Sources: Disturbances Of The Heart
The venous pressure, after a long neglect, is now again being
studied, and its determination is urged as of diagnostic and
Hooker [Footnote: Hooker: Am. Jour. Physiol., March, 1916.] says
there is a progressive rise of venous pressure from youth to old
age. He has described an apparatus [Footnote: Hooker: Am. Jour.
Physiol., 1914, xxxv, 73.] which allows of the reading of the blood
pressure in a vein of the hand when the arm is at absolute rest, and
best with the patient in bed and reclining at an angle of 45
degrees. He finds that just before death there is a rapid rise in
venous pressure, or a continuously high pressure above the 20 cm. of
water level, and he believes that a venous pressure continuously
above this 20 cm. of water limit which is not lowered by digitalis
or other means is serious; and that the heart cannot long stand such
a condition. These dangerous rises in venous pressure are generally
coincident with a fall of systolic arterial pressure, although there
may be no constant relation between the two. He also finds that with
an increase of venous pressure the urinary output decreases. This,
of course, shows venous stasis in the kidneys as well as a probable
lowering of arterial pressure.
Clark [Footnote: Clark, A. D.: A Study of the Diagnostic and
Prognostic Significance of Venous Pressure Observations in Cardiac
Disease, Arch. Int. Med., October, 1915, p. 587.] did not find that
venesection prevented a subsequent rapid rise in venous pressure in
dire cases. From his investigations he concludes that a venous
pressure of 20 cm. of water is a danger limit between compensation
and decompensation of the heart, and a rise above this point will
precede the clinical signs of decompensation.
Hooker also found that there are daily variations of venous pressure
from 10 to 20 cm. of water, with an average of 15 cm., while in
sleep it falls 7 or 8 cm.
It seems probable that there may be a special nervous mechanism of
the veins which may increase the blood pressure in them as
epinephrin solution may cause some constriction.
Wiggers [Footnote: Wiggers C. J.: The Supravascular Venous Pulse in
Man, THE JOURNAL. A.M.A., May 1, 1915, p. 1485.] describes a method
of taking and interpreting the supraclavicular venous pulse. He also
[Footnote: Wiggers C. J.: The Contour of the Normal Arterial Pulse,
THE JOURNAL. A.M.A., April 24, 1915, p. 1380.] carefully describes
the readings and the different phases of normal arterial pulse, and
urges that it should be remembered that "the pulse as palpated or
recorded from any artery is the variation in the arterial volume
produced by the intra-arterial pressure change at that point."
A quick method of estimating the venous pressure by lowering and
raising the arm has long been utilized. The dilatation of the veins
of the back of the hand when the hand is raised should disappear,
and they should practically collapse, in normal conditions, when the
hand is at the level of the apex of the heart. When the venous
pressure is increased, this collapse will not occur until the hand
is above the level of the heart. Oliver [Footnote: Oliver: Quart.
Med Jour., 1907, i, 59.] found that the venous pressure denoted by
the collapse of the veins may be shown approximately in millimeters
of mercury by multiplying by 2 each inch above the level of the
heart in which the veins collapse. When a normal person reclines
after standing there is a fall in venous pressure, and when he again
stands erect there is an increase in venous pressure.
Bailey [Footnote: Bailey: Am. Jour Med. Sc., May, 1911, p. 709.]
states that in interpreting pulsation in the peripheral veins, it
should not be forgotten that they may overlie pulsating arteries.
Pulsation in veins may be due also to an aneurysmal dilatation, or
to direct connection with an artery. As the etiology in many
instances of varicose veins is uncertain, he thinks that they may be
caused by incompetence of the right heart, more or less temporary
perhaps, from muscular exertion. This incompetence being frequently
repeated, peripheral veins may dilate. Moreover, the contraction of
the right heart may cause a wave in the veins of the extremities,
and he believes that incompetency of the tricuspid valve may be the
cause of varicosities in the veins of the extremities.