Tachycardia Detection (SVT discrimination) 심재민 교수님.pdfSt. Jude Medical SVT-VT...
Transcript of Tachycardia Detection (SVT discrimination) 심재민 교수님.pdfSt. Jude Medical SVT-VT...
Tachycardia Detection (SVT discrimination)
Jaemin Shim, MD
Arrhythmia Center,
Korea University Anam Hospital, Seoul, Korea
Tachycardia Detection
Detection of a ventricular arrhythmia is based mainly on two rhythm characteristics ‒ Heart Rate (HR) or Cycle length (CL) ‒ Duration
A sustained ventricular HR >250 bpm or a CL
<250 ms is very specific for fast VT or VF
Tachycardia Detection: Heart Rate
Heart Rate
Sensing
Sinus Rhythm VT / SVT VT VF
50 bpm 100 150 200 250 300
Tachycardia Detection: Duration
Number of Interval Detection (NID), x out of y
Tachycardia Detection: Duration
If NID=12
If NID=18
Gunderson Gunderson et al PACE 2007
Cascade of Events Leading to ICD Shock
Circulation. 2013;128:659-672
Hardware Independent
Hardware dependent
Tachycardia Detection: Rate & Duration
Up to 3 programmable zones − Defined by heart rate (VF/FVT/VT) − Independently programmable rates, durations,
and therapies (ATP, shock)
VT zone: cumulative or consecutive counting VF zone: a percentage of intervals shorter than the rate cutoff, shorter detection duration
Tachycardia Detection: 1o Prevention
Primary prevention patients experience faster VTs with rates less likely to overlap SVT than secondary prevention
Programming of faster VT rate cutoffs with prolonged detection time is recommended (PREPARE, RELEVANT, MADIT-RIT trials)
Tachycardia Detection: 1o Prevention
Zone Rate Duration Therapy
Therapy zone 200 bpm 5-9 seconds ATP during charge, Max. Energy shock
Monitor-only zone 170-199 bpm 9-60 seconds None
ICD Programming for Primary Prevention
Tachycardia Detection: Heart Rate
Circulation. 2013;128:659-672
Primary Prevention
Secondary Prevention
VT
VT
SVT
SVT
Heart rate
Heart rate
Overlap Zone: Detection enhancement needed
SVT-VT discrimination
Single chamber discriminators − Onset − Stability − Morphology
Dual chamber discriminators
SVT-VT discrimination-Single Chamber
Onset
Stability
Morphology
Onset
Abrupt onset of VT
Slow warm up of sinus tachycardia
Onset
Onset misclassification ‒ The development of VT during sinus tachycardia ‒ The presence of ectopy immediately preceding
VT onset ‒ AF that begins abruptly
The onset algorithm makes its determination
only once, so that initial errors cannot be corrected.
Stability
Irregular RR intervals in AF
Stable RR intervals in VT
Stability
Variability in beat-to-beat RR intervals ‒ AF: variable, unstable intervals ‒ VT: regular/stable intervals
Applied during ongoing arrhythmia, so that a VT that begins with interval variability and stabilizes will be classified correctly
Stability misclassification ‒ Rapidly conducted AF (approximately >175 bpm) ‒ Regular SVTs such as atrial flutter ‒ Irregular VT (as may occur in the presence of
class 1C AAD) and polymorphic VT
Stability
Morphology
VT: morphology does not match template
SVT: morphology matches template
Morphology
The only non–interval-based single-chamber SVT-VT discriminator
Comparison of electrograms during tachycardia with a template acquired during normally conducted rhythm
The approach for aligning and comparing a tachycardia electrogram with a baseline template varies by manufacturer, but all have similar efficacy and failure modes
Most accurate of the single chamber algorithms (sensitivity: 92-99%, specificity: 90-97%)
Morphology
ICD leads and electrograms (EGMs)
Morphology
Not match Not match
• Parameter setting: 5/8, EGM > 60% match (St. Jude Medical) • In this case, 6 matches from 8 the algorithm votes for SVT (75%).
Morphology
JCE 2006;17:1310-19.
Sensitivity & specificity according to match threshold
Match Threshold (Medtronic Wavelet™)
Morphology
Misclassification ‒ SVT with rate-related aberrancy ‒ Errors in electrogram alignment ‒ Electrogram truncation (ie, signal clipping
caused by improper amplifier setting) ‒ Electrogram distortion caused by myopotentials ‒ Changes in morphology over time caused by
lead maturation or BBB ‒ Electrogram distortion in the minutes
immediately after shock delivery
Morphology
Morphology Error: Truncation
Not clipped
Clipped
Morphology
Morphology algorithms use either EGM only or a combination of EGM and a can to coil lead
Rhythm ID™ (Boston) discrimination algorithm based on an internal ECG electrode from can to RV and SVC coil.
SVT-VT discrimination-Dual Chamber
Significant addition is the comparison of atrial (A) and ventricular (V) frequency.
In case of V>A, VT therapy is initiated directly. For cases with V=A or V<A further
discrimination algorithms are used to differentiate between SVT and VT.
SVT-VT discrimination-Dual Chamber
RV tip to ring
Can to coil
Atrial EGM
SVT-VT discrimination-Dual Chamber
SVT-VT discrimination-Dual Chamber
Achilles’ heel of dual-chamber algorithms: Atrial sensing
Undersensing ‒ Low-amplitude electrograms (esp. during AF) ‒ Lead dislodgement ‒ Atrial blanking that occurs during and
immediately after ventricular sensed or paced events
Oversensing ‒ Large Far-field R-waves
SVT-VT discrimination-Dual Chamber
Far-field R-wave Oversensing in Dual Chamber ICD
SVT-VT discrimination-Dual Chamber
Medtronic (PR Logic)
Medtroni
c
SVT-VT discrimination-Dual Chamber
St. Jude Medical (Rate branch algorithm)
St. Jude Medical
SVT-VT discrimination-Dual Chamber
Boston Scientific (Rhythm ID)
SVT and VT Discrimination Criteria
Criteria ECG Single Dual CL or HR + + + Sudden onset + (Holter) + + Stability + + + Morphology + + + AV rate branch - - + QRS axis* + +* +* AVA interval - - + Sinus interval history ** - +** - Capture beats*** + - +*** RBBB & LBBB criteria + - -
*: Rhythm IDTM Boston; **: St.Jude Medical; ***: PR LogicTM Medtronic
Key Points
Prolonged or high rate detection 을 통해 SVT-VT discriminator 의 오류를 줄일 수 있다.
SVT/VT 가 overlap 되는 heart rate 영역에서 detection enhancement 가 필요하다.
Single chamber ICD의 SVT-VT discriminator 는 onset, stability, morphology가 있으며 이 중 morphology가 가장 유용하다.
Dual chamber discriminators 는 A lead의 function이 매우 중요하다.
고려대학교의료원 소개 2012. 00.
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Thank you for your attention.
Tachycardia Detection: Rate & Duration
Rate and duration triggering tachycardia detection is similar across all devices and is therefore hardware independent.
After tachycardia detection, algorithms may be applied to distinguish SVT from VT.
These algorithms are hardware dependent and differ markedly between single-chamber, dual chamber, and subcutaneous ICD.
Tachycardia Detection: 1o Prevention