Frequently
Asked Questions
The following are typical questions asked about the heart and things related
to it. These questions are good examples of how complicated the human body is.
These questions and answers are good examples of why it is important to take
care of your body and subscribe to good nutrition to help maintain the astonishing
purposes and data that makes up the human anatomy.
What is the role of the heart and the blood?
The heart is the pump that circulates the blood which carries oxygen to all
your body organs and systems. The blood travels through the tunnel like interstate
system of arteries, veins and capillaries The capillaries are minute blood vessels
(small as a strand of human hair) that connect arterioles and venules. These
blood vessels form an intricate network throughout the body for the interchange
of various substances, such as oxygen (O2) and carbon dioxide (CO2) between
blood and tissue cells that deliver the vital blood to systems that make our
body work and maintain life.
This is why we should feed our bodies with nutrients instead of junk food and fatty foods. Think of these foods as "gunk" that stops up all these tiny systems that hamper the delivery and extraction of the O2 and CO2.
How
does the blood system respond to exercise?
Blood Vessels go through rapid changes when you are exercising. Exercise stimulates
chemical and nerve signals, the artery walls leading to your muscles being exercised
will relax, causing the arteries to widen. The peripheral veins will constrict,
forcing more blood into the central circulation. The smaller arterioles leading
to your exercising muscle fibers will widen. The millions of dormant capillaries
open up (these feed blood directly to the muscle fibers)..
How
is pulse rate a good measure of physical conditioning?
Each time your heart beats it forces a surge of blood through your arteries.
This surge is called your pulse. The speed at which your heart beats changes
many times every day. You can measure the speed by taking your pulse. Exercise
will change your pulse rate from what it is when sitting or relaxing. The regulation
of pulse is a complex system influenced by several factors, one of these is
physical conditioning. A short recovery time and a low resting pulse are both
signs of a well-conditioned system.
What
is meant by "heart beat?"
The heart is said to beat when the pumping of blood occurs. Practice counting
your heart beats until you are sure you can count accurately. Count the number
of beats you feel in ten seconds and write it down.
What
are arteries?
Vessels that carry blood from the heart are called arteries. For example - the
arteries on your wrists and on the side of your neck are near the surface of
the skin. At these points you can feel the surge from your heart.
What
is meant by "Pulse?"
Each time your heart beats it forces a surge of blood through your arteries.
This surge of blood is called your pulse. The SPEED at which your heart beats
changes many times during the day. You can measure this speed by taking your
pulse. The pulse rate is the number of times your heart beats in one minute.
If you want to calculate your pulse per minute, take the number of beats in
ten seconds and multiply it by six. This tells you how many times your heart
beats in 60 seconds, or one minute. You can calculate this while doing different
activities to see how activities can change your pulse rate. Typically, sleep
or resting quietly should be the lowest rate while doing hard work or exercising
will be the high test rate.
What
is the average pulse rate?
While at rest, an average pulse rate is 70 - 72 beats per minute for adult males.
While at rest, an average pulse rate is 78 - 82 beats per minute for adult females.
These rates can increase (as much as 200 beats/minute) during vigorous exercise.
How
much water does a human body contain?
Average adult contains 79 pints (45 liters) of water - about 65% of their body
weight.
How
much blood is in the human body?
8 pints (4.5 liters) passes through the lungs about once a minute.
How
large is the heart?
Your heart is about the size of your fist.
How
much blood does the heart pump over a life time?
The heart will pump over 100 million gallons of blood over a lifetime.
How
many heart beats will occur during a a human life span?
The heart will beat more than 2,000,000,000 (2 billion) times.
How
many blood vessels are in the human body?
60,000 miles plus of blood vessels.
What
is an ICD?
An ICD is a downsized,
automatic version of an external defibrillator like those used by clinicians
and paramedics to convert the heart back to a normal rhythm. An ICD is about
the size of stopwatch and is implanted under the skin near the collarbone. The
device connects to insulated wires called leads, which in turn connect to the
heart. ICDs deliver shocks and other electrical therapies to the ventricles
to stop ventricular tachyarrhythmias.
What
is ventricular tachyarrhythmias?
In cardiomyopathy, the heart is typically enlarged and its muscle tissue
does not contract effectively. The heart may gradually weaken over time, leaving
the patient susceptible to ventricular tachyarrhythmias, dangerously fast heart
rhythms originating in the ventricles, the heart's lower chambers. Ventricular
tachyarrhythmias include ventricular tachycardia (VT) and ventricular fibrillation
(VF), which are common contributors to sudden cardiac death, the number one
cause of cardiac death in the United States. Sudden cardiac death accounts for
approximately 300,000 deaths annually.
What
is Syncope?
Syncope is a sudden and temporary loss of consciousness, or fainting. Most people
pass out at least once in their life. It is a common symptom and often does
not indicate a serious medical problem. However, sometimes syncope idicates
a dangerous or even life-threatening condition, so when syncope occurs it is
important to see your doctor to figure out the cause.
What
causes Syncope?
The causes can be grouped into four major categories:
1. neurologic syncope (deals with the nervous system and disorders affecting
it)
2. metabolic syncope (relating to, or resulting from metabolism)
3. vasomotor syncope (relating to, causing, or regulating constriction or dilation
of blood vessels)
4. cardiac syncope (relating to the heart - can be fatal)
Of these 4 categories, only cardiac syncope commonly leads to
sudden death. Since I am a cardiologist I will talk about this area only.
There are two major varieties of cardiac syncope:
1. obstructive cardiac lesions
2. cardiac arrhythmias.
Obstructive cardiac lesions:
Several heart disorders can result in an obstruction of blood flow through the
heart. They include
~ obstructed heart valves (aortic stenosis and mitral stenosis are the most
common examples;
~ obstructed blood vessels (such as a massive pulmonary embolus;
~ cardiac tumors (such as an atrial myxoma, a benign tumor that can obstruct
the mitral valve).
Most of these lesions are readily apparent to a physician taking a careful medical history and doing a careful cardiac exam. They can be confirmed by performing a simple echocardiogram.
Syncope-producing
cardiac arrhythmias:
There are two major categories of life-threatening, syncope-producing cardiac
arrhythmias:
~ bradycardias (slow heart rhythms that can be treated by inserting a cardiac
pacemaker.
~Tachycardias (ventricular tachycardias (VT), supraventricular tachycardias
(SVT)
With rare exceptions, SVT does not cause syncope nor does it cause sudden death. (The most common exception to this rule is in patients with Wolff-Parkinson-White syndrome (W-P-W), in which, rarely, SVT can degenerate into the much more dangerous ventricular variety of tachycardia.)
Ventricular tachycardia, on the other hand, commonly causes sudden death. And unfortunately, ventricular tachycardia is common in people who have underlying heart disease, and is commonly overlooked by doctors. If it is missed once, neither the doctor nor the patient are likely to get a second chance to undo the error.
The key to diagnosing ventricular tachycardia is to understand that this arrhythmia is extremely rare in individuals with completely normal hearts, while it is very common in patients who have heart disease. Thus, a major consideration in evaluating a patient with syncope of unknown cause is to decide whether a patient has underlying heart disease (especially ventricular muscle damage due to coronary artery disease, or to a viral infection of the heart muscle). If the ventricular muscle is normal, then the possibility of ventricular tachycardia as a cause of syncope can be largely dismissed. There can be rare exceptions to this “rule."
On the other hand, if the ventricles are abnormal, the doctor’s focus must shift immediately from merely preventing syncope to preventing sudden death. The patient should be immediately hospitalized and placed on a cardiac monitor, and must remain monitored until either ventricular tachycardia is ruled out, or definitive therapy to protect against ventricular tachycardia is instituted. In general, an electrophysiology study is done to assess the heart’s electrical system, and evaluate the patient’s propensity for developing ventricular tachycardia. If the electrophysiology study documents ventricular tachycardia, the patient should receive an implantable defibrillator (an pacemaker-like device that monitors the heart rhythm continuously, and delivers therapy automatically if a dangerous heart rhythm occurs).
Because of the high price
that may be paid if ventricular tachycardia is missed, the doctor’s index
of suspicion for this diagnosis must be high. Any patient with a history of
coronary artery disease, or even with significant risk factors for coronary
artery disease, needs to be evaluated. Indeed, if a careful medical history
and physical examination do not reveal any other likely cause of syncope, a
cardiac evaluation should be undertaken.
What is heart block?
A condition in which faulty transmission of the impulses that control the heartbeat
results in a lack of coordination in the contraction of the atria and ventricles
of the heart. The atria is a bodily cavity or chamber, especially either of
the upper chambers of the heart that receives blood from the veins and forces
it into a ventricle. Ventricles are the chambers on the left side of the heart
that receives arterial blood from the left atrium and contracts to force it
into the aorta and the chamber on the right side of the heart that receives
venous blood from the right atrium and forces it into the pulmonary artery.