Page 156 - 84 human physiolofy part-1

Chapter 8

• QRS is the ventricular depolarization
• T is the ventricular repolarization

Extrinsic Control of Heartbeat

Autonomic system with two subdivisions: the sympathetic division and the parasympathetic
division. Hormonal control of blood pressure

• Epinephrine
• Norepinephrine
• ANP : Atrial natriuretic peptide
• ADH: Antidiuretic hormone
• Renin-Angiotension system

Case Study

An example of the ever expanding technology for the heart is best described in this story:

In 1955, when I was five years old, I first learned by my family physician that I had a heart
murmur and that it would eventually need attention. By the time I was 15 in 1965, I had two cardiac
catherizations at Rhode Island Hospital. The tests were inconclusive and I was told to go on with my
life and wait and see if I had a problem.

It wasn't until 1975 that I was told by my family physician that I should have my heart checked
again. Dr. David Kitzes of Mariam Hospital performed another catherization. This time, unlike the
others, I was told that because of new machine technology, Dr. Kitzes found that I had aortic stenosis,
which is a narrowing of the valve passage by build-up of plaque due to the valve being malformed at
birth. Dr. Kitzes informed me that I could lead a normal life until I was in my fifties or sixties before I
would need corrective surgery.

In 1996, I had an echocardiogram and it was determined that my heart was enlarged. My family
physician said that I should see a cardiologist. I down played the visit as not being serious after hearing
the same thing many times. This time I entered the office of Jon Lambrecht, I had never met him
before. Within a few minutes my whole life was turned around. After asking me about my symptoms,
which were fatigue, weakness, asthmatic symptoms, as well as ashen skin color and dizziness, he
informed me of how serious my condition was and the only salvation was immediate open-heart
surgery to replace the aortic valve. I began to cry as I thought my life was over. Dr. Lambrecht studied
my reaction and told me that this condition is repairable and that I don't have a terminal illness. I didn't
have a lot of time to think about it. Within 10 days from that visit, I was the recipient of a Meditronic
Hall Prosthetic heart valve. The operation was performed by Dr. Robert Indeglia at Miriam Hospital in
Providence, R.I. on March 20th, 1996.

It has been almost 3 years since the surgery and I am doing better than I could have expected. In
1977 my son Kevin was born with Hypoplastic Left-heart Syndrome and only lived for 2 days because
heart surgery wasn't performed like today. I am thankful that I lived at a time when medical technology
paved the way for a second chance because of my new aortic heart valve. Our goal in this chapter is to
take you by the hand and lead you through each part of the cardiovascular system, so that you too may

156 | Human Physiology