There may be =dilatation= with thickening of the walls, and dilatation
with thinning of the walls, or they may be normal. It may be produced
by impaired nutrition of the cardiac muscle or increased endocardial
tension. More frequently the two conditions act jointly, although they
may act singly. Impaired nutrition of the cardiac muscle may diminish
the resisting power and thus cause dilatation. Weakening of the cardiac
walls may occur in scarlatina, typhoid, typhus, rheumatic fever, etc.
It is met with in chlorosis, anemia and leukemia. Increased endocardial
tension occurs in sudden, extreme exertions and in valvular diseases.
A normal heart through excessive exertion is rarely if ever dilated.
The important causes are considered under hypertrophy. Both impaired
nutrition and increased endocardial tension are influenced directly by
the extent and severity of the osteopathic lesion. This point has been
considered under chronic endocarditis.
=Pathologically=, the right side is more commonly affected than the
left. In advanced aortic incompetency, all the divisions may be
dilated. When one ventricle alone is dilated the septum may be seen
to bulge. In extensive dilatation, the auriculo-ventricular rings
are often dilated. Other orifices may also be dilated. The condition
is often associated with =hypertrophy= and =fatty degeneration=. The
muscle may be normal in appearance. The endocardium is often opaque,
and roughened in patches. There is degeneration of the ganglia of the
heart.
=Symptoms.=—Dilatation causes weakness of the walls of the heart, but
as long as the hypertrophied walls can compensate, no symptoms result.
When the hypertrophy weakens, greater dilatation occurs and symptoms
of venous stasis appear, as dropsy, feeble irregular pulse, dyspnea,
cough and scanty urine. In some instances there may be brief precordial
distress, faintness or palpitation.
=Physical Signs.=—On =inspection= the apex-beat is diffuse and feeble,
or it may not exist. As observed by Walsh, the impulse may be visible
and yet not palpable. =Palpation=—the impulse is diffuse, feeble and
fluttering. The pulse is small, rapid and irregular, rarely is it slow.
=Percussion=—the area of lateral dullness is increased to the right.
There is increase in the dullness downward to the sixth interspace and
upward to the second rib in many cases. =Auscultation=—the sounds are
weak and sharp. The first sound is shorter, lacks its muscular element
and becomes more like the second. The sounds are obscured, the cardiac
murmurs are present. In many cases the characteristic gallop rhythm is
present. When the right heart is chiefly dilated, the true apex-beat
cannot be felt, while an impulse may be felt below the xiphoid
cartilage, and a wavy impulse is seen in the fourth, fifth and sixth
interspaces to the left of the sternum.
=Diagnosis.=—When a clear history can be obtained, together with the
characteristic features, the diagnosis can be readily made. =Prognosis=
depends upon the cause.
=Treatment.=—The treatment of dilatation is that of valvular heart
disease. It is important that the patient should have plenty of rest,
suitable food and regulated exercises.
In acute dilatation absolute rest is necessary. Limit the fluid intake,
and open the bowels thoroughly. In serious cases, bleeding, a pint or
more, should be considered.