From our anonymous insider…
Sonographers and clinicians demonstrated echocardiography. The ultrasound radiologist said, “This will be the moment everyone is captivated by ultrasound.” She was not wrong as we gazed at our hearts in action. Echos are a fantastic way to noninvasively get a snapshot of the heart. My classmates loved using the “color doppler” feature to visualize the blood flow in and out of the different heart chambers. Due to Doppler effect, blood flowing towards the transducer compresses the sound waves and thus reflects sound at a higher frequency; blood flowing away from the transducer stretches the sound waves and thus reflects at a lower frequency.
Lectures continued on cardiac output and numerous regulatory mechanisms of the cardiovascular system. Cardiac output is governed by metabolic demands of the body. I was fascinated by the principle of “peripheral vessel capacitance”. Arterioles (small arteries) conduct rather than store blood. Arteriole smooth muscle tone determines the resistance of these rigid tubes by changing the diameter. Venules (small veins) are slack by comparison due to high levels of elastic fibers and the low amount of smooth muscle in their walls. Arterioles and venules behave as a combination of resistors and capacitors for blood. Venules collectively are a massive reservoir of blood. A sudden increase in cardiac output and increased blood pressure can be handled by charging the venule reservoir rather than by returning venous blood to the heart. In the event of a hemorrhage, the vessels will discharge to maintain arterial blood pressure. Smooth muscle contraction of the arteries increases resistance and thus decreases flow, whereas smooth muscle contraction of the venous system leads to a decrease in capacitance and increased flow. It seems to me most blood pressure research and pharmacological intervention is focused on manipulating arterial muscle tone. I wonder how venous tone may be dysregulated in pathologies such as hypertension? (see “How changes in venous capacitance modulate cardiac output”, Tyberg 2002)
The patient case involved a late-50s male who suffered a heart attack. “Jack” was also a type 1 diabetic diagnosed at an early age. He lost his financial industry job in 2009, along with his insurance, then had a heart attack a month later. During his week in the hospital, physicians put him into a medically-induced coma, which the patient said saved his brain function (because an awake brain would place a greater demand on the injured heart?). He recovered well and is back to work in a “less-stressful” job. The enormous bill was paid in full by a charitable organization associated with the hospital.
Due to his chronic condition, type 1 diabetes, he deals with nearly a dozen specialists, including an internist, rheumatologist, cardiologist and endocrinologist. He prioritises his cardiologist’s’ recommendation over treating his joint pain from type 1 diabetes after his rhematologist recommended he switch to a drug which his cardiologist vehemently opposed putting him on. Jack complains that he does not know how his heart is doing now. He lives with perpetual uncertainty. He knows he should lose 15-20 pounds. The cardiologist said the tests that might shed light on the heart’s condition are not economically justified. When Jack mentioned his concern, the cardiologist said, “the question for patients after the first heart attack is not if, it is when, the next heart attack will be.”
A quirky neurosurgeon presented his research interests to the class. He opened with, “Fracking will save neurosurgery!” He explained that neurosurgery involves an astronomically expensive procedure that, even when successful, frequently results in disabled individuals who cannot support themselves. “If a bomb went off at the neurosurgery conference, public health would not be affected. Only rich economies can support such a field.” His research dream is to find a neurosurgery procedure that has an actual economic benefit. This lecture was a good reminder that a country’s GDP is not a great measure of a country’s wealth; if everyone gets diabetes the GDP will go up from increased health care spending, but the average American will certainly not be better off.
Next, an ENT specialist described her interest in hearing loss. The ear is a masterful mechanical device that focuses sound waves and transmits it to a circular fluid drum called the cochlea. Sound energy hitting the ear vibrates the fluid inside the cochlea. Specialized nerve cells innervate the cochlea bearing tiny hair projections into the fluid that deform at pre-set frequencies. These nerve cells send this signal this information to create the sense of sound. Medicine now has the ability to implant artificial cochleas. Our ENT lecturer was trying to determine at what age these prosthetics should be implanted to get the best hearing outcome. She presented a case in which one sibling got an implant at age 3 and is now more or less normal while the sibling who also lost hearing at age 2 but didn’t get the implant until age 6 is struggling with both hearing and speech. She is able to surgically implant these devices without having done the grueling general surgery residency and also treats adults, thus breaking what we were told are the rules for choosing a specialty: (1) to cut or not to cut, and (2) do I like kids?
Statistics for the week… Study: 15 hours. Sleep: 7 hours/night; Fun: 1 night. Example fun: Double date with 24-year old classmate and his wife who is studying to become a physician’s assistant, followed by drinks at the new taco/tequila bar.
The Whole Book: http://tinyurl.com/MedicalSchool2020
“…if everyone gets diabetes the GDP will go up from increased health care spending…”
If I break this window, the GNP (Gross Neighborhood Product, of course) will go up from increased window-replacement spending.
“If a bomb went off at the neurosurgery conference, public health would not be affected…” His research dream is to find a neurosurgery procedure that has an actual economic benefit.
I would love to hear further elaboration on this. For the record, a relative was positively helped by brain surgery, and after about a year fully recovered.
J: I’m glad to hear about your relative’s recovery. However, one person’s situation doesn’t move the “public health” needle (so to speak) too much in a country of 325 million people.
To evaluate “public health” and “economic benefit” one would need to look at total spending on a type of procedure, the lives saved, the average level of recovery (can former patients work? do they need continuing care?), and the average age of the patients involved. You would also need to look at alternative ways to spend the money, e.g., send obese people on walking tours, pay people to stop smoking, etc.
“He lives with perpetual uncertainty.” That’s no different from your average Joe. How would the test (likely coronary angiography) change his management?