One of the most important diagnostic tests in Cardiology to interpret is the EKG.

Here are my thoughts and notes. Will continue to this thread. Let me know what you think!

Thread #4: ECG Segments

#arjuncardiology #medtwitter #CardioTwitter #MedEd #IMG
General Principles:
- Positive deflection: wave of depolarization towards positive pole of that lead
- Negative deflection: wave of depolarization towards negative pole of that lead
- Biphasic deflection: wave of depolarization is perpendicular to a lead
Normal Sinus P-wave:
- Atrial depolarization that marks spontaneous depolarization of pacemakers cells in the right atrium
- Should be negative P-wave in aVR and upright in lead II
- Can communicate 'sinus rhythm with 1:1 AV conduction'
Normal QRS Complex:
- First phase: brief duration and spread of stimulus through interventricular septum (left side is stimulated first through branch of the left bundle of His); then depolarization spreads from LV to RV
- Second phase: Simultaneous stimulation of LV & RV
ST Segments:
- Represents early phase of ventricular repolarization (usually isoelectric); slight deviation (<1 mm may be seen normally)
- Can have short ST-segments and T-waves that appear to take off almost from J-point (variant of early repolarization)
Normal T-waves:
- Ventricular repolarization: return of stimulated muscle to the resting state (ST-segment, T-waves, and U-waves)
- Normally, should follow the direction of the main QRS deflection; should always be negative in aVR and positive in II and generally V4-V6
Stayed tuned for the next thread! Let me know what you think. Special thanks to these websites for these amazing graphics:

thoracickey.com/understanding-…
cvphysiology.com/Arrhythmias/A0…
litfl.com/j-point-ecg-li…
wikidoc.org/index.php/T_wa…

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More from @akhadilkarMD

Feb 6
One of the most important diagnostic tests in Cardiology to interpret is the EKG.

Here are my thoughts and notes. Will continue to this thread. Let me know what you think!

Thread #5: Axis Deviation

#arjuncardiology #medtwitter #CardioTwitter #MedEd #IMG
QRS Axis:
- General direction in the frontal plane towards which the QRS complex is predominantly pointed

- General rule: Mean QRS points mid-way b/w any 2 leads that show tall R-wave of equal height

- If depolarization is perpendicular to any lead, will see biphasic complex Image
Axis Deviation:
- For most people, the axis lies between -30 and + 100 degrees

- Left axis: < -30 degrees, lead II rS pattern (S-wave deeper than R-wave is tall)

- Right axis: > +100 degrees (R-wave in III > II) Image
Read 6 tweets
Feb 5
One of the most important diagnostic tests in Cardiology to interpret is the EKG.

Here are my thoughts and notes. Will continue to this thread. Let me know what you think!

Thread #3: ECG Leads

#arjuncardiology #medtwitter #CardioTwitter #MedEd #IMG
ECG Leads:
- Body act as a conductor of electricity; the recording electrodes in the arms, legs, and chest wall show the differences in voltage (potential) among electrodes
- Different views of the same event leads to different ECG patterns
ECG Limb Leads:
- 6 Limb leads (extremity leads) and 6 chest (precordial)
- 3 bipolar limb leads: I, II, III
- 3 augmented unipolar: aVR, aVL, and aVF
- 6 precordial leads: V1-V6
Read 7 tweets
Jan 26
One of the most important diagnostic tests in Cardiology to interpret is the EKG.

Here are my thoughts and notes. Will continue to this thread. Let me know what you think!

#arjuncardiology #medtwitter #CardioTwitter #MedEd #IMG
Conduction System:
- SA node (pacemaker cells) have specialized conduction tissue
- SA node is located in the RA near the opening of the SVC
- Stimulation occurs from right atrium to left atrium
- Simultaneous atrial contractions allows for blood filling into LV and RV
Conduction:
- AV Junction: Located at the base of the inter-atrial septum and extends into the inter-ventricular septum; the proximal portion is the AV node and distal portion is bundle of His
- Left & Right Bundle branches depolarize the myocardium via Purkinje fibers
Read 9 tweets
Jan 8
As a Cardiology fellow, we get a lot of consults for hypertensive urgency/emergency.

Part 4: Clinical Consequences of Hypertensive Urgency/Emergency

-thread 🧵-

#arjuncardiology #MedTwitter #Cardiotwitter #IMG #MedEd
1) Hypertensive Encephalopathy
- Cerebral edema is induced by markedly elevated blood pressures
- Dysregulation of auto-regulatory capabilities of the brain
- Characterized by headache, irritability, and altered mental status
- Treatment of choice: Nitroprusside/Labetalol
2) Reversible Posterior Leukoencephalopathy Syndrome (PRES)
- MRI may reveal white matter edema in the parito-occipital regions
Read 9 tweets
Jan 3
As a Cardiology fellow, we get a lot of consults for hypertensive urgency/emergency.

Part 3B: Therapy

-thread 🧵-

#arjuncardiology #MedTwitter #Cardiotwitter #IMG #MedEd
Fenoldopam:
- Used mainly by anesthesiologists to control BP intra-operatively
- Selective peripheral dopamine-1 receptor agonist approved for the management of severe HTN
- Arterial vasodilator w/ relatively short half-life
- Contraindicated w/ glaucoma b/c can raise ICP
Nicardipine:
- Dihydropyridine calcium channel blocker that inhibits vascular smooth muscle contraction
- Little to no activity on the AV or sinus node
- Does not raise ICP and reduces cerebral ischemia
- Contraindicated w/ advanced HF, acute MI, and renal failure
Read 8 tweets
Jan 3
As a Cardiology fellow, we get a lot of consults for hypertensive urgency/emergency.

Part 3A: Therapy

-thread 🧵-

#arjuncardiology #MedTwitter #Cardiotwitter #IMG #MedEd
Therapy:
- The presence of acute/rapidly progressive end-organ damage and not the absolute BP determines whether the situation is an emergency
- Goals should be based on mean arterial pressure (MAP) with close monitoring in ICU setting with arterial line
Therapy:
- In general, should reduce no more than 25% of MAP in the first 24 hours; after this time will be more gradual and allow auto-regulatory mechanisms to reset
- Exceptions: more aggressive BP reduction in aortic dissection, post-operative bleeding, and pulmonary edema
Read 11 tweets

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