Vascular Conditions

Michael Alexander McClinton

Vascular ‘conditions’ generally fall into two categories: Vascular mass or ischemia. An estimated 10% of the U.S. population has some form of ischemia. This may be a chronic non-limb-threatening annoyance or may jeopardize digit or limb survival. The vascular workup determines whether immediate treatment is indicated or whether the patient may, with a few lifestyle modifications, live with the condition. A vascular mass should be suspected any time that a tumor overlies the course of an artery, or there are embolic symptoms at the distal arterial tree, especially if this is unilateral. This chapter will review the anatomy, physiology, and medical evaluation of vascular lesions, followed by the individual conditions.

I. Definitions

Functions of vascular system
- Delivers oxygen and nutrition to cells
- Core temperature maintenance
- Removes waste products of metabolism
Vascular incompetence—Koman: Inadequate arterial inflow due to structural damage to arteries, or inappropriate vascular control from nerve or hormonal abnormality
Critical vascular event versus noncritical vascular event—Koman
- Critical: Tissue death and necrosis without intervention
- Noncritical: Collateral circulation maintains tissue viability

II. Anatomy

Macroarterial upper extremity vascular system (see Ch 21, Section 1.)
- Begins at the heart and great vessels
- Brachial artery branches just distal to the antecubital fossa
- From that point on there are redundant vascular channels
  - Forearm: Radial, ulnar, and interosseous arteries
  - Wrist/hand: Superficial, deep palmar, and dorsal arterial arches
  - Digits: Radial, ulnar digital arteries, and digital arches
- Superficial palmar arterial arch is complete in 80% of hands, that is, either radial or ulnar artery can supply all digits. The deep palmar arterial arch is complete in 97% of hands.
Microarterial system
- Peripheral vascular system vessels are less than 100 µm in diameter or circumference?
  - Smooth muscle in arterial wall is sensitive to circulating chemicals and local sympathetic nerves.
  - Blood flows between arteries and veins either through nutritional capillary beds or through parallel thermoregulatory AV shunts.
- Only 10% of arterial flow is needed for skin viability; 90% is for temperature regulation.
- If blood flow is inadequate to the nutritional capillary beds, tissue ulceration, ischemia, and necrosis may occur.

III. Blood Flow Physiology

Larger vessels follow laws of fluid dynamics: diameter, pressure, and resistance
Critical arterial stenosis: Blood flow decreases minimally with reduction in arterial diameter until a critical point, about 50%.
Vascular wall control: Central nervous system and local vascular control act through nerve innervation or circulating vasoactive chemicals including vasoconstrictors, vasodilators, and thrombolytic or thrombogenic substances.
Compensatory mechanisms to combat ischemia following stenosis: Arterial dilatation, collateral vessel formation, and lowered arterial resistance secondary to vasodilators released from the vessel endothelium.

IV. Evaluation

Office evaluation
- Medical history
  - Usual complaints: Vascular mass or ischemic symptoms
  - Acute or chronic trauma including repetitive hand injury or vibration exposure
  - Systemic illnesses: Hematologic, metabolic (diabetes), connective tissue, and atherosclerosis
  - Medication/drug exposure especially vasoactive drugs
  - Tobacco products
- Physical examination
  - Inspection of upper limb skin and fingernails for rash, ulcerations, splinter hemorrhages, scars, narrowing of the nails (sclerodactyly), clubbing, and hair pattern
  - Hand color: Pale, redness, and cyanosis
  - Temperature differences between upper limbs or between individual digits
  - Masses with overlying audible bruit or palpable thrill
  - Arterial pulses at elbow and wrist
- Allen test: Compress both arteries at the wrist, patient closes and then opens fist, sequentially release one then the other artery. Look for time and completeness of blood return to the digits. Longer than 6 seconds indicates narrowing or occlusion of a wrist artery.
- Doppler examination: Ultrasonic flowmeter measures blood flow by detecting the changing frequency of reflected sound waves from moving red blood cells. The output data from the Doppler are converted to audible sound waves. Listen to wrist and palmar arch arterial sounds, then digit sounds. Occlude sequentially radial and ulnar arteries while listening to digital sounds to augment findings from the Allen test.
- Digital Allen test: Doppler distal pulp of a finger while occluding first the radial and then the ulnar digital artery. Test determines if a digital artery is occluded.
- Additional tests
  - Echocardiogram to look for surface abnormalities in the heart that could be the source of emboli to the upper limb (valvular vegetation, atrial myxoma, atrial thrombus, septal defect)
  - Blood studies primarily aimed at detecting clotting disorders and vasculitis
Noninvasive vascular testing
- Greatly extends the clinician’s office evaluation
  - 97% agreement between noninvasive testing and findings from arteriography and surgery
  - Identifies location of vascular pathology
  - Determines the severity of vascular compromise
  - Allows repeated follow-up of nonsurgical and surgical therapy
- Segmental arterial pressure measurements
  - Single most valuable laboratory tool
  - Doppler unit and an occlusive pressure calibrated cuffs allow the measurement of systolic blood pressure at any level along the extremity and between extremities
  - Greater than 15 mm Hg difference between different extremities or different levels on the same extremity is usually significant
  - Mean arterial pressure less than 70 mm Hg denotes ischemia
- Digital/brachial index (DBI) standardizes the different digit arterial measurements by dividing them by the higher of the two brachial arterial pressures. This measurement allows standardized testing and reporting between different persons. Normal DBI—1.0; ischemic DBI—<0.7
- Pulse volume recording (PVR, plethysmography)
  - Volume changes in the digits correlate with arterial inflow and egress, which is converted to an analog signal.
  - Characteristic pulse volume tracings for normal, stenotic, and occluded vessels
  - Cold stress testing applied to the hands; then measuring PVR identifies patients with vasospastic disease.
- Color duplex imaging
  - Color-coded combination of Doppler signal and pulse-echo that gives an actual image as well as flow information.
  - Compared to arteriogram, this technique is noninvasive, cost efficient, repeatable, and portable; the images are less distinct
  - Indicated for evaluation of masses to determine whether they are vascular, for example, wrist volar ganglion versus radial artery aneurysm
  - Can also be used to study vascular perfusion in ulnar artery thrombosis, acute arterial trauma, and postoperative arterial repair problem
- Skin surface temperature: Digital skin temperature measurements correlate with total blood flow below 30° C
Radiologic evaluation
- Magnetic resonance imaging (MRI)
  - Noninvasive, low risk of vascular spasm
  - Nonionizing radiation, or iodinated contrast reactions
  - Useful for evaluating congenital and acquired masses
- Magnetic resonance arteriography (MRA)
  - Blood flow highlighted to show vessels
  - Difficult in small, stenotic, or occluded vessels
  - Gadolinium-enhanced test improves visualization of vascular structures
- Contrast arteriography
  - Gold standard for vascular evaluation
  - Best anatomic and structural arterial detail
  - Risks with this technique preclude its use as a screening tool for extremity ischemia
  - Generally, catheter is inserted into the femoral artery and passed through the aorta to the great vessels and extremity arteries
  - Have radiologist use intravascular vasodilators
  - Communication with the radiologist performing the procedure is critical to obtain specific and accurate information
  - Begin at the great arch and proximal vessels to rule out vascular thoracic outlet syndrome
  - Complications: Injection injury to the catheterized artery; catheterinduced vasospasm; emboli dislodged; vasospasm distorted picture of the distal arterial tree; intervention is possible with thrombolytics through the catheter

V. Congenital Vascular Disorders

Definition: Confusing terminology, because “hemangioma” is often used to refer to any vascular growth in a child. The important point is to distinguish between a hemangioma (an involuting tumor) and venous malformation (a noninvoluting tumor).