Cardiac devices Flashcards
What are class 1 indications for pacemaker insertion? (6)
- Complete AV block (with or without symptoms)
- Advanced 2nd degree AV block (block of 2 consecutive P-waves
- Especially the ones with high-risk features: HF, pause ≥3 seconds, ventricular escape rhythm <40
- Symptomatic 2nd degree AV block (Morbitz type I and II)
- Asymptomatic Morbitz II with widened QRS or chronic bifascicular block
- Exercise-induced 2nd or 3rd degree AV block
- Sinus node dysfunction with symptomatic bradycardia (e.g. sinus bradycardia)
What are class II indications for pacemaker insertion? (3)
Asymptomatic 2nd degree AV block (Morbitz type II) with narrow QRS (if wide, class 1)
1st degree AV block with haemodynamic compromise due to effective dissociation secondary to very long PR interval
Bi/Trifascicular block with syncope where it is attributed to transient complete HB
What are the 3 indications for implantable cardioverter-defibrillator (secondary prevention)? (2)
Patients with prior episodes of…
- Resuscitated VT/VF
- Spontaneous sustained VT
- In the presence of heart disease (cardiomyopathies - valvular, ischaemic, hypertrophic, dilated or infiltrative – i.e. structural disease) OR
- Where a completely reversible cause cannot be identified (e.g. idiopathic VT/VF, congenital long QT)
- Not VT/VF occurring within 48 hours following MI
Indications for ICDs in the setting of primary prevention? (3)
Basically patients with high-risk of SCD due to VT/VF despite optimal medical management (ACE and beta-blockers for ≥3 months), including patients with…
- Prior MI (but at least ≥40 days ago) + LVEF <30%
- Cardiomyopathy + NYHA 2-3 + LVEF <35%
- High-risk congenital disorders: HOCM, ARVC, Long-QT, Brugada and chanelopathies
What is the minimum length of expected survival / functional status for someone being considered for ICD insertion?
1 year
Acceptable functional status
This is even if they otherwise meet the criteria
What are the contraindications to ICD insertion? (5)
- Expected survival <1 year with poor functional status
- Completely reversible causes (e.g. electrolyte imbalance, drugs)
- Infection (but can bridged with wearable cardioverter/defib - WCDs)
- Severe psychiatric illnesses (that could be aggravated by device - rare)
- Where other therapies should be considered first, where the risk of SCD is normalized after a successful procedure (Catheter ablation, Surgical intervention)
5 things that determine indication for CRT?
LVEF
QRS duration
QRS pattern
NYHA
Need for ventricular pacing
What are the class 1 indications for CRT?
LVEF ≤ 35%
Wide LBBB ≥ 150ms (i.e. ≥ 4 small squares)
NYHA class II to IV symptoms
Decision regarding CRT vs ICD based on age/cormorbidities
Other indications are there, but a lot less robust evidence – such as (basically meets only 1 of the above criterias)
QRS >150 with non-LBBB
QRS 120-149 with NYHA III-IV + recurrent HF
LVEF 35-50% but long QRS + III-IV symptoms
What are the names of (2) trials that showed that patients with RBBB, QRS <120 ms are much less likely to benefit, and often do worse even if LVEF <35%?
ReThinkQ
LESSER-EARTH
Would you consider CRT in patient with AF who otherwiese meet the criteria?
It is much more difficult to enforce biventricular pacing → at this stage, they do not fulfill the criteria
What are the risks/disavantages associated with CRT that must prompt you to consider before putting it in? (6)
- CRT implantation is longer + entails more procedural risk
- Increased risk of infection c/w ICD or PPM insertion
- LV leads leads have higher risk of dislodgment or pacing phrenic nerve compared with traditional RV leads
- Shorter battery longevity
- Not all will have the same benefits despite same indications (non-responders) – i.e. in preventing hospital admissions or improving LVEF
- “Negative responders” – actually becomes worse
What are the factors (radiographic/ECG/symptom features) associated with less benefit from CRT? (4)
Greater scar burden – by MIBI or Cardiac MRI
Non-LBBB
QRS <150
Milder symptoms
What are the implications of having severe COPD or CRF in considering CRT?
If symptoms predominantly derived by COPD – less benefit
Severe CKD – less benefit and higher risk of device-related infection
Especially if the patient is on HD - ↑ risk of bacteremia, endovascular lead infection, hematoma, compromisation of vascular access, limited access to placement
What are the contraindications for CRT? (3)
Similar to ICD such as active bloodstream infection
Frailty or comorbidities that limits expected survival with good functional capacity <1 year
Anaesthetic concerns
Pacemaker modes - VVI or VVI (R)?
What does it mean?
Main indication (1)
Main problem (1)
VVI
- ventricular pacing and sensing
- if no electrical impulse sensed then pacemaker will pace @ a pre-programmed rate
- if electrical impulse sensed then pacing inhibited
Main indication = AF with slow ventricular response. Advantage = prevents bradycardia.
Main problem = ventricular pacing cannot maintain AV synchrony, which can lead to pacemaker syndrome.
What is are the option for patients who are at risk of SCD but does not meet criteria for implanted ICD (e.g. due to active infection)? (2)
- Wearable Cardioverter-Defibrillator (WCD)
- Subcutaneous ICD (S-ICD)
