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Ischemic Heart Disease
CVS3
Hisham Alkhalidi
Ischemic Heart Disease
A group of related syndromes resulting from
myocardial ischemia
Ischemic Heart Disease
• The vast majority of ischemic heart disease is
due to coronary artery atherosclerosis
• Less frequent contributions of:
– vasospasm
– vasculitis
• Is it exactly the same as coronary artery
disease (CAD)?
– Frequently yes
Ischemic Heart Disease
Angina pectoris
• Chest pain:
– Can radiate down the left arm or to the left jaw
(referred pain)
– Due to inadequate perfusion
– Duration and severity is not sufficient for
infarction
Ischemic Heart Disease
Stable angina
– Occurring reliably after certain levels of exertion
– Typically due to atherosclerotic disease with ≥75%
(critical stenosis) fixed chronic stable stenosis
Ischemic Heart Disease
Unstable angina
• Unstable (occurring with progressively less exertion
or even at rest)
• Results from a small fissure or rupture of
atherosclerotic plaque triggering:
•
•
•
•
Platelet aggregation
Vasoconstriction
Formation of a mural thrombus that may not be occlusive
Usually proceed MI
Ischemic Heart Disease
Variant angina
• Vessel spasm or Prinzmetal angina
• Without fixed atherosclerotic disease
• The etiology is not clear
Ischemic Heart Disease
Myocardial infarction
• The severity or duration of ischemia is enough
to cause cardiac muscle death
• Typically results from acute thromboses that
follow plaque disruption
Ischemic Heart Disease
MI types
• Transmural
– Full thickness (>50% of the wall)
• Subendocardial
– Inner 1/3 of myocardium
– Two mechanisms:
• Fixed atherosclerosis but with increased demand,
vasospasm or hypotension OR
• Evolving transmural with relieve of the obstruction
(often multifocal)
Ischemic Heart Disease
MI, common locations
– In Right dominent coronary artery heart (90% of
population):
• 2 cm proximal LAD (up to 50%)
– anterior left ventricle
– anterior septum
– apex circumferentially
• Left circumflex ( up to 20%)
– infarct involves lateral left ventricle except the apex.
• 1st and last thirds of RCA (up to 40%)
– posterior left ventricle
– posterior septum
– right ventricular free wall, sometime
Ischemic Heart Disease
Ischemia to myocardium rapidly (minutes) leads
to loss of function and causes necrosis after 20
to 40 minutes
Ischemic Heart Disease
Clinical picture of MI
• Severe, crushing substernal chest pain or
discomfort that can radiate to the neck, jaw,
epigastrium, or left arm
• Diaphoresis
• Nausea
• Dyspnea
• Can be silent (DM, old age)
Ischemic Heart Disease
ECG
• Changes such as:
– Q waves (indicating transmural infarcts)
– ST-segment abnormalities
– T-wave inversion
• Arrhythmias
Ischemic Heart Disease
Laboratory evaluation
• Cardiac troponins T and I (TnT, TnI)
• Creatine kinase (CK, and more specifically the
myocardial-specific isoform, CK-MB)
• Lactate dehydrogenase
• Myoglobin
Troponins and CK-MB have high specificity and
sensitivity for myocardial damage
Ischemic Heart Disease
Laboratory evaluation
• TnI and TnT are not normally detectable in the
circulation
• After acute MI both troponins:
– Become detectable after 2 to 4 hours
– Peak at 48 hours
– Their levels remain elevated for 7 to 10 days
Ischemic Heart Disease
Laboratory evaluation
• CK-MB is the second best marker
• CK-MB activity:
– Begins to rise within 2 to 4 hours of MI
– Peaks at 24 to 48 hours
– Returns to normal within approximately 72 hours
Ischemic Heart Disease
Complications of MI
• At least 80% will suffer:
– Cardiogenic shock (>40% infarct of LV)
– Congestive heart failureCHF
– Arrhythmia
– Rupture of ventricle, free wall, septum, or
papillary muscle
– Aneurysm formation,
– Mural thrombus, potentially soursce of emboli
– Pericarditis
Ischemic Heart Disease
MI death and complications rates
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•
•
•
25% die, presumably due to arrythmia
10% of the rest will die within a month
80-90% will develop complications
Overall 30% die in the 1st year and then 10%
per year
Chronic ischemic heart disease
• Progressive heart failure due to ischemic
injury, either from:
– prior infarction(s) (most common)
– chronic low-grade ischemia
Ischemic Heart Disease
Sudden cardiac death
• Unexpected death from cardiac causes either
without symptoms or within 1 to 24 hours of
symptom onset (different authors use
different time points)
• Results from a fatal arrhythmia, most
commonly in patients with severe coronary
artery disease
Ischemic Heart Disease
Acute coronary syndrome
• is applied to three catastrophic manifestations
of IHD:
– Unstable angina
– Acute MI
– Sudden cardiac death