Pulmonary arterial Hypertension

Identified for the first time in 1891 by Doctor Ernst Von Romberg, the pulmonary arterial hypertension corresponds to a group of diseases of progressive evolution characterized by an abnormal rise in the blood Pression on the level of the pulmonary arteries, whose principal symptom is a breathlessness of effort.
Selon the cause, pulmonary arterial hypertension can be a severe disease with a tolerance with the effort very definitely decreased and a right cardiac failure.

In the majority of the cases, no cause is found. One then speaks about pulmonary arterial hypertension Idiopathique (in its sporadic form ) or family. She is sometimes associated with various diseases (auto-immune Maladie, Infection S,…) or with the use of Drug S (Amphetamine S growth regulators…).
Il exists also various pathologies which being accompanied by a pulmonary arterial hypertension, the such thrombo-embolic Maladie for example.

Pulmonary arterial hypertension was initially classified in two categories: the primitive form and the secondary form. A new classification, more exhaustive, was proposed.

The low specificity of the Symptôme S often involves a delay with the diagnosis.

The treatment is medical and of modest effectiveness.

Epidemiology

The Prévalence is estimated at 15 case for a million inhabitants (adult) and the incidence of 2,4 cases per million inhabitants (adult) per annum.
Elle touches 1,7 women for 1 man. The peak of frequency ranges between 30 and 40 years.

Physiopathology

Physiopathological mechanisms

Pulmonary arterial hypertension is defined by a rise in the average pulmonary blood (PAP) pressure, which becomes higher than 20 mm of mercury at rest or 30 mm of mercury to the effort; whereas at the healthy subject, it is included/understood between 10 and 15 mm of mercury. It should be noted that there exists an increase in the PAP during ageing, but this increase is discrete (about 1 mm of mercury by 10 year old sections).

The pulmonary blood pressure is dependant on the capillary pressure pulmonary, the pulmonary blood flow and pulmonary vascular resistances according to the following formula:

$PAP=PCP+ (\ dowry Q. RVP)$

with:

PAP : Average pulmonary blood pressure,
PCP : Pulmonary capillary pressure,
$\ dowry Q$ : Pulmonary blood flow,
RVP : pulmonary vascular resistance.

The pulmonary blood pressure thus will be increased in the event of increase:

of the pulmonary capillary pressure, secondary with an increase in pressure Veine uses pulmonary, itself secondary with a left cardiac failure (ischemic) or with a mitral Rétrécissement. One speaks then about hypertension post-capillary.
of the pulmonary blood flow, in some congenital cardiopathies (inter-auricular Communication or inter-ventricular, Persistence of the arterial channel).
of pulmonary vascular resistances, mainly in the chronic lung diseases. One speaks about hypertension pre-capillary.

The principal physiopathological mechanisms are a Vasoconstriction, a vascular replanning and phenomena of Thrombose which gradually will involve an increase in pulmonary vascular resistances.
La vasoconstriction is component early of pulmonary arterial hypertension. It can be the expression of an abnormal operation of the potassic channels or with a dysfunction of the vascular endothelium (inducing the chronic production of Vasodilatateur S). Vascular replanning implies all the layers of the vascular wall and is characterized by modifications of fabrics (see Chapitre " Histopathologie ").

The rise in the blood pressure has mainly a repercussion on the ventricle right. When it is healthy, this structure has a thin wall which dilates easily. But the influence of hypertension leads to a hypertrophy ventricular right-hand side, then with a ventricular insufficiency responsible for Dyspnée of effort (breathlessness to the effort), of oedemas of lower extremities, increase in the volume of the Foie had with its congestion (Hépatomégalie). In the long run, that can involve a irreversible Cardiac failure, and even occurred of a brutal cardiac arrest at the time of an effort.

Histopathologie

Cellular anomalies were described in the pulmonary vascularization of the subjects reached and could play a part in the development and the progression of the disease. These anomalies include dysfunction of the pulmonary Endothélium with an abnormal synthesis substances vasodilatatrices (Oxyde nitric (NO), of Thromboxane A2, Prostacycline and Endothéline (endothéline-1, ET-1)), a deterioration of the potassic channels.
De more, of the lesions is located in all the various structures of the wall of the blood-vessels and includes a hypertrophy Média (secondary at the same time with a hypertrophy and a hyperplasy of the smooth muscle fibers and an increase in the conjunctive Tissu), a thickening of the Intima and Adventice (by increased production of extracellular Matrice) associated with more complex lesions.

Causes

The causes most often listed pulmonary arterial hypertension include the infection by HIV, the Sclérodermie and others autoimmune diseases, the Cirrhose and the Hypertension portale, the Drépanocytose, the thyroid pathologies, some congenital cardiopathies, the Sarcoïdose, the Histiocytose X. It can also be secondary with the chronic obstruction of the pulmonary vessels by clots (embolic HTAPS post- ).
Certains behaviors also pouvent to start this variation of blood Pressure such as the catch of drugs growth regulators, of Cocaïne, Méthamphétamine, alcohol.
Les pulmonary pathologies responsales of Hypoxie is also causes of pulmonary hypertension: the obstructive chronic Broncho-pneumonopathy, the Syndrome of Pickwick.
It should be noted that there exist family forms, related to a change on gene BMPR2 ( standard Bone morphogenetic protein receptor II ). The Pénétrance of this change is incomplete, about 15 to 20%.

When no cause can be identified, one speaks about primitive or idiopathic pulmonary hypertension arterial.

There exists a etiologic classification of established by WHO in 1998 and revised in 2003 when pulmonary arterial hypertension is separate in five categories, themselves divided into subcategories:

pulmonary arterial Hypertension:

idiopathic form (no found cause and absence of family antecedents),
family form,
associated with a Connectivity, with a congenital Cardiopathie, a Hypertension portale, an infection by HIV, with the use of Drug S and Toxin S, others (thyroid disorders , Disease of Left-handed person, Hémoglobinopathie S, syndromes myéloprolifératifs),
associated with a pathology Veine uses or capillary (pulmonary veino-occlusive disease, pulmonary Hémangiome capillary),
persistent pulmonary hypertension of New-born,

pulmonary venous Hypertension associated with diseases of the left Heart:

diseases of the auricle or the left ventricle,
valvular diseases of the left heart,

pulmonary Hypertension associated with a lung disease and/or a Hypoxémie (obstructive chronic broncho-pneumonopathies, syndrome of apnea of the sleep, interstitial diseases pulmonary, chronic exposure to high-altitudes),
pulmonary hypertension due to a thrombo-embolic Disease (by thrombo-embolic obstruction of the pulmonary proximales or distal arteries, or by an obstruction of nonthrombotic origin (Tumor, parasite, foreign body)),
Various: Sarcoidosis, Histiocytose X, Lymphangiomatose, compression of the pulmonary vessels (Adenopathy S, tumor, Médiastinite fibrosante).

Diagnosis

The signs of this pathology not being specific, there exists often a delay diagnosis. This delay is estimated 18 months at 2 years on average.

Functional signs

There do not exist functional signs sepcific.
Le prone can feel a Dyspnée effort (which is the cardinal sign of this pathology), of the thoracic pains (of angineuse pace , retro sternales, constrictive of effort and/or rest), a nonproductive Toux, Lipothymie S (even real Syncope S of effort), a Asthénie (great tiredness), Palpitation S, more rarely of the Hémoptysie S of low abundance (presence of Sang at the time of efforts of cough), a Dysphonie.
Il usually has there neither Orthopnée (breathing difficulty in position lying), nor night Dyspnée paroxystic.

Clinical signs

There do not exist clinical signs specific to this pathology.
L' cardiac Auscultation can highlight a Tachycardie (even a arrhythmia), a glare of B2 (second cardiac noise) on the level of the pulmonary hearth (quasi-constant sign), a systolic breath of functional Insuffisance tricuspide, a diastolic breath of pulmonary insufficiency.
L' pulmonary sounding is usually normal.
L' clinical examination must seek signs of right ventricular insufficiency.

Complementary examinations

Biology

Standard biology is classically normal. The anomalies which can however be found are not specific: Thrombopénie and moderated Anemia, Impaired renal function, anomalies of the hepatic assessment, spontaneous Rate of prothrombine low.
Une search for Anticorps will be carried out in order to seek a auto-immune Maladie.

The rate of Endothéline is high in the plasma and pulmonary fabric of the patients having a pulmonary arterial hypertension. This rate seems proportional to severity and the forecast of the disease.

Electrocardiogram

The electrocardiogram can show signs of hypertrophy of the ventricle right and right auricle. The rate/rhythm is usually sinusal (normal), although turbid of the rate/rhythm are possible. A normal ECG does not eliminate the diagnosis.

Radiograph standard

The pulmonary Radiologie is abnormal in the majority of the cases (90%). It then will show an increase in the cardiac silhouette (cardiomégalie) and an increase in the volume of the pulmonary diameter arterial trunk and pulmonary arteries proximales.

cardiac Catheterization right

It is an invasive exploration of the pulmonary Artère aiming at establishing with certainty the existence of a pulmonary arterial hypertension. It is also useful for the evolutionary follow-up of the disease. This examination consists in putting a catheter (small flexible tube, generally out of plastic) in a pulmonary artery to measure the pressures on this level.

cardiac Echography

Cardiac echography makes it possible to make the diagnosis, to evaluate the gravity and the repercussion of pulmonary arterial hypertension and to seek an etiology.
Elle will allow the estimate of the systolic pressure in the pulmonary artery ( PASP ). This pulmonary systolic blood pressure is equivalent to the systolic pressure of the ventricle right. PASP is estimated by measuring the throughput speed of blood flow through the cardiac Valve tricuspide (V) and an estimated pressure of the right auricle (RAP). The PASP is thus estimated using the following formula: $PASP=4V^2+RAP$ .

Using the Doppler, it could be calculated a gradient (difference) of pressure with through some cardiac valves (tricuspide or pulmonary).

Other examinations

Other examinations could be realized: a thoracic Scanner in particular to evaluate a possible thrombo-embolic disease, and also to seek it of a pathology of the pulmonary Parenchyma, a pulmonary Scintiscanning of perfusion (even of ventilation/perfusion), respiratory functional explorations to evaluate the respiratory capacity.
La realization of a pulmonary Biopsie does not have established interest.

Evaluation of severity

The severity of arterial hypertension is with dimensions according to functional classification OMS/NYHA:

Class I: absence of limitation of the physical-activity. The usual physical-activities do not cause disorders.
Class II: light limitation of the physical-activity. Asymptomatic at rest. The usual physical-activities cause a Dyspnée or a tiredness or thoracic pains or Lipothymie S.
Classe III: marked limitation of the physical-activity. Asymptomatic at rest. An effort less intense than the activity of the daily life induces a dyspnea or a tiredness.
Class IV: incapacity with the least effort. Demonstrations of right Cardiac failure. Dyspnea or tiredness can be present at rest. The embarrassment is increased with the least effort.

Assumption of responsibility

The basic salary associates, according to the cases, a treatment Anticoagulant, a oxygen treatment, Digitalique S, the Diurétique S, the calcic inhibiting (Nifédipine, Diltiazem).
Les other treatments being able to be proposed in addition to the basic salary are:

the époprosténol (Prostacyclin), into intravenous continuous,
the Bosentan, inhibiting competitive of the receiving S of the Endothéline, treatment by oral way,
the Sildénafil, inhibiter of the Phosphodiestérase,
the Iloprost, Similar of prostacyclin, Vasodilator and plate Antiagrégant, by inhaled way.

As a last resort, he will be possibly proposed a pulmonary transplantation or a transplantation of the block artificial heart-lung.

Evolution and complications

The natural evolution of this disease is very variable from one individual to another. It leads more or less quickly to the right ventricular insufficiency. The death can occur in a few months or after several years.

The Médiane of survival is from two to three years after the diagnosis, there is 75% of mortality at five years.

The complications are thrombo-embolic risks, pushes of cardiac failure (acute edema of the lung), a risk of Sudden death.
Une Grossesse is extremely dangerous during a HTAP, with important a Morbidité and mortality fœto-nursery schools

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