Macropsia is a neurological condition affecting human visual perception, in which objects within an affected section of the visual field appear larger than normal, causing the person to feel smaller than they actually are. Macropsia, along with its opposite condition, micropsia, can be categorized under dysmetropsia. Macropsia is related to other conditions dealing with visual perception, such as aniseikonia and Alice in Wonderland Syndrome (AIWS, also known as Todds syndrome). Macropsia has a wide range of causes, from prescription and illicit drugs, to migraines and (rarely) complex partial epilepsy, and to different retinal conditions, such as epiretinal membrane. Physiologically, retinal macropsia results from the compression of cones in the eye. It is the compression of receptor distribution that results in greater stimulation and thus a larger perceived image of an object. Signs and symptoms
The most obvious symptom of macropsia is the presence of exceptionally enlarged objects throughout the visual field. For example, a young girl might see her sisters books as the same size as her sister. Stemming from this symptom, someone with macropsia may feel undersized in relation to his or her surrounding environment. Patients with macropsia have also noted the cessation of auditory function prior to the onset of visual hallucination, indicating possible seizure either before or after the hallucination. A buzzing sound in the ears has also been reported immediately before macropsia development. Some patients claim that symptoms may be eased if an attempt is made to physically touch the object which appears enormous in size.
Atrial flutter, is caused by a re-entry rhythm in the atria, with a regular atrial rate often of about 300 beats per minute. On the ECG this appears as a line of "sawtooth" waves preceding the QRS complex. The AV node will not usually conduct 300 beats per minute so the P:QRS ratio is usually 2:1 or 4:1 pattern, (though rarely 3:1, and sometimes 1:1 where class IC antiarrhythmic drug are in use). Because the ratio of P to QRS is usually consistent, A-flutter is often regular in comparison to its irregular counterpart, atrial fibrillation. Atrial flutter is also not necessarily a tachycardia by definition unless the AV node permits a ventricular response greater than 100 beats per minute. AV nodal reentrant tachycardia (AVNRT) involves a reentry circuit forming next to, or within, the AV node. The circuit most often involves two tiny pathways one faster than the other. Because the node is immediately between the atria and ventricle, the re-entry circuit often stimulates both, appearing as a backward (retrograde) conducted P-wave buried within or occurring just after the regular, narrow QRS complexes. Atrioventricular reciprocating tachycardia (AVRT), also results from a reentry circuit, although one physically much larger than AVNRT. One portion of the circuit is usually the AV node, and the other, an abnormal accessory pathway (muscular connection) from the atria to the ventricle.