7. Angina pectoris Flashcards
Stable angina definition?
Chronic stable angina is manifested as a pattern of predictable, transient chest
discomfort during exertion or emotional stress.
Cause of stable angina?
It is generally caused by fixed, obstructive
atheromatous plaque in one or more coronary arteries.
Symptoms of stable angina?
The pattern of symptoms is
usually related to the degree of stenosis. When atherosclerotic stenoses narrow a coronary artery lumen diameter by more than approximately 70%, the reduced flow capacity may be sufficient to
serve the low cardiac oxygen needs at rest but is insufficient to compensate for any significant
increase in oxygen demand. During physical exertion, for example, activation of the sympathetic
nervous system results in increased heart rate, blood pressure, and contractility, all of which
augment myocardial oxygen consumption.
During the period that oxygen demand?
During the period that oxygen demand exceeds available supply, myocardial ischemia results, often
accompanied by the chest discomfort of angina pectoris. The ischemia and symptoms persist until
the increased demand is alleviated and oxygen balance is restored. Recall that normally, the high
myocardial oxygen demand during exertion is balanced by an increased supply of blood as the
accumulation of local metabolites induces vasodilatation.
For some patients with stable angina?
For some patients with stable angina, alterations in tone play a minimal role in the decreased myocardial
oxygen supply, and the level of physical activity required to precipitate angina is fairly constant.
These patients have fi xedthreshold angina. In other cases, the degree of dynamic obstruction caused
by vasoconstriction or vasospasm plays a more prominent role, and such patients may have variablethreshold angina. For example, on a given day, a patient with variable-threshold angina can exert
herself or himself without chest discomfort, but on another day, the same degree of myocardial
oxygen demand does produce symptoms. The difference reflects alterations in vascular tone over the
sites of fixed stenosis.
According to the type of the predisposing factors we may describe different types of stable angina
pectoris?
- Angina d’effort – evoked by physical activity
- Postprandial angina – after eating
- Emotional angina pectoris – during excitement
- Angina decubitus – after laying in bed
- Angina pectoris inversa (Prinzmetal) – stenocardia occurring at rest, physical activity is not a
causative agent - Status anginosus – is the commutation of attacks. Nearly half the patients with angina
pectoris have normal ECG at rest.
Unstable Angina definition?
Unstable angina pectoris is another painful form of the ischemic heart disease. It
has a very marked beginning of the attack and the spasm occurs at least 3 times per day. Under this
type of angina we may put patients suffering of the chronic stable angina pectoris, in whom a
worsening of attacks occurred with an increase of their number. The attacks usually last for more
than 20 min.
A primary unstable angina pectoris?
A primary unstable angina pectoris represents a condition, in which we do not find any factors that
may lead into worsening of ischemia in patients suffering from this angina. Among the factors that
cause worsening of myocardial ischemia are anemia, fever, infection, tachyarrhythmia, emotional
stress, and hypoxemia. Unstable angina may develop shortly after the occurrence of myocardial
infarction.
The unstable angina pectoris with attacks?
The unstable angina pectoris with attacks occurring at rest is a sign of risk for acute myocardial
infarction. The unstable angina pectoris with evident electrocardiographic changes during the attacks
is always combined with the stenosis of one or more coronary arteries. During the attack spasm
might cause some microscopically changes of the endothelial surface of the atheromatous plate and
hence might lead to a thrombocytic plug. This is why we usually give heparin in case of such attack. In
patients with unstable angina pectoris catheterization is necessary as well as coronarography.
Variant Angina definition?
A small minority of patients manifest episodes of focal coronary artery spasm in the
absence of overt atherosclerotic lesions, and this syndrome is known as variant angina. In this case, intense vasospasm alone reduces coronary oxygen supply and results in angina.
Variant angina( the mechanism)?
The mechanism by which such profound spasm develops is not completely understood but may
involve increased sympathetic activity in combination with endothelial dysfunction. It is thought that
many patients with variant angina may actually have early atherosclerosis manifested only by a
dysfunctional endothelium, because the response to endothelium-dependent vasodilators (e.g., ACh
and serotonin) is often abnormal. Variant angina often occurs at rest because ischemia in this case
results from transient reduction of the coronary oxygen supply.
Silent Ischemia?
Episodes of cardiac ischemia sometimes occur in the absence of perceptible discomfort or pain, and
such instances are referred to as silent ischemia. These asymptomatic episodes can occur in patients
who on other occasions experience typical symptomatic angina. Conversely, in some patients, silent
ischemia may be the only manifestation of CAD. It may be diffi cult to diagnose silent ischemia on
clinical grounds, but its presence can be detected by laboratory techniques such as continuous
ambulatory electrocardiography or it can be elicited by exercise stress testing. One study estimated
that silent ischemic episodes occur in 40% of patients with stable symptomatic angina and in 2.5% to
10% of asymptomatic middle-aged men.
The reason why some episodes of ischemia are silent whereas others are symptomatic
has not been elucidated. The degree of ischemia cannot fully explain the disparity, because even MI
may present without symptoms in some patients. Silent ischemia has been reported to be more
common among diabetic patients (possibly due to impaired pain sensation from peripheral
neuropathy), the elderly, and in women.
Syndrome X?
The term syndrome X refers to patients with typical symptoms of angina pectoris who have no
evidence of significant atherosclerotic coronary stenoses on coronary angiograms. Some of these
patients may show definite laboratory signs of ischemia during exercise testing. It is thought that the resistance vessels (which are too small to be visualized by coronary
angiography) may not dilate appropriately during periods of increased myocardial oxygen demand.
Microvascular dysfunction, vasospasm, and hypersensitive pain perception may each contribute to
this syndrome. Patients with syndrome X have a better prognosis than those with overt
atherosclerotic disease.
