Aortic valvular disease more frequently than mitral is of non-rheumatic origin; it is slower in its development, and is more commonly met with in advanced life.
SYMPTOMS.—The subjective symptoms of obstruction at the aortic orifice are not usually well marked. Extensive aortic stenosis is not incompatible with a state of comparative good health. As the obstruction to the outflow of blood from the ventricle increases, compensatory ventricular hypertrophy enables the heart to fill the arterial system and relieve the pulmonary pressure. As soon as the ventricular hypertrophy no longer compensates for the obstruction, the arteries are inadequately filled; the left auricle cannot empty itself into the left ventricle, and hence the pulmonary vessels are abnormally full, as is also the entire venous system. The scanty arterial supply gives the pallor to the face which so frequently accompanies this condition, and syncope is liable to occur as a result of partial cerebral anæmia.
These are late effects, and in many cases do not make their appearance until the mitral valve is secondarily involved. The pulse in aortic stenosis is normal in frequency, diminished in volume and power, usually regular in rhythm, though it may be intermittent, and is compressible and jerky in character.
As a general rule, in aortic stenosis signs of arterial anæmia precede evidences of venous engorgement. The obstruction to the exit of blood is shown in the sphygmographic tracing by a slanting or oblique up-stroke, as seen in the accompanying tracing, or, as Mahomed says, "the influence of percussion is lost." Tracings of the pulse in aortic stenosis sometimes show considerable separation between the percussion and the tidal waves. In some rare instances the pulse is slowed. There may be slight palpitation, and pain in the chest may sometimes occur in paroxysms; but pain in the chest is far more common in regurgitation than in obstruction. Aortic obstruction is more frequently connected with cerebral embolism than any other valvular lesion.
| FIG. 41. |
| Aortic Obstruction (after Foster). |
The left middle cerebral artery is the most common seat of aortic cardiac emboli. The left lower limb is more subject to embolism from aortic valvular disease than the right. The splenic and renal vessels are also the frequent seat of such emboli. Sometimes embolism is due to small auricular or ventricular clots that form behind the obstruction. Such clots have occluded the aortic orifice and caused sudden death.7
7 Pathological Transactions, vol. ix. p. 91.
PHYSICAL SIGNS.—The physical signs of aortic obstruction are generally distinctive and easily appreciated.
Inspection.—The visible area of the cardiac impulse is abnormally increased. Very extensive increase in the area of impulse is frequently accompanied by a lifting of the chest-wall over the heart.