Bradycardia, AV block

Cardiac conduction IV verapamil slows AV nodal conduction and SA nodes it rarely produces second- or third-degree AV block, bradycardia, and in extreme cases, asystole. This is more likely to occur in patients with sick sinus syndrome. 

Bundle-branch block, AV block, bradycardia, hypertension Serious Reactions... 

The major toxicities are extensions of their therapeutic effects. Frequent or severe adverse effects include dizziness, headache, edema, constipation (especially verapamil), atrioventricular (AV) block, bradycardia, heart failure, and lupus-like rash with... 

Contraindicated with thioridazines because of risk of AV block, bradycardia, and hypotension... 

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). 

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. 

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. 

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... 

Propafenone Dizziness, fatigue, bronchospasm, headache, taste disturbances, nausea, vomiting, bradycardia or AV block, aggravation of underlying HF, conduction disturbances, or ventricular arrhylhmias... 

Amiodarone Tremor, ataxia, pareslfresia, insomnia, corneal microdeposits, optic neuropathy/neuritis, nausea, vomiting, anorexia, constipation, TdP (<1%), bradycardia or AV block (IV and oral use), pulmonary fibrosis, liver function test abnormalities, hepatitis, hypothyroidism, hyperthyroidism, photosensitivity, bluegray skin discoloration, hypotension (IV use), phlebitis (IV use)... 

Diltiazem and verapamil can cause cardiac conduction abnormalities such as bradycardia, AV block, and heart failure. Both can cause anorexia, nausea, peripheral edema, and hypotension. Verapamil causes constipation in about 7% of patients. 

Ipratropium is used in bradycardia and AV-block, respectively, to raise heart rate and to facilitate cardiac impulse conduction. As a quaternary substance, it does not penetrate into the brain, which greatly reduces the risk of OIS disturbances (see below). Relatively high oral doses are required because of an inefficient intestinal absorptioa... 

Indications. Verapamil is used as an antiarrhythmic drug in supraventricular tachyarrhythmias. In atrial flutter or fibrillation, it is effective in reducing ventricular rate by virtue of inhibiting AV-conduction. Verapamil is also employed in the prophylaxis of angina pectoris attacks (p. 308) and the treatment of hypertension (p. 312). Adverse effects Because of verapamil s effects on the sinus node, a drop in blood pressure fails to evoke a reflex tachycardia Heart rate hardly changes bradycardia may even develop. AV-block and myocardial insufficiency can occur. Patients frequently complain of constipation. 

Signs of intoxication are (1) cardiac arrhythmias, which under certain circumstances are life-threatening, e.g., sinus bradycardia, AV-block, ventricular extrasystoles, ventricular fibrillation (ECG) (2) CNS disturbances — altered color vision (xanthopsia), agitation, confusion, nightmares, hallucinations (3) gastrointestinal — anorexia, nausea, vomiting, diarrhea (4) renal — loss of electrolytes and water, which must be differentiated from mobilization of accumulated edema fluid that occurs with therapeutic dosage. 

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. 

Uncontrolled CHF cardiogenic shock sinoatrial, AV and intraventricular disorders of impulse generation or conduction (eg, sick sinus node syndrome, AV block) in the absence of an artificial pacemaker bradycardia marked hypotension bronchospastic disorders manifest electrolyte imbalance hypersensitivity to the drug. 

Oral Severe sinus-node dysfunction, causing marked sinus bradycardia second-and third-degree AV block when episodes of bradycardia have caused syncope (except when used in conjunction with a pacemaker). 

Parenteral Marked sinus bradycardia second- and third-degree AV block unless a functioning pacemaker is available cardiogenic shock. 

Parenfera/- The most important treatment-emergent adverse effects were hypotension, asystole/cardiac arrest/electromechanical dissociation (EMD), cardiogenic shock, CFIF, bradycardia, liver function test abnormalities, VT, and AV block. The most common adverse effects leading to discontinuation of IV therapy were hypotension, asystole/cardiac arrest/EMD, VT, and cardiogenic shock. Adverse reactions occurring in at least 3% of patients include nausea. 

Oral verapamil - Oral verapamil may lead to first-degree AV block and transient bradycardia, sometimes accompanied by nodal escape rhythms. 

Hypertrophic cardiomyopathy (IHSS) Serious adverse effects were seen in 120 patients with IHSS (especially with pulmonary artery wedge pressure more than 20 mm Hg and left ventricular outflow obstruction) who received oral verapamil at doses up to 720 mg/day. Sinus bradycardia occurred in 11%, second-degree AV block in 4% and sinus arrest in 2%. 

Patients with decompensated cardiac failure requiring the use of IV inotropic therapy (such patients should first be weaned from IV therapy before initiating carvedilol) bronchial asthma (see Warninas) or related bronchospastic conditions second- or third-degree AV block sick sinus syndrome or severe bradycardia (unless a permanent pacemaker is in place) cardiogenic shock clinically manifest hepatic impairment hypersensitivity to the drug. 

Cardiovascular conditions - Cholinesterase inhibitors have vagotonic effects on the sinoatrial and atrioventricular nodes, leading to bradycardia and AV block. These actions may be particularly important to patients with supraventricular cardiac conduction disorders or to patients taking other drugs concomitantly that significantly slow heart rate. Consider all patients to be at risk for adverse effects on cardiac conduction. 

Phenytoin Because of its effect on ventricular automaticity, do not use phenytoin in sinus bradycardia, sino-atrial block, second- and third-degree AV block, or in patients with Adams-Stokes syndrome. 

Toxicity Toxicity is characterized by an exaggeration of parasympathomimetic effects which may include the following Headache visual disturbance lacrimation sweating respiratory distress Gl spasm nausea vomiting diarrhea AV block tachycardia bradycardia hypotension hypertension shock mental confusion cardiac arrhythmia tremors. 

Bronchial asthma, a history of bronchial asthma, or severe chronic obstructive pulmonary disease sinus bradycardia second- and third-degree AV block overt cardiac failure cardiogenic shock hypersensitivity to any component of the products. 

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