Pacemakers risks

Clinical evaluation is underway to test transvenous electrodes. Transvenous leads permit pacemakers to be implanted under local anesthesia while the patient is awake, greatly reducing recovery time and risk. As of 1996, the generation of implantable defibrillators requires a thoracotomy, a surgical opening of the chest, in order to attach electrodes to the outside of the heart. Transvenous electrodes would allow cardiologists to perform pacemaker procedures without a hospital or the use of general anesthesia. 

Blockers are contraindicated in patients with severe bradycardia (heart rate less than 50 beats per minute) or AV conduction defects in the absence of a pacemaker. (3-Blockers should be used with particular caution in combination with other agents that depress AV conduction (e.g., digoxin, verapamil, and diltiazem) because of increased risk for bradycardia and heart block. Relative contraindications include asthma, bronchospastic disease, severe depression, and peripheral vascular disease. (3,-Selective blockers are preferred in patients with asthma or chronic obstructive pulmonary... 

In patients who have experienced VT and are at risk for sudden cardiac death, implantation of an implantable cardioverter-defibrillator (ICD) is the treatment of choice.44 An ICD is a device that provides internal electrical cardioversion of VT or defibril -lation of VF the ICD does not prevent the patient from developing the arrhythmia, but it reduces the risk that the patient will die of sudden cardiac death as a result of the arrhythmia. Whereas in the past ICD implantation required a thoracotomy, these devices now may be implanted transvenously, similarly to pacemakers, markedly reducing the complication rate. 

As well as the obvious risks, there can be less obvious risks too. Heart pacemakers can be disrupted by strong magnetic fields so this needs to be pointed out to anyone who enters the area in case they are reliant on one. Another risk is for people who have certain metal prosthetics (e.g., hip joints) - you wouldn t want them stuck to the side of the magnet, would you Another example that we have had is with metal breathing apparatus - someone was pulled back to the magnet when wearing it during a fire drill. 

Cardiostimulation. By stimulating Pi-receptors, hence activation of ade-nylatcyclase (Ad-cyclase) and cAMP production, catecholamines augment all heart functions, including systolic force (positive inotropism), velocity of shortening (p. clinotropism), sinoatrial rate (p. chronotropism), conduction velocity (p. dromotropism), and excitability (p. bathmotropism). In pacemaker fibers, diastolic depolarization is hastened, so that the firing threshold for the action potential is reached sooner (positive chronotropic effect, B). The cardiostim-ulant effect of p-sympathomimetics such as epinephrine is exploited in the treatment of cardiac arrest Use of p-sympathomimetics in heart failure carries the risk of cardiac arrhythmias. 

Heart block If first-degree heart block develops, reduce dosage. If the block persists, drug continuation must depend upon the benefit compared with the risk of higher degrees of heart block. Development of second- or third-degree AV block or unifascicular, bifascicular, or trifascicular block requires discontinuation of therapy, unless ventricular rate is controlled by a ventricular pacemaker. 

CRT is now recommended for patients with LVEF less than or equal to 35%, sinus rhythm, and NYHA functional class III or ambulatory class IV symptoms despite recommended, optimal medical therapy and who have cardiac dyssynchrony, which is currently defined as a QRS duration greater than 0.12 ms, unless contraindicated. To date, over 4,000 patients have been studied in randomized clinical trials of CRT. A recent evaluation of complications from those studies suggest a risk of implant mortality of 0.4%, failure to implant a functioning LV lead in 10%, lead malfunction or dislodgement in 8.5%, and pacemaker infection in 1.4% [123]. 

Saxon LA, Stevenson WG, Middlekauff HR, Stevenson LW. Increased risk of progressive hemodynamic deterioration in advanced heart failure patients requiring permanent pacemakers. Am. Heart J. 1993 125 1306-10. 

In general, a medical device is defined as follows a medical device is an implant and equipment to be used either to achieve disease diagnosis, medical treatment, or disease prevention for human and animals, or to influence the physical structure and function of human and animals. Medical devices for humans may also be classified based on whether and how long the device is in contact with tissue or cells and on the degree of disjunction induced by the device when in a disabling situation. The term covers various categories, such as scissors and tweezers, with small risk to human function, to central venous catheters, artificial dialysis (human kidney), and pacemakers, with high risk to human function. 

Rarely malignant arrhythmias during sexual activity may cause sudden death Risk is decreased by an implanted defibrillator or pacemaker Obstructive hypertrophic cardiomyopathies... 

Bradyarrhythmias (including asystole) and/or hypotension are frequent in CS, usually occur during balloon inflations and generally respond promptly to balloon deflation. Prevention is by adequate hydration, conservative balloon sizing, premedication with atropine and early ambulation. Although some advocate the routine prophylactic use of temporary transvenous pacemakers in CS (64,65), we consider the risks of this procedure to outweigh any potential benefit. In one series (n = I 14), a transvenous pacemaker was required in 9.6% (66), though in our experience this is needed far less frequently, Permanent pacemaker requirement is exceptionally rare, Occasionally, patients require short-term treatment... 

Medical devices are classified and regulated according to their degree of risk to the public. Devices that are life-supporting, life-sustaining, or implanted, such as pacemakers, must receive agency approval before they can be marketed. 

Cardiovascular Disease. Patients with systemic hypertension, arteriosclerosis, and other cardiovascular diseases may be at risk when high concentrations of topically administered adrenergic agonists such as phenylephrine are used. Repeated topical doses or soaked cotton pledgets placed in the conjunctival sac have been associated with adverse cardiovascular effects. Likewise, P-blockers should be avoided or used cautiously in patients with congestive heart disease, severe bradycardia, and high-grade atrioventricular block. Topical P-blockers, however, may be used safely in patients with cardiac pacemakers. 

Some patients are at risk of a form of arrhythmia called fibrillation, which is a completely uncoordinated, quivering, nonfunctional heartbeat. If not corrected quickly, fibrillation can cause death. Since 1985, pacemakers have been available to monitor the speed of the heart and deliver an appropriate electrical shock to the heart muscle if it begins to fibrillate. The device can deliver a low-level pacing shock, an intermediate shock, or a jolting, defibrillating shock if necessary. 

Titanium is so widely used that the risk of contact sensitivity to it must be very small. If a patient shows contact sensitivity to titanium, a replacement pacemaker should be completely encased in patch-tested non-allergenic material. 

Class III—Premarket Approval Devices that support or sustain life or present a significant risk of illness or injury fall under the Class-Ill category. Implants, such as pacemakers and silicone gel breast implants, are Class-Ill products, as are internal tissue adhesives, thermal ablation devices, synthetic ligaments and tendons, vacumn pumps, and prosthetic hips. Class-Ill accounts for about 10% of aU medical devices. 

The adverse effects associated with the use of verapamil include constipation, sinus node blockade, prolongation of the PR interval, AV dissociation, hypotension, and pulmonary congestion." The risks may outweigh the benefits in patients with (1) a markedly elevated pulmonary capillary wedge pressure or pulmonary artery occlusion pressure, (2) a history of paroxysmal nocturnal dyspnea or orthopnea, (3) sick sinus syndrome or significant AV nodal disease in the absence of a permanent pacemaker, (4) low systolic blood pressure, and (5) a substantial outflow gradient.Verapamil should be avoided inpatients with heart failure owing to systolic dysfunction. There is no evidence that either /3-blockade or verapamil protects the patient from sudden cardiac death. 

Conceptually, the potential complications of CRT-pacemaker or CRT-defibrillator implantation include the known complications of transvenous pacemaker or ICD implant (bleeding, infection, pneumothorax, vascular injury, cardiac perforation/tamponade, and cardiac decompensation from defibrillation testing) as well as the potential complications of LV lead implant (coronary venous dissection/perforation, contrast nephropathy, and perhaps elevated risk of infection or heart failure exacerbation due to prolonged procedure times). In addition, the passive fixation nature of LV leads raises the rates of post-procedure lead dislodgement. However, the rates of serious adverse events from the implantation procedure reported in the large clinical trials have been low. In MIRACLE, 2 patients (of 571) died as a result of the procedure. Correspondingly, 6% had a dissection or perforation of a coronary vein, but only 3 of those 35 patients required intervention and... 

Life-threatening hazard If a client was at risk of death due to the adverse reaction or if it is suspected that continued use of a product could cause death (e.g., pacemaker failure of an intravenous pump that could cause excessive drug dosing)... 

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