Heart block

Dmgs that mimic or inhibit the actions of neurotransmitters released from parasympathetic or sympathetic nerves innervating the heart may also be used to treat supraventricular bradyarrhythmias, heart block, and supraventricular tachyarrhythmias. Those used in the treatment of arrhythmias may be found in Table 1. 

Isoproterenol. Isoproterenol hydrochloride is an nonselective P-adrenoceptor agonist that is chemically related to NE. It mimics the effects of stimulation of the sympathetic innervation to the heart which are mediated by NE. It increases heart rate by increasing automaticity of the SA and AV nodes by increasing the rate of phase 4 diastoHc depolarization. It is used in the treatment of acute heart block and supraventricular bradyarrhythmias, although use of atropine is safer for bradyarrhythmias foUowing MI (86). 

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 PATIENT WITH HEART BLOCK. The patient receiving atropine for third-degree heart block is placed on a cardiac monitor during and after administration of the drug. The nurse watches the monitor for a change in pulse rate or rhythm. Tachycardia, other cardiac arrhythmias, or failure of the drug to increase the heart rate must be reported to the primary health care provider immediately because other dm or medical management may be necessary. 

The tricyclics can cause cardiac-related adverse reactions such as tachycardia and heart block. For this reason, the nurse gives these drugs with caution to the person with preexisting cardiac disease and to the elderly. 

Vigorito C, Russo P, Picotti GB, Chiariello M, Poto S, Marone G Cardiovascular effects of histamine infusion in man. J Cardiovasc Pharmacol 1983 5 531. Patterson LJ, Milne B Latex anaphylaxis causing heart block role of ranitidine. Can J Anaesth 1999 46 776. 

Complete Heart Block No PbTx Antibody Treatment (Lead VIO. 1 cm/mv. 25 mm/sec)... 

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... 

Labetalol hydrochloride 20-80 mg IV bolus every 10 minutes 5-10 minutes 3-6 hours Vomiting, scalp tingling, dizziness, bronchoconstriction, nausea, heart block, orthostatic hypotension Most hypertensive emergencies except acute heart failure... 

Esmolol hydrochloride 250-500 mcg/kg/minute IV bolus, then 50-100 mcg/kg/minute by infusion may repeat bolus after 5 minutes or increase infusion to 300 mcg/minute 1-2 minutes 10-30 minutes Hypotension, nausea, asthma, first-degree heart block, heart failure Aortic dissection, perioperative... 

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... 

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... 

In third-degree AV nodal blockade, or complete heart block, the heart rate is usually 30 to 40 bpm, resulting in symptoms. 

ECC first-degree heart block, right bundle-branch block, and arrhythmias... 

IV infusion dizziness, nausea, heart block, orthostatic hypotension... 

Adverse effects of /3-blockade include hypotension, heart failure, bradycardia, heart block, bronchospasm, altered glucose metabolism, fatigue, malaise, and depression. Abrupt withdrawal in patients with angina has been associated with increased severity and number of pain episodes and MI. Tapering of therapy over about 2 days should minimize the risk of withdrawal reactions if therapy is to be discontinued. 

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