digoxin and Acidosis

The electrical stability of the heart is more sensitive to the extracellular than to the intracellular potassium concentration. During exercise, extracellular potassium varies rapidly. Catecholamines also modulate the plasma potassium concentration. Hypokalaemia of any cause can precipitate arrhythmias. Ischaemic myocardium loses potassium into the extracellular space within seconds and the cell becomes depolarized. The rise of the extracellular potassium ion concentration accounts for many of the early electrophysiological changes. Abrupt changes of plasma potassium concentration in normal myocardium and a high potassium concentration in ischaemic myocardium can set up electrical forces which initiate arrhythmias. The same phenomenon can account for changes on the electrocardiogram early after the cessation of an exercise test in a patient with ischaemic heart disease. Accumulation of potassium between cells in response to an increase of heart rate is a possible mechanism for false positive exercise tests and Syndrome X.

Topics: Acidosis; Action Potentials; Angioplasty, Balloon; Animals; Catecholamines; Coronary Disease; Digoxin; Diuretics; Exercise Test; False Positive Reactions; Heart; Heart Rate; Humans; Hyperkalemia; Hypokalemia; Myocardium; Physical Exertion; Potassium; Syndrome

Topics: Acid-Base Equilibrium; Acidosis; Angiocardiography; Blood Gas Analysis; Blood Pressure; Bradycardia; Cardiac Catheterization; Cardiac Output; Child; Child, Preschool; Cineangiography; Cyanosis; Digoxin; Diuretics; Dyspnea; Electrocardiography; Heart Auscultation; Heart Block; Heart Defects, Congenital; Heart Failure; Heart Rate; Humans; Infant; Infant, Newborn; Oxygen Inhalation Therapy; Pulse; Referral and Consultation; Tachycardia; Vectorcardiography

A recent study has shown in the conscious dog that hypoxia associated with respiratory acidosis could increase the in vivo distribution of digoxin in the myocardium. The aim of the present study was to evaluate in vitro the effects of hypoxia and (or) hypercapnic acidosis on the digoxin uptake. For this purpose, rat myocardium was incubated for 180 min with radiolabelled [3H]digoxin. The uptake of digoxin which was expressed in nanograms of digoxin bound per 100 mg of myocardium was decreased by hypoxia and increased by hypercapnic acidosis. The association of hypoxia and hypercapnic acidosis had no effect on the digoxin uptake, suggesting that in vitro hypoxia acts in an opposite way to hypercapnia.

Topics: Acidosis; Animals; Biological Transport; Digoxin; Hypercapnia; Hypoxia; In Vitro Techniques; Kinetics; Male; Myocardium; Rats; Rats, Inbred Strains

Topics: Acidosis; Acidosis, Renal Tubular; Amiloride; Animals; Chlorides; Digoxin; Dogs; Electrolytes; Humans; Hypokalemia; Lithium; Syndrome; Tromethamine

A diagram based on in-vivo relationships between arterial hydrogen ion activity (H+) and carbon dioxide tension (PCO2) in primary abnormalities of acid base homeostasis is presented. It is designed to facilitate the interpretation of pH data by including the 95% confidence limits described in patients with simple metabolic and respiratory acid base disorders. These bands have been formulated from observation of simple acid base abnormalities and indicate the appropriate respiratory or renal compensatory response to the primary pH defect. A plot which falls outside these limits therefore indicates the presence of a mixed acid base disorder. The diagram presents a physiological approach to clinical disorders of pH regulation demonstrating maintenance of intra-cellular fluid homeostasis during primary extracellular fluid disturbances. Diagnostic and therapeutic advantages are further illustrated and discussed in six case reports.

Topics: Acid-Base Imbalance; Acidosis; Adolescent; Adult; Aged; Alkalosis; Alkalosis, Respiratory; Dehydration; Diabetic Ketoacidosis; Digoxin; Female; Humans; Hydrogen-Ion Concentration; Insulin; Male; Middle Aged; Sodium Chloride

Topics: Acidosis; Adult; Aged; Digoxin; Female; Furosemide; Heart Failure; Humans; Lactates; Male; Middle Aged; Renal Dialysis

Topics: Acidosis; Body Temperature; Cardiac Catheterization; Child; Cholesterol; Digoxin; Electrocardiography; Follow-Up Studies; Heart Auscultation; Heart Defects, Congenital; Humans; Hypertension; Infant; Pulse

Topics: Acidosis; Atrial Fibrillation; Bundle-Branch Block; Calcium; Colon, Sigmoid; Diagnosis, Differential; Digoxin; Electrocardiography; Female; Humans; Hyperkalemia; Hypocalcemia; Hypokalemia; Infant; Potassium; Tachycardia; Urinary Diversion; Water-Electrolyte Balance

Topics: Acidosis; Alkalosis; Anti-Bacterial Agents; Blood Transfusion; Body Temperature; Digoxin; Diuretics; Drainage; Glucose; Heart Arrest; Heart Defects, Congenital; Humans; Hypoglycemia; Hypoproteinemia; Infant, Newborn; Intubation, Intratracheal; Isoproterenol; Parenteral Nutrition; Positive-Pressure Respiration; Postoperative Care; Serum Albumin; Thrombocytopenia; Water-Electrolyte Balance

Topics: Acidosis; Angiocardiography; Cardiac Catheterization; Cineangiography; Diet Therapy; Digoxin; Diuretics; Electrocardiography; Heart Auscultation; Heart Defects, Congenital; Heart Diseases; Heart Failure; Humans; Infant, Newborn; Infant, Newborn, Diseases; Isoproterenol; Radiography, Thoracic; Respiration, Artificial

Topics: Acidosis; Digitalis Glycosides; Digoxin; Electric Countershock; Electrocardiography; Female; Heart Block; Humans; Hypokalemia; Infant, Newborn; Infant, Newborn, Diseases; Male; Tachycardia, Paroxysmal

Topics: Acidosis; Bicarbonates; Blood Pressure; Cardiac Output; Digoxin; Fructose; Humans; Hypoxia; Myocardial Infarction; Oxygen; Plasma Substitutes; Shock; Tromethamine