Cardiac Reflex: From 1 Different Sources
reflex control of the heart rate. Sensory fibres in the walls of the heart are stimulated when the heart rate increases above normal. Impulses are sent to the cardiac centre in the brain, stimulating the vagus nerve and leading to slowing of the heart rate.
Absence of a palpable pulse, and thus of circula tion of blood around the body by the heart contraction. The cause may be asystole or ventricular fibrillation.... cardiac arrest
Relating to the heart... cardiac
The volume of blood pumped out per minute by the ventricles of the heart. It is one measure of the heart’s e?ciency. At rest, the heart of a healthy adult will pump between 2.5 and 4.5 litres of blood every minute. Exercise will raise this to as much as 30 litres a minute but, if this ?gure is low, it suggests that the heart muscle may be diseased or that the person has suffered severe blood loss.... cardiac output
Drugs whose main actions are to increase the force of myocardial contraction and reduce the conductivity of the nerve ?bres in the atrioventricular node of the heart. They are useful in treating supraventricular tachycardias (rapid heart rhythm) and some forms of heart failure. Glycosides are a traditional group of cardiac drugs, originally derived from the leaves of foxglove plants and used as digitalis. The active principle has long been synthesised and used as DIGOXIN. They are potentaially toxic and their use, especially during initial treatment, should be monitored. Side-effects include ANOREXIA, nausea, vomiting, diarrhoea and abdominal pain; drowsiness, confusion and DEPRESSION may occur. An abnormally slow heart rate may develop. The glycosides should be used with special care in the elderly who are sometimes particularly susceptible to their toxic effects.... cardiac glycosides
The procedure used to restart the action of the heart if it is suddenly arrested. In many cases the arrested heart can be made to start beating again by rhythmic compression of the chest wall. This is done by placing the patient on a hard surface – a table or the ?oor – and then placing the heel of the hand over the lower part of the sternum and compressing the chest wall ?rmly, but not too forcibly, at the rate of 60–80 times a minute. At the same time arti?cial respiration must be started by the mouth-tomouth method. (See APPENDIX 1: BASIC FIRST AID.) Open heart massage is sometimes undertaken if an arrest occurs during a chest operation – the heart being directly handled by the resuscitator.... cardiac massage
The muscle, unique to the heart, which comprises the walls of the atria and ventricles. It consists of long broadening cells (?bres) with special physiological characteristics which enable them to keep contracting and expanding inde?nitely.... cardiac muscle
Obsessional fear about the state of the heart. It tends to occur after a heart attack and may result in the patient’s experiencing the symptoms of another attack.... cardiac neurosis
Compression of the heart due to abnormal accumulation of ?uid within the ?brous covering of the heart (PERICARDIUM). The result is irregular rhythm and death if the ?uid is not removed.... cardiac tamponade
A form of complementary medicine in which the practitioner massages parts of the patient’s feet in an attempt to treat disorders affecting other areas of the body.... reflexology
When a sharp body is drawn along the sole of the foot, instead of the toes bending down towards the sole as usual, the great toe is turned upwards and the other toes tend to spread apart. After the age of about two years, the presence of this re?ex indicates some severe disturbance in the upper part of the central nervous system. The Babinski re?ex may occur transiently during COMA or after an epileptic ?t and need not indicate permanent damage.... babinski reflex
Abnormal rhythm of the heartbeat. Most commonly seen after someone has had a myocardial infarction, but also present in some normal individuals – especially if they have taken a lot of co?ee or other stimulant – and in those with a congenital abnormality of the heart-muscle conducting system. The cause is interference in the generation or transmission of electrical impulses through the heart’s conducting system. Occasional isolated irregular beats (ectopic beats) do not necessarily mean that conduction is faulty. Arrhythmias can be classi?ed as tachycardias (more than 100 beats a minute) or bradycardias (slower than 60 beats a minute). Heartbeats may be regular or irregular. (See HEART, DISEASES OF.)... cardiac arrhythmia
A diagnostic procedure in which a tube is inserted into a blood vessel under local anaesthetic and threaded through to the chambers of the heart to monitor blood ?ow, blood pressure, blood chemistry and the output of the heart, and to take a sample of heart tissue. The technique is used to diagnose congenital heart disease and coronary artery disease. Another application is in the diagnosis and treatment of valvular disease in the heart.... cardiac catheterisation
Slowing the action of the heart... cardiac depressant
See HEART, ARTIFICIAL.... cardiac pump
The development of a speci?c response by an individual to a speci?c stimulus. The best-known conditioned re?ex is the one described by Ivan Pavlov, in which dogs that became accustomed to being fed when a bell was sounded salivated on hearing the bell, even if no food was given. The conditioned re?ex is an important part of behavioural theory.... conditioned reflex
Instinctive closing of the eyelids when the surface of the cornea (see EYE) is lightly touched with a ?ne hair.... corneal reflex
A cough induced by intestinal, gastric or uterine irritation, and not from respiratory causes.... cough, reflex
Compression of the outside of the sternum and ribs, effectively emptying and filling the heart to push blood through arteries to supply oxygen to the body - particularly to the brain.... external cardiac compression
Assessment of victims of major trauma must include maintenance of their airways and breathing. Any false teeth, vomitus and foreign bodies should be removed, and the response to digital stimulation of the posterior pharyngeal wall – the ‘gag re?ex’ – assessed. Even with a normal gag re?ex, the airway may be seriously threatened if vomiting occurs. During the initial stages of resuscitation, careful and constant supervision of the airway is essential, with a high-volume sucker immediately available. If the gag re?ex is absent or impaired, an endotracheal tube should be inserted (see ENDOTRACHEAL INTUBATION).... gag reflex
A ‘protective’ cough occurring as a result of irritation of the LARYNX – for example, a small particle of food may be accidentally ‘inhaled’ into the larynx, which reacts with an expulsive cough to prevent the food from entering the lungs.... laryngeal reflex
Pupillary constriction in the EYE in response to light. The direct light re?ex involves pupillary constriction in the eye into which a light is shone; the consensual light re?ex is the pupillary constriction that occurs in the other eye. The a?erent or inward pathway of the re?ex is via the optic nerve, and the e?erent or outward pathway is via the occulomotor nerve.... light reflex
A primitive REFLEX ACTION occurring in newly born infants in response to a sudden movement or noise. Also known as the startle re?ex, the baby will throw its arms and legs wide and sti?en its body. This is followed by ?exion of the arms and legs. The re?ex disappears by four months; its persistence suggests a possible neurological condition such as CEREBRAL PALSY.... moro reflex
See REFLEX ACTION.... patellar reflex
Eye movement that occurs after or during the slow injection of 20 ml of ice-cold water into each external auditory meatus (see EAR) in turn.... vestibulo-ocular reflex
Breathing difficulty in which bronchospasm and wheezing are caused by accumulation of fluid in the lungs (pulmonary oedema). This is usually due to reduced pumping efficiency of the left side of the heart (see heart failure) and is not true asthma. Treatment is with diuretic drugs.... asthma, cardiac
One of a group of tests used to assess the function of the heart in people who experience chest pain, breathlessness, or palpitations during exercise. The test establishes whether the patient has coronary artery disease. An ECG machine records the patterns of the heart’s electrical activity while the heart is stressed. This is usually achieved by the patient exercising on a treadmill or cycling. Specific changes in the electrical pattern as exercise levels increase indicate angina. Cardiac stress testing may be used in conjunction with radionuclide scanning to identify damaged areas of heart muscle.... cardiac stress test
A diagnostic test in which a fine, sterile catheter is introduced into the heart via a blood vessel. It is used to diagnose and assess the extent of congenital heart disease (see heart disease, congenital) and coronary artery disease, and to diagnose and treat some disorders of the heart valves (see valvuloplasty). During the procedure, the pressure within the heart’s chambers can be measured, samples of blood and tissue can be taken, and a radiopaque substance can be injected to allow the heart’s cavities to be X-rayed.... catheterization, cardiac
A medical term meaning disturbance of heart rhythm, sometimes used as an alternative to arrhythmia (see arrhythmia, cardiac).... dysrhythmia, cardiac
Dropsy of heart origin is distinguished from renal dropsy by an increase in oedema as the day proceeds. In the morning there may be no swelling but by the evening legs become swollen from the ankles upwards. Fluids stagnate in the tissues from inability of the heart to perform efficiently as a pump. The condition is a symptom of heart failure with increasing breathlessness which may lead to general dropsy.
Symptoms: worse after exercise, breathlessness, headache, general weakness, feeble pulse, pale face, skin cold, swollen tissues pit on pressure.
Treatment. Alternatives:– Teas. Black Cohosh, Broom tops, Buchu, Dandelion, Hawthorn, Parsley root. Tea. Formula. Equal parts: Broom tops, Motherwort, Yarrow. 2 teaspoons to each cup water brought to boil and simmered 5 minutes in covered vessel. 1 cup 3-4 times daily.
Tablets/capsules. Buchu, Dandelion, Hawthorn, Juniper, Motherwort.
Formula. Dandelion 2; Hawthorn 2; Stone root 1. Mix. Dose: Powders: 750mg (three 00 capsules or half a teaspoon). Liquid extracts: 1 teaspoon. Tinctures: 2 teaspoons. Thrice daily.
Practitioner. Lily of the Valley, BPC 1934: 5-20 drops, 2-3 times daily.
Squills, tincture: resembles Digitalis in action. Dose: 1-3 drops, as prescribed.
Tinctures. Dandelion 2; Lily of the Valley 2; Stone root 1; Cayenne (tincture) quarter. Mix. Dose: 1 to 2 teaspoons thrice daily.
Popular formula. Tincture Scilla 5.0; Tincture Crataegus 10.0; Tincture Valerian to make 30.0. 15 drops thrice daily. (German Extemporaneous Formulae)
Diet. High protein. See: DIET – HEART AND CIRCULATION. ... cardiac dropsy
An abnormality of the rhythm or rate of the heartbeat. Arrhythmias, which are caused by a disturbance in the electrical impulses in the heart, can be divided into 2 main groups: tachycardias, in which the rate is faster than normal, and bradycardias, in which the rate is slower.
In sinus tachycardia, the rate is raised, the rhythm is regular, and the beat originates in the sinoatrial node (see pacemaker). Supraventricular tachycardia is faster and the rhythm is regular. It may be caused by an abnormal electrical pathway that allows an impulse to
circulate continuously in the heart and take over from the sinoatrial node. Rapid, irregular beats that originate in the ventricles are called ventricular tachycardia. In atrial flutter, the atria (see atrium) beat regularly and very rapidly, but not every impulse reaches the ventricles, which beat at a slower rate. Uncoordinated, fast beating of the atria is called atrial fibrillation and produces totally irregular ventricular beats. Ventricular fibrillation is a form of cardiac arrest in which the ventricles twitch very rapidly in a disorganized manner.
Sinus bradycardia is a slow, regular beat. In heart block, the conduction of electrical impulses through the heart muscle is partially or completely blocked, leading to a slow, irregular heartbeat. Periods of bradycardia may alternate with periods of tachycardia due to a fault in impulse generation (see sick sinus syndrome).
A common cause of arrhythmia is coronary artery disease, particularly after myocardial infarction. Some tachycardias are due to a congenital defect in the heart’s conducting system. Caffeine can cause tachycardia in some people. Amitriptyline and some other antidepressant drugs can cause serious arrhythmias if they are taken in high doses.
An arrhythmia may be felt as palpitations, but in some cases arrhythmias can cause fainting, dizziness, chest pain, and breathlessness, which may be the 1st symptoms.
Arrhythmias are diagnosed by an ECG. If they are intermittent, a continuous recording may need to be made using an ambulatory ECG.
Treatments for arrhythmias include antiarrhythmic drugs, which prevent or slow tachycardias.
With an arrhythmia that has developed suddenly, it may be possible to restore normal heart rhythm by using electric shock to the heart (see defibrillation).
Abnormal conduction pathways in the heart can be treated using radio frequency ablation during cardiac catheterization (see catheterization, cardiac).
In some cases, a pacemaker can be fitted to restore normal heartbeat by overriding the heart’s abnormal rhythm.... arrhythmia, cardiac
An automatic movement in response to a stimulus that is present in newborn infants but disappears during the first few months after birth. Primitive reflexes are believed to represent actions that were important in earlier stages of human evolution. They include the grasp reflex when something is placed in the hand and the rooting reflex, which enables a baby to find the nipple. The rooting reflex can be evoked by touching the baby’s cheek with the fingertip. These reflexes are tested after birth to give an indication of the condition of the nervous system.... reflex, primitive
(convergence reflex) a reflex that occurs when an individual focuses on a near object, in which the crystalline lens becomes more convex, the pupils constrict, and the eyes turn inwards.... accommodation reflex
a primitive reflex that is present from birth but should disappear by six months of age. If the infant is lying on its back and the head is turned to one side, the arm and leg on the side to which the head is turned should straighten, and the arm and leg on the opposite side should bend (the ‘fencer’ position). Persistence of the reflex beyond six months is suggestive of *cerebral palsy.... asymmetric tonic neck reflex
see plantar reflex. [J. F. F. Babinski (1857–1932), French neurologist]... babinski reflex
a form of education in resuscitation skills using a *resuscitation mannikin wired up to a heart rhythm simulator that can mimic all common cardiac arrest situations. Candidates may be expected to perform basic life support as well as advanced life support and display skills in airway maintenance and team leadership. This form of teaching and assessment is widely used in advanced life support courses.... cardiac arrest simulation
a designated team of doctors in a hospital who attend *cardiac arrests as they occur and administer protocol-driven treatment according to the latest guidelines. See also medical emergency team.... cardiac-arrest team
the volume of blood pumped from the heart’s left ventricle divided by body surface area, expressed as litres per minute per square metre (l/min/m2). It is determined by heart rate and stroke volume index (the volume of blood pumped by the heart with each beat), and provides a normal range (2.5–4.0 l/min/m2) regardless of the size of the patient.... cardiac index
a programme of staged exercises and lifestyle classes designed for people recovering from a heart attack and run through the local hospital by dedicated health care professionals, who may include specialist nurses, occupational therapists, and physiotherapists.... cardiac rehabilitation
(CRT) a treatment for heart failure that involves ventricular pacing with multiple *leads. The aim is to restore coordinated ventricular contraction and hence improve cardiac function.... cardiac resynchronization therapy
a reflex in which the response occurs not to the sensory stimulus that normally causes it but to a separate stimulus, which has been learnt to be associated with it. In Pavlov’s classic experiments, dogs learned to associate the sound of a bell with feeding time and would salivate at the bell’s sound whether food was then presented to them or not.... conditioned reflex
(CCF, congestive heart failure) see heart failure.... congestive cardiac failure
reflex blinking of both eyes normally elicited by lightly touching the cornea of one eye. This reflex is lost in deep coma, during general anaesthesia, and in death; it is therefore one of the tests used to confirm brainstem death.... corneal reflex
a superficial reflex in males elicited by stroking the inner side of the upper thigh with a sharp object. If the reflex is intact the scrotum on that side is pulled upwards as the cremaster muscle contracts. Absence or reduction of both cremasteric reflexes indicates an upper *motor neuron lesion; absence of the reflex on one side suggests a lower motor neuron lesion at the level of the first lumbar spinal nerve.... cremasteric reflex
see Hoffmann’s sign.... finger-flexion reflex
a reflex action of the body that develops by five to six months and never disappears. If the body is held by the waist face down and lowered, the arms and legs extend automatically.... forward parachute reflex
(pharyngeal reflex) a normal reflex action caused by contraction of pharynx muscles when the soft palate or posterior pharynx is touched. The reflex is used to test the integrity of the *glossopharyngeal and *vagus nerves.... gag reflex
a wave of peristalsis produced in the colon by introducing food into a fasting stomach.... gastrocolic reflex
the relaxation of the *ileocaecal valve caused by the presence of food in the stomach.... gastroileac reflex
involuntary grasping in response to anything that touches the palm of the hand. This is a normal reflex in babies that is lost in early childhood. In adults it is a sign of damage to the *prefrontal lobes of the brain.... grasp reflex
the normal physiological reflex to breathe out when the breath is held in inspiration and to breathe in when it is held in exhalation. [H. E. Hering (1866–1948), German physiologist; J. Breuer (1842–1925), German physician]... hering–breuer reflex
an abnormal reflex elicited by lightly placing the index finger across the chin of the patient and tapping it with a tendon hammer while the jaw hangs loosely open. A brisk upward movement of the jaw indicates an upper *motor neuron disorder above the brainstem.... jaw-jerk reflex
a reflex seen in normal babies from three months until one year, when it disappears. If the baby is held horizontally, face down, it will straighten its legs and back and try to lift up its head. The presence of this reflex beyond one year may be suggestive of a developmental disorder.... landau reflex
a cough produced by irritating the larynx.... laryngeal reflex
see pupillary reflex.... light reflex
involuntary contraction of the stapedius and/or tensor tympani muscles in the middle ear in response to various stimuli. The stapedius contracts in response to sound (see stapedial reflex). The tensor tympani is thought to contract during chewing. The sound-evoked middle ear reflex can be detected using a *tympanometer.... middle ear reflex
(startle reflex) a primitive reflex seen in newborn babies in response to the stimulus of a sudden noise or movement: the baby will fling its arms and legs wide and will appear to stiffen; the arms and legs are then drawn back into flexion. The Moro reflex should disappear spontaneously by four months. Its presence beyond this age is suggestive of an underlying neurological disorder, such as cerebral palsy. [E. Moro (1874–1951), German paediatrician]... moro reflex
a reflex action of the intestine in which a physical stimulus causes the intestine to contract above and relax below the point of stimulation.... myenteric reflex
see stretch reflex.... myotatic reflex
see gag reflex.... pharyngeal reflex
a reflex obtained by drawing a bluntly pointed object (such as a key) along the outer border of the sole of the foot from the heel to the little toe. The normal flexor response is a bunching and downward movement of the toes. An upward movement of the big toe is called an extensor response (or Babinski reflex or response). In all persons over the age of 18 months this is a sensitive indication of damage to the *pyramidal system in either the brain or spinal cord.... plantar reflex
(light reflex) the reflex change in the size of the pupil according to the amount of light entering the eye. Bright light reaching the retina stimulates nerves of the *parasympathetic nervous system, which cause the pupil to contract. In dim light the pupil opens, due to stimulation of the *sympathetic nervous system. See also iris.... pupillary reflex
flexion of the forearm (and sometimes also of the fingers) that occurs when the lower end of the radius is tapped. It is due to contraction of the brachioradialis muscle, which is stimulated by tapping its point of insertion in the radius.... radial reflex
the red area seen through the pupil as a result of the reflection of light from the retina. It is usually seen on *fundoscopy and sometimes in photographs taken using a flashlight.... red reflex
(knee jerk) reflex contraction of the quadriceps (thigh) muscle so that the leg kicks, elicited in a patient sitting with one knee crossed over the other by sharply tapping the tendon of the muscle below the kneecap. The reflex is mediated through nerves emanating from the third and fourth lumbar spinal levels (see spinal nerves). This is a test of the connection between the sensory nerves attached to stretch receptors in the muscle, the spinal cord, and the motor neurons running from the cord to the thigh muscle, all of which are involved in the reflex. The patellar reflex is reduced or absent when there is disease or damage of the spinal cord at or below the level of the reflex and exaggerated in disorders above the level of the reflex.... patellar reflex
the nervous circuit involved in a *reflex, being at its simplest a sensory nerve with a receptor, linked at a synapse in the brain or spinal cord with a motor nerve, which supplies a muscle or gland (see illustration). In a simple reflex (such as the *patellar reflex) only two neurons may be involved, but in other reflexes there may be several *interneurons in the arc.... reflex arc
see complex regional pain syndrome.... reflex sympathetic dystrophy
a primitive reflex present in newborn babies: if the cheek is stroked near the mouth, the infant will turn its head to the same side to suckle.... rooting reflex
reflex contraction of the stapedius muscle in the middle ear, attached to the *stapes bone, in response to loud sounds. This protects the cochlea from noise damage by limiting the amount of sound that is transmitted via the stapes. The reflex can be measured using a *tympanometer.... stapedial reflex
see Moro reflex.... startle reflex
the reflex maintenance of muscular tone for posture.... static reflex
a primitive reflex in newborn babies that should disappear by the age of two months. If the baby is held in a ‘walking’ position with the feet touching the ground, the feet move in a ‘stepping’ manner. Persistence of this reflex beyond two months is suggestive of *cerebral palsy.... stepping reflex
(myotatic reflex) the reflex contraction of a muscle in response to its being stretched.... stretch reflex
the closing of the eyelids when the supraorbital nerve is struck, due to contraction of the muscle surrounding the orbit (orbicularis oculi muscle).... supraorbital reflex
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