Cardiac conduction abnormalities

Extra-articular involvement may include rheumatoid nodules, vasculitis, pleural effusions, pulmonary fibrosis, ocular manifestations, pericarditis, cardiac conduction abnormalities, bone marrow suppression, and lym-phadenopathy. 

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. 

The Working Group on Status Epilepticus recommends that phenobar-bital be given after a BZ plus phenytoin has failed. Most practitioners agree that phenobarbital is the long-acting anticonvulsant of choice in patients with hypersensitivity to the hydantoins or in those with cardiac conduction abnormalities. 

Concomitant therapy Concomitant therapy with -blockers or digitalis is usually well tolerated, but the effects of coadministration cannot be predicted, especially in patients with left ventricular dysfunction or cardiac conduction abnormalities. 

Uses Rx prevent osteoporosis male female, Rx steroid-induced osteoporosis, Paget Dz Action -1- N1 abnormal bone resorption Dose Osteoporosis Rx 10 mg/d PO or 70 mg qwk Fosamax plus D 1 tab qwk Steroid-induced osteoporosis Rx 5 mg/d PO Prevention 5 mg/d PO or 35 mg qwk Paget Dz 40 mg/d PO Caution [C, ] Not OK if CrCl <35 mLAnin, w/ NSAID use Contra Esophageal anomalies, inability to sit/stand upright for 30 min, X Ca Disp Tabs, soln SE GI disturbances, esophageal irritation, HA, pain, jaw osteonecrosis (w/ dental procedures, chemo) Interactions -1- Absorption W7 antacids, Ca supls, Fe, food T risk of upper GI bleed W/ ASA NSAIDs EMS May cause cardiac conduction abnormalities d/t T Ca T risk of jaw fractures esp w/ dental procedures OD May cause hypocalcemia and adverse upper-GI effects milk or antacids can be given to bind alendronate... 

Ca, leg cramps EMS May cause cardiac conduction abnormalities d/t T monitor ECG not used to prevent osteoporosis osteosarcoma has been rqwrted in animals OD May cause NA, HA, and h5 percalcemia and associated cardiac conduction problems s5rmptomatic and supportive... 

Although b-blockers are considered the treatment of choice for akathisia, low doses of clonazepam, diazepam, or lorazepam may also reduce its severity ( 172, 389, 445, 447, 448, 449 and 450). These BZDs may be a useful alternative when a-blockers are contraindicated (e.g., in patients with asthma, insulin-dependent diabetes meilitus, cardiac conduction abnormalities) or as an adjunct when akathisia persists despite stepwise escalation of these agents ( 177). 

Some patients may experience hearing loss, which may accompany diabetes. Usually, type 2 diabetes is described in individuals with MELAS, although type 1 or insulin-dependent diabetes also may be observed. Palpitations and shortness of breath may be present in some patients with MELAS secondary to cardiac conduction abnormalities such as Wolff-Parkinson-White syndrome. Acute onset of gastrointestinal manifestations (e.g., acute onset of abdominal pain) may reflect pancreatitis, ischemic colitis, and intestinal obstruction. Numbness, tingling sensation, and pain in the extremities can be manifestations of peripheral neuropathy. Some patients may have the presentation of Leigh syndrome (i.e., subacute necrotizing encephalopathy). 

Medications such as P-blockers, calcium channel blockers, digoxin, and amiodarone can be used to control cardiac conduction abnormalities (arrhythmias), and a pacemaker may be inserted to combat heart failure. The general supportive care measures used in acute stroke syndromes also should be followed. Death in patients with MELAS is usually the result of cardiac failure, pulmonary embolus, or renal failure. 

Deaths have been described after venlafaxine overdose, but in combination with other agents and alcohol. However, there have been two fatal cases of overdosage in which venlafaxine was the only agent detected postmortem (30). It therefore appears that venlafaxine can occasionally prove fatal in overdosage, probably through cardiac conduction abnormalities and seizures (30,31). It is possible that poor metabolizers may be especially liable to develop toxic effects. 

Caution with calcium channel blockers because of risk of bradycardia and cardiac conduction abnormalities... 

Overdose, which may be absolute or relative (due to impaired renal excretion or in elderly patients who develop adverse effects at lower dosages), leads to severe hypotonia, mental confusion and somnolence, respiratory depression, and eventually apnea, bradycardia, cardiac conduction abnormalities, hypotension, and coma. Convulsions can occur and hypertension has been reported. It is possible that during recovery the picture may be complicated by an acute withdrawal syndrome, with agitation, psychosis, tremor and dystonic movements, convulsions, and hallucinations (SEDA-11, 126) (36 0). 

Nugent S, Katz MD, Little TE. Baclofen overdose with cardiac conduction abnormalities case report and review of the literature. J Toxicol Clin Toxicol 1986 24(4) 321-8. 

Buflomedil is generally considered to be innocuous at therapeutic dosages. Acute toxicity is due to accidental or intentional overdosage. Overdosage causes generalized seizures and cardiac conduction abnormalities, eventually leading to cardiac arrest (SEDA-21, 215). 

Pre-existing cardiac conduction abnormalities, including those induced by other drugs, are a definite risk. Due consideration should be given not only to the half-life of such drugs, but also to the tissue concentrations and total clearances of the agents involved. 

Continuous cardiac monitoring is recommended for patients with serious conduction abnormalities however, routine cardiac monitoring is considered unnecessary in patients without a history of cardiac conduction abnormalities (7). Further studies are needed to determine the risk in patients treated with paclitaxel with predisposing cardiac risk factors. 

In patients with colic, the most relevant clinical sign of hypokalemia is reduced intestinal motility (Geimari 1998, Schaer 1999). However, the association between h) okalemia and ileus in the horse remains undetermined. Other clinical signs include muscle weakness, lethargy and inability to concentrate urine (Schaer 1999). Cardiac conduction abnormalities are rare except in severe hypokalemia and in pre-existing cardiac dysfunction (Gennari 1998). The effect of potassium on acid-base status is small and need not be considered clinically (Corley Marr 1998). 

Serious ingestions require cardiac monitoring in an intensive-care setting. Hypotension may be resistant to dopamine and dobutamine. Norepinephrine can also be used. Bradycardia can be treated with atropine and a temporary pacemaker as needed. Digoxin-specific FAB antibody fragments have been used with some success for cardiac conduction abnormalities after a yew exposure. If no contraindication, lido-caine, amiodarone, or procainamide may be used for ventricular dysrhythmias. 

Large mtDNA deletions account for most cases of ocular myopathy and Pearson s marrow/pancreas syndrome. Ocular myopathy patients can exhibit a variety of clinical symptoms, from mild chronic progressive external ophthalmoplegia (CPEO) to Kearns-Sayre Syndrome (KSS). These diseases are characterized by an early onset of ophthalmoplegia, atypical retinitis pigmentosa, mitochondrial myopathy, and usually cerebellar syndrome and cardiac conduction abnormalities. More than 120 different mtDNA deletions have been identified from patients tissues. Partial duplications of mtDNA have been detected in ocular myopathy and Pearson s syndrome, however, duplications are much rarer than spontaneous deletions in patients with these conditions. Exactly how partial mtDNA duplications arise is unknown. 

The heart is sometimes affected by rheumatoid arthritis. Rheumatoid arthritis is associated with an increased risk of cardiovascular mortality. This risk appears to be higher in those with more active inflammation and is reduced with treatment, particularly with methotrexate. Pericarditis may occur, resulting in the accumulation of fluid. Although many patients show evidence of previous pericarditis at autopsy, the development of clinically evident pericarditis with tamponade is a rare complication. Cardiac conduction abnormalities and aortic valve incompetence, caused by aortic root dilatation, may occur. Myocarditis is a rare complication of rheumatoid arthritis. 

Mefloquine hydrochloride (lariam) is available for oral administration only. Tablets marketed in the U.S. contain 250 mg mefloquine hydrochloride, equivalent to 228 mg mefloquine base (this may vary in Canada and elsewhere). The dosing below is expressed in mg salt. Adults and children >45 kg body weight take 250 mg weekly starting 1-2 weeks before entering an endemic area and ending 4 weeks after leaving. Pediatric doses, taken by the same schedule, are 5 mg/kg for children up to 15 kg (may have to be prepared by a pharmacist) 62.5 mg (1/4 tablet) for 15-19 kg 125 mg (V2 tablet) for 20-30 kg 187.5 mg /k tablet) for 31 5 kg. Note Mefloquine is not recommended for children weighing <5 kg or individuals with a history of seizures, severe neuropsychiatric disturbances, sensitivity to quinoline antimalarials, or cardiac conduction abnormalities. 

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