Arterial Diseases

Thoracic aortic aneurysm (TAA) is the abnormal dilation of a segment of the thoracic aorta, usually the ascending aorta. Most TAAs are due to degenerative aortic disorders, commonly in patients > 65 years of age. Genetic TAAs account for 20% of cases and are frequently found in younger patients. Most TAAs are asymptomatic (incidentally found in imaging) but could present with symptoms from its effects on surrounding structures. Aortic rupture is a life-threatening emergency. Among diagnostic imaging studies, computed tomography (CT) angiography is the most widely utilized. In asymptomatic cases, aortic expansion is monitored. Operative repair is recommended for symptomatic TAAs and increasing aortic diameter (criteria varies with location and underlying condition).

Renal artery stenosis (RAS) is the narrowing of one or both renal arteries, usually caused by atherosclerotic disease or by fibromuscular dysplasia. If the stenosis is severe enough, the stenosis causes decreased renal blood flow, which activates the renin-angiotensin-aldosterone system (RAAS) and leads to renovascular hypertension (RVH), which only accounts for a small fraction of all cases of hypertension. Renovascular hypertension can be associated with abdominal bruits, renal insufficiency, or progressive renal atrophy. Diagnosis is by clinical presentation followed by imaging studies, including duplex ultrasonography, magnetic resonance angiography (MRA), computed tomography angiography (CTA), and sometimes catheter-based angiography. Revascularization is usually reserved for cases in which medical therapy has failed.

Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, medium-sized angiopathy due to fibroplasia of the vessel wall. The condition leads to complications related to arterial stenosis, aneurysm, or dissection. The clinical presentation can differ depending on which arteries are affected, but may include secondary hypertension from renal artery stenosis (RAS), neurologic deficits from cerebrovascular involvement, claudication due to limb involvement, and intestinal angina from mesenteric artery disease. The diagnosis is confirmed with imaging, such as computed tomography with angiography. Treatment includes lifestyle modifications, antihypertensive therapy for RAS patients, and potential revascularization.

Carotid artery stenosis is a chronic atherosclerotic disease resulting in narrowing of the common and internal carotid arteries. Common risk factors include family history, advanced age, hyperlipidemia, smoking, and diabetes mellitus. Patients may present with or without symptoms of decreased cerebral perfusion. Carotid artery stenosis is commonly diagnosed via ultrasound. Management includes lifestyle modifications to control progression of atherosclerosis. Treatment is with statins, anti-hypertensive and antiplatelet agents, and, in some cases, surgical revascularization. The most serious complication of carotid artery stenosis is stroke.

Statins are competitive inhibitors of HMG-CoA reductase in the liver. HMG-CoA reductase is the rate-limiting step in cholesterol synthesis. Inhibition results in lowered intrahepatocytic cholesterol formation, resulting in up-regulation of LDL receptors and, ultimately, lowering levels of serum LDL and triglycerides. Statins can lower LDL 20%–60% (depending on their intensity) and have benefits that are cholesterol-independent (e.g., reduced vascular inflammation and atherosclerotic plaque stabilization). Indications for prescribing statins include prevention of primary or secondary cardiovascular disease in patients with dyslipidemia. The main adverse effects are transaminitis and muscle toxicity.

Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. The disorder can usually be managed with lifestyle modification and medications, but occasionally, vascular intervention or surgery are required. Age, sex, smoking, obesity, and diet are contributing factors to hypertension, which can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. Many individuals with hypertension are undiagnosed or undertreated.

Acute limb ischemia (ALI) is a major vascular emergency because of the rapid decrease in limb perfusion that causes a potential threat to limb viability. The majority of cases are caused by arterial thrombosis due to plaque progression or embolism, but ALI can also be caused by blockage of the venous drainage. The typical signs and symptoms of ALI are often referred to as the 6 Ps: pain, pallor, poikilothermia, paralysis, paresthesia, and pulselessness. The diagnosis is made on the basis of clinical findings and Doppler studies, but additional imaging may be required. Management is focused on revascularization. IV heparin is also administered. Nonviable limbs require amputation.

Hypertension, or high blood pressure, is a common disease manifesting as elevated systemic arterial pressure. Hypertension is most often asymptomatic and discovered as part of a routine physical examination, or during triage for an unrelated medical encounter. Age, gender, smoking, obesity, and diet are all contributing factors to hypertension and can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. If blood pressure cannot be controlled with lifestyle modifications, medications are employed for the management of hypertension. The 1st-line medication classes include thiazide-like diuretics, angiotensin-converting enzyme inhibitors (ACEis), angiotensin II receptor blockers (ARBs), and calcium channel blockers (CCBs). Contraindications, adverse effects, and drug-to-drug interactions are agent specific.

Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. It manifests itself as vessel stenosis and a source of thromboembolic disease. Its clinical manifestations depend on the specific vessels affected and include most notably coronary artery disease, carotid disease, and peripheral vascular disease. It is the most common primary disease of the arterial vascular system and is responsible for coronary heart disease, the leading cause of death worldwide.

Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Deep vein thrombosis (DVT) is diagnosed in > 50% of patients presenting with symptoms, in whom the lower-extremity deep-venous system is the most common source of thrombus. Some individuals are asymptomatic, but the most common presenting symptom is dyspnea. The symptoms can be acute or chronic, and diagnosis is usually based on radiographic findings. Initial management is supportive and focuses on restoring oxygenation and hemodynamic stability. Both medical (systemic anticoagulants) and interventional therapies (catheter-based approach, surgery) are used to reestablish vessel patency.

Aortic dissection occurs due to shearing stress from pulsatile pressure causing a tear in the tunica intima of the aortic wall. This tear allows blood to flow into the media, creating a “false lumen.” Aortic dissection is most commonly caused by uncontrolled hypertension. Complications arise due to partial occlusion of vital branches off the aorta and reduced blood flow to the brain, visceral organs, and extremities. Patients often present with acute, tearing chest or back pain. Computed tomography is the diagnostic modality of choice. All type A dissections (ascending aorta) are a surgical emergency due to the risk of imminent rupture. Type B dissections (descending aorta) can be managed medically with impulse control using beta-blockers and calcium channel blockers. If there is evidence of malperfusion to visceral organs or extremities, aneurysm dilation to > 5 cm, retrograde extension into the ascending aorta, or intractable pain, the patient will need evaluation for endovascular or open repair.

Peripheral artery disease (PAD) is obstruction of the arterial lumen resulting in decreased blood flow to the distal limbs. The disease can be a result of atherosclerosis or thrombosis. Patients may be asymptomatic or have progressive claudication, skin discoloration, ischemic ulcers, or gangrene. Onset may be insidious (atherosclerosis) or abrupt (thrombosis). Diagnosis is made with the clinical history, exam, and measurement of the ankle-brachial index. Imaging studies can determine the location and extent of the arterial disease. Treatment varies depending on the severity but can include lifestyle modifications, antiplatelet therapy, risk factor modifications, phosphodiesterase inhibitors, and revascularization.

Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. The most common symptoms include tachycardia, tachypnea, hypotension, altered mentation, and oliguria. Treatment measures vary depending on the suspected cause of shock and may include mechanical ventilation, IV crystalloids, vasopressors, and blood transfusion.

An aortic aneurysm is the abnormal dilation of a segment of the aorta. Abdominal aortic aneurysm is the most common aortic aneurysm, occurring frequently in the infrarenal area. Degenerative aortic disorders are the prevalent etiology, affecting patients > 60 years of age. Most aneurysms are asymptomatic, but can cause compression of surrounding structures or rupture, which is a life-threatening emergency. Diagnosis is often made by ultrasound. As aneurysmal rupture carries a high mortality rate, surveillance is recommended for asymptomatic cases to monitor aortic diameter. Elective surgery (the majority via endovascular aortic repair) is an effective way to reduce complications and aneurysm-related death. This surgery is performed based on aortic size, underlying condition, and associated symptoms.

Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Clinically significant complications may occur when blood pressure falls enough for crucial organs to become insufficiently perfused. Diagnostic studies and treatment depend on the clinical presentation and underlying conditions.