was usually made parallel mid part of the clavicle, 2 finger breadths below the clavicle and is about 5 cm in length, incorporating the guidewire at its lateral end. If the puncture was very medial, the incision may be done to have the wire in its mid part rather than lateral end.
The incision is usually centered slightly medial to the center of the delto-pectoral groove – but the length and deciding the ends of the cut takes some practice. If the incision too infero-lateral (i.e. away from the vascular entry target site) you may have difficult in reaching the correct plane with the puncture needle. In such cases a slight medial extension of the medial edge may be necessary to avoid struggling in finding the vein. Even if the incision is too long, scarring is minimal here – so its unlikely to be of a cosmetic concern.
In women, it may appropriate to avoid being too medial as female dress patterns may reveal the scar. Extreme laterality also must be avoided as the device has minimal support and may migrate or it may interact with the shoulder joint movement in a thin patient.
Once the incision line has been infiltrated with local anaesthetic, further infiltration along the pocket margins (medial and lateral) are done to provide additional blockade to the future pocket. About 2-3 parallel injections would suffice (see video below) requiring about 15 ml 1% solution. Slow but firm massaging the infiltration zone helps deeper dispersion and 1 minute is allowed for the anesthetic to act. Keep about 5 – 10 ml available to be injected through the pocket at a latter stage (Click here for a Detailed discussion on Local Anaesthesia)
VIDEO : Recap of Local Anaesthesia before Puncture : About 10 ml of 1% lignocaine is injected under skin in a triangular area in which the base is the clavicle and apex is just distal to the skin puncture side. Gentle massaging of the area helps dispersion of anaesthetic. Note : Sedation should be in place before this is performed.
Before Skin Incision
VIDEO: Local Anaesthesia to Skin Incision and Pocket : Local is injected along the future incision line and along the lateral borders of the pocket. Additional doses may be injected along middle of the future pocket to ensure complete anaesthesia of the pocket.
Incision and Dissection
The incision is done as planned using a 22 or 11 G surgical blade with a single stroke. As far as possible the initial skin incision should be done with a single stroke without damaging skin edges with multiple strokes which may lead to scarring.
- The requirement for shallow cuts is mandatory when doing re-operations (e. g. box changes, lead revisions ) as one never knows how close the underlying lead / device is to the skin.
- In thin patients, attempting a deep single cut may damage the fascial envelope of the pectoralis major muscle leading to troublesome bleeding (oozing) from the raw edge of the muscle.
The dermal separation has no outcome on the final cosmetic result as long as the epidermal separation was neat.
Once the skin incision has been done, if a large pocket is anticipated (e. g. ICD) additional local anesthetic drug is injected to the depth of the pocket. Its not necessary to inject along the whole line of incision: deep and generous injections along the lateral and medial borders of the future pocket would be sufficient as dictated by anatomic principles. Indiscriminate injection to the pocket should be avoided as this distorts pocket tissue planes and predisposes to local anaesthetic overdose.
Creation of Pocket : Essential Points
Once the pocket has been created, any bleeding points should be controlled using either diathermy or suture ligation. Indiscriminate diathermy should be avoided as charring and coagulum formation in the pocket is undesirable. The author does not use diathermy to dissect tissues. (However this may change in the future with the availability of the PeakPlasma Blade)
Once the incision has been made, dissection of the fascial layers is done to reach the pectoralis muscle surface. Care should be taken not to breach the fasical envelope of the muscle (clavipectoral fascia) as troublesome bleeding can occur if the muscle substance is cut. To dissect down, the author prefers using a sharp fine scissor to cut in layer by layer while holding the anterior flap taut with a hook. This technique is especially useful if there is no assistant. The absolute requirement is a sharp pair of scissors !
Upon visualizing the muscle, dissection now extended inferior to create a small gap between the muscle and the anterior pocket flap. A finger then inserted into this gap and blunt sweeping is done to separate the anterior flap further down from the muscle thus creating the pocket space.
Upon visualizing the muscle, dissection now extended inferior to create a small gap between the muscle and the anterior pocket flap. A finger then inserted into this gap and blunt sweeping is done to separate the anterior flap further down from the muscle thus creating the pocket space. If one is in the correct plane (i.e. in the loose deeper layer of the deep fascia), this finger dissection would be easy and bloodless. This plane is quite thick and readily achieved in women but may be difficult in thin men. If the pocket is made on the correct plane, one would see the pectoralis muscle (covered by it’s fascial envelope) lying on the floor of the pocket.
Although it may sound unkind, pain on injecting anaesthetic deep into the pocket suggests that there are sensitive bits remaining which need to be anaesthetized and is a marker of good anaestheisa during further deepening of the pocket. If not sedated, I always warn the patient when I am injecting deep into the pocket as its not usual to find a patch of pocket un-anaesthetized.
Tip : The most uncomfortable part of a pacemaker implantation is the creation of the pocket. That’s why I advocate a good bolus of short acting sedation at the beginning – just sufficient to cover the pocket creation. Experience will tell you despite the most meticulous anaestheisa, patients feel pain when deepening the pocket – especially when large devices like ICDs are implanted. It makes much more comfortable for the patient and makes the operator’s life much easier by having sedation on board during the pocket creation (more information here)
The final step in creating the pocket is to separate the guide-wire from the skin edge, well up the floor of the pocket. (i.e. the guide-wire should be coming out from the pocket floor rather than the incision edge. This is a critical step to ensure that the future lead is well away from the incision margin. (Author has seen several cases of lead sleeve erosion resulting from inadequate depth of lead from the skin incision)
Creation of Pocket : Guided Videos (Please watch in HD and pause when necessary to view captions)
Once the guide-wire is made to come out of the floor of the pocket one may proceed to create additional punctures for additional wires if a multilead device is planned or proceed to insertion of sheath for single lead device. If muliple leads are necessary, additional axillary vein punctures are done through the pocket following the existing wire keeping few millimeters gap in-between the wires. Another method is to double wire (piggy back technique) the existing wire and insert additional wires – all of this is explained here in the section of multi-lead device vascular access.
Before proceeding for sheath insertion, a dry gauze swab is kept deep within the pocket to soak up delayed bleeders. It is imperative that the insertion of this swab is coordinated with the assisting nurse and ensure that it is removed before the device is inserted to the pocket. However trivial it seems, in obese patients and with deep pockets, the swab can be easily forgotten and left inside !!