What is angina pectoris? Angina pectoris is chest pain that’s felt due to lack of blood flow to the heart muscle. Angina’s most often caused by atherosclerosis, but may also be due to heart muscle growth. Find more videos at http://osms.it/more.
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Content
5.27 -> Angina comes from the latin angere, which
means to strangle, and pectoris comes from
9.67 -> pectus, meaning chest—so angina pectoris
loosely translates to “strangling of the
15.059 -> chest”, which actually makes a lot of sense,
because angina pectoris is caused by reduced
19.42 -> blood flow which causes ischemia to the heart
muscle, or lack of oxygen to the heart, almost
24.66 -> like the heart’s being strangled which causes
terrible chest pain.
29.33 -> Stable angina or chronic angina is the most
common type of angina and it usually happens
33.73 -> when the patient has greater than or equal
to 70% stenosis, meaning 70% of the artery
38.66 -> is blocked by plaque buildup.
41.14 -> This small opening that blood flows through
might be enough to supply the heart during
44.53 -> rest, but if the body demands more blood and
oxygen, like during exercise or stressful
48.88 -> situations, the heart has to work harder,
and therefore needs more blood and oxygen
53.79 -> itself.
54.79 -> It’s during these time of exertion or emotional
stress that people with stable angina have
59.61 -> chest pain, since the blood flow isn’t meeting
the metabolic demands of the heart muscle,
63.579 -> or myocardium.
65.58 -> But the pain usually goes away with rest.
68.259 -> In the majority of cases, the underlying cause
of stable angina is atherosclerosis of one
72.939 -> or more the coronary arteries—arteries supplying
blood to the heart muscles.
78.159 -> Other heart conditions that might lead to
stable angina are ones that cause a thickened
81.18 -> heart muscle wall, which would require more
oxygen.
84.49 -> This increase in muscle size can be due to
hypertrophic cardiomyopathy from a genetic
88.729 -> cause, or as a result from the heart having
to pump against higher pressures, as is the
92.819 -> case in aortic stenosis, which is a narrowing
of the aortic valve, or hypertension.
98.92 -> These larger, thicker heart muscles require
more oxygen, and if the patients can’t meet
103.079 -> increasing demands, they feel pain in the
form of angina.
107.079 -> Whatever the case, the heart needs blood,
and if we look at the heart wall, there’s
110.759 -> three layers—the outermost layer, the epicardium,
then the myocardium in the middle, and the
115.509 -> endocardium inside the heart.
118.039 -> The coronary arteries start up in the epicardium,
and then dive down and supply all the heart
122.149 -> tissue.
123.149 -> If blood flow’s reduced or the myocardium
is thicker, blood has a harder time reaching
128.16 -> this deeper layer just under the endocardium,
called the subendocardium.
133.069 -> Therefore the classic finding with angina
is subendocardial ischemia, meaning less oxygen
137.87 -> is reaching the region just under the endocardium.
141.35 -> This ischemia is thought to trigger release
of adenosine, bradykinin, and other molecules
145.51 -> that stimulate nerve fibers in the myocardium
that result in the sensation of pain.
151.06 -> That chest pain is usually described as feeling
like pressure or squeezing and it can radiate
155.49 -> to the left arm, jaw, shoulders, and back,
and sometimes is accompanied by shortness
159.78 -> of breath and diaphoresis or sweating.
163.14 -> Usually the pain and symptoms last less than
20 minutes and subside after the exertion
167.24 -> or stress is taken away, and therefore the
heart muscle isn’t demanding as much blood.
171.92 -> Now, unlike stable angina which describes
when patients have pain only during periods
176.18 -> of exertion or stress, but not during rest,
there is also unstable angina which is when
181.23 -> patients have pain during exercise or stress
as well as during rest—it never really goes
185.9 -> away.
187.56 -> Unstable angina is usually caused by rupture
of atherosclerotic plaque with thrombosis,
192.37 -> meaning a blood clot forms on top of a mound
of plaque.
196.03 -> Although the occlusion might not block the
entire vessel, there is now even less room
200.01 -> left for blood to flow by, and the heart tissue
is starting to feel starved for oxygen even
203.95 -> while pumping at a normal rate.
206.75 -> Unstable angina, for the same reason as stable
angina, involves subendocardial ischemia and
211.21 -> it should be treated as an emergency, because
patients are at a high risk of progressing
215.17 -> to myocardial infarction, or heart attack.
218.74 -> The key distinction is that unstable angina
means that the heart tissue is alive but ischemic
223.29 -> or starving for oxygen, whereas myocardial
infarction means that the areas of heart tissue
227.95 -> have already begun to necrose or die.
231.87 -> Now a third type of angina is vasospastic
angina, also known as prinzmetal angina, and
237.56 -> patients may or may not also have atherosclerosis.
240.6 -> Ischemia, and resulting chest pain is due
to coronary artery vasospasms, meaning the
245.94 -> smooth muscles around the arteries constrict
extremely tightly and reduce blood flow enough
250.57 -> to cause ischemia.
252.82 -> Episodes of vasospastic angina don’t correlate
with exertion and can happen anytime, including
258.12 -> at rest.
259.989 -> The underlying mechanism causing vasospasms
isn’t well understood, but likely involves
264.84 -> vasoconstrictors like platelet thromboxane
A2.
269.889 -> Unlike both stable and unstable angina, in
this case the coronary artery’s constricted
274.349 -> so severely that all layers of the heart wall
being supplied are affected, therefore it’s
278.9 -> referred to as transmural ischemia.
282.479 -> Alright, so if we line these three up side-to-side,
there’s some important clinical similarities
288.13 -> and differences.
289.13 -> First, it’s super important to remember
that in each case, the injury to cardiomyocytes
293.59 -> isn’t permanent, meaning it’s reversible
and the cardiomyocytes don’t die (which
298.469 -> is how this differs from myocardial infarction).
300.759 -> On an electrocardiogram, or ECG, both stable
and unstable angina show an ST-segment depression
307.87 -> since ischemia’s limited to the subendocardium.
310.62 -> In contrast, vasospastic angina shows ST-segment
elevation due to transmural ischemia.
318.41 -> Rest tends to relieve stable angina, whereas
unstable angina and vasospastic angina can
323.169 -> occur anytime, including at rest.
326.55 -> In terms of medications, all three can be
treated with Nitroglycerin which is a vasodilator
331.37 -> that increases blood vessel diameter to allow
more blood flow.
334.77 -> In addition, vasospastic angina also responds
to calcium channel blockers.
