An ankle-brachial index (ABI) that suggests increased risk of myocardial infarction would be:
There is increasing interest in the use of the ankle-brachial index (ABI) to evaluate patients at risk for cardiovascular events. An ABI less than 0.9 correlates with increased risk of myocardial infarction and indicates significant, although perhaps asymptomatic, underlying peripheral vascular disease.
All of the following are correct regarding abdominal aortic aneurysm (AAA) rupture EXCEPT:
Despite more than 50,000 patients undergoing elective repair of abdominal aortic aneurysm (AAA) each year in the United States, approximately 15,000 patients die annually as a result of ruptured aneurysm, making it the l0th leading cause of death for men. The rupture risk is quite low below 5.5 cm and begins to rise exponentially thereafter. This size can serve as an appropriate threshold for recommending elective repair provided one's surgical mortality is below 5%. For each size strata, however, women appear to be at higher risk for rupture than men, and a lower threshold of 4.5 to 5.0 cm may be reasonable in good-risk patients. Overall mortality of AAA rupture is 71 to 77%, which includes all out-of-hospital and in-hospital deaths, as compared with 2 to 6% for elective open surgical repair. Nearly half of all patients with ruptured AAA will die before reaching the hospital. For the remainder, surgical mortality is 45 to 50% and has not substantially changed in the past 30 years.
The compartment most commonly affected in a lower leg compartment syndrome is the:
The most commonly affected compartment is the anterior compartment in the leg. Numbness in the web space between the first and second toes is diagnostic due to compression of the deep peroneal nerve. Compartment pressure is measured by inserting an arterial line into the compartment and recording the pressure. Although controversial, pressures greater than 20 mm Hg are an indication for fasciotomy.
Magnetic resonance angiography (MRA) is contraindicated in the following patient groups EXCEPT those with:
Magnetic resonance angiography (MRA) has the advantage of not requiring iodinated contrast agents to provide vessel opacification (Fig. below). Gadolinium is used as a contrast agent for MRA studies, and because it is generally not nephrotoxic, it can be used in patients with elevated creatinine. MRA is contraindicated in patients with pacemakers, defibrillators, spinal cord stimulators, intracerebral shunts, cochlear implants, and cranial clips. Patients with claustrophobia may require sedation to be able to complete the test. The presence of metallic stents causes artifacts and signal drop-out; however, these can be dealt with using alternations in image acquisition and processing. Nitinol stents produce minimal artifact. Compared to other modalities, MRA is relatively slow and expensive. However, due to its noninvasive nature and decreased nephrotoxicity, MRA is being used more frequently for imaging vasculature in various anatomic distributions.
Magnetic resonance angiogram (MRA) of aortic arch and carotid arteries. This study can provide a three-dimensional analysis of vascular structure such as aortic arch branches, carotid and vertebral arteries.
The preferred procedure for treatment of typical occlusive disease of the aorta and both iliac arteries is:
In most cases, aortobifemoral bypass is performed because patients usually have disease in both iliac systems. Although one side may be more severely affected than the other, progression does occur, and bilateral bypass does not complicate the procedure or add to the physiologic stress of the operation. Aortobifemoral bypass reliably relieves symptoms, has excellent long-term patency (approximately 70-80% at 10 years), and can be completed with a tolerable peri operative mortality (2-3%).
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