A7- Syncope Flashcards
WHat is syncope?
the suddent transient loss of consciousness and postural tone with spontaneous recovery.
Loss of consciousness occurs within 10 secinfd of hypoperfusion of the reticular activating system in the mid brain.
What is presyncope? Symptoms?
What is another name for presyncope?
Pre-syncope is the feeling that you are about to faint. Someone with pre-syncope may be lightheaded (dizzy) or nauseated, have a visual “gray out” or trouble hearing, have palpitations, or feel weak or suddenly sweaty. When discussing syncope with your doctor, you should note episodes of pre-syncope as well.
Symptoms include: dizziness, lightheadedness or faintness, weakness, fatigue, and visual and auditory disturbances
Syncopal prodrome
______ causes of syncope have the highest mortality rates
Cardiac causes of syncope have the highest mortality rates
How can syncope impact someones life
Cause anxiety/Depression
Alter Faily Activities
Restricted Driving
Change Employment
Explain the maintenance postural Normal tension
When standing there is a pooling of 500-1000mL of blood in the lower extremities and slanchi circulation.
There is a decrease in venous return to the heart and reduced ventricular filling that result in diminished cardiac output and blood
These haemodynamic changes provoke a compensatory reflex response, initiated by the baroreceptors in the carotid sinus and aortic arch, resulting in increased sympathetic outflow and decreased vagal nerve activity
The reflex increases peripheral resistance, venous return to the heart, and cardiac output and thus limits the fall in blood pressure
Syncope causes can be split into 5 groups.
What are they?
Neurally-Mediated
Orthostatic
Cardiac Arrhythmia
Structural Cardio-Pulmonary
Non Cardio-Vascular
Example of Neurally mediated syncope causes?
Vasovaal
Carotid Sinus
Situational
- Cough
- Post-Micturition
Example of Orthostatic syncope causes?
Drug induced
ANS Failure: Primary or Secondary
Brady: Sick Sinus, AV Block
Tachy: VT, SVT
Long QT Syndrome
Example of Structural Cardio-Pulmonary syncope causes?
Aortic Stenosis
HOCM
Pulmonary Hypertension
Example of Non-Cardio Vascular syncope causes?
Psychogrnic
Metabolic eg hyper-ventilation
Neurological
What are some causes of syncope in a younger patients?
Vasovagal
Situational
Psychiatric
Long OQ
Brugada Syndrome
WPW syndrom
RV
Dysplasia
Hypertophic Cardiomyopathy
Catecholamnergic VT
Other genetic syndromes
What are some causes of syncope in a older patients?
Cardiac: Mechanical, Arrhythmic
Orthostatic hypotension
Drug induced
Neurally mediated
Mutifactorial
What is Cardiac Syncope?
Severe obstruction to cardiac output or rhythmn disturbace can lead to syncope
a) due to strucural abnormalites leading to flow: exertional syncope is a common mindeststion of all types of heart diseae in which cardiac output is fixed an ddoes not rise or may fall with exercise
b) LVOTO: common conditiona AS,HCM
Syncope occurs in what percentage of people with aortic stenosis?
<42%
What is the mechanism of syncope for people with aortic stenosis?
Due to fixed CO, CO Decreases on exertion due to reflex fall in perioheral vascular resistance
30 % Hypertophic cardiomyopathy patients have syncope
Explain its mechanism
Dynamic LVOTO is worsened by an increase in LV contractility (stinulatin the LV mechanoreceptors), decrease in chamber size, or decrease in after-load.. (Hence, a Valsalva maneuver, severe cough or drugs precipitates hypotension and syncope.
How does RVOTO cause syncope?
inability to incrase CO in association with a reflec fall of peripheral resistance results in hypotension and syncope
How does CAD cause syncope?
sudden pump failure producing hypotension and decreased perfusion of the brain
What is the common arrhythmia that causes syncope?
Ventricular tachycardia?
What is the normal response to upright position (standing):
The decrease in venous return, stroke volume and arterial pressure lead to increase sympathetic and decrease parasympathetic activity, thereby maintain BP and heart rate
Patho of vasovagal syncope
In vasovagal syncope: facilitating factors teigger baroreceptors and medullary centes through afferent fibres, activating the parasympathetic tone but inhibiting the sympathetic tone through vagal efferent fibres resulting in hypotesion and bradycardia and there by syncopy.
Neurally mediated syncope can be caused following a _______ ___________
what does this mean
Cardiac catheterisation
Pain associated with femoral puncture and groin compression after sheath removal may produced vasivagal episode and result in syncope.
What is micturational syncope?
What sub category does it fit in?
Often seen in younger men after rising from the bed in early morning and men who with sudden LOC during or immediately following voiding .
Situational Syncope
Mechanism of situation syncope?
Name some predisposing factors
SImilar ot vasogal, the mechanoreceptors in bladder are triggered in the oresence of predisposing factors causing syncope
Predisposing factorsL fatigue, decreased food intake, alcohol ingestion, recent UTI , bladder pathology.
Defecation syncope
Mechanism
Predisposing factors
Facilitating factors
Mechanism: Triggering of mechanoreceptors in th egut wall in the presence of predisposing and facilitating factors
Predisposing factors: Fatigue, decreased food intak , alcohol consumption, GIT pathology
Facilitating factors: Change in the sleep, valsalva manuever during defecation, orthostatic hypotension
Cough syncope can also be known as
tussive/ post tussive laryngeal vertigo
Who usually experiences cough syncope
middle aged men who drink alcohol, smoke and have a chronic lung disease
What receptors are triggered in cough syncope?
Pulmonary mechanoreceptors
severe coughing increases intrathoracic pressure which deceases venous return and in turn CO
Transmission of high intrathoracic oressur eto the subarachnoid space during coughin may increase the cerebrovascular resistance and reduce the cerebral blood flow.
Mechanism of carotid sinus hypersensitivity
Triggering of carotid sinu s(located in the ICA just above the bifurcation of CCA) and medullary centres via afferent fibres (glossopharyngeal and vagus nerves) activates parasympathetic and inhibits sympathetic tone via vagal and sympathetic efferent fibres results in profund bradycardia and hypotension
Which type of people have Carotid sinus hypersensitivity?
asymptomatic elder males
Defecation syncope most occurs in
elders, sually arising dro m bed at night or during manual disimpaction of the rectum.
What are the 3 types of carotid sinus hypersensitivity and explain them?
What is orthostatic syncope?
A decline of >20mmhg in systilic or >10mmhg in diastolic BP upon assuming upright posture is often defined as orthosatic hypotension
It is a disorder in which assumption of upright oosture results hypotension assocuated with light headness blurring of vision and sense of profound weakness
What blood supply is affected in neurological syncope?
Vertebrobasilar system
Subclavian artery
12-18% of patiets with migraine may have syncope and orthostatic hypotension due to hyperresponsiveness of _______ receptors with the inhibition of _______ centre and _______ reaction secondary to pain
12-18% of patiets with migraine may have syncope and orthostatic hypotension due to hyperresponsiveness of dopamine receptors with the inhibition of vasomotor centre and vasovagal reaction secondary to pain
Migraine related syncope is usually seen in what type of people
young women and has a strong menstrual association
What to ask for a history of syncope?
Mode of onset
Duration of episode
Precipitating factors (triggers)
Associated factors- before (prodromes, aura), during and after (postictal)
Predisposing factors
Family history
What do you specifically ask in family history for syncope
fhx of epilepsy may be present in seizures
postive family history in HOCM, long QT syndrome
What is the difference between Seizure and Syncope
onset
duration
jerks
headache
confusion after
incontinence
eye deviation
tongue biting
prodrome
EEG
What blood pressure measurements should be obtained during presentation of syncope
BP measurement for detection of orthostatic hypotension: supine BP and heart rate measured after patient has been lying down for at least for 5 mins
Standing measurements should be obtained immediately and for at least 2 min and should be continues for 10 min when there is a high suspicion of orthostatic hypotension
What are some heart monitoring options
12- lead
holter monitor
Event Recorders
What is Carotid sinus massage
Method is to massage for 5-10 seconds in a supin and upright posture
What is head up tilt test HUTT
Tx for syncope
principal goals of treatnent:
- prevent recurrences
- reduce risk of mortality
- prevent injuries associated with recurrences
- imprive quality life
Tx of cardiac arrhythmias as primary cause
- prevention of symptom recurrence
- improvement of quailty of work- reduction of mortality risk
What is the first line therapy for treament of syncope AV block (1 and B)
Cardiac pacing
Tx for orthostatic hypoT
Class 1 recommendation
Syncope due to orthostatic hypotension should be treated in all patients. In many instances treatment entails only modification of drug treatment for concomitant conditons
Management of Neurogenic Orthoststic HypoT
Management of Neurogenic Orthostatic Hypotension
drugs
Midodrine: α‐1‐adrenoceptor agonist that constricts arteriolar and venous vasculature producing an increase in BP. SH is common with midodrine. Dose: start at 2.5mg bd/tds; max: 10mg tds
• Droxidopa: licenced in USA (L‐threo‐3,4‐dihydroxyphenyl‐serine) or L‐DOPS is a synthetic amino acid, which, after oral administration, is converted to the naturally occurring sympathetic neurotransmitter norepinephrine. Patients with NOH retain the ability to convert droxidopa into norepinephrine and thereby increase their BP.
• Fludrocortisone: mimics the action of aldosterone and raises BP
