Eisenmenger syndrome | |
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Other names | ES, Eisenmenger's reaction, Eisenmenger physiology, or Tardive cyanosis |
Schematic drawing showing the principles of Eisenmenger's syndrome | |
Specialty | Medical genetics |
Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect (typically by a ventricular septal defect, atrial septal defect, or less commonly, patent ductus arteriosus) causes pulmonary hypertension [1] [2] and eventual reversal of the shunt into a cyanotic right-to-left shunt. Because of the advent of fetal screening with echocardiography early in life, the incidence of heart defects progressing to Eisenmenger syndrome has decreased.
Eisenmenger syndrome in a pregnant mother can cause serious complications, [3] though successful delivery has been reported. [4] Maternal mortality ranges from 30% to 60%, and may be attributed to fainting spells, blood clots forming in the veins and traveling to distant sites, hypovolemia, coughing up blood or preeclampsia. Most deaths occur either during or within the first weeks after delivery. [5] Pregnant women with Eisenmenger syndrome should be hospitalized after the 20th week of pregnancy, or earlier if clinical deterioration occurs.
Signs and symptoms of Eisenmenger syndrome include the following: [6]
One of the most severe and common complications of Eisenmenger syndrome is cardiac arrhythmia, especially supraventricular arrhythmias. Approximately 40% of patients diagnosed with Eisenmenger syndrome were also found to have these arrhythmias during routine ECG screenings. These arrhythmias have worse prognosis in patients with Eisenmenger syndrome, compared to the general population, and can be a source of sudden cardiac death. [8]
A number of congenital heart defects can cause Eisenmenger syndrome, including atrial septal defects, ventricular septal defects, patent ductus arteriosus, and more complex types of acyanotic heart disease. [1]
The reason Eisenmenger syndrome often presents later in life can be explained by alterations of the normal physiology of the heart and the maladaptive responses that occur over time. The larger and more muscular left side of the heart must generate the high pressure required to supply blood to the extensive, high-resistance systemic circulation. In contrast, the smaller, right side of the heart must generate a much lower pressure in order to pass blood through the low-resistance, high compliance circulation of the lungs. The lungs are able to accomplish this low-resistance circulation largely due to the fact that the length of the pulmonary circulation is smaller, and because much of the circuitry is in parallel rather than in series. [ citation needed ]
If a significant anatomic defect (i.e. a hole or breach) exists between the two sides of the heart, a shunt will occur, causing blood to flow down the normal pressure gradient from the left side to the right side. The amount of blood shunted is proportional to the size of the defect, and the beat-to-beat volume of blood pumped through a left-to-right breach is a percentage of anticipated cardiac output (CO) of the left ventricle. Clinically a low index or percentage of CO ejected through a shunt is harmless; a high index or percentage of CO ejected through a left-to-right shunt heralds Eisenmenger's physiology.[ citation needed ]
The left-to-right shunting of blood results in abnormally high blood flow and pressure directed to the right heart circulation, gradually leading to maladaptive changes that ultimately result in pulmonary hypertension. Increased right-sided blood volume and pressure causes a cascade of pathologic damage to the delicate pulmonary capillaries, causing them to be incrementally replaced with scar tissue. Scar (dead lung tissue) does not contribute to oxygen transfer, therefore decreasing the useful volume of the pulmonary vasculature. The scar tissue also provides less flexibility and compliance than normal lung tissue, causing further increases in pulmonary blood pressure, and the weakened heart must pump harder to continue supplying the lungs, leading to damage of more capillaries. It is because of this maladaptive response that at the onset of Eisenmenger syndrome, the damage is considered irreversible, even if the underlying heart defect is corrected after the fact.[ citation needed ]
Eventually, due to increased resistance and decreased compliance of the pulmonary vessels, elevated pulmonary pressures cause the myocardium of the right heart to hypertrophy (RVH). The onset of Eisenmenger syndrome begins when right ventricular hypertrophy causes right heart pressures to exceed that of the left heart, leading to reversal of blood flow through the shunt (i.e., blood moves from the right side of the heart to the left side). As a consequence, deoxygenated blood returning from the body bypasses the lungs through the reversed shunt and proceeds directly to systemic circulation, leading to cyanosis and resultant organ damage.[ citation needed ]
The defect, now a right-to-left shunt, causes reduced oxygen saturation in the arterial blood due to mixing of oxygenated blood returning from the lungs with the deoxygenated blood returning from systemic circulation. This decreased saturation is sensed by the kidneys, resulting in a compensatory increase in erythropoietin production and an increased production of red blood cells in an attempt to increase oxygen delivery. As the bone marrow increases erythropoiesis, the systemic reticulocyte count and the risk for hyperviscosity syndrome increases. Reticulocytes are less efficient at carrying oxygen as mature red cells, and they are less deformable, causing impaired transit through capillary beds. This contributes to the death of pulmonary capillary beds.[ citation needed ]
A person with Eisenmenger syndrome is paradoxically subject to the possibility of both uncontrolled bleeding due to damaged capillaries and high pressure, as well as spontaneous clots due to hyperviscosity and stasis of blood.[ citation needed ]
Diagnosis of Eisenmenger syndrome is typically conducted via transthoracic echocardiography, which facilitates the identification and evaluation of shunts, anatomical defects, and ventricular function. Following diagnosis, or in some cases of inconclusive diagnosis, a cardiac catheter may be used to both confirm the diagnosis and to assess the patient's pulmonary arterial pressure, an important predictive value for prognosis and treatment. [8]
If the inciting defect in the heart is identified before it causes significant pulmonary hypertension, it can normally be repaired through surgery, preventing the disease. [9] After pulmonary hypertension is sufficient to reverse the blood flow through the defect, however, the maladaptation is considered irreversible, and a heart–lung transplant or a lung transplant with repair of the heart is the only curative option. Transplantation is the final therapeutic option and only for patients with poor prognosis and quality of life. Timing and appropriateness of transplantation remain difficult decisions. [5] 5-year and 10-year survival ranges between 70% and 80%, 50% and 70%, 30% and 50%, respectively. [10] [11] [12] Since the average life expectancy of patients after lung transplantation is as low as 30% at 5 years, patients with reasonable functional status related to Eisenmenger syndrome have improved survival with conservative medical care compared with transplantation. [13]
Various medicines and therapies for pulmonary hypertension are under investigation for treatment of the symptoms. [14] Air filters for intravenous lines are recommended for persons with Eisenmenger syndrome who have been hospitalized to reduce the risk of accidental introduction of air into the veins due to the increased risk for paradoxical air embolism. If air is introduced into the veins and travels through the ventricular septal defect into the arterial circulation, a stroke may occur.[ citation needed ]
Antiarrhythmic drugs are important for many patients with Eisenmenger syndrome, as evidence suggests that arrhythmia-induced sudden cardiac death may be the leading cause of death among patients with the disease. These therapies generally aim to restore and maintain sinus rhythm, but the specific interventions chosen will depend on the nature of the patient's arrhythmia. [8]
Eisenmenger syndrome was named [15] by Paul Wood after Victor Eisenmenger, who first described [16] the condition in 1897. [17]
Cardiology is the study of the heart. Cardiology is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists, a specialty of internal medicine. Pediatric cardiologists are pediatricians who specialize in cardiology. Physicians who specialize in cardiac surgery are called cardiothoracic surgeons or cardiac surgeons, a specialty of general surgery.
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Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, is a congenital heart defect characterized by four specific cardiac defects. Classically, the four defects are:
Pulmonary heart disease, also known as cor pulmonale, is the enlargement and failure of the right ventricle of the heart as a response to increased vascular resistance or high blood pressure in the lungs.
Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due to either failure of the left ventricle of the heart to remove oxygenated blood adequately from the pulmonary circulation, or an injury to the lung tissue directly or blood vessels of the lung.
Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the foramen ovale; however, when this does not naturally close after birth it is referred to as a patent (open) foramen ovale (PFO). It is common in patients with a congenital atrial septal aneurysm (ASA).
Pulmonary hypertension is a condition of increased blood pressure in the arteries of the lungs. Symptoms include shortness of breath, fainting, tiredness, chest pain, swelling of the legs, and a fast heartbeat. The condition may make it difficult to exercise. Onset is typically gradual.
A cyanotic heart defect is any congenital heart defect (CHD) that occurs due to deoxygenated blood bypassing the lungs and entering the systemic circulation, or a mixture of oxygenated and unoxygenated blood entering the systemic circulation. It is caused by structural defects of the heart such as right-to-left or bidirectional shunting, malposition of the great arteries, or any condition which increases pulmonary vascular resistance. The result may be the development of collateral circulation.
A ventricular septal defect (VSD) is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart. The extent of the opening may vary from pin size to complete absence of the ventricular septum, creating one common ventricle. The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.
The Fontan procedure or Fontan–Kreutzer procedure is a palliative surgical procedure used in children with univentricular hearts. It involves diverting the venous blood from the inferior vena cava (IVC) and superior vena cava (SVC) to the pulmonary arteries without passing through the morphologic right ventricle; i.e., the systemic and pulmonary circulations are placed in series with the functional single ventricle. The procedure was initially performed in 1968 by Francis Fontan and Eugene Baudet from Bordeaux, France, published in 1971, simultaneously described in 1971 by Guillermo Kreutzer from Buenos Aires, Argentina, and finally published in 1973.
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.
Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped and incapable of supporting the systemic circulation. It is estimated to account for 2-3% of all congenital heart disease. Early signs and symptoms include poor feeding, cyanosis, and diminished pulse in the extremities. The etiology is believed to be multifactorial resulting from a combination of genetic mutations and defects resulting in altered blood flow in the heart.
Atrioventricular septal defect (AVSD) or atrioventricular canal defect (AVCD), also known as "common atrioventricular canal" (CAVC) or "endocardial cushion defect" (ECD), is characterized by a deficiency of the atrioventricular septum of the heart that creates connections between all four of its chambers. It is caused by an abnormal or inadequate fusion of the superior and inferior endocardial cushions with the mid portion of the atrial septum and the muscular portion of the ventricular septum.
Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the body.
A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.
Right ventricular hypertrophy (RVH) is a condition defined by an abnormal enlargement of the cardiac muscle surrounding the right ventricle. The right ventricle is one of the four chambers of the heart. It is located towards the lower-end of the heart and it receives blood from the right atrium and pumps blood into the lungs.
A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. The direction may be controlled by left and/or right heart pressure, a biological or artificial heart valve or both. The presence of a shunt may also affect left and/or right heart pressure either beneficially or detrimentally.
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Raghib syndrome is rare a congenital heart defect where the left superior vena cava (LSVC) is draining into the left atrium in addition to an absent coronary sinus and an atrial septal defect. This can be considered a dangerous heart condition because it puts the individual at a high risk of stroke. Other defects that are often associated with Raghib syndrome can include ventricular septal defects, enlargement of the tricuspid annulus, and pulmonary stenosis. While this is considered an extremely rare developmental complex, cases regarding a persistent left superior vena cava (PLSVC) are relatively common among congenital heart defects. It is also important to note that the PLSVC often drains into the right atrium, and only drains into the left atrium in approximately 10 to 20% of individuals with the defect.
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