Cardiology Flashcards
The most common arrhythmias include
Premature atrial contractions (PACs), Premature ventricular contractions (PVCs)
Four categories of arrhythmias?
- Bradyarrhythmias
- Supraventricular tachyarrhythmias
- Pre-excitation Syndromes
- Ventricular Tachyarrhythmias
Etiology of palpitations?
- Arrhythmias
- Psychiatric causes: anxiety, panic disorders
- Drugs/medications: alcohol, caffeine, over-the-counter agents (e.g., digitalis, phenothiazine, theophylline, beta agonists), street drugs (e.g., cocaine)
- Nonarrhythmic cardiac causes: Atrial or ventricular septal defect, Cardiomyopathy, Congenital heart disease, Congestive heart failure, Mitral valve prolapse, Pacemaker-mediated tachycardia, Pericarditis, Valvular disease (e.g., aortic insufficiency, stenosis)
- Extracardiac causes: Anemia, Electrolyte imbalance, Fever, Hyperthyroidism, Hypoglycemia, Hypovolemia, Pheochromocytoma, Pulmonary disease, Vasovagal syndrome
What are the drugs/medications that can cause palpitations?
Prescription drugs (eg, antiarrhythmics, digoxin, beta-agonists, theophylline, and rate-limiting drugs); over-the-counter drugs (eg, cold and sinus drugs, dietary supplements containing stimulants), including alternative medicines; and illicit drugs (eg, cocaine, methamphetamines). Caffeine (eg, coffee, tea, numerous soft drinks and energy drinks)
What should be asked on history for palpitations?
History of present illness should cover the frequency and duration of palpitations and provoking or exacerbating factors (eg, emotional distress, activity, change in position, intake of caffeine or other drugs). Important associated symptoms include syncope, light-headedness, tunnel vision, dyspnea, and chest pain.
Examples of supraventricular arrhythmias?
- Sinus Tachycardia
- Premature beats: Atrial Premature Beat, Junctional Premature Beat
- Atrial Flutter
- Multi-focal atrial tachycardia
- Atrial Fibrillation
- Atrioventricular nodal reentrant tachycardia
Examples of ventricular tachyarrhythmias?
- Ventricular Premature Beat
- Ventricular arrhythmia
- Torsades de Pointes
- Ventricular Fibrillation
Physical exam for palpitations?
- General exam + vitals
- JVP + thyroid
- Cardiac exam: rate and regularity of the rhythm as well as any murmurs
What to consider when seeing paroxysm of high BP?
Pheochromocytoma
Investigations + labs for palpitations?
- ECG
- Holter monitoring for 24 to 48 hours may be appropriate in patients with daily palpitations
- Loop recorder - Patients with very infrequent symptoms that clinicians suspect represent a serious arrhythmia
Labs:
- CBC +lytes, Mg and Ca
- Troponin (chest pain)
- TSH (hyperthyroidism)
Patients with newly diagnosed arrhythmia, findings suggesting cardiac dysfunction or findings suggesting structural heart disease require ____?
Echocardiography and sometimes cardiac MRI
What is sinus bradycardia and marked sinus bradycardia?
Sinus rhythm < 60 beats/min, but marked sinus bradycardia if <50
Causes of sinus bradycardia
- Increased vagal tone or vagal stimulation; drugs (e.g. β-blockers, calcium channel blockers); ischemia/ infarction
- Age-related degeneration of SA node = Sick Sinus Syndrome - Often associated with sudden tachycardias arising from chaotic atrial rhythms -‘tachy–brady syndrome’
What is 1st degree AV conduction blocks and who are they found in?
1° = every P wave conducts, but >200ms delay between start P & QRS. Usually benign, found in healthy individuals
What is 2nd degree AV conduction blocks?
Only a proportion of P waves conducted by AV node (2 types)
Examples of bradyarrhythmias?
- Sinus Bradycardia
- AV Conduction Blocks
Examples of pre-excitation syndromes?
- Wolff-Parkinson-White Syndrome (WPW)
- AV Re-Entrant Tachycardia
What is Mobitz I = ‘Wenckebach’?
P-waves conduct with progressive increase in PR interval. Consequence of impaired conduction within the AV node
Hallmark of Wenckebach
Grouped beating
Causes of Mobitz I = ‘Wenckebach’
Can be sign of high vagal/parasympathetic tone (e.g. athletes), can be consequence of myocardial infarct
Treatment of Mobitz I = ‘Wenckebach’
Anti-cholinergic drug
What is Mobitz II?
No preceding PR prolongation, sudden blocked P, often, fixed ratio of P’s conduct: 2:1, 3:1, 4:1 etc.
Is Mobitz II caused due to conduction disturbance proximal or distal to the AV node?
Usually due to conduction disturbance below/distal the AV node (i.e. bundle of His)
Treatment of Mobitz II?
Treatment is usually required with a pacemaker.
Causes of Mobitz II?
Can be sign of high vagal /parasympathetic tone (e.g. athletes), can be consequence of myocardial infarct
What is sinus tachycardia?
Sinus P waves >100bpm w/ normal QRS.
What is 3rd degree AV conduction blocks?
3 ° = NO P waves conducted - need escape rhythm @ or below AVN
Totally dissociated P-waves / QRS’s, therefore no relationship between atrium and ventricle
Etiology of sinus tachycardia?
Occurs in normal subjects with increased sympathetic tone (e.g. exercise, anxiety, pain, pregnancy), alcohol use, caffeinated beverages, drugs (e.g. β-adrenergic agonists, anticholinergic drugs)
Treatment of sinus tachycardia?
Treat underlying disease; consider B-blocker if symptomatic, calcium channel blocker if B-blockers contraindicated
What are the two supraventricular tachyarrhythmias premature beats?
- Atrial Premature Beat
- Junctional Premature Beat
How do you treat the supraventricular tachyarrhythmias premature beats?
Simple reassurance is appropriate, sometimes a beta-blocker
What are atrial premature beats?
PACs are observed on the surface electrocardiogram as a P wave that occurs relatively early in the cardiac cycle (ie, prematurely before the next sinus P wave should occur) and has a different morphology and axis from the sinus P wave (inverted or biphasic).
What are junctional premature beats?
Ectopic supraventricular beat that originates in the vicinity of the AV node. P wave is usually not seen or an inverted P wave is seen and may be before or closely follow the QRS complex (referred to as a retrograde, or “traveling backward” P wave)
What is atrial flutter?
Rapid, regular atrial depolarization from a macro re-entry circuit within the atrium (most commonly right atrium)
The atria depolarize at a rate of 250 to 350 beats/minute (typically 300 beats/minute). Because the atrioventricular (AV) node cannot usually conduct at this rate, typically half of the impulses get through (2:1 block), resulting in a regular ventricular rate of 150 beats/minute.
ECG of atrial flutter?
Saw-tooth flutter waves
What can you do in atrial flutter with 2:1 block to make the waves more easily seen?
In atrial flutter with 2:1 block, carotid sinus massage (first check for bruits), Valsalva maneuver, or adenosine may decrease AV conduction and allow flutter waves to be more easily seen
Treatment of acute atrial flutter
- If unstable (e.g. hypotension, CHF, angina): electrical cardioversion
- If stable:
o 1. rate control: B-blocker, diltiazem, verapamil, or digoxin
o 2. chemical cardioversion: sotalol, amiodarone, type I antiarrhythmics, or electrical cardioversion - Anticoagulation guidelines same as for patients with AFib
Treatment of long-term AFib
AFib includes antiarrhythmics and radiofrequency (RF) ablation (success rate dependent on site of origin of atrial flutter)
What is multi-focal atrial tachycardia?
Irregular rhythm caused by presence of 3 or more atrial foci (may mimic AFib)
Multi-focal atrial tachycardia occurs more commonly in which patients?
Occurs more commonly in patients with COPD and hypoxemia
Treatment of multi-focal atrial tachycardia?
Calcium channel blockers may be used (e.g. diltiazem, verapamil), B-blockers may be contraindicated because of severe pulmonary disease
What causes the initiation of atrial fibrillation?
Single circuit re-entry and/or ectopic foci, mostly arising from the pulmonary veins, act as aberrant generators producing atrial tachycardia (350-600 bpm), which leads to multiple re-entry circuity (microreentry). Impulses conduct irregularly across the atrial myocardium to give rise to fibrillation
What causes the maintenance of atrial fibrillation?
Maintenance: The tachycardia causes atrial structural and electrophysiological remodelling changes that further promote AFib; the longer the patient is in AFib the more difficult it is to convert back to sinus rhythm
What is atrial fibrillation?
In atrial fibrillation, the atria do not contract, and the atrioventricular (AV) conduction system is bombarded with many electrical stimuli, causing inconsistent impulse transmission and an irregularly irregular ventricular rate, which is usually in the tachycardia rate range.
ECG of atrial fibrillation?
No organized P waves due to rapid atrial activity (350-600bpm) causing a chaotic fibrillatory baseline irregularly irregular ventricular response (typically 100-180 bpm), narrow QRS (unless aberrancy or previous BBB)
Treatment of atrial fibrillation?
RACE
- Rate control: Beta-blockers, Verapamil, Diltiazem, or Digoxin. In patients with heart failure: digoxin, amiodarone
- Anticoagulation: NOAC
- Cardioversion (electrical)
If AFib <48 h, can usually cardiovert without anticoagulation
If AFib >48 h, anticoagulate for 3 wk prior and 4 wk after cardioversion due to risk of unstable intra-atrial thrombus
If patient unstable (hypotensive, active angina due to tachycardia, uncontrolled heart failure) should cardiovert immediately
- Etiology
What usually initiates atrioventricular nodal reentrant tachycardia?
Usually initiated by a supraventricular or ventricular premature beat
What is atrioventricular nodal reentrant tachycardia?
Re-entrant circuit using dual pathways (fast conducting β-fibres and slow conducting α-fibres) within or near the AV node; often found in the absence of structural heart disease
Pathophysiology of atrioventricular nodal reentrant tachycardia?
Premature atrial beat might find fast pathway refractory - conduct down slow pathway - fires ventricle - now fast pathway recovered - retrograde conduction back up - fires atrium retrograde (hidden P’s) - repetitive ‘short circuit’
Etiology of Wolff-Parkinson-White Syndrome (WPW)?
Congenital defect
ECG features of WPW
- PR interval <120 msec
- delta wave: slurred upstroke of the QRS (the leads with the delta wave vary with site of bypass)
- widening of the QRS complex due to premature activation
- secondary ST segment and T wave changes
- tachyarrhythmias may occur - most often AVRT and AFib
What is Wolff-Parkinson-White Syndrome (WPW)?
- An accessory conduction tract (Bundle of Kent; can be in right or left atrium) abnormally allows early electrical activation of part of one ventricle
- Impulses travel at a greater conduction velocity across the Bundle of Kent thereby effectively ‘bypassing’ AV node
What initiates AV Re-Entrant Tachycardia?
Initiated by a premature atrial or ventricular complex
What is Orthodromic AVRT
Stimulus from a premature complex travels up the bypass tract (V to A) and down the AV node (A to V) with narrow QRS complex (no delta wave because stimulus travels through normal conduction system)
What is AV Re-Entrant Tachycardia?
Re-entrant loop via an accessory pathway
Treatment of AV Re-Entrant Tachycardia?
- Acute: similar to AVNRT except avoid long-acting AV nodal blockers (e.g. digoxin and verapamil)
- Long-term: for recurrent arrhythmias ablation of the bypass tract is recommended
What is Antidromic AVRT?
More rarely the stimulus goes up the AV node (V to A) and down the bypass tract (A to V); wide and abnormal QRS as ventricular activation is only via the bypass tract
Is antidromic AVRT or orthodromic AVRT more commonly associated with WPW syndrome?
Orthodromic AVRT comprises 95% of the reentrant tachycardias associated with WPW syndrome
What is ventricular premature beat?
Impulse travels from its ectopic site through the ventricles via slow cell-to-cell connections rather than through the normal rapidly conducting His– Purkinje system.
ECG of ventricular premature beat?
QRS width >120msec, no preceding P wave, bizarre QRS morphology
What is ventricular arrhythmia?
3 or more consecutive ectopic ventricular complexes. Often >160ms
What is ventricular flutter?
Ventricular flutter: if rate >200 bpm and complexes resemble a sinusoidal pattern
What is “sustained VT”?
“sustained VT” if it lasts longer than 30s
Favour Dx of VT
Left axis or right axis deviation, nonspecific intraventricular block pattern, monophasic or biphasic QRS in V1 with RBBB, QRS concordance in V1-V6
What is monomorphic VT?
Identical complexes with uniform morphology. Typically result from intraventricular re-entry circuit, may be idiopathic without any structural heart disease
Is monomorphic VT or polymorphic VT more common?
Monomorphic VT more common than polymorphic VT
What is polymorphic VT?
Complexes with constantly changing morphology, amplitude, and polarity
Treatment of ventricular arrhythmia?
- Sustained VT (>30 s) is an emergency requiring immediate treatment
- Hemodynamic compromise: electrical cardioversion
- No hemodynamic compromise: electrical cardioversion, amiodarone, type Ia agents (procainamide, quinidine)
Is monomorphic VT or polymorphic VT more frequently associated with hemodynamic instability
Polymorhpic VT is more frequently associated with hemodynamic instability due to faster rates (typically 200-250 bpm) vs. monomorphic VT
Treatment of Torsades de Pointes?
Treatment: IV magnesium, temporary pacing, isoproterenol and correcting the underlying cause of prolonged QT, electrical cardioversion if hemodynamic compromise
Sometimes an implanted defibrillator
Who is more predisposed to Torsades de Pointes?
Predisposition in patients with prolonged QT intervals
Causes of prolonged QT intervals
- Congenital long QT syndromes
- Drugs: e.g. class IA (quinidine), class III (sotalol), phenothiazines (TCAs), erythromycin, quinolones, antihistamines
- Electrolyte disturbances: hypokalemia, hypomagnesemia
- Nutritional deficiencies causing above electrolyte abnormalities
What is Torsades de Pointes?
A variant of polymorphic VT that occurs in patients with baseline QT prolongation – “twisting of the points”
ECG of ventricular fibrillation?
Ventricles look like a ‘bag of worms’
What is ventricular fibrillation?
Chaotic, random, colliding wave fronts of electrical activity CARDIAC ARREST
Treatment of ventricular fibrillation?
Only treatment = immediate electrical DEFIBRILLATION
Etiology for generalized edema?
- Increased capillary hydrostatic pressure
- Increased plasma volume due to renal sodium retention
• Heart failure
• Reduced systemic vascular resistance (e.g., cirrhosis)
• Primary renal sodium retention (e.g., renal disease, drugs)
• Pregnancy
• Premenstrual edema
- Decreased arteriolar resistance (e.g., calcium channel blockers, idiopathic) - Decreased oncotic pressure (hypoalbuminemia)
- Protein loss (e.g., nephrotic syndrome)
- Reduced albumin synthesis (e.g., liver disease/cirrhosis, malnutrition) - Increased capillary permeability (e.g., burns, inflammation)
- Increased interstitial oncotic pressure (e.g., myxedema)
Etiology for localized edema?
- Venous insufficiency (including postphlebitic syndrome)
- Deep venous thrombosis (DVT)
- Trauma
- Lymphedema (e.g., malignancy, primary)
- Infection (cellulitis/soft tissue/bone)
- Inflammation (e.g., ruptured Baker cyst, chronic dermatitis)
What should be asked on history for generalized/localized edema?
- SOB (PE, HF), sx of hypothyroidism (slow mental and physical activity, weakness, or fatigue
- Meds
- PMHx: HTN, diabetes, thyroid disease, COPD, sleep apnea
- Social: alcohol use, liver disease
Signs and symptoms of generalized/localized edema?
- Unilateral or bilateral
- Dependency of edema
- Timing of edema
Bilateral (or, generalized edema) suggests ______
Systemic
Unilateral edema suggests _____ or _____ or _____
Local compression
Obstruction of vein
Lymphatic drainage
Edema that improves with limb elevation and worsens with dependency typically occurs with _____ and volume expansion
Venous insufficiency
Edema that does not worsen with dependency is associated with _____ found in conditions such as malabsorption, liver failure, and nephrotic syndrome
Decreased plasma oncotic pressure
Acute onset of edema (< 72 hours) in a limb with or without pain and erythema may suggest?
Deep venous thrombosis, cellulitis, ruptured popliteal cyst, acute compartment syndrome due to trauma, or use of a recent new medication (especially calcium channel blockers)
Peripheral edema occurs frequently in _____, often involves lower extremities, and typically begins during second trimester and is resolved during third trimester
Normal pregnancy
Chronic accumulation of generalized edema (> 72 hours) suggests onset or worsening of chronic systemic conditions such as?
CHF, renal disease, or hepatic disease
Physical exam findings for generalized/localized edema?
- Vitals: fever (cellulitis, hypotension (HF or cirrhosis, hypertension (renal disease), JVP (elevated = heart failure, constrictive pericarditis)
- Skin: Warmth (cellulitis), Signs of chronic venous insufficiency, Signs of myxedema
- HEENT: Nonpitting periorbital edema - myxedema (due to hypothyroidism) or nephrotic syndrome
- Cardiac: Valvular heart disease or S3 gallop indicative of low ejection fraction
- Lungs: SOB - pulmonary edema and/or heart failure
- Abdomen: Signs of liver failure
- Extremities: Pitting edema - found in dependent areas such as lower extremities (or sacrum if at bed rest). Nonpitting edema – lymphedema, myxedema, lipedema
Signs of chronic venous insufficiency
Brawny, reddish coloration of skin, especially at medial ankle/calf. Progression to lipodermatosclerosis, characterized by fibrosis, hemosiderin deposition, and/or ulceration or erosions (especially over malleolus)
Signs of myxedema
Due to hypothyroidism - generalized dry, thick skin, yellow to orange skin discoloration over knees, elbows, palms, and soles
Signs of liver failure
Enlarged or shrunken liver, which may suggest scarring. Other signs suggestive of cirrhosis such as jaundice, spider angiomata, and caput medusae. Presence of ascites may suggest advanced liver disease, right heart failure, or constrictive pericarditis
Investigations for generalized edema to rule out cardiac, liver and renal causes?
- Blood chemistry panel including serum creatinine and liver function tests to assess kidney and liver function
- Serum albumin to assess for nephrotic syndrome, liver disease, protein-losing enteropathy and malnutrition states
- Plasma B-type natriuretic peptide (BNP)
- Urinalysis to look for albuminuria and other signs of renal disease
- Chest x-ray to assess for heart failure and chronic obstructive pulmonary disease (COPD)
- Electrocardiogram to detect ischemic heart disease or pericardial disease
- Thyroid-stimulating hormone levels to rule out hypothyroidism
Investigations for acute localized edema?
D-dimer, duplex US
Investigations for generalized edema to rule out chronic venous insufficiency?
Chronic venous insufficiency: duplex ultrasonography, ankle-brachial index to evaluate for arterial insufficiency
Investigations for chronic localized edema?
- If patient has history of cancer, pelvic surgery, or trauma, perform pelvic magnetic resonance venography to detect tumor or obstruction
- If clinical exam suggests lymphedema, confirm with lymphoscintigraphy and/or T1-weighted magnetic resonance lymphangiography