Chief Complaint: 68-year-old man who collapsed during exertion. History: Roger C
ID: 86699 • Letter: C
Question
Chief Complaint: 68-year-old man who collapsed during exertion. History: Roger Crockett, a 68-year-old man with a 40-pack-year smoking history and recent complaints of angina (sub-sternal chest pressure) upon exercising, collapsed while mowing his lawn. The paramedics at the scene found him unconscious, not breathing, and without a pulse. CPR was successfully performed and Roger was transported to the hospital. An ECG was suggestive of an anterior wall myocardial infarction, and he was given an intravenous solution of tissue plasminogen activator (TPA). Elevated blood creatine phosphokinase (CPK) levels measured over the next 2 days confirmed the diagnosis. Coronary angiography was performed a week later, revealing the following results: Circumflex artery: 20% blocked Right coronary artery: 15% blocked Left anterior descending artery (LAD): 95% blocked ("Anterior intraventricular artery") Questions: 1. While listening to his heart with a stethoscope, you notice a high-pitched, blowing, systolic murmur, heard best directly under the left nipple. A review of Roger's medical records shows no prior history of a heart murmur. What is causing this new murmur? 2. Is the cause of the murmur in any way related to his heart attack? Explain. 3. While listening to his breathing with a stethoscope, you hear some wheezing and inspiratory rales ("crackling noises"). Explain these findings. 4. A chest X-ray taken two weeks after his collapse shows a markedly enlarged cardiac silhouette and generalized haziness at the bases of the lungs. Why is the heart enlarged? 5. Why are the lungs "hazy" on chest X-ray? Roger is stabilized and ultimately discharged from the hospital. Three months after the heart attack, he comes back to his physician for a checkup. He complains of dyspnea ("shortness of breath") at rest and difficulty breathing while lying down ("orthopnea"). He says he can only sleep when he is propped up by two large pillows. 6. Why is he having these symptoms? 7. What is the general name for Roger's condition? 8. Which term more accurately describes the stress placed upon Roger's heart -- increased pre-load or increased aferload? 9. Why does it help Roger to sleep with pillows under his head? 10. What is creatine phosphokinase (CPK) and why are elevated CPK levels in the blood suggestive of a myocardial infarction (heart attack)? 11. What is tissue plasminogen activator (TPA), what is it used for, and how does it work?
Explanation / Answer
(1) What is causing this new murmur?
Roger might have a regurgitant heart valve. The turbulent blood flow causes vibrations of the heart wall and can be heard as a murmur with a stethoscope. The left nipple is the area where the sounds of mitral (or "bicuspid") valve closure normally are heard and if the mitral valve cusps do not completely close, a systolic murmur will be heard.
(2)Is the cause of the murmur in any way related to his heart attack?
The results of the coronary angiography reveal that the left anterior descending or anterior intraventricular artery is completely blocked. This is the artery which supplies blood to the left ventricular wall and the interventricular septum. A blockage of this artery would cause ischemia and infarction of the left ventricular wall. In this case, the papillary muscles are damaged and so with each ventricular contraction, the mitral valve leaflets flip backwards into the left atrium, causing regurgitation of blood and the new heart murmur.
(3) While listening to his breathing with a stethoscope, you hear some wheezing and inspiratory rales ("crackling noises"). Explain these findings
Roger's smoking history shows an increased risk of developing chronic bronchitis and emphysema (both can alter the breath sounds) heard with a stethoscope. The inflammation and mucus pooling in chronic bronchitis reduces the diameter of the airways, creating more airflow turbulence and the lower-pitched breath sounds associated with large airway obstruction; and emphysema might cause smaller airways to either completely collapse or to rapidly oscillate between a partially open and a closed position. This vibration of the bronchiolar wall can create the high-pitched, musical sound of wheezing, particularly upon exhalation.
(4) A chest X-ray taken two weeks after his collapse shows a markedly enlarged cardiac silhouette and generalized haziness at the bases of the lungs. Why is the heart enlarged?
Inorder to maintain a stable cardiac output during mitral regurgitation, the left ventricle must be filled with more blood during ventricular diastole to account for some of the blood which will always be pumped backwards into the left atrium during ventricular systole. So for maintaining the same stroke volume, the pre-load must be increased on his left ventricle which will increase the diameter of the left ventricle causing eccentric hypertrophy of the left ventricle where, the lengthening of the cardiac muscle cells occurs. This would increase the diameter of the ventricle causing the cardiac silhouette to enlarge on a chest X-ray.
(5) Why are the lungs "hazy" on chest X-ray?
He might have interstitial and pulmonary edema. This fluid is denser than air and appears lighter and the air-filled spaces appear darker on an X-ray. Since there is more fluid that builds up in Roger's lungs, the chest X-ray looks hazy.
(6) Why is he having these symptoms?
Roger is suffering from left-sided congestive heart failure and even though his heart has undergone eccentric left ventricular hypertrophy, it is at a sub-optimal level. So, when Roger lies down to bed at night he assumes a horizontal position and eliminates the effect of gravity, and the rate of venous blood flow returning to the right and left atrium increases. This increases the pre-load placed upon Roger's left ventricle. The pumping ability of the left ventricle is already reduced due to the heart attack; any further increase in pre-load may exacerbate his left-sided congestive heart failure. As a result, fluid begins to collect in the lungs, making it difficult for Roger him to breathe.
(7) What is the general name for Roger's condition?
Left-sided congestive heart failure (fluid filling in the lungs)
(8) Which term more accurately describes the stress placed upon Roger's heart - increased pre-load or increased aferload?
increased pre-load
(9) Why does it help Roger to sleep with pillows under his head?
When Roger's sleeps with a pillow under his head, there is a raises his heart above the majority of his systemic circulation, thus lowering the rate of venous return and relieving the shortness of breath.
(10) What is creatine phosphokinase (CPK) and why are elevated CPK levels in the blood suggestive of a myocardial infarction (heart attack)?
CPK is an enzyme found in cardiac muscle cells. This helps in transfering phosphate groups between ADP and creatine phosphate. In times of energy need, this enzyme removes the phosphate groups from creatine phosphate and attaches them to ADP to form ATP. This ATP is useful as a source of chemical energy for the cell. In times of energy excess, the CPK removes the phosphate groups from ATP molecules and store them on the large creatine phosphate matrix. Under normal conditions, this enzyme is only present inside the cells. A raise in CPK levels in the bloodstream might suggest th break down of cardiac muscle cells which happens only during a myocardial infarction or a heart attack and estimating tthe CPK level is a an efficient way to diagnose heart attack.
(11) What is tissue plasminogen activator (TPA), what is it used for, and how does it work?
The TPA is an enzyme useful for dissolving blood clots. It is useful for treating heart attack victims.
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