Vascular Disorders of the Hand

Etiology of Ischemia

Hand ischemia can result from iatrogenic injury, trauma, or vascular disease. Fortunately, iatrogenic injury is unusual; however, the potential to negatively affect flow to the hand is present in many procedures. An Allen test should be performed routinely prior to any intervention involving the radial artery ( Fig. 60.2 ). Radial artery puncture is a commonly used procedure for harvesting blood to measure gases, and indwelling catheters in the radial artery are commonplace for the monitoring of unstable patients during and after surgery. Although isolated radial artery puncture is exceedingly unlikely to cause ischemia in the hand, indwelling catheters are known to cause permanent ischemic complications in approximately 0.09% of patients.

In the group of patients who develop ischemic problems, studies have shown that surgical intervention is not universally successful, probably due to the severity of vascular disease in the radial artery and the effects of distal embolization from the site of injury ^, ( Fig. 60.3 ). Depending on the patients’ underlying problems, it may be best to manage them with anticoagulation, regional nerve blocks, and possibly intraarterial thrombolytics. The increasing trend toward management of vascular problems with endovascular techniques has led to renewed interest in peripheral artery access, with the radial artery offering a relatively easy way into the arterial system. While early reports minimize the complications of this approach, recent reports have shown some utility in reversing hand ischemia via endovascular techniques. Gandini has reported success using endovascular balloons and stents in the distal arteries of the forearm, but he emphasizes that the endovascular instruments utilized should be those used in cardiac vascular intervention due to the small size of the vessels in the distal forearm.

Currently, the radial artery is often harvested for cardiac revascularization and radial forearm flap reconstruction, which also can lead to hand ischemia. The standard to use to avoid problems is the preoperative Allen test, as noted earlier. Despite the routine use of it, ischemic episodes have been reported after radial artery harvest. This problem can be managed successfully, however, by performing a bypass with the autologous vein to replace the harvested radial artery.

Another iatrogenic cause of ischemia is vascular access in the upper extremity for hemodialysis. This happens in a range of 2% to 5% after a vascular access procedure and can be due to distal embolization or a “steal” phenomenon; in this case, the majority of the arterial flow is diverted across the fistula, leading to ischemia in the distal hand. Often the fistula will have to be banded or even ligated to decrease the shunting of blood from the hand; however, vascular surgeons are usually unwilling to ligate these because of the difficulties of long-term access in dialysis patients. Another option is the so-called distal revascularization interval ligation (DRIL) procedure.

In this operation, a vein graft is sewn into the artery above the site of the fistula, and the bypass is anastomosed to the distal artery at a level beyond it. The native artery is then ligated just distal to the fistula. This theoretically leads to the hand getting the majority of flow rather than the shunt and is effective in many patients. Diabetic patients on dialysis present other difficulties in that they often develop worsening arteriosclerosis of the upper extremity’s vessels and ongoing ischemia; this will be discussed later in this chapter.

The other cause of ischemia of the hand is trauma, which can be either an open or a closed injury to forearm and hand vessels. The classic case of a closed injury to the hand’s arterial supply is in supracondylar fractures in children. In these patients, displacement of the fracture leads to injury and spasm of the brachial artery, which if not recognized can lead to a compartment syndrome and ultimately a Volkmann ischemic contracture of the flexor muscles. Another fairly common type of closed vascular injury unique to the hand is ulnar artery thrombosis, or “hypothenar hammer syndrome.” This injury occurs with closed trauma to the palm of the hand, often when it is used as a hammer or when the hypothenar area suffers a blow. Open injuries, whether by firearms or by lacerations, are particularly common in the forearm and hand. As noted earlier, injury to a single vessel rarely causes acute ischemia but undiagnosed injuries can lead to aneurysm formation and potential distal embolization.

The final cause of ischemia in the hand is intrinsic vascular disease, which can be either arteriosclerotic or vasospastic. They can be seen in combination, which is known as “vasoocclusive” disease. Although Buerger disease has historically been a major cause of arteriosclerotic disease in the upper extremity, in today’s world the most common cause is a combination of diabetes and renal insufficiency. This combination of disease processes leads to accelerated occlusive vascular disease in the upper and lower extremities, and it is not uncommon to see patients with bilateral lower-limb amputations appear with critical ischemia of the hand. Likewise, patients with collagen vascular disease (i.e., scleroderma primarily) suffer from vasculitis and vasospastic disease, which can lead to vasoocclusive disease. The patients can present difficult management issues, and surgical intervention, while helpful, often does not provide a long-term solution.

Evaluation

As with any problem, patients first need to provide a thorough history and undergo a physical examination. Obtaining a medical history, with particular attention to documented diabetes and/or collagen vascular disease, is very important. Obviously, a habit of smoking will have an impact as well. Medical management of the diseases with pharmacologic agents may mitigate some of the symptoms, particularly in those patients with Raynaud disease. The physical examination should pay close attention to the appearance of the hands and the color of the fingers, looking for evidence of ischemia and/or gangrene or ulceration. Likewise, the warmth of the fingers is important, and sensation also plays a role, with the potential for sympathetic overactivity in the presence of nerve compression.

The pulses at the elbow and wrist should be felt, and I feel that Doppler ultrasound plays a very important role in the examination of the patient with a vascular disorder. An Allen test can be done, as described before; however, performing a similar exam with the pencil Doppler may yield much more information. The arch is located with the Doppler, and the radial and ulnar arteries are compressed sequentially at the wrist. The Doppler can be moved over the arch as necessary to follow the signal, listening for a change in character or flow. This technique can almost always diagnose the site of arterial occlusion if performed carefully. Likewise, an arterial signal should be heard with the Doppler placed on the pulp of the finger; if it is not, there is a significant problem with flow to that finger.

It should be noted, however, that the presence of an audible Doppler arterial signal in one of the wrist’s vessels is not an indication of adequate nutritional flow to the hand. By using this simple technique in the office, the surgeon usually can diagnose where the occlusion is; however, this information is not adequate for planning a surgical procedure. For this I prefer using computed tomography angiography (CTA) or arteriography—the latter if fine detail of the hand’s vessels is needed ( Fig. 60.4 ).

Others prefer a magnetic resonance angiography (MRA), but I have found that the detail in many of these images is inadequate in terms of knowing exactly where and how significant the problem is. The gold standard, however, remains digital subtraction angiography (DSA). Surgeons must view the vascular studies themselves because the radiologist or vascular specialist may or may not see the lesion. A familiarity with the upper extremity’s normal and variant anatomy is essential; however, surgeons who are dealing with vascular problems must evaluate every vascular study, both to review the anatomy and to identify the problem ( Fig. 60.5 ).

There are a number of other types of studies that can be done to aid in the diagnosis of vascular problems in the hand. Color-flow ultrasonography can show real-time flow and be used to evaluate an anastomosis, but it is of primary use in the venous system. A commonly performed test to evaluate vasospasm is cold stress testing, which gives a measure of the vascular system’s ability to recover from exposure to cold. In this test, digital temperature is measured at baseline and the hand is then placed in cold water (5° to 8°C) for 5 minutes. Thermistor probes (or laser Doppler) are used to measure the time required for digital rewarming to baseline. A prolonged rewarming response is often seen in women and can be diagnostic of Raynaud’s. Likewise, smokers often have a delayed rewarming response.

The digital–brachial index, which is the ratio of the blood pressure as measured in the brachial artery and the finger, can be measured with small blood pressure cuffs. This is similar to the ankle–brachial index, and in the upper extremity any value below 0.7 is felt to designate a significant occlusive problem somewhere in the forearm or hand. Blood flow in the capillary bed can be measured by laser Doppler flowmetry, which can give a quantitative measurement of blood flow at skin level. This can be a useful tool to evaluate the results of treatments, particularly for vasospastic problems; however, this equipment is quite expensive and not available to most practitioners.

Similarly, nail fold capillaroscopy shows morphology and flow at the capillary level but is not of practical use for most surgeons. Many of these sophisticated tests are difficult for the practicing surgeon to perform and do not add much, in my opinion, to decision making in terms of patient management. They, however, can be useful in determining the quality of the outcomes of management.

Management

Management of vascular injury or insufficiency in the hand may involve techniques ranging from ligation of the injured vessel to periarterial sympathectomy to complex vein or arterial grafting. Which technique is employed depends on the level of the lesion as well as the cause of the problem. The various techniques used to treat the major causes of ischemia of the hand are discussed in the following subsections, while Box 60.1 offers a historical review.

Open Arterial Trauma

Arterial trauma is reasonably common in the upper extremity and can be due to laceration or closed injury, as noted earlier. Reviews have noted that the majority of these injuries are open (i.e., in the 79% range) and that most result from lacerations. The options for management differ somewhat and are discussed here. Open arterial trauma generally requires exploration because there is a wound that needs to be managed, and likewise, injuries to other structures almost always will require repair.

In general, preoperative workup of patients with an open vascular injury is limited to physical examination because a high index of suspicion should be present based on the history and location of the injury. Arterial studies are generally not indicated in open injuries with the exception of gunshot wounds with an otherwise normal examination of motor and sensory systems. It should be noted, however, that clinical studies have demonstrated that up to 50% of vessels with a proximal injury will have a palpable pulse at the wrist. If the limb is well perfused, delay in management of the injury (i.e., beyond 6 hours) if the bleeding is controlled and the patient is hemodynamically stable has not been shown to be detrimental. It also has been shown in the military’s experience during recent conflicts that temporary arterial shunting is a valuable adjunct in the management of arterial injuries. In such patients, shunts were left in as long as 11 hours and in some cases until definitive repair could be performed. The results between patients who had immediate vascular repair and those shunted showed no significant differences in outcomes.

At the time of exploration, the wound will need to be extended in order to allow exploration and repair of the injured structures ( Fig. 60.6 ). If the hand is well perfused, a decision needs to be made as to whether repair of the injured vessel is important to the circulation in the hand. The brachial artery can suffer injury from fractures about the elbow, particularly in children with closed supracondylar humeral fractures. ^, Such injuries can lead to significant ischemia of forearm muscles and the hand. Studies have demonstrated that single-vessel (i.e., radial or ulnar artery) injuries in the forearm lead to little long-term sequelae even if the injured vessel is simply ligated.

The flow in the remaining vessel has been shown to increase with injury or ligation of the other, and patency rates of repaired single vessels have been shown to be surprisingly low (i.e., in the 50% range), even with proper technique. Arterial injuries combined with median nerve injuries have been shown to lead to increased long-term problems, probably more related to nerve injury than arterial injury. In younger patients and in those with possible vascular compromise from other factors, repair of the radial or ulnar arteries in the forearm almost certainly should be undertaken.