Surgical Treatment for Arterial Thrombosis and Embolism

Blood clotting (thrombosis) in a native artery or arterial bypass graft causes sudden lack of blood flow to an extremity or major organ (e.g., kidneys or intestine). Blood flow can also be suddenly interrupted if a blood clot dislodges from the heart or other central artery and gets trapped in a smaller artery “downstream” (embolism). Patients with acute arterial thrombosis or embolism usually require urgent intervention to remove the blood clot.

Surgery, using balloon-tipped catheters to remove blood clot (thrombectomy or embolectomy), is the traditional approach to treating arterial thrombosis and embolism. Although medical dissolution therapy (thrombolysis) is being used more frequently, surgery is still generally preferred when blood flow must be restored immediately to save an organ or extremity.

In 1996-97, arterial embolectomy and thrombectomy (excluding dialysis access sites) were performed at an average rate of 0.50 per 1,000 Medicare enrollees. This rate varied from 0.18 per 1,000 enrollees in the Grand Junction, Colorado hospital referral region to 0.89 per 1,000 enrollees in the hospital referral region in Mobile, Alabama. General surgeons performed most of these procedures (41%); vascular and cardiothoracic surgeons performed 31% and 27%, respectively.

Figure 6.1.

Proportion of Thrombectomy and Embolectomy Procedures Performed by Vascular, Cardiothoracic and General Surgeons (1996). Numbers of Medicare enrollees undergoing surgery by each type of surgeon are in parentheses.

Map 6.1.

Thrombectomy and Embolectomy Procedures (1996-97). Although rates of thrombectomy and embolectomy were highly variable, there was no consistent geographic pattern. Forty-two hospital referral regions had surgery rates at least 30% above the national average; (more...)

Use of Thrombolytic Therapy for Thrombosis and Embolism

Although surgery was once the only available treatment, thrombolytic therapy has become an increasingly popular alternative for treating patients with arterial thrombosis and embolism. With thrombolytic therapy, a catheter is inserted into the blood clot via a remote arterial puncture, usually in the groin. Medications that dissolve the clot are then administered. Thrombolytic therapy is preferred for more diffuse clotting, especially in smaller arteries, and when immediate, total restoration of blood flow is not required. This type of treatment may also be used for patients with blood clots in major veins (venous thrombosis).

The average rate of thrombolytic therapy for arterial and venous thrombosis (excluding dialysis access sites) was 0.45 per 1,000 Medicare enrollees. There was a substantial degree of regional variation (almost 17-fold) in rates of thrombolysis, which ranged from 0.12 per 1,000 enrollees in Greenville, South Carolina to 2.05 per 1,000 enrollees in Jackson, Tennessee. Among the hospital referral regions where rates of thrombolytic treatment were higher than 1.0 per 1,000 residents were Hinsdale, Illinois (1.14); Lafayette, Louisiana (1.08); Peoria, Illinois (1.07) and Pensacola, Florida (1.05). Regions with rates lower than the national average included Amarillo, Texas (0.13); Altoona, Pennsylvania (0.13); Kingsport, Tennessee (0.14); Winchester, Virginia (0.14) and Harlingen, Texas (0.16). Radiologists performed the large majority of thrombolytic therapy procedures (83%).

Figure 6.2.

Proportion of Thrombolytic Therapy Procedures Performed by Different Kinds of Specialists (1996). The numbers of Medicare enrollees undergoing surgery by each type of surgeon are in parentheses. Thrombolytic therapy for dialysis access sites is excluded. (more...)

Map 6.2.

Thrombolytic Therapy for Arterial and Venous Thrombosis (1996-97). Although there were no consistent geographic patterns, many hospital referral regions in the West and Southwest had rates of thrombolytic therapy at least 30% higher than the national (more...)

Surgical Treatment of Vascular Trauma

Important arteries and veins may be injured by penetrating trauma, such as knife or gunshot injuries, or by blunt trauma, most often motor vehicle accidents. In the elderly, vascular injuries often occur as complications of medical treatment, particularly coronary angiography and other invasive radiologic procedures requiring insertion of catheters in major arteries. Severe injuries require surgical treatment, which may include direct repair, closure with a patch, or replacement of a vessel segment with a venous or synthetic conduit.

In 1996-97, the average rate for repair of vascular injuries per 1,000 Medicare enrollees was 0.45. This ranged from 0.09 in Kingsport, Tennessee to 2.80 in Salinas, California. Variation in rates of repair is most likely explained by regional differences in injury rates, since there is in general little controversy about the need for surgery in vascular trauma. Board-certified vascular surgeons performed 39% of procedures for vascular trauma; general and cardiothoracic surgeons performed 34% and 26% of these procedures, respectively.

Figure 6.3.

Proportion of Procedures for Vascular Trauma Performed by Vascular, Cardiothoracic, and General Surgeons (1996). Numbers of Medicare enrollees undergoing surgery by each type of surgeon are in parentheses.

Map 6.3.

Procedures for Vascular Trauma (1996-97). Although procedure rates for vascular trauma were highly variable, there was no consistent geographic pattern.

Surgical Treatment of Varicose Veins

Varicose veins are prominent, enlarged superficial veins in the legs. Varicose veins, which usually do not cause symptoms, may be bothersome to some patients because of their unsightly appearance. In some patients, however, varicose veins cause pain, swelling, and even ulceration. Treatment options include sclerotherapy (injection therapy, used primary for small varicose veins) and external compression with support stockings. Surgical treatment involves excision through a number of small incisions. Although varicose veins most commonly develop in younger persons (particularly women after childbirth), the condition is also prevalent in the elderly.

In 1996-97, the average rate of varicose vein excision was 0.29 per 1,000 Medicare enrollees. Regional rates ranged from 0.09 per 1,000 enrollees in Charlottesville, Virginia to 1.46 per 1,000 in Des Moines, Iowa. Among hospital referral regions with rates of varicose vein excision substantially higher than the national average were San Bernardino, California (0.91); St. Petersburg, Florida (0.78); Fort Myers, Florida (0.70) and Bradenton, Florida (0.68). Regions with rates of 0.10 per 1,000 enrollees or lower included Charlottesville, Virginia, Macon, Georgia and Shreveport, Louisiana. General surgeons performed 65% of varicose vein excisions; vascular and cardiothoracic surgeons performed 23% and 11% of these procedures, respectively.

Figure 6.4.

Proportion of Varicose Vein Excisions Performed by Vascular, Cardiothoracic, and General Surgeons (1996). The numbers of Medicare enrollees undergoing surgery by each type of surgeon are in parentheses.

Map 6.4.

Varicose Vein Excision (1996-97). Although rates of varicose vein excision were highly variable, there was no consistent geographic pattern. Fifty-two hospital referral regions had surgery rates at least 30% above the national average; 76 regions had (more...)

Use of Vena Cava Filters to Prevent Pulmonary Embolism

Pulmonary embolism is a life-threatening condition in which blood clots dislodge from veins in the legs (or sometimes pelvis) and travel to the lung, where they block blood flow. Patients at highest risk for deep venous thrombosis and pulmonary embolism include patients with cancer and those who are bedridden or recovering from major surgery. To reduce the risk of pulmonary embolism, most patients with known (or at very high risk for) venous thrombosis are treated with anticoagulants (blood thinners). However, because anticoagulation is not safe for some patients at high risk of bleeding, a filter device can be placed (via a catheter in the groin or neck) in the vena cava—the main vein of the abdomen. Vena cava filters trap blood clots and prevent them from reaching the lung.

In 1996-97, the average rate of vena cava filter placement was 0.90 per 1,000 Medicare enrollees. This rate varied fourteen-fold across hospital referral regions, from 0.19 per 1,000 in Stockton, California to 2.73 per 1,000 in Akron, Ohio. Among the hospital referral regions where rates of vena cava filter placement were substantially higher than the national average were New Brunswick, New Jersey (2.55); Allentown, Pennsylvania (2.07); Philadelphia (2.07); Cleveland (1.92) and Dearborn, Michigan (1.89). Regions with relatively low rates of vena cava filter placement included San Jose, California (0.21); Waco, Texas (0.22); Eugene, Oregon (0.23); St. Cloud, Minnesota (0.23) and Grand Forks, North Dakota (0.24).

Figure 6.5.

Rates of Vena Cava Filter Placement Among Hospital Referral Regions (1996-97). Rates of vena cava filter placement ranged fourteen-fold, from 0.19 to 2.73 per 1,000 Medicare enrollees, even after adjustments for differences in the age, sex, and race (more...)

Map 6.5.

Vena Cava Filter Placement (1996-97). Hospital referral regions in the Mid-Atlantic states and southern New England were among those with high rates of vena cava filter placement. Rates were generally lower in the western half of the United States.

Specialists Performing Vena Cava Filter Placement

In the 1996 Medicare population, most vena cava filter placements were performed by radiologists (56%). However, a substantial proportion of these procedures were done by general surgeons (18%), vascular surgeons (13%), cardiothoracic surgeons (11%), and cardiologists (3%).

The proportion of vena cava filter placements performed by each specialty varied substantially among hospital referral regions. The proportion performed by general surgeons in 1996 varied from 0% in 73 regions to 78% in Sun City, Arizona. The proportion performed by vascular surgeons varied from 0% in 104 regions to 70% in Rochester, New York. The proportion performed by cardiothoracic surgeons varied from 0% in 100 regions to 92% in Harlingen, Texas. The proportion performed by cardiologists varied from 0% in 211 regions to 80% in Lubbock, Texas.

Figure 6.6.

Proportion of Vena Cava Filters Placed by Radiologists, Cardiologists, and Vascular, Cardiothoracic, and General Surgeons (1996). Numbers of Medicare enrollees undergoing procedures by each type of physician are in parentheses.

Map 6.6.

Specialty Type of Physician Performing the Plurality of Vena Cava Filter Placements (1996). Radiologists performed a plurality of these procedures in 240 hospital referral regions.

Chapter Six Table

Based on data from the 1996-97 Medicare Part B file, the table displays rates of procedures for miscellaneous vascular diseases, by hospital referral region. Rates are age, sex, and race adjusted. They do not reflect procedures performed on Medicare enrollees who were members of non-risk bearing managed care organizations. Specialty market share data for vascular trauma repair and vena cava filter placement, based on 1996 data alone, are simple proportions. Specialty market share data for thrombectomy and embolectomy, not shown in the Table, are very similar to those reported earlier for surgical bypass for lower extremity arterial occlusive disease (Chapter 4). In the large majority of regions, most thrombolytic therapy was administered by radiologists.

The Appendix on Methods describes codes used to identify these procedures, adjustment methods, and other details.

Chapter Six Table

Rates of Miscellaneous Vascular Procedures and Specialty Marketshare by Hospital Referral Region.