PREOPERATIVE PLANNING

Preoperative planning is the cardinal principle of surgical treatment. Most poor outcomes can be avoided by adhering to this principle alone. Planning should include correlation of the size, extent, and involvement of structures with physical examination and imaging. Imaging modalities include plain radiographs, ultrasonography, MRIs, and angiography. Before surgery is performed on complex, fast-flow lesions, a step-by-step plan of resection, including the approach and extent of resection, must be determined and followed. Despite imaging, the extension of some anomalies may not be completely delineated, and intraoperative decision-making may be required after the true extent becomes visible. Despite this, the surgeon must abide (as much as possible) by the initial surgical plan; straying from the plan may lead to a violation of uninvolved areas, an inadvertent injury to neurovascular structures, a waste of precious tourniquet time, and an incomplete excision. For complex lesions, we have found it helpful to print the angiogram and label the nidus, shunts, and all large branches within that portion of the lesion to be excised. These scans should be displayed in the operating room for easy reference during the procedure. Other preparatory steps for fast-flow lesions include central venous and peripheral arterial monitoring, availability of warmers and blood products for transfusion, and ICU monitoring after surgery.

PLACEMENT OF INCISIONS

Placement of incisions is important, particularly in children. When planning an incision, the surgeon should consider exposure, blood supply, function, aesthetics, and future surgery. Incisions should be long enough to provide full exposure of the entire lesion. Small incisions provide no surgical advantage and risk injury to important structures, especially in the hand. In the digits, a high midaxial incision is preferred, because it provides excellent dorsal and palmar exposure, can be used again, and is typically well hidden. Dorsal longitudinal hand and digital incisions are avoided, if possible, because they provide less exposure and are more conspicuous. Palmar incisions can lead to contracture if poorly planned; zigzag incisions and those that use normal skin creases are recommended.

If multiple debulking procedures are contemplated in the upper arm or forearm, each incision should be planned carefully to avoid unnecessary scarring near neurovascular structures. The medial surface of the arm, elbow, and forearm is the least conspicuous. Scars in the web spaces or along eponychial and/or paronychial folds will contract and are likely to become problematic.

Ironically, vascular insufficiency can exist in the presence of a vascular anomaly, especially fast-flow types; thus blood supply should be carefully considered during planning of incisions. The dorsum of the hand has an axial blood supply above the overlying fascia, whereas the palm of the hand receives perforators from palmar arterial branches. Accordingly, large flaps can be developed safely in the dorsum, but similar flaps are prone to ischemia in the palm. To avoid digital vascular compromise, only one half of a digit should be dissected at a time. When a critical arterial segment to a digit or the hand is removed, this segment should be reconstructed with a vein graft so that at least one digital artery is preserved per digit, and one major artery supplies the hand with a functionally intact palmar arch.

DISSECTION IN A BLOODLESS FIELD

Dissection in a bloodless field is critical for identification of important structures and delineation of the vascular lesion. Accordingly, a pneumatic tourniquet is essential for all but the simplest excisions. Limb exsanguination should be thorough before tourniquet inflation. If bleeding occurs in the wound within 5 to 10 minutes of tourniquet inflation, the arm should be reelevated and the process repeated. In small children we use the elastic Esmarch wrap as the tourniquet secured at the midhumeral level. Dissection of VMs, lymphaticovenous malformations (LVMs), and arteriovenous malformations (AVMs) with arteriovenous fistulas is most vulnerable to blood staining, whereas LMs are more forgiving. A blood-stained field within any dissection will decrease visibility, obliterate fascial planes, and set the stage for potential injury to important structures.

With a chest wall LM and capillary-LVM excisions or brachial plexus explorations, the tourniquet cannot be used. During these long procedures, blood loss can be insidious, especially in small children. Thus a premium is placed on meticulous hemostasis, which is best accomplished by careful dissection and preemptive ligation or clipping of vessels before they are cut. To further minimize surgical blood loss and blood staining, four types of cautery devices are used selectively: the monopolar cautery, the bipolar microsurgical cautery, the battery-operated handheld ophthalmic cautery, and the Aquamantys system (radiofrequency energy with saline coolant). Each device has a specific use. The monopolar cautery is used for subcutaneous dissection, the bipolar is used for small vessels, and the ophthalmic cautery is used for developing surgical planes, especially within muscles, which tend to fasciculate with the monopolar cautery. The Aquamantys system coagulates larger vessels and high venous pressure/variceal types of bleeding commonly encountered during excision of VMs. Tissue sealants have been a useful adjunct at the end of a procedure after the tourniquet is deflated. Excision of fast-flow lesions of the chest and axilla is a dreaded (but not impossible) procedure and accomplished with the aid of intraarterial balloon catheters, hypothermia, hypotensive anesthesia, cell savers, adequate blood and fluid resuscitation, and experienced anesthesiologists and cardiovascular surgeons.