1

Introduction

The development of fluoroscopically guided catheter-based interventions revolutionized the management of cardiovascular disease more than four decades ago. Since that time, innovations in devices and techniques have led to increasingly complex coronary interventions, new approaches to peripheral vascular and structural heart disease, catheter ablations, and numerous other procedures performed under fluoroscopy by interventional cardiologists, radiologists, and vascular surgeons. Despite remarkable advances in catheter-based technology, modern interventional procedures are performed in a manner remarkably similar to the techniques pioneered by Andreas Gruentzig decades ago . Interventionalists continue to perform angiography at the procedure table, standing under heavy protective lead aprons and manually manipulating catheters under direct fluoroscopic guidance. Radiation exposure and physical hazards have always been associated with this traditional approach. However, with complex interventions and rising case volumes, interventional operators today face greater occupational risks than ever before . Efforts are underway by the Society for Cardiovascular Angiography and Interventions (SCAI) Joint Inter-Society Task Force on Occupational Hazards in the Interventional Laboratory and the Multi-Specialty Occupational Health Group to define and publicize the impact of occupational hazards and develop strategies to mitigate operator risks . This review highlights the hazards of interventional procedures and provides a glimpse at the technologies and techniques that may reduce risks to operators in the catheterization laboratory ( Table 1 ).

2

Orthopedic & ergonomic hazards

Long hours of standing and heavy lead aprons can take a significant physical toll on the interventional cardiologist. Musculoskeletal back pain and spinal disc disease, termed “interventionalists’ disc disease”, are common orthopedic complications . Although an early questionnaire study failed to associate lead apron use with new-onset back pain among interventional radiologists, more recent studies have documented an alarming prevalence of occupational orthopedic problems associated with angiography . In a 1997 multispecialty survey of physicians, 53% of interventional cardiologists reported they had been treated for neck or back pain, a rate substantially higher than that of orthopedic surgeons, rheumatologists, and the general population . Compared to other physician groups surveyed, cardiologists reported higher caseloads and longer hours wearing personal protective equipment. Interventional cardiologists were significantly more likely to have cervical disc disease and multiple spinal levels of disc involvement, and were nearly twice as likely to miss work due to orthopedic complaints as other physician groups. In a more recent survey of interventional cardiologists, 42% reported back pain and spine problems associated with years of heavy caseloads, with 87% of respondents performing > 300 procedures per year and 51% performing > 500 cases per year . Among those with spinal complaints, 70% reported lumbosacral complaints, 40% cited cervical disc disease, and over one third missed work due to their symptoms. Musculoskeletal complaints related to the hips, knees, or ankles were reported in one quarter of all respondents. Interventionalists with more than 20 years of experience reported the highest rates of back pain, with spinal disease in nearly 60%. There was no significant correlation between annual caseload and rates of orthopedic disease.

Heavy personal protective equipment for radiation safety and poor ergonomics are implicated as the major orthopedic hazards in the catheterization laboratory. Protective lead can weigh up to 10-lb and the heaviest aprons can generate intervertebral disc space pressures as high as 300 lb/square inch . Two-piece protective garments in a skirt-vest configuration may reduce loading pressures on the cervical and thoracic spine, but no studies have directly evaluated rates of orthopedic complications by apron design. Thinner and lighter lead-free aprons have been developed using proprietary mixtures of tin, barium, bismuth, tungsten, and other elements in attempts to improve operator comfort . Garments, thyroid collars, and caps composed of barium and bismuth bi-layers offer radiation dose attenuation equivalent to a 0.5 mm thickness lead shield with as much as a 40% reduction in weight . Less conventional solutions such as rolling or ceiling-mounted “weightless” aprons may also reduce pressures applied to the spine, but are not convenient for free movement and are not common in clinical practice .

Improvements in ergonomics may also mitigate orthopedic risks. Proper table height and positioning catheterization laboratory displays at eye level in front of the operator may help maintain the spine in a neutral position. Placement of equipment controls and supplies near the operator can reduce unnecessary reaching, bending, and torsion. Additional studies are necessary to quantify the benefits of improved ergonomics in the catheterization laboratory.

Increasing physician workloads have also substantially impacted orthopedic hazards. Rising caseloads have led many interventionalists to spend more time in the catheterization laboratory, often performing multiple complex cases in a single day. The thousands of hours of fluoroscopy can take an enormous physical toll on high volume interventionalists. Despite recognition of the orthopedic risks, strenuous conditions in the catheterization laboratory continue to cause chronic musculoskeletal pain and missed workdays .

2

Orthopedic & ergonomic hazards

Long hours of standing and heavy lead aprons can take a significant physical toll on the interventional cardiologist. Musculoskeletal back pain and spinal disc disease, termed “interventionalists’ disc disease”, are common orthopedic complications . Although an early questionnaire study failed to associate lead apron use with new-onset back pain among interventional radiologists, more recent studies have documented an alarming prevalence of occupational orthopedic problems associated with angiography . In a 1997 multispecialty survey of physicians, 53% of interventional cardiologists reported they had been treated for neck or back pain, a rate substantially higher than that of orthopedic surgeons, rheumatologists, and the general population . Compared to other physician groups surveyed, cardiologists reported higher caseloads and longer hours wearing personal protective equipment. Interventional cardiologists were significantly more likely to have cervical disc disease and multiple spinal levels of disc involvement, and were nearly twice as likely to miss work due to orthopedic complaints as other physician groups. In a more recent survey of interventional cardiologists, 42% reported back pain and spine problems associated with years of heavy caseloads, with 87% of respondents performing > 300 procedures per year and 51% performing > 500 cases per year . Among those with spinal complaints, 70% reported lumbosacral complaints, 40% cited cervical disc disease, and over one third missed work due to their symptoms. Musculoskeletal complaints related to the hips, knees, or ankles were reported in one quarter of all respondents. Interventionalists with more than 20 years of experience reported the highest rates of back pain, with spinal disease in nearly 60%. There was no significant correlation between annual caseload and rates of orthopedic disease.

Heavy personal protective equipment for radiation safety and poor ergonomics are implicated as the major orthopedic hazards in the catheterization laboratory. Protective lead can weigh up to 10-lb and the heaviest aprons can generate intervertebral disc space pressures as high as 300 lb/square inch . Two-piece protective garments in a skirt-vest configuration may reduce loading pressures on the cervical and thoracic spine, but no studies have directly evaluated rates of orthopedic complications by apron design. Thinner and lighter lead-free aprons have been developed using proprietary mixtures of tin, barium, bismuth, tungsten, and other elements in attempts to improve operator comfort . Garments, thyroid collars, and caps composed of barium and bismuth bi-layers offer radiation dose attenuation equivalent to a 0.5 mm thickness lead shield with as much as a 40% reduction in weight . Less conventional solutions such as rolling or ceiling-mounted “weightless” aprons may also reduce pressures applied to the spine, but are not convenient for free movement and are not common in clinical practice .

Improvements in ergonomics may also mitigate orthopedic risks. Proper table height and positioning catheterization laboratory displays at eye level in front of the operator may help maintain the spine in a neutral position. Placement of equipment controls and supplies near the operator can reduce unnecessary reaching, bending, and torsion. Additional studies are necessary to quantify the benefits of improved ergonomics in the catheterization laboratory.

Increasing physician workloads have also substantially impacted orthopedic hazards. Rising caseloads have led many interventionalists to spend more time in the catheterization laboratory, often performing multiple complex cases in a single day. The thousands of hours of fluoroscopy can take an enormous physical toll on high volume interventionalists. Despite recognition of the orthopedic risks, strenuous conditions in the catheterization laboratory continue to cause chronic musculoskeletal pain and missed workdays .

3

Infectious hazards

Blood-borne pathogens pose an important but often overlooked risk to interventionalists and catheterization laboratory staff. Despite an increased awareness of risks, needle-stick and sharps injuries are widely prevalent in medicine . Percutaneous and vascular procedures that require routine use of needles and sharps are associated with a needle-stick injury rate of 0.6% and a glove perforation rate of 1% . A vast majority of interventional radiologists report at least one percutaneous injury during their careers, and 38% reported a sharps injury within the prior year . Accidental exposures can transmit blood-borne pathogens to the interventional operator, including hepatitis B virus (HBV), hepatitis C virus (HCV), and the human immunodeficiency virus (HIV). HBV is associated with the highest rates of occupational infection following parenteral exposure (19%–37%), while HCV is associated with a somewhat lower risk of transmission (1.9%) . Despite very low rates of HIV seroconversion following exposure (0.3%), percutaneous injuries remain the most common route of transmission in cases of occupationally acquired HIV . In light of infectious risks, all laboratory personnel should follow universal precautions and wear appropriate barrier protection to avoid skin and mucous membrane exposures. Safe sharps handling and proper sharps disposal should be standard practice . Recapping of used sharps should be strongly discouraged, as this practice was implicated in 20% of percutaneous injuries reported in a national survey of interventional radiologists . While the risk of pathogen transmission is low overall, percutaneous injuries and exposure to blood should be avoided at all costs. Airborne pathogens, most notably mycobacterium tuberculosis (MTB), also pose an infectious threat to staff in the catheterization laboratory, and appropriate respiratory precautions should be taken when active disease is suspected.

4

Hazards of radiation exposure

Exposure of medical personnel to ionizing radiation in the catheterization laboratory is of major concern . Radiation is an environmental pollutant with a linear, dose dependent risk and without evidence of a minimum safety threshold . Ionizing radiation has stochastic and deterministic effects on human tissues. Stochastic, or probabilistic, injuries typically have delayed effects and occur in proportion to the cumulative radiation exposure over time. Deterministic radiation injuries result from irradiated cell death and organ dysfunction when exposure exceeds a threshold dose. Common deterministic injuries include radiation-induced skin damage and the development of lens opacities. Stochastic radiation injuries are predominantly malignancies of the skin, GI tract, nervous system and thyroid gland .

5

Radiation-induced malignancy

Interventional cardiologists have among the highest radiation exposures of all health professionals. Recent work on the molecular effects of chronic radiation exposure from clinical practice has sobering implications. Interventional cardiologists develop somatic DNA damage and chromosomal abnormalities, as measured in vitro by micronuclei frequencies in dividing peripheral blood cells, at a higher rate than clinical cardiologists. The frequency of micronuclei correlates with the number of years of catheterization laboratory experience among interventionalists, but not with the number of years of practice among clinical cardiologists . Other molecular effects include increased lymphocyte caspase-3 activity in interventionalists compared to healthy, unexposed controls. This cellular adaptation may predispose to apoptotic induction following DNA damage from chronic radiation exposure and may serve as a protective mechanism against the cellular proliferation of potentially malignant cells .

Radiation-induced malignancy remains one of the most feared long-term occupational risks of fluoroscopy, despite the limited data validating these concerns. Early epidemiological studies of occupational radiation exposure in medicine prior to 1950 identified an excess risk of death from cancer, with increased rates of leukemia, skin and breast malignancies . Since the mid-20th century, average annual occupational radiation dose estimates have declined dramatically. Based on the limited data available from more modern epidemiological studies, occupational radiation exposure is no longer consistently associated with an higher risk of cancer .

Despite the common use of lead apron shielding, the brain remains one of the most exposed organs during interventional procedures, and is the most feared site of malignancy . Gliomas, the most common primary brain tumors in adults, are thought to arise from replicating neural stem cells, oligodendrocyte progenitor cells, and de-differentiated mature neural cells . Although the molecular pathogenesis remains uncertain, previous exposure to ionizing radiation is an established risk factor for nervous system tumors at doses less than 1 Sv — the equivalent of 10,000 chest X-rays or 63 coronary angiograms . Case–control and cohort studies seeking to link brain malignancies and occupational radiation exposure have yielded conflicting results . More recent case reports of interventionalists with left hemisphere brain malignancies have fueled ongoing safety concerns, since operators typically receive higher levels of ionizing radiation exposure to the left side of their bodies.

Despite established stochastic radiation risks at high doses, evidence for occupational radiation-induced cancer from fluoroscopy in the modern era remains circumstantial and inconclusive. The lifetime risks of cancer among interventional cardiologists remain uncertain and will require further study.