Anyone Who Had A Heart: A Case Study in Physiology 1

Part I—Prenatal Visit


It had been a hectic day for the doctor, and his last patient was on
time for her appointment.

“Hi. Sis.”

“Hi, Jim. How’s my kid brother?”

“Tired—how’s the first-time mom? Have you stopped work yet?”

“Come on, Jim, I’m a career woman. The chemical industry needs me.
It’s tough to go cold turkey. When Dave and I decided to have a family,
we agreed that I should work as long as I could.”

“You’re the size of a house, Jen. You’re 37 years old, you have twins
that are 28 weeks, and I really would like you to carry them as long as
you can.”

“Oh, oh, here comes the lecture again. I know you didn’t like the
fertility procedure we did, but I just couldn’t get pregnant. Anyway, as
you so tactfully pointed out, doctor, I am not getting any
younger. Look at it this way; we’re having our family all at once.”

There was a knock at the door and the nurse entered.

“How did the ultrasound go?”

“It’s like Times Square,” replied the nurse. “Arms and legs
everywhere—it’s almost impossible to see anything, and those kids are so
active. I just hope they slow down after they’re born, otherwise you’ll
get no rest until they go to college. It’s crazy in there, with two
hearts beating. And with yours in the background, it’s tough to isolate
one. As best as I can tell, the rates are around 130 to 160 beats a
minute.”

“OK, well let’s see if the expert can hear anything.”

Both women glared at the doctor.

“Do you need the crane or can you get up on the table by yourself?”

Jen looked at the nurse and said, “Is he like to this to all his
patients?”

“No comment; I need this job.”

They laughed and Jim went to work. Moving the head of his stethoscope
to different locations, he tried to isolate the sounds from one heart.
His expression changed as he listened intently. Jen began to worry as
her brother took longer than usual with his stethoscope.

“Is everything OK?” she asked.

Jim looked concerned. He was reluctant to tell his sister that he
thought he had heard a heart murmur. Like his nurse had said, it was
difficult to hear just one heart. He didn’t want to alarm his sister, so
he made a joke of the situation.

“Must be a girl in there, she won’t stop talking. I think she said
something about not leaving the hospital in just any outfit.”

Jen went to hit her brother, but he easily evaded the playful smack.

“It’s tough to predict when the babies will arrive, so I think you
should start coming to see me every week, Jen.”

“Is there a problem? You did all of the tests, and you said that I’m
not diabetic. The alpha-fetoprotein levels indicate no neural tube
defects, and that horrible amniocentesis procedure showed no birth
defects or Rhesus problems.”

“It’s OK, Sis. It’s quite normal for women who are close to delivery
to visit their OB-GYN every week. It’s tough to predict delivery with
multiple births, because they rarely go full term. So, to be on the safe
side, let’s get together every week from now on. In that way I can see
your lovely smiling face more often.”

Jen scowled at her brother.

“For once in your life, do what I ask,” Jim said. “And bring Dave
with you next time.”

A little later, as Jim was finishing his paper work for the day, the
nurse returned to his office.

“Everything OK with Jen?”

“I can’t stop thinking about that vague sound I heard. It sounded
like a heart murmur, but it’s so tough to single out with two kids in
there.”

“I thought I heard it too. The babies seem active and are about the
same size. No history of birth heart defects in either family, but I
guess you never know with twins in an older mom.”

“My thoughts exactly. I don’t want to worry her because you know how
hyper she can be. I guess we’ll need to keep a close eye on her, and on
my nephew and niece.”

“Does Jen know the sexes?”

“She and Dave don’t want to know. They want to be surprised.”


Questions

1. Draw a diagram of the heart of a human adult. Show the circulation
   of the blood through the heart and to and from the body and the lungs.
   
2. Draw a diagram of the heart of a human fetus. Show the
   circulation of the blood through the heart and to and from the body and
   the lungs.
   
3. What are the major structural differences between the
   fetal and the adult human heart? Draw and label these differences on
   your diagram of the fetal heart. How do these structures alter the
   circulation of blood?
   
4. Why is the pulmonary circulation reduced in the human
   fetus?
   
5. Are heart rates of 130 to 160 normal in a human fetus?