Heart rhythm disturbances,

The same applies to pathologically-disturbed function. A simulated reduction in coronary blood flow (heart attack) would lead to reduced oxygen supply to the cells in the virtual heart, which would reduce efficiency of cardiac contraction and possibly give rise to heart rhythm disturbances. Ventricular pressure development would be compromised, as would the blood supply to all organs of the body, including the heart. All these implications can be studied in a virtual heart. 

The major clinical uses of atenolol include hypertension angina pectoris acute myocardial infarction (MI) heart rhythm disturbances and migraine prophylaxis. In hypertonia disease, various studies have addressed the efficacy of atenolol in... 

Vomiting, sedation, heart rhythm disturbances, dizziness, sweating, nausea, tremor... 

Sympfoms associafed wifh cifalopram overdose include vomiting, sedation, heart rhythm disturbances, dizziness, sweating, nausea, tremor, and rarely amnesia, confusion, coma, convulsions... 

Rarely lethal in monotherapy overdose vomiting, sedation, heart rhythm disturbances, dilated pupils, agitation fatalities have been reported in sertraline overdose combined with other drugs or alcohol... 

DOT CLASSIFICATION 8 Label Corrosive SAFETY PROFILE Poison by ingestion, inhalation, and intravenous routes. Questionable carcinogen with experimental tumorigenic data. Experimental reproductive effects. A corrosive. A skin and severe eye irritant. An allergen. Has been reported as causing irritation of mucous membranes and heart rhythm disturbances in humans. Violent reaction with water -(above 30°C), acetone + water, methanol, methanol + sodium hydrogen carbonate, 2-ethoxyethanol, dimethyl formamide, 3-butanone + sodium hydroxide + water, allyl alcohol + sodium hydroxide + water (at 28°C). When heated to decomposition it emits toxic fumes of CL and NOx. See also CHLORIDES. 

The list of research studies goes on and on, all with favorable results. We now know that the main fish oils, eicosapentanoic acid (EPA) and docohexanoic acid (DHA), work in a number of wonderful ways. These omega-3 fatty acids reduce the formation of blood clots and raise levels of the protective HDL cholesterol while dramatically lowering triglycerides. They prevent heart rhythm disturbances and they lower heart rates. Because heart rate is associated with the risk of sudden death, this association may at least partially explain the lower risk of sudden death among people who regularly eat fish. 

Heart rhythm disturbance leading to heart failure due to consequences of rhabdomyolysis and hypernatraemia (raised potassium concentration)... 

Benign familial hypercalduria, polyuria, polydipsia, loss of K and appetite, somnolence, heart-rhythm disturbances... 

The substances were studied in vivo in rats at a dose equivalent to 30 mg/kg of the pharmacon per os, in an experimental model of heart-rhythm disturbance induced by the intravenous administration of aconitine [28], The relative time (t) (compared with the control) until the onset of arrhythmia after aconitine administration served as an index of the antiarrhythmic activity. 

The major drawback of these models, however, is their lack of a clear reference between model components and constituent parts of the biological system (e.g. structures like ion channels, transporter proteins, receptors, etc.). These models, therefore, do not permit the simulation of patho-physiological detail, such as the series of events that follows a reduction in oxygen supply to the cardiac muscle and, ultimately, causes serious disturbances in heart rhythm. 

Clearly, cardiac function may not be addressed exclusively on the basis of describing the working mechanisms of single cells. Both normal and disturbed heart rhythms are based on a spreading wave of electrical excitation, the meaningful investigation of which requires conduction pathways of at least hundreds if not thousands of cells in length. 

Premature ventricular complexes (PVCs) are common ventricular rhythm disturbances that occur in patients with or without heart disease and may be elicited experimentally by abnormal automaticity, triggered activity, or reentrant mechanisms. 

Therapeutic uses. Because of their narrow therapeutic margin, these antiarrhythmics are only employed when rhythm disturbances are of such severity as to impair the pumping action of the heart, or when there is a threat of other compUcations. The choice of drug is empirical If the desired effect is not achieved, another drug is tried. Combinations of antiarrhythmics are not customary. Amiodarone is reserved for special cases. 

Propranolol has two separate and distinct effects. The first is a consequence of the drug s (3-blocking properties and the subsequent removal of adrenergic influences on the heart. The second is associated with its direct myocardial effects (membrane stabilization). The latter action, especially at high clinically employed doses, may account for its effectiveness against arrhythmias in which enhanced (3-receptor stimulation does not play a significant role in the genesis of the rhythm disturbance. 

Brief History. M.R. is a 48-year-old man with a history of coronary artery disease and cardiac rhythm disturbances. Specifically, he has experienced episodes of paroxysmal supraventricular tachycardia, with his heart rate often exceeding 180 beats per minute. He has been treated for several years with the nonspecific beta blocker propranolol (Inderal). Oral propranolol (60 mg/d) has successfully diminished his episodes of tachycardia. In an effort to improve his myocardial function and overall cardiovascular fitness, M.R. recently enrolled as an outpatient in a cardiac rehabilitation program. Under the supervision of a physical therapist, he attended cardiac training sessions three times each week. A typical session consisted of warm-up calisthenics, bicycle ergometry, and cool-down stretching activities. Each session lasted approximately 45 minutes. 

Inhalants make the heart extra sensitive to adrenaline, a hormone secreted in reaction to stresses. Adrenaline can trigger an irregular heartbeat, which disrupts the body s ability to ship oxygen-rich blood to the brain. Lastly, if an abuser is startled or sent into a fight-or-flight reaction, the body will release extra adrenaline. The extra-sensitivity can disturb the heart rhythm to the point of fatal cardiac arrest. 

In this section, caffeine is discussed only briefly and the focus is on other stimulants that produce psychiatric disorders. Caffeine can lead to a withdrawal syndrome characterized by lethargy, irritability, and headache, but withdrawal appears to occur in less than 3% of regular coffee drinkers. Moreover, the morbidity associated with caffeine overdose, which can include disturbing effects on sleep and heart rhythm, is much less than the morbidity associated with other stimulants. 

Q2 Symptoms of anxiety can include breathlessness, palpitations (increased awareness of the heart beat, or an irregular heart rhythm), dry mouth, difficulty in swallowing, flatulence, nausea, diarrhoea, tachycardia, dizziness, blurred vision, sleep disturbance, sweating, tension, irritability, restlessness, apprehension, depression, worry, fear. Some patients also report chest pain or chest constriction. 

Q8 Many of the symptoms of hypercalcaemia are non-specific. In excitable cells the membrane potential is stabilized (hyperpolarization) and the cells become less excitable fatigue, weakness, lethargy, confusion, anorexia, nausea and constipation are common. There are changes in the electrocardiogram (ECG), leading to heart block and other cardiac rhythm disturbances. A condition similar to diabetes insipidus also occurs with symptoms of polydipsia and polyuria. These symptoms are due to a reduction in the responsiveness of the renal tubules to antidiuretic hormone (ADH). 

This activity is responsibe for one of its major side effects - disturbing the heart rhythm. 

To correct problems of rhythm disturbance or SA node malfunction, cardiologists often use a pacemaker, an electrical device implanted in the shoulder or abdomen of the patierrt with a wire leadir to the heart. This mecharrical pacemaker generates the electrical signal which regulates the heart s functions. The rate of heartbeat, which is set when the pacemaker is implanted, can be changed if necessary without surgery. Modem... 

Despite certain severe side effects, the drug lev-odopa (1-dopa) is currently used as the most effective medication in the treatment of Parkinson disease. Some of the adverse side effects are disorders of the digestive system, hemorrhage, disturbances in heart rhythm, depression, confusion, possible psychotic reactions, and delirious episodes. The extent of these reactions appears to be dependent on the amount of medication used. In some patients the mask-like facial expression gives way to distorted facial expressions, and other unusual body movements may result from the use of the drug. 

In adults, atrioventricular dissociation was common and in children atrial rhythm disturbances (1). In volunteers, atropine in doses of 1.6 mg/70 kg/minute causes episodes of nodal rhythm with absent P waves on the electrocardiogram (2) the episodes occurred before the heart rate had increased under the influence of the drug. In healthy men being anesthetized for dental surgery a dose of only 0.4 mg atropine intravenously 5 minutes before induction caused reductions in mean arterial pressure, stroke volume, and total peripheral resistance (3). 

P-ARK An enzyme that phosphoylates the occupied form of a G-protein coupled receptor, e.g. the 6-adrenoceptor, leading to uncoupling of that receptor and desensitization. ARMI age-related memory impairment, arrhythmia (dysrhythmia) An abnormality of heart rhythm or rate of heartbeat, usually caused by disturbance of the electrical impulses and their conduction within the heart. They include ectopic beats (isolated irregular beats), tachycardias (too fast a heartbeat), bradycardias (too slow a heartbeat) and atrial flutter and ventricular fibrillation. Arthus reaction A severe local inflammatory response, a skin reaction characterized by erythema, oedema, necrosis, local haemorrhage. A type III hypersensitivity reaction. Arunlakshana and Schild plot See Schild plot, ascites fluid The fluid that accumulates in the peritoneal cavity during certain pathological conditions, aspiration The withdrawal of fluid or tissue from the body by suction. 

Adverse Effects. Digoxin can produce a variety of cardiac and noncardiac adverse effects, but it is usually well tolerated by most patients (Table 14-11). Noncardiac adverse effects frequently involve the central nervous system or gastrointestinal system but also may be nonspeciflc (e.g., fatigue or weakness). Cardiac manifestations include numerous different arrhythmias that are believed to be caused by multiple electrophysio logic effects (see Table 14-11). Cardiac arrhythmias may be the flrst evidence of toxicity in a patient (before any noncardiac symptoms occur). Rhythm disturbances are of particular concern because patients with chronic heart failure are aheady at increased risk for sudden cardiac death presumably owing... 

Disorders of the conduction system through the heart are known as arrhythmias (or dysrhythmias), because the inherent rhythm of the heart is disturbed. There are different kinds of arrhythmia depending on which part of the heart is affected. 

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