Risk Factors And Causes of Premature Ventricular Contractions

Premature ventricular contractions (PVCs) are additional heartbeats that originate in the ventricles or one of the two lower pumping chambers of the heart. These extra heartbeats disturb the regular heart rhythm, and they can make an individual feel a fluttering sensation in the chest. An occasional PVC in an otherwise healthy individual is relatively normal, however, frequent contractions may indicate an underlying heart condition that may require treatment. Often times, PVCs are asymptomatic, or they cause no noticeable symptoms. However, when they do it typically includes the sensation of pounding or jumping in the chest, missed or skipped heartbeats, increased awareness of the heartbeat, and fluttering in the chest. 

Diagnosis of frequent premature ventricular contractions by a physician is important to identify the underlying cause of them. The reason being that the same symptoms can manifest in other conditions including anxiety and anemia. Several causes and factors would increase an individual's risk of frequent premature ventricular contractions.

Decongestants And Antihistamines

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Decongestants and antihistamines are often used to treat congestion that occurs in colds, respiratory infections, and allergies. These medications can also trigger premature ventricular contractions. Congestion happens when the small vessels in the nasal lining become enlarged. This causes swelling in the nasal passages making it easier for phlegm to become clogged these areas. This is when many individuals would use a decongestant or an antihistamine to relieve these unpleasant symptoms. Decongestants work by constricting the enlarged vessels in the nose, and antihistamines work by blocking an inflammatory chemical called histamine. 

Although decongestants do well at relieving congestion symptoms, the vasoconstriction effects are not isolated to the nasal passages. This medication causes all of the blood vessels in the body to constrict, resulting in an increase in heart rate and blood pressure. Frequent use of antihistamines can put an individual at an increased risk of premature ventricular contractions because they interfere with sodium channels that regulate the heartbeat.

Increased Adrenaline In The Body

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Increased adrenaline in the body can cause an individual to experience premature ventricular contractions. Adrenaline or epinephrine, the fight or flight hormone, is released by the adrenal glands. The primary function of adrenaline is to physically prepare the body for sudden and or vigorous action in times of distress. Adrenaline is supposed to increase the blood pressure and heart rate, expand air passageways in the lungs, redistribute blood to the muscles, dilate the pupil of the eye, and change the metabolism to maximize glucose. 

Increased levels of adrenaline can be caused by general stressful situations, a threat, extreme activities like bungee jumping or riding a rollercoaster, a tumor in the adrenal glands, anxiety, post-traumatic stress disorder, and excitement. The physical effects of adrenaline on the body can disrupt the natural rhythm of the heartbeat in numerous ways. One of the ways it may do so is by PVCs. When the heart is contracting and relaxing at a high rate due to high adrenaline levels, it has a higher likelihood of unintentionally contracting one of its chambers earlier than it should. When this happens in the bottom chambers or the ventricles, it is considered a premature ventricular contraction.

Coronary Artery Disease

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Any individual who has coronary artery disease is at a higher risk of experiencing regular and frequent premature ventricular contractions. Coronary artery disease happens when the arteries that supply the muscle tissues of the heart with oxygenated blood become narrowed, hardened, and clogged. This usually happens as a result of the build-up of cholesterol and fatty deposits on the inside lining of the arteries or endothelium. This can cause an obstruction in normal blood flow to the muscle tissues of the heart responsible for the contraction and relaxation of the heart chambers. Coronary artery disease doesn't have to cause a full blockage of blood flow to the heart in order to result in premature ventricular contractions. 

Even just a partial blockage can easily result in an irregular heart rhythm, including PVCs. Any degree of inadequate oxygen supply to the heart tissues can cause the nerve cells that control the heart muscle to function poorly. It can also cause the muscle tissues themselves to misinterpret signals that are sent from the nerves. Premature ventricular contractions and other heartbeat abnormalities will occur frequently when the nerve and muscle cells in the heart tissues do not work properly individually, or when they do not work together in unison correctly.

Heart Failure

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Heart failure can cause an individual to experience frequent premature ventricular contractions because of their reduced heart function. This happens when the heart muscle is unable to pump blood throughout the body effectively enough to support all of its functions. This inability can occur when the heart muscle becomes too weak in certain areas, becomes too hard or stiff in some areas, or both. Weakened parts of the heart muscle cannot contract strong enough to pump blood, and any stiffened parts of the heart will fail to fill up with enough blood to be pumped back out. Several factors can cause premature ventricular contractions to occur in individuals with heart failure. 

Structural changes, including fibrosis or scar formation, dilation of one or more chambers, myocardial stretch, and an alteration of the ionic cellular currents may all manifest as heart rhythm abnormalities. Fibrosis can place a physical barrier in the normal electrical pathways of the heart, which can result in PVCs. Heart failure can cause remodeling of sodium channels that control the heart rhythm, and this can interfere with normal ventricular contractions. Individuals who have heart failure that does not cause PVCs directly are still at an increased risk for them when additional risk factors become involved.

High Blood Pressure

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High blood pressure (hypertension) is a long-term condition where the force of blood against the walls of arteries is higher then it should be. Both the quantity of blood the heart pumps and the amount of resistance to the flow of blood within the arteries determine blood pressure. There are numerous ways hypertension can put an individual at an increased risk for premature ventricular contractions. Hypertension causes damage to the blood vessel walls, and this damage allows for cholesterol and other substances to penetrate into the vessels. This penetration is the main cause of clogged and narrowed coronary arteries that often manifest themselves through PVCs. 

In addition, high blood pressure makes the heart work harder, or it puts the heart under conditions of a heavy and continuous load of mechanical work to get blood pumped throughout the body. The carefully calibrated calcium control mechanism that regulates the beating rhythm of the heart can easily become unstable in such workload circumstances. When the calcium channel system is unstable, the electrical impulses that tell the heart chambers when to contract and relax become disrupted. Any disruption in these impulses can result in any heart arrhythmias, including premature ventricular contractions.

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