& u rosis (12). Furthermore, the extent of cardiac dysfunction has been shown to be related to the severity of cardiac autonomic neuropathy, rather than to age, sex, duration or control of diabetes, microvascular complications, or plasma norepi-nephrine levels (26).

Cardiac autonomic dysfunction in patients with diabetes has also been linked to the incidence of lethal arrhythmia and sudden cardiac death. In asymptomatic diabetic patients, the presence of cardiac autonomic dysfunction appears to be a better predictor of major cardiac events than myocardial ischemia itself. The risk of events due to cardiac autonomic dysfunction appears to be independent of documented myocardial ischemia, although it is higher when associated with myocardial ischemia (27).

Cardiac autonomic dysfunction is a common, albeit less well recognized, consequence of diabetes on the cardiovascular system. This type of neuropathy is clinically perceived to be far less ominous when compared to other deleterious effects of diabetes on the heart, but is very closely intertwined within the manifestations of diabetic heart disease. In this context, it is important to note that patients with diabetes afflicted with autonomic neuropathy exhibit decreased survival and an increased risk of sudden death. Clinically, cardiac autonomic neuropathy may be apparent by the relatively fixed and rapid heart rate that barely responds to physiological stimuli, such as the Valsalva maneuver, carotid sinus pressure, standing, and tilting, and to the administration of drugs such as atropine or beta-blockers. The most notable manifestation of cardiac autonomic dysfunction is the impaired hemodynamic response to exercise. During exercise, the physiological augmentation in heart rate and systolic blood pressure are blunted in patients with cardiac autonomic dysfunction related to diabetes. In these patients, it is the severity of cardiac autonomic neuropathy that correlates with the maximal increase in heart rate, as opposed to the patient's age, duration of diabetes, or the presence and severity of microvascular disease. The diagnosis of cardiac auto-nomic dysfunction can be made when two or more of the following criteria are present:

1. Resting Heart Rate: Defined as a resting heart rate of 100 beats per minute or more after 15 min of rest in a supine position (in the absence of other causes).

2. Beat-to-Beat Variability: Defined as a lack of beat-to-beat variability of less than 10 beats per minute, determined as the difference between minimum and maximum heart rate on a resting electrocardiogram, obtained during normal inspiration and expiration with the patient breathing at least at 16 times per minute.

3. R-R Interval Ratio During a Valsalva Maneuver: Defined as the ratio Ja of the longest electrocardiographic R-R interval to the shortest R-R J

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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