Case Presentation
Allison Jacobson is a 19-year-old sophomore majoring in pre-medicine at the
University of Arizona. In the past few weeks leading up to final exams, Allison
has felt unusually tired despite receiving an adequate amount of sleep at night.
She also has had frequent headaches, and has experienced times when her heart
“felt like it was missing a beat.” Yesterday at lunch, Allison fainted while waiting
in line in the cafeteria. Initially, she attributed this episode to being unusually
tired and hungry, but later in the day she fainted again while waiting to mail a
package at the Post Office.
When Allison informed her mother about what had happened that day, her
mother immediately scheduled an appointment for Allison to see the family
physician. Though no abnormalities where found when he examined Allison, her
physician ordered a battery of diagnostic tests, including a head-up tilt (hut) test.
Questions
1. Define the following terms as they relate to cardiodynamics: stroke volume, end systolic volume, and
end diastolic volume. De?ne the following terms and state how each relates to systemic arterial
blood pressure: cardiac output and total peripheral resistance.
2. Explain the following: the Frank-Starling law of the heart, the control of cardiac activity by the
autonomic nervous system, and the baroreceptor re? ex in the maintenance of systemic blood
pressure.
3. Define the term dysautonomia, and brie? y describe the condition known as neurocardiogenic
syncope (ncs).
4. What are the symptoms of ncs?
5. What is the mechanism by which ncs occurs?
6. Discuss how ncs is diagnosed and treated.