Question

History: Uncle Simon and Aunt Cleo were playing golf last week. On the back nine, Bart told Cleo he felt nauseated and was having unusual pain in his left arm and across his chest. All of a sudden he felt weak and began sweating. Aunt Cleo noted he was pale and short of breath. She was concerned because of Uncle Simon's other medical conditions, hypertension and juvenile-onset diabetes mellitus. She immediately dialed 911 and told Simon to lay down to wait for the ambulance. Simon was rushed to a hospital and examined in the emergency room. The tests indicated he had 4 blocked coronary arteries. He was scheduled for surgery the next day. Based on the patient’s clinical signs and symptoms, answer the following questions.

1. Describe how the heart muscle performs its job of pumping blood. What happens when the cardiac muscle itself does not get enough blood. (1 pt)





2. Use your knowledge of cardiac circulation to explain the flow of blood through the heart. Why would Simon feel so weak and short of breath when having a heart attack? (2 pts)







3. What is the job of the coronary arteries? Why are they so easily blocked? ( 1 pt)








4. One of the first diagnostic tools used at the hospital was an electrocardiogram (ECG), which reflects the electrical activity of the cardiac muscle. We know that the atria contract first, which is represented by the P wave on an ECG, and then, after a brief delay, the ventricles contract, which is represented by the QRS complex on an ECG. A normal ECG is represented below. Given the fact that there are no nerves in the heart stimulating the cardiac muscle cells, how is the timing of heart contraction coordinated? If an ECG shows a long delay between the P wave and the QRS complex, what type of cardiac tissue might have been damaged. Defend your answer. (2 pts)









5. What test(s) do you suppose were run on Simon? What information about his heart health would you obtain from each test? Which test was most likely used to diagnose his blocked arteries? (1 pt)






6. What kind of surgery will Simon have to correct his problem? (1 pt)




7. What risk factors for heart attack are present in this patient ? If you were the nurse or the nutritionist assigned to Simon, what dietary and lifestyle changes might you advise for him? Explain how these changes would affect his risk for another heart attack. (2 pts)

Answer 1

1. The heart consists of the myocardium, i.e., the muscular layer which is responsible for the pumping action of the heart. It consists of muscle cells supplied by Purkinje fibers which carry the electrical impulse. The pumping action of the heart is the result of coupled contraction and relaxation of the myocardium.

When the cardiac muscle does not get enough blood there is reduced oxygen supply to the cardiac muscle cell leading to the pain in the myocardium due to hypoxia termed as angina.

2. Blood enters the heart through the inferior vena cava and superior vena cava and empties the deoxygenated blood into the right atrium of the heart. With the contraction of the right atrium, blood enters the right ventricles through the open tricuspid valve, from here blood is pushed into the lungs through the pulmonary artery. The oxygenated blood enters the left atrium through the pulmonary vein, from where blood flows into the left ventricles. When the ventricles contract, blood is pushed out to the aorta and the blood is transported to all parts of the body.

A heart attack can cause weakness because the heart is at great stress as it tries to pump blood, wherein some part of blood flow is blocked. During the heart attack, the heart tissues may get damaged and cannot pump out the blood that they receive from the lungs. It results in the build-up of pressure in the heart and pushes the fluid into the lung air sacs causing shortness of breath.

3. Coronary arteries supply the blood to the heart (heart is also an organ which needs blood supply for its functioning), providing it with the oxygen and supplements that the heart muscle needs to work.

Coronary arteries are smooth and elastic, lined with a layer of endothelial cells. As a person ages, the coronary artery wall begins to show lines of fat which cause injury to the walls of arteries. Other products such as inflammatory cells, proteins, waste products, and calcium also begin to stick to the vessel wall forming a plaque which blocks the artery inhibiting blood supply to heart muscles. This condition is called coronary artery disease.