To respond to the inital poster's concerns, yes there are differences between scopes. Most physicians in North America choose from among the following:
Littmann:
- Cardiology III
- Master Cardiology
Welch-Allyn:
- Elite series
- Harvey series
*'Original' Harvey (available in double and triple heads)
*'DLX' (Modern) Harvey (also in double and triple heads)
Hewlett Packard/Agilent
- Rappaport-Sprague
The most popular brand is undoubtedly the the Littmann. The company has much greater marketing resources than the other two, and has captured the stethoscope market in many countries. Of course, no amount of marketing will sustain an inferior product - the Littmann's mentioned above are good. I have even used the Classic II (usually used by nurses), and find its auscultatory capabilities reasonable. However they are certainly not the best stethoscopes.
The stethoscope traditionally used by classically trained cardiologists is the Sprague, developed and introduced more than 45 years ago by HP. It is still considered by cardiologists to be the gold standard acoustic stethoscope, with an outstanding high to low range. The one downside of the Sprague in my opinion is the dual tubing ie. each earpiece is connected to the chestpeice by its own tube, and these two tubes are held together by metal clips. While this is supposed to improve the quality of sound transmission, the two tubes rub together, introducing artifacts. Your ability to use the Sprague is, initially, a function of how long you have used it. However, that being said, once you have learnt to recognize what is simply the tube sound, you'd be hard pressed to get better acoustics from any scope.
The Harvey scopes were designed many years ago by Dr. Watkins Proctor Harvey, a famous cardiologist, who studied under Sam Levine at the Brigham. The DLX is the modern version of the original Harvey scope. The beauty of the Harvey is the excellence in design - the tubing, the weight, material, size and design of the chestpieces, the bianurals, all engineered to produce an exceptional auscultation instrument. In addition to the usual two heads, the Harvey triple head has an additional corrugated diaphragm. This special diaphragm has two unique properties - it amplifies heart sounds, and is able to pick up the lowest frequency heart sounds that may be heard by the human ear (eg., diastolic gallops). The flat diaphragm 'specializes' in high frequencies, and the bell lower frequencies. The bell is also sized differently than in other stethoscopes - it will fit in the intercostal spaces and 'cups' over the carotid region in the neck and the eyelids. The weight of the chestpeice has been designed so that when using the corrugated diapghragm and the bell, simply placing the piece on the chest wall produces the correct amount of pressure to hear the lower frequencies. The modern Harvey also solves the problem of having individual tubing - there is one tubing that has a slplit lumen, each going to one earpiece. This eliminates the tubing problem of the Sprague.
As a medical student, I owned and used a Littmann. However, when that got lost, for a time I used a Sprague I'd borrow from my seniors (all Cardiology fellows, and many med residents, at my institution own Spragues). I felt this was definitely a superior scope. I now own a DLX, which in my personal opinion is the best acoustic scope out there.
The "traditional" scopes like the Sprague and the Harvey were built in an era when bedside diagnosis was of paramount importance in medicine. Even the fact that their capabilities are "split" (you MUST switch over to the bell to hear lower frequencies, and the diaphragm to hear higher ones) I feel has helped me over the years to sharpen my clinical skill - you are forced to learn and understand the characteristics of each murmur, gallop, HS, etc... where's the best place to look for them, how they sound, their frequencies, their timing, what accentuates the murmur. I've noticed people who use the Littman just use the flat d - the claim is the patented "Littmann diaphragm" automatically turns into a bell if you release pressure on it. This may be so on a brand new one, but I don't for a moment buy it on a scope more than 6 months old. I think this has lead to a certain laziness in many students - they don't take the trouble to properly learn cardiac sounds, and correlate what they learn in the books with what they hear in clinical practice. Because they don't hear much. Which in turn can discourage learning and correlating. It's a vicious cycle. It is not helped when they are taught by a generation of physicians who have themselves lost the art and skill of bedside diagnosis, and for whom the exam isn't important - only the thousand dollar test.
Bottom line: whatever stethoscope you buy, make sure 1. it works and fits your ears, 2. you practice and practice and practice. Read up before you go out on the wards, and always correlate.
