Sofia Martinez is a 19-year-old sophomore majoring in pre-medicine at the Univer
ID: 258856 • Letter: S
Question
Sofia Martinez 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.” She has noticed lightheadness and blurred vision at times. Friends sometimes comment that she looks “pale and tired”. Yesterday at lunch, Sofia 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. Both times she collapsed to the floor but recovered spontaneously.
When Sofia informed her mother about what had happened that day, her mother immediately scheduled an appointment for Sofia to see the family physician.
1. List the common causes of fainting as pertains to Sofia’s situation and a short explanation of each.
A battery of tests were performed including:
Blood Sugar after fasting normal
Heme test normal
Hemoglobin normal
Respiration normal
Blood pressure normal
Abd/Pelvic ultrasound normal
Aortic ultrasound normal
2. Why were these tests performed? What would an abnormal result indicate?
3. Define the following terms as they relate to cardiodynamics:
a. Heart rate
b. EDV
c. ESV
d. Stroke Volume
4. Explain the Frank-Starling law of the heart? What is the relationship between HR and SV?
5. Explain the control of cardiac activity by the ANS. Describe the mechanism of altering depolarization rate of the SA node. Which neurotransmitters and hormones are involved? How does the ANS alter contractility?
6. What is the baroreceptor reflex? How is it involved in the maintenance of systemic blood pressure? Where are the baroreceptors located? How do they function?
An ECG was performed.
7. Describe the method of obtaining an ECG. Find and attach a normal ECG. Label the waves and intervals. List each wave and what is happening in the heart when they occur. What other things can be determined from an ECG?
Her physician then ordered a two part tilt-table test: first with no drug additive; second with isoproterenol.
The nurse strapped Sofia to the table and inserted an IV line. She also hooked Sofia up to an ECG machine and used a BP cuff on her arm. The table was then tilted to about 30 degrees for about 5 minutes. Afterwards the table was tilted to approximately 70 degrees and Sofia was left in that position for 50 minutes. BP and ECG were constantly monitored.
8. What is a “table-tilt” test used for? Why are BP and ECG constantly monitored?
The second part of the test was performed later that day. Sofia was again strapped to the table and the BP cuff and ECG were attached. The IV was reinserted. Isoproterenol was injected through the ECG tube in successive dosages of 0, 2 and 5 micrograms/min.
9. What is isoproterenol and what is it used for? How does it work?
The results of Sofia’s test were as follows:
0 mcg/min
No change after 10 mins
HR 117 bpm
Systolic BP 118 mm Hg
2 mcg/min
No change after 10 mins
HR 118
Systolic BP 120 mm Hg
5 mcg/min
Within 2 mins Sofia’s HR and BP dropped significantly
HR 67
Systolic BP 66 mm Hg
Sofia was quickly lowered to a reclining position
After 3 mins
HR 122
Systolic BP 121 mm Hg
10. What is the equation for blood pressure? How does each factor affect BP? What does body position have to do with BP? Discuss venous return and EDV and their effects on BP.
11. What is your diagnosis of Sofia’s condition? Discuss the mechanism of what is happening with Sofia? Why did it Sofia’s HR and BP decrease in an upright position but returned to normal in the reclining position?
12. Is there a “cure” for Sofia’s condition? Determine a treatment plan for Sofia? What lifestyle changes would you suggest she make?
Explanation / Answer
1. List the common causes of fainting as pertains to Sofia’s situation and a short explanation of each.
Common causes of fainting are hunger, low blood pressure, tiredness. One of the most reasons of fainting in the case of Sofia may be heart arrhythmia. The symptoms may be dizziness, light headedness, slow heart rate or breath shortness of pain in the chest.
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