Study Guide for Final Exam

Study Guide for Final Exam Abdominal aortic aneurysm

• Know the causes of an abdominal aortic aneurysm. P493

proposed causes of AAA include atherosclerosis, inflammation, mycotic infection, inheritable connective tissue disorders (Marfan syndrome, type IV Ehlers-Danlos syndrome), and trauma.atherosclerosis has been considered the most common cause of AAA and the known cause in 25% of all AAA.

• Understand risk factors for abdominal aortic aneurysm. P494

Development of AAA: Atherosclerotic vascular disease, white race, male gender, advanced age, HTN, smoking, COPD, history of hernias, family history of AAA, and presence of other aneurysms.Hypercholesterolemia AAA expansion: Advanced age, Severe cardiac disease, Previous stroke, Tobacco use, Cardiac or renal transplant.AAA rupture: Female gender, Low FEV1, Larger initial AAA diameter, Higher mean blood pressure, Current tobacco use, Cardiac or renal transplant, Critical wall stress–wall strength relationship AAA is an important clinical diagnosis because it is associated with considerable risk of rupture and death as the aneurysm enlarges to a diameter of more than 5.0cm (1.96 inches).Evidence suggests that the high prevalence of AAA in patients with COPD may be related to medications (oral steroids) and coexisting diseases rather than to a common pathway of pathogenesis involving plasma elastase or α1-antitrypsin deficiency AAA and elevated homocysteine plasma levels.AAA represent 75% of aortic aneurysms

• Know the symptoms of an abdominal aortic aneurysm.

AAA may cause symptoms as a result of the pressure on surrounding structures, about 75% are asymptomatic at initial diagnosis.

Symptoms:

Symptomatic aneurysms increase in number after the age of 70years.In thin patients, a supine abdominal examination may readily show a pulsatile abdominal mass,

Inflammatory AAAs may be manifested with chronic abdominal pain or back pain and, sometimes, ureteral obstruction Microembolic infarcts in the lower extremity of a patient with easily palpable pedal pulses may suggest either abdominal or popliteal aneurysm. Embolization of mural thrombus from an abdominal aneurysm may be seen with acute limb ischemia caused by femoral or popliteal occlusion.Symptom and sign of a ruptured AAA classic diagnostic triad of ruptured AAA is hypotension (42%), pulsatile abdominal mass (91%), and abdominal pain (58%) or back pain (70%). The triad is encountered in only 50% of patients with a ruptured AAA. Ruptured AAAs should be suspected in any patient who comes in with complaints of hypotension and atypical abdominal or back pain symptoms

• What is a Saccular Abdominal Aneurysm?

Saccular aneurysm is an asymmetric weakness or bleb on the side of the aorta; these defects result from trauma or an internal wall defect caused by an ulcer.Fusiform aneurysm is a symmetric weakness of the entire circumference of the aorta that produces a bulge.

• What are the risks for abdominal aortic aneurysm?

AAA is an important clinical diagnosis because it is associated with considerable risk of rupture and death as the aneurysm enlarges to a diameter of more than 5.0cm (1.96 inches)

Diagnostic Testing for CAD

• Why is CT imaging limited in women? P492

Single-photon emission CT imaging is technically limited in women because breast tissue and smaller coronary artery size

• Can ischemic changes on an ECG during or after an ETT correlate to the effected artery

or arteries?

Ischemia that is confined to only the posterior and or lateral segments of the left ventricle is difficult to detect by ETT, but that does not mean that ETT cannot detect ischemia limited to these functional areas of the heart.

• What diagnostic test is used for CAD? P488

Exercise Tolerance Test- standard first-line approach to initial testing for CAD is the ETT, during which the patient (attached to a 12-lead electrocardiogram) is continuously monitored during graded exercise. The bicycle and treadmill are the two most often used.The primary goal of the ETT is to increase workload incrementally to induce ischemia or until a predetermined workload is reached.Myocardial Perfusion Imaging- MPI offers a method of visualizing blood flow to the heart by injection of a radioactive cardiac-specific tracer. This improves the diagnostic accuracy of a stress test because it gives another method of detecting perfusion defects aside from measuring ST depression on the electrocardiogram.thallium chloride Tl 201 and technetium Tc 99m sestamibi are the radiopharmaceutical agents used for the detection of CAD in MPI.MPI such be used when baseline ECG abnormality that would interfere with measurement of stress-induced ST-segment changes, such as left ventricular hypertrophy, bundle branch blocks, and digoxin use. MPI is also a useful tool for use with high-risk diabetic patients Cardiac Magnetic Resonance Imaging (MRI): Cardiac MRI is, with further technologic refinement, anticipated to provide accurate data to distinguish between stable and unstable plaque and to assist with quantifying CAD, replacing the diagnostic cardiac catheterization Exercise Echocardiography- echocardiographic imaging enhances the sensitivity and specificity of CAD detection to an extent comparable to that provided by nuclear techniques.1 The 2DE evidence for ischemia includes an abnormal left ventricular ejection fraction (LVEF) response to exercise or the development of regional wall motion abnormalities. The exercise is performed with a bicycle or treadmill, and dobutamine is the most common pharmacologic agent used simultaneously with the echocardiography imaging. The image quality may be enhanced by the injection of echogenic microbubbles.

• Understand the coronary flow related to CAD.

CAD exists when coronary arteries are narrowed by atherosclerotic plaque formation, plaque rupture, or spasm. This narrowing impedes coronary blood flow, resulting in hypoperfusion of the myocardium.The hypoperfusion produces first diastolic, and then systolic dysfunction, with characteristic signs and symptoms, including chest pain.Typical ECG changes of ischemia result, although the ST-segment and T-wave changes that are central to demonstration of ischemia occur relatively late in the ischemic cascade.

• What is the best reason to add a Doppler flow studies during an echocardiogram study?

The Doppler portion of the examination is able to provide an assessment of the outflow gradient that closely approximates that obtained by cardiac catheterization. By combining Doppler ultrasonography and echocardiography, the examiner may make a reasonable calculation of the aortic valve area. Thickened, calcified, and immobile leaflets are readily noted by transthoracic two-dimensional echocardiography.Detect and evaluate blood shunting from a septal defect (Your best response for this specific case, however, would be that Doppler Flow studies would detect and evaluate blood shunting from a septal defect.)

• What defines a positive exercise echocardiogram?

A positive exercise echocardiogram is defined by stress- induced decrease in regional wall motion, decreased wall thickening, or regional compensatory hyperkinesis Induced decrease in regional wall motion (Induced decrease in regional wall motion would be included in defining a positive exercise echocardiogram. Wall thickening would not traditionally occur in a positive test and hyperkinesis, not hypokinesis, generally occurs in a positive test.)

• What changes would you see during an ETT that are highly predictive of CAD? P489

On the other hand, if there is evidence of ischemia (typical angina, ischemic ST changes) before the patient's target heart rate is reached, the test is considered strongly predictive of significant CAD.A second important predictor of more advanced CAD is exercise-induced hypotension (i.e., a fall in systolic blood pressure of at least 20mm Hg at any point during exercise).