The Sinus Node

Within vertebrates, heart rate is established by the sinoatrial (SA) node of the heart. This is achieved through a series of action potentials which drives excitation of cardiac muscles and establishes a rhythmic pace (Fritz et al., 2011). However, there are numerous factors that can affect the SA nodes impact on heart rate, which are primarily related to the autonomic nervous system.

In the early 1920 the development of the electrocardiogram provided objective information about the hearts structure and function. The evolution of the ECG lead to new inventions that led to the 12-lead electrocardiogram (1).

Whenever someone comes into the Emergency Department of a hospital with chest pain, an electrocardiogram (ECG) is done. An ECG is a recording of the voltage pulses in the heart. These voltage pulses are waves of electrical current that cause the heart to beat. Before continuing our discussion, it is important to note that an electrical current is the flow of electrons whereas voltage is simply the potential those electrons have to do work if or when they are delivered.

Atrioventricular (AV) node: the area of the heart conduction system responsible for receiving impulses from the SA node via intermodal pathways and stimulate the ventricles to contract

According to Central Maine Medical Center policy on temporary pacing, the pacer works to “deliver direct electrical stimulation to stimulate the myocardium to depolarize which initiates a mechanical contraction when the sinoatrial node is unable to do so.” Temporary pacing of the heart is indicated in multiple circumstances. It is primarily used after a valve surgery. However the pacer is also used for the maintenance of inadequate heart rate and rhythm during surgery, postoperative recovery, cardiac catheterization, coronary angioplasty, certain drug therapies that cause bradycardia and before implantation of a permanent pacemaker. It can also be used to stabilize heart beats after a myocardial infraction.

The normal, healthy heart has its own pacemaker that regulates the rate that the heart beats. However, some hearts don't beat regularly. A pacemaker can sometimes correct the problem. A pacemaker is a small device that sends electrical impulses to the heart muscle to maintain a suitable heart rate and rhythm. A pacemaker may also be used to treat fainting spells (syncope), congestive heart failure, and hypertrophic cardiomyopathy. It is a small box surgically implanted in the chest cavity and has electrodes that are in direct contact with the heart. First developed in the 1950s, the pacemaker has undergone various design changes and has found new applications since its invention. Today, pacemakers are widely used, implanted in tens of thousands of patients annually.

Having a implantable cardioverter-defibrillator put in your body. This is a device that gives the heart a shock when it beats too fast. It helps change a fast heart beat into a normal heart beat.

Robinson, C., & Ferguson, G. (1996). Electroconvulsive therapy machines. Advances in Psychiatric Treatment, II, 24-31. Retrieved from http://apt.rcpsych.org/content/aptrcpsych/2/1/24.full.pdf

The SA node is the primary pacemaker of the heart. It starts the heartbeat by spontaneously contracting, causing the rest of the heart to contract in a wave.

The initial model of the pacemaker monitored as well as controlled the patient’s heartbeat. A pacemaker consists of electrodes, battery and a computerized generator. The main purpose of the pacemaker is to stabilize your heart rhythm. If there’s a change in the rhythm of your heartbeat and it is inconsistent with the normal values then the computerized generator receives a stimulus, which in turn produces electrical signals. These electrical signals are further transmitted to the heart through electrical wires whereby they help maintain a normal heart rhythm.

The pacemaker of the heart, the sinoatrial (SA) node, generates the impulses that trigger the contractions of the heart chambers. In a very sequential, coordinated rhythm at a rate of 75 times per minute, it depolarizes faster than the other pacemaker cells of the heart preceding them with their impulses. Located in the superior right atrium, these spontaneously depolarizing myocytes trigger a depolarization wave, via gap junctions, to the left atrium and the atrioventricular (AV) node, lying in the inferior right atrium. Gap junctions, in the intercalated discs, allow the rapid transmission of ions to adjoining myocytes. Furthermore, the electrical signal can conduct through the adjoining myocytes, allowing it to operate as one functional

`The frontal sinus is located above the eye. They are air spaces lined with mucous membrane. The ethmoid is a pair of paranasal sinuses. They help filter the air that goes into the nasal cavity. These are located in the ethmoid bone, which has ethmoidal air cells. There is three groups of ethmoidal air cells. They are the posterior, middle, and anterior. They are made up of a lot of cavities that have thin walls that are in the ethmoidal labyrinth and are finished by the maxilla, frontal, lacrimal, palatine, and sphenoid bones. The lips are mobile structures that surround the opening of the mouth. They have skeletal muscles and sensory nerves that are useful in judging textures of food and temperature. The lips mark the boundaries between the skin of the face and the mucous membrane that lines the alimentary canal. The trachea is hollow tube that connects the larynx and the bronchi of the lungs. It provides airflow to and from the lungs for respiration. The lungs is where the air you inhale goes and it lets go of waste air like carbon dioxide. The diaphragm is a dome shaped muscle and tendon that plays a vital role in the breathing process. It is

• sinoatrial node- is the impulse-generating (pacemaker) tissue located in the right atrium of the heart, and thus the generator of normal sinus rhythm.

An artificial pacemaker is an electronic surgically-implanted device to regulate slow or erratic heartbeats. They are indicated for the patients with symptomatic bradycardia. A pacemaker is a small electronic pulse generator sealed in a titanium case with one (monopolar) or more usually now, two (bipolar) electrode leads

“ Nowadays there are about 3 million people worldwide with pacemakers, and each year 600 000 pacemakers are implanted. With rare exception, implantation of a pacemaker does not change the recipient’s activities or