Heart blocks are a serious and potentially life-threatening condition, and as healthcare professionals, you have a responsibility to provide the best possible care to your patients. By staying informed about the latest research and best practices, you can ensure that you’re always prepared to improve your patients’ lives, alleviate their suffering, and guide them on the road to recovery.
Join us as we explore the best practices in modern heart block management, honing your skills and deepening your commitment to compassionate, effective cardiac care.
Understanding Heart Blocks
A heart block, or atrioventricular (AV) block, is characterized by an interruption or delay in electrical signal transmission between the upper and lower chambers of the heart. Heart blocks can also occur in the sinoatrial (SA) node, but are not addressed here. This impaired conduction can cause irregular heart rhythms and interfere with optimal cardiac function.
Types Of Heart Blocks
A first-degree AV block is a minor delay in signal transmission that usually causes no symptoms and requires no treatment. Rarely, it indicates an underlying condition that needs to be treated. First-degree heart block may be detected on an electrocardiogram (ECG) as a prolonged PR interval.
Second-degree AV blocks can be divided into Mobitz type I (Wenckebach) and Mobitz type II. With Mobitz type I, there’s a progressive prolongation of the PR interval until an impulse fails to reach the ventricles. In Mobitz type II, the QRS complex abruptly stops without any change in the duration of the PR interval. Mobitz type II is associated with greater risks of symptoms or death and often requires more aggressive intervention.
Third-degree AV block, or complete heart block, occurs when no electrical signals are transmitted from the atria to the ventricles. This causes the atria and ventricles to beat and contract independently, resulting in the heart’s uncoordinated and inefficient pumping. Additionally, since the intrinsic ventricular heart rate is slower than normal, blood flow is inhibited. Third-degree heart blocks are serious and usually require immediate intervention, such as a temporary or permanent pacemaker, to restore synchrony between the atria and ventricles, maintain an adequate heart rate, and provide adequate cardiac output.
What Can Cause A Heart Block?
Numerous factors contribute to a heart block’s development, and it’s important to understand these causes. By addressing some of these factors, your patients can reduce their risk of developing a heart block and maintain a healthier cardiovascular system. Some of the main causes include:
- Fibrosis and calcification of the cardiac electrical system as we age (higher risk in the elderly).
- Heart attacks or coronary artery disease, which may cause damage to the electrical pathways in the heart.
- Cardiomyopathy weakens the heart muscle and increases susceptibility to heart block.
- Inflammatory diseases such as sarcoidosis and several others.
- Tick-borne infections such as Lyme Disease or certain other infections can also affect the electrical pathways in the heart.
- Elevated potassium levels and other electrolyte disturbances can affect electrical conduction in the heart.
- Severe obesity places significant stress on the cardiovascular system and increases susceptibility to heart problems, including heart block.
- Congenital conditions such as levo transposition and left atrial isomerism are associated with the development of AV block.
Evidence-Based Management Strategies For Heart Blocks
Evidence-based practices (EBPs) are problem-solving approaches that utilize the best available information and support clinical decisions to improve cardiovascular outcomes. Effective heart block management strategies include medications, pacemaker therapy, cardioversion and defibrillation, and surgical options.
Medications For Treating Heart Blocks
Proper use of medications plays a role in treating heart blocks. Below is a list of commonly used medications to treat different types of heart block:
- First and foremost, decrease or stop medications that can cause heart block. These may include beta-blockers, calcium channel blockers, and digoxin.
- Some antiarrhythmic drugs may need to be stopped or adjusted as they may cause heart block
- If the heart block occurs in association with atrial fibrillation or atrial flutter, then an anticoagulant may be used to reduce the risk of blood clots and strokes.
- If the heart block is caused by an inflammatory or infiltrative condition (e.g. autoimmune-mediated congenital heart block) then a corticosteroid may be administered.
- Antibiotics or antifungal medications may be prescribed if the heart block is due to infectious causes such as Lyme disease or endocarditis
It’s important to note that changes in medication or treatment of related cardiovascular diseases may alleviate symptoms of heart block. Therefore, physicians must carefully review each patient’s medical history and current medications before prescribing new treatments to treat the reported heart block.
Pacemaker therapy is a widely used and effective approach to treating various heart block types. Second-degree AV block, Mobitz II, and third-degree AV block universally need a pacemaker. It typically involves the insertion of small, thin wires through the veins underneath the collarbone, and positioning them into the heart. These wires are then attached to a small, battery-powered computer device that fits under the skin beneath the collarbone. The pacemaker is about the size of a silver dollar and twice as thick.
This device treats arrhythmias that cause the heart to beat too slowly or miss beats. Pacemakers help maintain a steady heart rhythm by sending electrical impulses to the heart muscles to ensure proper conduction and blood flow.
For example, some pacemakers coordinate the timing of beats between the upper and lower chambers of the heart as in the AV blocks we’re discussing. Other pacemakers synchronize blocks that occur in the conduction within the lower chambers of the heart. Dyssynchrony of the heart can be a complication of heart failure, a weak heart, or an acute myocardial infarction (AMI).
While pacemakers effectively manage the symptoms of AV block, it’s important to note that they don’t currently offer preventive or curative solutions for the underlying causes of heart block.
Cardioversion And Defibrillation
Although cardioversion and defibrillation are not used for heart blocks, I will mention them for completeness about devices.
Cardioversion and defibrillation restore normal heart rhythms in rapid or irregular heartbeats.
Cardioversion involves using a machine that delivers electrical shocks to the chest while monitoring the heart’s rhythm. This procedure is usually used when the heart beats very fast or irregularly, which can lead to complications such as fainting, stroke, heart attack, or sudden cardiac death. During cardioversion, the electrical shock is timed to the patient’s heartbeats.
Defibrillation is a more urgent procedure that delivers high-energy shocks to the heart as soon as the defibrillator’s shock button is pressed. This treatment is used for life-threatening arrhythmias such as ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT), in which the patient no longer has a pulse.
Overall, there are no surgical options to treat atrioventricular heart block. I will point out that in patients undergoing open heart surgery, pacemaker wires are attached to the outside of the heart and run through the front of the chest, to allow for cardiac pacing if a heart block develops. These wires are meant to be temporary and removed about a week later when the patient is felt to be stable.
Sometimes surgical-type procedures are performed at the time of placing a pacemaker From time to time cardiologists actually induce heart block at the time of putting in a pacemaker. This is referred to as an atrioventricular (AV) node ablation. This procedure involves destroying the AV node, which then blocks electrical signals between the atria and ventricles. This may be done for a patient who has fast heart rhythms that cannot be controlled with medications alone. The ablation prevents the heart from going too fast and the pacemaker prevents the heart from going too slow.
Lifestyle Changes To Support Heart Health
Lifestyle changes alone do not prevent heart block, but we would be remiss not to encourage heart-healthy behavior. Additionally, since heart block can be acquired, as in the case of infections like Lyme Disease, physicians and patients should be on the lookout for symptoms of heart block and obtain treatment.
Everyone benefits in both the short and long term from exercise, a healthy diet, and abstaining from smoking and excessive alcohol consumption.
Exercise And Physical Activity
By promoting regular physical activity and incorporating it into comprehensive heart block management strategies, you can help reduce the burden of heart disease. Some ways to promote physical activity in your patients include:
- Encourage at least 150 minutes of moderate-intensity or 75 minutes of intense aerobic exercise weekly.
- Recommend strength training at least two days per week that targets all major muscle groups.
- Encourage patients to incorporate physical activity into their daily routine, such as taking the stairs instead of the elevator or walking instead of driving short distances.
- Talk to your patients about the benefits of regular physical activity, such as reducing the risk of heart disease, strengthening the heart muscle, and controlling weight.
- Help your patients set realistic goals for physical activity and support them in achieving those goals.
- Consider referring patients with heart disease to a cardiac rehabilitation program for more structured physical activity support.
Diet And Nutrition
Consider the following dietary guidelines to prevent heart disease and premature death:
- Have them include plenty of fruits and vegetables in their diet. These foods are rich in fiber, vitamins, and minerals and can help lower blood pressure and reduce the risk of heart disease.
- Favor whole grains over refined carbohydrates such as white bread and pasta. Whole grains contain more nutrients and fiber, which can help regulate blood sugar levels.
- Avoid saturated fats, such as those in fatty meats, butter, and cheese, as they can raise cholesterol levels, leading to heart disease.
- Replace unhealthy fats with healthy ones using olive oil instead of butter, avocado instead of mayo, or cream sauces.
- Consume lean protein sources such as fish, skinless poultry, lentils, and beans instead of red meat.
Avoiding Smoking And Excessive Alcohol Use
Smoking is a primary contributor to heart disease and stroke, as it encourages plaque accumulation within the arteries, resulting in obstructions that impede blood flow. By quitting smoking, individuals can experience enhanced circulation and reduced blood pressure, lowering the risk of heart attacks and strokes.
Heavy alcohol consumption can also lead to high blood pressure, causing immediate consequences like cardiac arrhythmias or irregular heartbeats. These immediate effects can be detrimental to your patient’s overall cardiovascular health and may lead to more severe complications in the long run.
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