(F) L2: Markers for Cardiac Damage and Function (Part 2) Flashcards
Other Cardiac Markers
- A heme-containing protein (skeletal and cardiac) that binds with oxygen
- Found exclusively in muscle but absent in the circulation
- Its presence in the blood is indicative of muscle damage but not specific to the heart
- An adjunct marker in the early diagnosis of MI
- Is quickly released during muscle damage due to its low MW of 18kDa, serving as the earliest cardiac marker but is not specific
Myoglobin
Other Cardiac Markers
- Is cleared by renal filtration
- Levels are related to muscle mass and activity
- One of the protein markers to diffuse out of ischemic muscle cells
- A screening test for angina and early MI detection
- Is measured in the serum
Myoglobin
Other Cardiac Markers
Elevation: 1-4 hours
Peak: 6-9 hours
Decline: 18-24 hours
Myoglobin
Other Cardiac Markers
- An enzyme present in skeletal but not in cardiac muscle (negative marker)
- Released from damaged muscle at a fairly fixed ratio to myoglobin in cases of cardiac damage
Carbonic Anhydrase
Other Cardiac Markers
If a patient suffering from chest pains produces a (+) result for carbonic anhydrase, what is the interpretation?
The pain MAY NOT be of cardiac origin
Other Cardiac Markers
- An enzyme that catalyzes the first step in glycogenolysis
- Consists of isoenzymes from the liver, muscles, brain, myocardium, and other tissues
Glycogen Phosphorylase
Other Cardiac Markers
This GP isoenzyme is released earlier than other markers under conditions of reversible ischemia
GP-BB (brain)
Other Cardiac Markers
- Is found in all muscles but abundant in the heart
- More sensitive in the diagnosis of acute MI than TnT and myoglobin but is less specific
- Has a low MW of 15kDa and is used for fatty acid metabolism and lipid homeostasis
- An early marker of myocardial damage with same kinetics as myoglobin
Heart-type Fatty Acid-binding Protein (H-FABP)
Other Cardiac Markers
The ratio of myocardial to HFABP is (lower/higher) in the heart
Lower
Other Cardiac Markers
Elevation: 2-4 hours
Peak: 5-10 hours
Decline: 24-36 hours
Heart-type Fatty Acid-binding Protein (H-FABP)
Other Cardiac Markers
- Does not detect myocardial tissue damage as it is not released from damaged myocytes (a unique marker)
- Alters the cobalt-binding of albumin by its N-terminus domain
- A modification of this is caused by free radical formation within minutes of ischemia in the heart
- Has a reduced affinity for metal ions
- Detects ischemia prior to irreversible cell damage
Ischemia-modified Albumin (IMA)
Other Cardiac Markers
- The thick filament of the muscle contractile apparatus (heavy and light chains)
- Not specific for cardiac injuries hence not routinely used as a marker
Myosin
Other Cardiac Markers
- Includes myeloperoxidase (MPO), CRP, myeloid-related protein (MRP-8/14), and pregnancy-associated plasma protein A (PAPP-A)
- Are inferior to troponins in detecting acute MIs
- Is able to predict all-cause mortality and provide independent prognostic information apart from clinical risk factors
Novel Markers of Plaque Instability
TOF: Cardiac markers are always associated with AMIs
False (also caused by cardiac insults that relate to cardiac injury)
- This is a key feature of cardiomyopathies due to genetic issues and stress-related causes
- It comes in the form of apoptosis and/or necrosis
Cell Death
- A pathological state in which the heart fails to adequately supply the metabolic needs of the body due to a decrease in pumping function
- Not only does it come from cardiac overload but also from a complex interplay among genetic, inflammatory, and biological changes acting on cardiac myocytes, cardiac interstitium, or both
Heart Failure
This is the most common cause of heart failure
Coronary Heart Disease (CHD)
Types of Heart Failure
Indicated by pulmonary edema and decreased systemic blood supply
Left-Sided Heart Failure
Types of Heart Failure
Indicated by generalized edema
Right-Sided Heart Failure
Left or Right-sided Heart Failure?
- Most common type
- The heart loses some of its ability to pump out blood after reoxygenation
- Caused by coronary artery disease
Left-Sided
Left or Right-sided Heart Failure?
- The heart loses some of its ability to move oxygen-depleted blood to the lungs to pick up new oxygen
- Most often caused by the other kind of heart failure
- Can also occur even if the other side is apparently normal
Right-Sided
Left or Right-sided Heart Failure?
Symptoms:
1. Paroxysmal nocturnal dyspnea
2. Elevated pulmonary capillary wedge pressure
3. Pulmonary congestion with cough, cackles, wheezes, and blood-tinged sputum
4. Tachypnea
5. Restlessness
6. Tachycardia
7. Exertional dyspnea
8. Fatigue
9. Cyanosis
Left-Sided
Left or Right-sided Heart Failure?
Symptoms:
- Fatigue
- Increased peripheral venous pressure
- Ascites
- Enlarged liver and spleen
- May be secondary to chronic pulmonary problems
- Distended jugular veins
- Anorexia
- Complaints of GI distress
- Weight gain
- Dependent edema
Right-Sided
Lab Tests for Patients with Suspected Heart Failure
This can help determine if anemia or infection may be the cause of heart failure
CBC
Lab Tests for Patients with Suspected Heart Failure
This detects electrolyte imbalance which can cause fluid retention, and it may play a role in the severity of heart failure
Serum Electrolyte Levels
Lab Tests for Patients with Suspected Heart Failure
This can determine if damage to the kidneys, due to hypoperfusion, may be occurring secondary to heart failure
BUN/Creatinine
Lab Tests for Patients with Suspected Heart Failure
Increased levels in both diabetic and non-diabetic patients put them as an increased risk for heart failure
Fasting Glucose
Lab Tests for Patients with Suspected Heart Failure
- Elevated enzymes may indicate if the liver is affected due to heart failure
- It can occur secondary to the inefficiency with which the heart is able to move the venous circulation
Liver Function Tests (AST, ALT, and LD)
Lab Tests for Patients with Suspected Heart Failure
- These 2 analytes are elevated after being released in the heart secondary to the stretch induced by heart failure
- Their levels correlate closely with the severity of heart failure and can be used to differentiate cardiac causes of shortness of breath from primary lung disease
BNP and NT-proBNP Levels
Note: NT-proBNP is the precursor to BNP
B-type Natriuretic Peptide (BNP) and N-terminal pro-B-type Natriuretic Peptide (NT-proBNP)