December 2016 Imaging Case of the Month

Eric A. Jensen, MD

Michael B. Gotway, MD 

Department of Radiology

Mayo Clinic Arizona

Scottsdale, AZ USA

Imaging Case of the Month CME Information  

Members of the Arizona, New Mexico, Colorado and California Thoracic Societies and the Mayo Clinic are able to receive  0.25 AMA PRA Category 1 Credits™. Completion of an evaluation form is required to receive credit and a link is provided on the last panel of the activity.

0.25 AMA PRA Category 1 Credit(s)™

Estimated time to complete this activity: 0.25 hours

Lead Author(s): Eric A. Jensen, MD. All Faculty, CME Planning Committee Members, and the CME Office Reviewers have disclosed that they do not have any relevant financial relationships with commercial interests that would constitute a conflict of interest concerning this CME activity. 

Learning Objectives:
As a result of this activity I will be better able to:    

1. Correctly interpret and identify clinical practices supported by the highest quality available evidence.
2. Will be better able to establsh the optimal evaluation leading to a correct diagnosis for patients with pulmonary, critical care and sleep disorders.
3. Will improve the translation of the most current clinical information into the delivery of high quality care for patients.
4. Will integrate new treatment options in discussing available treatment alternatives for patients with pulmonary, critical care and sleep related disorders.

Learning Format: Case-based, interactive online course, including mandatory assessment questions (number of questions varies by case). Please also read the Technical Requirements.

CME Sponsor: University of Arizona College of Medicine at the Arizona Health Sciences Center.

Current Approval Period: January 1, 2015-December 31, 2016

Clinical History: A 47-year-old woman presented for medical evaluation prior to trans-sphenoid hypophysectomy for pituitary adenoma for Cushing syndrome. The patient had an extensive past medical history, including kidney minimal change disease treated with corticosteroids between 5-7 years previously (no longer on corticosteroid therapy), type II diabetes mellitus, focal segmental glomeruloscleroosis on renal biopsy, morbid obesity, gout, obstructive sleep apnea on continuous positive airway pressure (CPAP) supplemented with oxygen for the previous 8 years, hypertension, and recent-onset atrial fibrillation, as well as a history of several pneumonias, perhaps related to chronic immunosuppression. Her past surgical history included bilateral partial knee replacement, lower extremity vein ablation, and breast reduction. Her medication list was extensive, including allopurinol, anti-hypertensives, anti-depressants, colchicine, oxygen, and Tacrolimus, among others, including over-the-counter medications.

Laboratory data, include white blood cell count, coagulation profile, and serum chemistries were within normal limits. Oxygen saturation on room air was 95%.

Frontal and lateral chest radiographs (Figure 1) were performed. A previous chest radiograph performed 2 years earlier is presented for comparison (Figure 2).

Figure 1. Frontal (A) and lateral (B) chest radiography.

Figure 2.  Frontal chest radiography performed 2 years prior to presentation.

Which of the following statements regarding the chest radiograph is most accurate? (Click on the correct answer to proceed to the second of seven pages)

1. Frontal and lateral chest radiography appears normal
2. Frontal and lateral chest radiography shows a mass projected over the right paratracheal region
3. Frontal and lateral chest radiography shows asymmetric hyperlucency affecting the right thorax
4. Frontal and lateral chest radiography shows basal reticulation suggesting possible fibrotic disease
5. Frontal and lateral chest radiography shows cardiomegaly only, but is unchanged from prior

Cite as: Jensen EA, Gotway MB. December 2016 imaging case of the month. Southwest J Pulm Crit Care. 2016;13(6):290-301. doi: https://doi.org/10.13175/swjpcc135-16 PDF 

Medical Image of the Week: Pulsus Alternans

Figure 1. Telemetry display including arterial pressure waveform, which demonstrates alternating beats of large (large arrows) and small (small arrows) pulse pressure. Concurrent pulse oximetry could not be performed at the time of the image due to poor peripheral perfusion.

A 52 year old man with a known past medical history of morbid obesity (BMI, 54.6 kg/m²), heart failure with preserved ejection fraction, hypertension, untreated obstructive sleep apnea, and obesity hypoventilation syndrome presented with increasing dyspnea over several months accompanied by orthopnea and weight gain that the patient had treated at home with a borrowed oxygen concentrator. On arrival to the Emergency Department, the patient was in moderate respiratory distress and hypoxic to SpO2 70% on room air. Physical examination was pertinent for pitting edema to the level of the chest. Assessment of jugular venous pressure and heart and lung auscultation were limited by body habitus, but chest radiography suggested pulmonary edema. The patient refused aggressive medical care beyond supplemental oxygen and diuretic therapy. Initial transthoracic echocardiography was limited due to poor acoustic windows but suggested a newly depressed left ventricular ejection fraction (LVEF) of <25%. The cause, though uncertain, may have been reported recent amphetamine use. The patient deteriorated, developing shock and respiratory failure; after agreeing to maximal measures, ventilatory and inotropic/vasopressor support was initiated.

Shortly after placement of the arterial catheter, the ICU team was called to the bedside for a change in the arterial pressure waveform (Figure 1), which then demonstrated alternating strong (arrow) and weak beats (arrow head) independent of the respiratory cycle. The waveform was recognized as pulsus alternans. Repeat bedside echocardiography suggested severe biventricular systolic impairment and LVEF of approximately 5-10%, later confirmed by formal transesophageal ehocardiography performed prior to a cardioversion for atrial flutter.

Pulsus alternans was first formally described in 1872 and associated with severe left ventricular systolic dysfunction (1). The pattern of pulsus alternans is detectable by palpation, arterial pressure waveform analysis, and Doppler echocardiography. Competing theories in the early 20^th century attempted to explain this finding. Wenkebach and Straub, using the Starling relationship, suggested that the alternating force of the pulse is due to alternating filling volumes: greater diastolic volumes accommodated by increased fiber length caused forceful contraction/greater stroke volume with subsequently reduced end systolic and therefore end diastolic volumes for the next (weaker) beat; the consequently reduced force left again greater end systolic and end diastolic volumes for the next (more powerful) beat thereafter. Gaskell, Hering, and Wiggers alternatively proposed the phenomenon was rooted in myocardial contractility fluctuations independent of volumes. Laboratory and animal data supported both theories, but seminal clinical work in the 1960s using concurrent ventriculography and ventricular pressure measurements demonstrated that both mechanisms, in fact, occur in different human subjects (2). The second, Starling-independent mechanism is now thought to be due at least in part to delayed intracellular calcium cycling leading to rhythmic fluctuations in excitation-contraction coupling (3).

Regardless of the underlying physiology, the significance of pulsus alternans as a harbinger of severe ventricular dysfunction and poor prognosis has been recognized and unquestioned since its description. This was unfortunately true in the case of our patient, who developed multiorgan failure despite resuscitative efforts and died three days after admission.

Luke M. Gabe, MD

University of Arizona College of Medicine

Department of Internal Medicine

Division of Pulmonary, Allergy, Critical Care and Sleep Medicine

1501 N. Campbell Ave.

Tucson, AZ USA

References

1. Traube L. Ein fall von pulsus bigeminus nebst bemerkungen tiber die lebershwellungen bei Klappenfehlern und über acute leberatrophic. Ber Klin Wschr. 1872;9:185.
2. Cohn KE, Sandler H, Hancock EW. Mechanisms of pulsus alternans. Circulation. 1967 Sep;36(3):372-80. [CrossRef] [PubMed]
3. Euler DE. Cardiac alternans: mechanisms and pathophysiological significance. Cardiovasc Res. 1999 Jun;42(3):583-90. [CrossRef] [PubMed]

Cite as: Gabe LM. Medical image of the week: pulsus alternans. Southwest J Pulm Crit Care. 2016;13(5):266-7. doi: https://doi.org/10.13175/swjpcc123-16 PDF