Pagana: Mosby’s Manual of Diagnostic and Laboratory Tests

Pagana: Mosby’s Manual of Diagnostic and Laboratory Tests, 6th Edition
Case Studies
The patient was a 48-year-old man admitted to the coronary care unit complaining of substernal
chest pain. During the 4 months preceding admission, he noted chest pain radiating to his neck
and jaw during exercise or emotional upsets. The pain dissipated when he discontinued the
activity or relaxed. The results of his physical examination were essentially normal except for a
systolic murmur heard best at the apex of the precordium and radiating into the left axilla.
Studies Results
Routine laboratory work Within normal limits (WNL)
Cardiac enzyme studies
Creatine phosphokinase
(CPK), p. 167
235 units/L (normal: 55–170 units/L)
CPK-MB, p. 171 12 ng/mL (normal: 0–3 ng/mL)
Lactic dehydrogenase (LDH), p. 293 120 units/L (normal: 90–200 units/L)
Serum aspartate aminotransferase
(AST), p. 107
24 International units/L (normal: 5–40 International
Troponins, p. 451 18 ng/mL
Echocardiography, p. 820 Hypokinetic portion of the lateral left ventricle
Electrocardiography (EKG), p. 485 Evidence of left ventricular hypertrophy
Chest x-ray study, p. 956 WNL
Exercise stress test, p. 481 Positive: pain reproduced, ST segment depression noted
on EKG (normal: negative)
Echocardiography, p. 820 Normal ventricular wall motion
Transesophageal echocardiography
(TEE), p. 840
Mitral regurgitation, dilated left atrium
Lipoproteins, p. 304
HDL 29 mg/dL (normal: >45 mg/dL)
LDL 189 mg/dL (normal: 60–180 mg/dL)
VLDL 12 mg/dL (normal: 7–32 mg/dL)
Homocysteine, p. 269 16 mol/L
C-reactive protein (CRP), p. 165 22 mg/dL
Cardiac catheterization, p. 950 All WNL except:
Left ventricular systolic
140 mm Hg (normal: 90–140 mm Hg)
Aortic systolic pressure 130 mm Hg (normal: 90–140 mm Hg)
Ventricular-aortic pressure
5 mm Hg (normal: 0)
Left ventricular function
Cardiac output 3.5 L/min (normal: 3–6 L/min)
Case Studies
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End diastolic volume (EDV) 60 mL/m2
(normal: 50–90 mL/m2
End systolic volume (ESV) 22 mL/m2
(normal: 25 mL/m2
Stroke volume (SV) 38 mL/m2
(SV = EDV − ESV)
Ejection fraction 0.63 (normal: 0.67 ± 0.07)
Cineventriculography Mitral regurgitation present, normal muscle function
(normal: normal ventricle)
Analysis of O2 gas content, p. 98 No shunting (normal: no shunting)
Coronary angiography (coronary
cineangiography), p. 950
90% narrowing of left coronary artery (normal: no
Cardiac radionuclear scanning, p.
Scans normal showed localized area of decreased
perfusion and poor muscle function in the myocardium
during exercise
Cholesterol, p. 138 502 mg/dL (normal: <200 mg/dL)
Triglycerides, p. 447 198 mg/dL (normal: 40–150 mg/dL)
Diagnostic Analysis
Cardiac radionuclear scanning, EKG, and studies ruled out the possibility of MI. Troponins and
serial cardiac enzyme indicated cardiac ischemia. Stress testing and a nucleotide scan indicated
that the patient was having exercise-related myocardial ischemia (angina). Echocardiography
indicated that the heart muscle at the site of ischemia was functioning poorly. Transesophageal
echocardiography indicated that the patient had mitral regurgitation. Cardiac catheterization with
cineventriculography demonstrated near-normal ventricular function, and coronary angiography
indicated significant narrowing of the left coronary artery. Mitral regurgitation was also seen.
The patient’s angina was then thought to be caused by the coronary artery disease. Open heart
surgery was performed. The patient’s mitral valve was replaced with a prosthesis, and an
aortocoronary artery bypass graft was performed. Postoperatively, he had a large pericardial
effusion. This diminished his heart function. He underwent pericardiocentesis, and his function
improved. Because his serum lipids study showed type IIa hyperlipidemia, a low-cholesterol diet
and cholesterol-lowering agents were prescribed. The other cardiac risk factors did indicate
increased risk for coronary heart disease. Six months later he was asymptomatic and jogging 3
miles per day.
Critical Thinking Questions
1. Based on the ratio of cholesterol to HDL, what is the patient’s risk for coronary heart
2. If these blood tests were drawn 1 year ago, what treatment would have been indicated?
3. Could surgery have been avoided?

To determine the patient’s risk for coronary heart disease based on the ratio of cholesterol to HDL (high-density lipoprotein), we need the values for both cholesterol and HDL. According to the provided information, the patient’s cholesterol level is 502 mg/dL and HDL level is 29 mg/dL.
To calculate the ratio, we divide the total cholesterol by the HDL level:
Cholesterol/HDL ratio = Total cholesterol (mg/dL) / HDL (mg/dL)

In this case, the ratio would be:
Ratio = 502 mg/dL / 29 mg/dL = 17.31

Based on the ratio of 17.31, the patient’s risk for coronary heart disease would be considered high. A higher ratio indicates an increased risk, as it suggests a higher level of LDL (low-density lipoprotein) cholesterol relative to the protective HDL cholesterol.

If the blood tests were drawn 1 year ago, it is important to consider the specific values of the blood tests at that time. However, based on the information provided in the case study, we can make some general observations.
The patient’s cholesterol level was 502 mg/dL, which is above the recommended level of less than 200 mg/dL. Additionally, the LDL level was 189 mg/dL, exceeding the normal range of 60-180 mg/dL. These results indicate elevated levels of total cholesterol and LDL cholesterol.

If these blood test results were drawn 1 year ago, they would suggest the presence of dyslipidemia, particularly type IIa hyperlipidemia, which is characterized by elevated LDL cholesterol levels. The treatment indicated would likely involve lifestyle modifications such as dietary changes, regular exercise, and possibly the use of cholesterol-lowering medications (statins) to manage the dyslipidemia and reduce the risk of coronary heart disease.

Based on the information provided, surgery was performed to address the patient’s condition, including mitral valve replacement and aortocoronary artery bypass graft. The surgery was indicated due to the presence of coronary artery disease, significant narrowing of the left coronary artery, and mitral regurgitation observed in the diagnostic tests.
Without more information about the severity and extent of the coronary artery disease and mitral regurgitation, it is difficult to determine if surgery could have been avoided. However, considering the patient’s symptoms of angina, poor heart muscle function at the site of ischemia, and the presence of significant narrowing in the left coronary artery, surgical intervention was likely necessary to alleviate the symptoms, improve cardiac function, and reduce the risk of further complications such as myocardial infarction.

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