Transfusion medicine
Therapeutic apheresis
LDL apheresis
Author: Huy P. Pham, M.D., M.P.H.
Last author update: 1 March 2014
Last staff update: 26 November 2021
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Transfusion low density lipoprotein apheresis
Table of Contents
Definition / general | Instrumentation | Epidemiology | Vascular access | Indications | Volume exchanged and technical details | Adverse events | Laboratory | Treatment | Additional referencesCite this page: Pham HP LDL apheresis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/transfusionmedLDL.html. Accessed April 19th, 2024.
Definition / general
- LDL apheresis: removal of LDL ("bad" cholesterol) by separating whole blood into its components and then selectively removing LDL from plasma by filtration / absorption; see guidelines at Circulation 2014;129:S1
Instrumentation
- Liposorber (Kaneka Pharma America):
- Whole blood is anticoagulated with heparin and then plasma is separated and run over a dextran sulfate column (U.S. Food and Drug Administration: Liposorber® LA-15 System [Accessed 28 January 2021])
- Typically processes 3 blood volumes, resulting in 56 - 65% reduction in LDL
- Plasmat Secura (B. Braun Medical):
- Can also precipitate the LDL heparin complex (B.Braun Medical: LDL Apheresis Therapy [Accessed 1 November 2017])
- LDL typically decreases by 67% after each treatment
- Both instruments are U.S. FDA approved to reduce LDL cholesterol
- There is minimal impact on HDL ("good") cholesterol
Epidemiology
- Familial hypercholesterolemia:
- High LDL levels from birth secondary to genetic mutation in ApoB / E (LDL) receptor
- Autosomal dominant
- Associated with early LDL deposits in tendons forming xanthomata; also early onset coronary artery disease
- Patients with 2 mutations have more severe disease (OMIM: Hypercholesterolemia, Familial [Accessed 1 November 2017])
- Lipoprotein(a) hyperlipoproteinemia:
- Lipoprotein(a) is a modified LDL unit that is coupled to apolipoprotein A via a disulfide bond
- Excess lipoprotein(a) can lead to accelerated atherosclerosis (OMIM: Apolipoprotein(a); LPA [Accessed 1 November 2017])
- Refsum disease:
- Autosomal recessive disorder that results in tetrad of abnormalities:
- Retinitis pigmentosa, peripheral neuropathy, cerebellar ataxia and elevated protein levels in cerebrospinal fluid, without an increase in the number of cells
- Most common presenting symptom is night blindness (OMIM: Refsum Disease, Classic [Accessed 1 November 2017])
- Treat by removing excess phytanic acid plus dietary modification (avoid dairy)
- Autosomal recessive disorder that results in tetrad of abnormalities:
- Sudden sensorneurial hearing loss:
- Multiple etiologies, including elevated cholesterol or fibrinogen, which compromises the terminal blood supply to inner ear (cochlea or cochlear nerve), causing unilateral or bilateral hearing loss (National Institutes of Health: Sudden Deafness [Accessed 1 November 2017])
Vascular access
- LDL apheresis can be performed either with peripheral IV access or with a central venous catheter (CVC)
- However, chronic treatment and CVC is nearly always required; may begin at ages 6 - 7 years for homozygous familial hypercholesterolemia cases
Indications
- For therapeutic procedure, the American Society for Apheresis (ASFA) delineates LDL apheresis based on the acuity of the clinical presentation
- Familial hypercholesterolemia (FH) LDL apheresis homozygotes: Category I
- Familial hypercholesterolemia LDL apheresis heterozygotes: Category II
- Liprotein(a) hyperlipoproteinemia LDL apheresis: Category II
- Peripheral vascular diseases LDL apheresis: Category III
- Phytanic acid storage disease (Refsum disease) LDL apheresis: Category II
- Sudden sensorineural hearing loss LDL apheresis: Category III
Volume exchanged and technical details
- All LDL apheresis systems use heparin alone or in combination with citrate as its anticoagulant so must screen patients for history of heparin induced thrombocytopenia (HIT)
- The Liposorber instrument only uses heparin; citrate interferes with the interaction between the column and apoB lipoproteins
Adverse events
- Overall adverse event rate is approximately 11% with no difference between instruments
- Most are minor: post procedure bleeding, vomiting, hypotention, hypoglycemia
- Discontinue ACE inhibitor medication prior to adsorption LDL apheresis; it causes excess bradykinin accumulation, leading to hypotensive reactions; can use angiotensin receptor blockers (ARBs) as an alternative
- Longstanding LDL apheresis can lower vitamin B12, ferritin and transferrin, contributing to anemia and possible need for dietary supplements
Laboratory
- Direct measurement of LDL levels is infrequently performed
- LDL levels are usually calculated using the Friedewald calculation: LDL = Total Cholesterol - HDL - Triglycerides/5.0 (mg/dL) (MDCalc: LDL Calculated [Accessed 1 November 2017], Clin Chem 1972;18:499, Clin Chem 2009;55:888)
Treatment
- For FH, treatment can be lifelong to stabilize or improve coronary artery atherosclerosis
- Frequency of procedure is adjusted to maintain target LDL level
- Multiple LDL procedures are needed to reduce the time averaged LDL levels
- LDL level can decrease dramatically after single procedure but long term goal is > 60% reduction from baseline
