13 - Peripheral Vascular Diseases

13.1About peripheral vascular diseases

Overview

The term peripheral vascular diseases (PVDs) refers to circulatory disorders involving any of the blood vessels outside the heart, e.g. arteries, veins and lymphatics of the peripheral vasculature.  The four subcategories of PVDs that have the greatest relevance for driving are:

  • peripheral arterial disease
  • aneurysms
  • dissections, and
  • deep vein thrombosis.

Peripheral arterial disease

Peripheral arterial disease (PAD) is characterized by partial or complete failure of the arterial system to deliver oxygenated blood to peripheral tissue.  Atherosclerosis is the primary underlying cause of PAD.  Other causes include thrombembolic, inflammatory or aneurismal disease.  Although PAD can affect both upper and lower extremities, lower extremity involvement is more common.  A large majority (70% to 80%) of individuals with PAD are asymptomatic.  For those individuals who are symptomatic, symptoms can progress from intermittent claudication (pain while walking) to rest/nocturnal pain, to necrosis/gangrene.  Only 1% to 2%, however, progress to limb amputation within 5 years of the original diagnosis.

Aneurysms

An aneurysm is defined as a localized abnormal dilation of an artery by 50% above the normal size. Although an aneurysm can form on any blood vessel, abdominal aortic aneurysms (AAA) are most common, with 90% occurring below the renal arteries.

Others include those occurring in the thoracic aorta (ascending 5%; aortic arch 5%; descending 13%), those in the combined thoracic and abdominal aorta (14%) and iliac aneurysms (isolated 1%; combined abdominal and iliac 13%).

Aortic dissection

Aortic dissection is a different disease to aortic aneurysm.  Most dissections are in apparently normal aortas, are sudden and often present with collapse.  Apart from some congenital conditions which predispose to dissections, e.g. Marfan’s, there is no way to predict an aortic dissection.

Deep vein thrombosis

Deep vein thrombosis (DVT) occurs when a thrombus (blood clot) forms within a deep vein, most commonly in the calf. Three main factors (known as Virchow's triad) can contribute to deep vein thrombosis: injury to the vein's lining, an increased tendency for blood to clot, and slowing of blood flow.

13.2Prevalence

Peripheral arterial disease

Estimates of the prevalence of PAD depend on populations studied and study methodology.  The general prevalence rate is reported to be 10%.   However, because most individuals remain asymptomatic, the true overall prevalence rate is likely to be considerably higher.  The prevalence of PAD increases with age and with prolonged exposure to smoking, hypertension and diabetes.

Recent studies indicate that PAD affects approximately 20% of adults 55 years of age and older and an estimated 27 million persons in North America and Europe.  Intermittent claudication is the most common symptom associated with PAD.  The prevalence of intermittent claudication increases dramatically with age. The incidence in the general population is less than 1% of those under the age of 55, and increases to 5% for those 55 to 74 years of age.  At younger ages, the prevalence rate is almost twice as high for males as for females but, at the older ages, the difference between males and females is reduced. Risk factors for lower extremity PAD are:

  • age less than 50 years, with diabetes and one other atherosclerosis risk factor (smoking, dyslipidemia, hypertension or hyperhomocysteinemia)
  • age 50 to 69 years and history of smoking or diabetes
  • age 70 years and older
  • leg symptoms with exertion (suggestive of claudication) or ischemic rest pain
  • abnormal lower extremity pulse examination, and
  • known atherosclerotic coronary, carotid or renal artery disease.

Abdominal aortic aneurysms

Based on results from a population-based study completed in 2001, the prevalence of abdominal aortic aneurysms is approximately 9% for males and 2.2% for females.

Prevalence increases with age and is higher in close family relatives of those affected. Prevalence also is higher in individuals with cardiovascular risk factors such as cigarette smoking, hypertension and hypercholesterolemia.

Deep vein thrombosis

The prevalence of DVT is estimated to be < 0.005% in individuals less than 15 years of age, and increases to approximately 0.5% for individuals 80 years of age and older.

Approximately one-third of patients with symptomatic DVT will develop a pulmonary

embolism, which is the obstruction of the pulmonary artery, or a branch of it leading to the lungs, by a blood clot.

13.3Peripheral vascular diseases and adverse driving outcomes

There are no studies that consider a relationship between peripheral vascular diseases and risk of crash.

13.4Effect on functional ability to drive

Condition Type of driving impairment and assessment approach Primary functional ability affected Assessment tools

Peripheral arterial disease – severe claudication

Persistent impairment: Functional assessment

Sensorimotor

Motor

Medical assessments Functional assessment
Abdominal aortic aneurysm Episodic impairment: Medical assessment – likelihood of impairment All – sudden incapacitation Medical assessments
Aortic dissection Episodic impairment: Medical assessment – likelihood of impairment All – sudden incapacitation Medical assessments
DVT - may result in pulmonary embolism Episodic impairment: Medical assessment – likelihood of impairment All – sudden incapacitation Medical assessments

Peripheral arterial disease

For drivers with peripheral arterial disease, the chronic outcomes of the disease will rarely affect driving ability. The symptoms of lower extremity PAD such as coldness or numbness in the foot or toes and, in the later stages, pain while the extremity is at rest, may affect the sensory and motor functions required for driving.

In general, the degree of impact will be determined by disease severity.  For example, drivers who are asymptomatic or have mild to moderate claudication are unlikely to have symptoms that would affect driving.  Drivers whose disease has progressed to the severe claudication stage or higher may have functional impairment sufficient to interfere with the lower extremity demands of operating a motor vehicle (e.g. awareness of foot placement, pedal pressure, motor strength, etc.).

Abdominal aortic aneurysm and aortic dissection

For drivers with an abdominal aortic aneurysm, acute complications may affect driving ability.  The primary concern with an abdominal aortic aneurysm is the risk of rupture. The majority of aneurysms are asymptomatic and research suggests that there are few or no symptoms prior to rupture.  There is limited data on the immediate functional outcomes of rupture (e.g. loss of consciousness).  In the absence of firm data, it is assumed that most drivers experiencing a rupture lose consciousness almost immediately. As with AAA, the primary concern for a driver with an aortic dissection is the risk of rupture.

Size and rate of expansion of abdominal aortic aneurysms and aortic dissections are determined by sequential CT or Ultrasound imaging. Only the anterior-posterior or transverse diameter is predictive of rupture; the length of the aneurysm has no relation to rupture.

Deep vein thrombosis

For drivers with deep vein thrombosis (DVT), acute complications may affect driving ability.  The primary concern with DVT is the risk of sudden incapacitation due to a pulmonary embolism.

13.5Compensation

Drivers are not able to compensate for the effects of an AAA, aortic dissection or DVT.

Drivers with an amputation resulting from PAD may be able to compensate for functional impairment through strategies and/or vehicle modifications.  For example:

  • for loss of limb, a driver may compensate through the use of a prosthetic device when driving
  • drivers with PAD may be able to compensate for a functional impairment by driving a vehicle that has been modified to address their impairment. Compensatory vehicle modifications can include modifications to driving controls (e.g. hand controlled throttle and brake).

An occupational therapist, driver rehabilitation specialist, driver examiner or other medical professional may recommend specific compensatory vehicle modifications based on an individual functional assessment.

13.6Guidelines for assessment

13.6.1 Peripheral arterial disease

If a driver has lost a limb due to peripheral arterial disease, also see standard 11.6.1.

National Standard

All drivers eligible for a licence if

  • the peripheral arterial disease is successfully treated
BC Guidelines
  • If further information on an individual’s medical condition is required, RoadSafetyBC may request
    • a Driver’s Medical Examination Report, or
    • additional information from the treating physician
  • If the treating physician indicates that the individual has severe claudication, or foot and leg symptoms that may impair their functional ability to drive, RoadSafetyBC may request an ICBC road test
  • If an ICBC driver examiner recommends further assessment, RoadSafetyBC may request
  • additional information regarding the individual’s medical condition, and/or an assessment from an occupational therapist or driver rehabilitation  specialist
Conditions for maintaining licence No conditions are required
Reassessment
  • For non-commercial drivers, RoadSafetyBC will re-assess every 5 years if successfully treated or mild claudication.  RoadSafetyBC may re-assess more frequently, upon the recommendation of the treating physician, if moderate or severe claudication
  • For commercial drivers, routine commercial re-assessment applies, unless more frequent re-assessment is recommended by the treating physician
Information from health care providers
  • Opinion of treating physician on whether there is severe claudication or foot and leg symptoms that may impair functional ability to drive
  • Where required, the results of a functional assessment
  • Opinion of the treating physician regarding whether the driver has insight into the impact their medical condition may have on driving
  • Whether the driver is compliant with their current treatment regime
Rationale Where peripheral arterial disease results in a functional impairment, the impact of the impairment on driving should be determined by an individual functional assessment.

13.6.2 Abdominal aortic aneurysm or medically treated aortic dissection – Non- commercial drivers

National Standard

Non-commercial drivers eligible for a licence if

  • the aneurysm or dissection is not at the stage of imminent rupture as determined by size, location or recent change, and
  • for men, the diameter of the aneurysm or dissection is < 6.5 cm and the conditions for maintaining a licence are met, or
  • for women, the diameter of the aneurysm or dissection is < 6 cm and the conditions for maintaining a licence are met
BC Guidelines

If further information is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or
  • additional information from the treating physician, such as a report from within the past year indicating the diameter of the aneurysm or dissection
Conditions for maintaining licence No conditions are required
Reassessment If the diameter of the aneurysm or dissection is over 5 cm, RoadSafetyBC will re-assess annually. If the diameter is between 4 and 5 cm, RoadSafetyBC will re-assess every two years. If the diameter is under 4 cm, RoadSafetyBC will re-assess every 5 years, unless routine age-related re- assessment applies
Information from health care providers
  • Size of aneurysm or dissection in greatest diameter
  • Whether condition is regularly reviewed
Rationale
  • The primary concern with AAA and aortic dissection is the risk of rupture.  The risk of rupture increases with the size of the aneurysm. The size threshold for non-commercial drivers has been set at just over the point at which surgery to repair the aneurysm or dissection is generally considered advisable given the risk of rupture
  • Aneurysms less than 5 cm in diameter have an annual incidence of rupture of 4.1%, which increases to 6.6% in aneurysms between 5 and 5.7 cm.  Aneurysms larger than 7 cm in diameter have 19 percent per year incidence of rupture.  This means that most patients (75%) with this size of aneurysm will have a rupture within 5 years

13.6.3 Abdominal aortic aneurysm or medically treated aortic dissection – Commercial drivers

National Standard

Commercial drivers eligible for a licence if

  • the aneurysm or dissection is not at the stage of imminent rupture as determined by size, location or recent change, and
  • for men, the diameter of the aneurysm or dissection is < 6 cm and the conditions for maintaining a licence are met, or
  • for women, the diameter of the aneurysm or dissection is < 5.5 cm, and the conditions for maintaining a licence are met
BC Guidelines

If further information is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or
  • additional information from the treating physician, such as a report from within the past year indicating the diameter of the aneurysm or dissection
Conditions for maintaining licence No conditions are required
Reassessment
  • If the diameter of the aneurysm or dissection is over 4 cm, RoadSafetyBC will re-assess annually.
  • If the diameter is between 3 and 4 cm, RoadSafetyBC will re-assess every two years
  • If the diameter is under 3 cm, RoadSafetyBC will re-assess every 3 years
Information from health care providers
  • Size of aneurysm or dissection  in greatest diameter
  • Whether condition is regularly reviewed
Rationale
  • The primary concern with AAA and aortic dissection is the risk of rupture.  The risk of rupture increases with the size of the aneurysm. The size threshold for commercial drivers has been set at the point at which surgery to repair the aneurysm or dissection is generally considered advisable given the risk of rupture.  This threshold is lower than the threshold for non-commercial drivers to reflect the additional risk presented by the increased driving exposure for commercial drivers
  • Aneurysms less than 5 cm in diameter have an annual incidence of rupture of 4.1%, which increases to 6.6% in aneurysms between 5 and 5.7 cm. Aneurysms larger than 7 cm in diameter have 19 percent per year incidence of rupture.  This means that most patients (75%) with this size of aneurysm will have a rupture within 5 years

13.6.4 Surgically repaired abdominal aortic aneurysm or surgically treated aortic dissection

National Standard

All drivers eligible for a licence if

  • the abdominal aortic aneurysm has been surgically repaired, or the aortic dissection has been surgically treated, and
  • the treating physician supports a return to driving
BC Guidelines

If further information is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or
  • additional information from the treating physician

 If any complications from the surgery are indicated, RoadSafetyBC may request a report from the vascular surgeon supporting return to driving

Conditions for maintaining licence None
Reassessment RoadSafetyBC will not re-assess, other than routine commercial or age-related re-assessment
Information from health care providers

Opinion of the treating physician whether the surgery was successful in repairing the aneurysm or treating the dissection

Rationale
  • The primary concern with AAA and aortic dissection is the risk of rupture.  Successful surgery to repair an aneurysm or dissection will significantly reduce the risk of rupture
  • Surgical repair is considered where an aneurysm is greater than 5.5 cm.  A recent study suggests that women’s aneurysms rupture at smaller sizes, leading to the conclusion that the 5.5 cm threshold for surgical repair is likely too large for women and 5 cm has been suggested as the appropriate level

13.6.5 Deep vein thrombosis

National Standard

 All drivers eligible for a licence if

  • treated with an anticoagulant, and
  • treating physician states that the treatment is effective
BC Guidelines RoadSafetyBC will not generally request further information
Conditions for maintaining licence None
Reassessment RoadSafetyBC will not re-assess, other than routine commercial or age-related re-assessment
Information from health care providers
  • Whether the driver is being treated with an anticoagulant
  • Treating physician’s opinion that the DVT has been successfully treated
  • Whether the driver has insight into the impact their medical condition may have on driving
  • Whether the driver is compliant with their current treatment regime
Rationale The primary concern with DVT is the risk of sudden incapacitation due to a pulmonary embolism