Page 273 - Concise Pathology for Exam Preparation ( PDFDrive )

258 SECTION II Diseases of Organ Systems

2. Prinzmetal variant angina
(a) Uncommon pattern of episodic angina that occurs at rest and is due to coronary
artery spasm
(b) Attacks unrelated to physical activity, heart rate or blood pressure
(c) Elevation of ST segment (indicative of transmural ischaemia) is typically seen
(d) Responds promptly to vasodilators like nitroglycerin and calcium channel blockers
3. Unstable/crescendo angina
(a) Repeated episodes of pain with progressively increasing (crescendo) frequency
(b) Often occurs at rest and tends to be of prolonged duration
(c) Induced by disruption of an atherosclerotic plaque with superimposed partial
thrombosis and embolization/vasospasm or both
(d) Precedes acute MI in many patients (also called preinfarction angina)

Q. Differentiate among stable angina, Prinzmetal variant angina and
unstable/crescendo angina.

Ans. Differences among stable angina, Prinzmetal variant angina and unstable/crescendo
angina are summarized in Table 11.1.

TABLE 11.1. Differences among stable angina, Prinzmetal variant angina and unstable/
crescendo angina
Features Stable angina Prinzmetal variant angina Unstable/ crescendo angina
Cause Fixed coronary atheroscle- Due to coronary artery spasm Induced by disruption of an athero-
rotic narrowing sclerotic plaque with superim-
posed partial thrombosis and
embolization/vasospasm or both
(dynamic stenosis)
Precipitating Heart vulnerable to isch- Occurs at rest, not related to Often occurs at rest and tends to
factors aemia whenever increased physical activity or emo- be of prolonged duration
demand, ie, physical ac- tional excitement
tivity and emotional ex-
citement
Relieving Relieved by rest/decreased Responds promptly to vasodi- May respond to vasodilators like
factors demand and nitroglycerin lators like nitroglycerin and nitroglycerin and calcium chan-
(decreases cardiac work calcium channel blockers nel blockers
by dilating peripheral vas-
culature)
Outcome Responds to medication Transmural ischaemia, which Harbinger of subsequent acute MI
generally responds to medi- in many patients (also called
cation preinfarction angina)

Q. What is myocardial infarction (MI)? Write briefly on the
aetiopathogenesis, clinical features and morphological evolution of
an acute MI.
Ans. MI is defined as myocardial ischaemia that induces cellular necrosis. It is a leading
cause of death in industrialized nations.

Incidence and Risk Factors
• Ten percent infarcts occur in patients ,40 years and 45% in patients ,65 years (increasing
risk with increasing age)
• Males are more commonly affected than females (the latter show increasing risk with
decreasing oestrogen levels)
• Hypertension, diabetes mellitus, hyperlipoproteinaemias, increased apolipoprotein B,
increased lipoprotein (a), increased C-reactive protein and hyperhomocystinuria are
established risk factors for acute MI

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