Electric Boogaloo
The Brady Bunch
The only way out is through: AV Node
Manage this!
Phys and/or Drugs
Space Jam
100
Which phases of the cardiac AP correspond to what on the EKG?
Phase 0: Rapid upstroke = QRS deflection, driven by Na nd Ca currents
Phase 1 rapid upstroke, ST segment, Na channels dominate myocytes vs Ca currents dominate nodal tissue upstroke
Phase 2 ST Segment
Phase 3 T wave
Phase 4 segment b/w end of T wave and subsequent QRS deflection
100
What are 2 alternate names for ‘Intrinsic sinus node disease’?
Bonus 100: What are the 6 disease subtypes?
100
What are 2 alternate names for ‘Intrinsic sinus node disease’?
Bonus 100: What are the 6 disease subtypes?
SSS or sinus node dysfunction
-mechanisms are 2/2 problems w/ impulse formation or impulse conduction
Subtypes:
(1) sinus node exit block: failed impulse formation – failure of sinus node activity to propagate to the atrium
-Type I SA block: fixed delay out of the SA node
-Type II SA block: progressive delay and hten intermittent failure to propagate to atrium (Mobitz I) OR fixed delay w/ intermittent failure to conduct (Mobitz II)
-Wenckebach-progressive P interval shortening
(2) Tachy-Brady Syndrome: high HR w/ alternating symptomatic bradycardia
(3) Chronotropic incompetence: inability of heart to ↑ HR to meet demand
(4) Sinus node fibrosis
-old person – SA node ↑ fibrotic tissue & loss of pacemaker cells at the SA node
(5) SA node ischemia/infarct
-acute inferior or posterior MI
(6) Carotid sinus hypersensitivity / neurally mediated bradycardia
100
Give 3 infectious causes of AV blocks
Bonus 100 for microbe names AND Tx
(1) Lyme carditis Borrelia burgdorferi
-usually at level of AV node
Tx: doxy
Other Bacterial Bugs: Myoplasma pneumoniae, Corynebacterium diphtheria
(2) Chagas disease Trypanosoma cruzii
Tx: anti-protozoal Benznidazole or
nifurtimox
(3) toxoplasmosis gondii
Tx: Sulfadiazine +
pyrimethamine
NB: Bactrim is for toxo Prophylaxis for CD4<100
(4) Viral myocarditis
-coxsackie B, Parvo B19, adenovirus, COVID, HIV, HHV-6
100
This is recommended regardless of symptoms in patients with irreversible Mobitz II or third-degree AV block.
What is permanent pacing?
100
At baseline, this division of the autonomic nervous system predominates controlling the sinus node.
What is the parasympathetic nervous system?
100
Name Jupiter's Galilean moons (hint: there are 4)
Bonus 100: give total # of moons
Ganymede
Callisto
Io
Europa
Jupiter has a total of 95 moons making it the planet with the 2nd largest number of moons in our solar system. The 4 Largest moons of Jupiter are the Galilean moons first characterized by Galileo in 1610.
*Saturn has >140 moons
200
Mutations to K channels results in what?
Bonus 200: and what other ion channel mutation results in similar conduction abnormalities?
Inherited Long QT
Also have Na channelopathies
200
5 reversible causes of SSS or sinus node dysfunction
Reversible causes:
(1) Hypothyroidism
(2) OSA
(3) Hypothermia
(4) Lyme disease
(5) Rx
-β-blockers, clonidine, non-DHP CCB, neuro/psych Rx (lithium, donepezil, phenytoin, TCA, SSRI)
200
What is the normal AV node automaticity rate compared to the SA node?
Bonus 200: give exact rate values
AV node automaticity rate- 20-60 bpm
SA node 60-100 bpm
200
This is initial non-pharmacologic maneuver used in SVT to induce AV block.
What are vagal maneuvers?
200
These channel-blocking medications increase refractory period and help terminate reentrant arrhythmias.
What are K-channel blockers?
200
What elements/materials is Saturn composed of?
96% H2
3% He
trace % of ammonia, methane, water vapor, hydrogen sulfide
Known as the gas giant, has low density
*Jupiter is 90% H2, 10% He
300
What is the conduction velocity in the Pukinje fibers?
Bonus 300: compare to conduction velocity in the myocardial cells?
Purkinje 2-3 m/s
Myocardial cells 0.3-0.4 m/s
300
What artery does the SA node artery originate from in the majority of persons?
Bonus 300: name the artery the SA node originates from in the remainder of persons.
55-60% RCA
40-45% LCX
300
Give the general AND precise anatomic boundary landmarks of the AV node (Hint: boundaries are anterior, posterior, superior)
Bonus 300: what are the divisions of the AV junctional area AND what is the size of the AV node
AV Node Anatomic location:
Beneath RA endocardium – at apex of triangle of Koch
Anterior: septal tricuspid valve annulus
Posterior: CoronarySinus ostium
Superior: tendon of Todaro
Size Area: 3x5mm
Jxl Area divisions
-transition cell zone
-lower nodal bundle
-compact AV node
-penetrating part of the Bundle of His
Continues through annulus fibrosis and emerges as His bundle at ventricular septum
300
This syndrome is defined by >30 bpm increase in heart rate (or >120 bpm) within 10 minutes of standing without hypotension and first-line management.
What is postural orthostatic hypotension
Tx:
firstline: oral fluid (3L daily), sodium 8-12g po qd, exercise (incremental aerobic programs), countermeasures (leg crossing, muscle tensing), good sleep, address anxiety
(secondline: beta-blockers, vasopressor therapy/midodrine, fludrocortisone)
300
This intrinsic heart rate is observed after elimination of autonomic influence on the SA node (e.g. atropine).
What is 100-110 bpm?
300
The NASA Artemis II crew used what physics principle to travel around the moon and return home without any propulsion engine?
Free-return trajectory
The moon's gravity pulls the spacecraft and changes its velocity path into a curved trajectory with an escape velocity that allows it to slingshot back to earth without any propulsion engine
400
Name 4 arrhythmias where reentry is the mechanism
-Aflutter
-AV nodal reentry
-AV reciprocating tachycardia
-scar-based reentrant VT
400
Describe mechanisms of injury to the SA node artery OTHER than RCA infarct.
(HINT: iatrogenic)
Afib ablation → injury to SA node artery if traversing over a targeted ablation in the RA / LA ⇒ post-AF/Flutter ablation Cx are SND and SA node arrest
400
Give anatomic origins and termination landmarks of Right bundle branch VS Left Bundle branch
Bonus 400: what cardiac conduction tissue emerges from the RBB and LBB and which tissue layer is it located?
-RIGHT BUNDLE BRANCH
Origin- distal AV bundle
Termination: moderator band- a band that traverses the RV
LEFT BUNDLE BRANCH
Broad subendocardial sheet of tissue on the septal LV
Bonus: Purkinje fiber network endocardial surfaces of RV and LV
400
This reversible sleep-related condition should be suspected in patients with nocturnal sinus bradycardia and pauses and its treatment?
What is OSA?
Tx: weight loss, CPAP
400
These antiarrhythmics may paradoxically promote reentry by slowing down conduction and creating a larger excitable gap.
What are Na-channel blockers?
400
For how long to astronauts on the International Space station need to workout to maintain bone density/ mitigate bone and muscle loss?
2 hours per day at least of high-load resistance training and aerobic work
500
Describe the mechanism behind ablation for reentrant arrhythmias AND name an alternate method of ablation CURRENTLY used
Bonus 500 describe the steps of the procedure
A critical zone of SLOW conduction that sustains arrhythmia is targeted and ablated
Alternate: cryotherapy non-RF ablation (DC was previously used)
STEPS
(1) intracardiac mapping catheter measures electrical impedance and a magnetic field → real-time reconstruction of cardiac chambers identifies arrhythmogenic tissues as ablation targets
(2) Using alternatic electric current = RF energy → catheter tip heats local tissue → permanent injury Direct current energy → pulsation sof electric energy at pre-identified targets
500
List all indications for permanent pacemaker implantation for SA node dysfunction
Class I indications:
(1) Sx directly attributed to SND
(2) Symptomatic sinus brady from an essential Rx where there is no alternate Tx
(3) tachy-brady syndrome and Sx from brady part
(4) symptomatic Chronotropic incompetence
Class IIa:
(5) Sx possibly attributed to SND
*trial PO theophylline to ↑ HR and determine if permanent pacing would be beneficial
Class IIb:
(6) mildly Sx w/ HR<40
500
Give the 2 main Class I indications for permanent Pacemaker implantation for AV blocks
Class I
(1) Mobitz Type I w/o Sx but WITH neuromuscular disease associated w/ progressive conduction tissue disorder
(2) Complete AV block -acquired, advanced AV block, Mobitz Type II, evidence for infranodal block
500
This drug is given in doses of 6 mg, or 12 mg, and commonly used to treat AV-nodal-dependent SVT and three contraindications to its use.
What is adenosine and what are
second-third degree AV block,
sick sinus syndrome,
symptomatic bradycardia (unless pacemaker present),
known active bronchoconstriction,
preexcitation
500
This conductive tissue represents the final network distributing electrical impulses throughout the ventricles.
Spelling bee callback, spell it correctly.
Purkinje fibers
500
Which of Einstein's discoveries is the underlying physics behind radiographic imaging?
Photoelectric effect- described that light behaves as a particle (as well as the already known wave behavior).
*Light can be quantized- known as photon with discrete energy
ie an xray photon is absorbed by inner-shell electrons that get ejected in tissues with higher atomic numbers (ie bone) → differential absorption → less photons reach the detector than what was initially emitted → producing tissue imaging with varying contrast