Will Cardiac Diagnostics Work?

We, as physicians, are used to measuring things.  We measure temperature, blood pressure, height and weight.  We measure your blood counts and the level of cholesterol in your blood.  We are used to measuring things and part of this derives from the science of medicine.

In general, we believe that it you can measure something you will understand something better and possibly begin to change it.  With the development of blood glucose monitors,  we are able to be more precise in our control of diabetes.  Those of you who are old enough will remember when glucose control was measured by urine test strips.  Glucose monitors are now an essential part of diabetic care and are approved by Medicare and Insurance companies.  There is some debate as to whether this glucose control does any real good but it is accepted by both physicians and the public.

How do you measure a hearts function.  It is not blood pressure because a normal heart can have a blood pressure of 90/60; a failing heart can have a blood pressure of 200/110.  The physical signs are rapid weight gain and special sounds we hear in the lungs called rales, which is derived from the French word rattle.  A Frenchman Rene Laennec in 1816 developed the first stethoscope, again to measure something.

We measure heart function by measuring the pressure in the heart and lungs.  I do this daily at cardiac cath and we have exquisite knowledge about these dynamics.  We can also measure the pressures non-invasively by echocardiogram.

In the late 1960’s, two physicians at Cedars-Sinai in Los Angeles developed a catheter that could be placed in a vein and threaded into the heart to measure the pressures in the lungs.  Initially known as a Swan-Ganz catheter after its inventors, Jeremy Swan and William Ganz, it eventually became known as a Swan. (Don’t ever be the second name on an invention.)  These catheters saved millions of lives and led to an era of improved intensive care.  The seminal article was published in the New England Journal of Medicine in August 1970.

We now have two ways that I know of to measure the status of the heart on a day to day basis.  The science of these measurements is well understood.  FDA before approval of the devices and the measurements demanded proof that the obtaining of the measurements led to good clinical outcomes such as staying out of the hospital with heart failure.  We at the Jim Moran Heart and Vascular Institute participated in one of the device approval trials.

Next…the devices and why they may help us better care for patients.

Tags: blood glucose, blood pressure, Cholesterol, diabetes
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