Blood pressure

Blood pressure (BP) is the pressure or blood force created during heart's muscle contraction, where blood moves through the vascular system. Systolic (SBP) and diastolic (DBP) blood pressures are expressed in different cardiac cycles. Systolic pressure is created during the contraction of the heart ventricles which is the max pressure in the vascular system, and diastolic pressure is the minimum pressure between ventricular contractions when the heart is in the rest. Systolic and diastolic blood pressures are expressed 125/85 mmHg which is due to normal blood pressure.

Blood pressure classification at the resting time [4-5]. It was believed that a correlation existed between blood pressure and physical activity. During physical activity the demand for oxygen and nutrition are increased, compared with rest time. Therefore, heart rate increases, pushing more blood into the vascular system. Energy expenditure is the most important single 16 variable describing the physical activity, believed to be related to the blood pressure. Fagard [27] found that there is no significant correlation between systolic, diastolic blood pressure and the energy expenditure (r=0.14, r=-0.02). However, another study showed that blood pressure decreases immediately after physical activities, systolic pressure was found to decrease by 3.84 and diastolic pressure by 2.58 mmHg [28]. Myrphy found the reduction of systolic blood pressure in woman to differ according to the physical activity effectuated, in his experiment the blood pressure was lowered after three short 10 min walks by between 7.4 and 7.3 mmHg, compared to one 30 min walk when the BP was lowered by between 4.6 and 5.9 mmHg [29].

According to American Heart Association (AHA) [5] and Yale University School of medicine heart book [4], resting blood pressure can be classified into cardiovascular risk groups, as shown in Table 3.2 (also similar classification belongs to WHO). Correct blood pressure estimation can be significant cardiovascular risk prevention. The Framingham Heart Study [30] found a correlation between SBP, DBP, pulse pressure (PP) and age. Advancing in age, the cardiovascular risk indicator shifts from SBP to DBP. Thus, in a 50 or younger age group, the systolic blood pressure is the strongest cardiovascular risk predictor. In ages between 50-59 SBP, DBP and PP provide similar risk indicators. However, in ages above 60 years, the strongest cardiovascular risk predictor is DBP. Long term prospective studies [31] showed that in ages from 40-69, a 20 mmHg difference from usual systolic BP and a 10 mmHg diastolic BP, correlates to doubling stroke and mortality rates. Hypertension, or increased blood pressure, forces to bring a greater payload to the heart. Leading consequences is enlarged heart muscle, which in time become stiff, weak and unable to pump blood efficiently. Therefore, this can lead to stroke, heart failure or even death [4]. During 1940 1950s the most common cause of death was hypertension. However, in recent days hypertension can be controlled with right medications.

Factors, which can change the blood pressure, are coffee, smoking, alcohol intake, medications, day of time [4].

2015 Heart Risk Warner