Genetic disorder of lipid metabolism causing accumulation of cholesterol, thus increasing the risk of cardiovascular diseases.
Hypercholesterolemia; Low-Density-Lipoprotein (LDL) Receptor Disorder.
Estimated incidence is 1:500 of general population.
In most cases the patients are heterozygotes. They have a defective LDL receptor that has no activity or up to only 10% of normal activity; the other allele is normal, so globally the total activity is 50 to 60%. Afterward there is an increase in plasmatic level of LDL that can infiltrate arterial vessels and cause endothelial damage, platelet aggregation, atherosclerosis, and, ultimately, ischemic cardiac disease.
Diagnosis is made in the presence of isolated elevation of cholesterol without concomitant elevation of triglycerides. Also, in the familial type, the total cholesterol concentration is more elevated than with other causes of elevated cholesterol. Finally, the presence of xanthomas on tendons is pathognomonic of this type of hyperlipidemia.
Patients are often detected at birth through the blood sample taken from the umbilical cord, in which LDL levels are two to three times normal for heterozygotes and six to eight times normal for homozygotes. Levels remain high throughout life, but symptoms appear around 30 to 40 years of age in the case of heterozygotes. The symptoms associated with this disease are the result of accelerated coronary atherosclerosis causing myocardial infarctions. The other major finding in this disorder is the presence of xanthomas deposition on tendon, eyelid, and cornea. In the homozygote form, the manifestations are the same but appear earlier, with ischemic lesions occurring as early as 18 months of age and death around 20 years of age. Treatment is a strict diet with low saturated fat and high polyunsaturated fat. If diet alone is insufficient, patients are placed on pharmacologic treatment.
Precautions before anesthesia
Perform a thorough cardiac evaluation before taking the patient to the operating room. If patient is on drug therapy, obtain liver function tests and glycemia and uric acid levels.
Consider these patients as affected with coronary artery disease until proven otherwise and thus avoid any increase in cardiac oxygen consumption pre- and postoperatively. Plan for adequate pain relief after surgery, knowing that most adverse events occur in the first three postoperative days. A bed in the critical care unit may be advised for closer followup during the immediate postoperative period. Invasive monitoring is warranted for surgeries with major hemodynamic fluctuations.
Some of the drugs used for treatment of this disease may cause hepatotoxicity, so halothane should be avoided. Drugs eliminated via the kidney should ...