BACKGROUND
Approximately 10% to 30% of patients with atrial flibrillation (AF) do not present structural heart disease or have a comorbidity such as hypertension. Atrial fibrillation is the most frequent arrhythmia in daily practice that occurs under diverse situations and its treatment should be based on the different scenarios of presentation. Severe population-based studies have found that AF is associated with greater morbidity and mortality and worse quality of life. It is the leading cause of arrhythmia-related hospitalizations with an important impact on medical costs.
Radiofrequency catheter ablation steadily progresses as an option therapy to cure atrial fibrillation. The indications of catheter ablation are increasing due to a greater understanding of the physiopathological mechanisms, technological improvements and better outcomes. The Spanish registry reported that 1 out of 10 catheter ablations were indicated for AF. In the USA, AF is the most frequent condition undergoing catheter ablation in referral centers. How have we reached this point?
THE PROBLEM OF ANTIARRHYTHMIC TREATMENT
Drug therapy has proved to be ineffective to maintain sinus rhythm in patients with AF, with recurrence rates between 40% and 80%. Class I antiarrhythmic drugs are ideal for patients without structural heart disease or with mild conditions due to a lower proarrhythmic risk and better tolerance; yet, the efficacy if these agents is < 40%. In the AFFIRM and RACE studies, the group of patients without structural heart disease was small, and only 30% to 60% were still in sinus rhythm during follow-up. A meta-analysis comparing the efficacy of antiarrhythmic agents to maintain sinus rhythm showed that the proportion of patients in sinus r...
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16. Garcia-Bolao I, Diaz-Infante E, Gallego AM; Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias. Spanish Catheter Ablation Registry. Seventh official report of the Spanish Society of Cardiology Working Group on Electrophysiology and Arrhythmias (2007). Rev Esp Cardiol 2008;61:1287-97.
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There are several different heart problems that show up as an abnormal EKG reading. For example, a heart block can occur when there is a delay in the signals coming from the SA node, AV node, or the Purkinje fibers. However, clinically the term heart block is used to refer to an AV block. This delays or completely stops communication between the atria and the ventricles. AV block is shown on the EKG as a delayed or prolonged PR interval. The P wave represents the activity in the atria, and the QRS complex represents ventricular activity. This is why the PR interval shows the signal delay from the AV node. There are three degrees of severity, and if the delay is greater than .2 seconds it is classified as first degree. Second degree is classified by several regularly spaced P waves before each QRS complex. Third degree can be shown by P waves that have no spacing relationship to the QRS complex. Another type of blockage is bundle branch block. This is caused by a blockage in the bundle of His, creating a delay in the electrical signals traveling down the bundle branches to reach the ventricles. This results in a slowed heart beat, or brachycardia. On an EKG reading this is shown as a prolonged QRS complex. A normal QRS is about .8-.12 seconds, and anything longer is considered bundle branch block. Another type of abnormal EKG reading is atrial fibrillation, when the atria contracts very quickly. On the EKG this is shown by no clear P waves, only many small fibrillating waves, and no PR interval to measure. This results in a rapid and irregular heartbeat. On the other hand, ventricular fibrillation is much more serious and can cause sudden death if not treated by electrical defibrillation.
In this lab, I took two recordings of my heart using an electrocardiogram. An electrocardiogram, EKG pg. 628 Y and pg. 688 D, is a recording of the heart's electrical impulses, action potentials, going through the heart. The different phases of the EKG are referred to as waves; the P wave, QRS Complex, and the T wave. These waves each signify the different things that are occurring in the heart. For example, the P wave occurs when the sinoatrial (SA) node, aka the pacemaker, fires an action potential. This causes the atria, which is currently full of blood, to depolarize and to contract, aka atrial systole. The signal travels from the SA node to the atrioventricular (AV) node during the P-Q segment of the EKG. The AV node purposefully delays
Supraventricular tachycardia (SVT) is a heart condition where the heart beats irregularly due to electrical abnormalities. It is fairly common, especially in children and women, yet unfamiliar to most people who are not diagnosed with it. There are three types of SVT: atrioventricular nodal re-entry tachycardia, atrial tachycardia, and Wolff-Parkinson-White syndrome. All three types have the same symptoms during episodes, which can last from seconds to hours and include palpitations, fatigue, dizziness, etc. However, the three types have different causes, all of which are unknown. To detect this condition an electrocardiograph is typically used. It compares the waves of the patient’s heart to a normal heart’s waves. Vagal maneuvers are
Fibrillations are caused by rapid, irregular contractions and may be useless for pumping blood. A defective in the SA node may result in ectopic focus causes abnormal pacemaker takes over. If the AV node takes over the junctional rhythm the heart will run at a pace of 40 to 60 beats per minute. If a defective AV node occurs, it may result in partial or total heart block and few or no impulses from the SA node reach the
Atrial fibrillation (AF) is a cardiac arrhythmia. It is the most common arrhythmia and it has implications for patients and anaesthetists alike. The anaesthetist must take into consideration the physiological and pharmacological implications of this common arrhythmia.
Cardiac dysrhythmias come in different degrees of severity. There are heart conditions that you are able to live with and manage on a daily basis and those that require immediate attention. Atrial Fibrillation is one of the more frequently seen types of dysrhythmias (NIH, 2011). The best way to diagnosis a heart condition is by reading a cardiac strip (Ignatavicius &Workman, 2013). Cardiac strips play an chief part in the nursing world allowing the nurse and other trained medical professionals to interpret what the heart is doing. In a normal strip, one can clearly identify a P wave before every QRS complex, which is then followed by a T wave; in Atrial Fibrillation, the Sinoatrial node fires irregularly causing there to be no clear P wave and an irregular QRS complex (Ignatavicius & Workman, 2013). Basically, it means that the atria, the upper chambers of the heart, are contracting too quickly and no clear P wave is identified because of this ‘fibrillation’ (Ignatavicius & Workman, 2013).
To understand the complications that occur in the heart when dealing with AF, one must first understand how the heart functions and how it sends the electrical signals that cause the heart to beat. In the upper right chamber of the heart, known as the right atrium, electrical signals are sent from the sinoatrial (SA) node through the electrical impulses known as autorhythmic cells. These autorhythmic cells essentially make the heart beat because they begin the electrical impulses that cause the heart to pulse in a rhythmic pattern. The right atrium fills with blood and then uses the electrical impulse created by the SA node to push the blood to the lower right chamber of the heart known as the right ventricle. The autorhythmic cells are sent through the atriums of the heart, which causes it to contract. That electrical impulse arrives at the atrioventricular (AV) bundle in a lower part of the right atrium. The (AV) bundle uses these electrical impulses to separate the tricuspid valves to allow blood from t...
A heart attack (myocardial infarction) is the death of heart muscle due to the loss of blood supply. Usually, the loss of blood supply is caused by a complete blockage of a coronary artery by a blood clot. A coronary artery is an artery that supplies blood to the heart muscle. Death of the heart muscle causes chest pain and electrical instability of the heart muscle tissue. Electrical instability of the heart causes ventricular fibrillation (chaotic electrical disturbance). Orderly transmission of electrical signals in the heart is important for the regular beating (pumping) of the heart. A heart undergoing ventricular fibrillation quivers, and can not pump or deliver oxygenated blood to the brain. Permanent brain damage and death can occur unless oxygenated blood flow is restored within five minutes.
This condition can be treated various ways depending on “the type and frequency of arrhythmias, associated symptoms…, and the presence of structural heart disease” (Cleveland Clinic, 2014). Some patients may not need treatment at all, since they show not symptoms, since sometimes this condition can be naturally eliminated over the first year of life, but may still be required to have regular schedule appointments with the physician so the patients can be monitored. If symptoms are prevalent, the different treatment methods include a pacemaker, defibrillator, surgery, and medicine.
If there are no blood clots, then electrical mapping will be performed to see where the false signals are coming from. Small wires are then stuck in blood vessels and thread to the heart. Once to the heart, the wires will target the area where the false signals are being sent and diminish it. (Treatment 3) If the AV node is the area sending out false signals, a pacemaker must be put in the AV node’s place (3). A pacemaker is an electrical device that sends out electrical signals telling the heart to beat (5). A more serious procedure done to treat atrial fibrillation is called the maze procedure.
I had the opportunity to observe two cardiac catheterization during clinical this week. A cardiac catheterization is a procedure to examine how well a patient heart is working. A thin tube called a catheter is inserted into a large blood vessel that leads to the patient heart. This procedure is done through angiography, a contrast dye visible X-rays is injected through the catheter. These X-ray images show the dye as it flows through the heart arteries, and shows where arteries are blocked (A H A, 2016).
It occurs because of repetitive electrical activity. This can occur in a patient with early or late heart failure, because there is damage to the heart tissue and the heart beats faster to try to supply the body with blood. Recommended treatment is elective cardioversion. Drugs used include an antidysrhythmic such as Mexitil or Sotalol (Ignatavicius &Workman, p. 728-729).
A microprocessor inside the defibrillator interprets (analyzes) the victim's heart rhythm through adhesive electrodes (some AED models require you to press an ANALYZE button). The computer analyzes the heart rhythm and advises the operator whether a shock is needed. AEDs advise a shock only to ventricular fibrillation and fast ventricular tachycardia. The electric current is delivered through the victim's chest wall through adhesive electrode pads.
Electrocution occurs when a small, specific amount of electrical current flows through the heart for 1 to 3 seconds. 0.006-0.2 Amps (i.e. 6-200 milliamps) of current flowing through the heart disrupts the normal coordination of heart muscles. These muscles lose their vital rhythm and begin a process known as ventricular fibrillation. Death soon follows.
The United States performed their own study in Minnesota of college and high school athletes trying to see the rate of sudden cardiac arrest. The athletes in Minnesota did not undergo ECG screening, unlike the athletes in Italy. I have compared the results of the two studies which have taken place around the same time period. I found out that there were 12 deaths in the Veneto, Italy region, where the screening took place, compared to only 11 deaths in Minneosta, where there was no screening. ( Corrado; Drezner; Basso; Pelliccia; Thiene p. 199 ) With that observation it is clear on why the United States do not perform the expensive ECG screening, like Italy requires.