Symptom To Diagnosis - Syncope Flashcards
Consciousness requires the following:
- Organized cortical electrical activity.
- Glucose.
- Oxygen.
- A functional delivery system to deliver oxygen and glucose.
The evaluation of ALL syncopal patients must include?
- Thorough history.
- Physical exam.
- ECG.
Neurocardiogenic (vasovagal) syncope - Textbook presentation:
Typically develops in young patients during prolonged standing at times precipitated by pain or anxiety (ie, phlebotomy).
–> Lightheadedness, nausea, and diaphoresis may precede syncope, which is BRIEF.
MCC of syncope:
Neurocardiogenic (vasovagal) –> 20-33%.
Pathophysiology of neurocardiogenic syncope:
- Low preload state due to venous pooling (from prolonged standing) or dehydration.
- Superimposed anxiety, pain or fears triggers a sympathetic surge.
- Sympathetic surge augments ventricular contraction.
- Vigorous contraction coupled with low preload results in LOW ESV, which triggers intracardiac mechanoreceptors.
- Mechanoreceptors trigger the vagal reflex.
- Vagal reflex triggers bradycardia, vasodilatation, or both, resulting in hypotension and syncope.
EBD of neurocardiogenic syncope - Provocative circumstances:
37% --> Prolonged standing. 42% --> Hot weather. 23% --> Lack of food. 21% --> Fear. 14% --> Acute pain.
EBD of neurocardiogenic syncope - Sensitive finding?
NO SINGLE FINDING is very sensitive (14-40%).
EBD of neurocardiogenic syncope - Certain findings are fairly specific and increase the likelihood of neurocardiogenic syncope when present:
LR+ 12 –> Feeling warm.
LR+ 9 –> Prolonged standing.
LR+ 8 –> Abdominal discomfort prior to syncope.
LR+ 7 –> Occurring during injection/cannulation.
EBD of neurocardiogenic syncope - Syncope DURING exercise should raise the suspicion of?
CARDIOGENIC SYNCOPE.
EBD of neurocardiogenic syncope - Lab and radiologic tests:
- Typical history, normal physical exam, ECG, + no evidence of heart disease or red flags –> NO FURTHER TESTING.
- Atypical history (without a clear precipitant) –> Echocardiogram + occasionally tilt-table testing.
HCM - Textbook presentation:
May be asymptomatic and discovered due to a family history of sudden cardiac death, during the evaluation of an asymptomatic systolic murmur, during pre-participation athlete screening, or when symptoms occur (syncope, HF, A-fib, cardiac arrest).
MCC of cardiovascular death among young athletes:
HCM.
HCM - Complications:
- HF.
- Angina.
- MR.
- A-fib.
- Stroke.
- Syncope.
- Sudden cardiac death.
Angina develops in …-…% of patients with HCM.
25-30%.
Syncope develops in …-…% of patients with HCM.
15-25%.
ANNUAL risk of sudden cardiac death among all patients with HCM:
0.6-1%.
Major risk factors for sudden cardiac death in HCM:
- Prior events –> Prior cardiac arrest + spontaneous sustained VT.
- High risk clinical factors:
a. Family history in 1st degree relative.
b. Unexplained syncope.
c. Massive LVH (>3cm).
d. Abnormal BP response to exercise.
e. Nonsustained VT on Holter monitoring.
Annual evaluation of patients with HCM:
- History and physical exam.
- Family history.
- Echocardiography.
- 48h-Holter.
- Exercise stress testing –> To assess BP response to exercise and evaluate ischemia.
EBD of HCM - Classic murmur of HCM - Increased and decreased when?
Increased –> By maneuvers that DECREASE chamber size (incr. obstruction) - Increases as the patient goes from a squatting to a standing position (sens 95%, spec 84%, LR+ 5.9, LR- 0.06).
Decreased –> Passive leg elevation –> Sens 85%, spec 91%, LR+ 9.4, LR-0.16.
EBD of HCM - ECG findings - Abnormal in?
92% (73% in asymptomatic patients without obstruction).
EBD of HCM - ECG abnormalities:
Repolarization abnormalities –> ST segment elevation, depression or T wave inversions) are found in 86% of patients although less common in asymptomatic, non obstructed patients (58%).
EBD of HCM - LVH present in …% of obstructed patients and …% of non obstructed.
81%.
48%.
EBD of HCM - ECG abnormalities may ?
Precede ECHOcardiographic abnormalities and may increase in frequency with age.
Cardiac syncope - Textbook presentation:
Elderly patients with known heart disease (ie HF, CAD) who experience sudden syncope, which may occur without warning.
Patients may have palpitations.
What is cardiac syncope?
Syncope 2o to a disorder arising within the heart.
- Arrhythmias (either tachyarrhythmias or bradyarrhythmias) –> MC.
- Occasionally –> Severe valvular heart disease (AS).
- Rare causes –> Aortic dissection, cardiac tamponade, atrial myxoma.
Cardiac syncope is associated with increased mortality. 1-yr?
1y mortality rate in patients with cardiac syncope is 18-33%, compared with 6% in patients with syncope of unknown cause.
Cardiac syncope - Among patients with DCM, sudden cardiac death (presumably arrhythmogenic) accounts for …% of mortality.
30%.
Why most SVTs do not produce syncope?
Because the AV node limits the ventricular response rate.
MC tachycardias associated with syncope:
- VT.
2. SVTs associated with an accessory pathway (ie WPW syndrome).
MC bradycardias associated with syncope:
34% of patients with heart disease have significant bradycardias.
- Sinus node dysfunction (sinus bradycardia, sinus pauses defined as >3 sec.
- AV heart block (2nd or 3rd degree).
- A-fib with slow ventricular response.
EBD of cardiac syncope - History - Specific, but not sensitive findings:
Syncope while supine –> LR+ 6.
Syncope during exertion –> LR+ 3.5.
Palpitations –> LR+ 5.8.
EBD of cardiac syncope - Certain ECG findings may suggest particular cardiac etiologies:
- ECG evidence of prior MI or a long QT interval increases the likelihood of VT.
- ECG findings of significant bradycardia, 2nd/3rd degree AV block –> Bradycardia.
- BBB suggests intermittent AV block.
- RV strain (S1Q3T3) or RBBB suggests PE.
- Ischemic changes suggest MI.
- Delta wave or short PR interval suggest an accessory pathway (WPW syndrome).
VT - Textbook presentation:
Patients with VT may be asymptomatic or have symptoms that range from palpitations to lightheadedness, near syncope, syncope, or sudden cardiac death.
VT is associated with CAD in …% of cases.
80%.
Other etiologies of VT:
- HF.
- HCM.
- Valvular heart disease.
- Drugs (antiarrhythmics, antipsychotic, TCA –> Prolong QT interval).
- Electrolyte disorder –> HYPOkalemia, HYPOcalcemia, HYPOmagnesemia.
- Congenital disorders.
Brugada syndrome as a cause of VT:
- UNUSUAL disorder 2o to mutation in the Na channel gene, which predisposes patients to polymorphic VT and sudden death.
- Suggestive baseline ECG abnormalities include a RBBB pattern with ST elevation in the right precordial leads.
ECG criteria for VT:
- > 3 CONSECUTIVE wide complex (QRS>0.12 sec) beats.
2. SVTs can also occasionally manifest wide QRS complexes.
ECG criteria that increase the likelihood that the wide complex tachycardia is VT include?
- Fusion beats.
- Capture beats.
- AV dissociation.
- QRS width >0.14sec.
Sustained VT is defined as VT lasting longer than …sec?
30seconds.
Evaluation of VT:
- Obtain a baseline ECG to look for evidence of ischemia, long QT syndrome.
- Stress testing (and coronary angiography in selected patients) is recommended for patients with exercise-induced syncope or chest pain or an intermediate or greater probability of CAD.
- Obtain an ECHO –> Evaluate LV function + rule out valvular heart disease.
- Electrophysiologic testing is recommended for selected patients.
Prognosis of VT:
- Potentially life-threatening arrhythmia.
- Predictors of mortality include:
a. Prior cardiac arrest.
b. LV dysfunction.
c. Post MI.
d. Inducible VT on EP studies.
Textbook presentation of bradycardia from SSS:
- Depends on duration and severity of the bradyarrhythmia.
- Sudden syncope when bradyarrhythmia severe + prolonged.
- Weakness, dyspnea on exertion, angina, TIAs, near syncope when bradycardia is less severe.
What is the MC indication for pacemaker placement?
Bradycardia from SSS.
What is the target group of bradycardia from SSS?
- Often seen in the elderly (mean age 68) due to fibrosis and degeneration of sinus node.
- Underlying CAD is common –> Contributes to the pathogenesis of SSS in some patients.
Medications that can depress sinus node function and aggravate SSS:
- Beta-blockers.
- Verapamil.
- Diltiazem.
- Digoxin.
- Clonidine.
- Methyldopa.
+ Other antiarrhythmics.
Bradycardia from SSS - Electrical manifestations include:
- Sinus bradycardia 2sec.
- Sinus arrest (with an escape junctional rhythm).
- Sinoatrial exit block (inability of the sinus impulse to exit the sinus node).
Concomitant AV conduction disturbances are present in over …% of patients with SSS.
50%.