CRT: Non responders and hyperresponders - ANSWER-- 30% of CRT pts are "nonresponders"
- In a subset of patients CRT therapy resulted in normalization of LV function. This finding is observed exclusively in the subgroup of patients with nonischemic DCM and suggests that LBBB may be the causal facto...
CRT: Non responders and hyperresponders - ANSWER-- 30% of CRT pts are
"nonresponders"
- In a subset of patients CRT therapy resulted in normalization of LV function. This
finding is observed exclusively in the subgroup of patients with nonischemic DCM and
suggests that LBBB may be the causal factor DCM in this subgroup of pts.
Where are LV leads implanted - ANSWER-Lateral or posterolateral wall
CRT non-responder likely result of - ANSWER-- pt selection. does not have mechanical
dyssynchrony
- lead placement. not mid lateral or may have had lateral wall infarct
- suboptimal programming: AV or VV timing
Brugada and SIDS - ANSWER-- Genetically determined SCN5A
- Loss of function mutations in SCN5A in 20% of brugada syndome pts
-SCN5A accounts for about half of channelopathic SIDS cases
-RBBB, ST elevation precordial leads
- Untreated- Death
-May be treated by ICD
- EKG is definite marker in symptomatic and asymptomatic pts
Brugada syndrome - ANSWER-- Progressed from being a rare disease to one that is
second only to automobile accidents
- Electrocardiographically characterized by a distinct ST-segment elevation in the right
precordial leads, the syndrome is associated with a high risk for SCD in young and
otherwise healthy adults, and less frequently in infants and children
-patients with spontaneously appearing Brugada ECG have a high risk for sudden
arrhythmic death secondary to VT/VF. The ECG manifestations of Brugada syndrome
are often dynamic or concealed.
Silicone Rubber - ANSWER-- proven history
- longevity > 15 years
- very flexible
- repairable
- easy to process
-can tear
- reasonable tough
- thicker walls
- can abrade
- high coefficient of friction
- larger diameter
, Polyurethane (80A) - ANSWER-- adverse history
- longevity <7 years
- flexible
- not repairable
- very process dependent
- somewhat tear resistant
- tougher
-thinner walls
-abrasion resistant
- low coefficient of friction
- smaller diameter
Polyurethane (55D) - ANSWER-- most currently used
- proven history
- > 12 years
- less flexible
- not repairable
- easy to process
-very tear resistant
-very tough
- thinner walls than 80A
- abrasion resistant
-May be more prone to RV perforation
Silicone insulation - ANSWER-- Advantages: w/p any known long term degradation.
Inert, biocompatible, and biostable.
- disadvantages: high friction coefficient (sticky), Handling damage, and size. Soft,
prone to damage during implant
Expanded Polytetrafluoroethylene ePTFE - ANSWER-- ePTFE is a gortex type material
that has been shown to improve the ease of extraction due to reducing the degree of
fibrous growth, especially on the shocking coils.
- the material is electrically inert and does not effect the DFTs.
-can be removed more easily than non- ePTFE leads*
- is a stable biomaterial with a chemical structure consisting of a carbon backbone with
flourine atoms which form a protective sheath, producing a chemically inert material with
low energy surface properties.
- made by mechanically stretching and orienting PTFE to create a porous material with
high tensile strength and flexibility.
Fluoropolymers (PTFE, ETFE) Insulation - ANSWER-- Advantages: inert, most
biocompatible, high tensile strength, small size
- Disadvantages: stiff when >0.0003", more prone to creep, difficult to manufacture w/o
pinholes
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