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The ischemic hand


Synopsis

  • ■

    Upper extremity ischemia is caused by many etiologies and may be classified into acute and chronic cases.

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    A precise understanding of arterial anatomy is pertinent to preoperative diagnosis, patient selection, and operative procedure.

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    A history of cold intolerance, Raynaud’s phenomenon and frequency of ischemic pain is important. Color changes, ulcerations, and infections are evaluated.

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    Noninvasive vascular examination includes measurement of fingertip temperatures, Doppler ultrasound, segmental arterial pressures, and capillaroscopy.

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    Even though arteriography is invasive, it is the most valuable investigation detecting arterial abnormalities of the hand – obstruction, stenosis, ectasia, coiling, aneurysm, and velocity of flow.

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    Various pharmacologic agents can be used to counteract the sympathetic effect on the muscular layers of the arterial wall in a conservative medical approach.

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    Surgical intervention consists of interrupting the sympathetic innerva­tion of the arterial wall, physical dilatation of the stenotic lumen, and microsurgical reconstruction of the occluded artery.

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Introduction

Hand ischemia occurs when the vascular system is no longer able to transport blood efficiently because of trauma, constriction, obstruction, or vasospasm. It is the critical vascular event that results in eventual tissue necrosis and even amputation without proper management. Compared with the lower extremity, the symptomatology and presentation are varied in the upper limb, and it is frequently underdiagnosed. Upper extremity ischemia is caused by many etiologies and may be classified into acute and chronic cases ( Box 28.1 ). Any microvascular injury that diminishes the vascular flow induces the acute ischemic conditions of the hand. Systemic, congenital, and genetic problems also cause chronic ischemic conditions. Raynaud’s phenomenon is a well-known vasospastic condition that affects 3–5% of the general population. Primary Raynaud’s phenomenon occurs in the absence of any underlying condition, whereas secondary Raynaud’s phenomenon is associated with other vasospastic conditions.

Box 28.1
Etiology of acute and chronic ischemia of the hand

  • A.Acute Ischemia

    • Trauma

    • Direct arterial injury

    • Shoulder dislocation

    • Supracondylar fracture of the humerus

    • Posterior dislocation of the elbow

    • Frostbite

    • Irradiation

    • Arterial emboli

    • Atrial fibrillation

    • Myocardial infarction

    • Poststenotic dilatation of subclavian artery

  • Iatrogenic injury

    • Cannulation injury; brachial artery, radial artery

    • Intra-arterial drug injection injury

    • Hemodialysis access; shunts and fistulas

  • Septicemia

  • B. Chronic Ischemia

    • Connective tissue disorders

    • Scleroderma

    • Systemic lupus erythematous

    • Dermatomyositis

    • Sjögren syndrome

    • Undifferentiated connective tissue disease

    • Mixed connective tissue disease

    • Overlap syndrome

    • Granulomatosis with polyangiitis (Wegener’s)

  • Arterial thrombosis; occupational related

    • Hypothenar hammer syndrome

    • Vibration-related white finger syndrome

  • Aneurysm

  • Vascular disease

    • Buerger’s disease

    • Atherosclerosis: proximal (more common) or distal

    • Renal vascular disease

    • Cervical rib compression

  • Hematologic and oncologic disorder

    • Polycythemia

    • Leukemia

    • Myeloma

    • Cryoglobulinemia

  • Endocrinologic disorder

    • Hypothyroidism or hyperthyroidism

    • Autoimmune thyroiditis

  • Toxin- or drug-related disorder

Jones categorized hand ischemia into subgroups of acute and chronic disease. There are multiple causes of upper extremity ischemia, but a classification system based on the underlying pathophysiologic mechanism responsible for producing the ischemia would seem to be most appropriate as a rationale for suitable treatment. He described five main pathophysiological mechanisms of hand ischemia: emboli, thrombosis, occlusive disease, vasospasm, and low flow states.

Regardless of its causes, ischemia of the hand is manifested by color and temperature changes, pale fingers, cold intolerance, numbness, digital ulcerations, and gangrenous changes. Despite appropriate treatments, such as smoking cessation, cold avoidance, biofeedback techniques, and pharmacological therapy, ischemia commonly progresses to the eventual consequence of amputation. This chapter provides an insight to accurate diagnosis and appropriate treatment to avoid devastating tissue losses.

Raynaud’s phenomenon

Raynaud’s phenomenon of the hand is a clinical diagnosis, describing a temporary ischemic condition of the hand caused by vasospasm in the digital arteries. It is typically triggered by cold exposure, psychologic stress, and other sympathomimetic drives. Raynaud’s phenomenon in patients with upper extremity ischemia is common and classically consists of an orderly progression of three phasic color changes (white, blue, and then red) and symptoms in the affected hand secondary to vasospasm. Pallor is followed by a cyanotic appearance, and culminates with reactive hyperemia and burning pain or dysesthesias. This classic pattern occurs in about two-thirds of affected patients. Using an expert committee for a Delphi exercise, international consensus criteria for the diagnosis of Raynaud’s phenomenon were established in 2013. A three-step approach for the diagnosis of Raynaud’s phenomenon and five additional criteria for the diagnosis of primary Raynaud’s phenomenon were developed ( Boxes 28.2 & 28.3 ).

Box 28.2
Three-step diagnosis for Raynaud’s phenomenon
From Maverakis E, Patel F, Kronenberg DG, et al. International consensus criteria for the diagnosis of Raynaud's phenomenon. J Autoimmun . 2014;48:60–65.

Step 1: Ask screening question

  • Are your fingers usually sensitive to cold?

  • If yes, proceed to step 2

Step 2: Assess color changes

  • Occurrence of biphasic color changes during the vasospastic episodes (white and blue)

  • If yes, proceed to step 3

Step 3: Calculate disease score

  • a.

    Episodes are triggered by things other than cold (i.e. emotional stressors)

  • b.

    Episodes involve both hands, even if the involvement is asynchronous and/or asymmetric

  • c.

    Episodes are accompanied by numbness and/or paresthesias

  • d.

    Observed color changes are often characterized by a well-demarcated border between affected and unaffected skin

  • e.

    Patient provided photograph(s) strongly support a diagnosis of RP

  • f.

    Episodes sometimes occur at other body sites (e.g. nose, ears, feet and areolas)

  • g.

    Occurrence of triphasic color changes during the vasospastic episodes (white, blue, red)

If 3 or more criteria met from step 3 (a–g), then the patient has Raynaud’s phenomenon

Box 28.3
Diagnostic criteria for primary Raynaud’s phenomenon
From Maverakis E, Patel F, Kronenberg DG, et al. International consensus criteria for the diagnosis of Raynaud's phenomenon. J Autoimmun . 2014;48:60–65.

  • Meets 3-step criteria for diagnosis of Raynaud’s phenomenon

  • a.

    Normal capillaroscopy

  • b.

    Physical examination is negative for findings suggestive of secondary causes, (e.g. ulcerations, tissue necrosis or gangrene, sclerodactyly, calcinosis, or skin fibrosis)

  • c.

    No history of existing connective tissue disease

  • d.

    Negative or low titer ANA (e.g. 1:40 by indirect immunofluorescence)

Raynaud’s phenomenon is currently classified into primary Raynaud’s phenomenon and secondary Raynaud’s phenomenon according to the presence of an underlying disease. Primary Raynaud’s phenomenon is diagnosed when no underlying condition is found, whereas secondary Raynaud’s phenomenon is associated with other vasospastic or occlusive conditions ( Table 28.1 ). Secondary Raynaud’s phenomenon is commonly caused by autoimmune disorders including systemic sclerosis, systemic lupus erythematosus, and other connective tissue disorders. One study showed that 37.2% of 3029 persons who were diagnosed with primary Raynaud’s phenomenon subsequently developed a connective tissue disease, commonly systemic sclerosis. Additionally, there are several other non-autoimmune causes of secondary Raynaud’s phenomenon, such as hematologic, endocrine, vascular, neurologic, environmental and drug or toxin-related disorders.

Table 28.1
Primary Raynaud phenomenon vs. secondary Raynaud phenomenon
Characteristics Primary Raynaud phenomenon Secondary Raynaud phenomenon
History
At least biphasic color change Yes Yes
Age Younger (usually between 15 and 30 years) Older
Progression rapid No Yes
Secondary causes No Yes
Female predominance Frequent Occasional
Physical examination
Trophic findings (ulcer, gangrene) No Frequent
Thumb sparing Generally spared Possibly involved
Abnormal Allen test No Common
Asymmetric findings Infrequent Frequent
Laboratory testing
Blood chemistry Normal Frequently abnormal
Antinuclear antibody Negative or low-titer (≤1:40 by indirect immunofluorescence) Frequently abnormal
Endothelial dysfunction No Probably present
Imaging findings
Capillaroscopy (nail fold capillary) Normal Frequently abnormal
Angiography Normal Frequently abnormal

Raynaud’s phenomenon involves specific skin regions, which have a high density of arteriovenous anastomoses, providing direct connections between arterioles and venules for thermoregulation. In patients with Raynaud’s phenom­enon, cold-induced sympathetic vasoconstriction amplifies the already-heightened sympathetic vasoconstriction throughout the vascular network, including arteries, arteriovenous anastomoses, and arterioles. Although nutritional flow is normally not affected by cold-induced sympathetic vasoconstriction, endothelial dysfunction in secondary Raynaud’s phenomenon with scleroderma destroys this protective mechanism, resulting in tissue injury and ulcerations. Local cooling induces sympathetic vasoconstriction by releasing norepinephrine in the sympathetic nerve and stimulating α 2 -adrenergic receptors located on smooth-muscle cells. Endothelial cells increase nitric oxide (NO) and prostacyclin as mediators of vasodilatation. NO also reduces the release of endothelial storage granules, which store von Willebrand factor (VW) and endothelin-1 (ET-1) peptides. Endothelial dysfunction in secondary Raynaud’s phenomenon impairs this protective vasodilatation with diminished activity of NO and increased expression and release of ET-1.

Historical perspective

Maurice Raynaud described Raynaud’s phenomenon in 1862 and attributed the condition that bears his name to overactivity of the sympathetic nervous system, but a review of his cases reveals that most of his patients probably had small-vessel occlusive disease. He hypothesized that “local asphyxia of the extremities” was a result of “increased irritability of the central parts of cord presiding over vascular innervations”.

Lewis first postulated a peripheral rather than central mechanism for Raynaud’s disease caused by a “spasm of digital arteries”. He stated that “the abnormal element in the reaction to cold is a direct reaction and due to a peculiar condition of the vessel wall locally: it is not the result of a reflex through the vasomotor nerves”. However, the pathophysiology remained poorly understood.

Basic science

Anatomy

Embryology

The limb buds appear at 4 weeks of embryonic life as lateral swellings and the forearm vasculature evolves through several stages between 4 and 8 weeks. A median artery, ulnar artery, and radial artery arise in order from the brachial artery at the elbow, but the median artery involutes as the radial and ulnar arteries provide the majority of blood flow to the hand.

Arterial system in the forearm, hand, and digits

Variations in the vascular pattern of the deep and superficial palmar arches and the common digital arteries are frequent. Therefore, a precise understanding of arterial anatomy is pertinent to preoperative diagnosis, patient selection, and operative procedure.

Superficial palmar arch

The superficial palmar arch may be classified as either “complete” or “incomplete”. This classification provides the simplest understanding of the anatomy of the arches. An arch is considered to be complete if an anastomosis is found between the vessels constituting it. An incomplete superficial arch is defined as one in which the contributing arteries do not anastomose, or when the ulnar artery fails to reach the thumb and index finger. In a recent meta-analysis study, the superficial palmar arch was usually complete (81.3%), with the radio-ulnar anastomosis being the most common variant (72.0%).

Multiple variations of the superficial palmar arch have been classified into subgroups. According to Gellman’s study, complete arches have been divided into five subgroups.

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    Type A: The radioulnar arch is formed by anastomosis between the superficial volar branch of the radial artery and the continuation of the ulnar artery.

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    Type B: The superficial arch is formed by a continuation of the ulnar artery and even provides common digital vessels to the thumb and index web space.

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    Type C: The median and ulnar arteries combine to form the superficial arch without a contribution from the radial artery.

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    Type D: This is characterized by all three vessels (radial, median, ulnar) contributing to the arches.

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    Type E: A branch from the deep palmar arch communicates with an ulnar artery-initiated superficial arch.

The main branches from the superficial palmar arch are the three common digital arteries to the index–middle, middle–ring, and ring–small finger web spaces and the proper digital artery to the ulnar border of the small finger. When the princeps pollicis artery and a vessel to the radial side of the index finger (index radial digital artery) originates from the superficial palmar arch, this should be named as the first common digital artery.

Deep palmar arch

The deep palmar arch is less variable than the superficial arch. The radial artery forms the deep arch when it passes from dorsal to palmar by piercing the two heads of the first dorsal interosseous muscle. The arch then curves along the bases of the metacarpal bones. The deep arch may anastomose with one or both volar branches of the ulnar artery. At least one of the deep volar branches was present in all individuals in a recent study. The deep palmar arterial arch travels across the palm, deep to the flexor tendons, at the level of the carpometacarpal joints to connect with a deep arterial branch from the ulnar artery. The deep palmar arch gives rise to as many as five palmar metacarpal arteries that pass distally to the level of the metacarpal heads, where they branch dorsally to join the dorsal metacarpal arteries and also connect to the common digital artery through a small palmar arterial branch. Nystrom et al . described three palmar and three dorsal arches which connect the four forearm arteries (ulnar, median, radial, and interosseous arteries). Dorsal metacarpal arteries which originate from the dorsal carpal arches pass to their respective web spaces distally, where they join perforating vessels from the palmar circulation.

The most consistent of the dorsal vessels supplying the dorsal carpal rete, which consists of numerous small, thin vessels (0.3–0.5 mm), is the radial dorsal carpal branch. It branches off the radial artery 10–15 mm distal to the radial styloid.

When the superficial arch is well developed, the deep palmar arch is correspondingly less developed and vice versa. A reciprocal inverse relationship was also found between the common palmar digital arteries and the palmar metacarpal arteries.

Surgical landmarks of superficial and deep palmar arch

A study of 48 cadaveric hands suggested easily identifiable surface and bony landmarks of the superficial and deep palmar arches. The superficial palmar arch and deep palmar arch were found to be on average 15.3 ± 8.60 mm and 6.70 ± 4.82 mm distal to Kaplan’s cardinal line and on average 51.8 ± 7.56 mm and 40.1 ± 7.92 mm distal to the distal wrist crease, respectively. The average distances from the superficial palmar arch and deep palmar arch to the carpometacarpal joint of the ring finger were 32.2 ± 6.33 mm and 18.3 ± 4.64 mm, respectively.

Digital arteries

The ulnar digital arteries of the thumb and index finger are larger than the radial digital arteries. The radial digital artery is larger in the ring and small fingers. The difference between the radial and ulnar digital arteries is statistically significant only in the border digits. The anatomy of the thumb digital arteries is unique. The blood supply of the thumb comes mainly from the princeps pollicis artery, the terminal branch of the superficial palmar arch, and the first dorsal metacarpal artery. There are numerous sources of blood supply from the radial and ulnar arteries, including the palmar ulnar, palmar radial, dorsal ulnar, and dorsal radial arteries. The first palmar metacarpal artery is absent in about 2% of patients. This accounts for the tolerance of the thumb to ischemia due to numerous collateral blood vessels.

According to the Hagan–Poiseuille’s law, the blood viscosity, diameter, length, and the pressure gradient influence flow through the digital arteries, and larger digital arteries can carry more blood. Strauch and de Moura described the numerous interconnections between the digital arteries beyond the metacarpophalangeal joints. These connections play an important role in hand ischemia if segmental arterial obstruction develops.

Micro-arterial system

Microvascular vessels are defined as having a diameter of <100 µm. Their role is to deliver oxygen and nutrients at a cellular level. They consist of nutritional capillary and thermoregulatory vessels. In the digits, 80–90% of the total flow passes through thermoregulatory beds and 10–20% are involved in capillary nutrition. In pathologic states, cellular hypoperfusion leads to ischemic symptoms and imbalance in the distribution of thermoregulatory and nutritional flow resulting in cell death or damage.

Physiology of blood flow

Hemodynamics

Macrovascular structures are defined as vessels >100 µm. Their function is to deliver nutrients to the microvascular beds, provide adequate capacity for arteriovenous thermoregulatory flow and drain nutritional and thermoregulatory beds.

Cellular control mechanisms

Blood flow does not only follow principles of fluid dynamics. There is compensation between arterial dilatation, collateral vessels, and resistance in the peripheral circulation. In a normal extremity, blood flow in the hand depends on sympathetic tone, metabolic demands, environmental events, local factors, and circulating humoral mediators. Alpha-adrenergic control is the dominant control arm of vasoconstriction, however vasodilatation is initiated by endothelium-derived relaxing factor. Active vasoconstriction and vasodilatation may be initiated by a central control process mediated through peripheral neural structures or circulatory factors or by local autoregulation, which is metabolic or myogenic. Metabolic autoregulation occurs in response to local metabolic needs and is mediated by decreased oxygen and build-up of adenosine and potassium. Myogenic autoregulation is mediated via transmural pressure and stretch-operated calcium channels. The microcirculation is also affected by endothelial factors within blood vessels. The endothelium plays a major role in control of vasomotor tone and blood fluidity, lipid metabolism and finally angiogenesis. The endothelium has been recognized as an active tissue responsible for elaborating both vasodilatory and vasoconstrictor substances. Endothelial cells respond to differences in intravascular pressure due to variations in the size of the lumen by releasing endothelium-­derived relaxing factor. Endothelium-derived relaxing factor produces active vasodilatation, and endothelin is a potent vasoconstrictor. Both compounds are released from the endothelial cells to regulate vascular flow. Endothelial cells can also release thromboxane A2, prostacyclin, and the molecules of thrombomodulin and heparin sulfate.

Pathophysiology

As described previously, Fuchs classified arterial disease according to the three arterial layers: intima, media, and adventitia. Several pathologic processes (atherosclerosis, intimal hyperplasia) originate from this intimal layer. Endothelial disruption produces thrombotic occlusion and embolization. The media consists of smooth muscle cells, fibroblasts, and elastic tissue. Atherosclerosis leads to loss of tissue integrity, and the media becomes chronically dilated in a diffuse (ectasia) or localized (aneurysm) pattern. The adventitia is involved in diffuse pathologic conditions (arteritis, Buerger’s disease).

A classification system based on the underlying pathophysiological mechanism responsible for producing the ischemia would seem to be most appropriate as a rationale for determining treatment. The pathological processes that produce ischemia in any end organ (and the hand can be considered such an end organ) are emboli, “sludging” of blood in low flow states, thrombosis, external compression, intimal proliferation progressing to occlusion (arteriosclerosis), and vasospasm.

Emboli

Large emboli from the heart due to atrial fibrillation or myocardial infarction lodging at the bifurcation of the brachial artery are best managed by embolectomy by a vascular surgeon. However, smaller emboli or “micro-emboli” dislodged from an ulcerated atherosclerotic plaque in a large artery may lodge in the distal radial and ulnar arteries and digital arteries, and result in digital ulcerations or gangrene.

Trauma

Traumatic causes of ischemia can be occupational, iatrogenic, or secondary to an injury. Hypothenar hammer syndrome (HHS), first described by Van Rosen in 1934, is an uncommon cause of secondary Raynaud’s phenomenon, and occurs mainly in patients who use the hypothenar part of their hand as a hammer.

Because of its anatomic configuration within Guyon’s canal, the ulnar artery is particularly vulnerable to mechanical injury. The hook of the hamate bone presses against the superficial palmar branch of the ulnar artery in Guyon’s canal, leading to the development of progressive periadventitial scarring, damage to the media, disruption of the internal elastic lamina, intimal damage, and subintimal hematoma of the ulnar artery. These events are postulated to be the pathophysiological mechanism whereby repetitive trauma causes thrombosis in competitive athletes (volleyball, karate, handball, and baseball). A systematic review of HHS shows positive relationship between exposure of repetitive trauma and development of ulnar hammer syndrome, but there is lack of evidence regarding vibration exposure as a risk factor for ulnar hammer syndrome. A history of exposure to repetitive hand trauma and/or vibration, including factory workers, mechanics, metal workers, carpenters, masons, roofers, and woodmen, should be considered as a factor in the possible diagnosis of HHS.

“Vibration white finger” or vibration-induced Raynaud’s phenomenon is also related to repetitive trauma in workers who frequently use drills, jackhammers, and chain saws. High frequency vibration is assumed to affect the response of the sympathetic vasoconstrictor nerves and receptors, not only to mechanical- but also to thermal-induced pain.

Radial artery catheterization frequently results in radial artery thrombosis, although it is frequently asymptomatic because of communication between the radial and ulnar arterial systems. However, if the patient has an incomplete superficial palmar arch, distal ischemia may occur. Cardiac catheterization via the brachial artery may result in thrombosis and distal emboli, with an incidence of approximately 0.6%.

Arteriovenous shunt operations in renal failure patients may also result in hand ischemia. The arteriovenous shunt may redirect a critical volume of blood flow away from the hand, resulting in a “steal” phenomenon producing severe motor and sensory deficits.

Systemic disease

Systemic disease may produce distal hand ischemia and/or Raynaud’s symptoms, including connective tissue disease, vasculitis, malignancy, septicemia, arteriosclerosis, Buerger’s disease, polycythemia, cryoglobulinemia, and chemical toxicity.

Diagnosis/patient presentation

Evaluation

Evaluation of vascular competency should define the patient’s vascular anatomy and function under stressed and unstressed conditions. Therefore, a combination of studies is needed. Most importantly, a complete history and physical examination is essential in establishing a diagnosis. Investigations including noninvasive or invasive vascular studies may be required for exact evaluation of the patient’s status.

The patient’s symptoms, and studies such as Thermoscan, color Doppler and angiogram, are carefully reviewed to identify those patients who require surgical intervention.

History and physical examination

A history of cold intolerance, Raynaud’s phenomenon ( Fig. 28.1 ), and frequency of ischemic pain is important, as is smoking history; occupation involving repetitive injury or vibration trauma, and systemic disease including connective tissue disease, diabetes, cardiac disease, arrhythmias, drug use, blood dyscrasias, and peripheral neurological abnormalities. Unilateral Raynaud’s symptoms are especially suspicious and are usually indicative of occlusive disease on the affected side.

Figure 28.1, Triphasic color changes. (A) Fingers turn white. (B) Fingers turn purple.

A questionnaire was developed to assess the severity of cold sensitivity and quantify the magnitude, duration, and frequency of vasospastic symptoms and their effect on function.

A thorough examination of the upper extremity for previous trauma, old scars or operative incisions, skin color, temperature, presence of digital ulcers, and motor and sensory evaluation of the three peripheral nerves should be routine. Observation of blood flow in the fingernails may help to diagnose ischemia due to connective tissue disease.

Palpation may detect an abnormal mass or thrill. The brachial, radial, and ulnar arterial pulses are also palpated. The Allen test allows rapid evaluation of the patency of radial and ulnar arterial inflow into the hand. A digital Allen test can occasionally be performed either by forcing blood out of the finger or by sequential compression of the digital arteries.

Color changes, ulcerations, and infections are evaluated. Nonhealing ulcerations and/or impending gangrene associated with unilateral Raynaud’s symptoms are presumptive evidence of thrombosis or embolism.

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