Chronic Thromboembolic Pulmonary Hypertension
Pulmonary embolism (PE) is a common life-threatening disease early after its occurrence with a late high mortality rate linked to underlying comorbidities, especially cancer and cardiopulmonary diseases. Morbidity after PE comprises a high recurrence rate in patients with permanent risk factors or idiopathic disease or, less frequently, in conditions linked to unresolved PE that lead to pulmonary hypertension and is thus termed chronic thromboembolic pulmonary hypertension (CTEPH).
Chronic thromboembolic pulmonary disease is a cause of pulmonary hypertension. The condition is defined by the absence of thrombus resolution after one or more episodes of acute pulmonary embolic event that causes sustained obstruction of the pulmonary arteries and subsequent pulmonary hypertension. The extent of vascular obstruction is a major determinant of chronic thromboembolic pulmonary hypertension (CTEPH). However, in many patients, disease progression involves pulmonary vascular remodelling and the development of a specific pulmonary arteriopathy in the non-obstructed pulmonary vessels.
The presence of thrombotic risk factors, such as antithrombin III, protein C, or protein S activity, as well as factor II and factor V Leiden mutations was not different between CTEPH and primary pulmonary hypertension. However, antiphospholipid antibodies and elevated levels of factor VIII are seen more commonly in CTEPH patients, which suggest that an underlying hypercoagulable state may be responsible for CTEPH.
Defective fibrinolytic systems.
- Presence of lupus-like anticoagulant.
- Deficiency of protein C, protein S, and antithrombin III.
- Atrial septal defects.
- Indwelling venous catheters.
Progressive exertional dyspnea
- Exercise intolerance.
- Pulmonic component of the second heart sound.
- Chest pain on exertion.
- Inability of a compromised right ventricle to meet the body's demands for CO.
Loud second heart sound.
- Tricuspid regurgitation murmurs.
- Engorged liver and neck veins.
- Elevated jugular pressure with a positive hepatojugular reflex.
- The presence of peripheral oedema.
- Peripheral and central cyanosis.
- Prominent right ventricular impulse.
CTEPH is usually suspected in patients with unexplainedexertional dyspnea. At first visit, ECG data(suggestive of right ventricular dysfunction such as anegative T wave in the precordial leads V1-V4) or chestX-ray (right descending pulmonary artery diameter> 20 mm or an avascular area with pleuritic change)may reinforce the hypothesis. A confirmation of pulmonaryarterial hypertension then comes fromtransthoracic echocardiography. Finally the obstructivenature of the disease is shown by ventilation-perfusionlung scan identifying one or more mismatched defects.However, the perfusion lung scan often underestimatespulmonary vascular obstruction which is better describedat angiography. Pulmonary angiography isconsidered the “gold standard” for the evaluation ofCTEPH and CT scan cannot substitute pulmonaryangiography in the diagnosis of CTEPH. In fact, anormal CT scan does not exclude the diagnosis ofCTEPH. However, CT scan may be useful to evaluatethe status of pulmonary parenchyma and to rule outconfounding disorders determining unilateral obstructionsuch as pulmonary artery sarcoma, vasculitis, canceror mediastinal fibrosis.
All patients with CTEPH should receive lifelong anticoagulation prophylaxis with warfarin to prevent recurrent thromboembolic events, but regression of pulmonary hypertension due to anticoagulation therapy is unlikely. In patients with mild disease (i.e., mild pulmonary hypertension, little to no clinical impairment, and normal RV function), watchful waiting and anticoagulation are recommended. However, the definitive treatment of patients with symptomatic CTEPH is surgical.
CTEPH is the only cause of severe pulmonary hypertension which is potentially curable without the need to resort to lung transplantation. Pulmonary endarterectomy (PEA) is the surgical procedure which removes the obstructing thromboembolic material, resulting in significant improvements (and in many cases normalization) in right ventricular haemodynamics and function. This procedure requires a high degree of anaesthetic and surgical skill, coupled with assiduous preoperative evaluation of potential patients. Surgery is generally considered only in patients with proximal chronic thromboembolic disease as assessed by radiological investigations.
Chronic thromboembolic pulmonary hypertension is ideally treated with pulmonary thromboendarterectomy. The thromboembolic material, the intima, and a variable portion of the media are removed with the endarterectomy specimen; thus, the procedure is not simply embolectomy. Most patients with CTEPH who undergo thromboendarterectomy improve clinically in terms of gaseous exchange and pulmonary haemodynamics. When all surgical procedures are contraindicated, medical therapies such as long term anticoagulants, diuretics, vasodilators, inotropes, and oxygen therapy remain other options, but medical treatment is not considered curative.
For extreme situations the ultimate treatment is lung transplantation.
In conclusion, CTEPH is a rare but treatable disorder, in which early diagnosis can be achieved with a high index of clinical suspicion and the use of helical CT and V/Q scans.
The following tests, drugs and medications, surgical procedures are in some way related to, or used in the treatment. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
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