Stethoscopes

Rene Laennec to David Littmann

The history of medicine is filled with tales of superstition, omens, rituals and myths.

William Harvey was the first to describe the functions of the heart and lungs in transporting blood through the body.

This is the story of the evolution of the stethoscope.

 

Rene Laennec, a French physicist, rolled up a sheet of paper and invented a stethoscope.

 

David Littmann, the son of Russian immigrants, invented the modern stethoscope in his basement.

 

This is their story.

 

Cardiovascular System

The hemoglobin molecule is the primary transporter of oxygen

Heart

The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs.

Coronary circulation system

Provides blood supply to the myocardium (the heart muscle). It arises from the aorta by the left and right coronary arteries, and after nourishing the myocardium, blood returns through the coronary veins into the coronary sinus and into the right atrium. Back flow of blood through its opening during atrial systole is prevented by the thebesian valve. The smallest cardiac veins drain directly into the heart chambers.

Pulmonary circulation system

Oxygen deprived blood from the superior and inferior vena cava, enters the right atrium of the heart and flows through the tricuspid valve into the right ventricle, from which it is then pumped through the pulmonary semilunar valve into the pulmonary artery to the lungs. Gas exchange occurs in the lungs, whereby carbon dioxide is released from the blood, and oxygen is absorbed. The pulmonary vein returns the now oxygen-rich blood to the left atrium.

Systemic circulation

Oxygenated blood is transported away from the heart through the aorta from the left ventricle to the rest of the body, and then oxygen-depleted blood is returned back to the heart. Systemic circulation is much longer than pulmonary circulation, transporting blood to every part of the body.

Oxygen transportation

About 98.5% of the oxygen in a sample of arterial blood is chemically combined with hemoglobin molecules. About 1.5% is physically dissolved in the other blood liquids and not connected to hemoglobin. The hemoglobin molecule is the primary transporter of oxygen.

The Human Heart

The heart is a hollow muscular organ

Muscle:The heart is a hollow muscular organ that pumps blood throughout the blood vessels to various parts of the body by rhythmic contractions. It is found in all animals with a circulatory system, including the vertebrates.

Chambers: The human heart has four chambers. The atria are the receiving chambers and the ventricles are the discharging chambers. During each cardiac cycle, the atria contract first, forcing blood into their respective ventricles, then the ventricles contract, forcing blood out of the heart.

Cycles: Deoxygenated blood from the body flows via the vena cava into the right atrium, which pumps it through the tricuspid valve into the right ventricle, whose subsequent contraction forces it out through the pulmonary valve into the pulmonary arteries leading to the lungs.

Meanwhile, oxygenated blood returns from the lungs via the pulmonary veins into the left atrium, which pumps it through the mitral valve into the left ventricle, whose contractions force it out through the aortic valve to the aorta.

Ventricles

Right Ventricle receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve.

Left Ventricle receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.

Atrium

Right Atrium receives deoxygenated blood from veins, and pumps it into the right ventricle through the tricuspid valve.

Left Atrium receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.

Arteries

Aorta is the main artery, which distributes oxygenated blood to all parts of the body.

Pulmonary artery carries deoxygenated blood from the heart to the lungs. 

Veins

Superior vena cava carries deoxygenated blood from the upper half of the body to the right atrium.

Inferior vena cava is the large vein that carries deoxygenated blood from the lower half of the body into the right atrium.

Lungs

oxygen into the bloodstream, carbon dioxide into the atmosphere

Oxygen:

 In mammals, the two lungs are located near the backbone on either side of the heart. Their principal function is to transport oxygen from the atmosphere into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere. A large surface area is needed for this exchange of gases that is accomplished by specialized cells that form tiny, thin-walled air sacs called alveoli.

Breathing is largely driven by the muscular diaphragm at the bottom of the thorax.

Alveoli:

Air enters through the oral and nasal cavities; it flows through the pharynx, then the larynx and into the trachea, which branches out into the main bronchi and then subsequent divisions until the alveoli are reached. These alveoli are where the gas exchange of carbon dioxide and oxygen takes place.

The lungs of mammals have a soft, sponge like texture and are honeycombed with epithelium.

In addition to respiratory functions, the lungs also:

·        Alter the pH of blood.

·        Filter out small blood clots formed in veins.

·        Filter out gas micro-bubbles such as those created during decompression after underwater diving.

·        Influence the concentration of some biologic substances and drugs used in medicine in blood.

·        Convert angiotensin I to angiotensin II by the action of angiotensin-converting enzyme.

·        May serve as a layer of soft, shock-absorbent protection for the heart, which the lungs flank and nearly enclose.

·        Immunoglobulin-A is secreted in the bronchial secretion and protects against respiratory infections.

·        Maintain sterility by producing mucus containing antimicrobial compounds.

·        Move up towards the pharynx dust particles and bacteria, in inhaled air, that are caught in mucous layers.

·        Provide airflow for the creation of vocal sounds.

·        Serve as a reservoir of blood in the body.

The Human Heart

starts beating at four weeks in the womb

London Olympics

1.     It is a muscle.

2.     It is the size of a fist and weighs around eleven ounces.

3.     It starts beating at four weeks in the womb.

4.     The maximum heartbeat for athletes may be 220 beats per minute.

5.     Resting heartbeat for cross-country skiers may be 35 beats per minute.

6.     Marathon runners, bicyclists, and cross country skiers can maintain a rate of 170 beats per minute for more than two hours.

7.     Typical heart beats in a lifetime — 2.5 billion.

8.     Pumps 1 .5 million gallons of blood in a lifetime.

9.     It is in the middle of the chest cavity — not on the left.

10.  Blood takes about 20 seconds to circulate.

11.  The system of blood vessels — arteries, veins and capillaries — is over 60,000 miles long.

Hippocrates

”The father of western medicine

Hippocrates

(c.460 – c.370 BCE) an ancient Greek physician of the Age of Pericles, is known as the father of western medicine.

Hippocrates is the ideal ancient physician. He promoted the logical and systematic study of clinical medicine and laid down the rules of practice for physicians through the Hippocratic Corpus and other works. He formulated the Hippocratic Oath and laws that are the guide for ethical good medical standards. These oaths are traditionally taken by medical graduates about to enter medical practice.

Rod of Asclepius

The Rod of Asclepius is named after the god Asclepius, associated with healing and medicinal arts in Greek mythology.  In honor of Asclepius, a non-venomous snake was often used in healing rituals.  The patient would report to a priest dreams or visions after spending a night in the holiest part of a sanctuary.  The priest would interpret the dreams and prescribe therapy. Some healing temples also used sacred dogs to lick the wounds of sick petitioners.

The serpent symbolizes rejuvenation because it sheds and then grows new skin. The serpent shows that the physician deals with life and death, sickness and health. Medical science holds the promise of renewal after illnesses.  The serpent is a sign of the physician’s concentration; the staff is a symbol of support.

   

Confusion with the caduceus

The caduceus is the staff carried by Hermes in Greek mythology.  Often the caduceus, with its two snakes and wings, is used as a symbol of medicine instead of the correct Rod of Asclepius, with only a single snake.  Most commercial healthcare organizations use the Caduceus symbol - the visual impact has better marketing potential.

“As god, Hermes was the patron of commerce and the fat purse:  his silver-tongued eloquence could always make the worse appear the better cause.” -— Stuart L. Tyson, "The Caduceus", in The Scientific Monthly.

Hippocratic Oath

Never do harm to anyone

I swear by Apollo, the healer, Asclepius, Hygeia, and Panacea, and I take to witness all the gods, all the goddesses, to keep according to my ability and my judgment, the following Oath and agreement:

To consider dear to me, as my parents, him who taught me this art; to live in common with him and, if necessary, to share my goods with him; To look upon his children as my own brothers, to teach them this art; and that by my teaching, I will impart a knowledge of this art to my own sons, and to my teacher's sons, and to disciples bound by an indenture and oath according to the medical laws, and no others.

I will prescribe regimens for the good of my patients according to my ability and my judgment and never do harm to anyone.

I will give no deadly medicine to any one if asked, nor suggest any such counsel; and similarly I will not give a woman a pessary to cause an abortion.

But I will preserve the purity of my life and my arts.

I will not cut for stone, even for patients in whom the disease is manifest; I will leave this operation to be performed by practitioners, specialists in this art.

In every house where I come I will enter only for the good of my patients, keeping myself far from all intentional ill-doing and all seduction and especially from the pleasures of love with women or men, be they free or slaves.

All that may come to my knowledge in the exercise of my profession or in daily commerce with men, which ought not to be spread abroad, I will keep secret and will never reveal.

If I keep this oath faithfully, may I enjoy my life and practice my art, respected by all humanity and in all times; but if I swerve from it or violate it, may the reverse be my life.

History of cardiology

Servetus was burned at the stake

Humorism

Ancient Greek and Roman physicians believed that four distinct bodily fluids in a person directly influenced their temperament and health. The four humors of Hippocratic medicine are black bile, yellow bile, phlegm, and blood, and each corresponds to one of the traditional four temperaments: Chloric, Sanguine, Melancholic, Phlegmatic.

Practices such as bleeding or applying hot cups to a person were based on the humor theory of surpluses of fluids.

Methods of treatment like bloodletting, emetics and purges were aimed at expelling a harmful surplus of a humor. Herbs and foods were used to counter symptoms of disease.

Aelius Galenus

 was a prominent Greek physician and surgeon who influenced the development of anatomy, physiology, pathology, pharmacology, and neurology.

Galen showed that the brain controls all the motions of the muscles by means of the cranial and peripheral nerves. Galen performed anatomical dissections on animals.

Galen believed that the venous system was separate from the arterial system: venous blood was generated in the liver and arterial blood originated in the heart. He believed that blood passed between the ventricles by means of invisible pores. The heart produced heat,  the arteries cooled the blood and the lungs fanned and cooled the heart itself.

Andreas Vesalius (1514 –1564)

 is the author of an influential book on human anatomy, De humani corporis fabrica (On the Fabric of the Human Body). He is referred to as the founder of modern human anatomy. 

     

Miguel Servetus (1509– 1553)

was a Renaissance Spanish theologian and physician. He described the function of pulmonary circulation: that the blood of the pulmonary circulation flows from the heart to the lungs.

Servetus was denounced as a heretic and condemned by Jean Calvin, the Protestant Reformer. Servetus was burned at the stake outside Geneva with the last copy of his book chained to his leg.

Discovery of circulation

William Harvey described the circulation of the blood

William Harvey (1578 – 1657)

 described completely and in detail the systemic circulation and properties of blood being pumped to the brain and body by the heart.
Before Harvey, it was believed that blood passed between the ventricles by means of invisible pores: the heart produced heat and during dilation arteries sucked in air; during contraction they discharged vapours to cool the blood.

De Motu Cordis (Motion of the Heart and Blood)

Harvey’s book describes the circulation of the blood and gives a perfectly clear and connected account of the action of the heart and the consequent movement of the blood around the body in a circuit.

Having only a tiny lens at his disposal, Harvey had to sometimes resort to theory – and not practical evidence.

He says:

"...I found the task so truly arduous... that I was almost tempted to think... that the movement of the heart was only to be comprehended by God. For I could neither rightly perceive at first when the systole and when the diastole took place by reason of the rapidity of the movement..."

William Withering ( 1741 – 1799)

 noticed a person with dropsy (swelling from congestive heart failure) improve remarkably after taking a traditional herbal remedy — from the foxglove plant. (Digitalis)

Digitalis purpurea (Common Foxglove)

 is used to increase cardiac contractility and as an antiarrhythmic agent, particularly in atrial fibrillation.  Digitalis was often prescribed for patients diagnosed with congestive heart failure. Safety concerns have led to the decline in therapeutic use of digoxin.

 

Modern cardiology

Einthoven received the Nobel prize for inventing the EKG

     

Willem Einthoven

 (1860 – 1927) invented the first practical electrocardiogram (ECG or EKG) and received the Nobel Prize in Medicine in 1924.

    

Mechanical heart valves

are prosthetics designed to replicate the function of the natural valves of the human heart.  A mechanical heart valve is intended to replace a diseased heart valve with its prosthetic equivalent.

Mechanical valves require lifelong treatment with anticoagulants (blood thinners).  Tissue heart valves made of pig heart valves have a limited lifespan.  The first artificial heart valve was the caged-ball, which utilizes a metal cage to house a silicone elastomer ball.

Tilting disk valves are made of a fabric covered metal ring which holds, using two metal supports, a disc that opens and closes as the heart pumps blood through the valve.

Angioplasty

Charles Dotter pioneered modern medicine with the invention of angioplasty and the catheter-delivered stent, which were first used to treat peripheral arterial disease.

Artificial heart

The first artificial heart to be successfully implanted in a human was the Jarvik-7, designed by a team including Robert Jarvik.

Pacemaker

In 1899, J A McWilliam caused rhythmic heart beats by applying electrical impulses to the human heart. In 1926, Dr Mark Lidwell and physicist Edgar Booth devised a portable pacemaker that was used to revive a stillborn infant. Albert Hyman described an electro-mechanical instrument powered by a spring-wound hand-cranked motor.
There was a public perception of interfering with nature by "reviving the dead".

Heart Sounds

lub dub     lub dub    lub dub    lub dub”

My heart goes boom

And my pulse begins to race,
It goes boom boody-boom boody-boom boody-boom
Boody-boom boody-boom boody-boom-boom-boom!

 

 

In the 1960 movie, The Millionairess, heiress Epifania Pargera (Sofia Loren) falls in love with Dr. Ahmed Kabir (Peter Sellers).  The song GOODNESS GRACIOUS ME captures the sound of a racing heart.

One day, many doctors would sound like Dr Kabir.

 

 

Heart sounds are generated by the flow of blood and reflect the turbulence created when the heart valves snap shut.

·        S₁   The first heart tone forms the "lub" of "lub-dub"  and is produced by the closing of the atrioventricular valves.

·        S₂   Second heart tone forms the "dub" of "lub-dub" and is made by the closing of the aortic and pulmonary valves.

·        S₃ Third heart sound. Rarely, there may be a third heart sound (ventricular gallop) lub-dub-ta". An S3 indicates increased volume of blood within the ventricle.

·        S₄ Fourth heart sound (presystolic or atrial gallop) is produced by the sound of blood being forced into a stiff or hypertrophic ventricle. "ta-lub-dub" .

·       Heart Murmurs: are a result of strong turbulent flow of blood making a whooshing sound. Regurgitation through the mitral valve is the most common murmur. Stenosis of the aortic valve is more common in older adults.

·        Clicks: Heart clicks are short, high-pitched sounds.

·        Rubs: can be heard in pericarditis, an inflammation of the pericardium, the sac surrounding the heart.

Dual Head Cardiology Stethoscope

Pediatrics Stethoscope

Lung Sounds

 

Phononocardiograms from normal and abnormal heart sounds

Diseases of the Heart

Atherosclerosis is the leading cause of heart attacks and angina”

Rheumatic heart disease

Rheumatic fever infection caused by streptococcal bacteria may scar and weaken heart valves, muscles, or the sac.

Valvular heart disease

Valves may narrow (stenosis), leak (regurgitation) or not close properly (prolapse).

Atherosclerosis

The walls of arteries can become thick and stiff because of the build up of fatty deposits called plaques. When this happens, the flow of blood is restricted.

High blood pressure (hypertension)

Excess force of blood pumping through blood vessels may overburden the heart and blood vessels and cause disease.

Coronary artery disease

Results from reduced blood supply to the heart caused by Atherosclerosis.  It is the leading cause of heart attacks and angina.

Cerebral vascular disease - Stroke

Parts of the brain may be damaged when the blood supply to the brain is interrupted and it is deprived of oxygen.

Peripheral arterial disease

Caused by narrow or blocked blood vessels in the legs.

Aneurysm

An aneurysm is a bulge or weakness in the wall of a blood vessel because of high blood pressure or a weak spot.

Heart attack—myocardial infarction

Occurs when the heart’s supply of blood is stopped. A heart attack need not be fatal.

Cardiomyopathy

Diseases of the heart muscle.

Pericardial disease

The pericardium sac that encases the heart can be affected by inflammation, fluid accumulation and stiffness.

Congenital heart disease

Examples are holes in the heart, abnormal valves, and abnormal heart chambers.

Heart failure

Happens when the heart’s muscle becomes too damaged to adequately pump the blood around the body.

Cardiovascular Disease

Poor diet, physical inactivity and smoking may lead to atherosclerosis”

Summary

A poor diet, physical inactivity and smoking may lead to atherosclerosis—narrowing and thickening of arteries due to deposition of fatty material in the walls of blood vessels.

Diet

A diet high in saturated fat increases the risk of heart disease and stroke. A diet low in fat and salt has a protective effect over the long term. Immoderate alcohol consumption will damage the heart muscle.

Cholesterol

A waxy, fat-like substance used to build cell walls and to make essential hormones. Cholesterol is carried through the blood by particles called lipoproteins.

 LDL low-density lipoproteins - carries the cholesterol around the body in the blood

 HDL high-density lipoproteins - transports cholesterol out of the blood into the liver.

Triglycerides are fats found in the blood. High levels of triglyceride increase the risk for heart disease.

Is heart disease hereditary?

Family history, ethnicity and age impact heart disease.

Hypertension (high blood pressure)

Can be diagnosed and managed with a healthy diet, exercise and medication.

Smoking and heart disease

Smoking damages the lining of blood vessels, increases fatty deposits in the arteries, increases blood clotting, and adversely affects blood lipid levels. Nicotine accelerates the heart rate and raises blood pressure.

Physical inactivity

Increases the risk of heart disease and stroke by 50%, obesity predisposes you to diabetes.

Type2 diabetes

Diabetes makes you twice as likely to develop cardiovascular disease.

Stress

A chronically stressful life, social isolation, anxiety and depression increase the risk of heart disease and stroke. Stress can lead to a compromised immune system and affect the nervous system. However, it is possible to cope with stress (the fight-or-flight response) and still be healthy.

Heart Procedures

Angiography is an imaging technique used to visualize the inside of blood”

SPECT nuclear imaging of the heart, short axis views

Angiography or arteriography

 A medical imaging technique used to visualize the inside of blood vessels.  This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy.

Electrocardiography

ECG or EKG is interpretation of the electrical activity of the heart as detected by electrodes attached to the surface of the skin.  An ECG picks up electrical impulses generated by the polarization and depolarization of cardiac tissue and translates into a waveform. The waveform is then used to measure the rate and regularity of heartbeats, as well as the size and position of the chambers and the presence of any damage to the heart.

Holter monitor

A portable device for continuously monitoring electrical activity of the cardiovascular system for at least 24 hours.

 Defibrillation

Treatment for life-threatening cardiac dysrhythmias, ventricular fibrillation and pulseless ventricular tachycardia.

A therapeutic dose of electrical energy is delivered to the heart with a device called a defibrillator.

This depolarizes a critical mass of the heart muscle, terminates the dysrhythmia and allows normal sinus rhythm to be reestablished by the body's natural pacemaker, in the sinoatrial node of the heart.

Aspirin

Aspirin has been found to be of benefit in those at low risk of heart disease. It does carry a risk of serious bleeding.

Statins

Statins such as Lipitor are effective in preventing further cardiovascular disease in people with a history of cardiovascular disease. In those with risk factors (but without cardiovascular disease)  statins appear to be beneficial with a decrease in mortality and further heart disease.

Heart Procedures

”Heart transplant survival periods average 15 years”

Heart transplant:

Takes a working heart from a recently deceased organ donor and implants it into the patient. Survival periods average 15 years – not a cure but a life-saving treatment.

A coronary stent:

is a tube placed in the coronary arteries that supply the heart, to keep the arteries open in the treatment of coronary heart disease.

Some cardiologists believe that stents are overused

Coronary Artery Bypass Graft (CABG) Quadruple Bypass

Coronary artery bypass surgery

Arteries or veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass atherosclerotic narrowing and improve the blood supply to the myocardium (heart muscle). This surgery is usually performed with the heart stopped.

   

Angioplasty

A collapsed balloon catheter is passed into the narrowed locations and then inflated using water pressure.

The balloon forces expansion and opens up the blood vessel for improved flow, and the balloon is then deflated and withdrawn. A stent may or may not be inserted at the time of ballooning to ensure the vessel remains open.

Heart:  User’s manual

”A low-fat, high fiber diet”

Diet

·        A low-fat, high fiber diet that consists mostly of unprocessed plant foods, with emphasis on a wide range of whole grains, legumes, and non-starchy vegetables and fruits.

·        Limit consumption of sugary drinks. Limit energy rich “fast foods” and red meat, and avoid processed meats.

·        Control portion size — say, 2000 calories per day.

·        Eat more vegetables and fruits—these are good sources of vitamins and minerals, are low in calories and rich in dietary fiber. They contain substances that may help prevent cardiovascular disease. 

·         Select whole grains—good sources of fiber and other nutrients.

·        Limit unhealthy fats and cholesterol
Saturated fat  - Less than 14 g a-day
Trans fat -  less than 2 g  –a day
Cholesterol -Less than 300 mg a day

·        Exercise—cardio training, 30 minutes or more, weight exercises for muscle mass.

·        Keep blood pressure within healthy limits.

·        Decrease body fat and weight if overweight or obese.

·        Reduce sugar consumption, calories, fats, additives, preservatives.

·        Manage and cope with stress.

·        Sleep—try to get seven hours of good, quality sleep.

·        Avoid tobacco and second hand smoke.

·        Limit alcohol.

·        Watch out for pollution.

·       Genetics—choose your parents wisely.

    

Rene Laennec

”At 14, he joined the Revolutionary army and was given the rank of surgeon”

Rene Theophile Hyacinthe Laennec was born in Quimper Lower Brittany on the 17th of February 1781. His father was a poor unsuccessful lawyer whose attempts at poetry met with failure. His mother died when he was five.

His uncle Guillaume was professor of Medicine at the University of Nantes.  Rene was sent to live with him. He first studied at a seminary and then became a student of his uncle. He went to lectures given by surgeons and became proficient in anatomy and clinical studies.

At the age of 14, he joined the Revolutionary army and was given the rank of surgeon 3rd class.

He was 5' 3" tall and suffered from asthma.

Paul Gauguin - Landscape of Brittany

Laennec Stethoscope

” He made a "log" by rolling sheets of paper into a cylinder”

Mediate Auscultation -1816

Laennec remembered a childhood trick:  "a simple fact in acoustics;   the great distinctness with which we hear the scratch of a pin at one end of a piece of wood, on applying the ear to the other."

He made a "log" by rolling sheets of paper into a cylinder. Laennec applied one end of it to the region of the heart and the other to his ear, and was surprised to hear a clear and distinct sound that allowed him to perceive the action of the heart.

This led to the invention of Laennec's monaural stethoscope in 1819. On the basis of his knowledge of normal and abnormal breath sounds, Laennec could diagnose bronchitis, pneumonia, and most importantly, tuberculosis, a prevalent disease that claimed many lives at the time.

Ironically, Laennec himself died of tuberculosis in 1826.

Laennec called this method Mediate Auscultation and published his findings in "Mémoire sur l'auscultation à l'aide de divers instrumens d'acoustique employée comme moyen d'exploration dans les maladies des viscères thoraciques et particulièrement dans la phthisie pulmonaire"

Early Stethoscopes -- Monaural and Binaural

Laennec’s monaural stethoscope is a solid wooden cylinder with a drilled center that could be unscrewed for carrying in the pocket. At one end, a chest piece was used to auscultate the heart. It could be removed and the large opening (bell) was used for listening to the lungs. By the 1850s, the monaural stethoscope was a mainstay of the physical examination.

Immediate Auscultation

” Immediate Auscultation was inconvenient,  indelicate,  and disgusting”

In 1816, Dr. Rene Laennec, an expert in chest diseases, was examining a young woman with heart problems. Painfully shy, he could not bring himself to press his ear to her chest, the only known method of auscultation.

“Auscultation is always inconvenient both to the physician and patient; in the case of females it is not only indelicate but often impracticable; and in that class of persons found in hospitals it is disgusting."

Note:

The cartoons shown here are typical of the attitudes of the 19th century.

Laennec’s Book

”This instrument I have denominated the Stethoscope”

In 1816, I was consulted by a young woman labouring under general symptoms of diseased heart, and in whose case percussion …was of little avail on account of the great degree of fatness, and by the age and sex of the patient.

I happened to recollect a simple and well-known fact in acoustics, …The fact I allude to is the great distinctness with which we hear the scratch of a pin at one end of a piece of wood, on applying our ear to the other.

Immediately, on this suggestion, I rolled a quire of paper into a kind of cylinder and applied one end of it to the region of the heart and the other to my ear, and was not a little surprised and pleased, to find that I could thereby perceive the action of the heart in a manner much more clear and distinct than I had ever been able to do by the immediate application of the ear.

The first instrument, which I used was a cylinder of paper, formed of three quires, compactly rolled together, and kept in shape by paste.

I now employ a cylinder of wood, an inch and a half in diameter, and a foot long, perforated longitudinally by a bore three lines wide, and hollowed out into a funnel-shape, to the depth of an inch and a half at one of its extremities.

This instrument I have denominated the Stethoscope.

Diseases of the heart have been more frequent in consequence of the tremendous agitation produced by the French Revolution.

A nun, fifty years of age, had been affected for twelve years with all the symptoms of disease of the heart.... I immediately reduced her food to one-fourth of her former allowance, and bled her once a fortnight... and in the course of six months all the symptoms had disappeared.

De L’Auscultation Mediate

”In 1822 Laennec, the cardiologist, earned $688,000”

Laennec’s Family

Laennec was married late in life and had had no children. At the end, he practiced only as a consulting physician.

Death

Laennec's exhibited the  external symptoms of consumption; and its nature was confirmed by his own invention to be tubercles, in a state of softening in his lungs— we assume phthisis puhnoitalis.

 A hard irregular tumor in the abdomen had been discovered, but there was no post-mortem.

Laennec was only 45 years old when he died on the 13th of August, 1826.

Laennec’s Income (1822)

10,000 francs from the Faculte de Medecine

6,000, from the College de France

4,000; from the Duchess of Herri and

23,000 from his private practice.

43,000 francs TOTAL

$688,000 (today)

 (The value of a dollar has gone up 80 times, 5 francs to a dollar —  circa 1822 )

Single Head Stethoscope

Stethoscope with Bell

Evolution of Stethoscopes

”The Camman stethoscope had ear-tips made of ivory”

Name

The stethoscope (from Greek στηθοσκόπιο, from, stéthos - chest and skopé - examination) is an acoustic medical device for auscultation, or listening to the internal sounds of an animal or human body. It is used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure.

From the 1824 London Times

" A wonderful instrument called the Stethoscope, invented a few months ago, for the purpose of ascertaining the different stages of pulmonary affections, is now in complete vogue at Paris. It is merely a hollow wooden tube, about a foot in length (a common flute, with holes stopped and the top open, would do, perhaps just as well). One end is applied to the breast of the patient. The other to the ear of the physician, and according to the different sounds, harsh, hollow, soft loud etc. he judges of the state of the disease. It is quite a fashion if a person complains of a cough, to have recourse to the miraculous tube, which, however, cannot effect a cure; but should you unfortunately perceive in the countenance of the Doctor, that he fancies certain symptoms exist, it is very likely that a nervous person might become seriously indisposed and convert the supposition into reality."

 

Cammann

In 1843, George P. Cammann (New York City) developed the first flexible binaural stethoscope from which sound could be heard simultaneously with both ears. By 1855, Cammann's stethoscope was made with an ebony chest-piece and flexible tubing made of spirals of wire covered with layers of silk dipped in gum elastic. The ear-tips were made of ivory.

    

Dr. David Littmann, M.D.

”His parents were Jewish immigrants from Ukraine”

David Littmann

(7/28/1906–1/1/1981) was born in Chelsea Massachusetts to Issac Litman and Sadie Zewat Litman. His parents were Jewish immigrants from Novogrod Wolyn, ( Zwill) Ukraine in the Russian Empire.

Early career

David obtained his medical degree from Tufts Medical School and interned at Harrisburg Hospital, Pa. His residency training was in internal medicine and cardiology at Boston City Hospital. He was in private practice for ten years before joining the Army Medical Corps. He spent most of his Army career in Greenland and was discharged in 1946 with a rank of major.

He was chief of cardiology at the West Roxbury Veterans Administration Medical Center for 25 years, associate clinical professor emeritus of medicine at Harvard Medical School, and a lecturer in medicine at Tufts Medical.

His wife Anna Mae was a Registered Nurse.

Fame

Littmann was an authority in the field of electrocardiography.  He has a long list of published scientific papers. He pioneered the practice of coronary angiography, which visualizes diseased coronary arteries.

He described a new technique to perform a more sensitive exercise test in the detection of coronary heart disease. He was the first to characterize the electrocardiogram in patients with pulmonary emphysema.

Littmann was "an inveterate gadgeteer" because he was always tinkering with the tools of his trade. In addition to the Stethoscope, he invented a Catheter, a Multi-Valve for use in coronary angiography, and a Electrocardiogram (EKG) Mounter, which resulted in an enormous savings in time and effort on the part of the EKG technician.

He published "Textbook of Electrocardiography," a text that is now standard among students and physicians.

Cardionics Stethoscope

”Dave Littmann was always looking to make a better mousetrap”

 

Dr. David Littmann set out to design a stethoscope with a louder and clearer sound. He eliminated acoustic leakage found in older instruments that were thick, bulky, heavy, and cumbersome. 

He eliminated kinks in the tubing. His rim and diaphragm combination delivered an airtight acoustic seal. Soft sealing ear-tips were comfortable and isolated external noise.

Dr. Littmann described his "ideal" stethoscope in an issue of the AMA journal. The device included an "open chest piece for the appreciation of low-pitched sounds, a closed chest piece with a stiff plastic diaphragm to filter-out low-pitched sounds, firm tubing with a single lumen bore, the shortest practical overall length, a spring with precise tension to hold the ear tubes apart, and light and convenient to carry and use."

His colleagues remember "Dave Littmann was always looking to make a better mousetrap".  Littmann toiled on his new stethoscope designs in his basement, where he had set up a sophisticated workshop with a complete set of metalworking tools.

"Dave went through 30 different iterations before he came to the one he liked."

      

With the help of a modest advertising budget, Littmann was receiving regular orders for his stethoscope. "He was selling 10 to 20 of them a week at that time."  His wife would box them up and mail them the next morning.

By 1961, he formed Cardiosonics with Gustav Machlup.

Over the next six years, Cardiosonics grew in profitability. In 1967, industry giant XX acquired Dr David Littmann's company.

Dr. Littmann continued to act as a consultant with XX after the acquisition. "He used to come in two days a week, and he worked on stethoscopes in the plant basement. He was very dynamic; his energy was infectious. He was also very down-to-earth."

Dr. Littmann’s legacy

” 94% of US cardiologists are male,  92% of nurses are female”

Entrepreneur

Dr. David Littmann and Gustav F. Machlup were the founders of the Cardionics Company. At that time, the stethoscope line consisted of two key models, the doctor's stethoscope and the nurse's stethoscope.
On April 1st, 1967, a large corporation acquired Cardiosonics, Inc. — the small Cambridge, Massachusetts company.

Nurse’s model

Dr Littmann targeted the higher quality cardiology stethoscopes towards male doctors while the cheaper lighter nurse’s models were offered in “feminine” colors. In 2014, 94% of US cardiologists (median income $512k)  are male while 92% of nurses (median income $ 65k) are female. 

Market domination

By 2014, his company sold 95% of high-end cardiology quality stethoscopes and there was no viable competition.

Ironically, doctors in third world countries came to identify the expensive brand as a badge of acceptance.

Profitability

In 2014 the profit margin on his cardiology scopes was estimated at 1500 % (ratio of list price to cost of manufacture).

Innovation

The basic models have seen little change since Dr. Littmann’s time. The company does offer over fifty models.

A cold and distant Zayde

David Littmann’s grandson, Chef Jay Littmann, is famous for his healthy cookies and for his book about his early life.

"The money had actually come from my paternal grandfather, who was one of perhaps four top heart specialists in 1950's and 1960's. I never knew David Littmann, M.D., that well. He was pretty distant and cold as far as family was concerned, not unlike my father.“

“The large corporation company eventually bought that stethoscope from my grandfather and hired him as a consultant. Lucky for us, he wanted to share the wealth." 

   

   

The ideal stethoscope

Long tubes may attenuate the audio signal”

Head

The head is made of solid stainless steel.  A heavy piece is more stable and resonant. The conical shape acts as an acoustic cavity. The rigid rim will allow for a tight acoustic seal. Aluminum heads are found in cheaper models.

In a dual head stethoscope, the swivel mechanism must be tight and balanced.  For lower frequencies, the Bell side must be a deep spherical cavity.

Diaphragm

The diaphragm must be made of a rigid “poisson” material.  It has to be thin and uniform to pick up faint body sounds. The rim must be elastic and form a leak proof seal. A soft rim will not chill” and shock the patient.

Tube

Heavier tubes will isolate sound but are less convenient. 21” long tubes are typical. Longer tubes may attenuate the audio signal. All tubes are now non-latex for allergy considerations.

Binaural

The binaural (earpieces) is bent at a 15-degree angle for ergonomics. Dual leaf springs allow for just the right amount of tension — for comfort.

Ear tips

The ear tips must be soft and flexible and fit tightly and comfortably into the ear cavity.

Types of Stethoscopes

The diaphragm for higher frequencies the bell for lower  frequencies

Acoustic

The diaphragm when placed on the patient picks up vibrations that create acoustic sound waves in the cavity of the metal head. These waves travel through the flexible tube to the ear of the listener. Tightly sealed ear tips help to make the sound clear and distinct.

Bell

For the Bell function, a hollow cavity directly transfers the sound waves from the body to the ear via the tubes.

The diaphragm responds better to higher frequencies while the bell is more suited to lower frequencies.

Single Head

Single head stethoscopes are generally bigger and louder. They are preferred by cardiologists. EMT’s like their simplicity and function - in an ambulance with a siren.

Training

This stethoscope has two earpieces — for the student and the teacher.

Fetal stethoscope

 The Pinard is an acoustic stethoscope shaped like a listening trumpet. It is placed against the abdomen of a pregnant woman to listen to the heart sounds of the fetus.

Electronic

In an electronic stethoscope, a sensor converts vibrations into an electrical signal that is amplified and heard through earphones.  Some stethoscopes have wireless and recording functions. Novel piezo material is better than conventional microphones in picking up body signals.

Efforts to implement automated analysis algorithms and perform remote diagnosis are being made. However, using only noisy imprecise heart sounds to perform complex analysis would appear to be illogical.

Future

The future of stethoscopes is uncertain. With the advent of advanced testing methodologies (visual and ultra sound technologies) -  “the art of auscultation may be dying”.

Ergonomic Art

”Form and Function”

Form and Function

In 2009, Hungarian artist Tibor Vojtko was commissioned to design an elegant yet functional stethoscope.

Vojtko began by placing modeling clay on a traditional stethoscope and molding it to the contours of his grip. The result was the perfect ergonomic design that echoed the fit and the curves of the human hand. It was comfortable and yet maneuverable.

The clay model was translated into a CAD design to create a single head stethoscope creating a breakthrough in ergonomic artistry, marrying form to function.

“We were able to scale down the original design to fit all hand sizes”. says Vojtko.

Electronic Stethoscope

”Startede med fiasco ”

Inventors

In 1995, in Struer, Denmark, the Medicom division of Bang & Olufsen, invents a beautiful medical instrument - “a highly innovative device that can diagnose calcification of heart valves by the sound of flaps.“

Bjørn Knud Andersen, a specialist in biomedical acoustics, is the inventor of the stethoscope sensor technology.

Tina Holm Sorensen, industrial designer, is responsible for the elegant ergonomic design that makes all user features accessible from a centrally located control button.

Other members of the team are Sven Erik Poulsen, Giørtz Christian Pedersen, Casper Stokbro Sorensen, and Hans Jorgen Jensen.

       

Patents

Medicom acquires several patents for the technology behind this innovative solution. “There was a need for many disciplines in the development process.”

Started with failure

However, the success story of the digital stethoscope started with a commercial failure. “The company lacked the proper contact with the market and the product was hardly sold.”

The company looks for a partner who knows the difficult and conservative medical device market. They visit the four largest companies in the world - armed with the device and patents.  XXXX says ''Yes'', and since 1997, it is marketed as the XXX electronic stethoscope.

Startede med fiasco

“Men succes-historien med det digital stetoskop startede egentlig med en kommerciel fiasko. Virksomheden, som dengang hed B&O Technology, havde i 1995 udviklet et yderst innovativt apparat, som kan diagnosticere tilkalkning af hjerteklapper via lyden fra klapperne. Det sparer en ellers smertefuld og dyr undersøgelse, men virksomheden manglede den rette kontakt til markedet, og produktet blev stort set ikke solgt.”

Something is rotten in the state of Denmark

”XXX electronic stethoscope was created by Bang & Olufsen”

Sweet Danish

The digital platform of sensor, speaker, and digital signal processor was developed by Bang & Olufsen Medicom in Struer, Denmark.

The software was developed by Bang & Olufsen.

The product is manufactured in Denmark.  BUT

The Bang & Olufsen Electronic Stethoscope is sold by XXXXX St. Paul, Minnesota.

MADE IN DENMARK

Awards:

Product of the Year winner - 1989.

“Bang & Olufsen Medicom has existed - and fared well - since 1989. Its’ winner is the digital stethoscope, its first independently developed and manufactured product. It is  based on the group's vast knowledge and patent portfolio in audio technology.”

"We are very proud and honored to receive the 2001 Product Award”, says project leader and Engineering engineer Hans Jorgen Jensen of bang & Olufsen.

 

The Bang & Olufsen Electronic Stethoscope a.k.a.
 XXXX electronics stethoscope is neither
Mined nor Manufactured in Minnesota
“where the women are strong,
  the men are good looking, and
 the children are all above average”

 

A Stethoscope with DSP

”Digital Signal Processing to deliver an enhanced signal

    

 

The Fourier transform is a mathematical transformation employed to transform signals between time (or spatial) domain and frequency domain, for any real number ξ.

The Kalman filter, also known as linear quadratic estimation, is an algorithm that operates recursively on streams of noisy input data to produce a statistically optimal estimate of the underlying system state.

The Kalman filter model assumes the true state at time k is evolved from the state at (k-1) according to    

 

Intelligent stethoscope with Digital Signal Processing   —  Designed in the USA by KilaScopes

Stethoscope WARS

”XXX has 95% of the cardiology stethoscope market

Lawsuit

XX sued KilaScopes and its owners for violating XX trademarks. At trial in the US District Court of Minnesota,  Minneapolis, KilaScopes countered that:

·        XXX was arrogant and filled with hubris.

·        XX had hoarded trademarks and used legal procedures to stifle competition.

·        XXX made a profit of 2000% on some stethoscopes.

·        XX controlled 95% of the cardiac stethoscope market.

·        XXX’s trademarks were weak generic terms that had been diluted and were available to the public by the fair use doctrine — much like the Scotch brand.

Kila lost the case and the subsequent appeal with the US Court of Appeals.

XX was entitled to part of its’ $ 1.5 million legal costs but not to any punitive damages.

The term “stethoscope” is not yet trademarked by XX.

Intellectual Property

XX owns the “XX” trademark. It was initially rejected because individual’s names cannot be trademarked.

At first, 3XXs trademark “Master Cardiology” was rejected. But it was  miraculously approved on appeal by a XX lawyer who had previously worked for the trademark office.

XX’s patent for an earpiece is similar in design to a rubber syringe or a turkey baster.  XX sells ear tips for $ 12.

XX has a trademark on the term “XXX” which critics claim is a generic English term.

“Vital signs strong forXX's stethoscope business”

“XX sold tens of thousands of its XXX and XXX scopes” wrote U.S. District Court Judge Ann Montgomery. "The XXX brand is extremely strong in the stethoscope market, having captured 70 percent of  sales". "XX sells over half a million XXX stethoscopes, earning tens of millions of dollars annually."

Artist -JOYCE GRANTHAM

water color  - back cover

Artist - TIBOR VOJTKO

sculpture  - “the Boxer

CREDITS

page    Description,  Author

3          Cardiovascular system,    medicalanatomy.net,  (1)

3          Cardiovascular system,    Bryan Brandenburg ,  (1)

3          Alveoli,    Helix84,  (1)

5          Anatomy of the heart,    BruceBlaus.,  (1)

5          Normal Blood Flow,    BruceBlaus.,  (1)

7          Lungs,    Patrick J. Lynch,   (1)

9          London Olympics 2012,    Tom Page,  (1)

11        Caduceous,    Rama,  (1)

11        Army medical core,     (1)

11        Rod of Asclepius,    Claudia von Aponte,  (1)

13        Statue of hippocrates,    Tedmek,  (1)

15        Miguel Servetus,    Giovanni Dall'Orto,,  (1)

15        Four temperaments,    Charles Le Brun, (Myrabella),  (1)

15        Andre Vesale,    Hamman, Edouard,  (1)

17        William Withering,    W. Bond,  Carl Frederik von Breda,  (1)

17        Arm,    Sigerist, Henry E. ,  (1)

17        William Harvey,    www.peoples.ru,  (1)

17        Foxglove flower,    Kurt Stüber,  (1)

19        Eintohoven,     (1)

19        Pacemaker,    Professor Marko Turina,  (1)

19        Valve 1,    Wellcome Museum, London, Dr. Mirko Junge,  (1)

19        Valve2,    SynCardia Systems,  (1)

19        ekg,    Hazmat2,  Hank van Helvete,  (1)

20        Song - millionairess,    1960 film 20th Century Fox

21        Peter Sellers,    Publicity handout,  (1)

21        Sofia Loren,    Publicity handout,  (1)

25        Phonocardiograms,    Madhero88,  (1)

27        Blocked blood vessel,  (1)

27        Valves,   (1)

27        Narrow blood vessel,    (1)

29        Card player,    Paul Cézanne,  (1)

29        Sorrowing old man ,Van gogh,    Pushkin Museum,  (1)

29        Pastry,    John Liu,  (1)

31        Nuclear image of the heart,    Patrick J. Lynch,  (1)

32        Stent procedure,    J. Heuser,  (1)

33        Coronary bypass,    Blausen.com,  (1)

33        Angioplasty,    Blausen Inc,  (1)

35        Myron's Discobolus,    Glyptothek, Munich (Rotatebot)  (1)

35        Fruit,    Bill Ebbesen,,  (1)

36        Landscape_of_Brittany,    Paul Gauguin (1848–1903),  (1)

37        Laennec,    PHGCOM,  (1)

39        Wood stethoscope,    Science Museum London,  (1)

41        Auscultation,    L'ange Gardien G. Hoffmann (nih.gov)

43        Book by Laennec,  (1)

45        Laennec,    Théobald Chartran,  (1)

49        Old stethoscopes,   Popular Science Monthly,  (1)

49        Old stethoscopes,   Popular Science Monthly,  (1)

49        Old stethoscopes,    ,  (1)

49        Old stethoscopes,    Brian Stansberry,  (1)

            Old stethoscopes,    Takkk,  (1)

54        How to Get From There to Here, 
            Jay Littmann  ISBN 978-1934572399

62        “Startede med fiasko,    Ingenioren (2)

63        Electronic stethoscope.jpg,    ,  (1)

65        Hamlet,    stephen boisvert,  (1)

68        Vital signs strong for XX,    Pioneer Press (3)

 

(1)  Wikipedia sites  http://commons.wikimedia.org , http://wikimediafoundation.org, http://en.wikipedia.org/wiki/

(2)  http://ing.dk/artikel/stetoskop-vinder-ingeniorens-produktpris-43321

(3)   http://www.twincities.com/business/ci_18965424

Copyrights and Trademarks

Wikipedia and Wiki Commons media and text is reproduced under the creative commons license. (see front cover)

 

Section 107 of U.S.C. TITLE 17 of Copyright Law, states that "the fair use of a copyrighted work, .. for purposes such as criticism, comment, teaching, scholarship, or research, is not an infringement of copyright."

 

Faithful reproductions of two-dimensional public domain works of art are public domain.

 

Works of the US government are public domain.

 

Work published in the United States between 1923 and 1977 and without a copyright notice  is in the public domain.

 

Usage of publicity handouts and brief extracts from news item of public figures and issues is fair use.

XX ® and XXX ® are trademarks of XX corp. XX has not sponsored or endorsed this book and there is no affiliation or other connection between XX corp. and the author.

These trademarks are used under the "nominative fair use" doctrine.

 

The name Dr David Littmann refers to the man and not the product.

 

Pictures of stethoscopes are courtesy of Kilascopes.

 

Water print of Dr. David Littmann is courtesy of Joyce Grantham.

Print of “the boxer” is courtesy of Tibor Vojtko.

 

 

 

Title and year

Stethoscopes, Rene Laennec to David Littmann © 2014  Prad Mohan

 

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