First degree heart block

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... 

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

Ivabradine is used in the treatment of angina in patients in normal sinus rhythm. It acts on the sinus node resulting in a reduction of the heart rate. It is contraindicated in severe bradycardia (heart rate lower than 60 beats/ minute), cardiogenic shock, acute myocardial infarction, moderate-to-severe heart failure, immediately after a cerebrovascular accident, second and third-degree heart block and patients with unstable angina or a pacemaker. Side-effects include bradycardia, first-degree heart block, ventricular extrasystoles, headache, dizziness and visual disturbances, including blurred vision. 

First-degree heart block Exercise caution if the patient exhibits or develops first-degree heart block while taking procainamide dosage reduction is advised. If the block persists despite dosage reduction, evaluate the continuation of procainamide on the basis of current benefit vs risk of increased heart block. Predigitalization for atrial flutter or fibrillation Cardiovert or digitalize patients with atrial flutter or fibrillation prior to procainamide administration to avoid enhancement... 

Heart block If first-degree heart block develops, reduce dosage. If the block persists, drug continuation must depend upon the benefit compared with the risk of higher degrees of heart block. Development of second- or third-degree AV block or unifascicular, bifascicular, or trifascicular block requires discontinuation of therapy, unless ventricular rate is controlled by a ventricular pacemaker. 

Sinus bradycardia greater than first degree heart block cardiogenic shock congestive heart failure (CHF) unless secondary to a tachyarrhythmia treatable with -blockers overt cardiac failure hypersensitivity to -blocking agents. 

Bronchial asthma overt cardiac failure greater than first-degree heart block ... 

Early reports on imipramine noted that some patients developed first-degree heart block, as well as other bundle branch patterns, but it took almost 15 years to clarify that these conduction delays were the only adverse effects at therapeutic plasma concentrations. It is now well documented that increased PR, QRS, or QT intervals occur with all standard TCAs, at or slightly above their therapeutic plasma levels. 

Care should be taken in patients with a recent myocardial infarction who show evidence of impaired conduction (first-degree heart block, bundle-branch block, or prolongation of the QTC interval), since tricyclic antidepressants can theoretically add to the already increased risk of ventricular fibrillation in such patients (31). Reviews in earlier editions of Meyler s Side Effects of Drugs discussed these effects and gave practical guidelines on the use of tricyclic antidepressants in patients with heart disease (32). 

Two cases of light-headedness or fainting in patients taking olanzapine have been reported (80). Electrocardiograms showed first-degree heart block and AV conduction delay, which normalized after dosage reduction. 

The incidence of atrioventricular block has been reported in 600 consecutive patients who underwent stress myocardial perfusion imaging with adenosine (140 micrograms/kg/minute for 6 minutes), and of whom 43 had first-degree heart block before adenosine and 557 had a baseline PR interval less than 200 ms (Table 1) (31). The heart block in all cases was of short duration, was not associated with any specific symptoms, and in no case required specific treatment. The risk of atrioventricular block during adenosine infusion was not increased by the presence of other drugs that might have caused atrioventricular block (digitalis, beta-blockers, diltiazem, verapamil). 

Atrioventricular block was common (42%) first-degree, 14% second-degree, 17% and complete, 11%). However, first-degree heart block (that is prolongation of the PR interval) without higher degrees of atrioventricular nodal block can occur in the absence of digitalis intoxication. 

An 81-year-old woman with congestive heart failure and hypercalcemia secondary to squamous cell carcinoma of the bronchus developed first-degree heart block and symptomatic sinus pauses when her serum digoxin concentration was only 1.5 mg/ml (152). 

African children who received halofantrine (three doses of 8 mg/kg 6-hourly) for uncomplicated P. falciparum malaria had increases in both the PR interval and the QTc interval out of 42 children in the study, two children developed first-degree heart block and one child second-degree heart block the QT interval either increased by more than 125% of baseline value or by more than 0.44 seconds (an effect that persisted for at least 48 hours) (6). 

A 68-year-old man was given 0.5% bupivacaine 4 ml or spinal anesthesia, and 5 minutes later complained of nausea and developed hypotension, loss of consciousness, and a tonic-clonic seizure. He had first-degree heart block 4 minutes after subarachnoid injection, followed 1 minute later by third-degree heart block, and then asystole. He was successfully resuscitated. Proposed theories included a reflex bradycardia resulting from reduced venous return and/or unopposed... 

In a retrospective study of 85 patients with recurrent atrial fibrillation (mean left atrial size 46 mm, mean left ventricular ejection fraction 0.51), 69 of whom had structural heart disease, moricizine (mean dose 609 mg/day) was withdrawn because of unacceptable adverse effects in six patients frequent ventricular extra beats and short runs of non-sustained ventricular tachycardia n — 2) significant widening of the QRS complex (n — 1) first-degree heart block (n = 1) a significant rise in liver enzymes (n = 1) and a severe rash (n = 1) (4). Six patients developed transient adverse effects that resolved spontaneously without withdrawal brief self-limiting episodes of atrial flutter (n = 2) a small increase in blood pressure (n = 1) generalized weakness and tremor n = 2) and reduced appetite (n = 1). 

In chronic disease, patients present with cardiomyopathy and heart failure. Electrocardiograms are usually abnormal, demonstrating extrasystoles, first-degree heart block, right bundle-branch block, and other serious conduction disturbances. Degeneration... 

Acebutolol is indicated in the management of hypertension and premature ventricular contractions. It is contraindicated in hypersensitivity to beta-blockers persistently sever bradycardia greater than first-degree heart block congestive heart failure, unless secondary to tachyarrhythmia treatable with beta-blockers overt cardiac failure sinus bradycardia cardiogenic shock. The side effects reported for acebutolol include hypotension, bradycardia, CHF, cold extremities, heart block, insomnia, fatigue, dizziness. 

Frequent Anticholinergic effects hypotension O ss with nortriptyline) drowsiness weight gain tachycardia Occasional Mania psychosis tremor first-degree heart block other ECG abnormalities rash sweating confusion insomnia sexual disturbances, especially with clomipramine increase in dental caries gingivitis... 

In advanced heart failure, it is common to see abnormal electrical conduction. Heart failure patients can have first-degree heart block and/or intraventricular conduction delay. The intraventricular conduction delay is usually manifest as left bundle branch block. It has been estimated that one-third of patients with systolic heart failure have a QRS duration greater than 120 ms (3). 

These conduction disturbances typically worsen overall cardiac function. The AV delay seen with first degree heart block can lead to suboptimal contribution of atrial systole, less filling time for the LV, and worsened mitral regurgitation (4,5). The intraventricular conduction abnormality can lead to regional LV wall motion delay, which is termed LV dyssynchrony. In LBBB, the LV lateral wall typically depolarizes late and therefore, contracts late. This delayed contraction of the LV lateral wall occurs when the septum is already in its relaxation phase. On echo, it can be seen that the relaxed septum moves paradoxically away from the lateral wall late in systole. This is inefficient contraction since the septum and lateral walls are not moving in unison to... 

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