A Case Study on Valve Function_NicoleLinebaugh
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Feb 20, 2024
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A&P 2
Name & N#: ______Nicole Linebaugh
N01572555_____________________________________
A Case Study on Valve Function
Carl arrived at the ER suffering from severe shortness of breath (dyspnea) that began approximately 12 hours earlier. He was an active 64-year-old, with no recent illness or shortness of breath before today. He had a prior history of appendicitis, but was otherwise healthy, with no known cardiovascular issues or other chronic medical conditions. A chest X-ray showed some opacity of both lungs, but his heart was not enlarged. Additional tests ruled out a myocardial
infarction, but the doctor detected a noticeable murmur when listening to Carl’s heart. Carl was surprised to hear this, and reported that he had never been diagnosed with a heart murmur even though he had had regular physicals for the past 30 years. An echocardiogram (an ultrasound of the heart) showed that several of the chordae tendineae connected to the anterior leaflet of the left atrioventricular valve had ruptured. Use the following data to answer the questions below.
Heart rate: 102 bpm
End diastolic volume (EDV): 115 ml (within normal range)
End systolic volume (ESV): 30 ml (decreased)
Left ventricle size: normal
Left atrial size: normal Short Answer Questions
. Type or write your answers in the spaces below, changing the font for easier grading. Cite your sources.
1.
Explain how the ruptured chordae tendineae are related to the newly-detected murmur. The role of the chordae tendinae is to impede the passage of atrioventricular valves into the atria. If there is a tear in one of the chordae tendinae connected to the anterior leaflet of the left atrioventricular valve, it can result in blood regurgitating back into the atrium and an insufficient closure of the valve. This not only disrupts the normal and efficient circulation of blood but also causes a characteristic sound known as a murmur (Chapter 19.3 McGraw Hill Textbook). 2.
Consider the path blood now takes during contraction of Carl’s left ventricle and the influence of afterload. Why is his ESV less than normal? In a healthy heart, the left ventricle pumps oxygenated blood into the aorta. The opening of the aortic valve allows for the flow of blood from the left ventricle into the aorta, which is then distributed throughout the body. The concept of afterload refers to the resistance that the left ventricle must overcome in order to eject blood into the aorta. It represents the amount of effort required for the heart to expel blood. Due to Carl's ruptured chordae tendineae, his End-Systolic Volume is reduced as the left ventricle may not be able to fully empty during contraction. Consequently, there will be a decrease in both blood volume and work exerted by the left ventricle at the end of systole when compared to a healthy heart. (Chapter 19.7 McGraw Hill Textbook).
A&P 2
Name & N#: ______Nicole Linebaugh
N01572555_____________________________________
3.
Why is Carl’s heart rate elevated? Carl's elevated heart rate may be a result of the reverse flow of blood he is experiencing. In his case of a ruptured chordae tendineae, some of the blood that was supposed to be pumped by the left ventricle flows back into the left atrium. As a consequence, there is a decrease in the amount of blood ejected into the systemic circulation. To maintain an adequate cardiac output, it is likely that Carl's heart compensated by increasing its rate of beating (National Center for Biotechnology Information).
4.
Without treatment, this condition will result in enlargement of Carl’s left ventricle. Why is this the case, and what consequence(s) would this have on his cardiovascular health?
In Carl's situation, it is probable to observe an enlargement of the left ventricle due to a ruptured chordae tendinea. This can be attributed to a malfunctioning mitral (bicuspid) valve and the resulting backflow of blood. As the left ventricle contracts, there is likely a slight backward flow of blood into the left atrium because of the incomplete or ineffective closure of the valve. Consequently, this leads to a volume overload on the left ventricle. The heart has to exert more effort in managing this backflow into the left atrium, which requires the left ventricle to generate higher pressures for pushing out this additional blood through the aorta. All these factors contribute to explaining why Carl's left ventricle has become enlarged. (Chapter 19.9 McGraw Hill Textbook).
5.
Tests ruled out a myocardial infarction for Carl. What is a myocardial infarction? What type of test could determine if this is what he was experiencing?
A heart attack, also known as a myocardial infarction, occurs when the cardiac muscle begins to die off due to insufficient blood flow and lack of oxygen for more than a few minutes. This deficiency in oxygen supply is caused by inadequate delivery through the coronary circulation. To diagnose a heart attack, medical professionals can employ electrocardiograms (ECG/EKG) and blood tests. An ECG records the combined electrical activity of pacemaker cells and contractile cells, observed as electrical waves. (Chapter 19.5 McGraw Hill Textbook).
Reference:
Burton LV, Beier K. Papillary Muscle Rupture. [Updated 2023 May 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499976/
Anatomy & Physiology, 4e. O’Laughlin, Bidle, & McKinley. Chapter 19 Pg. 745-771.
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