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. 

Hypercalcemia, (weakness, headache, somnolence, nausea, cardiac rhythm disturbance), hypercalciuria... 

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. 

The surface electrocardiogram (ECG) is the cornerstone of diagnosis for cardiac rhythm disturbances. 

Patients with acute stroke should be monitored intensely for the development of neurologic worsening, complications, and adverse effects from treatments. The most common reasons for clinical deterioration in stroke patients are (1) extension of the original lesion in the brain (2) development of cerebral edema and raised intracranial pressure (3) hypertensive emergency (4) infection (e.g., urinary and respiratory tract) (5) venous thromboembolism (6) electrolyte abnormalities and rhythm disturbances and (7) recurrent stroke. The approach to monitoring stroke patients is summarized in Table 13-3. 

The Petco2 falls rapidly over the course of a few breaths. With hyperventilation, the fall would be slower. Any condition that acutely reduces cardiac output may be the cause, including cardiac arrest, pulmonary embolism or acute rhythm disturbances. If the Pco2 falls instantly to zero, then the cause is disconnection, auto-calibration or equipment error. 

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. 

Monitoring - Laboratory test monitoring for liver abnormalities is appropriate. Rapid IV administration Rapid IV administration of cimetidine has been followed by rare instances of cardiac arrhythmias and hypotension. Bradycardia, tachycardia, and premature ventricular beats in association with rapid administration of IV ranitidine may occur rarely, usually in patients predisposed to cardiac rhythm disturbances. 

Now try this one for yourself - another patient with a rhythm disturbance, but this time a cardiac, not a cerebral, arrhythmia. 

Atrial fibrillation (AF) is one of the most common rhythm disturbances, and is characterized by the absence of discrete P wave and an irregular ventricular rhythm. Fibrillatory waves are either fine or... 

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. 

Cardiac arrhythmias are a common problem in clinical practice, occurring in up to 25% of patients treated with digitalis, 50% of anesthetized patients, and over 80% of patients with acute myocardial infarction. Arrhythmias may require treatment because rhythms that are too rapid, too slow, or asynchronous can reduce cardiac output. Some arrhythmias can precipitate more serious or even lethal rhythm disturbances for example, early premature ventricular depolarizations can precipitate ventricular fibrillation. In such patients, antiarrhythmic drugs may be lifesaving. On the other hand, the hazards of antiarrhythmic drugs—and in particular the fact that they can precipitate lethal arrhythmias in some patients—has led to a reevaluation of their relative risks and benefits. In general, treatment of asymptomatic or minimally symptomatic arrhythmias should be avoided for this reason. 

Vomiting is common in patients with digitalis overdose. Hyperkalemia may be caused by acute digitalis overdose or severe poisoning, whereas hypokalemia may be present in patients as a result of long-term diuretic treatment. (Digitalis does not cause hypokalemia.) A variety of cardiac rhythm disturbances may occur, including sinus bradycardia, AV block, atrial tachycardia with block, accelerated junctional rhythm, premature ventricular beats, bidirectional ventricular tachycardia, and other ventricular arrhythmias. 

Insomnia secondary to a general medical condition, especially with pain- or sleep-disordered breathing Circadian rhythm disturbance Periodic limb movement disorder Restless legs syndrome... 

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. 

The primary sleep disorders found in elderly that may lead to sleep disturbances are (1) circadian rhythm disturbances (CRD) (2) sleep disordered breathing (SDB) (3) insomnia and (4) restless legs syndrome and periodic limb movement disorder. 

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... 

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). 

Potassium (K+) and calcium (Ca2+) levels in blood are affected by renal failure. High K+ leads to muscle weakness and may cause cardiac rhythm disturbance. The low blood Ca2+ leads to defective mineralization of bones (osteomalacia)... 

A 66-year-old woman with mitral regurgitation and atrial fibrillation developed hypokalemia and a variety of rhythm disturbances at dosages of 40 mg or more per day. 

Two reviews of the cardiac effects of psychotropic drugs briefly mentioned lithium and dysrhythmias, with a focus on sinus node dysfunction (122,123), reports of which, as manifested by bradycardia, sinoatrial block, and sinus arrest, continue to accumulate in association with both toxic (124) and therapeutic (125,126) serum lithium concentrations. The rhythm disturbance normalized in some cases when lithium was stopped (124,126), persisted despite discontinuation... 

In a multicenter, randomized, double-blind comparison of diazepam (0.15 mg/kg followed by phenytoin 18 mg/kg), lorazepam (0.1 mg/kg), phenobarbital (15 mg/kg), and phenytoin (18 mg/kg) in 518 patients with generalized convulsive status epilepticus, lorazepam was more effective than phenytoin and at least as effective as phenobarbital or diazepam plus phenytoin (1). Drug-related adverse effects did not differ significantly among the treatments and included hypoventilation (up to 17%), hypotension (up to 59%), and cardiac rhythm disturbances (up to 9%). 

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

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