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Pulmonary Hypertension
renal blood flow. Prolonged hypoxaemia may lead to secondary Pulmonary angiography remains the gold standard test for
polycythemia. An elevated activated partial thromboplastin time may characterising the pulmonary vasculature and is performed to
suggest the possibility of a lupus anticoagulant. While arterial blood ascertain the presence and exact location of thromboembolic disease,
oxygen levels can be normal even in the setting of significant PH, many as well as to determine surgical accessibility. In experienced hands,
patients will experience a decline in PO
2
with exercise. Hypoxaemia in angiography can be performed safely even in severe PH. CTEPH results
the setting of CTEPH is due to ventilation–perfusion (VQ) inequalities, in retraction and partial recanalisation of vessels, resulting in pouch
a reduction in cardiac output causing a decline in mixed venous defects, pulmonary artery webs, areas of focal narrowing (bands),
oxygen saturation and right-to-left shunting of blood through a patent intimal irregularities, abrupt narrowing of major pulmonary arteries
foramen ovale.
19
and obstruction of main, lobar or segmental pulmonary arteries.
22
Focal vessel narrowing can be seen in congenital pulmonic stenosis
Transthoracic echocardiography nearly always reveals some objective and also in medium- or large-vessel arteritis. Complete obstruction or
evidence of PH. Echocardiographic estimation of the right ventricular abrupt narrowing of the central pulmonary arteries can occur from
systolic pressure, evaluation of right-sided chamber size and leftward pulmonary vascular tumours or extravascular compression.
displacement of the intraventricular septum offer evidence of PH and
serve to estimate the severity of the disease.
20
Pulmonary angioscopy is used in a significant minority of patients for
pre-operative evaluation.
23
Angioscopy allows visualisation of the
intima of central pulmonary arteries. Its most useful role appears to be
Chronic thromboembolic disease is
in identifying operative candidates whose angiographic findings
usually bilateral, and unilateral suggest limited disease.
disease should raise suspicion
Surgical Therapy – Pulmonary Thromboendarterectomy
for alternative diagnoses, such as
PTE can substantially improve symptoms, haemodynamics and survival.
tumour, lymphadenopathy and
The majority of patients are World Health Organization (WHO)
functional class III or IV prior to PTE and become class I or II with
fibrosing mediastinitis.
resumption of normal activities after surgery.
After the chest radiograph, spiral computed tomography (CT) is While there have been many reports of the surgical treatment of
probably the most common initial imaging test. CT features CTEPH,
6,16,17,24,25
much of the surgical experience in PTE has been
suggesting CTEPH include evidence of organised thrombus lining reported from the University of California at San Diego Medical Center
the pulmonary vessels, enlargement of the right ventricle and central in the US. Other centres worldwide have increasing experience, but few
pulmonary arteries, variation in size of segmental arteries, bronchial have extensive experience with hundreds of operations performed.
artery collaterals, a mosaic parenchymal perfusion pattern and
changes compatible with infarcts.
21
The absence of these findings does PTE is considered in patients who are symptomatic and have
not rule out surgically correctable disease. impairment of haemodynamics or oxygenation at rest or with exercise.
Pre-operative pulmonary vascular resistance in surgical candidates
Chronic thromboembolic disease is usually bilateral, and unilateral is usually >300dyn/sec/cm
-5
, and most often in the range of
disease should raise suspicion for alternative diagnoses, such as 800–1,000dyn/sec/cm
-5
.
26
tumour, lymphadenopathy and fibrosing mediastinitis. CT is also
useful in characterising co-existent parenchymal lung disease.
Thromboendarterectomy may be
VQ lung scanning plays a pivotal role in determining whether PH is due
to thromboembolism. One or more mismatched segmental or larger
considered in patients with normal or
defects are generally present in CTEPH, while in other causes of PH
nearly normal haemodynamics if
such findings are much less common. Grey zones of relative
vigorous athletic activity is a
hypoperfusion may be present on the perfusion scan, indicating areas
of recanalisation that may underestimate the extent of obstruction.
5
A significant part of their lifestyle.
single mismatched segmental defect in a patient with PH could indicate
CTEPH; thus, the VQ scan is a vital part of the evaluation even when
the CT is unimpressive. CT and VQ scanning are often complementary. Thromboendarterectomy may be considered in patients with normal or
nearly normal haemodynamics if vigorous athletic activity is a
Right heart catheterisation is important in quantitating the severity of significant part of their lifestyle. The sometimes seemingly
the PH as echocardiography is not reliable in this regard. Measurement disproportionate dyspnoea in these individuals is a function of
of oxygen saturations in the vena cava, the right heart chambers and elevated dead space and minute ventilation requirements as well as
the pulmonary artery may document shunting. Coronary angiography inadequate cardiac output with exercise.
and left heart catheterisation may be useful, depending on the
pateint’s history and echocardiographic evaluation. These data are Candidacy for PTE is determined by the location and extent of
important in assessing pre-operative risk when pulmonary proximal thromboembolism. Thrombi must involve the main, lobar
thromboendarterectomy (PTE) is considered. or proximal segmental arteries; disease originating more distally is not
84 EUROPEAN CARDIOLOGY
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