clinical presentation of congenital heartdisease in the first week of life: congestive heart failure, by dr. michael freed. my name is michael freed and i'm a pediatriccardiologist at boston children's hospital and at harvard medical school. and i want to spend a little time today talkingabout congenital heart disease in the newborn period. introduction. children come in in the first week of life. they present in one of four ways.
with a heart murmur, with an arrhythmia, congestiveheart failure, or with cyanosis. so let's talk about congestive heart failure. congestive heart failure is an inability ofthe heart to do the work that's required, and the signs and symptoms that come becauseof that inability. there are two conceptual reasons why you mighthave difficulty. the first is that there is something wrongwith the heart muscle. you have a normal amount of work. but somehow the muscle just isn't strong enoughto do the work. the second is that you have a normal muscle,but you've put too much of a workload on it.
so if there was a weight on the table in frontof me, if there was a 5 pound weight and i couldn't do it, there's something wrong withme. if there's 1,000 pound weight, i just can'tdo a 1,000 pound weight. if you looked around our ward, i think youwould say that the structural problem, too much work with normal muscle is much morecommon. i'm not so sure that's the case. fetal development. i think that almost all of these are geneticdefects. and i suspect there are just as many geneticdefects in the mitochondria and energy transport
systems as there are causing structural heartdisease, but we just don't see them. where are they? well, i think they don't survive fetal life. i think that you can be born without kidneys,you can be born without lungs, you can be born without a large part of your brain. but once you have an embryo that's more thanfour cells thick, you need some way of getting nutrients inside to the cells and get wasteproducts out. so once an embryo is more than four cellsthick, you need some type of circulatory system. and in fact, in the human, there's a primitivestraight tube that develops by 27 days after
conception that's actually doing the work. and if there's something wrong with that tube,if there's something wrong with the muscle, they just don't survive fetal life. so i think a lot of first trimester abortionsmay very well be heart muscle problems that we're not seeing. and the rest of fetal life selects out forthose, leaving just the ones with normal muscles, but structural problems. and the corollary to that is that the thingsthat we're seeing at birth are in fact things that work in utero.
otherwise, they wouldn't survive fetal life. and what happens is that i think that thefact that the circulation is arranged in parallel rather than series allows a whole group ofvery complicated diseases that work in the newborn period, but once you go into thatin the series circulation, don't work after you're born. so i think this presentation of babies inthe first week of life are kids that worked in utero, but don't work when they're born. and i think there's a comparable group thatdoesn't work in utero that we're not seeing, and a lot of those have muscle problems.
structural heart disease. so if we have a baby with congestive heartfailure-- he doesn't have a muscle problem, he's got some structural problem, too muchwork for a normal muscle. and remember, we said the work of the heartis pressure and volume, so there must be either too much pressure work or too much volumework. if you look at the first month of life, ithink that most kids who come in would be too much volume work. ventricular septal defects, single ventricleswithout pulmonary stenosis, truncus arteriosus, the whole variety of things.
but we don't see those in the first week oflife. in the first week of life the pulmonary vascularresistance is still quite high. and it prevents enough of a left-to-rightshunt through the vsd, or the single ventricle, or the truncus to give enough of a volumeoverload to cause congestive heart failure. so if our talk is heart failure in the firstweek of life, which is what we've started the premise, then we're dealing not with muscledisease, not with volume overload, but just pressure overload lesions. and if you look at the pressure overload lesions,aortic stenosis, pulmonary stenosis, coarctation, and hypoplastic left heart syndrome.
and i'm going to make it even easier. pulmonary stenosis doesn't fit here. if we're talking about heart failure, tachypnea,tachycardia, not feeding very well, sweating-- that's not the way pulmonary stenosis presents. if you look at pulmonary stenosis, these kidshave severe right ventricular outflow tract obstruction. the right ventricle has to generate a higherpressure to pump blood out. and if it starts having difficulty generatingthat higher pressure, by starling's law, it increases preload.
if you increase the preload in the ventricle,the atrial pressure goes up. and in the newborn period, if the right atrialpressure exceeds the left atrial pressure, you start shunting right-to-left and you endup with cyanosis. so kids with severe right ventricular outflowtract obstruction from pulmonary stenosis present with cyanosis, not with congestiveheart failure. so now we're essentially down to three diseasesin our differential diagnosis of heart failure in the newborn period. and how can we tell these apart? well, coarctation-- now, the difference inpulses or blood pressure should work.
that is, before the ductus closes they'renot sick. but if these kids are sick, the ductus musthave closed and now they must have a pressure gradient. so just feeling pulses or measuring pre- andpost-ductal blood pressures should diagnose coarctation for you. in neonates with coarctation of the aorta,the strength of the pulses in the lower extremity will be reduced or absent in comparison tothe pulses in the upper extremity. pre- and post-ductal blood pressure examinationwill reveal a discrepancy between the right arm-- which is pre-ductal-- and the leg--which is post-ductal-- blood pressures, with
a higher systolic blood pressure in the rightarm when compared to the legs. typically, a discrepancy of greater than 20millimeters of mercury in the systolic pressure measurement is considered significant andshould prompt further workup for coarctation. to separate out aortic stenosis from hypoplasticleft heart syndrome get an electrocardiogram. these kids have lvh. these kids have no lv. and that's the differential diagnosis of heartfailure in the newborn. this concludes our video on clinical presentationof congenital heart disease in the first week of life: congestive heart failure.
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