Tiffany is worried about her newborn son. Ever since she brought Caleb home from the hospital it has been so hard to get him to eat and he seems to be breathing too hard all the time. At his one month check-up, the nurse tells her that Caleb has only gained one pound since he was born and Tiffany breaks into tears.
Dr. Baker checks over Caleb in the exam room, taking extra time feeling and listening to his chest. After the exam Dr. Baker says, “When I listen to Caleb’s heart I hear an extra sound called a murmur. I want to use an echocardiogram and an ECG to get a good picture of all the parts of his heart.”
After a full day of tests, Tiffany meets with Dr. Baker in his office. He explains, “After a careful review of all the information, I have discovered that Caleb has a hole in the heart muscle wall between his right and left ventricles. We call it a ventricular septal defect. That is probably why he has been so irritable and hard to feed. The hole is not very big, but he will still need to have surgery to repair it.” Although the thought of her tiny son having surgery is terrifying, Tiffany is relieved to know why things have been so tough at home.
Short Answer Questions:
1. Caleb has abnormal heart sounds that tipped the doctor off to a problem. a. Name the normal sounds of the heart and indicate what causes these sounds. The two major sounds that are heard in a normal heart beat sound like “lub dub”. The “lub” is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole. The second sound, “dub” or S2, is caused by the closure of aortic and pulmonic valves, marking the end of systole. (STETHOGRAPHICS.COM)
b. In relation to the normal heart sounds, when would you expect to hear the abnormal sound Dr. Baker heard? Explain your answer. When a valve is stenotic or damaged, the abnormal turbulent flow of blood produces a murmur which can be heard during the normally quiet times of systole or diastole. (MED.UCLA.EDU). In relation to the systole and the diastole a murmur can be detected between the quiet times between the two. Normally, a murmur is a blowing, whooshing, or rasping sound heard during a heartbeat. (NIH.GOV)That is what Dr.Baker probably heard when doing the examination.
2. The defect in Caleb’s heart allows blood to mix between the two ventricular chambers. Due to this defect would you expect the blood to move from left-to-right ventricle or right-to-left ventricle during systole? Explain your answer based on blood pressure and resistance in the heart and great vessels. It goes left to right during systole. The difference is normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, and then is pumped into the lungs where it receives oxygen.
Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta. But when an infant has ventricular septal defect it still allows oxygen-rich (red) blood to pass from the left ventricle, through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right ventricle. (ROCHESTER.EDU) but instead when systole occurs the blood gets mixed because of the septum therefore heart needs to pump harder to ensure that enough blood with oxygen reaches the body.
3. When an echocardiogram is performed, the technician color-codes oxygenated blood (red) and deoxygenated blood (blue). a. In a healthy baby, what color would the blood be within the right and left ventricles, respectively? Right ventricle: deoxygenated (blue), Left ventricle: oxygenated (red)
b. In Caleb’s heart, what color would the blood be within the right and left ventricles, respectively? Left ventricle: oxygenated (red). Right ventricle: will have mixed blood so it will be red and blue because the opening between the two ventricles has an effect similar to a connection between the atria: When the more powerful left ventricle beats, it ejects blood into the right ventricle and pulmonary circuit. (A&P book pg. 677)
4. What happens to Caleb’s systemic cardiac output as a result of his ventricular septal defect (VSD)? Explain your answer. Caleb will produce lower cardiac output because a left-to-right shunt at the ventricular level reduces LV output by the amount of the shunt because of this the body’s compensatory mechanisms will increase intravascular volume because of this lowered cardiac output until LV end-diastolic volume is sufficient to pump both a normal cardiac output and the proportionate left-to-right shunt. (AHAJOURNALS.ORG)
5. Based on the location of Caleb’s defect, what part of the conduction system might be at risk for abnormalities? Well since Caleb has a hole in his heart muscle wall these parts of the conduction system might be at risk for abnormalities the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers. (NIH.GOV 2)
A&P book pg. 677