The sensation most commonly bringing atrial fibrillation to light is an awareness of the heartbeat. It may be described as a fluttering inside of the chest, the movements soft and irregular. This is in contrast to the regular pounding of a heart driven by exercise or fright.
If you lie motionless and pay close attention, you will feel your heart break the calm. The heart makes a tight fist that tilts and moves about in the chest while at its task. The whole body moves with it. The movement is generally ignored because our brain has the ability to filter sensations that are regular, consistent or expected. Perception of these sensations requires concentration.
During severe infection or under the influence of invigorating hormones, like that of the thyroid gland, the heart rate remains high at all times, often more than 100 beats each minute. Although there may be a generalized sensation of being ill at ease, the heart rate is rarely the focal point. In someone with low blood counts or with a heart that is severely diseased, blood delivery and heart rate at rest may be sufficient but reserve is immediately spent with the slightest movement. There is no place to call upon for reserve blood flow to the body but an increase in heart rate. For many people in these extremes, a hunger for breath is a more pressing concern than the pounding heart.
Irregularity is the principle indication that atrial fibrillation may be present. However, irregularity may be easily ignored. An occasional, brief change in the heart’s rhythm, for one beat or so, is universal. Like a missed musical note, attention to it is fleeting. The heart rate during or between episodes is normal. A single mistimed beat is usually described as extra because it originates from somewhere other than the heart’s normal bandleader. The off-timed work of the heart may occur with such short notice that no blood has been able to enter the main pumping chamber. The resultant heartbeat passes along no, or minimal impulse to the arteries. One may feel as if the heart had stopped, or the need for and act of a short intake of breath. In some, the pause is unnoticed, but the following beat produces discomfort. The bandleader, momentarily stunned by the effrontery of this “other” part of the heart that has chosen to speak, pauses. The intermission allows time for extra blood to enter the heart, making the next beat more forceful. The sensation has been described as an instant of fatigue, of breathlessness or as though the heart had “flopped” inside of the chest.
Atrial fibrillation is a sustained irregularity. The sensation accompanying its presence is often described as fluttering, racing, hammering, or even a “glimmer”. It is disquieting, if not uncomfortable. Anxiety accompanies the irregularity causing restlessness, while urging stillness. At onset, many will sit upright, as if at attention, soon changing position, seeking comfort that will not come, while the dominant hand unconsciously seeks the chest. Sweat comes to the brow and a breath will simply not make it all the way in. In some, the strangeness compels them to test its gravity by walking about, albeit cautiously. The loss of cardiac efficiency is sudden and may be profound. Any physical activity will require greater effort resulting in the sensation of fatigue. A day may seem to drag on without end and soon it becomes apparent that the night holds no promise of rest.
At first, such episodes may be brief. Someone who appears pale, breathless and seemingly incapacitated in one moment may look and feel quite normal an hour later. The sense of normality may last days, weeks, even months so that with the next occurrence, the prior event is a vague memory. Intermittence and our natural tendency to minimize sensations that have passed without a specific remedy are part of the reason that atrial fibrillation may be intermittently present for years before it is discovered.
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