Transcript CARDIAC DIAGNOSTIC TESTING

BY
DR : RAMY A. SAMY
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CARDIAC BIOMARKERS
RADIOLOGY
ECG AND STRESS ECG
ECHO
Cardiac biomarkers
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CK (CPK)
CK-MB
Troponin-I/T
LD (LDH)
Myoglobin
ALT/AST
Others
Creatine Kinase
an enzyme expressed in a number of tissues.
Function: it catalyses the conversion of creatine to
phosphocreatine degrading ATP to ADP
The CK enzyme consists of two subunits,
• B (brain type) or
• M (muscle type),
• Making three different isoenzymes: CK-MM, CKBB and CK-MB
ck
CK-MB
Troponin
• Troponin is a complex of three regulatory
proteins that is integral to non-smooth muscle
contraction in skeletal as well as cardiac muscle
• Troponin has three subunits, TnC, TnT, and TnI
–Troponin-C binds to calcium ions to
produce a conformational change in TnI
–Troponin-T binds to tropomyosin,
interlocking them to form a troponintropomyosin complex
–Troponin-I binds to actin in thin
myofilaments to hold the troponintropomyosin complex in place
• Thus far, studies have failed to
find a source of Troponin-I
outside the heart, but have
found some Troponin-T in
skeletal muscle
• Because of it’s increased
specificity, our lab uses
Troponin-I
• Troponin-I levels begin to rise
after
onset of MI and roughly 80% of patients with
AMI will have positive values at 3 hours
• Elevations in Troponin-I and Troponin-T can
persist for up to
after MI
• Therefore it has good utility for retrospectively
diagnosing AMI
• Remember, CK-MB returns to baseline by 48
hours
• Troponin release can also be precipitated by
other conditions that cause myocardial damage
• LD (LDH)
– Used in the past along with aminotransferases to
diagnose AMI. LD is non-specific for cardiac
tissue, which contains LD-1.
– However, pancreas, kidney, stomach tissue and
red cells also contain LD-1.
– In the setting of AMI, LD rises at about 10 hours,
peaks at 24-48 hours, and remains elevated for
up to 8 days
• Myoglobin
– small-size heme protein released from all
damaged tissues. Increases often occur
more rapidly than TI and CK.
– Not utilized often for AMI/cardiac damage
assessment because of its very rapid
metabolism (short plasma half-life) causing
short burst increases that are difficult to
assess clinically, as well as its lack of
specificity for cardiac tissue.
• ALT/AST
– not used for assessment of myocardial damage any longer
• H-FABP
– Heart-type fatty acid binding protein
– Kinetically similar to myoglobin but more specific to cardiac
tissue which contains a greater percentage of this protein
than skeletal muscle
– May also have role in prediction- prognosis in patients with
NSTEMI
– Current studies ongoing to further evaluate its utility
Radiology
CARDIAC CATHETERIZATION
• DESCRIPTION
• These procedures involve insertion of a specialized
catheter into the systemic circulation and
advancement into individual coronary arteries or
retrograde advancement across the aortic valve
and into the LV.
• Following placement of the catheter in the desired
location, hemodynamic data can be acquired, and
angiography can be performed by injection of
radiocontrast dye and fluoroscopic image
acquisition.
• Catheterization is primarily used to diagnose
obstructive coronary artery disease, assess its
severity, and design the optimal medical and/or
surgical treatment.
NUCLEAR IMAGING
NUCLEAR IMAGING
• Nuclear myocardial perfusion imaging is
occasionally obtained in conjunction with stress
testing to further aid diagnostic accuracy.
• This is especially useful in patients with
baseline ECG abnormalities.
• The technique involves injection of a
radioactive isotope that is extracted from
plasma by viable myocardium. (technetium
99m [99mTc] sestamibi or 99mTc tetrofosmin),
• The images are acquired with a special camera
that captures radioactive emissions.
• The intensity of the image is proportional to
the perfusion of the myocardium
• Images are acquired both at rest and after peakexercise or vasodilator infusion .
• The images are then compared, and stressinduced perfusion defects identified.
• The defects correlate with the presence of
epicardial coronary artery disease.
• The use of myocardial perfusion imaging
increases the accuracy of stress testing for
diagnosing coronary artery disease.
Gamma Camera
• ELECTROCARDIOGRAM
CHAMBER ENLARGEMENT
LEFT ATRIAL ENLARGEMENT CRITERIA
RIGHT ATRIAL ENLARGEMENT CRITERIA
ECG CRITERIA FOR LEFT VENTRICULAR
HYPERTROPHY
ECG CRITERIA FOR RIGHT VENTRICULAR
HYPERTROPHY
 ECG CRITERIA FOR ACUTE MYOCARDIAL
INFARCTION
EXERCISE STRESS TESTING
EXERCISE STRESS TESTING
• DESCRIPTION :
• The exercise stress test (EST) is most
commonly used to diagnose coronary artery
disease in low- to intermediate-risk patients.
• The EST is also used to assess exercise capacity
and functional reserve in patients with known
coronary artery disease.
• The test employs physical exercise (treadmill,
stationary bicycle, or arm crank) in a controlled
environment coupled with continuous telemetry
monitoring and serial electrocardiographs
(ECGs) to evaluate for evidence of myocardial
ischemia.
Serial hemodynamic measurements are also
obtained to determine the physiologic response
to exercise.
• Stress testing is often performed in conjunction
with an imaging modality to increase the
sensitivity for detecting coronary artery
disease.
INDICATIONS
To diagnose coronary artery disease (CAD) in
adult patients
To risk stratify
To assess the efficacy of medical treatment
To evaluate exercise capacity and functional
status in patients with valvular heart disease.
CONTRAINDICATIONS
• Absolute contraindications to stress testing
include the following:
 Acute MI (within 2 days)
 High-risk unstable angina
 Uncontrolled cardiac arrhythmias
 Symptomatic severe aortic stenosis
 Decompensated heart failure
 Acute pulmonary embolus
 Acute myocarditis or pericarditis
 Acute aortic dissection
Relative contraindications to stress testing include:
 Known left main coronary artery stenosis
 Moderate stenotic valvular heart disease
 Electrolyte abnormalities
 Severe arterial hypertension (systolic blood
pressure [SBP] >200 or diastolic blood pressure
[DBP] >100)
 Tachyarrhythmias or bradyarrhythmias
 Hypertrophic cardiomyopathy
 High-grade atrioventricular (AV) block
 Exercise intolerance
DISCONTINUING A TEST
Absolute indications for discontinuing an exercise test include the
following:
 Decrease in SBP >10 mm Hg from baseline
 Moderate to severe angina
 Development of central nervous system abnormalities (ie, ataxia,
dizziness)
 cyanosis or pallor
 difficulty in monitoring the ECG or blood pressure
 Sustained ventricular tachycardia
 ST elevation >1 mm in any lead without significant Q waves
ECHOCARDIOGRAPHY
DESCRIPTION
• Echocardiography is a noninvasive modality that
utilizes reflected sound waves to image the
heart and define both its structure and
function.
• Two-dimensional echocardiography is used to
assess cardiac structure, left ventricular
function, valvular integrity and function, and
the pericardium. It also permits calculation of
chamber dimensions, areas, and volumes.
• Color flow imaging assigns different colors to
blood that is moving toward the transducer
(red) and away from the transducer (blue).
• It is used to detect abnormal flow such as
valvular regurgitation, intraventricular shunts,
and obstruction of flow within or between the
cardiac chambers
• Contrast echocardiography
• Agitated saline
• INDICATIONS
 Evaluation of murmurs and valvular heart disease.
 Evalution of patients with established valvular heart disease.
 Evaluation of prosthetic heart valves .
 Chest pain and suspected ischemic heart disease.
 Left ventricular
miscellaneous.
function,
pericardial
 Pulmonary disease.
 Arrhythmias , palpitations and syncope .
disease,
and
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TRANSESOPHAGEAL ECHOCARDIOGRAPHY
• A similar study to a surface echocardiogram,
however, the ultrasound probe is passed into
the esophagus to examine the cardiac
structures in close proximity.
• Transesophageal echocardiography offers
superior assessment of cardiac anatomy and
physiology because of the proximity of the
probe.
STRESS ECHOCARDIOGRAPHY
• Echocardiography is often used as an imaging
modality to increase the sensitivity and
specificity of exercise
• stress tests for the detection of CAD.
• Stress echocardiography also assesses
myocardial viability in patients with known
CAD and in whom revascularization is being
considered.