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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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A significant number of people with hypertrophic cardiomyopathy do not have any symptoms and will have normal life expectancies, although they should avoid particularly strenuous activities or competitive athletics, and should be screened for risk factors for sudden cardiac death. In people with resting or inducible outflow obstructions, situations that will cause dehydration or vasodilation (such as the use of vasodilatory or diuretic blood pressure medications) should be avoided. Septal reduction therapy is not recommended in asymptomatic people.
The primary goal of medications is to relieve symptoms such as chest pain, shortness of breath, and palpitations. Beta blockers are considered first-line agents, as they can slow down the heart rate and decrease the likelihood of ectopic beats. For people who cannot tolerate beta blockers, nondihydropyridine calcium channel blockers such as verapamil can be used, but are potentially harmful in people who also have low blood pressure or severe shortness of breath at rest. These medications also decrease the heart rate, though their use in people with severe outflow obstruction, elevated pulmonary artery wedge pressure, and low blood pressures should be done with caution. Dihydropyridine calcium channel blockers should be avoided in people with evidence of obstruction. For people whose symptoms are not relieved by the above treatments, disopyramide can be considered for further symptom relief. Diuretics can be considered for people with evidence of fluid overload, though cautiously used in those with evidence of obstruction. People who continue to have symptoms despite drug therapy can consider more invasive therapies. Intravenous phenylephrine (or another pure vasoconstricting agent) can be used in the acute setting of low blood pressure in those with obstructive hypertrophic cardiomyopathy who do not respond to fluid administration.
Many factors influence the time course and extent of remodeling, including the severity of the injury, secondary events (recurrent ischemia or infarction), neurohormonal activation, genetic factors and gene expression, and treatment. Medications may attenuate remodeling. Angiotensin-converting enzyme (ACE) inhibitors have been consistently shown to decrease remodeling in animal models or transmural infarction and chronic pressure overload. Clinical trials have shown that ACE inhibitor therapy after myocardial infarction leads to improved myocardial performance, improved ejection fraction, and decreased mortality compared to patients treated with placebo. Likewise, inhibition of aldosterone, either directly or indirectly, leads to improvement in remodeling. Carvedilol, a 3rd generation beta blocker, may actually reverse the remodeling process by reducing left ventricular volumes and improving systolic function. Early correction of congenital heart defects, if appropriate, may prevent remodeling, as will treatment of chronic hypertension or valvular heart disease. Often, reverse remodeling, or improvement in left ventricular function, will also be seen.
Until recently, it was generally assumed that the prognosis for individuals with diastolic dysfunction and associated intermittent pulmonary edema was better than those with systolic dysfunction. In fact, in two studies appearing in the New England Journal of Medicine in 2006, evidence was presented to suggest that the prognosis in diastolic dysfunction is the same as that in systolic dysfunction.
Despite increasing incidence of HFpEF effective inroads to therapeutics have been largely unsuccessful. Currently, recommendations for treatment are directed at symptom relief and co-morbid conditions. Frequently this involves administration of diuretics to relieve complications associated with volume overload, such as leg swelling and high blood pressure.
Commonly encountered conditions that must be treated for and have independent recommendations for standard of care include atrial fibrillation, coronary artery disease, hypertension, and hyperlipidemia. There are particular factors unique to HFpEF that must be accounted for with therapy. Unfortunately, currently available randomized clinical trials addressing the therapeutic adventure for these conditions in HFpEF present conflicting or limited evidence.
Specific aspects of therapeutics should be avoided in HFpEF to prevent the deterioration of the condition. Considerations that are generalizable to heart failure include avoidance of a fast heart rate, elevations in blood pressure, development of ischemia, and atrial fibrillation. More specific to HFpEF include avoidance of preload reduction. As patients display normal ejection fraction but reduced cardiac output they are especially sensitive to changes in preloading and may rapidly display signs of output failure. This means administration of diuretics and vasodilators must be monitored carefully.
HFrEF and HFpEF represent distinct entities in terms of development and effective therapeutic management. Specifically cardiac resynchronization, administration of beta blockers and angiotensin converting enzyme inhibitors are applied to good effect in HFrEF but are largely ineffective at reducing morbidity and mortality in HFpEF. Many of these therapies are effective in reducing the extent of cardiac dilation and increasing ejection fraction in HFrEF patients. It is unsurprising they fail to effect improvement in HFpEF patients, given their un-dilated phenotype and relative normal ejection fraction. Understanding and targeting mechanisms unique to HFpEF are thus essential to the development of therapeutics.
Randomized studies on HFpEF patients have shown that exercise improves left ventricular diastolic function, the heart's ability to relax, and is associated with improved aerobic exercise capacity. The benefit patients seem to derive from exercise does not seem to be a direct cardiac effect but rather is due to changes in peripheral vasculature and skeletal muscle, which show abnormalities in HFpEF patients.
Patients should be regularly assessed to determine progression of the condition, response to interventions, and need for alteration of therapy. Ability to perform daily tasks, hemodynamic status, kidney function, electrolyte balance, and serum natriuretic peptide levels are important parameters. Behavioral management is important in these patients and it is recommended that individuals with HFpEF avoid alcohol, smoking, and high sodium intake.
The enlargement is not permanent in all cases, and in some cases the growth can regress with the reduction of blood pressure.
LVH may be a factor in determining treatment or diagnosis for other conditions. For example, LVH causes a patient to have an irregular ECG. Patients with LVH may have to participate in more complicated and precise diagnostic procedures, such as imaging, in situations in which a physician could otherwise give advice based on an ECG.
Ventricular hypertrophy (VH) is thickening of the walls of a ventricle (lower chamber) of the heart. Although left ventricular hypertrophy (LVH) is more common, right ventricular hypertrophy (RVH), as well as concurrent hypertrophy of both ventricles can also occur.
Ventricular hypertrophy can result from a variety of conditions, both adaptive and maladaptive. For example, it occurs in what is regarded as a physiologic, adaptive process in pregnancy in response to increased blood volume; but can also occur as a consequence of ventricular remodeling following a heart attack. Importantly, pathologic and physiologic remodeling engage different cellular pathways in the heart and result in different gross cardiac phenotypes.
As previously stated, management of HFpEF is primarily dependent on the treatment of symptoms and exacerbating conditions. Currently treatment with ACE inhibitors, calcium channel blockers, beta blockers, and angiotensin receptor blockers are employed but do not have a proven benefit in HFpEF patients. Additionally, use of Diuretics or other therapies that can alter loading conditions or blood pressure should be used with caution. It is not recommended that patients be treated with phosphodiesterase-5-inhibitors or digoxin.
Antimineralocorticoid is currently recommended for patients with HFpEF who show elevated brain natriuretic peptide levels. Spironolactone is the first member of this drug class and the most frequently employed. Care should be taken to monitor serum potassium levels as well as kidney function, specifically glomerular filtration rate during treatment.
Beta blockers play a rather obscure role in HFpEF treatment but appear to play a beneficial role in patient management. There is currently a deficit of clinical evidence to support a particular benefit for HFpEF patients, with most evidence resulting from HFpEF patients' inclusion in broader heart failure trials. However, some evidence suggests that vasodilating beta blockers, such as nebivolol, can provide a benefit for patients with heart failure regardless of ejection fraction. Additionally, because of the chronotropic perturbation and diminished LV filling seen in HFpEF the bradycardic effect of beta blockers may enable improved filling, reduced myocardial oxygen demand and lowered blood pressure. However, this effect also can contribute to diminished response to exercise demands and can result in an excessive reduction in heart rate.
ACE inhibitors do not appear to improve morbidity or mortality associated with HFpEF alone. However, they are important in the management of hypertension, a significant player in the pathophysiology of HFpEF.
Angiotensin II receptor blocker treatment shows an improvement in diastolic dysfunction and hypertension that is comparable to other anti-hypertensive medication.
Generally, diastolic dysfunction is a chronic process. When this chronic condition is well tolerated by an individual, no specific treatment may be indicated. Rather, therapy should be directed at the root cause of the stiff left ventricle, with potential causes and aggravating factors like high blood pressure and diabetes treated appropriately. Conversely (as noted above), diastolic dysfunction tends to be better tolerated if the atrium is able to pump blood into the ventricles in a coordinated fashion. This does not occur in atrial fibrillation (AF), where there is no coordinated atrial activity and the left ventricle loses around 20% of its output. However, in chronic AF and in geriatric patients, AF is better tolerated and the cardiologist must choose between a stable AF at a lower rate and the risk of having an intermittent AF if he pretends to treat AF aggressively with all the thrombo-embolic risk it implies. In the same light, and also as noted above, if the atrial fibrillation persists and is resulting in a rapid heart rate, treatment must be given to slow down that rate. Usually digoxin maintains a stable rhythm. The use of a self-expanding device that attaches to the external surface of the left ventricle has been suggested, yet still awaits FDA approval. When the heart muscle squeezes, energy is loaded into the device, which absorbs the energy and releases it to the left ventricle in the diastolic phase. This helps retain muscle elasticity.
The role of specific treatments for diastolic dysfunction "per se" is as yet unclear. Diuretics can be useful, if these patients develop significant congestion, but patients must be monitored because they frequently develop hypotension.
Beta-blockers are the first-line therapy as they induce bradycardia and give time for ventricles to fill. There is some evidence that calcium channel blocker drugs may be of benefit in reducing ventricular stiffness in some cases (verapamil has the benefit lowering the heart rate). Likewise, treatment with angiotensin converting enzyme inhibitors, such as enalapril, ramipril, and many others, may be of benefit due to their effect on preventing ventricular remodeling but under control to avoid hypotension.
Left ventricular hypertrophy (LVH) is thickening of the heart muscle of the left ventricle of the heart, that is, left-sided ventricular hypertrophy.
In cardiology, ventricular remodeling (or cardiac remodeling) refers to changes in the size, shape, structure, and function of the heart. This can happen as a result of exercise (physiological remodeling) or after injury to the heart muscle (pathological remodeling). The injury is typically due to acute myocardial infarction (usually transmural or ST segment elevation infarction), but may be from a number of causes that result in increased pressure or volume, causing pressure overload or volume overload (forms of strain) on the heart. Chronic hypertension, congenital heart disease with intracardiac shunting, and valvular heart disease may also lead to remodeling. After the insult occurs, a series of histopathological and structural changes occur in the left ventricular myocardium that lead to progressive decline in left ventricular performance. Ultimately, ventricular remodeling may result in diminished contractile (systolic) function and reduced stroke volume.
Physiological remodeling is reversible while pathological remodeling is mostly irreversible. Remodeling of the ventricles under left/right pressure demand make mismatches inevitable. Pathologic pressure mismatches between the pulmonary and systemic circulation guide compensatory remodeling of the left and right ventricles. The term "reverse remodeling" in cardiology implies an improvement in ventricular mechanics and function following a remote injury or pathological process.
Ventricular remodeling may include ventricular hypertrophy, ventricular dilation, cardiomegaly, and other changes. It is an aspect of cardiomyopathy, of which there are many types. Concentric hypertrophy is due to pressure overload, while eccentric hypertrophy is due to volume overload.
The risk of death in individuals with aortic insufficiency, dilated ventricle, normal ejection fraction who are asymptomatic is about 0.2 percent per year. Risk increases if the ejection fraction decreases or if the individual develops symptoms.
Individuals with chronic (severe) aortic regurgitation follow a course that once symptoms appear, surgical intervention is needed. AI is fatal in 10 to 20% of individuals who do not undergo surgery for this condition. Left ventricle dysfunction determines to an extent the outlook for severity of aortic regurgitation cases.
Aortic insufficiency or aortic regurgitation can be treated either medically or surgically, depending on the acuteness of presentation, the symptoms and signs associated with the disease process, and the degree of left ventricular dysfunction. Surgical treatment in asymptomatic patients has been recommended if the ejection fraction falls to 50% or below, in the face of progressive and severe left ventricular dilatation, or with symptoms or abnormal response to exercise testing. For both groups of patients, surgery before the development of worsening ejection fraction/LV dilatation is expected to reduce the risk of sudden death, and is associated with lower peri-operative mortality. Also, surgery is optimally performed immediately in acute cases.
Athlete's heart is not dangerous for athletes (though if a nonathlete has symptoms of bradycardia, cardiomegaly, and cardiac hypertrophy, another illness may be present). Athlete's heart is not the cause of sudden cardiac death during or shortly after a workout, which mainly occurs due to hypertrophic cardiomyopathy, a genetic disorder.
No treatment is required for people with athletic heart syndrome; it does not pose any physical threats to the athlete, and despite some theoretical concerns that the ventricular remodeling might conceivably predispose for serious arrhythmias, no evidence has been found of any increased risk of long-term events. Athletes should see a physician and receive a clearance to be sure their symptoms are due to athlete’s heart and not another heart disease, such as cardiomyopathy. If the athlete is uncomfortable with having athlete's heart or if a differential diagnosis is difficult, deconditioning from exercise for a period of three months allows the heart to return to its regular size. However, one long-term study of elite-trained athletes found that dilation of the left ventricle was only partially reversible after a long period of deconditioning. This deconditioning is often met with resistance to the accompanying lifestyle changes. The real risk attached to athlete's heart is if athletes or nonathletes simply assume they have the condition, instead of making sure they do not have a life-threatening heart illness.
Right ventricular hypertrophy (RVH) is a form of ventricular hypertrophy affecting the right ventricle.
Blood travels through the right ventricle to the lungs via the pulmonary arteries. If conditions occur which decrease pulmonary circulation, meaning blood does not flow well from the heart to the lungs, extra stress can be placed on the right ventricle. This can lead to right ventricular hypertrophy.
It can affect electrocardiography (ECG) findings. An ECG with right ventricular hypertrophy may or may not show a right axis deviation on the graph.
The ventricles are the chambers in the heart responsible for pumping blood either to the lungs (right ventricle) or to the rest of the body (left ventricle). Ventricular hypertrophy may be divided into two categories: concentric (maladaptive) hypertrophy and eccentric (adaptive) hypertrophy.
Concentric hypertrophy results from various stressors to the heart including hypertension, congenital heart defects (such as Tetralogy of Fallot), valvular defects (aortic coarction or stenosis), and primary defects of the myocardium which directly cause hypertrophy (hypertrophic cardiomyopathy). The underlying commonality in these disease states is an increase in pressures that the ventricles experience. For example, in tetralogy of Fallot, the right ventricle is exposed to the high pressures of the left heart due to a defect in the septum; as a result the right ventricle undergoes hypertrophy to compensate for these increased pressures. Similarly, in systemic hypertension, the left ventricle must work harder to overcome the higher pressures of the vascular system and responds by thickening to deal with increased wall stress.
Concentric hypertrophy is characterized by an addition of sarcomeres (the contractile units of cardiac cells) in parallel. The result is an increase in thickness of the myocardium without a corresponding increase in ventricular size. This is maladaptive largely because there is not a corresponding proliferation of the vasculature suppling the myocardium, resulting in ischemic areas of the heart. Ultimately, this response can be compensatory for a duration, and allow for improved cardiac function in the face of stressors. However, this type of hypertrophy can result in a dilated ventricle which is unable to effectively pump blood, leading to heart failure. When stressors that encourage this concentric hypertrophy are reduced or eliminated (either surgically corrected in the case of cardiac defects, or hypertension is reduced from diet and exercise) it is possible for the heart to undergo 'reverse remodeling' instead of progressing to a dilated phenotype.
Eccentric hypertrophy is generally regarded as healthy, or physiologic hypertrophy and is often termed "athlete's heart." It is the normal response to healthy exercise or pregnancy, which results in an increase in the heart's muscle mass and pumping ability. It is a response to 'volume-overload', either as a result of increased blood return to the heart during exercise, or a response to an actual increase in absolute blood volume as in pregnancy. This increase in pumping ability is the result of the addition of sarcomeres in series, which enables the heart to contract with greater force. This is explained by the Frank Starling mechanism, which describes the sarcomere's ability to contract with greater force as more of the elements of its contractile units become engaged. This response can be dramatic; in trained athletes have hearts that have left ventricular mass up to 60% greater than untrained subjects. Rowers, cyclists, and cross-country skiers tend to have the largest hearts, with an average left ventricular wall thickness of 1.3 centimeters, compared to 1.1 centimeters in average adults. Though eccentric hypertrophy is termed 'athlete's heart' it is typically only found in individuals who are aerobically conditioned. For example, weight lifters tend to undergo remodeling which more closely resembles concentric hypertrophy, as the heart does not experience a volume-overload, but instead responds to transient pressure overload as a consequence of increased vascular resistance from pressures exerted on arteries by sustained muscular contraction.
Though it is the case that eccentric hypertrophy is largely considered to be a healthy response to increased cardiac demand, it is also associated with risks. For example, in athlete's with significantly increased left ventricular weight there is also a corresponding increased risk for conduction abnormalities and sudden cardiac death. Additionally, in pregnant individuals, a subpopulation progress to peripartum cardiomyopathy, characterized by a dilation of the left ventricle and a corresponding deficit in heart function. There are suggestions that this progression is partially determined by underlying metabolic derangement (diabetes) and hypertension which may result in a more maladaptive cardiac response to pregnancy. As such, though it is convenient to consider clear cut distinctions between pathologic and physiologic cardiac hypertrophy, there may be a broader range of phenotypes than may be accounted for by gross cardiac phenotypes alone.
The development of pathologic states in LVH is complex. Electrical abnormalities are commonly found in individuals with LVH, both ventricular and super-ventricular tachycardia. Additionally, cytoarchitecture and the extracellular environment of the myocardium are altered, specifically genes typically expressed in the fetal heart are induced, as are collagen and other fibrotic proteins. LVH may interfere with heart functionality in a number of ways. Before progression to a dilated phenotype, mechanical obstruction of the outflow tract can occur, leading to reduced cardiac output. Additionally, increased fibrosis of the ventricle can result in a failure to relax appropriately which impairs cardiac filling and may lead to diastolic dysfunction or heart failure with preserved ejection fraction.
Concentric hypertrophy is a hypertrophic growth of a hollow organ without overall enlargement, in which the walls of the organ are thickened and its capacity or volume is diminished.
Sarcomeres are added in parallel, as for example occurs in hypertrophic cardiomyopathy.
In the heart, concentric hypertrophy is related to increased pressure overload of the heart, often due to hypertension and/or aortic stenosis. The consequence is a decrease in ventricular compliance and diastolic dysfunction, followed eventually by ventricular failure and systolic dysfunction.
Laplace's law for a sphere states wall stress (T) is proportionate to the product of the transmural pressure (P) and cavitary radius (r) and inversely proportionate to wall thickness (W): In response to the pressure overload left ventricular wall thickness markedly increases—while the cavitary radius remains relatively unchanged. These compensatory changes, termed "concentric hypertrophy," reduce the increase in wall tension observed in aortic stenosis.
Right atrial enlargement is a form of cardiomegaly. It can broadly be classified as either right atrial hypertrophy (RAH) or dilation. Common causes include right ventricular failure, pulmonary hypertension, tricuspid regurgitation, tricuspid stenosis and atrial septal defect.
It is characterized by a P wave height greater than 2.5 mm.
Left bundle branch block (LBBB) is a cardiac conduction abnormality seen on the electrocardiogram (ECG). In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract later than the right ventricle.
If untreated, severe symptomatic aortic stenosis carries a poor prognosis with a 2-year mortality rate of 50-60% and a 3-year survival rate of less than 30%. Prognosis after aortic valve replacement for people who are younger than 65 is about five years less than that of the general population; for people older than 65 it is about the same.
Common causes include:
- Pulmonary hypertension
- Tetralogy of Fallot
- Pulmonary valve stenosis
- Pulmonic regurgitation
- Ventricular septal defect (VSD)
- High altitude
- Cardiac fibrosis
- Chronic obstructive pulmonary disease (COPD)
- Athletic heart syndrome
Hyperdynamic precordium is a condition where the precordium (the area of the chest over the heart) moves too much (is "hyper dynamic") due to some pathology of the heart. This problem can be hypertrophy of the ventricles, tachycardia, or some other heart problem.
Hyperdynamic precordium can also be due to hyperthyroidism, and thus indicates an increased cardiac contractility, with systolic hypertension. It may also be due to aortic coarctation, and most other congenital heart malformations.
Palpation of the chest wall can be done to assess volume changes within the heart. A hyperdynamic precordium reflects a large volume change.
Among the causes of LBBB are:
- Aortic stenosis
- Dilated cardiomyopathy
- Acute myocardial infarction
- Extensive coronary artery disease
- Primary disease of the cardiac electrical conduction system
- Long standing hypertension leading to aortic root dilatation and subsequent aortic regurgitation
- Lyme disease
- Side effect of some cardiac surgeries (e.g., aortic root reconstruction)
Although not based on a human clinical trial, the only currently accepted disease-modifying therapeutic strategy available for familial amyloid cardiomyopathy is a combined liver and heart transplant. Treatments aimed at symptom relief are available, and include diuretics, pacemakers, and arrhythmia management. Thus, Senile systemic amyloidosis and familial amyloid polyneuropathy are often treatable diseases that are misdiagnosed.
In 2013, the European Medicines Agency approved the drug tafamidis (Vyndaqel) to slow the progression of familial amyloid polyneuropathy, a related disease caused by TTR aggregation that first presents as an autonomic and/or peripheral neuropathy (later progressing to a cardiomyopathy).
People on bisphosphonates have less progression of aortic stenosis and some regressed. This finding led to multiple trials which are ongoing. Subsequent research has failed to confirm the initial positive result.