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A Pregnant Woman in the Third Trimester Diagnosed With Acute Respiratory Failure and Severe Lower-Extremity Edema FREE TO VIEW

Mohammad A. Helwani, MD, MSPH; Julianne E. Donnelly, MD; Majesh Makan, MD; Charl J. De Wet, MD
Author and Funding Information

aDepartment of Anesthesiology, Division of Critical Care Medicine and Cardiothoracic Surgery, Washington University in St. Louis, St. Louis, MO

bDivision of Cardiovascular Diseases, Department of Medicine, Washington University in St. Louis, St. Louis, MO

CORRESPONDENCE TO: Mohammad A. Helwani, MD, MSPH, 660 S Euclid Ave, Campus Box 8054, St. Louis, MO 63110


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;150(4):e105-e107. doi:10.1016/j.chest.2016.03.066
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Published online

A previously healthy 33-year-old pregnant woman gravida 4, para 1, with good prenatal care, presented to an obstetric clinic at 34 weeks' gestation with new-onset shortness of breath, activity intolerance, and worsening lower-extremity edema. The patient had had an uncomplicated pregnancy 10 years earlier as well as a remote history of methamphetamine abuse. Pulse oximetry revealed oxygen saturation in the low 80% range with a mild response to oxygen supplementation through a nonrebreather mask. A heparin drip was started because of a concern about pulmonary embolism (PE), and the patient was admitted to the ICU for further management.

In the ICU, vital signs were BP of 92/58 mm Hg, heart rate of 90 beats/min, respiratory rate of 22 breaths/min, with oxygen saturation of 94% using a 15 L/min nonrebreather mask. Physical examination revealed tachypnea, tachycardia, jugular venous distention, muffled heart sounds, and decreased breath sounds. Arterial blood gas determination showed respiratory alkalosis and marked hypoxemia with a pH of 7.45, Pco2 of 21 mm Hg, and Po2 of 68 mm Hg. Chest radiography showed clear lungs and dilated pulmonary arteries. Electrocardiography demonstrated an incomplete right bundle branch block and evidence of right ventricular (RV) hypertrophy. Urgent transthoracic echocardiography was performed (Video 1).

Question: After reviewing the history, physical examination findings, and ultrasonographic videos, what is the most likely differential diagnosis?

Answer: Transthoracic echocardiography (TTE) revealed a small D-shaped left ventricle with normal systolic function and severe RV and right atrial dilatation with moderate RV hypokinesis and an estimated pulmonary systolic pressure of 75 mm Hg. TTE suggested both volume overload (bowing of the intraventricular septum toward the left ventricle in diastole) and pressure overload of the right ventricle (flattening of the septum during systole).

The cause of the patient’s pulmonary hypertension (PH) was thought to be idiopathic and related to the remote use of methamphetamine or secondary to a PE. The PE was not conclusively ruled out because a spiral CT scan with IV contrast was not obtained because of her pregnancy, and as the patient was in acute distress, she was not able to lie flat for imaging. A lower-extremity Doppler scan was negative for deep venous thrombosis. The perfusion scan showed patchy decreased perfusion in upper lobes but no large perfusion defect (intermediate likelihood ratio for PE). Based on the acute presentation, the possibility of intracardiac shunting was not considered at this time.

A pulmonary artery (PA) catheter was placed, and IV epoprostenol and dobutamine was started to treat the elevated PA pressure and support RV function. A consultation with multiple disciplines, including cardiac surgery, cardiology, pulmonology, fetal medicine, obstetrics, and cardiac anesthesiology, was convened. It was decided to proceed with cesarean delivery with the patients under general anesthesia in the cardiac operating room with extracorporeal membrane oxygenation available in the event of cardiorespiratory collapse.

In the operating room, access for possible extracorporeal membrane oxygenation was gained in bilateral groin areas with the patient under mild sedation. Induction of general anesthesia resulted in hypotension, which was treated with boluses and infusion of epinephrine and norepinephrine. After intubation, an intraoperative TEE probe was inserted and IV epoprostenol was switched to inhaled epoprostenol and nitric oxide. TEE revealed a large secundum atrial septum defect (ASD), with bidirectional flow not previously seen on TTE (Videos 2-5).

This patient presented with respiratory failure and PH with RV overload and was ultimately diagnosed with a large secundum ASD with bidirectional shunting. On initial presentation, she was considered to have RV dysfunction and hypoxemia related to pulmonary vascular disease from methamphetamine use. We also considered intrapulmonary shunting from atelectasis secondary to the term pregnancy as a contributing factor. However, the sudden onset of symptoms together with significant RV dilatation caused concern for an acute PE. The patient was therefore treated empirically with heparin for PE and the decision was made to urgently deliver the fetus (Video 6, Discussion video).

This case demonstrates the limitations of TTE in the diagnosis of ASD and the importance of including it in the differential diagnosis of a patient presenting with PH and RV overload/dysfunction.

Features of an ASD on two-dimensional TTE include abrupt discontinuity and hypermobility of the septum. Initial imaging of the interatrial septum (IAS) may be inconclusive, especially in the apical four-chamber view. In this view with the septum in the far field, echo dropout is common because of the parallel orientation of the echo beam and the thinness of the IAS at the fossa ovalis. The IAS is often best visualized in the subcostal view, in which the ultrasound beam is generally nearly perpendicular to the atrial septum. However, this view would be suboptimal in individuals with obesity or pregnancy.

Indirect evidence of an ASD includes signs of right-sided volume overload. These include right atrial and ventricular enlargement due to volume overload, interventricular septal flattening during diastole, increased PA velocities (without anatomic stenosis), and PA dilatation due to increased pulmonary flow.

Doppler scanning helps confirm the presence of ASD and evaluates flow across the defect. Color-flow Doppler estimates the size and evaluates the flow direction. A jet width greater than 15 mm in adults can distinguish patients with a shunt ratio of > 2:1 and indicates the need for ASD closure. Limitations to color-flow Doppler include ghosting of color across the IAS that may give a false impression of an ASD. A shunt may be missed because of a high Nyquist limit, misinterpreting nonturbulent flow across the IAS as vena caval inflow, or due to a very brief flow time during the cardiac cycle. Pulsed-wave Doppler permits sampling of blood flow velocities and flow across the defect. It also could be used to estimate the pulmonary to systemic flow ratio. Continuous-wave Doppler is useful for higher-velocity flows and for estimating the PA pressure using the modified Bernoulli equation. Agitated saline contrast with the Valsalva maneuver is helpful to confirm the diagnosis but is not routinely done unless shunting is suspected. A bubble study with agitated saline was not performed because of the pregnancy and since an intracardiac shunt was not suspected due to the acute presentation. Contrast media could help in evaluating shunting across the IAS, but it is not used in pregnancy due to safety concerns. TEE is superior to TTE for the diagnosis of ASD, as the IAS lies close to the transducer and is separated by the blood-filled left atrium acting as a superb acoustic window. TEE is indicated when TTE is imaging is limited to evaluate for an anomalous pulmonary venous connection or the possibility of a sinus venosus ASD. TEE, particularly three-dimensional echocardiography, can more precisely assess the size of the ASD and guide planning for closure.,

ASD is a common congenital heart lesion, repaired or unrepaired, occurring in nonpregnant and pregnant women. Secundum ASD is the most common type of ASD (75% of cases) and is positioned by the fossa ovalis. The pathophysiology of ASDs depends on the size of the defect and the relationship of pulmonary and systemic resistance and compliance. Pregnancy is generally well tolerated, with no maternal or fetal morbidities. However, with pregnancy, women with large shunts and PH may experience worsening of supraventricular arrhythmias, progression of PH, and RV failure. Severe PH (Eisenmenger syndrome) results from advanced pulmonary arterial disease with right to left shunting and cyanosis, and it is a contraindication to pregnancy because of high maternal and fetal mortality.,

An important concern about ASD is paradoxical embolization and hypoxemia. The risk of paradoxical embolization from the leg or pelvic veins should be minimized in pregnant patients. Paradoxical air emboli should be minimized by using filters on all IV lines. The substantial increase in intravascular volume results in an increase in cardiac output, which potentiates the risk of life-threatening RV failure.

In the patient in our study, the decrease in systemic vascular resistance and the increase of intravascular volume in the third trimester provoked a right to left shunt and caused hypoxemia.

The best maternal and fetal outcomes are contingent on early diagnosis and a multidisciplinary approach to management.

Cesarean section was performed in the patient in our study and the infant was delivered safely. At the conclusion of the procedure, the patient was transferred in critical but stable condition to the cardiothoracic ICU. Later, she was discharged home with epoprostenol, tadalafil, midodrine, and furosemide. She continues to be followed and evaluated for ASD closure by the PH team.

  • 1.

    The intensivist may encounter patients with unexplained RV overload/dysfunction; obscured ASD should be ruled out.

  • 2.

    TTE may not clearly show the IAS. A secundum ASD may be missed in the apical four-chamber view. Using agitated saline and color-flow Doppler is helpful in confirming the diagnosis.

  • 3.

    Because of a decrease in peripheral resistance, increased cardiac output, and progression of PH during pregnancy, patients with ASDs may present with right to left shunting and right-sided heart overload/dysfunction.

Financial/nonfinancial disclosures: None declared.

Other contributions:CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.

Additional information: To analyze this case with the videos, see the online version of this article.

Martin S.S. .Shapiro E.P. .Mukherjee M. . Atrial septal defect—clinical manifestation, echo assessment, and intervention. Clin Med Insights Cardiol. 2014;8:93-98 [PubMed]journal
 
Shub C. .Dimopoulos I.N. .Seward J.B. .et al Sensitivity of two-dimensional echocardiography in the direct visualization of atrial septal defect utilizing the subcostal approach: experience with 154 patients. J Am Coll Cardiol. 1983;2:127-135 [PubMed]journal. [CrossRef] [PubMed]
 
Pollick C. .Sullivan H. .Cujec B. .Wilansky S. . Doppler color-flow imaging assessment of shunt size in atrial septal defect. Circulation. 1988;78:522- [PubMed]journal. [CrossRef] [PubMed]
 
Warnes C.A. .Williams R.G. .Bashore T.M. .et al ACC/AHA 2008 Guidelines for the Management of Adults with Congenital Heart Disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to develop guidelines on the management of adults with congenital heart disease). Circulation. 2008;118:e714-e833 [PubMed]journal. [CrossRef] [PubMed]
 
Konstantinides S. .Kasper W. .Geibel A. .et al Detection of left-to-right shunt in atrial septal defect by negative contrast echocardiography: a comparison of transthoracic and transesophageal approach. Am Heart J. 1993;126:909-917 [PubMed]journal. [CrossRef] [PubMed]
 
Roberson D.A. .Cui W. .Patel D. .et al Three-dimensional transesophageal echocardiography of atrial septal defect: a qualitative and quantitative anatomic study. J Am Soc Echocardiogr. 2011;24:600-610 [PubMed]journal. [CrossRef] [PubMed]
 
Weiss B.M. .Zemp L. .Seifert B. .Hess O.M. . Outcome of pulmonary vascular disease in pregnancy: a systematic overview from 1978 through 1996. J Am Coll Cardiol. 1998;31:1650-1657 [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Tables

References

Martin S.S. .Shapiro E.P. .Mukherjee M. . Atrial septal defect—clinical manifestation, echo assessment, and intervention. Clin Med Insights Cardiol. 2014;8:93-98 [PubMed]journal
 
Shub C. .Dimopoulos I.N. .Seward J.B. .et al Sensitivity of two-dimensional echocardiography in the direct visualization of atrial septal defect utilizing the subcostal approach: experience with 154 patients. J Am Coll Cardiol. 1983;2:127-135 [PubMed]journal. [CrossRef] [PubMed]
 
Pollick C. .Sullivan H. .Cujec B. .Wilansky S. . Doppler color-flow imaging assessment of shunt size in atrial septal defect. Circulation. 1988;78:522- [PubMed]journal. [CrossRef] [PubMed]
 
Warnes C.A. .Williams R.G. .Bashore T.M. .et al ACC/AHA 2008 Guidelines for the Management of Adults with Congenital Heart Disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to develop guidelines on the management of adults with congenital heart disease). Circulation. 2008;118:e714-e833 [PubMed]journal. [CrossRef] [PubMed]
 
Konstantinides S. .Kasper W. .Geibel A. .et al Detection of left-to-right shunt in atrial septal defect by negative contrast echocardiography: a comparison of transthoracic and transesophageal approach. Am Heart J. 1993;126:909-917 [PubMed]journal. [CrossRef] [PubMed]
 
Roberson D.A. .Cui W. .Patel D. .et al Three-dimensional transesophageal echocardiography of atrial septal defect: a qualitative and quantitative anatomic study. J Am Soc Echocardiogr. 2011;24:600-610 [PubMed]journal. [CrossRef] [PubMed]
 
Weiss B.M. .Zemp L. .Seifert B. .Hess O.M. . Outcome of pulmonary vascular disease in pregnancy: a systematic overview from 1978 through 1996. J Am Coll Cardiol. 1998;31:1650-1657 [PubMed]journal. [CrossRef] [PubMed]
 
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