High cholesterol increases your risk for heart disease, but its relationship with your heart is more interconnected than just through arterial disease. High dietary and blood cholesterol leads to a malfunction in your heart's ability to fill with blood during rest, or diastole. High density lipoprotein, known as the body's good cholesterol because it helps remove excess cholesterol that contributes to arterial disease, also plays a factor in diastole.
Diastole
Diastole refers to the period of time your heart experiences between each beat. During this time your heart is both resting and expanding. During diastole, your ventricles are filling with blood to prepare for the next beat. A good-working heart fills adequately with blood, so that the needs of the body are met.
Cholesterol and Diastolic Dysfunction
A study published in "Circulation" in 2004 set out to explore the connection between high cholesterol levels and diastolic function. During 10 weeks, rabbits were fed a high-cholesterol diet. Both systolic as well as diastolic functioning was analyzed. High cholesterol caused by a poor diet induced a state of diastolic dysfunction that researchers termed "cholesterol cardiomyopathy." This condition caused inadequate filling during diastole.
Mechanism
Your heart is a muscle whose fibers have elastic and contractile properties. A theory known as the Frank-Starling Mechanism explains why diastolic dysfunction results in inadequate blood flow that mimics cardiomyopathy. The larger the stretch of the myocardium, the harder the heart is able to pump and release more blood, states the theory. Stretch is caused by the blood volume, so if diastolic function is impaired, then the myocardium is not aligned and blood pumped during a beat is inadequate. The study published in "Circulation" reflects this. The results of the study show that the hearts of the rabbits with hypercholesterolemia were unable to stretch and thus pumped less blood. Researchers believe this has to do with alterations in the effect of calcium inside the cardiac cells due to higher levels of cholesterol.
HDL Cholesterol
High density lipoprotein, referred to as the "good" form of cholesterol, also plays a role in diastolic functioning. According to a study published in the "American Journal of Hypertension" in 2003, low levels of HDL cholesterol also negatively impact diastolic functioning. In the study, 274 individuals with hypertension were analyzed. Echocardiograms to evaluate ventricular functioning as well as blood cholesterol levels were tested. Those with low HDL levels also experienced diastolic dysfunction.
Expert Insight
The relationship between high cholesterol and arterial disease is well-known, but these studies suggest that cholesterol influences more than just your arteries. Both high levels of bad cholesterol and low levels of good cholesterol can impede the diastolic functions of the heart. The best way to reduce your risk of heart disease from cholesterol is to follow a healthy diet and to get regular exercise.
References
- MedTerms.com: Diastole Defintion
- "Circulation"; Cardiac Systole and Diastolic Dysfunction After a Cholesterol-Rich Diet; Y. Huang, M.D., et al.; 2004
- "Exercise Physiology"; George A. Brooks, Thomas D. Fahey, Kenneth M. Baldwin; 2005
- "American Journal of Hypertension"; Influence of Low High Density Lipoprotein Cholesterol on Left Ventricular Hypertrophy and Diastolic Function in Essential Hypertension; Horio Takeshi; 2003
- National Heart Lung and Blood Institute: High Blood Cholesterol: What You Need to Know; June 2005
