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an expert centre. There a final decision regarding suitability for surgical resection will be made, and no patient should be denied an operation without an expert surgical centre determining that the patient is inoperable.

An echocardiogram is often the initial diagnostic test in the work-up of a patient undergoing evaluation for CTEPH. The echo will usually suggest PH, with a rapid tricuspid regurgitant jet suggesting elevated pulmonary arterial pressures. The right ventricle tends to be enlarged and hypokinetic. Left ventricular and valvular function are usually normal. A contrast bubble study should be performed to rule out a patent foramen ovale (PFO), which is common and could be closed at the time of surgical endarterectomy.7

diagnosis. In fact, there is a median of 14 months of symptoms before a diagnosis is made. Dyspnoea is a ubiquitous symptom present in 99% of patients. Most patients will be in New York Heart Association (NYHA) class III or IV, by the time a diagnosis is reached.6

The majority 28

(50–70%) have a previous history of venous thromboembolism; however, a substantial minority, give no such previous history, and the first evidence of thromboembolic disease is discovered during abnormal imaging while being worked-up for PH. Other common symptoms include chest pain, which may be central or pleuritic. It is often not typically anginal in nature although likely represents right ventricular demand. Palpitations are common, as is peripheral oedema. The nature of the oedema may be multi-factorial with right ventricular dysfunction, chronic venous obstruction and post-thrombotic syndrome all contributing. Exertional dizziness and syncope can be late presentations of this disease, a manifestation of inadequate right ventricular cardiac output. Another late, but potentially deadly, presentation can be haemoptysis. This is usually bronchial in nature, and results from a hypertrophied bronchial circulation that occurs with chronic obstruction of the pulmonary arteries.

On physical exam, the presenting features tend to be similar to those of other causes of PH. Vital signs can reveal a resting tachycardia, and often a mild decrease in oxygen saturation. Cardiovascular examination reveals signs of PH and right ventricular dysfunction. A loud pulmonic component of the second heart sound is frequently present, as are a right ventricular heave, elevated jugular veins and peripheral oedema. A unique physical exam finding that is sometimes present in CTEPH, and is absent in other forms of PH, is a pulmonary arterial bruit that is caused by turbulent flow through the partially obstructed main pulmonary arteries.

Diagnostic work-up

The diagnostic work-up for CTEPH comprises two parts: making the diagnosis of CTEPH; and deciding on surgical resectability. The decision regarding surgical accessibility of clots is one that is very dependent on the experience and expertise of the surgeon and the centre performing the procedure. There are no established guidelines or criteria that help establish surgical resectability.

After a diagnosis of CTEPH is made, the patient should always be assessed at

A ventilation perfusion nuclear lung scan (V/Q) remains, in most expert opinion, the diagnostic test of choice in patients being worked-up for CTEPH. It may be performed as part of the evaluation of PH after an echo suggests PH, or it may be performed in a patient who remains symptomatic after an acute PE. A normal perfusion scan, without evidence of significant perfusion mismatches in a patient with PH essentially rules out the diagnosis of CTEPH.6,8

A positive V/Q scan in a

patient with CTEPH is highly suggestive but not diagnostic of the disorder. Other rare disorders can cause PH and a positive lung scan, including fibrosing mediastinitis, pulmonary veno-occlusive disease, sarcoidosis and rare tumours of the pulmonary arterial tree, such as pulmonary artery sarcoma.9

As previously mentioned, CTEPH is a notoriously underdiagnosed entity. Many patients do not normalise their perfusion after an acute PE. A case could be made to perform routine V/Q scans in patients three to six months after their acute event, especially those who remain symptomatic, to screen for this disorder, although no such guidelines or recommendations yet exist.

A CT pulmonary angiogram (CTPA) is another necessary diagnostic step in the evaluation of a patient for CTEPH. Although in many institutions CTPA has supplanted V/Q scanning as the initial diagnostic test of choice for acute PE, in chronic disease, V/Q remains more sensitive.8

The findings on CTPA in

CTEPH differ widely from those in acute PE because the clot becomes fibrosed, remodelled and intra-mural. The main

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