SM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition) defines insomnia as difficulty in initiating or maintaining sleep, or as non-restorative sleep for at least 1 month. The sleep disturbance is also associated with daytime fatigue or impaired daytime functioning. The multiple causes of insomnia and irritability in the heart failure syndrome can be loosely categorized as organic and psychologic.
Cheyne-Stokes respiration, an independent marker of increased mortality, is common even in mild-to-mod-erate heart failure. In sleep disorders such as obstructive sleep apnea, the repeated episodes of nocturnal desaturation and arousal from sleep lead to cognitive impairment. The combination of cognitive impairment and increased daytime somnolence is responsible for an increased risk of motor vehicle accidents. Cheyne-Stokes respiration in heart failure is caused by left ventricular dysfunction (circulatory delay), increased chemoresponsiveness (controller gain) to hypercapnia and hypoxia, reduced intrapulmonary stores of oxygen and carbon dioxide (under-damping), and an elevated apneic threshold. Transient periods of even mild nocturnal hypoxia increase the already elevated peripheral chemoreceptor response to carbon dioxide. The arousal stimulus in patients with Cheyne-Stokes respiration is the negative swing in intrathoracic pressure seen during periods of hyperpnea, rather than the mild degree of hypoxia associated with central apnea. The therapeutic conundrum is illustrated by Staniforth et al who found that although oxygen therapy stabilized sleep disordered breathing and reduced sympathetic activity, it improved neither symptoms nor cognitive function. Severe irritability may be an indication for neurologic referral to exclude cerebral dysfunction due to ischemia or other causes.
Majani et al found sleep disturbance in half their heart failure patients. It was associated with hospitalization and/or mood disturbance. Indeed, terminal insomnia (early waking) often signals the onset of depression. Chronic heart failure patients are at greater risk of mood disturbance than healthy subjects. Majani et al confirmed their vulnerability using two instruments, the Cognitive Behavioural Assessment 2.0 Battery and the Satisfaction Profile, revealing the high prevalence of sleep disturbance, financial difficulty, dysfunctional eating behavior, and sexual dysfunction.
Irritability may signal the onset of depression, a personality disturbance, or difficulty in adapting to the burden of a chronic disease, with the associated loss of independence in activities of daily living.
Neither insomnia nor irritability should be underestimated. Both are important symptoms. They are sufficiently debilitating and distressing to justify proactive intervention by the physician, with direct questioning followed by appropriate management, remembering that insomnia is a generic term, and not the only type of sleep disturbance likely to be encountered. Where quality of life is impaired, there should be no hesitation in referring patients to a psychologist or, in the more severe cases, to a psychiatrist. The physician must also remember that either symptom may also point to an underlying organic or psychologic cause which needs addressing in its own right.
How do you manage irritability and sleep disturbance in heart failure? Photo Gallery
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