What is the difference between Left ventricular hypertrophy and an \\\"athletic heart/\\\" How can one be a serious medical condition caused by high BP and smoking and the other be an indication of a highly trained athlete?? Help???
What is the difference between Left ventricular hypertrophy and an \\\"athletic heart/\\\" How can one be a serious medical condition caused by high BP and smoking and the other be an indication of a highly trained athlete?? Help???
bump...why cant anyone figure this out???
it has to do not only with the size, but the particular distribution of that size, and the amount of "squeeze" that the muscle is giving.
Put simply, in chronic, untreated hypertension, the walls of the left ventricle thicken - usually in an asymmetric manner. This thickening is not simply a result of new muscle growth from pumping against a pressure head, but of ABNORMAL muscle growth. (There are also microvascular changes that I'm ignoring, as well as the co-morbid conditions that often accompany high blood pressure such as diabetes, hyperlipidemia, and endovascular damage.) The abnormal muscle does not pump as well - over time - as the normal muscle growth.
In the athletic heart, there is a more balanced, symmetric thickening of all the heart chambers, though it may be more pronounced in the left ventricle. There is concomitant microvascular growth as well, which provides the blood flow necessary for proper growth.
Dave hit this right on the head.
There's another difference, too. In LVH caused from years of unchecked high blood pressure, the thickening of the wall is also accompanied by the wall becoming stiffer. So, while the hypertrophy of the muscle wall is an adaptation to try to generate more force to push blood, that force production is only available in a small range of the contraction, therefore stroke volume cannot increase and in some cases will decrease over time.
The hypertophy in the athletic heart is not accompanied by the same stiffening. Therefore the muscle retains full dynamic range and can generate huge stroke volumes when necessary.
Interstingly, in looking at ECGs from heart patients with VH and endurance athletes, you will often see some very similar changes from "normal" as long as the heart patient doesn't also have some other kind of anomaly like bundle blockage, ST depression, or arrhythmia. Namely, as the heart hypertrophies, its axis tilts furhter, so that the heart sits at a greater angle than an unathletic but healthy person. You'll see the changes in the V1-V6 leads, in that the pole of the heart moves away from V4 and more toward V5 and V6. This is why cardiologists used to consider endurance exercise bad for you way back in the 1950s or so. But the electrical activity measurements of the ECG are only a small picture of heart function. Obviously when looking at BP, HR, SV, TPR, and any other host of varialbes, they will be different between an athletic person and someone with ventricular hypertophy.