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Pulmonary hypertension in congenital heart disease

Pulmonary hypertension was defined as an average pulmonary artery pressure by more than 25 mmHg at rest, measurements made ​​by the right heart catheterization.

Pulmonary hypertension in congenital heart diseaseRecent measurements have revised the limit values ​​so that, at present, the pressure of the normal lung is 14 + / – 3 mm Hg, with an upper limit of normal of 20 mm Hg. The significance of values ​​from 21 to 24 mm Hg remains unclear to present, patients presenting with pulmonary pressures in this range require reviews in further epidemiological studies. The definition of pulmonary hypertension at effort as higher than 30 mmHg value measured by right heart catheterization is not determined by international consensus; normal people can reach much higher values ​​even during exercise without frame is pathological.

Pulmonary hypertension (PH) may be idiopathic, inherited, induced by medication, drugs, toxins, associated with various diseases – connective tissue disease, HIV, portal hypertension, congenital diseases, schistosomiasis, chronic hemolytic anemia – may be included separately for example, within the entity persistent pulmonary hypertension in the newborn. PH can be caused by left or right heart pathology – through diastolic or systolic dysfunction or heart valvular pathology. Also PH may be caused by lung diseases and / or hypoxia, describing it in the etiology: chronic obstructive pulmonary disease, interstitial lung disease, restrictive or obstructive pulmonary disease, sleep pathology, pulmonary alveolar hypoventilation, chronic exposure to high altitude, abnormal lung development. Pulmonary thromboembolism is involved in the development of PH. There are, of course, unclear multifactorial mechanisms and factors such as haematological diseases – myeloproliferative disorders, splenectomy, systemic diseases – sarcoidosis, Langerhans histiocytosis, neurofibromatosis, vasculitis, metabolic diseases – Gaucher disease, thyroid pathology and many others types of chronic renal failure, dialysis, fibrosing mediastinitis.

Clinical classification of the congenital shunts associated with PH involves four entities: Eisenmenger syndrome, systemic-to-pulmonary shunts, pulmonary hypertension through minor defects and corrective cardiac PH pressure after surgery. Eisenmenger syndrome includes all systemic-pulmonary shunts caused by large defects leading to severe increase of venous pressure and lead to a reversible pulmonary-systemic or to a bidirectional shunt. Cyanosis, erythrocytosis and other malformations are consecutive. The second category includes patients with moderate to large shunts, to which increased pulmonary venous pressure is mild to moderate, systemic-pulmonary shunt is still present and cyanosis is not present at rest. In the third category, including minor defects, generally under 1cm ventricular septal defect and inter-atrial septal defects less than 2 cm, overlapping with the clinical picture is present in idiopathic pulmonary arterial hypertension. The fourth category includes patients with congenital heart disease was corrected, but the PH pressure is still present to precocious postoperative severe or reoccurs in a few months or in a few years after surgical correction, without the patient to be of any cardiac lesion significant residual.

Anatomopathological classification of congenital systemic-to-pulmonary shunts associated to PH involves the presence of multiple criteria. Depending on the type, there are simple pre-tricuspid shunts – for example, atrial septal defect, ostium secundum, ostium primum and sinus venous or anomalous pulmonary venous return all or part; simple post-tricuspid shunts – for example, patent arterial ducts or ventricular septal defect, congenital shunts combined and complex – atrioventricular septal defect, arterial trunk, single ventricle, transposition of great arteries. In terms of size, classification implies if we refer to a size criterion anatomically small to moderate defects – for example, atrial septal defect under 2 cm and less than 1 cm ventricular septal defect, and large defects, for example, defect atrial septal than 2 cm, respectively, above 1 cm ventricular cardiac deficiency of the substance. When referring to the flow rate as a criterion involving size, depending on the ratio of flow rates, the disease can be restrictive or unrestrictive, calculated for differentiating lung versus systemic flow ratio. The shunt direction is also a criterion of classification, shunts can be: predominantly systemic to pulmonary to systemic or bidirectional lung.

From the point of view of the repairer status, shunts may be not operated yet, repaired or palliative surgery performed.

Pathological diagnosis of this entity requires the use of a series of investigations to clarify, in addition to proper diagnosis and etiology, assessment of functional and hemodynamic dysfunction.

The clinical presentation involves the presence of nonspecific symptoms, which include shortness and difficulty in breathing, weakness, angina, syncope, abdominal distension.

Symptoms present at rest are only in very advanced cases.

Physical signs involves emphasizing the pulmonary  component of the second noise, para-systolic murmur of pulmonary regurgitation, diastolic murmur of pulmonary insufficiency, the third right noise, jugular distension, hepatomegaly, peripheral edema, ascites, cold extremities, signs present in the patient with advanced pulmonary hypertension. Pulmonary sounds are normal clinical examination. Telangiectasia, digital ulceration, sclerodactyly are present in scleroderma, the clicking inspiratory reveals the interstitial lung disease etiology.

Electrocardiogram suggests signs of right ventricular hypertrophy, right atrial enlargement, right ventricular hypertrophy is present in over 87% of cases, right axis deviation is present in over 79% of cases. The absence of obvious signs does not exclude the presence of pulmonary hypertension. The sensitivity of the electrical signs is 50% and their specificity is 70% in the detection of pulmonary hypertension.

Pulmonary Radiography is abnormal in 90% of patients with pulmonary arterial dilatation involving the central, peripheral vascular loss, right atrial dilatation and right ventricular.

Pulmonary function tests, arterial blood gases are very useful.

Echocardiography provides values ​​of pulmonary artery pressure.

You can also perform the diagnostic tests: pulmonary ventilation perfusion scintigraphy, tomography and pulmonary angiography, cardiac MRI, blood tests and immunological complex, right heart catheterization.

Therapy involves numerous hygienic dietary steps, lifestyle, and drugs. Oral anticoagulants, diuretics, oxygen, digoxin, calcium channel blockers, prostanoids – prostacyclin, epoprostenol, iloprost, treprostinil, endothelin receptor antagonists, bosentan, sitaxsentan, phosphodiesterase inhibitors sildenafil, tadalafil are part of medicinal actions, subject to complex and rigorous protocols.

We mention among the interventional measures, balloon atrial septostomy, pulmonary or cardiopulmonary transplantation belonging to appropriate surgical measures of this pathological entity.

Regarding to the particular case of Eisenmenger syndrome, signs and symptoms resulting from low oxygen saturation in arterial blood and secondary erythrocytosis, including dyspnea, fatigue, and syncope. In patients without inverted shunts, the degree of cyanosis and erythrocytosis may be mild to moderate.

Patients also suffer from hemoptysis, brain injuries, brain abscesses, coagulation abnormalities, sudden death. They have a low life expectation; can survive until the third or fourth decade of life.

Improving the survival may be the result of preservation of right ventricular function if it is not remodeled at birth and remains hypertrophied.

Treatment of patients with Eisenmenger syndrome should be applied in specialized centers, patient education, behavioral measures, modeling risk factors constitute a major part in the management of the quality of life of these patients. They can present a clinical deterioration in different circumstances, which include non-cardiac surgery with general anesthesia, dehydration, lung infection, life at high altitude.

These patients are advised to avoid stressful physical efforts, gentle physical activities making it extremely beneficial.

Pregnancy is associated with a major risk to mother and fetus, desirable as they discourage and encourage contraception.

Long-term oxygen therapy may improve symptoms but do not alter the survival of, at least on the night of therapy only, are not conclusive data in case of circadian therapy.

Use of oral contraceptives in Eisenmenger syndrome is controversial, incidence of pulmonary arterial thrombosis and stroke was reported, while there is an increased risk of hemorrhage and hemoptysis.

Oral anticoagulant therapy is recommended for those patients with pulmonary arterial thrombosis Eisenmenger showing signs of heart failure and the absence or minor hemoptysis. The presence of signs of hyperviscosity makes beneficial practice of phlebotomy to replace fluids, especially when the hematocrit is above 65%. General medical therapies listed above have rigorous protocols of ordering and grouping.

Heart lung transplantation or the lung only with adjacent cardiac surgery is an option for cases nonresponsive to medical therapy, but was limited by the low availability of viable organs.

For PH associated with congenital cardiac shunts, the order of medical preference based on the class indications such as: bosentan class I indication, phosphodiesterase inhibitors indication class II, class IIa anticoagulant therapy, oxygen supplementation class IIa, phlebotomy with isovolemic replacement class IIa and, last, class IIb indication, combination therapies especially Eisenmenger syndrome.

In general, surgical treatment of congenital heart left/ right cardiac shunt is an intervention that must be practiced before installing irreversible lesions. Hemodynamics orders and classifies several subgroups of patients: one in which increasing pulmonary blood flow and decreased pulmonary vascular resistance permit a curative surgical gesture, the second group, slightly increases the pulmonary vascular resistance increases the risk of surgical repair, and the group of third, the advanced pulmonary vascular disease and specific physiological Eisenmenger syndrome surgery are prohibited. Clinical and therapeutic modalities differ according to these various groups. The heart lung transplantation or only pulmonary with repair associated with heart failure represents the ultimately last resort in patients with vascular lung disease associated. In patients with PH secondary to congenital heart artery shunt left and right requires a surgical repair very precocious in life to prevent the occurrence and progression of pulmonary vascular lesions and to allow complete healing. For patients with a hemodynamic which contraindicates a reconstructive surgery and associated to with pulmonary vascular lesions (Eisenmenger), new therapies are promising, but it is absolutely necessary to conduct rigorous randomized trials to confirm the results of the studies so far uncontrollable. Current clinical development makes it extremely likely the possibility in the near future, the emergence of entirely different therapies presently practiced with much higher rate of survival and, why not, healing.

To remember

Congenital heart defects are among the most common diseases and most commonly associated with right-left shunt. They are characterized by increased pulmonary blood flow and, at times, with the development of pulmonary arterial hypertension. In the French case-law of the past 10 years, for example, 13% of cases had pulmonary hypertension as causes of congenital heart disease. Increased pulmonary flow causes anatomical and functional changes in the pulmonary vascular bed. A change in pulmonary vascular tone explains the complex interactions between endothelial vasoactive substances. Histological changes in pulmonary hypertension secondary to congenital heart disease are similar to those of idiopathic pulmonary hypertension. Endothelial mediators involved are endothelin I, thromboxane A2 – vasoconstrictor and activator of tissue proliferation, prostacyclin and nitric oxide – vasodilator and anti-proliferative tissue. Remodeling of the pulmonary vascular bed is reversible in early stages, but later changes become final. The surgically repaired gesture is made precociously in life.

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