Page 238 - Color Atlas Of Pathophysiology (S Silbernagl Et Al, Thieme 2000)

Pericardial Diseases
The pericardium envelopes the heart as a dou- causing constrictive pericarditis (conP.). This
ble-layered, flexible sac: 15–50 mL of a serous results in the ventricular compliance (= lusi-
fluid serves as lubricating film between the tropic = relaxation) curve rising much more
two pericardial layers. The intrapericardial steeply (→ A2, R becomes R′), so that the dias-
pressure (P per ) is dependent on respiration tolic pressure in the ventricle rises again
and varies between + 3.5 and – 3.5 mmHg. steeply after a brief fall (→ A1, dip with short
The cause of acute pericarditis (P.) may be and rapid early diastolic filling) to a plateau
infectious (e.g., echovirus, tuberculosis) or non- (→ A1). The y descent of the CVP is more
infectious (e.g., uremia, transmural infarction, marked in constrictive pericarditis, because—
tumor, radiotherapy). The usual stages of P. in contrast to pericardial tamponade—there is
are: 1) vasodilation with increased fluid accu- a greater pressure gradient between atrium
mulation (serous P.); 2) increased vascular per-
and ventricle in early diastole. It is important
Heart and Circulation cluding fibrinogen or fibrin, in the fluid in- tamponade (but not in constrictive pericardi-
in the differential diagnosis that in pericardial
meability so that the content of proteins, in-
tis) the systolic blood pressure during inspira-
creases (serofibrinous P.); and 3) immigration
of leukocytes (purulent P.). Bleeding is also a
tion falls by more than 10 (normally 5) mmHg
during inspiration, because the increased ve-
possible cause (hemorrhagic P.).
nous return, increased during inspiration, pro-
Symptoms of an acute P. are chest pain (ag-
toward the left ventricle, thus lowering its
ver, pericardial rub on auscultation, and an ab-
normal ECG (ST segment elevation caused by
stroke volume more than normal, resulting in
7 gravated during inspiration and coughing), fe- duces a bulge in the interventricular septum
associated inflammatory response of the sub- a “pulsus paradoxus”. On the other hand, the
endocardial myocardium; PR segment depres- Kussmaul sign, an inspiratory rise in central
sionbecauseofabnormalatrialdepolarization). venous pressure, rather than the normal fall,
Pericardial effusion (> 50 mL of fluid which is characteristic of constrictive pericarditis.
can be measured by echocardiography) can de- In both constrictive pericarditis and pericar-
velop with any acute P. If more than ca. 200 mL dial tamponade, diastolic ventricular filling is
accumulates in acute cases (e.g., hemorrhage), decreased, causing, among other things, a rise
P per rises steeply because of the rigidity of the in venous pressure. In the pulmonary veins this
pericardial sac (for consequences, see below). gives rise to dyspnea and rales (pulmonary
But if effusion accumulates in chronic cases, edema). The increased systemic venous pressure
the pericardial sac stretches gradually so that (congested neck veins; → A) leads to hepato-
in given circumstances 1–2 L can be contained megaly, ascites, and peripheral edema.
without significant rise in P per . The cardiac output is diminished in constric-
Serious complications of acute P. and of peri- tive pericarditis and pericardial tamponade as
cardial effusion are pericardial tamponade and a result of the decreased ventricular filling
constricitive pericarditis, both of which impair (→ A, orange area). Due to increased sym-
cardiac filling (→ A). Causes of pericardial tam- pathetic activity, tachycardia and centraliza-
ponade (PT) include tumorinfiltration and viral tion of the circulation develops (shock;
or uremic P. as well as ventricular rupture after → p. 230ff.). The combination of a fall in blood
myocardial infarction or chest trauma. A conse- pressure, tachycardia, and compression of the
quence of pericardial tamponade is a rise in coronary arteries results in myocardial ische-
ventricular pressure throughout systole to the mia with characterstic ECG changes (→ A4,5;
level of P per . The normal “y descent (or dip)” in → p. 221F). If pericardial tamponade (especial-
the central venous pressure (CVP; → p.179 A3), ly if acute) is not removed by a pericardial tap,
which represents the fall in pressure after the diastolic ventricular pressure rises ever
opening of the tricuspid valve, is flattened out higher due to a vicious circle, and the cardiac
so that no such dip is recorded (see below). pumping action ceases (→ A3). constrictive
228 Scarring and calcification of the pericardial pericarditis is treated by means of surgical re-
layers may occur after viral or tubercular P., section of the pericardium (pericardiectomy).
Silbernagl/Lang, Color Atlas of Pathophysiology © 2000 Thieme
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