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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Up to 50% of people with PAD may have no symptoms. Symptoms of PAD in the legs and feet are generally divided into 2 categories:
1. Intermittent claudication—pain in muscles when walking or using the affected muscles that is relieved by resting those muscles. This is due to the unmet oxygen demand in muscles with use in the setting of inadequate blood flow.
2. Critical limb ischemia, consisting of:
Medical signs of PAD in the legs, due to inadequate perfusion, include:
- Noticeable change in color – blueness, or in temperature (coolness) when compared to the other limb.
- Buerger's test can check for pallor on elevation of limb and redness (rubor) on a change to a sitting position, in an assessment of arterial sufficiency.
- Diminished hair and nail growth on affected limb and digits
PAD in other parts of the body depends on the organ affected. Renal artery stenosis can cause renovascular hypertension.
Carotid artery disease can cause strokes and transient ischemic attacks.
Peripheral artery disease (PAD) is a narrowing of the arteries other than those that supply the heart or the brain. When narrowing occurs in the heart, it is called coronary artery disease, while, in the brain, it is called cerebrovascular disease. Peripheral artery disease most commonly affects the legs, but other arteries may also be involved. The classic symptom is leg pain when walking which resolves with rest, known as intermittent claudication. Other symptoms including skin ulcers, bluish skin, cold skin, or poor nail and hair growth may occur in the affected leg. Complications may include an infection or tissue death which may require amputation; coronary artery disease, or stroke. Up to 50% of cases of PAD are without symptoms.
The main risk factor is cigarette smoking. Other risk factors include diabetes, high blood pressure, and high blood cholesterol. The underlying mechanism is usually atherosclerosis. Other causes include artery spasm. PAD is typically diagnosed by finding an ankle-brachial index (ABI) less than 0.90, which is the systolic blood pressure at the ankle divided by the systolic blood pressure of the arm. Duplex ultrasonography and angiography may also be used. Angiography is more accurate and allows for treatment at the same time; however, it is associated with greater risks.
It is unclear if screening for disease is useful as it has not been properly studied. In those with intermittent claudication from PAD, stopping smoking and supervised exercise therapy improves outcomes. Medications, including statins, ACE inhibitors, and cilostazol also may help. Aspirin does not appear to help those with mild disease but is usually recommended in those with more significant disease. Anticoagulants such as warfarin are not typically of benefit. Procedures used to treat the disease include bypass grafting, angioplasty, and atherectomy.
In 2015 about 155 million people had PAD worldwide. In the developed world it affects about 5.3% of 45 to 50 years olds and 18.6% of 85- to 90-year-olds. In the developing world it affects 4.6% of people between the ages of 45 to 50 and 15% of people between the ages of 85 to 90. In the developed world PAD is equally common among men and women while in the developing world women are more commonly affected. In 2015 PAD resulted in about 52,500 deaths up from 16,000 deaths in 1990.
Arteriosclerotic heart disease (ASHD), is a thickening and hardening of the walls of the coronary arteries. Atherosclerosis is a potentially serious condition where arteries become clogged with fatty substances called plaques, or atheroma.
Macrovascular disease is a disease of any large ("macro") blood vessels in the body. It is a disease of the large blood vessels, including the coronary arteries, the aorta, and the sizable arteries in the brain and in the limbs.
This sometimes occurs when a person has had diabetes for an extended period of time. Fat and blood clots build up in the large blood vessels and stick to the vessel walls.
Three common macrovascular diseases are coronary disease (in the heart), cerebrovascular disease (in the brain), and peripheral vascular disease (in the limbs)
Macrovascular disease (macroangiopathy) refers to atherosclerosis. Atherosclerosis is a form of arteriosclerosis (thickening and hardening of arterial walls), characterized by plaque deposits of lipids, fibrous connective tissue, calcium, and other blood substances. Atherosclerosis, by definition, affects only medium and large arteries (excluding arterioles).
Macrovascular disease is associated with the development of coronary artery disease, peripheral vascular disease, brain attack (stroke), and increased risk of infection. Type 2 diabetes is more closely associated with macrovascular diseases than type 1 diabetes. Peripheral vascular disease and increased risk of infection have important implications in the care of the acutely ill patient.
Typically, Mönckeberg's arteriosclerosis is not associated with symptoms unless complicated by atherosclerosis, calciphylaxis, or accompanied by some other disease. However presence of Mönckeberg's arteriosclerosis is associated with poorer prognosis. This is probably due to vascular calcification causing increased arterial stiffness, increased pulse pressure and resulting in exaggerated damage to the heart and kidneys.
Mönckeberg's arteriosclerosis, or Mönckeberg's sclerosis, also called medial calcific sclerosis or Mönckeberg medial sclerosis, is a form of arteriosclerosis or vessel hardening, where calcium deposits are found in the muscular middle layer of the walls of arteries (the tunica media). It is an example of dystrophic calcification. This condition occurs as an age-related degenerative process. However, it can occur in pseudoxanthoma elasticum and idiopathic arterial calcification of infancy as a pathological condition, as well. Its clinical significance and cause are not well understood and its relationship to atherosclerosis and other forms of vascular calcification are the subject of disagreement.
Mönckeberg's arteriosclerosis is named after Johann Georg Mönckeberg, who first described it in 1903.
Vascular disease is a class of diseases of the blood vessels – the arteries and veins of the circulatory system of the body. It is a subgroup of cardiovascular disease. Disorders in this vast network of blood vessels, can cause a range of health problems which can be severe or prove fatal.
The carotid and vertebral arteries are most commonly affected. Middle and distal regions of the internal carotid arteries are frequently involved. Patients with FMD in the carotid arteries typically present around 50 years of age. Symptoms of craniocervical involvement include headaches (mostly migraine), pulsatile tinnitus, dizziness, and neck pain, although patients are often asymptomatic. On physical examination, one may detect neurological symptoms secondary to a stroke or transient ischemic attack (TIA), a bruit over an affected artery, and diminished distal pulses. Complications of cerebrovascular FMD include TIA, ischemic stroke, Horner syndrome, or subarachnoid hemorrhage.
The main symptoms associated with renal FMD are secondary hypertension and bruits that can be heard with a stethoscope over the abdomen or flanks. Complications such as aneurysms, dissections, or occlusion of othe renal artery have been associated with renal artery FMD.
In vascular diseases, endothelial dysfunction is a systemic pathological state of the endothelium (the inner lining of blood vessels). Along with acting as a semi-permeable membrane, the endothelium is responsible for maintaining a relaxed vascular tone and low levels of oxidative stress by releasing mediators such as nitric oxide (NO), prostacyclin (PGI2) and endothelin (ET-1), and controlling local angiotensin-II activity. This allows the endothelium, specifically in the vessels of the heart, to ensure proper blood flow to and from the heart. In terms of endothelium dysfunction, nitric oxide (causes the widening of vessels; a vasodilator) is important to consider and focus on.
Endothelial dysfunction can happen as a result of many different things, including diabetes. In diabetic patients, circulating platelets can increase endothelial dysfunction by decreasing the production of nitric oxide. It can also result from increased oxidative stress (one of the causes of oxidative stress being platelets disrupting the carotid artery), hypertension, or obesity.
One of the environmental factors that can also lead to the development of endothelial dysfunction is smoking tobacco products. Endothelial dysfunction is a major pathophysiological mechanism that leads towards coronary artery disease, and other atherosclerotic diseases.
Some people develop an initial "inflammatory phase" characterized by systemic illness with signs and symptoms of malaise, fever, night sweats, weight loss, joint pain, fatigue, and fainting. Fainting may result from subclavian steal syndrome or carotid sinus hypersensitivity. There is also often anemia and marked elevation of the ESR or C-reactive protein (nonspecific markers of inflammation). The initial "inflammatory phase" is often followed by a secondary "pulseless phase". The "pulseless phase" is characterized by vascular insufficiency from intimal narrowing of the vessels manifesting as arm or leg claudication, renal artery stenosis causing hypertension, and neurological manifestations due to decreased blood flow to the brain.
Of note is the function of renal artery stenosis in the causation of high blood pressure: Normally perfused kidneys produce a proportionate amount of a substance called renin. Stenosis of the renal arteries causes hypoperfusion (decreased blood flow) of the juxtaglomerular apparatus, resulting in exaggerated secretion of renin, and high blood levels of aldosterone, eventually leading to water and salt retention and high blood pressure. The neurological symptoms of the disease vary depending on the degree; the nature of the blood vessel obstruction; and can range from lightheadedness to seizures (in severe cases). One rare, important feature of the Takayasu's arteritis is ocular involvement in form of visual field defects, vision loss, or retinal hemorrhage. Some individuals with Takayasu's arteritis may present with only late vascular changes, without a preceding systemic illness. In the late stage, weakness of the arterial walls may give rise to localized aneurysms. As with all aneurysms, the possibility of rupture and vascular bleeding is existent and requires monitoring. In view of the chronic process and good collateral development, Raynaud's phenomenon or digital gangrene are very rare in Takayasu arteritis. A rare complication of this condition are coronary artery aneurysms.
There are several types of vascular disease, (which is a subgroup of cardiovascular disease), the signs and symptoms depend on which type, among them are:
- Erythromelalgia - a rare peripheral vascular disease where syndromes includes burning pain, increased temperature, erythema and swelling, of mainly the hands and feet are affected.
- Peripheral artery disease – happens when atheromatous plaques build up in the arteries that supply blood to the arms and legs, plaque causes the arteries to narrow or become blocked.
- Renal artery stenosis - is the narrowing of renal arteries that carry blood to the kidneys from the aorta.
- Buerger's disease – is due to small blood vessels that inflame and swell, vessels then narrow or are blocked by blood clots.
- Raynaud's disease – a rare peripheral vascular disorder of constriction of the peripheral blood vessels, in the fingers and toes when the person is cold.
- Disseminated intravascular coagulation – a widespread activation of clotting in the smaller blood vessels.
- Cerebrovascular disease–a group of vascular diseases that affect brain function.
Takayasu's arteritis (also known as Takayasu's disease, "aortic arch syndrome," "nonspecific aortoarteritis," and "pulseless disease") is a form of large vessel granulomatous vasculitis with massive intimal fibrosis and vascular narrowing, most commonly affecting often young or middle-age women of Asian descent, though anyone can be affected. It mainly affects the aorta (the main blood vessel leaving the heart) and its branches, as well as the pulmonary arteries. Females are about 8–9 times more likely to be affected than males.
Those with the disease often notice symptoms between 15 and 30 years of age. In the Western world, atherosclerosis is a more frequent cause of obstruction of the aortic arch vessels than Takayasu's arteritis. Takayasu's arteritis is similar to other forms of vasculitis, including giant cell arteritis which typically affects older individuals. Due to obstruction of the main branches of the aorta, including the left common carotid artery, the brachiocephalic artery, and the left subclavian artery, Takayasu's arteritis can present as pulseless upper extremities (arms, hands, and wrists with weak or absent pulses on the physical examination) which may be why it is also commonly referred to as the "pulseless disease." Involvement of renal arteries may lead to a presentation of renovascular hypertension.
Thrombotic Storm has been seen in individuals of all ages and races. The initial symptoms of TS present in a similar fashion to the symptoms experienced in deep vein thrombosis. Symptoms of a DVT may include pain, swelling and discoloration of the skin in the affected area. As with DVTs patients with TS may subsequently develop pulmonary emboli. Although the presentation of TS and DVTs are similar, TS typically progresses rapidly, with numerous clots occurring within a short period of time. After the formation of the initial clot a patient with TS typically begins a “clotting storm” with the development of multiple clots throughout the body. Rapid progression within a short period of time is often seen, affecting multiple organs systems. The location of the clot is often unusual or found in a spot in the body that is uncommon such as the dural sinus. Patients tend to respond very well to anticoagulation such as coumadin or low molecular weight heparin but may become symptomatic when treatment is withheld.
While the key clinical characteristics of thrombotic storm are still being investigated, it is believed that the clinical course is triggered by a preexisting condition, known as a hypercoagulable state. These can include such things as pregnancy, trauma or surgery. Hypercoagulable states can be an inherited or acquired risk factor that then serves as a trigger to initiate clot formation. However, in a subset of patient with TS a trigger cannot be identified. Typically people with TS will have no personal or family history of coagulations disorders.
Blood clots are a relatively common occurrence in the general population and are seen in approximately 1-2% of the population by age 60. Typically blood clots develop in the deep veins of the lower extremities, deep vein thrombosis (DVT) or as a blood clot in the lung, pulmonary embolism (PE). A very small number of people who develop blood clots have a more serious and often life-threatening condition, known as Thrombotic Storm (TS). TS is characterized by the development of more than one blood clot in a short period of time. These clots often occur in multiple and sometimes unusual locations in the body and are often difficult to treat. TS may be associated with an existing condition or situation that predisposes a person to blood clots such as injury, infection, or pregnancy. In many cases a risk assessment will identify interventions that will prevent the formation of blood clots.
While the mechanism or pathogenesis is not completely understood mostly due to its rarity, the medical community has developed a new interest in learning more about this syndrome. Dr. Craig S. Kitchens first described TS in six case studies. In these cases he described a collection of similar features observed in six patients, suggesting this may be accounted for by a new syndrome.
The gold standard for measuring endothelial function is angiography with acetylcholine injection. Previously, this was not done outside of research because of the invasive and complex nature of the procedure. As mentioned above, the use of acetylcholine injections to test vasodilation is now safely used for procedures where arterial catheterization is employed (this method is less frequently used though, so overall acetylcholine is not used very often in this way).
A noninvasive method to measure endothelial dysfunction is % Flow Mediated Dilation (FMD) as measured by Brachial Artery Ultrasound Imaging (BAUI). Current measurements of endothelial function via FMD vary due to technical and physiological factors. For example, FMD is largely affected by hormones, especially for women. FMD values can differ for the same woman if she is in different phases of her menstrual cycle during the time of measurement. When using this technique on people who suffer from things like heart failure, renal failure, or hypertension, their increased sympathetic tone can often falsify the results. Furthermore, a negative correlation between percent flow mediated dilation and baseline artery size is recognised as a fundamental scaling problem, leading to biased estimates of endothelial function. For research on FMD an ANCOVA approach to adjusting FMD for variation in baseline diameter is more appropriate. Another challenge of FMD is variability across centers and the requirement of highly qualified technicians to perform the procedure.
A non-invasive, FDA-approved device for measuring endothelial function that works by measuring Reactive Hyperemia Index (RHI) is Itamar Medical's EndoPAT™. It has shown an 80% sensitivity and 86% specificity to diagnose coronary artery disease when compared against the gold standard, acetylcholine angiogram. This results suggests that this peripheral test reflects the physiology of the coronary endothelium. Endopat has been tested in several clinical trials at multiple centers (including major cohort studies such as the Framingham Heart Study, the Heart SCORE study, and the Gutenberg Health Study). The results from clinical trials have shown that EndoPAT™ is useful for risk evaluation, stratification and prognosis of getting major cardiovascular events (MACE).
Since NO maintains low tone and high compliance of the small arteries at rest a reduction of age-dependent small artery compliance is a marker for endothelial dysfunction that is associated with both functional and structural changes in the microcirculation that are predictive of subsequent morbid events Small artery compliance or stiffness can be assessed simply and at rest and can be distinguished from large artery stiffness by use of pulsewave analysis with the CV Profilor.
Prognosis is generally poor for all forms of Diabetic angiopathy, as symptomatology is tied to the advancement of the underlying pathology i.e. the early-stage patient displays either non-specific symptoms or none at all.
"Diabetic dermopathy" is a manifestation of diabetic angiopathy. It is often found on the shin.
There is also Neuropathy; also associated with diabetes mellitus; type 1 and 2.
Diabetic angiopathy is a form of angiopathy associated with diabetic complications. While not exclusive, the two most common forms are Diabetic retinopathy and Diabetic nephropathy, whose pathophysiologies are largely identical.
There is a recurrent acute and chronic inflammation and thrombosis of arteries and veins of the hands and feet. The main symptom is pain in the affected areas, at rest and while walking (claudication). The impaired circulation increases sensitivity to cold. Peripheral pulses are diminished or absent. There are color changes in the extremities. The colour may range from cyanotic blue to reddish blue. Skin becomes thin and shiny. Hair growth is reduced. Ulcerations and gangrene in the extremities are common complications, often resulting in the need for amputation of the involved extremity.
The eyes may show retinal hemorrhage or an exudate. Papilledema must be present before a diagnosis of malignant hypertension can be made. The brain shows manifestations of increased intracranial pressure, such as headache, vomiting, and/or subarachnoid or cerebral hemorrhage. Patients will usually suffer from left ventricular dysfunction. The kidneys will be affected, resulting in hematuria, proteinuria, and acute renal failure. It differs from other complications of hypertension in that it is accompanied by papilledema. This can be associated with hypertensive retinopathy.
Other signs and symptoms can include:
- Chest pain
- Arrhythmias
- Headache
- Epistaxis
- Dyspnea
- Faintness or vertigo
- Severe anxiety
- Agitation
- Altered mental status
- Paresthesias
- Vomiting
Chest pain requires immediate lowering of blood pressure (such as with sodium nitroprusside infusions), while urgencies can be treated with oral agents, with the goal of lowering the mean arterial pressure (MAP) by 20% in 1–2 days with further reduction to "normal" levels in weeks or months. The former use of oral nifedipine, a calcium channel blocker, has been strongly discouraged as it has led to excessive falls in blood pressure with serious and fatal consequences.
Sometimes, the term hypertensive emergency is also used as a generic term, comprising both hypertensive "emergency", as a specific term for a serious and urgent condition of elevated blood pressure, and hypertensive urgency, as a specific term of a less serious and less urgent condition (the terminology hypertensive "crisis" is usually used in this sense).
Thromboangiitis obliterans, also known as Buerger disease (English , German ), is a recurring progressive inflammation and thrombosis (clotting) of small and medium arteries and veins of the hands and feet. It is strongly associated with use of tobacco products, primarily from smoking, but is also associated with smokeless tobacco.
Essential hypertension (also called primary hypertension or idiopathic hypertension) is the form of hypertension that by definition has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients, it tends to be familial and is likely to be the consequence of an interaction between environmental and genetic factors. Prevalence of essential hypertension increases with age, and individuals with relatively high blood pressure at younger ages are at increased risk for the subsequent development of hypertension.
Hypertension can increase the risk of cerebral, cardiac, and renal events.
A recent classification recommends blood pressure criteria for defining normal blood pressure, prehypertension, hypertension (stages I and II), and isolated systolic hypertension, which is a common occurrence among the elderly. These readings are based on the average of seated blood pressure readings that were properly measured during 2 or more office visits. In individuals older than 50 years, hypertension is considered to be present when a person's blood pressure is consistently at least 140 mmHg systolic or 90 mmHg diastolic. Patients with blood pressures over 130/80 mmHg along with Type 1 or Type 2 diabetes, or kidney disease require further treatment.
Resistant hypertension is defined as the failure to reduce blood pressure to the appropriate level after taking a three-drug regimen. Guidelines for treating resistant hypertension have been published in the UK, and US.
The term hypertensive emergency is primarily used as a specific term for a hypertensive crisis with a diastolic blood pressure greater than or equal to 120 mmHg or systolic blood pressure greater than or equal to 180 mmHg. Hypertensive emergency differs from hypertensive crisis in that, in the former, there is evidence of acute organ damage.
Signs of familial dysbetaproteinemia include xanthoma striatum palmare (orange or yellow discoloration of the palms) and tuberoeruptive xanthomas over the elbows and knees. The disease leads to premature atherosclerosis and therefore a possible early onset of coronary artery disease and peripheral vascular disease leading to a heart attack, i.e. myocardial infarction, chest pain on exercise, i.e. angina pectoris or stroke in young adults or middle aged patients.