The sensation of a heart pause or flutter during a violent cough is a common concern. The heart does not actually stop beating, but the feeling is a real physiological phenomenon. This temporary disturbance significantly affects the cardiovascular system, creating a sensation that can feel like a skipped or stopped beat. Understanding the mechanics of a cough and its immediate effect on blood flow provides a clear explanation for this alarming but usually harmless experience.
The Mechanics of a Powerful Cough
A forceful cough is a complex, coordinated reflex designed to clear airways, involving three distinct phases. It begins with a rapid, deep inspiration, which primes the lungs by maximizing the volume of air available. Following this intake, the glottis—the opening between the vocal cords—shuts tightly while the expiratory muscles contract powerfully.
This action against a closed glottis is the compression phase, causing a massive, rapid buildup of pressure within the chest cavity, known as intrathoracic pressure. This internal pressure can briefly soar to levels exceeding 300 millimeters of mercury (mm Hg). The final phase is the explosive expulsion, where the glottis suddenly opens, releasing the compressed air at high speeds. The purpose of this pressure spike is to generate the high-velocity airflow needed to dislodge mucus and foreign particles. The intensity of this mechanical event primarily influences the heart.
How Intrathoracic Pressure Affects Cardiac Function
The high intrathoracic pressure generated during the compression phase temporarily affects the heart and blood vessels. The chest cavity is physically compressed, which severely impedes the return of venous blood back to the right side of the heart. This mechanical squeeze is similar to the effect produced during a Valsalva maneuver, a controlled act of forced expiration against a closed airway. With less blood filling the heart’s chambers, cardiac output—the amount of blood the heart pumps out—temporarily drops. This reduction leads to an immediate, brief drop in systemic blood pressure.
The body engages compensatory mechanisms, such as the baroreceptor reflex, to stabilize pressure by causing rapid changes in heart rhythm and peripheral blood vessel constriction. This response often involves a temporary slowing of the heart rate (bradycardia) followed by a compensatory increase (tachycardia) once the cough is complete. The pressure can also physically compress the heart, sometimes pushing blood forward via the “thoracic pump” mechanism.
Understanding the Sensation of a Skipped Beat
The feeling of a “skipped beat,” flutter, or pause is medically described as a palpitation, resulting from the heart’s recovery from mechanical stress. When the high intrathoracic pressure is relieved, the veins and heart chambers rapidly fill with the blood that was momentarily held back. This sudden influx causes the heart to contract with greater force to quickly restore normal circulation, resulting in a hard, noticeable beat. This powerful beat, immediately following the period of reduced output, is often perceived as the heart “restarting” after a pause.
The rapid change in blood pressure and heart rate can also stimulate the vagus nerve, which influences heart rhythm and the cough reflex, contributing to the sensation of an irregular beat. In rare cases, the temporary lack of blood flow to the brain due to severely reduced cardiac output can lead to a brief loss of consciousness, known as cough syncope. While alarming, this is an uncommon consequence of particularly strenuous coughing fits.