Replacing the HeartBy: Jennifer B.

How it all started…•Even in ancient times, people experimented with exchanging tissues from their own body or another person’s body to fix up an area.

•The idea came from the even older concept of agricultural transplantation. A plant could be dug up, and re-planted in a new area and continue to survive.

•Those who have heart disease and have little hope of surviving more than six months.

•Other requirements:

•Those between the ages of 13 and 50

•Those in relatively good health (other than their heart disease)

•Those who are mentally stable

•Those who are able to cooperate well with doctors and willing to follow a strict medical routine for the rest of their lives.

               

Who needs a new heart?

•The heart pumps over 300 quarts of blood an hour. Your heart will beat approximately 2,700,000,000 times in a lifetime. There are 59,951 miles of blood vessels in your body!

•It is a fact that the heart, when taken out of the body, will continue to beat. Even when cut into parts, the muscles in the heart will continue to contract.

•The human body contains up to ten pints of blood. Red blood cells are formed at a rate of 2 million per second.

What makes replacing the heart so difficult??

The Heart--Basics

• Structure:

– Made up of 4 chambers

• Two atria

• Two ventricles

– Valves present to prevent backflow of blood

• Job: Muscular pump that forces blood through vessels in order to reach the entire body

The Heart--Basics

Combines two basic systems to function:

–Mechanical

–Electrical

Cardiac Muscle

•Involuntary muscle, that differs from most other muscle types, which require stimulation by a motor nerve in order to contract.

•These muscles will continue to beat even out of the body as long as they are kept in an oxygenated nutrient solution.

Cardiac Muscle

• Intercalated discs are present, which are connections between two adjacent cardiac cells. These help multiple cardiac muscle cells contract rapidly as a unit.

• Contract more powerfully because they are stretched slightly. (Due to the filling of the ventricles, stretching beyond their normal resting capacity. )

How does it work?

The heart is made up of millions of cells.

Each cell has a membrane, and on each side of this membrane is a mix of positive and negative charges.

The Electric System

• The electrical system of the heart is comprised of several nodes and bundles which allow electrical currents to pass through.

• As a whole, it is mainly responsible for the heart’s pacing system, which regulates the blood flow throughout the body.

DiagramBeat originates in the sinoatrial node (the heart’s natural pacemaker)

The impulse spreads to the atria and through the heart wall to the apex, which signals the ventricles to contract.

Arrhythmias

• Occur when the heart’s rhythms are not in synch.

• Result of: sinus node dysfunction, atrioventricular (AV) block or intraventricular conduction delay

• Two different types:

– Bradycardia

– Tachycardia

Diagnoses

• Catheterizations

• EKG

Treatments

• Drug therapy

• Replace cells with genetically manufactured cardiac cells

• Remove blockage if present

• Pacemaker implantation

Artificial Pacemakers• Placed in pocket near shoulder

• May have 1 or 2 leads

• Help regulate slow pulse (bradycardia)

• 1/3 battery 2/3 computer

• Needs replacement about every 15 years

What they do• Sensor and record heart rate

• Give an impulse when the normal threshold is not reached

• Allow patients with arrhythmias to lead normal lives

Is it possible to make a kinetic pacemaker?

• Replace battery pack with kinetic energy source

• Put sensor in arm (or other place that moves constantly) connecting to pacemaker

• There have been experiments in the past.

Kinetic Energy• Kinetic Energy = the energy associated

with movement– Exists when an object has mass in motion

with some velocity

– KE = ½ (object mass) x (velocity²)

• There are several different forms:– Vibrational

– Rotational

– Translational

Benefits/DownfallsNo need to replace batteries

Patient is able to live a more normal life

Pacemaker could be made smaller

o Kinetic parts would also need replacement eventually

o The energy may not be able to transfer from the node in the arm to the pacemaker itself

Final Analysis

Is it really worthwhile to try to invent such a device?

I think that its worth a try, but if newer technology allows us to duplicate the natural heart cells, that would be our best shot.