Introduction
Slow pulses will need no treatment unless they cause symptoms [1]. There aren't any drugs available for speeding up the heart rate and therefore the only treatment, therefore, could be a pacemaker. In an emergency situation, a temporary pacemaker wire is inserted just above or beneath the clavicle and guided into the apex of the correct ventricle by X-ray control. A pacemaker box is attached and usually set at 3 volts and approximately 70 beats per minute. this could be rapidly inserted in an emergency situation and is life saving. For obvious reasons it can not be used on a permanent basis.
Practical, permanent pacemakers were developed within the 1960s. They contained nickel-cadmium batteries which lasted about two years. The pacemakers were quite bulky. With the advent of lithium batteries, small pacemakers lasting up to 10 years are now commonly used. the typical modern pacemaker is about the size of an old english pocket watch. The pacemaker electrode is inserted through the cephalic vein beneath the shoulder, and therefore the pacemaker box placed under the skin and on top of the muscle. Pacemakers are usually inserted underneath the left shoulder to avoid problems, like when shooting.
Coding System
• Generally, patients who don't have coordinated atrial activity (atrial flutter or atrial fibrillation) receive a VVI pacemaker (pace ventricles, sense ventricles, pacing is inhibited if native activity is sensed) [2].
• Other arrhythmias like sick sinus syndrome where there's no degree of AV block will need an AAIR pacemaker (pace atria, sense atria, inhibit pacing if they sense activity and are rate-responsive).
• However, in most cases these patients and every one those with dysfunction at and below the level of the AV node will receive a DDDR (pace both chambers, sense both, can both trigger and inhibit and are rate-responsive).
• Note that patients with sick sinus syndrome may later develop AV block.
• During surgery, electrocautery could also be sensed by a pacemaker as an R wave and therefore the pacemaker may therefore be inhibited – pacemakers might have to be switched to a VOO or DOO mode in order that they pace the chambers irrespective of what they sense for the duration of the procedure (this should be discussed with the surgeon to determine the kind of diathermy getting used and also the location of use with regard to the heart).
Insertion
Recent trends favor pacemaker and ICD surgery in EP laboratories as well as operating rooms [3]. Infection control is critical; operating room standards for air quality should be enforced. Pacemakers may be inserted in an EP laboratory by one skilled surgeon and one skilled circulating nurse. this is often satisfactory unless complications like angina, transient ischemic attack, patient disorientation, or lidocaine toxicity arise. Also, the presence of an anesthesiologist during pacemaker insertion is also warranted in patients who are likely to experience adverse intraoperative effects or are simply unstable as a results of dementia, delirium, myocardial ischemia, failure, anxiety, or ventricular tachycardia. Vancomycin reactions (Red Man syndrome), pacing-induced ventricular fibrillation, air embolism, and Stokes-Adams attacks may occur, albeit rarely, requiring assistance of a talented specialist. Intraoperative mortality can result from hemorrhage or myocardial infarction. Good clinical judgment about when an anesthesiologist is important is a vital issue, particularly within the elderly. If English isn't the patient's maternal language, a translator will be immensely helpful.
The type of monitoring employed during pacemaker implantation is crucial. Pacing artifacts that fail to capture might not be distinguishable from people who do solely on the premise of electrocardiogram (ECG) R-wave detection systems. Regular signaling from the monitor are often elicited in an asystolic patient despite subthreshold pacing. Oxygen-saturation monitors, on the opposite hand, signal only during blood flow. Additionally, palpation of temporal, facial, or artery pulses may be valuable for confirming the presence of an adequate pulse.
Venous access choices include the following: which side are going to be employed and whether or not a cutdown or percutaneous venipuncture are used. Cutdown approaches to the cephalic, external jugular, and internal jugular system are described. Subclavian venipuncture has recently been modified in an endeavor to reduce the frequency of subclavian crush. Subclavian puncture is related to a low incidence of pneumolhemothorax and major venous injury. Venous access is effectively impossible in a patient with superior vena cava syndrome or subclavian/innominate vein thrombosis (e.g., with chronic dialysis, mediastinal tracheostomy, or multiple pacemaker leads). Access from below is feasible, but the potential for thrombosis and embolism could be a concern. One useful approach described may be a right parasternal mediastinotomy. the right atrium is exposed for a Seldinger approach with small introducers through an atrial pursestring suture.
Early hospital discharge after pacemaker insertion is possible in patients who have an adequate escape rhythm. After monitoring and recovery from sedation, patients are ambulated and instructed in range of motion exercises for the shoulder. A chest radiograph is obtained to document lead position and rule out hemo/pneumothorax or pericardial enlargement. Lead displacement can be the results of technical error, physical resistance from uncooperative patients, and other factors. Because a small percentage of lead displacement is maybe unavoidable, patients who might suffer death or injury within the event of abrupt pacemaker failure should be observed within the hospital overnight on telemetry. Lead displacement in ambulatory patients has not occurred more frequently than in hospitalized patients.
Temporary Pacemaker
• Obtain venous access (usually femoral vein) with a sheath of larger diameter than the temporary wire to be used [4].
• Under X-ray screening, advance the pacing wire into the right atrium. The wire has a J-shaped distal contour which allows the tip to be directed by rotation of the proximal end of the wire.
• Direct the wire towards the apex of the right ventricle (this lies just medial to the apex of the cardiac silhouette on AP screening).
• If the wire doesn't move directly over the tricuspid valve it should be necessary to make a loop of wire within the atrium, usually achieved with the tip on the right lateral atrial border. Rotation and advancement of the wire may then result in prolapse through the tricuspid valve.
• As the wire enters the ventricle some ectopic activity is common and helps confirm a ventricular position.
• The wire can inadvertently enter the coronary sinus. Its orifice lies above the tricuspid valve. A wire within the coronary sinus appears more cranial on AP screening and on a lateral view moves posterior (rather than the desired anterior direction of a RV lead).
• Manipulate the wire in order that the tip curves downwards to the apex of the ventricle. In its final position the line of the wire should resemble the heel of a sock within the right atrium, with the toe within the apex of the right ventricle.
• Connect the lead to the pacing box and test the threshold for capture. Pace at a rate above the intrinsic cardiac rate while slowly turning down the box output (start at 3 V). The ECG monitor is observed to identify the output at which capture is lost. Increase again slowly to recapture.
Complications
Pacemaker infection appears as frank sepsis, intermittent fever with vegetations, or inflammation, purulence, and drainage at the pacemaker pocket [3]. Established infection in implanted prosthetic devices can be suppressed but rarely eliminated by antibiotics. Antibiotic suppression may lead to temporary resolution of drainage from a pacemaker or ICD (implantable cardioverter device) pocket, but a relapse usually occurs several months later. Negative cultures from pacemaker erosion may encourage the clinician to move the generator to a fresh, adjacent site. However, recurrent erosion usually results. Clinical resolution of recurrent device erosion in such individuals almost always requires removal of all hardware and insertion of a new device from a fresh site. Operator inexperience was recently shown to increase the incidence of erosions, infections, hematoma, and lead displacement early after pacemaker insertion.
The pulse width delivered to the ventricular lead should be a minimum of twice the threshold value. Adjusting generator output to a secure minimum can prolong pacemaker generator longevity and stop premature battery depletion. because of early instability of pacing thresholds, we make this adjustment 1 yr following insertion of latest pacemaker leads. Electrical component failures are rare. Over the past 10 yr, we've got seen three pacemaker and ICD generator failures, requiring urgent device replacement. New pacemakers and leads may contain design flaws which will not become apparent for several years.
Pacemaker dysfunction may be caused by mechanical defects in leads, lead displacement, or errors in connecting the lead to the generator. most typically, dysfunction represents scarring at the lead-myocardial interface, changes in myocardial properties as a results of tissue necrosis or drug effects, or a poor initial choice of lead position. Undersensing may be a failure to sense atrial or ventricular electro grams , manifested as an atrial or ventricular pacing artifact that should have been inhibited by a preceding (unsensed) beat. in a dualchamber pacemaker, undersensing might also appear as failure to pace the ventricle after an atrial P-wave. Such complications could also be resolved by programming increased generator sensitivity, but this could increase the risk of oversensing. The latitude for reprogramming is estimated by examining telemetered electrograms.
Oversensing is inappropriate pacemaker inhibition or triggering in unipolar systems that may result from detection of myopotentials (muscular activity). this will occur without compromise of lead integrity and should be correctable by reprogramming to reduce pacemaker sensitivity. Such problems in bipolar systems may indicate breakdown oflead insulation.
A deflection on the ventricular lead immediately after the atrial-pacing artifact could signal either a premature ventricular contraction or far-field sensing of an atrial depolarization. Many pacemakers deal with this ambiguity by pacing the ventricle at a really short (100 ms) AV delay. Observation of this phenomenon, called "safety pacing," indicates that the pacemaker is detecting a signal during the AV delay. Complexities of dual-chamber pacemaker programming involve blanking and refractory periods used to compensate either for crosstalk or for the onset of atrial fibrillation, or to prevent retrograde AV conduction from producing pacemaker-mediated tachycardia. Crosstalk is ameliorated by bipolar lead systems.
Pacing threshold is expected to increase over 7-14 d after lead insertion and so stabilize after about 6 wk. Exit block refers to a rising pacing threshold resulting from edema or scarring at the lead tip-myocardial interface. This phenomenon, which is believed to be related to inflammatory changes at the lead tip, is ameliorated by steroid eluting leads. Exit block is also corrected by programming increased amplitude or pulse width, but this shortens battery life. In unipolar systems, pacing of chest wall and/or diaphragm may result from high generator output.
Suspected lead fracture, whether resulting from insulation or conductor breaks, is commonly demonstrable by chest X -ray. Lead impedance of but 300 Q suggests an insulation break, whereas high lead impedance (more than 1000 Q) may suggest conductor problems. Telemetered electrograms, if available, should be monitored for noise while the patient hyperventilates, coughs, bends, and swings his arms. Pacemaker malfunction associated with body movement is a sign for lead replacement or repair. Dysfunctional leads should be capped. Lead removal is potentially traumatic and probably should be deferred unless infection or mechanical problems are an issue. The probability oflead fracture has, within the past, been increased by design errors, bipolar construction, certain forms of polyurethane insulation, and epicardial insertion. Technical factors may include tight ligatures applied to the lead without an anchoring sleeve, kinking, lead angulation, and "subclavian crush". An unusual form oflead fracture affects the Telectronics Accufix atrial screwin lead. A J -bend near the lead tip is maintained by a retention wire bonded to the lead body with polyurethane. The retention wire proved susceptible to fracture, followed by extrusion and cardiovascular injury.
Subclavian crush refers to entrapment of a pacemaker lead between the clavicle and flrst rib within the costoclavicular ligament. The lead is believed to be subjected to high levels of stress during body movement, with early lead failure as a result. This problem pertains to leads implanted by percutaneous puncture of the subclavian vein and should be avoided with cephalic cutdown.
Infections
Infections are severe complications of cardiac implantable electronic devices (CIED) [5]. for example, device-related endocarditis has an incidence of 10–23%, while infection of a pacemaker following implantation goes from 0.13% to 19.9%. Additionally, the incidence of ICD infection ranges from 0.7% to 1.2%. Cardiac device infective endocarditis encompasses a high mortality rate of 24.5–29% (with up to a year follow-up periods) and an 80–100% explantation rate. Moreover, 68–93% of infections are caused by Staphylococci and Gram-positive bacteria, whereas less than 18% of infections are due to Gram-negative bacteria. the fact that 15% of implantable cardiac device bacteria are culture negative must be considered.
Most of the infections related to pacemakers occur within the implantation pocket. Device infection may present some weeks later (a most typical scenario) or up to 1 year after the procedure. As a results of infected leads, vegetations can appear through all the lead path, which incorporates the tricuspid valve, the endocardium of the right atrium, and less frequently the right ventricle. Echocardiography is effective in visualizing and measuring vegetations together with evaluating the hemodynamic state of the heart. Transesophageal echocardiography must be performed in pacemaker bearers with suspected infective endocarditis.
Clinical presentation of systemic infections and endocarditis of the leads or valves commonly are fever, chills, positive blood cultures, and intracardiac vegetation. Pocket infection signs are swelling, redness, erosion, purulent discharge, chronic pocket pain, and alterations within the scar. Pocket fluid collection (visible with ultrasonography) and soft swelling may additionally present. during this case, recommendations are to take a blood culture, to perform sensitivity testing (if possible), and to initiate broad-spectrum antibiotics with focus on cutaneous flora (most commonly Staphylococcus aureus or Staphylococcus epidermidis) like vancomycin. Needle aspiration or incision of the pocket should be avoided, and also the patient must be referred to a middle experienced in treating infected devices to program removal and/or antibiotic therapy.
MRI
Most implanted cardiovascular devices are nonferromagnetic or only weakly ferromagnetic [6]. This includes most commonly used coronary stents, peripheral vascular stents, inferior vena cava (IVC) filters, prosthetic heart valves, cardiac closure devices, aortic stent grafts, and embolization coils. a statement on the security of scanning patients with cardiovascular devices was published by the American Heart Association, giving guidelines of the timing and safety of device scanning.
Pacemakers and implantable cardioverter defibrillators are strong relative contraindications to MRI (magnetic resonance imaging) scanning, and scanning of such patients should be performed only under specific conditions in centers with expertise in performing these studies. However, given the widespread use of pacemakers, concerns about not having the ability to perform MRI for even noncardiac indications have encouraged manufacturers to create multiple MRI safe pacemakers. the first such device is the Revo MRI SureScan system, which was approved by the FDA to be used in 2011 as an MRI-conditional device. And in 2015 the Evera MRI implantable cardioverter-defibrillator (ICD) became the first ICD approved by the FDA (US Food and Drug Administration) as an MRI-conditional device. The conditional designation still necessitates specific patient and MRI protocols to be followed to make sure safety. Nonetheless, these advances in pacemaker and ICD design have made it possible to perform both cardiac and noncardiac MRI imaging in patients with these selected devices. However, the artifacts that are generated by the pacemaker lead or the generator itself can affect interpretation of huge segments of the cardiac anatomy. Therefore the aim of a cardiac MRI study in a patient with a pacing or ICD system should be carefully considered before proceeding.
MRI safety requirements preclude the examination of patients possessing implanted electronic devices or some potentially mobile ferro-magnetic foreign bodies [7]. Even non-ferro-magnetic electrically conductive materials can become heated in a very strong magnetic field. Thus, some invasive monitoring devices used in the ICU (intensive care unit), like continuous cardiac output thermodilution pulmonary artery catheters and urinary catheter temperature probes, mustn't be brought into the MRI scanner. Completion of local safety screening requirements is mandatory for all patients and staff prior to entry into the MRI scanner room. Nevertheless, with appropriate use of modern MRI-compatible equipment, including invasive blood pressure monitoring and advanced mechanical ventilators, nigh the foremost unstable patients can be examined under appropriate medical supervision. providing a technique of safely and reliably measuring RBF (renal blood flow) during critical illness might now be available, it's pertinent to look at why these measurements are important and what mechanistic insights they may provide.
ICD
Implantable cardioverter de fi brillators (ICDs) include all the identical functions as a pacemaker with the addition of the ability to deliver rapid burst pacing or single or multiple electrical shocks to the heart in order to terminate a sensed ventricular tachyarrhythmia [8]. ICD generators have several differences from those of pacemakers and also are larger. ICD leads also are inherently different, including either a single or dual coils located along the length of the lead. The coils dictate the path the energy delivered will take during defibrillation (whether between the coil and also the generator or between coils). the explanation for using different potential defibrillation paths is that different shock polarities may have differing likelihood of defibrillation success.
Prior to defibrillation, however, most ICDs are programmed to deliver a minimum of one if not several rounds of ATP, or antitachycardia pacing. The goal of ATP is to terminate the ventricular arrhythmia without having to deliver a potentially painful ICD shock. ATP consists of delivering a prespecified number of paced beats at a rate a certain percentage faster than the sensed rate of the arrhythmia. Frequently, one or more rounds of ATP will terminate the tachycardia without need for a shock, and particularly with ventricular tachyarrhythmias at lower rates which can be hemodynamically tolerated, several rounds of ATP are going to be offered prior to delivering the first ICD shock.
Given the increased morbidity and mortality related to both appropriate and inappropriate ICD shocks, the goal of programming in ICDs is to limit the necessity for shocks by programming ATP while also trying to optimize the ability of the device to discriminate VT from SVT. Various programming options, including discriminators used to differentiate the 2 types of arrhythmia based on morphologic similarity of ventricular signals to those in sinus, the rapidity of onset of the arrhythmia, and therefore the regularity of the ventricular rate, is used to help avoid inappropriate shocks.
Conclusion
The purpose of installing pacemaker is to eliminate the symptoms and reduce the risks of possible heart failure. After some time has passed since the pacemaker was implanted, the patient is free to return to his usual way of life before the operation itself. After installing the pacemaker, it is important to avoid sudden and extensive movements with the arms and shoulders for the first month, especially on the side where it is installed. Patients can use a variety of electronic devices in their household, but it is important to determine if the devices are correct and isolated. For example, people with a built-in pacemaker can drive a car normally and use mobile devices, although it is recommended that the mobile device be kept away from the installation site. People who have pacemaker implanted live a normal life and many often forget to have it until it is time for regular tests to establish heart health.
