Angina
What are the common conditions that can present with chest pain?
The answer
What are the characteristics of pain due to Angina?
The answer
Clinical Syndrome
Myocardial ischemia
Precordial discomfort, mostly felt beneath sternum
Vague ache to crushing sensation
Radiates to left shoulder, inside left arm, into throat, jaws, epigastrium
Usually persists no more than few minutes (5-10 minutes)
Triggered by physical activity, cold air
Relieved by rest or sublingual Nitroglycerin
What are the characteristics of pain due to Acute myocardial infarction? How does it differ from angina?
The answer
Crushing chest pain with or without radiation.
Lasts longer >20 minutes
Not relieved by rest or Nitroglycerine
Diaphoresis, nausea or vomiting
ECG changes
Cardiac enzymes changes
What are the characteristics of pain due to reflux esophagitis ?
The answer
esophageal spasm may be severe and centered in the chest although it may also bore to the back.
could also be relieved by nitroglycerin
worse in supine position
worse following meals
relieved by antacids or acid blockers
What are the characteristics of pain due to Pericarditis ?
The answer
Precardiac, sharp, persistent.
Worse in recumbent position
Relieved by sitting.
What are the characteristics of pain due to Dissecting aorta ?
The answer
Sharp "tearing" pain radiating to back
What are the characteristics of pain due to Chest wall Lesions ?
The answer
Muscular skeletal pain often is
localized
with point tenderness
it mimics pleuritic pain during inspiration.
What are the characteristics of pain due to Pneumothorax ?
The answer
pain is sudden in onset
localized
sharp
worse on deep breathing and coughing
associated with shortness of breath
Pleuritic pain of pneumonia has the same characteristics.
Describe Coronary arterial system.
The answer
Right and Left main coronary arteries.
Arising from aorta directly
There is some collateral circulation but they mostly behave like end arteries.
How is flow of blood to myocardium is regulated?
The answer
Coronary blood flow during diastole
Increased myocardial activity increases blood flow ( exercise, LV hypertrophy)
Direct from ventricular chamber to myocardium. (small contribution)
Describe the pathogenesis of myocardial ischemia.
The answer
Decreased blood flow
Critical coronary artery obstruction (>70%)
Atherosclerosis
Spasm (Idiopathic, Cocaine)
Increased demand
Increased cardiac work
Calcific Aortic stenosis
Hypertrophic subaortic stenosis
Describe the patho-physiology of myocardial ischemia
The answer
Myocardial O2 demand exceeds the ability of the coronary arteries to supply oxygenated blood.
Coronary sinus blood pH falls/Cellular K loss occurs/EKG abnormalities appear
Ventricular performance deteriorates/LV diastolic pressure rises
Hypoxic metabolites/Discomfort
What are the risk factors for coronary atherosclerosis?
The answer
Hypertension
Diabetes Mellitus
Hypercholesterolemia
Cigarette smoking
Family history of ischemic heart disease
What do you understand by the terms nocturnal angina, crescedndo angina, angina decubitus, unstable angina, Syndrome X
The answer
Nocturnal angina: Angina may occur at night (nocturnal angina) preceded by a dream
Crescendo angina: Attacks of angina increase in frequency to a fatal outcome
Angina decubitus: Angina occuring spontaneously at rest
Unstable angina:
increased intensity
decreased threshold of stimulus
longer duration
occurrence when the patient is sedentary or waking from sleep
Syndrome X:
typical symptoms of angina relieved by rest or nitroglycerin
the exercise test is abnormal
yet the coronary arteriogram is normal.
Prinzmetal angina:
Can angina disappear spontaneously?
The answer:
Yes
if adequate collateral coronary circulation develops
if the ischemic area becomes infarcted
if heart failure or intermittent claudication supervenes and limits
activity
What do you know about HDL and LDL cholesterol?
The answer
HDL:
Good cholesterol.
helps clear the body of cholesterol
by facilitating "reverse cholesterol transport"
LDL:
Bad cholesterol when it exceeds normal levels.
Most atherogenic lipoprotein
Delivers cholesterol to peripheral tissues cells
Triggers cascade of events leading to the development of foam cells
by clearance of a low-affinity "scavenger" pathway
What is the diagnostic strategy for evaluation of angina?
The answer
Diagnosis based primarily on history of characteristic pain
Reversible ischemic ECG changes
Characteristic relief of discomfort with sub-lingual Nitroglycerin
Additional evaluation when the diagnosis is in doubt or interventional therapy is required
What are the ECG changes of angina?
The answer
Reversible ischemic ECG changes are seen during a spontaneous attack.
ST segment depression (typically) ST segment depression >= 0.1 millivolts (1 mm on the ECG when properly
calibrated) lasting >= 0.08 sec.
ST segment elevation
decreased R-wave height
intraventricular or bundle branch conduction disturbances
arrhythmia (usually ventricular extrasystoles).
Between attacks, the ECG at rest could be normal
How is Exercise stress ECG testing useful in the evaluation of angina?
Exercise stress ECG testing:
Response of ECG to graded exercise
Ischemic response supports Angina
With chest pain specificity 70%: sensitivity 90% in men
Negative test is a reliable indicator of no disease.
What is the role of coronary angiogram in evaluation of angina?
The answer
Coronary angiography
Documents the extent of anatomic coronary artery occlusion
Obstruction is physiologically significant when the luminal diameter is reduced >70%
When will you consider exercise test and coronary angiogram in the evaluation of a patient with angina?
The answer
Exercise test:
Diagnosis is not certain and
Patient is stable
Prior to coronary angiogram
Coronary angiogram:
In unstable angina
Diagnosis not certain
Interventional therapy is planned
It would be reasonable to obtain an exercise test and depending on the result of that test, proceed with a cardiac catheterization.
If there is a high prior probability of coronary artery disease, then a negative exercise test may well be considered a false negative and one would go ahead with a Coronary Angiogram .
What is the immediate treatment of angina? How can you increase coronary blood flow immediately?
The answer
Rest (decrease demand for oxygen)
Sublingual nitroglycerine
Organic nitrates are excellent drugs for the treatment of stable angina.
Nitroglycerin is a potent smooth-muscle relaxer and vasodilator.
How soon can you expect relief of pain with use of sublingual nitroglycerine? What are the usual instructions to apatient on the use of the drug?
The answer
Dramatic relief within 1.5 to 3 minutes
Dose may be repeated after 5 minutes three times if there is no relief
Patient should carry the tablets always
Drug looses potency/ refill small amounts frequently
What is the mechanism of action of nitroglycerine?
The answer
Decrease oxygen demand
The organic nitrates decrease ventricular wall stress (oxygen demand) by reducing both preload and after load {wall stress = (P x r)/ (2 x wall thickness)}
This results from a primary action on venous capacitance vessels with a more minor effect on arterioles.
Increase coronary blood flow and exert favorable effects on oxygen supply.
The reduced ventricular pressure during both diastole and systole will decrease extra vascular coronary resistance (compressive forces).
Dilate collateral vessels and produce a small dilatation of stenotic coronary arteries, when the stenosis is eccentric.
The organic nitrates (R-O-NO2) combine with cysteine (R-SH) in the vessel wall to form a nitrosothiol that releases nitric oxide (NO).
What is/are the option to prevent further attacks of angina?
The answer
Long-acting nitrates
nitroglycerine patch
isosorbide dinitrate.
Beta-blockers block sympathetic stimulation of the heart (reduce Systolic pressure, heart rate, contractility, cardiac output) and reduce myocardial O2 demand.
Calcium channel blockers are vasodilators and are useful when angina is due to spasm or associated with Hypertension.
Long-acting nitrates alone or with beta-blockers or with calcium channel blockers or all three can be used based on clinical need.
How can you alter risk factors?
The answer
Smoking: Start smoking cessation programs
Hypertension: Anti-hypertensive medication to lower blood pressure
Hypercholesterolemia: An HMG-CoA reductase inhibitor to lower cholesterol
How does HMG-CoA reductase inhibitor lowers cholesterol?
The answer
Synthesis
HMG-CoA reductase inhibitors block the rate limiting enzyme for the synthesis of cholesterol.
Catabolism
Serum cholesterol levels fall not only from a reduced synthetic rate but from an up-regulation of LDL receptors in hepatocytes and an increased rate of LDL catabolism from the circulating pool.
What is the goal of theapy with HMG-CoA reductase inhibitors? What is the effect on existing atherosclerotic changes?
The goal of this therapy (combined with dietary restrictions) is
to reduce serum cholesterol to <190 mg/dL.
to reduce LDL cholesterol to <100mg/DL
They do reduce the rate of progression of coronary artherosclerotic lesion and increase the frequency of regression.
They do reduce the risk of death due to coronary artery disease and risk of nonfatal myocardial infarction.
What options do we have to prevent development of thrombosis in a coronary artery with atheromatous changes?
The answer
Aspirin reduces the risk of coronary thrombosis ( heart attack ) in patients with coronary artery disease'
There is a strong indication for daily aspirin (81 mg/day) as prophylactic therapy.
Aspirin causes decreased platelet aggregation.
by irreversible inhibition of platelet cyclooxygenase and decreased thromboxane A2 production
What are the options we have to relieve mechanical obstruction of Coronary arteries ?
The answer
Angioplasty:
Involves insertion of a balloon tipped catheter into an artery at the site of partial obstruction
Inflation of the balloon can rupture the intima and media and dramatically dilate the obstruction
In a patient with suitable anatomic lesions
Stents can be placed can be placed to reduce reocclusion
Coronary Artery Bypass Surgery
Venous graft
Internal mammary artery graft