Ischemic heart disease Flashcards
Clinical syndromes of ischemic heart disease
MI
Angina pectoris
Chronic IHD with HF
Sudden cardiac death
Determinants of myocardial oxygen supply
Coronary perfusion pressure
Coronary vascular resistance –> external compression and intrinsic regulation
Determinants of myocardial oxygen demand
Wall stress
HR
Contractility
Coronary artery flow is directly proportional to what?
Perfusion pressure
Coronary artery flow is inversely proportional to what?
Coronary vascular resistance
Value used to approximate coronary perfusion pressure
Aortic diastolic pressure
Regulators of intrinsic control of coronary arterial tone
Accumulation of local metabolites
Endothelium-derived substances
Neural innervation
Change in vascular smooth muscle to increase coronary blood flow
Adenosine binds to receptors to reduce Ca entry into cells, resulting in relaxation and vasodilation
NT receptors on coronary vessels
Alpha adrenergic
Beta-2 adrenergic
Result of stimulation of alpha adrenergic receptors on coronary vessels
Vasoconstriction
Result of stimulation of beta-2 adrenergic receptors on coronary vessels
Vasodilation
Way that beta blockers decrease HR?
Reduce ATP utilization and oxygen consumption
Affect of catecholamines on the heart
Increase force of contraction
Drug class with a negative inotropic effect
Beta blockers
Hemodynamic significance of coronary A narrowing depends on these 2 things
Degree of stenosis
Amount of compensatory vasodilation
Causes of vessel endothelial cell dysfunction
Inappropriate vasoconstriction of coronary A
Loss of normal antithrombotic properties
Angina type precipitated by exercise and relieved with rest or administration of vasodilators. Not usually associated with plaque disruption.
Stable/typical angina
Uncommon episode of myocardial ischemia caused by coronary A spasm. Occurs at rest and responds promptly to vasodilators.
Prinzmetal variant angina
Triggers of Prinzmetal angina
Smoking
Cocaine
Alcohol
Triptans
Pattern of increasingly frequent, prolonged, or severe angina. Caused by disruption of an atherosclerotic plaque
Unstable/crescendo angina
Clinical syndrome of angina pectoris in the absence of significant atherosclerotic coronary stenoses on coronary angiography. Abnormal stress test and abnormal myocardial perfusion imaging.
Microvascular angina
ECG findings during angina episode
ST depression
T wave flattening or inversion
Contrasts used in nuclear stress test
Technetium-99m-labeled compound
Thalium-201
Inotropic agent used in pharmacologic stress test
Dobutamine
Coronary vasodilators used in pharmacologic stress test
Adenosine
Dipyridamole
Hemodynamically significant atherosclerotic lesion results in increased blood flow to non-ischemic areas, which can than move to ischemic areas
Coronary steal syndrome
Possible causes of coronary embolism that can cause MI
Endocarditis
Artificial heart valves
Paradoxical embolism
Timing of onset of ATP depletion in MI
Seconds
Timing of loss of contractility in MI
<2 min
Timing of reduction of ATP to 50% of normal in MI
10 min
Timing of reduction of ATP to 10% of normal in MI
40 min
Timing of irreversible cell injury in MI
20-40 min
Timing of microvascular injury in MI
> 1 hr
Earliest detectable feature of myocyte necrosis that forms the basis of blood tests for irreversible myocyte damage
Disruption of integrity of sarcolemmal membrane
First area of irreversible injury of ischemic myocytes in MI
Subendocardial zone
Complications of MI that can occur within the first 24 hrs
Ventricular arrhythmias
HF
Cardiogenic shock
When will early coagulation necrosis and edema be seen after MI?
4-12 hrs
When will contraction band necrosis and early neutrophilic infiltrates be seen after MI?
12-24 hrs
When will coagulation necrosis with loss of nuclei and striations, and brick neutrophilic infiltrate be seen after MI?
1-3 days
Complication that can occur 1-3 days after MI
Post-infarction fibrinous pericarditis
When will the gross heart have hyperemic border and central softening in the infarct area after MI?
3-7 days
When will the gross heart be maximally soft and microscopically show granulation tissue at margins of infarct area after MI?
7-10 days
When will there be well established granulation tissue after MI?
10-14 days
When will area of infarct after MI appear as a gray white scar?
2-8 wks
Complication that can occur 3-5 days after MI
Interventricular septal rupture
Complication that can occur 5-14 days after MI
Free wall rupture
Complication that can occur 2-7 days after MI
Papillary muscle rupture
Complication that can occur 3-7 days after MI
LV false aneurysm
Complications that can occur 2 wks to several months after MI
Dressler syndrome
CHF
True ventricular aneurysm
Gross histochemical stain that imparts a brick-red color to intact, non-infarcted myocardium where lactate dehydrogenase activity is preserved
Triphenyltetrazolium chloride (TTC)
Morphology of reperfused infarct
Hemorrhagic
Contraction bands in irreversible injured myocytes
What mediates damage in reperfusion injury?
Oxidative stress
Calcium overload
Inflammatory cells
Intensely eosinophilic IC stripes composed of closely packed sarcomeres. Seen in reperfused MI.
Contraction bands
Refers to tissue that demonstrates prolonged systolic dysfunction after an episode of severe, acute, transient ischemia without necrosis –> even after return of normal blood flow
Stunned myocardium
Mechanism of delayed recovery in stunned myocardium
Ca overload and accumulation of oxygen-derived free radicals
Refers to a tissue that manifests chronic ventricular contractile dysfunction due to a persistently reduced blood supply, usually because of multivessel CAD
Hibernating myocardium
Imaging study to distinguish hibernating myocardium from infarcted
FDG-PET –> fluorodeoxyglucose positron emission tomography
Cardiac troponins time to increase after infarct
3-12 hrs after infarction
Time taken for cardiac troponin I to return to normal after infarct
5-10 days
Time taken for cardiac troponin T to return to normal after infarct
5-14 days
Time taken for CK-MB to show increase after infarct
6-12 hrs
Time taken for CK-MB to return to normal levels after infarct
48-72 hrs
Blood test used to assess for reinfarction
CK-MB
Classic ECG pattern in MI
Inverted T waves
Elevated ST segments
New Q waves
ECG finding that correlates with area of coagulation necrosis in MI
New Q waves
ECG finding that correlates with injury to myocardial cells surrounding the areas of necrosis in MI
Elevated ST segments
ECG finding that correlates with areas of ischemia at the periphery of the infarction
Inverted T waves
ECG leads affected in anterior wall infarct or anteroseptal infarct
V1-V2
ECG leads affected in anterolateral infarct
V4-V6
I
aVL
ECG leads affected in lateral wall infarct
I
aVL
ECG leads affected in inferior wall MI
II-III
aVF
ECG leads affected in posterior wall MI
V7-V9
Most common reason for death within 1 hr of MI
Fatal arrhythmia
Complications of MI
Contractile dysfunction
Arrhythmias
Myocardial rupture
Ventricular aneurysm
Pericarditis
Infarct expansion
Mural thrombus
Papillary muscle dysfunction
Chronic IHD
Complication of infarcts involving the inferoseptal myocardium
Heart block
Most common site of ventricular free wall rupture
Anterolateral wall at mid-ventricular level
Result of ventricular free wall rupture
Cardiac tamponade
Result of rupture of ventricular septum
Acute VSD
L to R shunting
New holosystolic murmur
Result of papillary muscle rupture
Acute onset of severe mitral regurgitation
Localized hematoma communicating with the ventricular cavity, a contained free wall rupture
False aneurysm
Late complication of large transmural infarcts that experience early expansion. Bound by scarred myocardium and paradoxically bulges during systole.
Ventricular true aneurysm
Complications of ventricular true aneurysm
Mural thrombus
Arrhythmias
HF
Caused by increased vessel permeability in pericardium resulting in exudate of acute inflammation from underlying myocardial inflammation from MI. Precordial friction rub present on ausculation.
Fibrinous/fibrinohemorrhagic pericarditis
Triad of Dressler syndrome
Fever
Pericarditis
Pericardial effusion post MI
Pathogenesis of Dressler syndrome
Autoantibodies directed against antigens within damaged pericardial tissue –> type II hypersensitivity
Disproportionate stretching, thinning, and dilation of the infarct region due to weakening of necrotic muscle after MI. Associated with mural thrombus.
Infarct expansion
Area at increased risk of infarct expansion after MI
Anteroseptal infarcts
Insidious onset of progressive CHF characterized by LV dilation due to accumulated ischemic myocardial damage and replacement fibrosis, and functional loss of hypertrophied non-infarcted cardiac myocytes.
Chronic IHD
Common cause of restenosis of coronary vessel following PCI
Neointima formation
Vascular smooth muscle cells migrate into stent to form a layer resembling tunica intima. Promoted by macrophages and inflammatory cells.
Neointima formation
Non-coronary artery causes of sudden cardiac death
Cardiomyopathy
MVP
Cocaine
Myocarditis
WPW syndrome
Hereditary ion channelopathies
Hereditary ion channelopathies
Long QT syndrome
Brugada syndrome
Causes of sudden cardiac death in children
Pulmonary infection
AV stenosis
Cardiomyopathies –> usually hypertrophic
WPW syndrome
Reason for sudden cardiac death in long QT syndrome
Increased susceptibility to malignant ventricular arrhythmias
Genes affected by loss of function mutations leading to long QT syndrome
KCNQ1 –> K channel
KCNH2 –> K channel
Genes affected by gain of function mutations leading to long QT syndrome
SCN5A –> Na channel
CAV3 –> Na current, caveolin
3 acute coronary syndromes
Unstable angina
NSTEMI
STEMI