Korotkoff sounds are the sounds that medical personnel listen for when they are taking blood pressure using a non-invasive procedure. They are named after Nikolai Korotkov, a Russian physician who discovered them in 1905, [1] when he was working at the Imperial Medical Academy in St. Petersburg, the Russian Empire. [2]
The sounds heard during the measurement of blood pressure are not the same as the heart sounds heard during chest auscultation that are due to vibrations inside the ventricles associated with the snapping shut of the valves. [3] If a stethoscope is placed over the brachial artery in the antecubital fossa in a normal person (without arterial disease), no sound should be audible. As the heart beats, these pulses are transmitted smoothly via laminar (non-turbulent) blood flow throughout the arteries, and no sound is produced. Similarly, if the cuff of a sphygmomanometer is placed around a patient's upper arm and inflated to a pressure above the patient's systolic blood pressure, there will be no sound audible. This is because the pressure in the cuff is high enough such that it completely occludes the blood flow. This is similar to a flexible tube or pipe with fluid in it that is being pinched shut.
If the pressure is dropped to a level equal to that of the patient's systolic blood pressure, the first Korotkoff sound will be heard. As the pressure in the cuff is the same as the pressure produced by the heart, some blood will be able to pass through the upper arm when the pressure in the artery rises during systole. This blood flows in spurts as the pressure in the artery rises above the pressure in the cuff and then drops back down beyond the cuffed region, resulting in turbulence that produces an audible sound.
As the pressure in the cuff is allowed to fall further, thumping sounds continue to be heard as long as the pressure in the cuff is between the systolic and diastolic pressures, as the arterial pressure keeps on rising above and dropping back below the pressure in the cuff.
Eventually, as the pressure in the cuff drops further, the sounds change in quality, then become muted, and finally disappear altogether. This occurs because, as the pressure in the cuff drops below the diastolic blood pressure, the cuff no longer provides any restriction to blood flow allowing the blood flow to become smooth again with no turbulence and thus produce no further audible sound.
It has been suggested that the mechanism of Korotkoff sounds may not be a sound waves at all, but vibrations of the arterial walls that transmits into surrounding tissues, a bit like seismic waves. [4] [5] Others have hypothesized that the Korotkoff sounds are due to cavitation [6]
There are five Korotkoff sounds: [7]
The second and third Korotkoff sounds have no known clinical significance. [8]
In some patients, sounds may disappear altogether for a short time between Phase II and III, which is referred to as auscultatory gap.
Traditionally, the systolic blood pressure is taken to be the pressure at which the first Korotkoff sound is first heard and the diastolic blood pressure is the pressure at which the fourth Korotkoff sound is just barely audible. However, there has recently been a move towards the use of the fifth Korotkoff sound (i.e. silence) as the diastolic blood pressure, as this has been felt to be more reproducible. [9]
For paediatrics, there has been controversy regarding whether to use auscultation of the fourth or fifth Korotkoff sound as an indicator of diastolic pressure. Current clinical practice guidelines recommend using the fifth Korotkoff sound (but if this is undetectable, using the fourth). [10] [11]
The time average of the first Korotkoff sound represents a reliable pressure marker of systole of the heart. The time average of the fourth Korotkoff sound represents a reliable pressure marker of diastole of the heart.
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the neck, wrist, at the groin, behind the knee, near the ankle joint, and on foot. Pulse is equivalent to measuring the heart rate. The heart rate can also be measured by listening to the heart beat by auscultation, traditionally using a stethoscope and counting it for a minute. The radial pulse is commonly measured using three fingers. This has a reason: the finger closest to the heart is used to occlude the pulse pressure, the middle finger is used get a crude estimate of the blood pressure, and the finger most distal to the heart is used to nullify the effect of the ulnar pulse as the two arteries are connected via the palmar arches. The study of the pulse is known as sphygmology.
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure in the cardiac cycle. It is measured in millimeters of mercury (mmHg) above the surrounding atmospheric pressure, or in kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure.
Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart.
Heart murmurs are unique heart sounds produced when blood flows across a heart valve or blood vessel. This occurs when turbulent blood flow creates a sound loud enough to hear with a stethoscope. Turbulent blood flow is not smooth. The sound differs from normal heart sounds by their characteristics. For example, heart murmurs may have a distinct pitch, duration and timing. The major way health care providers examine the heart on physical exam is heart auscultation; another clinical technique is palpation, which can detect by touch when such turbulence causes the vibrations called cardiac thrill. A murmur is a sign found during the cardiac exam. Murmurs are of various types and are important in the detection of cardiac and valvular pathologies.
A sphygmomanometer, also known as a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury or aneroid manometer to measure the pressure. Manual sphygmomanometers are used with a stethoscope when using the auscultatory technique.
Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Healthy pulse pressure is around 40 mmHg. A pulse pressure that is consistently 60 mmHg or greater is likely to be associated with disease, and a pulse pressure of 50 mmHg or more increases the risk of cardiovascular disease. Pulse pressure is considered low if it is less than 25% of the systolic. A very low pulse pressure can be a symptom of disorders such as congestive heart failure.
Afterload is the pressure that the heart must work against to eject blood during systole. Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively. Afterload changes to adapt to the continually changing demands on an animal's cardiovascular system. Afterload is proportional to mean systolic blood pressure and is measured in millimeters of mercury.
Diastole is the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventricular diastole the relaxing of the ventricles.
Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a consequence, the cardiac muscle is forced to work harder than normal.
In medicine, the mean arterial pressure (MAP) is an average calculated blood pressure in an individual during a single cardiac cycle. Although methods of estimating MAP vary, a common calculation is to take one-third of the pulse pressure, and add that amount to the diastolic pressure. A normal MAP is about 90 mmHg.
Nikolai Sergeyevich Korotkov, also Korotkoff(Russian: Никола́й Серге́евич Коротко́в; 26 February [O.S. 14 February] 1874 – 14 March 1920) was a Russian surgeon, a pioneer of 20th-century vascular surgery, and the inventor of auscultatory technique for blood pressure measurement.
Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. Pulsus paradoxus is not related to pulse rate or heart rate, and it is not a paradoxical rise in systolic pressure. Normally, blood pressure drops less precipitously than 10 mmHg during inhalation. Pulsus paradoxus is a sign that is indicative of several conditions most commonly pericardial effusion.
An auscultatory gap, also known as the silent gap, is a period of diminished or absent Korotkoff sounds during the manual measurement of blood pressure. It is associated with reduced peripheral blood flow caused by changes in the pulse wave. The improper interpretation of this gap may lead to blood pressure monitoring errors, such as an underestimation of systolic blood pressure and/or an overestimation of diastolic blood pressure. In order to correct for an auscultatory gap, the radial pulse should be monitored by palpation. It is therefore recommended to palpate and auscultate when manually recording a patient's blood pressure. Typically, the blood pressure obtained via palpation is around 10 mmHg lower than the pressure obtained via auscultation. In general, the examiner can avoid being confused by an auscultatory gap by always inflating a blood pressure cuff to 20-40 mmHg higher than the pressure required to occlude the brachial pulse.
In medicine, systolic hypertension is defined as an elevated systolic blood pressure (SBP). If the systolic blood pressure is elevated (>140) with a normal (<90) diastolic blood pressure (DBP), it is called isolated systolic hypertension. Eighty percent of people with systolic hypertension are over the age of 65 years old. Isolated systolic hypertension is a specific type of widened pulse pressure.
Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis.
The cardiovascular examination is a portion of the physical examination that involves evaluation of the cardiovascular system. The exact contents of the examination will vary depending on the presenting complaint but a complete examination will involve the heart, lungs, belly and the blood vessels.
Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the left ventricle is maximally filled – is normal, defined as greater than 50%; this may be measured by echocardiography or cardiac catheterization. Approximately half of people with heart failure have preserved ejection fraction, while the other half have a reduction in ejection fraction, called heart failure with reduced ejection fraction (HFrEF).
The article reviews the evolution of continuous noninvasive arterial pressure measurement (CNAP). The historical gap between ease of use, but intermittent upper arm instruments and bulky, but continuous “pulse writers” (sphygmographs) is discussed starting with the first efforts to measure pulse, published by Jules Harrison in 1835. Such sphygmographs led a shadowy existence in the past, while Riva Rocci's upper arm blood pressure measurement started its triumphant success over 100 years ago. In recent times, CNAP measurement introduced by Jan Penáz in 1973 enabled the first recording of noninvasive beat-to-beat blood pressure resulting in marketed products such as the Finapres™ device and its successors. Recently, a novel method for CNAP monitoring has been designed for patient monitoring in perioperative, critical and emergency care, where blood pressure needs to be measured repeatedly or even continuously to facilitate the best care for patients.
Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids, and their relative velocity to the probe. By calculating the frequency shift of a particular sample volume, for example, flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized.
Arterial blood pressure is most commonly measured via a sphygmomanometer, which historically used the height of a column of mercury to reflect the circulating pressure. Blood pressure values are generally reported in millimetres of mercury (mmHg), though aneroid and electronic devices do not contain mercury.