Assignment 7

1 .		Foxglove is often used for the treatment of patients with a cardiovascular disorder known as congestive heart failure. You will simulate the use of foxglove on patients with congestive heart failure in the next assignment. The following question is designed to help you examine the effects of foxglove. Working within CardioLab and referring to the detailed instructions on Assignment 7, answer the question below. Click on the Start button to monitor cardiovascular parameters in a normal human. Allow this to proceed for a few seconds, then in the Interventions view, select Foxglove from the popup menu and click on the Apply Intervention button once. What happens to heart rate and blood pressure after you give foxglove? What happens to total peripheral resistance? Explain your results below.
2 .		It has been estimated that over 8 million people in the United States and Europe suffer from congestive heart failure. This condition is a progressive disorder characterized by a decrease in cardiac output, and consequently blood flow, due to a number of different problems. In many patients with CHF, the problem is due to an enlarged left ventricle that is weak and ineffective at adequately pumping blood into the cardiovascular system. In other patients, damage to muscle cells in the walls of the left ventricle prevent the ventricle from maintaining normal cardiac output. In either case, because the left ventricle is unable to pump with the same effectiveness as the right ventricle, blood backs up into the pulmonary circuit, creating "congestion." In the Cases view, start an experiment to follow normal heart rates. After a few seconds, stop the normal run by clicking the Stop button. Simulate CHF by selecting Congestive Heart Failure from the popup menu and then clicking on the Apply Case button. To begin the simulation, click the Start button. Observe what happens to each of the cardiovascular parameters in a CHF patient. Follow this patient for several seconds until you have a clear picture of which cardiovascular parameters may be changing. Describe the symptoms that this patient is experiencing. Do they make sense to you based on what you know about CHF? Why or why not?
3 .		Simulate the foxglove treatment for CHF by returning to the Interventions view. Select Foxglove from the popup menu, then click on the Apply Intervention button. What effect does foxglove have on cardiovascular parameters in the CHF patient? Carefully study any changes in cardiovascular parameters and describe what these changes are.
4 .		Simulate hypertension by selecting Hypertension from the popup menu and then clicking on the Apply Case button. Observe what happens to each of the cardiovascular parameters in a hypertensive patient. Follow this patient for several seconds until you have a clear picture of which cardiovascular parameters may be changing. Think about which parameters you might want to manipulate to help this patient. Because many of the drugs that are used to treat hypertension affect heart rate and blood vessel diameter, see if you can use the Variables feature to lower blood pressure in this patient.
5 .		Discuss desirable effects that will lower blood pressure in hypertensive patients.
6 .		Simulate stenosis by selecting Mitral Valve Stenosis from the popup menu and then clicking on the Apply Case button. Observe what happens to each of the cardiovascular parameters in this patient. Follow this patient for several seconds until you have a clear picture of which cardiovascular parameters may be changing. What happens to blood pressure in this patient? Based on what you know about the neural control of heart rate, discuss what is happening to heart rate and explain why this is occurring.