Is pulmonary embolism a common cause of chronic pulmonary hypertension? Limitations of the embolic hypothesis. P Egermayer, A.J. Peacock. #ERS Journals Ltd 2000. ABSTRACT: The hypothesis that chronic thromboembolic pulmonary hypertension results from unresolved pulmonary embolism has strongly influenced the diagnosis and management of this disease since the 1960s. However, it is nearly impossible to induce chronic pulmonary hypertension in any animal species by means of repeated embolization of thrombotic material. The haemodynamic effects of thrombotic pulmonary embolism of different degrees of magnitude have also been studied in humans and there is little to suggest that chronic pulmonary hypertension is a likely long term outcome. Furthermore many conditions which predispose to venous thromboembolism do not appear to cause thromboembolic pulmonary hypertension. Other arteriopathic and atherosclerotic risk factors, are found in patients with chronic thromboembolic pulmonary hypertension, but not in those with venous thrombosis, suggesting that these may be unrelated conditions.Thrombosis in situ of the pulmonary arteries is common in severe pulmonary hypertension of any cause. Such thrombosis cannot usually be distinguished from pulmonary embolism. It is hypothesized that in situ thrombosis and pulmonary arteriopathy are common causes of vascular occlusion which is usually diagnosed as "chronic thromboembolic pulmonary hypertension" and that venous thromboembolism is unlikely to be a common cause of chronic pulmonary hypertension. It is further hypothesized that pulmonary embolism is seldom the sole cause of "chronic thromboembolic pulmonary hypertension". Eur Respir J 2000; 15: 440±448.
Background-A study was undertaken to assess the usefulness of the SimpliRED D-dimer test, arterial oxygen tension, and respiratory rate measurement for excluding pulmonary embolism (PE) and venous thromboembolism (VTE). Methods-Lung scans were performed in 517 consecutive medical inpatients with suspected acute PE over a one year period. Predetermined end points for objectively diagnosed PE in order of precedence were (1) a post mortem diagnosis, (2) a positive pulmonary angiogram, (3) a high probability ventilation perfusion lung scan when the pretest probability was also high, and (4) the unanimous opinion of an adjudication committee. Deep vein thrombosis (DVT) was diagnosed by standard ultrasound and venography. Results-A total of 40 cases of PE and 37 cases of DVT were objectively diagnosed. The predictive value of a negative SimpliRED test for excluding objectively diagnosed PE was 0.99 (error rate 2/249), that of PaO 2 of >80 mm Hg (10.7 kPa) was 0.97 (error rate 5/160), and that of a respiratory rate of <20/min was 0.95 (error rate 14/308). The best combination of findings for excluding PE was a negative SimpliRED test and PaO 2 >80 mm Hg, which gave a predictive value of 1.0 (error rate 0/93). The predictive value of a negative SimpliRED test for excluding VTE was 0.98 (error rate 5/249). Conclusions-All three of these observations are helpful in excluding PE. When any two parameters were normal, PE was very unlikely. In patients with a negative SimpliRED test and PaO 2 of >80 mm Hg a lung scan is usually unnecessary. Application of this approach for triage in the preliminary assessment of suspected PE could lead to a reduced rate of false positive diagnoses and considerable resource savings. (Thorax 1998;53:830-834) Keywords: pulmonary embolism; deep vein thrombosis; D-dimer; blood gas; respiratory rate Pulmonary embolism (PE) and deep vein thrombosis (DVT) are disorders of importance in most areas of medicine. The clinical presentation of PE is notoriously non-specific and may mimic many other acute cardiorespiratory illnesses. In cases of suspected PE the ventilation perfusion (VQ) lung scan is a commonly requested examination. A normal VQ scan eVectively excludes PE, and a high probability VQ scan in an appropriate clinical setting oVers good but not incontrovertible evidence that PE has occurred.1 However, in practice up to 70% of lung scans show non-specific abnormalities, and additional tests, including pulmonary angiography, are often required.2 Furthermore, the VQ scan is a relatively expensive and technology dependent screening procedure, and more selective utilisation of this test has been advocated. 3 For example, the recently published British Thoracic Society guidelines suggested that a normal D-dimer level (measured by ELISA) excludes PE, as does a respiratory rate of <20/min and the absence of pleuritic pain and hypoxaemia. 4 These suggestions, while plausible, remain relatively untested.D-dimer is a product of fibrinolysis. Levels of D-dimer are raised in many conditions incl...
Abstract. Egermayer P (Canterbury RespiratoryResearchEpidemics of vascular disease caused by toxins and infectious agents affecting both humans and animals have been common in history. Examples of agents implicated include anorexients, ergotamine, mercury, arsenic, vinyl chloride, thorotrast, plant alkaloids, nitrites, toxic oil, tryptophan and bacterial, viral and parasitic infections. A major characteristic of these disorders is endothelial dysfunction, which may manifest itself in vasospastic disorders, sclerodermiform skin lesions, fibrosis, osteolytic lesions, polyneuropathy and portal and pulmonary hypertension. Angiosarcoma may also be a late outcome. These diseases are more common than is generally appreciated. The aetiology is usually multifactorial. This and other factors contribute to delayed recognition.
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