Blood pressure is a measurement of cardiovascular health, recorded as two distinct numbers: systolic (top) and diastolic (bottom). Both values offer important insights into how the heart and blood vessels are functioning. A reading of 119/55 millimeters of mercury (mm Hg) requires looking at each number individually to understand the full picture.
Defining Systolic and Diastolic Pressure
The two numbers represent the force exerted by the blood against the artery walls at different points in the heart’s cycle.
The top number is the systolic pressure, which reflects the maximum force when the heart contracts to push blood out into the body. This pressure is generated by the heart’s pumping action.
The lower number is the diastolic pressure, which represents the minimum force when the heart is at rest between beats. During this resting phase, the heart refills with blood, and the diastolic reading indicates the residual pressure within the arteries. This pressure is important because it is when the heart’s own coronary arteries receive oxygenated blood. If this pressure falls too low, the heart muscle may not receive enough blood flow, a condition called ischemia.
Interpreting Your Specific Reading of 119/55
A reading of 119/55 is categorized by its highest component, the systolic number. A systolic pressure below 120 mm Hg and a diastolic pressure below 80 mm Hg is considered Normal blood pressure. Your systolic reading of 119 mm Hg falls within this desirable range, indicating healthy pressure during the heart’s pumping phase.
The diastolic number of 55 mm Hg is a point of attention, as a healthy diastolic pressure is generally not below 60 mm Hg. A reading of 55 mm Hg is considered low, which may be referred to as isolated diastolic hypotension if the systolic pressure remains normal. This combination creates a significant difference between the two numbers, known as the pulse pressure.
The pulse pressure is calculated by subtracting the diastolic number from the systolic number (119 minus 55), resulting in 64 mm Hg. The average pulse pressure is around 40 mm Hg, and 60 mm Hg or more is considered a wide pulse pressure. A wide pulse pressure can indicate stiffness or hardening of the arteries (arteriosclerosis), which increases the risk of heart disease. This reading suggests that while the heart is pumping effectively, the elasticity of the blood vessels may warrant further evaluation.
Common Reasons for Low Diastolic Pressure
A low diastolic reading of 55 mm Hg can be caused by various factors, some harmless and others requiring medical attention. For example, highly conditioned athletes often have naturally lower diastolic pressure because their hearts are more efficient. Simple factors like dehydration can also temporarily cause a drop in blood pressure.
Certain medications, such as alpha-blockers or over-the-counter diuretics, can contribute to isolated low diastolic pressure. Aging also causes the natural stiffening of the arteries, which often results in the systolic pressure rising and the diastolic pressure falling, leading to a wider pulse pressure.
In some cases, persistently low diastolic pressure can signal a structural heart problem, such as aortic valve regurgitation, where blood leaks backward. If low diastolic pressure causes symptoms like dizziness, lightheadedness, or fatigue, consult a physician promptly. A diastolic reading consistently below 60 mm Hg should be discussed with a healthcare provider to determine the underlying cause.