Chronic Kidney Disease and Your Heart

According to the Center for Disease Control (CDC), heart disease is the leading cause of death in the United States and stroke is the third leading cause. Both of these conditions are caused by cardiovascular disease. Cardiovascular disease is common in people with chronic kidney disease (CKD) regardless of age, stage of kidney disease or if they’ve had a transplant. In addition, underlying conditions that cause renal disease, such as high blood pressure and diabetes, put people at risk for cardiovascular disease.

What is cardiovascular disease?

The adult human heart is about as big as two clenched fists and weighs about 11 ounces. It pumps oxygen and nutrient-rich blood through the arteries to vital organs, including your brain and tissues. Cardiovascular disease (CVD) is an umbrella term used to describe conditions that affect the heart and blood vessels (also known as the vascular system).

Cardiovascular disease can affect the function of the heart and the blood vessels, leading to serious health problems. A breakdown or interruption in oxygen supply to your organs will cause damage and possibly death. If you suffer from CVD, life-sustaining organs like your heart and brain are at risk.

Many chronic kidney disease patients suffer from heart disease, which is a type of CVD. Heart disease is a general term to describe any cardiovascular disease that affects the heart and/or the blood vessels in the heart. The following conditions are considered heart disease:

Coronary artery disease: This disease affects the arteries that supply the heart muscle with blood. If these arteries become blocked and the flow of blood is restricted to the heart, a heart attack may occur. Coronary artery disease can also lead to other problems such as chest pain (angina).

Heart attack: A heart attack occurs when a coronary artery, which carries blood and oxygen to one section of the heart muscle, is blocked. Without oxygen, this portion of the heart muscle begins to die and there is a feeling of pain or pressure in the chest. The portion of the dead muscle is later replaced by scar tissue.

Heart failure: A strong heart pumps blood throughout the body. A weakened heart is unable to do an efficient pumping job. If a heart cannot pump enough blood, heart failure may occur.

The following types of cardiovascular diseases that affect the blood vessels may impact people with renal disease:

Atherosclerosis: When arteries become clogged with an accumulation of cholesterol, fat and calcium (also known as plaque), this can lead to a condition called atherosclerosis. As plaque forms along the walls of the artery, the artery becomes less flexible. Also, the passageway inside the artery becomes smaller, making it difficult for blood to flow freely. A stroke or heart attack can occur if the accumulation of plaque is thick and the artery becomes so clogged that blood cannot get through it.

High blood pressure: High blood pressure (also known as hypertension) occurs when blood is pushed through the arteries at an increased pressure. When blood pressure is too high, the walls of the arteries can become weakened and also cause complications such as stroke or heart attack.

Chronic kidney disease and the risk of cardiovascular disease

Complications that develop from chronic kidney disease, as well as the underlying conditions that cause chronic kidney disease, can put you at risk for cardiovascular disease. The following are complications that develop from renal disease and can lead to cardiovascular disease:

Anemia: Anemia is when your body does not have enough red blood cells. The kidneys manufacture a hormone called erythropoietin, which tells the bone marrow to make more red blood cells. If your kidneys are damaged, your erythropoietin levels can fall, and your body will not make enough red blood cells.

Several studies have shown that anemia can be related to cardiovascular disease. Red blood cells contain a protein called hemoglobin, which helps transport oxygen throughout the body. Fewer red blood cells mean less oxygen goes to the body’s tissues and organs. If a body is not getting enough oxygen, the heart is not getting enough oxygen either. Without adequate oxygen to the heart muscles, a person may be susceptible to a heart attack. Anemia can also cause the heart to pump more blood in order to circulate enough oxygen throughout the body. As the heart works harder, the muscle in the left lower chamber of the heart can develop thick walls. This is a condition called left ventricular hypertrophy (LVH). LVH can increase the chance of heart failure.

High blood pressure: The kidneys make renin, which is an enzyme that helps control blood pressure. When blood pressure is too low, healthy kidneys release renin to stimulate different hormones that increase blood pressure. Damaged kidneys may release too much renin, which can lead to high blood pressure. High blood pressure increases the risk of heart attack, congestive heart failure and stroke.

High homocysteine levels: Homocysteine is an amino acid normally found in blood. Healthy kidneys regulate the amount of homocysteine in the blood and remove any excess. But damaged kidneys cannot remove the extra homocysteine. High levels of homocysteine have been linked to the build up of plaque in the blood vessels, which can lead to cardiovascular diseases such as atherosclerosis (when fatty material deposited along the artery walls gets hard and blocks the blood flow) and coronary artery disease. High levels of homocysteine may also damage the lining of the blood vessels, making a person prone to blood clots which increase the risk of stroke and heart attack.

Calcium-phosphate levels: Different studies have suggested a link between the calcium and phosphorus levels in patients undergoing dialysis and the hardening of the coronary arteries. Healthy kidneys help keep calcium and phosphorus levels in balance. But damaged kidneys cannot do this. Often, there is too much phosphorus and calcium in the blood. When this happens, there is a risk for coronary artery disease.

Diabetes and high blood pressure are the two leading causes of kidney disease. Here is how each can affect your heart and lead to cardiovascular disease:

Diabetes: Diabetes is a condition where excess sugar remains in the bloodstream. This sugar can damage the blood vessels not only in the kidneys but elsewhere in the body, including the major blood vessels that feed the muscles of the heart.

High blood pressure: Not only is high blood pressure a complication from diabetes, it is also a cause of kidney disease. Too much pressure can weaken the walls of the blood vessels, which can lead to a stroke.

Treating cardiovascular disease in people with kidney disease

Whether your cardiovascular disease is caused by complications of your kidney disease or by the underlying cause of your kidney disease, it's important to be aware of the impact it can have on your overall health. Treating the cause of your cardiovascular disease and keeping other conditions like chronic kidney disease, diabetes and high blood pressure under control will help you feel better.

Your kidney doctor will monitor the health of your kidneys and check for signs of cardiovascular disease. You will also be monitored for complications like anemia and high blood pressure. Part of your treatment program may include taking certain medications to treat these complications, as well as treating any calcium or phosphorus imbalances in the body. Your doctor will also refer you to a renal dietitian, who will work with you to create a kidney-friendly and heart-friendly diet that is low in cholesterol and saturated fats.

If you have diabetes and/or high blood pressure, your kidney doctor will work with your family doctor and renal dietitian to treat both conditions. Your treatment plan may include a combination of medication and diet. Managing your diabetes and blood pressure levels in the early stages of kidney disease will help slow the damage to your kidneys as well as reduce your risk for cardiovascular disease.

Your doctor may also recommend exercise as part of your treatment program. Based on your physical condition, age and other factors, your doctor will suggest activities that are right for you. If you smoke, your doctor will recommend that you stop. Smoking increases your risk of cardiovascular disease, and can cause other complications.  

Chronic kidney disease affects more than your kidneys; it can put vital organs such as your heart at risk. Managing your renal disease and the underlying causes of your kidney disease, such as diabetes and high blood pressure, can reduce your chances of developing cardiovascular disease.