SM 128 Ischemic Heart Disease Flashcards
Why do significant reductions in lumen size not occur until Atherosclerosis is well advanced?
Due to “positive remodeling”
Initial growth of the plaque occurs away from the lumen so significant obstruction takes a long time to develop
How does Coronary Artery Bypass Surgery work (CABG)?
Treats angina by using venous or arterial conduits to bypass an occlusion in a stenotic region of a vein and restore bloodflow to ischemic myocardium
How can angina be confirmed?
Stress test and searching for ECG, Echo, or scintigraphic evidence of MI
What kind of EKG alterations are seen in Acute Coronary Disease?
ST depression or elevation
What is the sensitivity and specificity of Exercise stress testing?
Sensitivity = 50 - 80% Specificity = 50 - 90%
High variation because not all patients develop an ECG change, which is used as a readout for stress tests, and patients vary in extent of disease
How does Magnetic Resonance Cardiac Imaging work?
A contrast agent is given after pharmacological vasodilation of the heart is induced, to determine regional variations in myocardial blood flow
Also sees heart size and myocardial viability
What strategies are used to control Angina?
MLP
Myocardial revascularization
Lifestyle changes
Pharmacologic treatments
What changes are expected on an exercise stress test in a patient with Ischemic Heart Disease?
Expect to see flat ST interval on an ECG which indicates Ischemia
ST interval should return to normal with rest
What does uniform uptake of a tracer in both stressed and resting conditions on Stress MPI indicate?
Suggests that myocardial accumulation of tracer and the resulting radioactivity is proportional to blood flow
Results are normal; abnormal would be diminished perfusion/radioactivity during stress
What are some of the advantages of a stress echo?
Stress echo’s can detect wall motion abnormalities using real time information
Do not need a computer to process information
Portable and can be done at at patients bedside
No radiation involved
How does Coronary Angiography work?
In Coronary Angiography, a radiographic contrast is injected into the left ventricle to visualize contractile function through the ejection fraction
How do Calcium channel blockers treat Angina?
Decrease entry of Calcium ions into myocardial cells, reducing heart rate, blood pressure, and contractility
Help prevent vasospasm
What are “anginal equivalents” and where are they found?
Symptoms of myocardial ischemia other than angina, such as dyspnea, nausea, fatigue
Found in women, diabetics, elderly
What does Magnetic Resonance Cardiac imaging primarily visualize?
Myocardial blood flow
How critical is a physical exam for diagnosing Ischemic Heart Disease?
Physical exam is less important because many patients appear normal or do not experience angina unless they are exerting themselves
What is the first event to follow a reduction in myocardial blood flow and how long does it take to manifest?
Abnormalities in regional diastolic relaxation occur, within seconds of a reduction in regional blood flow
What is Coronary Atherosclerosis?
A manifestation of systemic disease involving the arterial system, that leads to the asymptomatic process of atherosclerotic plaque formation
How do Lipid Lowering Agents treat Angina?
By lowering LDL, and raising HDL, statins slow the progression of Atherosclerosis and prevent heart attacks in patients with chronic ischemic heart disease
Used in combination with Ezetimbe, Bile Acid sequestrants, and PCSK9 inhibitors
How does Ranolazine treat Angina?
Ranolazine reduces myocardial ischemia by closing the inward Na gate and compensating for the Na/Ca exchange, causing anti Anginal effects
What is Angina Pectoris?
An uncomfortable sensation that occurs when coronary blood flow is unable to meet myocardial oxygen demand
Triggering Event Location Character Duration Associated Manifestations Response to Therapy
What is “negative remodeling”?
Progressive narrowing of the coronary lumen leading to inability of the vessel to meet the demands of tissue under stress
Atypical responses to angina also occur at rest, due to spontaneous constriction of an artery
How do Beta Adrenoreceptor Blockers treat Angina?
Beta Blockers are competitive antagonists to Epi and Norepi, causing a decrease in HR, Arterial BP, and contractility
In turn, reduce Myocardial O2 consumption and improve Angina
How can Coronary Artery Disease be prevented?
Effective reduction of LDL, reducing BP, smoking cessation, weight loss, alcohol moderation, and increased physical activity help control Coronary Artery Disease
When is myocardial revascularization an appropriate treatment for Angina?
Revascularization should be considered if:
Medical therapy fails
Patient is intolerant to drugs
Prolongation of life ie “compelling anatomy:
Severe cardiac dysfunction
What are modifiable risk factors for Atherothrombosis?
Hypertension Smoking Hyperlipidemia Diabetes Physical inactivity Obesity
In what populations is Angina Pectoris able to develop “unprovoked”?
Women and diabetic patients
How does Percutaneous Transluminal Coronary Angioplasty work (PTCA)?
Improves coronary blood flow by dilation and implantation of a small stent in a dilated arterial segment to help maintain patency of an otherwise occluded segment
Where is Angina Pectoris found?
Not always typical in location
What does Cardiac Catheterization assess?
Cardiac catheterization assess the pressures and flows in all four chambers of the heart, as well as the valvular function of the heart
What would low tracer uptake in both stressed and resting conditions on a stress MPI indicate?
Low uptake during stress suggests Ischemia, while the low uptake during rest is normal
What risk factor also indicates the presence of coronary atherosclerosis?
Diabetes Mellitus
How do Nitrates treat Angina?
Use the Nitric Oxide pathway to improve Angina via multiple mechanisms of coronary and systemic venous and arterial dilation
What are the two modes of clinical presentation of Coronary Atherosclerosis?
Acute Coronary Syndrome and “negative remodeling”
What are the clinical types of Angina?
Chronic/Stable
Atypical
Anginal Equivalents and Silent Ischemia
How do antiplatelet agents treat Angina?
Aspirin and Clopidogrel, alone or together, reduce platelet aggregation via different mechanisms
Both treat and prevent atherothrombotic events
What is the gold standard diagnostic test for coronary artery disease?
Coronary Angiography is the gold standard diagnostic test for defining the extent and severity of coronary artery disease
What is Acute Coronary Syndrome?
A sudden reduction in blood flow due to rupture of a plaque
What are the therapeutic goals in managing Angina?
Symptom control, preventing life threatening complications, and preventing the progression of the disease
How critical is a history for diagnosing Ischemic Heart Disease?
History taking is critical for diagnosing IHD and can be diagnostic on its own
What is CT angiography?
A non-invasive diagnostic procedure that can display multiple “slices” of the heart, which visualize anatomy and ventricular function
What are the classifications for Angina Pectoris?
Class I through IV
I = angina on serious exertion only II = angina slightly limits day to day activity III = angina with all day to day activity IV = angina with any physical activity at all
What would a fixed deficit in tracer uptake on a stress MPI indicate and why?
A fixed deficit in both stressed and resting conditions indicates a blockage in a vessel preventing the tracer from being taken up by the vessel
What are nonmodifiable risk factors for Atherothrombosis?
Age, Sex, Heredity
What is the order of events in changes leading to angina?
First, myocardial infarction leads to abnormalities in diastolic relaxation within seconds
Second, regional systolic dysfunction occurs
Third, alterations in the filling of the heart lead to changes on the EKG, such as ST depression or elevation
Finally, a patient experiences angina
How do Renin-Angiotensin inhibitors treat Angina?
ACE inhibitors and Angiotensin Receptor antagonists lower BP and slow the progression of atherosclerosis
