QRST complex

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QRST complex

Etymology: L, complexus
a series of waveforms on an electrocardiogram, consisting of the QRS complex, the S-T segment, and the T wave. It represents depolarization and repolarization of the ventriclular muscle cells.


(kom'pleks?) [L. complexus, woven together]
1. Intricate.
2. Of a complicated nature.
3. A group of interrelated biological entities.
4. An atrial or ventricular systole as it appears on an electrocardiographic tracing.
5. All the ideas, feelings, and sensations connected with a subject.
6. A subconscious idea (or group of ideas) that has become associated with a repressed wish or emotional experience and that may influence behavior, although the person may not realize the connection with the repressed thoughts or actions.
7. In Freudian theory, a grouping of ideas with an emotional background. These may be harmless, and the individual may be fully aware of them, e.g., an artist sees every object with a view to a possible picture and is said to have established a complex for art. Often, however, the complex is aroused by some painful emotional reaction such as fright or excessive grief that, instead of being allowed a natural outlet, becomes unconsciously repressed and later manifests itself in some abnormality of mind or behavior. According to Freud, the best method of determining the complex is through psychoanalysis. See: Electra complex; Jocasta complex; Oedipus complex
8. An anatomical or intracellular structure.

AIDS-dementia complex

Abbreviation: ADC
Encephalopathy caused by direct infection of brain tissue by HIV. This condition affects patients with severe immunosuppression more often than those whose immune function is stronger. Central nervous system HIV infection affects as many as 15% of AIDS patients, but in 1997 its incidence decreased to approx. 30% of its previous occurrence because of the effectiveness of highly active antiretroviral therapy (HAART). Central nervous system HIV infections in children tend to be more pronounced than those in adults.


The exact cause of AIDS dementia is unknown, but current theories suggest that it results from HIV infection of macrophages in the brain (microglia) and the destructive release of cytokines that disrupt neurotransmitter function.


AIDS dementia is characterized by slow, progressive memory loss, decreased ability to concentrate, a general slowing of cognitive processes, and mood disorders. Motor dysfunction may also be present, including ataxia, bowel and bladder incontinence, and seizures. Higher levels of HIV RNA in the cerebrospinal fluid (CSF viral load) are correlated with increased problems.


Treatment options may include highly active antiretroviral therapies. Since their introduction the incidence of AIDS-dementia complex has decreased.

Patient care

The patient's mental status and level of consciousness must be assessed and documented. Clear documentation is essential to track a patient's changes over time. Orientation to person, place, and time; thought processes (cognition); verbal communication skills; and memory losses can be determined through simple conversations that reveal the patient's ability to recall normal details of the day and previous teaching. Particular attention is paid to patients' abilities to comply with their complex medication regimen; inability to do so requires another person to assume responsibility for this task. The patient's affect and mood; the presence of agitated, restless, or lethargic behavior; and the extent to which clothing is clean and appropriate for the weather may reveal progressing dementia when compared with previously documented mental status assessments.

Interventions are based on clear communication. As patients develop dementia, they may become frightened, and a consistently gentle approach with positive feedback is essential. Clocks, calendars, and memory aids help the patient become reoriented. Step-by-step written instructions should be given to augment verbal instructions. Caregivers need to learn how to reorient the patient, how to recognize and treat hallucinations, how to create a safe environment, how to ensure that basic hygiene needs are met, and how to document medication schedules and intake because patients may forget to eat or drink adequately.

Synonym: HIV-associated dementia See: AIDS

AIDS-related complex

Abbreviation: ARC
The symptomatic stage of infection with human immunodeficiency virus (HIV) before the onset of AIDS. Its clinical signs include fatigue, intermittent fevers, weight loss greater than 10%, chronic or persistent intermittent diarrhea, night sweats, diminished delayed hypersensitivity (skin test) response to common allergens, presence of HIV antibodies in blood, and decreased CD4+ T-lymphocyte count.

amygdaloid complex


anti-inhibitor coagulant complex


castration complex

A morbid fear of being castrated.

Eisenmenger complex

See: Eisenmenger syndrome

Ghon complex

See: Ghon complex

HLA complex

Major histocompatibility complex.

immune complex


inferiority complex

The condition of having low self-esteem. It is a 20th-century term stemming from Adlerian therapy.

inferior olivary complex

Inferior olive.

major histocompatibility complex

Abbreviation: MHC
Synonym: HLA complex See: histocompatibility locus antigen

membrane attack complex

The combination of complement factors C5 through C9 that directly attack and kill the cell membranes of microorganisms during the terminal attack phase of the complement cascade.
See: complement; inflammation

Mycobacterium avium complex

Abbreviation: MAC, MAI
An atypical mycobacterium that causes systemic bacterial infection in patients with advanced immunosuppression, esp. those with AIDS. It occasionally causes lung infections in patients with chronic obstructive lung disease. Synonym: Mycobacterium avium-intracellulare complex




Multiple antimicrobial agents, given at the same time and for long courses, are required to treat MAC. Combination therapy may include a macrolide with drugs such as rifabutin, ethambutol, ciprofloxacin, amikacin, and/or clofazimine.

Mycobacterium avium-intracellulare complex

Mycobacterium avium complex.

nodal premature complex

Abbreviation: NPC
Ectopic cardiac beat originating in the atrioventricular node.

nuclear pore complex

A collection of membrane-associated proteins that regulate the passage of large molecules between the cytoplasm and the cell nucleus.

oculomotor complex

A group of interrelated nuclei found near the midline in the rostral midbrain. They include the oculomotor nucleus and the Edinger-Westphal nucleus, and they innervate somatic muscles, e.g., inferior rectus and levator palpebrae muscles, and visceral muscles (preganglionic parasympathetic axons to the ciliary ganglia) via the oculomotor nerve (CN III).

olivary complex

Olive (2).

osteomeatal complex

The middle turbinate and the middle meatus of the nose.

QRS complex


QRST complex

Q-T interval.

superiority complex


superior olivary complex

Superior olive.

symptom complex


tuberous sclerosis complex

Tuberous sclerosis.