Sinoatrial blocks

The hydantoins are contraindicated in patients widi known hypersensitivity to die drug s. Phenytoin is contraindicated in patients widi sinus bradycardia, sinoatrial block, second and diird degree AV block, and Adams-Stokes syndrome it also is contraindicated during pregnancy (ediotoin and phenytoin are Pregnancy Category D) and lactation. Ediotoin is contraindicated in patients widi hepatic abnormalities. 

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... 

Propafenone causes sinus node slowing that could lead to sinoatrial block. It may lengthen the sinus node recovery time with minimal effects on sinus cycle length. 

Contraindications Hydantoin hypersensitivity, seizures due to hypoglycemia, Adam-Stokes syndrome, second- and third-degree heart block, sinoatrial block, sinus bradycardia... 

A very uncommon adverse effect involves sinus node dysfunction (extreme bradycardia, sinus arrest, sinoatrial block), which can be associated with syncopal episodes, perhaps due to hypothyroidism (119,120). In such cases, lithium must either be withdrawn or continued in the presence of a pacemaker. At therapeutic concentrations, other cardiac conduction disturbances have been reported, sometimes in conjunction with hypercalcemia (121), but are uncommon. 

Two reviews of the cardiac effects of psychotropic drugs briefly mentioned lithium and dysrhythmias, with a focus on sinus node dysfunction (122,123), reports of which, as manifested by bradycardia, sinoatrial block, and sinus arrest, continue to accumulate in association with both toxic (124) and therapeutic (125,126) serum lithium concentrations. The rhythm disturbance normalized in some cases when lithium was stopped (124,126), persisted despite discontinuation... 

A 70-year-old man developed lithium intoxication after a transient ischemic attack (174). He had a bradycardia (35-40/minute) and episodes of sinoatrial block. The clinical presentation was suggestive of a stroke. 

BETA-BLOCKERS DILTIAZEM t hypotensive and bradycardic effects cases of severe bradycardia and AV block when both drugs are administered concurrently in the presence of pre-existing heart failure or conduction abnormalities Additive effects on conduction diltiazem causes bradycardia, sinoatrial block and AV block. Also, diltiazem inhibits CYP1A2-mediated metabolism of propanolol Monitor PR, BP and ECG at least weekly until stable. Warn patients to report symptoms of hypotension (light-headedness, dizziness on standing, etc.)... 

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. 

ViUani GQ, del Giudice S, Arruzzoli S, Dieci G. Blocco seno-atriale dopo somministrazione orale di nifedipina. Descrizione di un caso. [Sinoatrial block after oral administration of nifedipine. Description of a case.] Minerva Cardioangiol 1985 33(9) 557-9. 

Three cases of carbamazepine-induced Stokes-Adams attacks caused by intermittent total atrioventricular block, sinoatrial block with functional escape rhythm, and intermittent asystole have been described it was suggested that cardiac conduction should be assessed if syncope or changes in seizure tjrpe occur in patients taking carbamazepine (5). 

Following the publication of a report of heart block (4), further cases (junctional bradycardia, sinoatrial block) have been reported (5). 

Boujnah MR, Jaafari A, Boukhris B, Boussabah I, Thameur M. Bloc sino-auriculaire induit par le diltiazem aux doses therapeutiques. A propos de trois observations. [Sinoatrial block induced by therapeutic doses of diltiazem. Report of 3 cases.] Tunis Med 2000 78(12) 735-7. 

Conduction disturbances are common with propafenone and can result in sinus bradycardia, sinoatrial block, sinus arrest, any degree of atrioventricular block, and right or left bundle-branch block (SEDA-10,151) (SEDA-15,179). 

An unusual dysrhythmia has been attributed to propranolol alternating sinus rhythm with intermittent sinoatrial block. The authors suggested that this was... 

Ozturk M, Demiroglu C. Alternating sinus rhythm and intermittent sinoatrial block induced by propranolol. Eur Heart J 1984 5(ll) 890-5. 

Quinidine has also been incriminated in cases of sinoatrial block and sinus arrest, but it was not clearly established that quinidine was responsible (9,10). The anticholinergic effects of quinidine can increase the risk of dysrhythmias (11). 

During repeated administration cardiovascular adverse effects are relatively uncommon. Increasing heart failure (14,15), worsening dysrhythmias (15,16), pericarditis (15,17,18), and sinus arrest with sinoatrial block (19) have all been reported. Tocainide can worsen ventricular tachycardia (20). 

Gould LA, Betzu R, Vacek T, Muller R, Pradeep V, Downs L. Sinoatrial block due to tocainide. Am Heart J 1989 118(4) 851-3. 

Do not use in sinus bradycardia, sinoatrial block, second- and third-degree AV block, or in patients with Adams-Stokes syndrome. 

Inoue H, Takayanagi K, Ueda K, Mifune J, Ohkawa S, Sugiura M. Three cases of sinoatrial block induced by anticonvulsants. Jpn Heart J 1978 19(4) 544-51. 

A 17-year-old boy took propafenone 3 g and had a sudden cardiac arrest with h5fpotension, left ventricular failure, bradycardia, sinoatrial block, and an atrioventricular junctional and ventricular tachycardia. He was treated with temporary cardiac pacing, catecholamines, and sodium bicarbonate, and the toxicity resolved within 4 hours [66 ]. 

Cardiovascular A woman taking losartan 25 mg/day and carbamazepine was admitted to hospital with head trauma secondary to syncope her heart rate was 30/minute and her serum potassium concentration 6.7 mmol/1 [53 ]. It was suspected that the hyperkalemia was associated with losartan, leading to third-degree sinoatrial block or complete sinus arrest. 

Distinguishing nonconducted premature atrial contractions from sinoatrial block... 

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