Cardiac fitness index based on treadmill hr monitoring: its novelty, providing cardiac diagnostics in terms of correlation of cfi with lv ef, and enabling medical management of the subject

In a medical clinic, cardiologists monitor the cardiac health of patients by monitoring their heart rate while on the treadmill and after the patient has gone off the treadmill. However, they only monitor their heart rate values, and not the trend of the heart rate variation. Then, if their heart rate goes up very fast, and to very high values, it is an indication of cardiac dysfunction, for which further tests are recommended. However, this is an empirical and subjective assessment of a patient’s heart function assessment. In our opinion, we need to know (i)the rate at which the heart rate keeps increasing while walking on the treadmill, and (ii) the rate at which it keeps decreasing off of the treadmill, to help us accurately determine the health state of a patient’s heart. For this purpose, we need to fit mathematical equations to simulate the monitored heart rate vs time data, while on and off the treadmill. In order to quantitively characterize cardiac fitness, we need to develop an index which describes the trend of heart rate variation while striding on the treadmill and after getting off the treadmill. In this paper, we have first determined the heart rate variation equations. The equation for heart rate variation while striding on the treadmill is given byHR=HRo×t^k1, where HRo is the initial heartrate when getting on the treadmill. Then the equation for heart rate variation after getting off the treadmill is given by HR=HRe×t^(-k2), where HRe is the heart rate reached at the end of striding on the treadmill. Among our four subjects, the range of k1 was found to be 0.2 to 0.25. The range of k2 was found to be -0.2 to -0.3. Then we have formulated the Cardiac Fitness Index (CFI) as follows: CFI = k2/k1×HRo/((HRe-HRo))× ((HRe-HRf))/HRe ×100 wherein HRo is the initial rate at the time of getting on the treadmill, HRe is the heart rate at the end of 10 minutes on the treadmill, and HRf is the final value of the heart rate at 10 minutes after getting off the treadmill. We have evaluated four patients and calculated the values of their CFIs. Based on this, we found the range of CFI to be from 87 to 34.Now our intent is to monitor more subjects and find out the CFI ranges for normal subjects and subjects with cardiac symptoms. This can enable the cardiologist to diagnose a subject with cardiac issues and recommend the subject for further tests, to determine the precise nature of the cardiac problem. For this purpose, we are proposing that for these patients, we also monitor their ejection fraction (EF) noninvasively by echocardiography. Then, the novelty of CFI in denoting the cardiac health of a subject, can be obtained by corelating the CFI with the noninvasive echocardiographic measurement of ejection fraction of patients. By determining this correlation, the patient’s health can be monitored very conveniently and accurately by just determining the CFI. Then our Cardiac Fitness Index (CFI) can be employed very effectively by cardiologists to assess the cardiac health state of patients. In fact, it can also be people at home to determine the cardiac fitness, and to stay fit. Thus, our paper will enable both medical and non-medical people to assess their cardiac fitness, and hence will have a wide range of applications.