Acute pulmonary embolus in pregnancy: a case study highlighting the value of TTE
Department of Cardiology, Westmead Hospital, Hawkesbury Road, Westmead, NSW 2145, Australia
Received 13 November 2006; accepted after revision 11 March 2007; online publish-ahead-of-print 11 May 2007.
* Corresponding author. Tel: +61 (02) 9845 6795. E-mail address: lizat{at}westgate.wh.usyd.edu.au (L. Thomas).
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Abstract |
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In pregnancy, the incidence of pulmonary embolism (PE) is increased fivefold when compared to non-pregnant women of the same age, and PE is one of the leading causes of death during pregnancy. However, the diagnosis of PE among pregnant women is complicated by concerns regarding radiation exposure. We report the case of a 36-year-old woman at 9 weeks gestation with an acute PE that highlights the value of transthoracic echocardiography in diagnosis, for initial and on-going treatment in such a setting, while keeping doses of radiation low.
Keywords: Transthoracic echocardiography; Pulmonary embolism
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Case study |
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A 36-year-old woman at 9 weeks gestation presented to the emergency department with central tight chest pain. She had a history of a previous miscarriage, but no history of prior cardiovascular disease. On examination she was in sinus rhythm with a pulse rate of 75 bpm, her oxygen saturation was 96% and she was normotensive.
Transthoracic echocardiography (TTE) showed a moderately dilated right atrium (RA) and right ventricle (RV), with normal right ventricular function. The atrial septum bowed persistently to the left and the left atrium was compressed. Interventricular septal flattening in diastole (Figure 1A), consistent with an elevated right heart pressure was observed. Moderate tricuspid regurgitation with a peak velocity of 3.9 m/s was recorded (Figure 1B). Right atrial pressure was estimated to be 10 mmHg as the IVC was dilated but collapsed, and right ventricular systolic pressure was calculated to be 60 mmHg. The patient was diagnosed to have severe pulmonary hypertension.
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A Doppler ultrasound study of her legs revealed a 5 cm thrombus in the distal right superficial femoral vein. Pulmonary embolism was considered to be the most likely cause of her pulmonary hypertension. Her ANA result was 80 (reference range <80); all other blood results including a factor 5 Leiden mutation test were normal. Given the pregnancy, computerised tomography pulmonary angiography (CTPA) and ventilation–perfusion (V/Q) lung scans were not performed. She was treated initially with an infusion of unfractionated heparin that was later changed to Clexane prior to discharge.
A follow up TTE, 2 weeks later, revealed complete resolution of the pulmonary hypertension (Figure 2A and B). The RA and RV were normal in size, the interatrial septum was midline and there was mild tricuspid regurgitation with a normal pulmonary artery systolic pressure estimated to be 20 mmHg.
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Discussion |
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Pulmonary hypertension (PHT) may occur as either a primary process or secondary to another disease. Among the secondary causes of PHT is pulmonary embolism (PE), a blockage of a pulmonary artery most often by a thrombus, arising from one of the deep leg veins.
Clinically PE is characterised by dyspnoea, tachycardia, sudden chest pain and shock. Cyanosis may occur in cases of massive PE. The predisposing factors include increased coagulopathy, immobilisation, trauma to blood vessels and pregnancy.1 However, the diagnosis of PE is often difficult and sometimes missed, leading to higher mortality rates. Furthermore, the rate of PE in pregnancy is increased five times when compared to non-pregnant women of the same age, and PE is one of the leading causes of death during pregnancy.2,3 Therefore, early diagnosis and prompt treatment of PE is imperative.
CTPA is usually the gold standard for diagnosing PE. However, because of concerns regarding the radiation dose received, particularly to the foetus, other means of diagnosis may be necessary for pregnant women with clinical signs of PE.2 In the emergency setting TTE is simple and findings are quickly obtained. Its value in helping monitor treatment response is established, and recent data also reveal that TTE combined with venous ultrasound improves the diagnostic value.4
Results of a study published by Mansencal et al. show that RVED-to-LVED area ratio (measured in the apical 4 chamber view), with a cut-off value of >0.6, is the most accurate echocardiographic index of right ventricular obstruction in acute PE.5 In our case study, when this criterion was applied, a measurement >0.6 was obtained; this along with the other findings pointed to a significant PE. Moreover, simple 2D indexes relative to MRI, have been shown to be preferable to 3D echocardiography and SPECT in the evaluation of right ventricular function.6
More recently, cardiac biomarkers such as N-terminal pro-brain natriuretic peptide and heart-type fatty acid-binding protein have emerged as promising and relatively simple prognostic indicators in comparison to nuclear imaging in patients with acute PE. Additionally, their prognostic value is complemented by echocardiography.7,8
In conclusion, the diagnosis of PE among pregnant women is complicated by concerns regarding radiation exposure. Our case study highlights why TTE is useful in such cases; in an emergency setting TTE is simple, quick to perform and complements both venous ultrasound and other findings from routine diagnostic procedures. Established 2D echocardiographic criteria of RVED-to-LVED area ratio aid in early diagnosis and prompt treatment, and may be increasingly useful if combined with cardiac biomarker levels to assess the extent of PE and in prognosis. Furthermore, TTE provides baseline measurements that can be used to monitor the patients' response to treatment, and is compatible with an approach of keeping radiation doses ‘as low as reasonably achievable’ in pregnancy.
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References |
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- Piazza G, Goldhaber S. Acute pulmonary embolism: part 1: epidemiology and diagnosis. Circulation (2006) 114:28–32.[CrossRef]
- Matthews S. Imaging pulmonary embolism in pregnancy: what is the most appropriate imaging tool? Radiol (2006) 79:441–4.
- Gissler M, Dereux-Tharaux C, Alexander S, Berg S, Bouvier-Colle MH, Harper M, et al. Pregnancy-related deaths in four regions of Europe and the United States in 1999–2000: characterisation of unreported deaths. Eur Obstet Gynaecol Reprod Biol (2007) 133:179–85.[CrossRef]
- Mansencal N, Redheuil A, Joseph T, Viellard-Baron A, Jordeau G, Lacombe P, et al. Use of TTE combined with venous ultrasound in patients with pulmonary embolism. Int Cardiol (2004) 96:59–63.[CrossRef]
- Mansencal N, Joseph T, Viellard-Baron A, Qanalde S, Jordeau G, Lacombe P, et al. Comparison of different echocardiographic indexes secondary to right ventricular obstruction in acute pulmonary embolism. Am J Cardiol (2003) 92:116–9.[CrossRef][Web of Science][Medline]
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- Binder L, Pieske B, Olschewski M, Geibel A, Klostermann B, Reiner C, et al. N-terminal pro-brain natriuretic peptide or troponin testing followed by echocardiography for risk stratification of acute pulmonary embolism. Circulation (2005) 112:1573–9.
[Abstract/Free Full Text] - Puls M, Dellas C, Lankeit M, Olschewski M, Lutz B, Giebel A, et al. Heart-type fatty acid-binding protein permits early risk stratification of pulmonary embolism. Eur Heart J (2007) 28:224–9.
[Abstract/Free Full Text]
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