Watson's water hammer pulse is a characteristic medical sign first described by Thomas Watson, M.D. in 1844. It is a pulse that is powerfully pulsating, similar in nature to the pounding of a water hammer. This hyperdynamic pulse occurs when an increased amount of blood is pumped with each stroke of the left ventricle, the largest chamber of the heart. There is also a decreased resistance to outflow of the blood, leading to a widening of the range between the highest and lowest numbers of a blood pressure reading, called the pulse pressure. The Corrigan's pulse, named for Sir Dominic Corrigan, M.D., refers to a water hammer pulse that is detected in the carotid artery, whereas a Watson's water hammer pulse pertains to one detected peripherally in an arm or leg.
A pulse is the rhythmic throb of blood flow due to the heartbeat. The pulse can be felt in many sites on the human body. Common sites for checking a pulse include in the neck, at the wrist, on the inside of the elbow, behind the knee, and near the ankle joint. It can also be ascertained by assessing the heartbeats directly using a stethoscope. Both pulse rate and quality reveal the underlying status of the heart and blood vessels.
Systolic and diastolic readings constitute the numerical boundaries of blood pressure. They represent opposite ends of the cardiac cycle and the highest and lowest levels of blood pressure for a given individual. The pulse pressure is an indicator of the force that the heart generates each time it contracts. In healthy adults, the pulse pressure in a seated position is approximately 40, but can rise to 100 during exercise. Some studies indicate that the pulse pressure may be a better prognostic indicator of clinical outcome than either the systolic or the diastolic blood pressure alone.
There are many symptoms associated with water hammer pulse, the most common of which are muscle weakness and fatigue. Other associated symptoms include shortness of breath, lower extremity swelling, and headache. Patient may experience chest pains and palpitations. Cardiac arrhythmia, irregular heartbeat, may occur due to impaired electrical conduction in the heart chambers.
A water hammer pulse is most often associated with a leaking aortic valve. The aortic valve is the valve that normally keeps blood that has been pumped out of the heart from flowing backward into the heart again. Aortic regurgitation or leakage occurs when the valve does not close properly, allowing blood to leak backward through it. As a result, the left ventricle has to pump more blood than usual, with progressive expansion due to the extra workload. The symptoms of aortic regurgitation can range from mild to severe, with some patients having no symptoms for years.
Some physiological conditions can cause water hammer pulse, such as pregnancy, fever, and extreme anxiety. Other medical conditions can cause a widened pulse pressure, including anemia, hypertension, and cirrhosis of the liver. It can also occur with a hyperactive thyroid gland. Abnormal connections between arteries and veins, called fistulas, can also produce this pulse.