The heart enlarges by about 12% between early and late pregnancy.Distension of the heart chambers is due partly to increasing myometrical hypertrophy ,but mostly to increased diastolic filling in parallel with the increasing blood volume.Echocardiology studies of cardiac enlargement in pregnancy show that wall thickness increases very little .cardiac enlargement does not appears to be associated with reduced myocardical efficiency as proportion of blood ejected during systole increases during early pregnancy.The improvement in myocardial contractility is thought to be due to lengthening of muscle fibers or to reduction in after load associated with the marked peripheral vasodilation that is characteristics of pregnancy .During the late pregnancy the degree of vasodilution decrease and the ejection fraction also diminishes..
The growing uterus elevates the diaphragm,the great vessels are unfolded and the heart is correspondingly displaced upwards,with the apex moved laterally to the left by about 15 degree.This can give an exaggerated impression of cardiac enlargement ,and the accounts for the left axial deviation seen on the electrocardiogram in pregnancy and for the apex beat appearing in the fourth rather than the fifth inter costal space.This electrocardiogram and radiography changes are similar to those seen in ischaemic heart diseases but are considered normal pregnancy.The ECG also often reveals a Q wave and inverted T wave in lead three,which should not be misconstructed as suggesting pulmonary embolus.Atrial or venticular extrasystoles are frequent and there is increased susceptibility to superventicular tachycardia.
By mid-pregnancy more than 90% of women develop an ejection systolic murmur,which lasts until first week postpartum.If unaccompanied by any other abnormalities it reflects the increased stroke output .Twenty percent develop a transient diastolic murmur and 10% develop continuous murmurs,heard over the base of the heart,owing to increased mammary blood flow.The increase in cardiac output ranges from 35 to 50% in pregnancies,from an average of 5 L/min before pregnancy to approximately 7 L/min by the 20th week after the changes are less dramatic.
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| Author: RoseNinja 13 Sep 2009 | Member Level: Gold Points : 1 |
Hi,
Hearts is one of sensitive part of our body,we need to keep our heart always safe.Pregnancy women's needs to give more importance to his because of his babies.
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| Author: Vilas 13 Sep 2009 | Member Level: Diamond Points : 1 |
Dear Rose,
Great work done nice article.
i appreciate your knowledge.
with best regards
vilas
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