Section 5: Rhythm Disorders Flashcards
Clinical presentation of atrial fibrillation
- Palpitations
- An irregular pulse
in a person with a history of hypertension, ischemia, or cardiomyopathy
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Location 2668). . Kindle Edition.
Diagnostic testing for A-fib
- EKG
- Telemetry monitoring (inpatient)
- Holter monitoring (outpatient)
Holter monitoring is a continuous, ambulatory cardiac rhythm monitoring for 24 hours or longer
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2669-2672). . Kindle Edition.
Atrial Fibrillation
For the CCS, apart from EKG what other daignostic tests should be done
- Echocardiography: Looking for clots, valve function, and left atrial size
- Thyroid function testing: T4 and TSH levels
- Electrolytes: Potassium, magnesium, and calcium levels
- Troponin or CK-MB levels: These may be appropriate to test in some acute-onset cases
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Location 2681). . Kindle Edition.
Rx of hemodynamically unstable patients with A-fib
How is hemodynamic instability defined in this context?
- Immediate synchronized electrical cardioversion
Unstable patients should be cardioverted with the first screen, without waiting for TEE or anticoagulation with heparin or warfarin
-
Hemodynamic instability is defined as:
- A systolic blood pressure < 90
- Congestive failure
- Confusion related to hemodynamic instability
- Chest pain.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2683-2686). . Kindle Edition.
Rx of hemodynamically stable patients with A-fib
- Stable patients should have their ventricular heart rate slowed if it is > 100– 110 per minute.
- Rate control medications are:
- beta blockers (metoprolol, esmolol)
- calcium channel blockers (diltiazem)
- digoxin
In the medications, such as metoprolol, diltiazem, or digoxin, combined with anticoagulation is equal or better than cardioversion with electricity or medications.
CHADS (CHF, hypertension, age > 75, diabetes, or stroke/ TIA) is a scoring system to indicate the need for warfarin or dabigatran. A score of 2 or more means warfarin, dabigatran, or rivaroxaban. A score of 0 or 1 means aspirin. CHADS C = CHF H = Hypertension A = Age > 75 D = Diabetes S = Stroke or TIA CHADS score of 0 – 1 needs aspirin. At 2 or more, use warfarin, dabigatran, or rivaroxaban.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2699-2707). . Kindle Edition.
What is the CHADS scoring system in A-fib management?
- CHADS (CHF, hypertension, age > 75, diabetes, or stroke/ TIA) is a scoring system to indicate the need for warfarin or dabigatran
- A score of 2 or more means warfarin, dabigatran, or rivaroxaban
- A score of 0 or 1 means aspirin. CHADS
- C = CHF
- H = Hypertension
- A = Age > 75
- D = Diabetes
- S = Stroke or TIA
CHADS score of 0 – 1 needs aspirin. At 2 or more, use warfarin, dabigatran, or rivaroxaban
Stroke/ TIA = 2 points
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2708-2709). . Kindle Edition.
What is the difference between A-fib and atrial flutter?
The rhythm is irregular in A-fib but regular in A-flutter. Management is the same.
In A-fib or A-flutter, which rate reducing medication is indicated in:
- Ischemic heart disease
- Migraines
- Graves disease
- Pheochromocytoma
Beta Blockers (Metoprolol)
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2714-2726). . Kindle Edition.
In A-fib or A-flutter, which rate reducing medication is indicated in:
- Asthma
- Migraine
Calcium Channel Blockers (Diltiazem)
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2714-2726). . Kindle Edition.
In A-fib or A-flutter, which rate reducing medication is indicated in:
- Borderline hypotension
- Digoxin
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2714-2726). . Kindle Edition
Multifocal Atrial Tachycardia (MAT)
This condition presents like an atrial arrhythmia in association with ———.
EKG features of MAT
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2728-2729). . Kindle Edition
- COPD/ emphysema
- EKG will show polymorphic P waves, revealing different atrial foci for the QRS complexes
- As the name implies, patients with MAT have tachycardia (heart rate > 100)
- MAT manifests as an irregular chaotic rhythm on EKG
- Do not use beta blockers
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2729-2733). . Kindle Edition.
Clinical presentation of Supraventricular Tachycardia (SVT)
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2734-2735). . Kindle Edition.
SVT presents with palpitations and tachycardia and occasionally syncope. It is not associated with ischemic heart disease. SVT has a regular rhythm with a ventricular rate of 160– 180.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2736-2737). . Kindle Edition.
Diagnostic tests for SVT
EKG
If the EKG does not show SVT, order Holter monitor or telemetry to increase the sensitivity of detection
On CCS, all cases of dysrhythmia should undergo transthoracic echocardiography (TTE) after the initial set of orders.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2738-2743). . Kindle Edition.
Rx for SVT
- Best initial management for unstable patients
- Best initial management for stable patients
- Best long-term management
- Synchronized cardioversion
-
Vagal maneuvers (carotid sinus massage, ice immersion of the face, Valsalva)
- Next best step in management if vagal maneuvers do not work: Intravenous adenosine (Note: This is the most frequently asked SVT question.)
- Radiofrequency catheter ablation
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2746-2748). . Kindle Edition.
Clinical presentation of Wolff-Parkinson-White Syndrome (WPW)
- WPW presents as SVT that can alternate with ventricular tachycardia (VT)
- The other main clue to the diagnosis is worsening of SVT after the use of calcium blockers or digoxin.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 2749-2752). . Kindle Edition.