The first observations on the carotid sinus reflex were by Parry, 167 who noted dizziness and slowing of the heart following pressure on the bifurcation of the common carotid artery. Mechanical stimulation of the carotid body by massage normally causes only a small fall in heart rate and in blood pressure.
A hypersensitive carotid sinus reflex is defined by a slowing in heart rate of more than 50 percent or a decline in systolic pressure by more than 40 mmHg during carotid sinus massage. 83 However, less than 50 percent of patients with carotid hypersensitivity have syncope as a result.
The mechanics behind this are simple: If the Carotid Sinus senses high blood pressure, it stimulates the corresponding brain canter to slow the heart down, at least until the blood pressure comes down.
In patients with cardioinhibitory carotid sinus syndrome, more than 70% have a positive response to right-sided carotid sinus massage either alone or in combination with left-sided carotid sinus massage. There is no fixed relationship between the degree of heart rate slowing and the degree of fall in blood pressure.
A baroreceptor is a type of mechanoreceptor in the human body that is sensitive to pressure changes, enacting an appropriate response to these changes to keep the body at homeostasis.
The carotid sinus is a dilation at the base of the internal carotid artery. The nearby carotid body is a fibrous-covered structure that rests posteriorly to the carotid bifurcation. The blood supply to carotid sinus is by the vasa vasorum vessels.
B)The carotid sinus reflex helps to regulate blood pressure in the brain while the aortic reflex regulates systemic blood pressure.
The carotid sinus is located where the common carotid artery bifurcates into the internal and external carotid artery at C4.
In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the "true" internal carotid artery.
The carotid sinus is a thin-walled dilatation located at the proximal end of the internal carotid artery just above the bifurcation of the common carotid artery into the internal and external carotid artery.
The carotid sinus usually appears as a dilation of the lower end of the internal carotid in late adolescence (Seong et al 2005) and functions as a baroreceptor. The carotid body is a reddish-brown, oval structure, 5–7 mm in height and 2.5–4 mm in width.
HistoryRecurrent dizziness, near-syncope.Recurrent syncope.Nonaccidental, unexplained falls.Symptoms produced by head turning or wearing garments with tight-fitting collars.Neck tumors, extensive neck scarring secondary to radical dissection or radiation fibrosis or neck trauma.More items...•
d. when sitting up from a supine position the carotid arteries vasodilate when sitting up from a supine position
A physician writes a medication order for D10W. The drop factor is set to 60 gtt/mL and the flow rate is 50 mL/hr. How many liters of fluid would be r … equired to fill this order for 1 day? Use dimensional analysis/stoichiometry to solve.
The carotid sinus reflex protects the blood supply to the brain, whereas the aortic reflex is more concerned with maintaining adequate blood pressure in the systemic circuit as a whole.
The adjustment of blood flow to each tissue in proportion to its requirements at any point in time is termed autoregulation.
Osmotic pressure is created by the presence in a fluid of small diffusible molecules that easily move through the capillary wall.
The aorta's tunica media is thick with dense regular connective tissue to withstand the blood's pressure.
These capillaries may be lined with phagocytes that can extend their process into the plasma to catch "prey."
The carotids are two large arteries that run from your heart up the middle part of the neck to the brain, supplying the neck and head with oxygenated blood; one on the left and one the right side of the body .
The Carotid Sinus is under the control of the autonomic nervous system (ANS) and consists of various nerve receptors for baroregulation (pressure regulation of the body), making it sensitive to pressure changes in the arterial blood at this level, caused both by internal (medical) and external (manual stimulation) triggers.
The mechanics behind this are simple: If the Carotid Sinus senses high blood pressure, it stimulates the corresponding brain canter to slow the heart down, at least until the blood pressure comes down.
This has the following effect (reflex): The disturbance in normal heart function (bradycardia), decreases blood flow to the brain, which causes hypoxia -diminished oxygen availability to the brain.
Its primary objective is maintaining blood pressure and regulating blood flow to the brain, but has the ability to cause severe and/or lethal effects to the body, due to its high sensitivity ; symptoms include cardiac arrhythmia and cardiac arrest.
The first observations on the carotid sinus reflex were by Parry, 167 who noted dizziness and slowing of the heart following pressure on the bifurcation of the common carotid artery. Mechanical stimulation of the carotid body by massage normally causes only a small fall in heart rate and in blood pressure.
Modulating autonomic tone by carotid sinus massage during the physical examination can be useful to expose the patient with the hypersensitive carotid sinus reflex. The clinician first needs to listen carefully over both carotids to be certain that no bruit is present, palpate lightly to determine that a normal carotid pulse is present, and then gently depress or rub the carotid sinus. Gentle massage for approximately 10 to 15 seconds or less usually is all that is necessary to produce significant periods of sinus arrest or AV block in susceptible patients.
The recommended duration of carotid sinus massage is from 5 to 10 seconds. The maximum fall in heart rate usually occurs within 5 seconds ...
Complications resulting from carotid sinus massage include cardiac arrhythmias and neurologic sequelae. Fatal arrhythmias are extremely uncommon and have generally only occurred in patients with underlying heart disease undergoing therapeutic rather than diagnostic massage.
Symptom reproduction during carotid sinus massage is preferable for a diagnosis of carotid sinus syndrome. Symptoms reproduction may not be possible for older patients with amnesia for loss of consciousness. Spontaneous symptoms usually occur in the upright position. It may thus be worth repeating the procedure, with the patient upright on a tilt table, even after demonstrating a positive response when supine. This reproduction of symptoms aids in attributing the episodes to carotid sinus hypersensitivity, especially in patients with unexplained falls who deny loss of consciousness. In one third of patients, a diagnostic response is only achieved during upright carotid sinus massage.
There is no fixed relationship between the degree of heart rate slowing and the degree of fall in blood pressure.
Digoxin toxicity has been implicated in most cases of ventricular fibrillation. Neurologic complications result from either occlusion of, or embolization from, the carotid artery. Several authors have reported cases of hemiplegia following carotid sinus stimulation, often in the absence of hemodynamic changes.
The carotid sinus is at the origin of the internal carotid artery. In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage.
Massage. Massage of the carotid sinus, carotid sinus massage is used to diagnose carotid sinus syncope and is sometimes useful for differentiating supraventricular tachycardia (SVT) from ventricular tachycardia.
Carotid sinus syndrome is a temporary loss of consciousness that sometimes accompanies convulsive seizures because of the intensity of the carotid sinus reflex when pressure builds in one or both carotid sinuses.
Treatment of resistant hypertension. Stimulation of baroreceptors at the carotid sinus can be used to treat resistant hypertension via activation of the baroreflex. A pacemaker-like device can be implanted to electrically stimulate the receptors chronically, which is found to lower blood pressure by 15–25 mmHg.
Carotid sinus reflex death is a potential etiology of sudden death in which manual stimulation of the carotid sinus allegedly causes strong glossopharyngeal nerve ( Vagus nerve is for aortic arch baroreceptors) impulses leading to terminal cardiac arrest.
The carotid sinus often has atherosclerotic plaques because of disturbed hemodynamics (low wall shear stress, flow reversal/recirculation). Since these plaques, if large and unstable, predispose to ischemic strokes and transient ischemic attacks, carotid endarterectomies are frequently done for prophylaxis .
Stimulation of the carotid sinus via a slap or a strike, to induce (usually temporary, but sometimes lethal) loss of consciousness is a self-defense technique , and is often taught in martial arts such as karate.