Medtronic has established itself as the clear market leader in the medical devices industry and continues to be a leader in innovation. It was the first company to develop the technology to support cryoablation and its development of the Freezor Cardiac CryoAblation Catheter demonstrates that it continues to improve its technology to provide the best patient care. The Freezor Cardiac CryoAblation Catheter is primarily indicated for paroxysmal atrial fibrillations, specifically atrioventricular nodal reentrant tachycardia (AVNRT), and it provides a number of advantages over the current standard of care. Cryoablation with the Freezor Cardiac CryoAblation Catheter eliminates complications associated with RF ablation, increases stability and control, …show more content…
and produces immediately reversible lesions. Together, these features make the Freezor Cardiac CryoAblation Catheter the superior product and allow Medtronic to continue to dominate the growing cryoablation market. AVNRT is a type of arrhythmia that originates from the AV node in the heart. The heart is divided into four chambers: the right atrium, right ventricle, left atrium, and left ventricle. Depolarizing signals originate from the SA node in the left atrium and travel downwards through the AV node to the ventricles. The AV node delays the signal before being transmitted throughout the ventricles, allowing the heart to beat correctly. Patients with AVNRT have two pathways that connect to the AV node and forms a portion of the reentrant circuit. The AV node has both a fast and a slow pathway from the atria to the ventricles. Signals propagate through the fast pathways first, followed by those in the slow pathway. By the time the slow pathway signal reaches the end of the AV node, the fast pathway has entered its refractory period. The slow pathway has a shorter refractory period than the fast pathway, and is central to AVNRT’s pathophysiology. 90% of the AVNRT patient population has antegrade conduction in the slow pathway, and retrograde conduction in the fast pathway, as shown in Figure 1. Premature ventricular stimulation is what induces AVNRT in the remaining 10% of patients. Atypical AVNRT can also take place in the opposite direction with retrograde conduction occurring in the slow pathway and antegrade conduction in the fast pathway. AVNRT is diagnosed with an electrocardiogram (ECG/EKG) by monitoring the QRS complex.
In a normal ECG reading, the components are P, Q, R, S, and T. P correspond to atrial depolarization, QRS corresponds to the ventricle depolarization and atrial repolarization, and T corresponds to ventricular repolarization. The whole process is a complete beat of the heart. There are a few variants of AVNRT, but the most typical presentation is when the atrium has another depolarization at or near the onset of the ventricular depolarization. This commonly leads to the P wave in the ECG to be masked by the QRS complex (Figure …show more content…
2). If the patient is experiencing recurring palpitations, the physician may recommend a Holter monitor to monitor the heart for 24 hours or longer with an ECG. On rare occasions, palpitations that are disabling but infrequent may warrant an insertion of a small microchip device such beneath the skin. This continuous recording of the heart’s activity allow a physician to distinguish AVNRT from other tachycardia forms such as atrial flutter, atrial fibrillation, and sinus tachycardia. Physicians may also order blood tests to diagnose patients who experience palpitations. Imbalance in an individual’s electrolytes like potassium, calcium, and magnesium may indicate a predisposition to AVNRT. Thyroid Function Tests (TFTs) can also check for overactive thyroid levels, which would indicate an increased risk for AVNRT. Approximately 0.1% to 0.2% of people are afflicted with AVNRT worldwide. Of these individuals, about 66% are women who developed the condition between late adolescents and 40 years of age. Most likely due to the high success rate of current treatment , data regarding AVNRT related mortalities is scarce. However, the mortality rate of ablation-related complications is 0% to 0.2%. Despite the relatively high incidence of AVNRT radiofrequency (RF) ablation, the current treatment for arrhythmias has a 90% to 97% success rate. Radiofrequency ablation works by generating heat at the tip of the catheter by means of radiofrequency to lesion target cells. In order to mitigate damage to the body, a conduction pad with a large surface area is placed on the opposite side of the heart. With a larger surface area, it draws in currents produced by the catheter over a large surface area so that the heat is dispersed and does not harm the body. An alternative treatment for AVNRT currently being explored is the use of cryoablation, the process of using freezing temperatures to eliminate unwanted cells. This method takes advantage of refrigerants to remove the heat and freeze the tissue. The freezing disrupts the myocardial articulature and organelles. AVNRT is present when a reentry circuit develops adjacent to the AV node.
Both the fast and slow pathways arise in the right atrium, but the slow pathway is the target for the cryoablation therapies. Since the AV node is a special conduction area that conducts electrical impulses from the atria to the ventricles, ablating tissue neighboring the AV node carries a risk of creating heart block. Heart block disrupts regular conduction of electrical impulses from the atria to the ventricles. Physicians opt for the cryoablation technique when there is a complete heart block concern; freezing tissue surrounding the AV node decreases the risk of heart block due to its ability to create lesions that are initially reversible. Cryoablation procedures are more effective in the younger population less than 40 years of age because incidence of recurrence increases with
age. Cryoablation treats cardiac arrhythmias by freezing the cardiac tissue that causes abnormal electrical impulses. A catheter is first inserted in a small cut in the patient’s leg skin; it is then inserted into a blood vessel leading to the heart. The tip of the catheter is placed against the tissue in the heart that is causing irregular heartbeats. There is a control console that is pressurized to supply cold liquid to the catheter tip in the heart. This decreases the temperature of the tissue that touches the catheter tip and “ablates” or destroys the tissue interfering with electrical signals. The Freezor Cardiac Cryoablation Catheter is a flexible, single-use catheter designed to ablate cardiac tissue. The device can be steered and
Transcatheter aortic valve replacement or TAVR is the latest technology used principally for the treatment of aortic stenosis, a condition in which one of the major valves of the heart, the aortic valve, becomes tight and stiff, usually as a result of aging (3). Since many patients who need aortic valve replacement for aortic stenosis are too sick to undergo major valve replacement surgery, they are unable to get the treatment they need. With the transcatheter aortic valve, this issue is bypassed because this valve can be implanted in the heart by accessing the patient’s heart through an artery in the groin. The valve can be inserted through a wire that can be pushed to the heart, and the old valve is simply pushed to the side when the new valve is implanted. This technology has been in use in the US with Edwards’ Sapiens valve since 2011 and has saved the lives of many patients with aortic stenosis (4).
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.
The normal core temperature in adults ranges between 36.5°C and 37.5°C and hypothermia can be defined as core body temperature less than 36°C.(ref 1)
622 Y. When the AV node receives the signal, it fires and causes the ventricles to depolarize, this is known as the QRS Complex. The atria also repolarizes during this phase. Specifically in the QRS Complex, during the Q wave, the interventricular septum depolarizes, during the R wave, the main mass of the ventricles depolarizes, and during the S wave, the base of the heart, apex, depolarizes. After the QRS Complex, the S-T segment can be identified as a plateau in myocardial action potentials and is when the ventricles actually contract and pump out blood to the pulmonary and systemic circuits. The final phase of the heartbeat is the T wave and this is when the ventricles repolarize before the relax, ventricular diastole, EKG Video Notes and pg. 671 D. These phases represent the cardiac cycle, which is the time and events that occur from the beginning of one heartbeat to the beginning of the next heartbeat. In this lab, the first EKG that I took was my regular heartbeat during rest. In this recording, I was able to see the P wave, followed by the QRS Complex and the T wave as well. Everything looks pretty normal, but the T wave does go a little lower than normal and I believe this is due to the fact that I was diagnosed with sinus bradycardia
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).
In this article, it tells how an EKG scan is on grid paper and each small block, which is one millimeter (mm) long, represents 0.04 seconds and each larger box, which is five millimeters long, represents 0.2 seconds. On a EKG scan, the voltage of the heart is measured in millivolts (mV) along the y-axis. On the scan grid, ten millimeters is equal to one millivolt. According to this source, in order to calculate the beats per minute (BPM), one divides the number of number of large boxes between each heart beat (QRS wave) in 300 small boxes. However, that used for a more consistent and steady heart rate. For a more varied and irregular rhythm, one has to count the number of QRS waves in six seconds and then multiply that number by ten. For an example, if there are eight QRS waves, then the estimated heart rate would be 80
There are four different categories of treatment: lifestyle changes, surgical procedures, non-surgical procedures, and medications. Lifestyle changes include having a healthy diet; increasing physical activity; eliminating cigarettes, alcoholic beverages, and illicit drugs; and getting enough rest and sleep; losing excess weight. These lifestyle changes are to lower the patient’s blood pressure, cholesterol, and reducing any other future medical conditions. There are also surgical options to help cure, prevent, or control cardiomyopathy. Surgical method include a septal myectomy, surgically implanted devices, and a heart transplant. A septal myectomy is used to specifically treat hypertrophy cardiomyopathy which is where the heart muscle cells enlarge and cause the walls of the ventricles to thicken. The thickening of the walls may not affect the size of the ventricles but instead may affect the blood flow out of the ventricle. Usually along with the ventricles swelling, the septum in between the ventricles can become enlarged and block the blood flow causing a heart attack. When medication is not working well to treat hypertrophic cardiomyopathy, a surgeon will open the chest cavity and remove part of the septum that is blocking blood flow. Surgically implanted devices include a pacemaker, a cardiac resynchronization therapy device, a left ventricular assist device, and an implantable
Maintaining normal core body temperature (normothermia) in patients within perioperative environments is both a challenging and important aspect to ensure patient safety, comfort and positive surgical outcomes (Tanner, 2011; Wu, 2013; Lynch, Dixon & Leary, 2010). Normorthermia is defined as temperatures from 36C to 38C, and is maintained through thermoregulation which is the balance between heat loss and heat gain (Paulikas, 2008). When normothermia is not maintained within the perioperative environments, and the patient’s core body temperature drops below 36C, they are at risk of developing various adverse consequences due to perioperative hypothermia (Wagner, 2010). Perioperative hypothermia is classified into three
..., Welsh R, Feindel C, Lichtenstein S. Transcatheter aortic valve implantation: a Canadian Cardiovascular Society position statement. Can J Cardiol. 2012;28:520-8.
Cyanotic heart disease is a heart defect, present at birth that results in low blood oxygen levels. With a series of surgeries, this condition is usually tr...
Hypothermia protocol for the post cardiac arrest patient has been an evidence based practice of this therapy for about a decade now. This intervention, often used in the critical care setting, is now expanding to primary emergency responders as well. This paper will present some of the notable research that has been done on therapeutic hypothermia, and current use of this intervention.
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).
The study of cardio physiology was broken up into five distinct parts all centering on the cardiovascular system. The first lab was utilization of the electrocardiogram (ECG). This studied the electrical activities of the heart by placing electrodes on different parts of the skin. This results in a graph on calibrated paper of these activities. These graphs are useful in the diagnosis of heart disease and heart abnormalities. Alongside natural heart abnormalities are those induced by chemical substances. The electrocardiogram is useful in showing how these chemicals adjust the electrical impulses that it induces.
The company provides innovative solutions to combat postoperative conditions such as hypothermia. Medical research indicates that 60 to 80 percent of all postoperative recovery room patients are clinically hypothermic. Hypothermia is caused by a patient’s exposure to cold operating room temperatures that are required by surgeons to control infection, and for the personal comfort of the surgeon. Hypothermia can also be a result of heat loss due to evaporation of the fluids used to scrub patients, evaporation from exposed bowel, and breathing of dry anesthetic gases. Dr. Augustine’s personal experience in the operating room convinced him that there was a need for a new system to warm patients after surgery.
is the Kelvin scale. On the Kelvin scale absolute zero has a value of zero