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Diastolic Dysfunction

A High Blood Pressure Problem in the Heart

Mar 20, 2009 Michael Leff

High blood pressure can cause your heart muscle to thicken and pump ineffectively. You could develop congestive heart failure or have a heart attack.

High blood pressure can cause things like a Stroke (CVA), Transient Ischemic Attack (TIA), and other general circulatory problems. Something that may not be seen is the effect that it has on your heart. High blood pressure can effect your heart just as it would your brain; more than just a heart attack. High blood pressure stresses your heart out and can cause conditions like Congestive Heart Failure (CHF), coronary artery insufficiency, and problems in the aorta.

Contraction and Relaxation of the Heart

The heart has two distinct phases; systole and diastole. During systole the heart is contracting and expending energy that is supplied to it from the coronary arteries. During diastole the heart is relaxing and gaining oxygen and nutrients to prepare for the next contraction.

The main parts of the heart that pump blood out are the ventricles. The left ventricle pumps out to the aorta and the right ventricle pumps out to the lungs. The ultimate key here is that during diastole the coronary arteries are being fed energy requirements and the left ventricle is refilling.

When the heart must pump against higher pressures it must work harder, stretch more, and use more oxygen. If the heart has a dysfunction during the period of diastole the coronary arteries will not receive the needed material to energize it and the heart muscle stretches in order to pump against the increased resistance. The end result of this sequlae contributes to a condition called diastolic dysfunctio

Diastolic Dysfunction and Heart Disease

Diastolic dysfunction can result from a persistent hypertensive (high blood pressure) state. The physiology behind this is that as pressures within the circulatory system, the heart specifically, increase the heart must work harder and stretch more. During this time the heart muscle cells space out more, increase collagen deposits, and essentially thicken. As a result of this expansion the heart muscle essentially morphs and begins to act like a thick piece of rubber; losing its ability to contract and relax completely; reducing something called distendibility.

When distendibility is reduced the heart becomes an inefficient pump. Regardless of how much pressure your place in the left ventricle of the heart it cannot fill or eject blood completely, hence reducing your output.

When the blood cannot be removed efficiently it backs up into the top part of the heart (atria) and subsequently into the lungs (pulmonary congestion). If the flow backs up into the lungs it will affect the right side of the heart causing increased pressures within the venous system and deposit in the tissues (systemic congestion).

Blood Pressure Regulators in the body

Your body has a feedback system that basically tells it when to rest, sleep, speed up your heart, and increase your breathing and when to eat. These functions are controlled not only by the sensors that are strategically placed in your body but by the organs as well. Subsequently these organs will direct the heart to compensate for its needs and stretch more and use more oxygen.

An example is when there is not enough blood flow to the kidneys and the filtration rate drops it stimulates a system known as the Renin-Angiotensin system. This system causes the body to increase the blood pressure to maintain the filtration rate in the kidneys by means of sodium and water changes (retaining more).

Continual blood pressure screening and monitoring will help prevent not only a stroke but help prevent developing diastolic dysfunction. Establishing proper nutrition, regular exams at the physician and medications will help prevent a more global problem related to hypertension. Hypertension is not the only cause of diastolic dysfunction. If this condition arises your physician will order specific blood tests, an echocardiogram, x-ray, or a cardiac catheterization to determine the underlying cause.

References:

The Merck Manual

The Texas Heart Institute

The copyright of the article Diastolic Dysfunction in General Medicine is owned by Michael Leff. Permission to republish Diastolic Dysfunction in print or online must be granted by the author in writing.