Emergency Vascular Surgery A Practical Guide - part 9

160 Chapter 13 Acute Venous Problems incidence varies with the population studied and increases with age. Hospital-based studies present a larger proportion of pulmonary embolism (PE), whereas community cohorts have more thrombo-sis patients. Manifestations range from a superfi-cial thrombophlebitis or a minor deep venous thrombosis (DVT) that produces only minute symptoms to a DVT with massive embolism to the lungs, threatening the patient’s life. While open surgical treatment of venous thromboembolic dis-ease is rarely indicated, it is helpful to have basic knowledge about diagnosis, pathogenesis, and anticoagulation treatment. This is important for differential diagnosis and for the few instances when emergency endovascular or open surgical treatment is indicated. This chapter will also de-scribe the technique for surgical and endovascular treatment of acute DVT. 13.2.2 Pathogenesis When DVT occurs, clots have usually formed in the small deep veins in the calf. Patients afflicted have hypercoagulative disorders, are taking medi-cations that affect clotting that make them sus-ceptible to venous thrombosis, has malignancy or has been immobilized for a larger period. The clot causes a local inflammation in the venous wall and adjacent tissue that may make the calf tender. Because the small veins in the calf are paired, the clot does not cause significant venous obstruction or distal edema. Flow in the obstructed vein will decrease, however, which increases the risk for continuing clot formation. The clot will then grow in a proximal direction and continue to obstruct more veins. Also at this stage distal edema is quite uncommon because collateral flow is extensive in the legs, and significant swelling does not occur until the common femoral vein is obstructed. At this level the outflow from the deep femoral, su-perficial, and great saphenous vein is affected. Continued obstruction, causing near occlusion of all the main veins in the leg and pelvis, can lead to a dreaded condition called phlegmasia cerulea do-lens (discussed later). Any time during this pro-cess there is also a substantial risk that clots will dislodge from the leg veins, follow the blood flow to the lungs, and cause PE. Primary iliac vein thrombosis occurs most commonly on the left side where a stenosis fre-quently is a predisposing factor. 13.3 Clinical Presentation Patients with DVT experience pain and leg swell-ing that often is worse when standing or walking. Some patients also feel warmth and notice that the leg is red. Patients with caval obstruction have bilateral symptoms. These examples constitute the classic symptoms of DVT, but many patients do not have any symptoms at all and present with PE only. Signs of this condition include shortness of breath and chest pain that may be worsened by deep breaths. Occasionally, patients also report that they have been coughing up phlegm that may be tinged with blood. Patients with phlegmasia cerulea dolens have similar but more severe symptoms. Discoloration is often pronounced. Pedal pulses are usually ab-sent, and the leg is very tender. Foot gangrene is also noted occasionally. It may therefore be mis-taken for arterial embolism, but misdiagnosis can be avoided by remembering that acute arterial occlusion does not cause edema. Physical examination is only 30% accurate for DVT and a poor way to establish the diagnosis. The most common finding, however, is localized calf tenderness. Homan’s sign – pain when dorsi-flexing the foot with the knee extended – is nei-ther sensitive nor specific and should probably not be used. Other examination findings are visible superficial collateral veins, pitting edema, and swelling of the entire leg. To be significant, the lat-ter should expand the calf circumference by more than 3 cm compared with the other leg. Patients with primary iliac vein thrombosis may present with abdominal pain in the lower quadrant, tenderness over the vascular bundle in the groin and general swelling of the leg. Patients with upper limb thrombosis have sim-ilar symptoms; the most common are arm swell-ing and discoloration or pain. Scoring systems combining clinical findings and medical history have been proposed to in-crease accuracy of the examination. If the exami-nation is positive for more than three of the signs and symptoms described above, up to 75% of the 13.5 Management and Treatment 161 patients have evidence of DVT as diagnosed by duplex examination. 13.4 Diagnostics All patients, including those considered to have only small risk to be suffering from DVT and those having arm symptoms, should undergo duplex scanning or perhaps phlebography. The duplex ex-amination includes visualization of the veins, clots, blood flow, and vein compressibility. The latter is considered a direct test of DVT because a vein with clot cannot be compressed, whereas the walls of a healthy vein are very easy to squeeze together by pressure with the probe. Lack of blood flow variation with breathing is another sign suggesting DVT on duplex examination. Phlebog-raphy includes cannulating a superficial foot vein and injecting contrast during fluoroscopy to enable visualization of thrombosed veins. This method was the standard diagnostic procedure before duplex appeared as the primary choice for establishing the DVT diagnosis. Today it is used mostly when duplex is unavailable in the hospital or when it is unable to identify the deep leg veins. Another test useful for DVT diagnosis is deter-mining the concentration of the fibrin degrada-tion product D-dimer in the blood. This test has a sensitivity for DVT of 90% or greater as well as a negative predictive value of 90% or greater by most studies. Accordingly, a negative D-dimer level (the cut-off level depends on the type of assay used) in a symptomatic patient with a clinically suspected diagnosis nearly provides exclusion of DVT. There-fore, it is suitable as a screening test before further work-up when the diagnosis is not obvious. tals this means starting with duplex scanning to establish the diagnosis. If signs of DVT are pres-ent, it is important to elucidate the extent of thrombosis during the examination. This infor-mation is useful in the management process be-cause some patients with femoral vein, iliac vein, or cava thrombosis may need thrombolysis or even a cava filter. When the DVT diagnosis is con-firmed, baseline blood coagulation parameters are obtained, and low molecular weight heparin treat-ment is initiated. It is also important to exclude other diagnoses that could contribute to the thrombosis formation. For example, clinical indi-cations of an intraabdominal malignancy could be confirmed or eliminated by computed tomogra-phy (CT). Both inpatient and outpatient protocols can then be used for the continued treatment of the patients. (No further recommendations will be given on the medical management of DVT here because this book is intended to focus on vascular surgical treatment.) Few diagnosed patients are candidates for urgent surgical or endovascular treatment, but the most common situations when it can be con-sidered are listed in Table 13.2. Patients with upper limb thrombosis may also benefit from urgent thrombolysis. The same clinical findings listed in the table are also applicable in patients with duplex-verified axillary or subclavian vein throm-bosis. If D-dimer is positive and pulmonary symp-toms are prominent in the medical history (or the Table13.2. Clinical findings indicating that open sur-gical or endovascular treatment should be considered in patients with duplex-verified thrombosis into femo-ral and/or iliac veins 13.5 Management and Treatment 13.5.1 In the Emergency Department Patients who complain of unilateral limb swelling and pain should be suspected to have DVT and have a blood sample drawn for measuring D-di-mer. A negative test excludes DVT or PE as the primary diagnosis. Patients with a positive D-di-mer may suffer from a venous thromboembolic disease and need further work-up. In most hospi- Clinical findings Young age Duration of symptoms <10 days Pronounced symptoms Contraindications to heparin treatment Phlegmasia cerulea dolens Free-floating thrombus in vena cava Treatment type(s) Thrombolysis Thrombolysis Thrombolysis Cava filter, thrombectomy Thrombolysis, thrombectomy, fasciotomy Cava filter 162 Chapter 13 Acute Venous Problems patient has chest pain or hemoptysis), a CT scan is added to the duplex and laboratory work-up to re-veal signs of PE. Furthermore, if PE is confirmed, evaluation of the heart function by echocardiogra-phy is also valuable. Such patients should also re-ceive oxygen. It must be kept in mind that patients with PE may have a negative D-dimer. If suspicion is strong, the work-up should proceed regardless of the outcome of this test. Urgent thrombolysis may be indicated in patients with massive PE ob-structing more than 50% of the vasculature. Pul-monary edema and hypotension due to right ven-tricular failure are consequences of this, and the only way to save such patients may be to remove as much of the obstruction as possible. 13.5.2 Endovascular Treatment The purpose of thrombolytic therapy is to reduce the long-term consequences of extensive, particu-larly caval and iliac DVT. Supposedly it restores patency and preserves valve function but long-term randomized studies comparing this therapy with standard anticoagulation have not been car-ried out. It may also reveal obstructions contribut-ing to clot formation. Such stenotic segments may be treated by stenting. Thrombolytic therapy achieves more rapid clot resolution but does not significantly reduce mortality or the risk of recur-rent PE in hemodynamically stable patients. It is also associated with an increased incidence of ma-jor hemorrhage compared with heparin therapy alone. The main contraindications to thromboly-sis are listed in Chapter 10 (p. 128). Therapy should be administered locally by catheter-directed infusion of the lytic agent into the clot. Ipsilateral or contralateral groin access is commonly used. The latter reduces bleeding com-plications and decreases the risk associated with transversing the thrombus. Thrombus passage in-creases the risk for clot dislodgement and PE. The ipsilateral approach avoids transversing intact valves, but it may be more difficult to puncture and catheterize the groin vein if it is occluded. Du-plex-guided puncture could then be tried. Placing a catheter in the superficial femoral or popliteal veins may be impossible if the valves are intact. A jugular venous catheterization can be used if the clot involves the vena cava. It is common to use a side-hole catheter with its tip placed in the clot. a b Fig.13.1. Thrombolysis of iliac vein thrombosis before (a) and after therapy (b) When the venous system is catheterized, venogra-phy is performed to localize and determine the distribution of the thrombosis. Treatment proto-cols vary extensively. The first dose of tPA is often infused for 30 min, then the venography is repeat-ed. If more lysis is needed the infusion is contin-ued for 24 h or more. During this time period the result is checked repeatedly, depending on treat-ment progress. The bolus injection mentioned is not used in some protocols. An example of a veno-gram is shown in Fig. 13.1. 13.5 Management and Treatment 163 13.5.3 Operation Historically, surgical thrombectomy has been lib-erally used in patients with iliofemoral thrombo-sis to reduce the risk of postphlebitic syndrome development. Although several patient series have presented good results after thrombectomy, ran-domized controlled trials data is less favorable. One study reported a similar long-term frequency of postphlebitic syndrome when comparing the procedure with low molecular weight heparin therapy, while others found better preservation of valves and fewer problems after surgery. Consid-ering the general surgical risk and postoperative complications such as groin infection and bleed-ing, it is rarely indicated to perform surgical venous thrombectomy today. It is used mostly in patients with extensive venous thrombosis who have contraindications for anticoagulation and lytic therapy. Another indication that remains is thrombus extraction in phlegmasia cerulea do-lens. The technique of venous thrombectomy is described in the Technical Tips box but can be quite difficult to perform if the experience of vascular surgery is limited. 13.5.4 Phlegmasia Cerulea Dolens This serious form of DVT is, as already mentioned, characterized by massive thigh and calf edema and a cold, mottled foot. The risk of massive PE is high, even for patients receiving anticoagulation therapy. Phlegmasia cerulea dolens often indicates occult malignancy which must be excluded in every patient. Treatment follows the principles given for DVT as outlined above, with the addition of fasciotomy when the arterial component is prominent. Throm-bolysis is the primary choice when the arterial perfusion is rendered adequate – palpable pulses in the ankle arteries or good skin perfusion in the foot. If the patient lacks foot pulses, surgical thrombectomy is a better strategy because it is a quicker way to reduce clot burden and obstruc-tion. Long-term venous function is of minor im-portance at this stage. When the arterial function is compromised, fasciotomy should follow the sur-gical thrombectomy For some patients, amputa-tion is the only option. TECHNICAL TIPS Venous Thrombectomy Preferably, general anesthesia is used and the pa-tient is given an antibiotic that covers common wound infection bacteria. A groin incision is per-formed right over the common femoral vein, which is extended distally over the superficial femoral vein. These two veins and their branches are exposed and banded. The patient is given in-travenous heparin, and a transverse venotomy is performed in the common femoral vein. The an-esthesiologist is then asked to adjust the ventila-tion to a high positive end pressure to minimize the risk of PE, while a #7 or #8 Fogarty catheter is passed proximally into the vena cava and as much of the clot as possible is extracted. This preventive measure is insufficient if the risk for PE is high. If the thrombus protrudes into or involves the vena cava, cava filter insertion should precede surgery. A balloon occluding the vena cava from the con- tralateral groin could also be used, especially if the thrombus is free floating but located only in the iliac vein. Next, a rubber bandage is tightly ap-plied around the entire leg from the foot to the wound to empty all distal veins from thrombus. Distal thrombectomy can also be done but is of-ten difficult because the valves make distal pas-sage of the Fogarty catheter impossible. Finally, a continuous 5-0 suture closes the venotomy, and an arteriovenous fistula is created. This is achieved by using a branch from the greater saphenous vein and performing an anastomosis between its end and the common femoral artery. The reason for this is that the patency of the iliac vein is con-sidered to be better if a higher flow is achieved. It does require exposure of the artery and its branch-es. After control of any remaining bleeding, the wound is closed. 164 Chapter 13 Acute Venous Problems 13.5.5 Vena Cava Filter Placement Indications for vena cava filter placement include the following: Recurrent PE despite full anticoagulation Proximal DVT and contraindications to full anticoagulation Proximal DVT and major bleeding while on full anticoagulation Progression of iliofemoral clot despite antico-agulation Large free-floating thrombus in the iliac vein or inferior vena cava Massive PE in which recurrent emboli may prove fatal Venous thrombectomy (during or after surgery) Several types of filters are available on the market, and temporary filters can be used when perma-nent placement is not necessary; one such situa-tion is the last one in the list above. The complica-tion rate after filter placement is low. Occasionally the filter may be dislodged into the right atrium, but insertion site bleeding is more common. The filter can be inserted by either a jugular or femoral approach. The former is preferred if the CT has revealed extensive thrombus in the inferior vena cava. The method for filter placement via the femoral vein is briefly described in the Technical Tips box. TECHNICAL TIPS Vena Cava Filter Placement Before the procedure it is sometimes necessary to make sure that the iliac veins on the access side and the inferior vena cava are free of thrombus. This is done by cannulating the femoral vein using the Seldinger technique and inserting a guide wire and an introducer sheath. A venogram is obtained by manual injection of contrast. Diame-ter estimations and better visualization of the vena cava and the renal vein location can be 13.5.6 Postoperative Treatment After thrombolysis or thrombectomy, patients should keep their leg or arm elevated and com-pression stockings are applied. They should be used day and night for at least 2 weeks postopera-tively. Intermittent compression devices increase venous blood flow and probably improve patency after thrombolysis and thrombectomy. For the latter, the benefit is supported by clinical stud-ies. Patients should also receive long-term antico-agulation, initially with low molecular weight heparin that is substituted for coumadin for at least 6 months. If not investigated previously, un-derlying coagulation disorders should be consid-ered because this would influence the length and type of treatment achieved by introducing a pigtail catheter placed higher up. For filter placement, a larger sheath, at least 12-French, is placed over a stiff guide wire approximately to the level where the filter is to be placed. The preloaded filter catheter is advanced to the implant site and released during fluoro-scopic monitoring. After the catheter is withdrawn a venogram completes the procedure. 13.6 Results and Outcome There are several studies in the literature compar-ing thrombolysis and anticoagulation for acute DVT, and meta-analyses suggest that the former is more effective for clot lysis and venous patency. Furthermore, significantly fewer patients appear to end up with postthrombotic syndrome when treated with thrombolysis as compared with anti-coagulation. Accordingly, many patients with acute iliofemoral DVT should be considered for thrombolysis. As suspected, however, more bleed-ing complications occur with this treatment strat-egy, so careful selection of patients is important. Also, surgical thrombectomy appears to be more effective, than anticoagulation alone. In one study this strategy was able to preserve at least half of the ... - tailieumienphi.vn