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Challenging Cases: What Is Causing These Patients’ Syncope?

  • Authors: Satish R. Raj, MD, MSCI, FHRS, FRCPC
  • CME Released: 3/28/2018; Reviewed and Renewed: 3/28/2019
  • Valid for credit through: 3/28/2020
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Target Audience and Goal Statement

This activity is intended for cardiologists, neurologists, and primary care physicians.

The goal of this activity is to improve the recognition of neurogenic orthostatic hypotension (NOH) and appropriate treatment and follow-up care.

Upon completion of this activity, participants will have increased knowledge regarding the:

  • Symptoms suggestive of NOH
  • Medical conditions associated with NOH
  • Selection of an initial therapy for NOH given the patient’s medical history and current medications
  • Ongoing assessment of efficacy and safety of treatment for NOH


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  • Satish R. Raj, MD, MSCI, FHRS, FRCPC

    Professor of Cardiac Sciences, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada; Adjunct Associate Professor of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States


    Disclosure: Satish R. Raj, MD, MSCI, FHRS, FRCPC, has disclosed the following relevant financial relationships:
    Served as an advisor or consultant for: Abbott Laboratories; Allergan, Inc.; Boston Scientific; GE Healthcare; H. Lundbeck A/S

    Dr Raj does intend to discuss off-label uses of drugs, mechanical devices, biologics, or diagnostics approved by the FDA for use in the United States.

    Dr Raj does not intend to discuss investigational drugs, mechanical devices, biologics, or diagnostics not approved by the FDA for use in the United States.


  • Catherine Friederich Murray, BS

    Scientific Director, Medscape, LLC


    Disclosure: Catherine Friederich Murray, BS has disclosed no relevant financial relationships.

CME Reviewer

  • Amy Bernard, MS, BSN, RN-BC

    Lead Nurse Planner, Medscape, LLC


    Disclosure: Amy Bernard, MS, BSN, RN-BC, has disclosed no relevant financial relationships.

Peer Reviewer

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Challenging Cases: What Is Causing These Patients’ Syncope?

Authors: Satish R. Raj, MD, MSCI, FHRS, FRCPCFaculty and Disclosures

CME Released: 3/28/2018; Reviewed and Renewed: 3/28/2019

Valid for credit through: 3/28/2020


The following cases are modeled on the interactive grand rounds approach. The questions within the activity are designed to test your current knowledge. After each question, you will be able to see whether you answered correctly and read evidence-based information that supports the most appropriate answer choice. The questions are designed to challenge you; you will not be penalized for answering the questions incorrectly. At the end of the activity, there will be a short post-test assessment based on the material presented.


Almost immediately after someone moves to an upright posture, 300 to 800 mL of blood pools in the legs and the splanchnic venous capacitance system.[1] Venous return and ventricular filling decrease, resulting in diminished stroke volume and cardiac output.[1] Baroreceptors found in the arterial walls of the carotid sinus and aortic arch sense the sudden drop in arterial blood pressure (BP), and their firing rate slows.[2] The loss of baroreceptor inhibition causes an increase in efferent sympathetic outflow by autonomic neurons in the medulla, triggering compensatory mechanisms, such as tachycardia and vasoconstriction, to restore normotension.[3] Orthostatic hypotension (OH), sometimes called postural hypotension, occurs when the body cannot compensate for the drop in cardiac output that occurs with standing.[1]

Figure 1. Neurogenic Orthostatic Hypotension.

This content is no longer available.

Reproduced with permission from Freeman R. Neurogenic orthostatic hypotension. N Engl J Med. 2008;358:615-624.[4]

In people 65 years and older, OH has an estimated prevalence of 5% to 30%, although differences in study protocols make the exact prevalence difficult to determine.[5] The risk for OH increases with age and is significantly more common in institutionalized adults (70%) than community-dwelling adults (6%).[1] Syncope, an abrupt transient loss of consciousness and postural tone with spontaneous fast recovery, is sometimes the first indication of OH.[6] It is important to distinguish syncope, which results from inadequate cerebral nutrient flow, from nonsyncopal causes of loss of consciousness. Orthostatic hypotension-related syncope always happens while standing and is often preceded by light-headedness, weakness, blurred vision, or other symptoms.[1]

Neurogenic OH (NOH), a subtype of OH characterized by defective vasoconstriction caused by insufficient release of norepinephrine from sympathetic vasomotor neurons,[1] is more common in people with neurodegenerative disorders or conditions that cause autonomic dysfunction.[7] Although NOH is often asymptomatic, some patients experience syncope or presyncope. Clinicians need to remain aware of NOH, which can cause significant morbidity and mortality.[2,8,9] Clinicians should know whom to screen for NOH, how to screen for NOH, how to educate patients with NOH, and how to manage NOH using evidence-based pharmacologic and nonpharmacologic approaches.

Case 1.

Ellen is a 70-year-old woman with no significant health problems. Over the past 5 weeks, she has experienced 2 episodes of syncope, the first of which occurred while she was walking on a sunny, 95°F day. She suddenly felt lightheaded and then fainted, but she regained consciousness almost immediately. Her husband helped her back to the house, and she felt better after resting. Ellen assumed she had fainted because of the heat and did not seek medical care. The second episode occurred 3 days ago, after dinner at an Italian restaurant. She felt fine until she exited the car at home, at which point she again became lightheaded and lost consciousness for a few seconds. The next day, Ellen saw her primary care provider about her "fainting spells." Her BP was 135/80 mm Hg and heart rate was 70 bpm. Ellen mentioned she often felt lightheaded when standing or after exercise and sometimes had palpitations, which prompted her primary care provider to refer her to a cardiologist.

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