Syncope Flashcards
What is the definition of syncope?
Transient loss of consciousness due to inadequate cerebral blood flow.
What are common mimics of syncope that are not true syncope?
Seizures, pseudoseizures, sleep issues, and mechanical falls with subsequent loss of consciousness from head trauma.
What is helpful for ruling out seizure as an etiology for loss of consciousness?
Seizures have a gradual, prolonged period of recovery (with the exception being absence seizure) due to the postical stage.
What are the typical clinical features of syncope?
Transient loss of consciousness lasting ~10 seconds, potentially resulting in a fall or accident. May be preceded by prodromal symptoms (nausea, lightheadedness, weakness, and blurred vision) specific to the etiology.
What is the key component of the workup for syncope?
Detailed history and physical exam, ECG/telemetry, orthostatics, labs for metabolic disturbances, and transthoracic echocardiogram (TTE) if structural heart disease is suspected.
Why is it important to determine if the syncopal event was sudden or gradual?
- Sudden onset points to cardiac or neurological
- Gradual onset points to toxins or metabolic problems
- Vasovagal syncope can be sudden or gradual
How is low-risk syncope managed?
Patients with clear vasovagal syncope and no red flags can be discharged home.
A 22-year-old woman is brought to the office by her mother because “she has been passing out.” The patient’s first episode occurred about a year ago when she split up with her boyfriend. A more recent episode was also provoked by strong emotion. Both episodes were preceded by nausea, light-headedness, weakness, and blurred vision, lasted about a minute, and ended with rapid recovery of consciousness. The patient sustained no significant injuries in either episode. She is concerned because one of her childhood friends passed out and died while playing football. Medical history is otherwise insignificant. The patient takes no medications and does not use alcohol or illicit drugs. She has no family history of early coronary artery disease, cardiomyopathy, or sudden cardiac death. Blood pressure is 110/70 mm Hg while supine and 108/70 mm Hg while standing. Physical examination findings are within normal limits. ECG reveals no abnormalities. Complete blood count and serum chemistries are within normal limits. Which of the following is the best next step in management of this patient?
This patient has experienced recurrent vasovagal syncope, a type of reflex syncope. It is typically triggered by emotional distress, prolonged standing, or painful stimuli, and patients usually experience an autonomic prodrome with nausea, pallor, diaphoresis, or generalized warmth. Spontaneous resolution of the episode occurs within seconds to a few minutes. Patients with vasovagal syncope have an excellent prognosis, and the initial approach is aimed at providing education and reassurance. Patients are advised to avoid triggers and to assume a supine position with raised legs at the onset of prodromal symptoms. In addition, patients may be taught physical counterpressure maneuvers (eg, leg crossing with tensing of muscles, tensing of arm muscles with clenched fists) to improve venous return and cardiac output, and abort an episode of vasovagal syncope during the prodromal phase.
What is the most common cause of syncope?
vasovagal syncope
What causes vasovagal syncope?
Increased parasympathetic outflow leading to transient bradycardia and hypotension, often triggered by emotional stress, pain, fear, or prolonged standing. Neurologic signal initiation in vasovagal syncope is thought to be triggered in the cerebral cortex or within various baroreceptors or mechanoreceptors (eg, cardiopulmonary). The signal is then sent via afferent neuronal pathways to the brainstem’s cardioregulatory center, where some combination of cardioinhibitory response (ie, increased parasympathetic stimulation) and vasodepressor response (ie, decreased sympathetic stimulation) occurs. This leads to decreased heart rate and contractility with peripheral vasodilation, which, in turn, leads to hypotension, decreased cerebral perfusion, and syncope. The classic prodromal symptoms (eg, warmth, nausea, diaphoresis) in vasovagal syncope likely represent early physiologic manifestations of altered autonomic activity.
What are the prodromal symptoms of vasovagal syncope?
Nausea, diaphoresis, warmth, pallor, and a general feeling of unwellness before syncope.
What is a clear-cut indication of vasovagal syncope?
Rapid onset and return to consciousness with no other major red flag symptoms.
How is vasovagal syncope diagnosed?
Diagnosis is clinical. In instances of uncertainty, a tilt table test can be employed.
What is the purpose of tilt-table testing?
Tilt-table testing is used to evaluate unexplained syncope, particularly when vasovagal (neurocardiogenic) syncope or orthostatic hypotension is suspected but not confirmed through history or routine examination.
How is vasovagal syncope managed?
Management includes reassurance and counterpressure maneuvers when prodromal symptoms occur. The initial management of vasovagal syncope is aimed at providing education and reassurance about its benign nature and prognosis and advising patients to avoid potential triggers of syncope. In patients with recurrent episodes, physical counterpressure maneuvers can abort or delay an episode of syncope and are recommended during the prodromal phase.
What are the physical physical counterpressure maneuvers used to abort an episode of vasovagal syncope?
Patients should be taught physical counterpressure maneuvers that includes leg crossing with tensing of muscles, tensing of arm muscles with clenched fists, to improve venous return and cardiac output, and abort an episode of vasovagal syncope.
Physical counterpressure maneuvers used to abort an episode of vasovagal syncope are used during which phase?
during the prodromal phase
Can beta-blockers be helpful in vasovagal syncope?
Beta blockers were once thought to interfere with the neurologic pathways responsible for vasovagal syncope; however, these drugs have shown no benefit in preventing vasovagal syncope in randomized trials and are not recommended.
What is situational syncope, and how is it managed?
Syncope triggered by specific situations (e.g., cough, urination, swallowing). Management includes reassurance; pacing may be required for carotid sinus syncope (stimulation of the carotid sinus from events like putting on a helmet, shaving, or tying a necktie).
What is the pathophysiology of carotid sinus hypersensitivity?
Syncope while shaving most likely has carotid sinus hypersensitivity (CSH). When carotid sinus baroreceptors detect increased blood pressure, the brainstem responds by increasing parasympathetic tone (slows the heart rate) and reducing sympathetic tone (induces vasodilation). In some individuals, especially elderly men, the carotid sinus baroreceptors become overly sensitive to tactile stimulation, triggering an exaggerated vasovagal response with marked peripheral vasodilation (ie, decreased systemic vascular resistance). This can cause a transient reduction in cerebral perfusion that manifests as presyncope (eg, faintness, lightheadedness or syncope. As with other etiologies of syncope, cerebral perfusion quickly returns and symptoms resolve within 1-2 minutes. In addition to shaving, rubbing of a shirt collar while dressing or turning the head is another common cause of syncope due to CSH.
A patient has a significant drop in blood pressure after pressing on the carotid sinus, what is the likely underlying cause?
- Carotid sinus syncope (a subtype of situational syncope) is commonly seen in patients with atherosclerosis.
- This is managed with a pacemaker or alpha agonist like midodrine.
What causes orthostatic syncope?
Caused by:
- Hypovolemia.
- Medications (e.g., alpha or beta blockers).
- Autonomic failure (e.g., diabetes, Parkinson’s).
What are the medications culprits for orthostatic syncope?
Many that cause volume depletion.
What are the clinical features of orthostatic syncope?
- Lightheadedness.
- Dizziness upon standing.
- Syncope after prolonged standing.
How is orthostatic syncope treated?
- Fluids for hypovolemia.
- Fludrocortisone.
- Midodrine for neurogenic orthostatic hypotension.
What are examples of high-risk features in syncope requiring admission?
- Syncope during exercise
- Palpitations
- Abnormal ECG findings (e.g., VTach, bradycardia, prolonged QT, heart block, bifascicular block).
What causes cardiogenic syncope?
Bradyarrhythmias (e.g., sinus bradycardia, heart block, sick sinus syndrome) or ventricular arrhythmias (e.g., VTach).
How does onset help to distinguish a cardiogenic syncopal event, warranting a cardiac exam?
- Cardiogenic syncope often occurs suddenly without prodrome.
- Patients will regain consciousness quickly.
What are the initial clinically relevant diagnostic steps for cardiogenic syncope?
1) Auscultation of the heart
2) ECG
3) Telemetry
When a patient presents with syncope, what would prompt evaluation of the patient with a a transthoracic echocardiography?
Evaluation of the patient with a a transthoracic echocardiography should be performed in patients with syncope and clinical features such as exertional syncope or abnormal cardiac murmurs that are suggestive of structural heart disease.
What are the major structural heart diseases can cause cardiogenic syncope?
- Aortic stenosis (diastolic murmur, LVH on ECG).
- Mitral stenosis (diastolic murmur, p-mitrale on ECG).
- Hypertrophic cardiomyopathy (systolic murmur, LVH on ECG).
- Arrhythmogenic Right Ventricular Cardiomyopathy (no murmur, abnormal ECG).
- Anomalous Coronary Artery (no murmur, normal ECG).
The onset of cardiogenic syncope typically occurs at what point?
Usually during exertion.
What are the nonstructural causes of cardiogenic syncope?
- Brugada
- Congenital long QT
- WPW
How is cardiogenic syncope diagnosed when the index of suspicion is high for an underlying cardiogenic cause but there are equivocal findings on initial workup?
Cardiogenic syncope requires diagnosis with ECG or long term cardiac monitoring. A holter monitor is used when the diagnosis has not been specified. 24-hour Holter monitoring may be indicated to assess for cardiac syncope in patients who have clinical features (eg, syncope without autonomic prodrome) or ECG findings suggesting cardiac arrhythmia.
How is syncope from structural heart disease diagnosed?
- ECG.
- Transthoracic echocardiogram (TTE).
- Cardiac enzymes (Troponin or CKMB).
- Place the patient on telemetry monitoring if inpatient.
- Place the patient on a Holter monitor/Implantable loop recorder if discharging the patient.
If a patient had gradual loss of consciousness, what is the likely underlying cause of the syncopal event?
- Toxin or metabolic derangement (hypoglycemia).
- The workup includes glucose level checks, oxygen saturation, urine drug screen, and a CBC.
What are other potential causes of syncope?
- Heat syncope
- Pulmonary embolism
- Subarachnoid hemorrhage or TIA
If the patient had a sudden onset of loss of consciousness, followed by a gradual return to consciousness, what is most likely etiology for their syncopal event?
Neurogenic, the workup will require a head CT with EEG to evaluate for seizure.
