Lab

1. Common Laboratory & Imaging
studies in CV patients & their
Interpretation
Wossen Teferra, M.D. Cardiology Fellow

2. • The clinical examination remains the basis for the diagnosis of a wide
variety of cardiac disorders
• laboratory tests & Imaging studies are used to supplement the clinical
examination

3. CBC
• Hematocrit/hemoglobin levels aid in the assessment of severe
anemia, which may cause or aggravate heart failure.
• Leukocytosis may signal underlying infection

4. Serum electrolyte
• Hyponatremia (low sodium level): In cases of severe heart failure, sodium
restriction, diuretic therapy and the inability to excrete water, may lead to
hyponatremia.
Dilutional hyponatremia occurs because of a substantial expansion of
extracellular and intravascular fluid volume and a normal or increased level
of total body sodium.
• Hypokalemia (low potassium level): may result incase of prolonged
administration of diuretics may result in hypokalemia.
• Hyperkalemia may occur in patients with severe heart failure who show
marked reductions in glomerular filtration rate (GFR) particularly if they
are receiving potassium-sparing diuretics and/or angiotensin-converting
enzyme inhibitors (ACEIs).
• Calcium and magnesium levels may decrease due to the use of diuretics &
may cause arrhythmia

5. Renal function tests
• Patients with severe heart failure, particularly those on large doses
of diuretics for long periods, may have elevated Blood urea nitrogen
(BUN) and creatinine levels indicative of renal insufficiency owing to
chronic reductions of renal blood flow from reduced cardiac output.

6. Liver function tests
• Congestive hepatomegaly and cardiac cirrhosis are associated with
impaired hepatic function, is characterized by raised values of aspartate
aminotransferase (AST), alanine aminotransferase (ALT), alkaline
phosphatase (ALP) Hyperbilirubinemia secondary to an increase in the
direct and indirectly bilirubin & prolonged prothrombin time (PT).
• In patients with long-standing heart failure, albumin synthesis may be
impaired, leading to hypoalbuminemia and intensifying the accumulation
of fluid.
• the impairment of hepatic function rapidly resolves by successful
treatment of heart failure.

7. Natriuretic peptides (BNP & NT-proBNP
• B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP),
are released from the failing heart,
• They are relatively sensitive markers for the presence of Heart Failure,
& are useful tools in the diagnosis of patients with Heart Failure especially
in the presence of clinical uncertainity
• the measurement of BNP or NT-proBNP is useful for establishing
prognosis or disease severity in chronic HF
• natriuretic peptide levels increase with age and renal impairment, are
more elevated in women, BNP levels may increase in patients taking
drugs like angiotensin receptor blocker neprilysin inhibitors
• Levels can be falsely low in obese patients.

8. Cardiac Troponins
• Elevated Cardiac troponins I or T are used to diagnose acute coronary
syndrome, may also indicate cardiac ischemia and myocyte damage
related to HF

9. D-dimer
• D-dimer is the degradation product of crosslinked fibrin
• Elevated plasma D-dimer levels indicate that coagulation has been
activated, fibrin clot has formed, and clot degradation by plasmin has
occurred
• There are many causes of elevated D-dimer; identification of the
underlying cause requires correlation with the clinical picture and
other laboratory results
• provide clinical utility in the evaluation of pulmonary embolism.
• Low levels make the diagnosis of pulmonary embolism unlikely

10. PT/INR
• used in the monitoring of patients taking vitamin K
antagonists (warfarin) which are taken for the prevention &
treatment of thrombotic & embolic events.

11. Lab tests done in patients at risk or with estabilished Atherosclerotic
Cardiovascular Disease (ASCVD)
• Fasting blood sugar & HBA1C : to diagnose Diabetes
• Lipid Profile: Total cholesterol, Low density Lipoproteins (LDL), High
Density Lipoprotiens (HDL), Triglycerides are used to diagnose
dyslipedemias
• Urinalysis: Increased albuminuria is recognized as an independent
risk factor for cardiovascular disease; it should be performed in all
patients with diabetes or chronic kidney disease
• CRP: elevated levels are risk factors for atherosclerosis

12. Thyroid Function tests (TSH, T4, T3)
• To diagnose thyroid disorders which may cause cardiac illnesses
• Hyperthyroidism may cause Atrial fibrillation, rate related
cardiomyopathy & pulmonary hypertension
• Hypothyroidism may cause heart blocks resulting in bradycardia

13. • Blood cultures: used to make the diagnosis of Infective endocarditis,
or systemic infection
• Serology for HIV: can be tested to diagnose HIV associated
cardiomyopathy

14. Imaging tests
Chest X-Ray
• A chest x-ray provides useful information about cardiac size and
shape, as well as the state of the pulmonary vasculature, and may
identify noncardiac causes of the patient’s symptoms.
• Although patients with acute HF have evidence of pulmonary
hypertension, interstitial edema, and/or pulmonary edema, the
majority of patients with chronic HF do not.

15. ECG or EKG
• is a graphic representation of electrical activity generated by the
heart.
• The signals, detected by means of metal electrodes attached to the
extremities and chest wall, are amplified and recorded by the
electrocardiograph.
• It is used to detect
arrhythmia
myocardial ischemia & infarctions,
RV/LV hypertrophy,
electrolyte disturbances
acute pericardits

16. Echocardiography
• uses ultrasound to penetrate the body, reflect from relevant
structures, and generate an image.
• hardware and software are optimized for evaluation of cardiac
structure and function.
• can be used to interrogate blood flow within the heart and blood
vessels by using the Doppler principle to ascertain the velocity of
blood flow.

17. Renal Function Monitoring
• Serum electrolyte and renal function tests are recommended for serial
monitoring in HF, both in the acute and chronic settings,
because worsening renal function is associated with a poor prognosis. 2
• The frequency of renal function monitoring depends on the clinical status
of the patient.1
• 4
• Serum electrolytes and renal function tests are also recommended in
patients on angiotensin-converting enzyme inhibitors, angiotensin II
receptor blockers, and diuretics.4
• 5

18. • Measurement of BNP or NT-proBNP is useful for establishing disease
severity and prognosis in chronic HF 2
• 3
• and for prognosis in the acute setting. 2
• 3
• Cardiac troponins may add additional prognostic value. 3

19. • Cardiac-specific troponin T (cTnT) and cardiac-specific troponin I (cTnI)
have amino-acid sequences different from those of the skeletal
muscle forms of these proteins.
• These differences permitted the development of quantitative assays
for cTnT and cTnI with highly specific monoclonal antibodies. cTnT and
cTnI may increase after STEMI to levels many times higher than the
upper reference limit (the highest value seen in 99% of a reference
population not suffering from MI), the measurement of cTnT or cTnI is
of considerable diagnostic usefulness, and they are now the preferred
biochemical markers for MI (Fig. 269-3).
• With improvements in the assays for the cardiac-specific troponins, it
is now possible to detect concentrations

20. • <1 ng/L in patients without ischemic-type chest discomfort.
• The cardiac troponins are particularly valuable when there is clinical
suspicion of either skeletal muscle injury or a small MI that may be
below the detection limit for creatine phosphokinase (CK) and its MB
isoenzyme (CK-MB) measurements, and they are, therefore, of
particular value in distinguishing UA from NSTEMI. In practical terms,
the high-sensitivity troponin assays are of less immediate value in
patients with STEMI. Contemporary urgent reperfusion strategies
necessitate making a decision (based largely on a combination of
clinical and ECG findings) before the results of blood tests have
returned from the laboratory.
• Levels of cTnI and cTnT may remain elevated for 7–10 days after
STEMI.

21. • CK rises within 4–8 h and generally returns to normal by 48–72 h (Fig. 269-
3). An important drawback of total CK measurement is its lack of specificity
for STEMI, as CK may be elevated with skeletal muscle disease or trauma,
including intramuscular injection.
• The MB isoenzyme of CK has the advantage over total CK that it is not
present in significant concentrations in extracardiac tissue and, therefore,
is considerably more specific. However, cardiac surgery, myocarditis, and
electrical cardioversion often result in elevated serum levels of the MB
isoenzyme. A ratio (relative index) of CK-MB mass to CK activity ≥2.5
suggests but is not diagnostic of a myocardial rather than a skeletal muscle
source for the CK-MB elevation.
• Many hospitals are using cTnT or cTnI rather than CK-MB as the routine
serum cardiac marker for diagnosis of STEMI, although any of these
analytes remains clinically acceptable. It is not cost-effective to measure
both a cardiac-specific troponin and CK-MB at all time points in every
patient.

22. Biomarkers
• Circulating levels of natriuretic peptides are useful and important adjunctive
tools in the diagnosis of patients with HF.
• Both B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP),
which are released from the failing heart, are relatively sensitive markers for the
presence of HF with depressed EF; they also are elevated in HF patients with a
preserved EF, albeit to a lesser degree.
• In ambulatory patients with dyspnea, the measurement of BNP or NT-proBNP is
useful to support clinical decision-making regarding the diagnosis of HF, especially
in the setting of clinical uncertainty.
• Moreover, the measurement of BNP or NT-proBNP is useful for establishing
prognosis or disease severity in chronic HF and can be useful to achieve optimal
dosing of medical therapy in select clinically euvolemic patients.
• However, it is important to recognize that natriuretic peptide levels increase with
age and renal impairment, are more elevated in women, and can be elevated in
right HF from any cause. BNP levels may increase in patients taking ARNIs.
• Levels can be falsely low in obese patients. Other biomarkers, such as soluble ST-
2 and galectin-3, are newer biomarkers that can be used for determining the
prognosis of HF patients

23. • The clinical examination remains the basis for the diagnosis of a wide variety of
disorders.
• The clinical examination may then be supplemented by five types of laboratory
tests:
(1) ECG
(2) noninvasive imaging examinations ( Chest X-ray, Echocardiogram, radionuclide
imaging, computed tomographic imaging, positron emission tomography, and
magnetic resonance imaging)
(3) blood tests to assess risk (e.g., lipid determinations, C-reactive protein) or
cardiac function (e.g., brain natriuretic peptide [BNP] [Chap. 252]),
(4) occasionally specialized invasive examinations (i.e., cardiac catheterization and
coronary arteriography
(5) genetic tests to identify monogenic cardiac diseases (e.g., hypertrophic
cardiomyopathy [Chap. 254], Marfan’s syndrome [Chap. 406], and abnormalities of
cardiac ion channels that lead to prolongation of the QT interval and an increase in
the risk of sudden death [Chap. 241]).

24. • Echocardiography uses high-frequency sound waves (ultrasound) to
penetrate the body, reflect from relevant structures, and generate an
image.
• hardware and software are optimized for evaluation of cardiac
structure and function.
• provide information about cardiac structure and function,
• can be used to interrogate blood flow within the heart and blood
vessels by using the Doppler principle to ascertain the velocity of
blood flow.

25. RADIONUCLIDE IMAGING
• Radionuclide imaging techniques are commonly used for the evaluation of
patients with known or suspected coronary artery disease (CAD),
including for initial diagnosis and risk stratification as well as the
assessment of myocardial viability.
• These techniques use small amounts of radiopharmaceuticals (Table 236-
1), which are injected intravenously and trapped in the heart and/or
vascular cells.
• Radioactivity within the heart and vasculature decays by emitting gamma
rays.
• The interaction between these gamma rays and the detectors in specialized
scanners (single-photon emission computed tomography [SPECT] and PET)
creates a scintillation event or light output, which can be captured by
digital recording equipment to form an image of the heart and vasculature.

27. Cardiac magnetic resonance (CMR) imaging
• is based on imaging of protons in hydrogen, which is an advantage, given
the abundance of water in the human body. When the body is placed
inside a MRI scanner, protons in different tissues, such as in simple fluid or
complex macromolecules such as fat or protein, interact with the magnetic
field at their unique frequencies. A set of orthogonal gradient coils in the
scanner is designed to locate protons spatially so that radiofrequency (RF)
pulses of energy can be delivered to select imaging planes of interests.
Once the RF pulses stop, the energy absorbed will be released, collected by
the phased-array receiver coils placed on the patient’s body surface,
digitally recorded in a data matrix known as the K-space, then
reconstructed into a magnetic resonance image. The large arrays of
software methods of delivering RF pulses are known as pulse sequences
which aim at extraction of different types of cardiac structural or
physiologic information

28. CARDIAC COMPUTED TOMOGRAPHY
• CT acquires images by passing a thin x-ray beam through the body at
many angles to generate cross-sectional images.
• The x-ray transmission measurements are collected by a detector
array and digitized into pixels that form an image.
• The grayscale information in individual pixels is determined by the
attenuation of the x-ray beam along its path by tissues of different
densities, referenced to the value for water
• Cardiac CT produces tomographic images of the heart and
surrounding structures.

29. • Routine Laboratory Testing Patients with new-onset HF and those
with chronic HF and acute decompensation should have a complete
blood count, a panel of electrolytes, blood urea nitrogen, serum
creatinine, hepatic enzymes, and a urinalysis. Selected patients
should have assessment for diabetes mellitus (fasting serum glucose
or oral glucose tolerance test), dyslipidemia (fasting lipid panel), and
thyroid abnormalities (thyroid-stimulating hormone level).

30. Modern cardiovascular imaging consists of
• echocardiography (cardiac ultrasound),
• nuclear scintigraphy including positron emission tomography (PET)
imaging,
• magnetic resonance imaging (MRI), and
• computed tomography (CT)

31. lipid panel or lipid profile
• , measures the fats in the blood.
• The measurements can help determine the risk of having a heart
attack or other heart disease. The test typically includes
measurements of:
• Total cholesterol. This is the amount of the blood's cholesterol
content. A high level can increase the risk of heart disease.
• Ideally, the total cholesterol level should be below 200 milligrams per
deciliter (mg/dL) or 5.2 millimoles per liter (mmol/L).

32. Low-density lipoprotein (LDL) cholesterol.
• Excess LDL cholesterol in the blood causes plaque to buildup in the arteries, which
reduces blood flow.
• These plaque deposits may rupture and lead to major heart and blood vessel problems.
• The LDL cholesterol level should be less than 130 mg/dL.
• Desirable levels are < 70 mg/dL : especially if you have diabetes or a history of heart
attack, a heart stent, heart bypass surgery, or other heart or vascular condition.
High-density lipoprotein (HDL) cholesterol.
• Men should aim for an HDL cholesterol level over 40 mg/dL (1.0 mmol/L). Women should
aim for an HDL over 50 mg/dL (1.3 mmol/L).
Triglycerides. Triglycerides are another type of fat in the blood. High triglyceride levels
usually mean you regularly eat more calories than you burn. High levels can increase the
risk of heart disease.
• The recommended triglyceride level is less than 150 mg/dL (1.7 mmol/L).
Non-HDL cholesterol. Non-high density lipoprotein cholesterol (non-HDL-C) is the
difference between total cholesterol and HDL cholesterol. Non-HDL-C includes cholesterol
in lipoprotein particles that are involved in hardening of the arteries. Non-HDL-C fraction
may be a better marker of risk than total cholesterol or LDL cholesterol.

33. • Routine Laboratory Testing Patients with new-onset HF and those
with chronic HF and acute decompensation should have a complete
blood count, a panel of electrolytes, blood urea nitrogen, serum
creatinine, hepatic enzymes, and a urinalysis.
• Selected patients should have assessment for diabetes mellitus
(fasting serum glucose or oral glucose tolerance test), dyslipidemia
(fasting lipid panel), and thyroid abnormalities (thyroid-stimulating
hormone level).

34. • The urine should be examined for evidence of diabetes mellitus and renal
disease (including microalbuminuria) since these conditions accelerate
atherosclerosis.
• measurements of lipids (cholesterol—total, LDL, HDL—and triglycerides),
• glucose (hemoglobin A1C),
• creatinine,
• hematocrit,
• thyroid function
• Evidence exists that an elevated level of high-sensitivity C-reactive protein
(CRP) (specifically, between 0 and 3 mg/dL) is an independent risk factor
for IHD and may be useful in therapeutic decision-making about the
initiation of hypolipidemic treatment. The major benefit of high-sensitivity
CRP is in reclassifying the risk of IHD in patients in the “intermediate” risk
category on the basis of traditional risk factors.

35. ECG or EKG
• is a graphic representation of electrical activity generated by the
heart.
• The signals, detected by means of metal electrodes attached to the
extremities and chest wall, are amplified and recorded by the
electrocardiograph.
• It is used to detect arrhythmias and myocardial ischemia, it may
reveal findings related to life-threatening metabolic disturbances or
to increased susceptibility to sudden cardiac arrest
• A routine 12-lead ECG is used to assess cardiac rhythm and determine
the presence of LV hypertrophy or a prior MI (presence or absence of
Q-waves) as well as to determine QRS width to ascertain whether the
patient may benefit from resynchronization therapy (see below). A
normal ECG virtually excludes LV systolic dysfunction.