Bradycardia block

In high concentrations it blocks calcium channels and, thus, exerts prominent negative inotropic effects. Its adverse effects include proarrhythmic effects, worsening of heart failure and (due to (3-adrenoceptor blockade) bradycardia and bronchospasm. 

Cardiac glycosides have a small ratio of toxic to therapeutic concentration. Possible adverse effects are nausea, vomiting, abdominal pain, diarrhoea, fatigue, headache, drowsiness, colour vision disturbances, sinus bradycardia, premature ventricular complexes, AV-block, bigeminy, atrial tachycardia with AV-Block, ventricular fibrillation. There are several mechanisms relevant for their toxic action (Table 2). 

These drags are contraindicated in patients with an allergy to the (3 blockers, in patients with sinus bradycardia, second- or third-degree heart block, heart failure, and those with asthma, emphysema, or hypotension. The drug are used cautiously in patients with diabetes, thyrotoxicosis, and peptic ulcer. 

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. 

Additive sympathomimetic effects may develop when decongestants are administered with other sympathomimetic drug s (see Chap. 22). Use of the nasal decongestants with the MAOIs may cause hypertensive crisis. Use of a decongestant with beta-adrenergic blocking dragp may cause hypertension or bradycardia. When ephedrine is administered with theophylline, the patient is at increased risk for theophylline toxicity. 

Labetalol 3-6 hour 5-10 minute 10-120 mg/hour Conduction block, heart failure, bradycardia, bronchospasm, exacerbate underlying pulmonary disease Rapid onset of action... 

Bradycardia (heart rate <60 bpm), systolic blood pressure <100 mmHg, severe left ventricular dysfunction with pulmonary edema, second- or third-degree heart block, PR interval >0.24 s, evidence of hypoperfusion, active asthma... 

MERIT-HL74 Bradycardia Heart block Latigue... 

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 randomized, controlled, clinical trials, calcium channel blockers were as effective as p-blockers at preventing ischemic symptoms. Calcium channel blockers are recommended as initial treatment in IHD when /3-blockers are contraindicated or not tolerated. In addition, CCBs may be used in combination with /3-blockers when initial treatment is unsuccessful. However, the combination of a (1-blocker with either verapamil or diltiazem should be used with extreme caution since all of these drugs decrease AV nodal conduction, increasing the risk for severe bradycardia or AV block when used together. If combination therapy is warranted, a long-acting dihydropyridine CCB is preferred. (3-Blockers will prevent reflex increases in sympathetic tone and heart rate with the use of calcium channel blockers with potent vasodilatory effects. 

Patients may also present with arrhythmias and therefore may have tachycardia, bradycardia, or heart block. 

The most serious side effects of P-blocker administration early in ACS are hypotension, bradycardia, and heart block. While initial, acute administration of P-blockers is not appropriate for patients who present with decompensated heart failure, initiation of P-blockers maybe attempted before hospital discharge in the majority of patients following treatment of acute heart failure. P-Blockers are continued indefinitely. 

As described in the previous section, calcium channel blockers should not be administered to most patients with ACS. Their role is a second-line treatment for patients with certain contraindications to P-blockers and those with continued ischemia despite P-blocker and nitrate therapy. Administration of either amlodipine, diltiazem, or verapamil is preferred.2 Agent selection is based on heart rate and left ventricular dysfunction (diltiazem and verapamil are contraindicated in patients with bradycardia, heart block, or systolic heart failure). Dosing and contraindications are described in Table 5-2. 

Diltiazem and Hypotension, bradycardia, heart block, BP and HR every shift during oral administration during... 

Adenosine Chest pain, flushing, shortness of breath, sinus bradycardia/AV block... 

Amiodarone IV Hypotension, sinus bradycardia Oral Blue-grey skin discoloration, photosensitivity, corneal microdeposits, pulmonary fibrosis, hepatotoxicity, sinus bradycardia, hypo- or hyperthyroidism, AV block... 

Diltiazem Hypotension, sinus bradycardia, heart failure exacerbation, AV block... 

Propranolol Hypotension, bradycardia, AV block, heart failure exacerbation3... 

Sotalol Sinus bradycardia, AV block, fatigue, torsades de pointes... 

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