Fibrillation and heart block are grave conditions when found in pregnancy, but disease of the mitral valve because of frequency is more important, and when compensation is unstable mitral lesions are dangerous. In mitral stenosis the enlarged uterus in the last months of gestation, by crowding the intestines and diaphragm, embarrasses the heart. As the diaphragm cannot descend well, the flow of blood out of the right ventricle is not aided by respiration as in normal conditions. Pressure on the abdominal veins increases the blood tension and throws greater work on the left ventricle. In the expulsive stage of labor there is danger of the right ventricle giving way under the added strain. In mitral regurgitation the left ventricle is dilated, and in pregnancy the regurgitation is increased by the peripheral resistance or obstruction. If the dilated ventricle is also hypertrophied it stands the strain much better. In the second stage of labor the danger is the same as in mitral stenosis. In disease of the aortic valve the strain of child-bearing is on the left ventricle, but patients in this condition undergo labor more successfully than do those with mitral disease. Labor in any cardiac disease requires close watching even when the compensation is good. There is always a possibility of collapse in the third stage or during the puerperium. The obstetrician must stay by the bedside, and he is to have everything ready for a sudden emergency, which is likely to result in death if not instantly met. All the instruments for operative delivery are to be kept sterilized and ready for immediate use. When symptoms of imminent collapse appear, delivery is to be done at once. If a cardiopath collapses in the early stages of gestation, before the child is viable, the rule explained in the chapter on Abortion holds--the child may not be killed by removal to save the woman's life. Jaschke,[135] in his consideration of 1548 pregnant cardiopaths, found that seven-eighths went to term, and that the women were prematurely delivered in only about 9 per cent. of the total number of cases. Therapeutic interruption of pregnancy was necessary in only about 1 per cent. The high mortality reported by many good obstetricians is a proof that the treatment of cardiac conditions requires an experience in clinical medicine and a skill lacking, as a rule, in specialists who are not internists. [135] _Loc. cit._ A combined mitral and aortic disease with great enlargement of the heart, heaving of the chest wall, and some protrusion makes pregnancy very dangerous. Osler thinks mitral insufficiency in itself not very dangerous. He had one patient with such a condition, a loud apex systolic murmur, and some enlargement, who bore nine children and lived to past sixty years of age. Mitral stenosis is not so favorable, but even in extreme stenosis some women bear several children without collapse. CHAPTER XV HYPEREMESIS GRAVIDARUM