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
- 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:
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
- Accessory pathway (His PUrkinje system is bypassed)
- 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
- 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)
- SCDHeFT
- 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
- 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. |
|