OVERVIEW
Plateau heart disease is basically characterized by chronic low-pressure hypoxia-induced pulmonary hypertension with right ventricular hypertrophy or right heart insufficiency. It can be divided into pediatric and adult plateau heart disease. This disease is easy to occur in the plateau above 3500m, mostly chronic, individual first into the plateau, especially children can be acute or subacute onset. Acute or subacute cases are characterized by right ventricular enlargement and congestive right heart failure caused by significant pulmonary hypertension, while chronic cases are characterized by right ventricular hypertrophy caused by right ventricular afterload and multiple organ damage.
Etiology
Hypoxia is the causative factor of this disease, and hypoxic pulmonary hypertension is the main manifestation of this disease. Highland hypoxia causes erythrocytosis, increased blood viscosity, increased total and pulmonary blood volume, and direct damage to the myocardium from hypoxia. Cold exposure, smoking, overwork, and upper respiratory tract infections are predisposing factors for this disease.
Symptoms
Pediatric onset at an early age, rapid progression of the disease, most of the manifestations of right heart failure, the beginning of the night cries sleeplessness, restlessness, loss of appetite, diarrhea, cough, etc., followed by mental depression, pale face, dyspnea, often breath holding, cyanosis, digestive tract dysfunction, may be episodes of fainting, and ultimately appear right heart failure, hepatomegaly, urinary oliguria, edema, etc.. Adults have a slow onset of disease, often occurring in the process of first entering the plateau or arriving at the plateau within a short period of time after the onset of the disease, especially in the sudden from the plains to the plateau, often due to respiratory infections or physical activity induced by palpitations, shortness of breath, cough, dyspnea, edema, etc., the symptoms of the left heart failure is more pronounced, the serious cases because of the acute left heart failure can be sudden death. Signs: the heart can be enlarged to one side or both sides, the anterior region of the heart heard 1/6 ~ 3/6 systolic wind-like murmur, the second tone of the pulmonary valve area hyperpnea, can be accompanied by splitting, blood pressure is lowered, both lungs can have scattered wet rales, liver enlargement. Chronic plateau heart disease is mostly seen in adults who have moved to the plateau for many years, often combined with erythrocytosis and (or) plateau hypertension. The main clinical manifestations are divided into two stages:
1. Cardiac function compensation period
Patients can tolerate for a long time without any conscious signs and symptoms, and heart failure occurs only under the effect of certain triggers, such as excessive fatigue, infection, mental stress, or transferring to a higher altitude area from the plateau, or returning to the plateau from the plains, etc. Most of the patients have mild enlargement of the heart. Most of the patients have mild heart enlargement, the apical part of the heart heard 2/6 systolic wind-like murmur, the second tone of the pulmonary valve area hypertonic, the lungs a little wet rales, usually no obvious symptoms, or headache, chest tightness, palpitations, shortness of breath, and so on.
2. Stage of cardiac decompensation
With the progress of the disease, palpitation, shortness of breath, dyspnea, cyanosis, such as with erythrocytosis, cyanosis will be more obvious; followed by jugular venous anguish, the heart border to both sides of the expansion of the apical region of the 2/6 ~ 3/6 level of blowing wind-like systolic murmur, individual patients can also appear in diastolic murmur, pulmonary valve area of the 2nd tone hyper or with splitting, the lungs heard dry, wet rhonchi, liver enlargement, lower limb edema, pestle finger. Less frequently, some patients may be complicated by upper gastrointestinal bleeding, thrombosis or embolism.
Examination
1. Laboratory tests
The number of red blood cells in the blood is abnormally high. China’s diagnostic criteria for hyperglobinopathy are: hemoglobin>200g/L, hematocrit>65% and erythrocyte count>6.5×1012/L, the total number of leukocytes and their classification are in the normal range; platelets are the same as those of healthy people of the same altitude; the main feature of bone marrow granulocyte system is that the erythrocytic system is proliferating, and red lineage occupies 33.3% of the nucleated cells, and it is especially obvious with the medium- and late-stage erythrocytes, and the granulocyte and megakaryocyte system has no proliferating cells. The granulocyte and megakaryocyte systems showed no significant changes. The pH of patients with hyperthyroidism is lowered by acid-base (pH) measurements. Blood gas analysis showed significant hypoxemia, with decreased PaO2, increased PaCO2, increased A-aDO2, and standard bicarbonate-relative hypercapnia, and pulmonary function was unremarkable except for mild abnormalities in small airway function, which was demonstrated by the patient’s increased closed volume. Exertional expiratory mid-range flow is decreased.
2. Electrocardiogram
Right ventricular hypertrophy is the main manifestation, with rightward deviation of the electrical axis, extreme clockwise rotation, pulmonary P wave or spike-shaped P wave, complete or incomplete right bundle branch block, right ventricular hypertrophy with myocardial strain, etc. Only a few patients have prolongation of P-R and Q-T intervals and biventricular hypertrophy, and right ventricular hypertrophy is positively correlated with pulmonary arterial hypertension.
3. Lung function test
Hypercardiosis and pulmonary heart disease are easy to be confused, and pulmonary function tests are of great value in the identification of the two. Patients with hypercardiosis have only mild small airway dysfunction, which is mainly manifested in the reduction of forceful expiratory flow (FEF25%～75%) and closed air volume (CV/VC%).
4. Doppler echocardiography
Doppler echocardiography is the best non-invasive quantitative diagnosis of pulmonary hypertension. Echocardiography mainly shows dilatation of the right ventricular outflow tract, increase of the right intraventricular diameter, widening of the right ventricular outflow tract without significant changes in the left atrial internal diameter, increase of the ratio of the right ventricular outflow tract to the left atrial internal diameter, and increase of the thickness of the right ventricular anterior wall. The diagnostic criteria for plateau heart disease formulated by the Highland Medical Association of the Chinese Medical Association are: the right ventricular outflow tract is >33mm, and the right ventricular end-diastolic internal diameter is >23mm.
5. X-ray examination
In most patients, increased pulmonary hemorrhage and pulmonary stasis can exist at the same time, and in some cases, the pulmonary hilar shadow is enlarged and the pulmonary texture is increased; the heart changes to convex pulmonary artery segments, conical bulging, and some are even aneurysm-like bulging; the right atrium and/or right ventricle is enlarged, the heart is mitral, the outer diameter of the right lower pulmonary artery is widened, and the right and left ventricles can be enlarged in some individual patients. X-ray diagnostic criteria for hypercardia: transverse diameter of the right lower pulmonary artery trunk >17mm, ratio of the transverse diameter of the right lower pulmonary artery trunk to the transverse internal diameter of the trachea >1.10.
Diagnosis
Diagnostic criteria can be summarized as: ① plateau onset; ② manifestation of pulmonary hypertension; ③ a few severe cases may show left heart damage; ④ exclusion of other congenital and acquired cardiopulmonary diseases; ⑤ lowering the height of the disease retardation. Now we generally agree that diagnostic criteria ①, ④ and ⑤ are the necessary conditions for the diagnosis of plateau heart disease. Academics who hold the first view believe that diagnostic criterion ② is also necessary, and diagnostic criterion ③ is optional. The academics who hold the second view believe that diagnostic criterion ② is optional, while diagnostic criterion ③ is interpreted to mean that the manifestations of left heart involvement are not limited to “a few” and “severe cases”.
Differential diagnosis
1. Congenital heart disease
The prevalence of congenital heart disease, especially arterial ductus arteriosus, is very high in highland areas, and it is easily confused with pediatric hypertrophic heart disease. However, the systolic murmur of arterial ductus arteriosus is rough and conductive, and X-ray examination often has pulmonary portal dance.
2. Pulmonary heart disease
Coronary artery disease and hypercardia are extremely similar in some aspects. However, the former has a history of chronic cough and significant abnormal pulmonary ventilation, while the latter has basically normal pulmonary function.
3. Primary pulmonary hypertension
This disease is rare, with progressive aggravation of the condition, and the condition will not be relieved after leaving the plateau environment.
Treatment
1. General treatment
In addition to the individual difference of hypoxia, exertion, cold and respiratory tract infection are often the triggering factors. Therefore, in the plateau should pay attention to the combination of work and rest, to ensure sleep time and sleep quality, appropriate physical exercise. Cardiac insufficiency should pay attention to bed rest. Adjust the diet, eat more fruits and fresh vegetables, prohibit smoking and excessive alcohol consumption.
2. Oxygen therapy
Oxygen therapy is an important means to correct hypoxia, increase oxygen saturation and improve cardiac function. Oxygen according to the condition of intermittent or continuous low-flow (1L/minute) oxygen, generally do not need to apply high concentration of oxygen, in order to raise the PaO2 to 50mmHg, SaO285% or more appropriate.
3. Cardiotonic and diuretic
Cardiotonic agents can be used for those with heart failure, such as cediran and digoxin. And can be combined with dihydroclonidine, tachycardia and so on.
4.Reduce pulmonary artery pressure
Pulmonary hypertension is the key to the development of hypercardia, can use aminophylline or phentolamine, etc. as appropriate.
5. Antibiotics
Patients with high heart disease are easy to complicate respiratory tract infections, and broad-spectrum or general antibiotics can be used to prevent infections according to the condition.
6. Get out of plateau environment
Where the heart is obviously enlarged, there is obvious pulmonary hypertension and serious cardiac insufficiency should be considered to transfer to the plains or lower altitude treatment.