Cards

Day 2: Electrophysiology
10-20 % of Atrial Tachycardia can respond to Adenosine.

Physiological Classification
  • Focal
  • Macro-reenterant
    • Need to ablate the critical isthmus 
  • Decrimental conduction property of fast conducting fibers of the av node 
  • AVNRT
    • Typical:
      • Down the slow AV tract
      • P wave closer to QRS means it is typical AVNRT 
    • Atypical: Down the fast AV tract 
      • P wave further out from QRS 
  • Accessary Pathway
    • Are non-decremental
    • 5 % are multiple
    • Shorter refractory period
    • Persistent or Intermittent 
    • Closer the pathway, more is the ventricular pre excitation 
    • Concealed Pathway
      • More often is due to retrograde conduction from these pathway. Not top to down. 
  • PR and RP relationship
    • Short RP Tachycardia 
    • Long RP Tachycardia
      • Atrial tachycardia
      • Atypical AVNRT
      • ORtw with a slow decremental pathway (PJRT)
  • Focal tachycardia coming close to Sinus Node can give a false impression of Sinus Tachycardia 
  • MAT
    • Pulmonary Disease
    • Dig toxicity 
  • Wide complex SVT
    • Pre-existing BBB
    • SVT with Right or Left bundle aberrancy
    • Antidromic Tachycardia
    • Atrial Fibrillation with pre excitation
      • Do not give adenosine. 
      • Recognising this perhaps most important.  
  • VT can give a impression of BBB
    • RBBB : even if typical do not close the diagnosis just yet 
  • Coumel's Tachycardia
    • Orthodeomic Tachyacarid with LBBB 
      • BBB now starts to conduct, causing shorter QRS on tachycardia 
Atrial Fibrillation
  • Even after ablation, anti-coagulation should continue based on CHADS VaSc score. 
  • Warfarin reduces the risk of stroke by 64 %
  • Role of Thrombin
    • Causes Fibrin formation, 
    • Also, causes platelet activation and stabilizes the clot 
  • NOAC vs warfarin in A fib
    • No data of NOAC for Cr Cl < 30
    • NOAC not indicated for ESRD 
    • If INR is at goal at >70% of the time, warfarin is effective in reducing the risk of stroke . In all the studies of NOAC vs Warfarin for A Fib, INR was at goal in 50-68%. Non-had >70% . 
  • Non-valvular AF (definition) 
    • Rheumatic Mitral Stensosi
    • Mehcniacl heart valve
    • Bioprosthetic heart valve
    • Mitral Valve Repair 
  • INR
    • On warfarin, unable to reach the therapeutic INR is not same as non-compliant.
      • Genetic factors??
      • Also, patient on NOAC are not necessarily compliant 
  • Watchman is reasonable in selected patients
    • Not all patients with A fib are from atrial appendages. .... % are. 
    • Appropriate rationale is used
      • Eg. Patient has had recurrent fall that is getting worse. You can put watchman, and continue anti-coag for 45 days after implant until watchman is endothelised, then we can stop anti-coag. 
  • Caution in diagnosis of Atrial flutter vs a fib
    • Flutter wave is of same morphology
  • Caution in a fib vs MAT
  • Atrial Tach vs A Flutter in EKG
    • Rate > 200
    • Look for isoelectric line (atrial flutter has no isolectric line that is representation of atrial depolarization)
      • 2 exceptin
        • No prior history of cardiac surgery or ablation. If yes, it is atrial flutter. 
  • Atrial tissue does not rely on coronary vasculature for oxygen. Hence, Stress test is done only in a symptomatic patient. 
  • New onset A fib
    • Look for cause: 
      • PE, OSA, HTN, Structural heart disease, hypothyroidism 
  • Patient with A fib and HCM are at high risk of stroke, and should be anti-coagualted even though low CHADS VaSC of 0. HCM is treated like non-valvular a fib. 
  • GI bleeding due to embolic ischemia is common. Such patients need to be on oral anticoagulation. 
  • CHAD VaSC of 1 in a women due to gender is to be disregarded. It counts if other risk factor is present.
  • A fib duration of > 6 min or > 6 hr of atrial fib causes increased risk of stroke. Any duration a fib in a high risk chadvasc patient should be treated , but no data to suggest if duration < 6 min
  • When to ablate by cardioversion for new onset A Fib
Premature Ventricular Contractions
  • Significance:
    • Symptoms (SOB, Frequent cause of palpitation) 
    • Cardiomyopathy
      • Not all patient with PVC have cardiomyopathy
      • Burden above 10-25 % if often implicated 
      • Chicen or Egg?
    • Mortality
      • increased Mortality after MI
      • increased mortality with LVH
      • EF < 35 %
        • Frequency did not provide prognostic information in this patient group 
      • Short coupled PVCs
        • < 300 ms. Risk of increased V. Tach
        • R on T phenomenon
        • Suggest short QT
  • Family history is relevant for appropriate risk stratification
  • Exercise test in select few patients
    • Esp if ischemia is a concern 
    • If provoked by exercise 
  • Location of PVC
    • mostly outflow tract
      • RVOT foci
      • LVOT foci
        • Difficult to identify the foci
        • Outfolow tracts are inter winded to each other 
    • valve annulus
      • MV annulus (5 %)
    • others...
  • Mechanism of PVC
    • cAMP mediated Ca dependent delayed activation 
    • few have macrorenterant mechanism 
  • Treatment
    • Usually dictated by symptoms
    • No specific therapy
    • Meds: 
      • BB (if they can tolerate)
        • 10-15 % patient will have 90% reduction
      • CCB (less data)
        • Fasicualr PVC, Short coupled
      • Anti-arrythmic drugs
        • may be better, but may not have survival advantage 
    • Surgery:
      • Ablation
Wide-complex Tachycardia
  • Definition:
    • Rate > 100 bpm
    • QRS > 120 msec
  • Etiology : 4 categories 
    • V Tach
    • SVT with abnormal ventricular activation
      • Aberrant conduction via normal conduction pathway (in BB, or distal purkinji system)
        • BBB, IVCD (intraventricular conduction delay), rate-related aberrancy 
      • pre-excitation of ventricle 
    • Ventricular paced rhythm
    • Recording defect or artifact 
  • How to differentiate
      • Rate and Hemodynamic stability ARE NOT factors
    • QRS: NorthWest axis : VT
    • Every thing is positive in lead in QRS: VT 
    • Capture beats and Fusion Beats : signifies AV dissociation. VT 
    • Morphology Criteria
      • RBB Morphology
        • True RB or not
          • Favors RBB:

          • Favors VT:
            • First R bigger than r' (V1)
            • >140 ms
      • LBB Morphology
        • True LB or not
          • Favors LLB
          • Favors VT
            • Any Q or QS wave in V6

    • Brugada Algorithm for the differentiation
      • Precordial leads: 
        • RS in same side in all precordial leads
        • R to S interval > 100 ms
        • AV dissociation
        • Morphology criteria for VT 
          • This has good sensitivity and specificity 
Pathogenesis of Brugada vs LQT3 (that occurs with sleep)
  • Loss of function of SC5N (Sodium Channel): Brugada
  • Gain of function of SCN5: LQT3
Polymorphic VT
  • Long QT
  • Catecholamine induced 
  • Short Coupled Polymorphic VT (rare) 
    • Typically, Verapamil is not given for VT, but in this case it is Verapamil sensitive VT 
Use Calliper 
Questions where 40 % of attendant were getting it wrong 

SCD
  • Primary Prevention of SCD (in high risk patient)
    • Class Ia recommendation are based on the clinical trial inclusion criteria
    • Ischemic Cardiomyopathy (Nice slide is there)
      • MADIT (1996)
      • MUSTT (1999)
        • CAD
        • EF <40
        • Induscible Sustained VT in a patient with Nonsustained VT e
      • MADIT2 (2002)
        • Prior MI
        • EF <30
      • SCDHeFT
        • NYHA II-III, EF < 35
    • Non-ischemic Cardiomyopathy
      • SCDHeFT (had both patient population)
      • Companion
  • Secondary Prevention of SCD
    • AVID (1997)
    • CASH (2000)
    • CIDS (2000)
  • Slide on incidence of SCD population and patient studied by primary prevention RCT 
  • Usually STEMI is not seen in normal ECHO 
  • Polymorphic VT are mostly ischemic 
  • Paper
    • 2015 Heart and Rhythm management of postural tachycardia syndrome .... 2015 
Pacemaker 
  • Indications
    • SN dysfunction: HR < 40
    • AV Block
      • Symptomatic any type
      • Aymptomatic 
        • 3rd AV Block, Infra-husian 2nd (EP study parameters), any Mobitz II
        • 2nd AV block with rates < 40 bpm or pauses > 3s
    • Bifascicular AV block
      • Alternating BBB, syncope of unknown cause
    • Neuromuscular Diseases
    • Post-MI
      • Anterior ? vs Inferior
    • Neurocardiogenic Disorders
    • Carotid Sinus Hypersensitivity
    • ? Vasovagal syncope 
ICD
  • Subcutaneous
    • Not used if patient has a current or future indication for pacing 
    • Transvenous is better for monomorphic VT 
  • Transvenous 
    • RV coil (anode +)
    • SVC coil (cathode -)
      • Note: generator is also cathode -
  • ICDs handle VT and VF differently 
  • Question:
    • How does device differentiate between SVT and VT?
      • Answer: By looking into following features 
        • Onset
        • Stability
        • Morphology
        • V-A Relationship
    • Cardiac Sarcoid
    • HC
  • Note: Remote monitoring actually helps in mortality benefit
    • Likely mechanism:
      • Early detection of A fib
      • Early detection of mis-firing or appropriate firing, and bringing these patients  identifying the cause and timely optimization of medical therapy may be the reason for improve survival advantage
        • Note: Shocks themselves are associated with poor longterm outcome. So, we have to avoid any unnecessary  shocks. 
Pacemaker and ICD sense differently 
  • Understanding how each sense the abnormality is the key in understanding pacemaker or ICD 
Question:
ASA for patient with PAD, CAD by CT but no prior CHF, MI, Stroke. Is this Primary Prevention or Secondary Prevention?
There are now subspecialty guidelines 

Grafts 
  • Mechanical
  • Bioprosthetic
  • Homograft
    • Calcifies
    • Hard to remove
    • Hence, only used in people who have infection
Cardiac MRI 
  • 25 % of TTE have poor acoustic window
  • Gold standard for LV / RV flow and volume 
    • ECHO assessment of RV is very subjective. MRI gives more objective assessment. 
  • A fib or frequent PVC result in sub-optimal gating 
  • Role of MRI is more prominent in asymptomatic patients 
  • MR: 
    • TTE, if not good
      • Either TEE or CMR are class I indication
  • AR:
    • Class I for suboptimal echo LV EF, Vol, and AR severity 
Role of Mechanical / Pharmacological Thrombectomy
Ongoing Trial
Enrollment has stopped. 
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