Sinus bradycardia treatment

Compare and contrast appropriate nonpharmacologic and pharmacologic treatment options for sinus bradycardia and AV nodal blockade. 

Design individualized drug therapy treatment plans for patients with (1) sinus bradycardia (2) AV nodal blockade (3) AF (4) PSVT (5) VPDs (6) VT (including torsades de pointes) and (7) VF. 

Many individuals, particularly those who partake in regular vigorous exercise, have heart rates less than 60 bpm. For those individuals, sinus bradycardia is normal and healthy, and does not require evaluation or treatment. However, some individuals develop symptomatic sinus node dysfunction. In the absence of correctable underlying causes, idiopathic sinus node dysfunction is referred to as sick sinus syndrome,12 and occurs with greater frequency with advancing age. The prevalence of sick sinus syndrome is approximately 1 in 600 individuals over the age of 65 years.12... 

Treatment of sinus bradycardia is only necessary in patients who become symptomatic. If the patient is taking any med-ication(s) that may cause sinus bradycardia, the drug(s) should be discontinued whenever possible. If the patient remains in sinus bradycardia after discontinuation of the drug(s) and after five half-lives of the drug(s) have elapsed, then the drugs(s) can usually be excluded as the etiology of the arrhythmia. In certain circumstances, however, discontinuation of the medication(s) may be undesirable, even if it may be the cause of symptomatic sinus bradycardia. For example, if the patient has a history of myocardial infarction or HF, discontinuation of a (3-blocker is undesirable, because (3-blockers have been shown to reduce mortality and prolong life in patients with those diseases, and the benefits of therapy with... 

Acute treatment of patients with second- or third-degree AV nodal blockade consists primarily of administration of atropine, which maybe administered in the same doses as recommended for management of sinus bradycardia. In patients with hemodynamically unstable or severely symptomatic AV nodal blockade that is unresponsive to atropine and in whom temporary or transvenous pacing is not available or is ineffective, epinephrine (2 to 10 mcg/minute, titrate to response) and/or dopamine (2 to 10 mcg/kg/minute) maybe administered.14... 

Sinus node disease andAVbiock The drug may cause severe sinus bradycardia or sinoatrial block in patients with preexisting sinus node disease and may cause advanced or complete heart block in patients with preexisting incomplete AV block. Consider inserting a pacemaker before treatment with digoxin. 

Inappropriate sinus bradycardia, sinoatrial block, and bradycardia-tachycardia syndrome (bradycardia followed by supraventricular tachyarrhythmias such as atrial fibrillation) are included in this syndrome. Treatment of sick sinus syndrome is generally based upon the patients symptoms. In general, bradycardia... 

Atropine can be used in the differential diagnosis of S-A node dysfunction. If sinus bradycardia is due to extracardiac causes, atropine can generally elicit a tachy-cardic response, whereas it cannot elicit tachycardia if the bradycardia results from intrinsic causes. Under certain conditions, atropine may be useful in the treatment of acute myocardial infarction. Bradycardia frequently occurs after acute myocardial infarction, especially in the first few hours, and this probably results from excessive vagal tone. The increased tone and bradycardia... 

Vomiting is common in patients with digitalis overdose. Hyperkalemia may be caused by acute digitalis overdose or severe poisoning, whereas hypokalemia may be present in patients as a result of long-term diuretic treatment. (Digitalis does not cause hypokalemia.) A variety of cardiac rhythm disturbances may occur, including sinus bradycardia, AV block, atrial tachycardia with block, accelerated junctional rhythm, premature ventricular beats, bidirectional ventricular tachycardia, and other ventricular arrhythmias. 

A 14-year-old boy received an intravenous dose of methylprednisolone 30 mg/kg for progressive glomerulonephritis. After 5 hours, his heart rate had fallen to 50/minute and an electrocardiogram showed sinus bradycardia. His heart rate then fell to 40/minutes and a temporary transvenous pacemaker was inserted and methylprednisolone was withdrawn. His heart rate increased to 80/minutes over 3 days. After a further 3 days, he was treated with oral methylprednisolone 60 mg/m2/day and his heart rate fell to 40/minutes in 5 days. Oral methylprednisolone was stopped on day 8 of treatment and his heart rate normalized. 

Neuroleptics are the drugs of choice in the treatment of tic disorders but they should only be considered in situations where the life of the child is seriously affected and when behavioural treatments have failed. Of the classical neuroleptics which have been used, haloperidol and pimozide have shown success but so far there have been no adequately controlled trials of any neuroleptic to objectively validate their efficacy. It would appear that only low doses of haloperidol are necessary (2-3mg/day) to obtain a significant reduction in tic frequency. It would seem reasonable to consider the use of the atypical antipsychotics for these disorders but, to date, there is no evidence of their efficacy in children. Recently there have been studies in which clonidine was used in the effective treatment of motor tics. The side effects are similar to those seen in the adult and include sedation, headache, irritability and sinus bradycardia. 

A 32-year-old woman took 800 mg of citalopram, 20 times her usual daily dose, in a suicide attempt. On admission to hospital she had a sinus bradycardia (41/ minute) but the electrocardiogram was otherwise normal, with a QT interval of 430 ms. Treatment with atropine failed to increase her heart rate and she had hypotension and syncope. A temporary pacemaker was inserted and was required for the next 6 days before it could be safely removed. 

A patient who took an overdose of trazodone (3 g) had sinus bradycardia (57 beats/minute) and a prolonged QTC interval (60 msec). The abnormal QTC interval gradually normalized over the next 3 days with supportive hospital treatment. 

A 39-year-old man had recurrent episodes of sinus tachycardia at 115/minute, with no other abnormalities. He was taking methadone 120 mg/day for opioid dependency and doxepin 100 mg/day for anxiety, and was given metoprolol 50 mg/day. During the next few weeks he had episodes of recurrent syncope with sinus bradycardia (47/minute) and prolongation of the QT interval (542 ms). The QT interval and heart rate normalized after withdrawal of all treatment. 

Symptomatic sinus bradycardia is a possible adverse effect of treatment with donepezil in Alzheimer s disease (51). 

An 84-year-old patient with hypertensive cardiomyopathy developed bradycardia, fainting, and left-sided heart failure 3 weeks after starting treatment with donepezil. When donepezil was withdrawn, the sinus bradycardia disappeared 24-hour electrocardiography showed no signs of sinus node disease, and no episodes of this type recurred during the next 6 months. 

Acute sinus bradycardia requires treatment if it is symptomatic e.g. where there is hypotension or escape rhythms extreme bradycardia may allow a ventricular focus to take over and lead to ventricular tachycardia. The foot of the bed should be raised to assist venous return and atropine should be given i.v. Chronic symptomatic bradycardia is an indication for the insertion of a permanent pacemaker. 

Amiodarone and carvedilol have been used in combination in 109 patients with severe heart failure and left ventricular ejection fractions of 0.25 (16). They were given amiodarone 1000 mg/week plus carvedilol titrated to a target dose of 50 mg/day. A dual-chamber pacemaker was inserted and programmed in back-up mode at a basal rate of 40. Significantly more patients were in sinus rhythm after 1 year, and in 47 patients who were studied for at least 1 year the resting heart rate fell from 90 to 59. Ventricular extra beats were suppressed from 1 to 0.1/day and the number of bouts of tachycardia over 167 per minute was reduced from 1.2 to 0.3 episodes per patient per 3 months. The left ventricular ejection fraction increased from 0.26 to 0.39 and New York Heart Association Classification improved from 3.2 to 1.8. The probability of sudden death was significantly reduced by amiodarone plus carvedilol compared with 154 patients treated with amiodarone alone and even more so compared with 283 patients who received no treatment at all. However, the study was not randomized, and this vitiates the results. The main adverse effect was s)mptomatic bradycardia, which occurred in seven patients two of those developed atrioventricular block and four had sinoatrial block and/or sinus bradycardia one patient developed slow atrial fibrillation. 

Prolongation of the QT interval is a recognized effect of 4-aminoquinolines. In 20 adult Cameroonian patients with non-severe falciparum malaria treated with amodiaquine (total dose 30 mg/kg or 35 mg/kg over 3 days) there was asymptomatic sinus bradycardia (n = 16) and prolongation of the PQ, QRS, and QT intervals at the time of maximum cumulative concentration of drug (day 2 of treatment) (1). 

Lunde P. Ventricular fibrillation after intravenous atropine for treatment of sinus bradycardia. Acta Med Scand 1976 199(5) 369-71. 

Cardiac dysrhythmias in digitalis overdose should be treated only if they are life-threatening. Phenytoin is probably the treatment of choice for ventricular tachydysrhyth-mias, but lidocaine or a beta-adrenoceptor antagonist, such as propranolol, are options. After an overdose of 300 tablets of digoxin (plasma digoxin concentration 50 ng/ml), recurrent ventricular fibrillation was successfully treated with bretylium tosylate (191). Sinus bradycardia may respond to atropine. 

O Cayley AC, Macpherson A, Wedgwood J. Sinus bradycardia following treatment with hydergine for cerebrovascular insufficiency. BMJ 1975 4(5993) 384-5. 

Five patients with acute accidental poisoning with V. album rapidly developed nausea, vomiting, abdominal pain, hypotension, and bradycardia (26). In four cases the electrocardiogram showed sinus bradycardia and in one there was complete atrioventricular block with an ectopic atrial bradycardia and an intermittent idioventricular rhythm. Symptomatic treatment and/or atropine led to recovery within a few hours. 

Sinus bradycardia was seen in 18% of patients taking mefloquine (SEDA-12, 693) (14), occurring some 4-7 days after administration the bradycardia was asymptomatic and lasted about 3-4 days. Transient sinus arrhythmia was also reported, without a need for treatment (SEDA-12, 808). Asymptomatic dysrhythmias were also recorded in a dosage comparison trial (SEDA-16, 308). 

About 4 hours after a 65-year-old man with Parkinson s disease took talipexole hydrochloride 0.8 mg, he acutely developed sleepiness, delusion, akinesia, and faintness associated with hypotension and sinus bradycardia. A similar episode occurred when he took talipexole hydrochloride 1.2 mg/day in combination with co-careldopa (levodopa 200 mg/day plus carbidopa 20 mg/day). These symptoms persisted for 12 hours and abated gradually without any specific treatment. 

Atropine is used in the management of sinus bradycardia with hemodynamic instability and in the treatment of peptic ulcer disease, irritable bowel syndrome, urinary incontinence, and organophos-phate and carbamate poisoning. It is also present in ophthalmic preparations to induce mydriasis and cyclopegia. Atropine is often administered preope-ratively to decrease secretions. 

In addition to drugs in these classes, others may be used for certain arrhythmias. Digoxin may be used for treatment of atrial fibrillation, adrenaline for asystolic cardiac arrest, atropine for sinus bradycardia, methacholine (rarely) for supraventricular tachycardia, magnesium salts for ventricular arrhythmias, and calcium salts for ventricular arrhythmia due to hyperkalaemia. 

An 86-year-old man who had been reeeiving captopril 25 mg twice daily and bendroflumethiazide 25 mg daily [sic] for hypertension, underwent a transurethral resection of his prostate under spinal anaesthesia using 3 to 3.5 mL of heavy bupivacaine 0.5%. At the end of surgery, he was returned to the supine position and suddenly developed a severe sinus bradycardia (35 bpm), his arterial blood pressure fell to 65/35 nunHg and he became unrousable. Treatment with head-down tilt, oxygen and 1.2 mg of atropine produced rapid improvement in cardiovascular and cerebral function. A further hypotensive episode (without bradycardia) occurred approximately one hour later, which responded rapidly to 4 mg of methoxamine. ... 

A 48-year-old man sprayed an unknown amount of lidocaine on to his penis before sexual activity and developed chest tightness and bradycardia for 2 days [55 ]. Cardiac enzymes were normal and an electrocardiogram showed sinus bradycardia without ST segment changes. The symptoms resolved after several hours of observation without any treatment. 

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