Cardiovascular short Essay Assignment

Cardiovascular short Essay Assignment

PART A

In the lab, you simulated blood flow from a beating heart into blood vessels. You varied the radius and length of the vessels and the viscosity of the blood. Your experiments are summarized in the tables below.

Table 1. Results from study A

  Vessel radius (mm) Blood viscosity (n.u.) Vessel length (mm)
Experiment 1 2.4 3.2 10
Experiment 2 1.3 5.7 40
Experiment 3 2.4 5.7 10
Experiment 4 1.3 3.2 40
Experiment 5 2.4 5.7 40

Abbreviations: n.u. = no units

Table 2. Results from study B

  Vessel radius (mm) Blood viscosity (n.u.) Vessel length (mm)
Experiment 6 5.0 6.4 34
Experiment 7 2.5 6.4 34
Experiment 8 2.5 6.4 17
Experiment 9 2.5 3.2 34

Abbreviations: n.u. = no units

FOR THE FOLLOWING QUESTIONS, JUSTIFY ALL ANSWERS USING THE NUMBERS PROVIDED.

Question 1: In which of the experiments from Study A (Table 1) do you expect the resistance to be the highest? The lowest? Explain your answer. Assume that pressure remains constant in all these experiments.

Question 2: In which of the experiments from Study A (Table 1) do you expect the blood flow to be the highest? The lowest? Explain your answer. Assume that pressure remains constant in all these experiments.

Question 3: In Study B (Table 2), which of the experiments do you expect will have the greatest blood flow? Explain your answer. Assume that pressure remains constant.

Question 4: In Study B (Table 2), let’s assume that the blood flow for experiment 7 is 50 mL/min. Calculate the blood flow for experiment 6. Show your calculations. Assume that pressure remains constant.

PART B

This is the last day of your placement as a nurse in the cardiology ward of the local hospital. As a “going away present”, your supervisor presents you and your colleagues with 6 case-studies related to cardiovascular physiology. She wants to discuss these with you later today. Make sure you are ready to impress her by going through the questions below.

 

Table 3. Cardiovascular parameters for the 6 case-study patients.

  Heart rate (bpm) Stroke volume (mL) Cardiac output (L/min)3 Ejection fraction (%)
P 162 110 A 75
B 60 B 4.20 60
A 65 64 4.16 48
H 382 76 2.89 58
F 78 43 3.35 35
D F 62 6.82 62

 

  Total peripheral resistance1(mm Hg・min・L-1) Blood pressure (mm Hg) Mean arterial pressure (mm Hg) Main complaint(s)
P 5.99 146/87 106.7 None
B 22.22 118/81 93.3 None
A C 178/86 116.7 Mild chest pain
H Not relevant 110/65 D Heart palpitations
F Not relevant E/54 64.7 Chest pain, shortness of breath, fatigue
D Not relevant 134/76 95.3 Heart palpitations

1 Remember that total peripheral resistance (TPR) is determined by the length of blood vessels, viscosity of blood, and radius of blood vessels. Among these 3 factors, vessels length and blood viscosity stay generally constant between patients. Therefore, a change in TPR should be interpreted as a change in vessel radius.

This is an average value, but the heart rate was unstable (i.e. heart rate was increasing and decreasing erratically).

3 Notice the different units: stroke volume is expressed in milliliters (mL) while cardiac output is expressed in liters per minute (L/min).

Normal Values for Cardiovascular Parameters

Resting heart rate (bpm): ∼70 (range: 60-80)

Stroke volume (mL): ∼70 (range: 60-100)

Cardiac output (L/min): ∼5.0 (range: 4.0-8.0)

Ejection fraction (%): between 50-70%

Systolic blood pressure (mm Hg): ∼120 (range: 90-140)

Diastolic blood pressure (mm Hg): ∼80 (range: 60-90)

Mean arterial pressure (mm Hg): ∼93 (range: 70-105)

Total peripheral resistance: normal range not available

 

FOR THE FOLLOWING QUESTIONS, JUSTIFY ALL ANSWERS.

Question 5: Cardiovascular parameters such as heart rate, stroke volume, cardiac output, blood pressure, and mean arterial pressure are all linked, mathematically and physiologically. First, calculate the 6 missing parameters identified by red letters (A-F) in the chart above. Show all your calculations.

Question 6: For each of the 6 patients above, list all of the parameters that are out of normal range and indicate whether they are higher or lower than normal.

Question 7: Based on the observations made above, match each of the patients above with one of the following “diagnosis”: healthy patient at rest, atherosclerosis, early hyperkalemia, tachycardia, healthy patient doing high-intensity exercise, left heart failure. Explain your reasoning.

Question 8: Which patient would most benefit from using a beta-blocker drug? Explain how this drug works and why it would help this specific patient.

  • Make sure to include the effects of the drug on both heart rate and force of cardiac contractions.
  • Make sure to identify the receptor beta-blockers targets and whether they activate or inhibit it.

Question 9: Which patient would most benefit from using the drug atropine (see PhysioEx exercise 6, activity 4)? Explain how this drug works and why it would help this specific patient.

  • Make sure to include the effects of the drug on heart rate.
  • Make sure to identify the receptor atropine targets and whether it activates or inhibits it.