QRS complex


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complex

 [kom´pleks]
1. the sum, combination, or collection of various things or related factors, like or unlike; e.g., a complex of symptoms (see syndrome).
2. a group of interrelated ideas, mainly unconscious, that have a common emotional tone and strongly influence a person's attitudes and behavior.
3. that portion of an electrocardiographic tracing which represents the systole of an atrium or ventricle.
AIDS-related complex (ARC) a complex of signs and symptoms occurring in HIV infection including fever, weight loss, prolonged diarrhea, minor opportunistic infections, lymphadenopathy, and changes in cells of the immune system.
antigen-antibody complex here the complex formed by the noncovalent binding of an antibody and antigen. Complexes of antibodies belonging to certain immunoglobulin classes may activate complement. Called also immune complex.
anti-inhibitor coagulant complex (AICC) a concentrated fraction from pooled human plasma, which includes various coagulation factors. It is administered intravenously as an antihemorrhagic in hemophilic patients with inhibitors to coagulation factor VIII.
atrial complex the P wave of the electrocardiogram, representing electrical activity of the atria. See also ventricular complex.
castration complex in psychoanalytic theory, unconscious thoughts and motives stemming from fear of loss of the genitals as punishment for forbidden sexual desires.
Electra complex libidinous fixation of a daughter toward her father. This term is rarely used, since oedipus complex is generally applied to both sexes.
factor IX complex a sterile, freeze-dried powder consisting of partially purified coagulation factor IX fraction, as well as concentrated factor II, VII, and X fractions, of venous plasma from healthy human donors. It is used in the prophylaxis and treatment of bleeding in patients with hemophilia B, replacement of factor VII in patients deficient in that factor, and treatment of anticoagulant-induced hemorrhage. Administered intravenously.
Ghon complex primary complex (def. 1).
Golgi complex golgi apparatus.
HLA complex the human major histocompatibility complex, which contains the hla antigens.
immune complex antigen-antibody complex.
inclusion complex one in which molecules of one type are enclosed within cavities in the crystalline lattice of another substance.
inferiority complex unconscious feelings of inadequacy, producing shyness or timidity or, as a compensation, exaggerated agressiveness and expression of superiority; based on Alfred Adler's concept that everyone is born with a feeling of inferiority stemming from real or imagined physical or psychological deficiency, with the manner in which the inferiority is handled determining behavior.
interpolated premature ventricular complex a premature ventricular complex that does not interfere with the conduction of the next sinus beat, i.e., it lacks the usual following compensatory pause.
major histocompatibility complex (MHC) the chromosomal region containing genes that control the histocompatibility antigens; in humans it controls the hla antigens.
membrane attack complex (MAC) C5b,6,7,8,9, the five-molecule complex that is the cytolytic agent of the complement system.
Oedipus complex see oedipus complex.
primary complex
1. the combination of a parenchymal pulmonary lesion (Ghon focus) and a corresponding lymph node focus, occurring in primary tuberculosis, usually in children. Similar lesions may also be associated with other mycobacterial infections and with fungal infections.
2. the primary cutaneous lesion at the site of infection in the skin, e.g., chancre in syphilis and tuberculous chancre.
QRS complex a group of waves seen on an electrocardiogram, representing ventricular depolarization. Called also QRS wave. It actually consists of three distinct waves created by the passage of the cardiac electrical impulse through the ventricles and occurs at the beginning of each ventricular contraction. In a normal surface electrocardiogram the R wave is the upward deflection; the first downward deflection represents a Q wave and the final downward deflection is the S wave. The Q and S waves may be extremely weak and sometimes are absent.

One abnormality of the QRS complex is increased voltage resulting from enlargement of heart muscle, which produces increased quantities of electric current. A low-voltage QRS complex may result from toxic conditions of the heart, most commonly from fluid in the pericardium. Pleural effusion and emphysema also can cause a decrease in the voltage of the QRS complex.
VATER complex an association of congenital anomalies consisting of vertebral defects, imperforate anus, tracheoesophageal fistula, and radial and renal dysplasia.
ventricular complex the Q, R, S, and T waves of the electrocardiogram, representing ventricular electrical activity. See also atrial complex.

QRS com·plex

portion of electrocardiogram corresponding to the depolarization of ventricular cardiac cells.

QRS complex

a series of waveforms on an electrocardiogram that represents both normal and abnormal depolarization of ventricular muscle cells. It is composed of Q, R, and S waves: a Q wave is the negative deflection before the first R wave, an R wave is any positive deflection, and an S wave is the negative deflection after an R wave. If there is no R wave, the totally negative complex is designated QS. A combination of uppercase and lowercase letters is used to describe the amplitude of each wave. Some variations of the QRS complex are qR, QR, qRs, rS, RS, and rSR′. Also called QRS wave.

QRS complex

R-wave Cardiac pacing The deflections on an EKG tracing produced by a ventricular depolarization

QRS com·plex

(kom'pleks)
An electrocardiographic complex consisting of the Q, R, and S waves, representing propagation of a wave of depolarization over the ventricles.

QRS complex

The part of the electrocardiograph tracing corresponding to the contractions of the main chambers of the heart (the ventricles). The Q wave is a short downwards deflection, the R wave a conspicuous upwards stroke and the S wave a return to below the level of the base-line.

QRS complex, QRS wave

a group of waves depicted on an electrocardiogram; it actually consists of three distinct waves created by the passage of the cardiac electrical impulse through the ventricles and occurs at the beginning of each contraction of the ventricles. In a normal electrocardiogram the R wave is the most prominent of the three; the Q and S waves may be extremely weak and sometimes are absent.
References in periodicals archive ?
Nonsurvivors: subjects who had a composite of cardiac death or new onset VT (primary endpoint); NYHA: New York Heart Association; LAD: left atrial diameter; LVESD: left ventricular end-systolic diameter; LVEF: left ventricular ejection fraction; PVC: premature ventricular contraction; VT: ventricular tachycardia; DUR: vector magnitude of the filtered QRS complex signal-averaged duration; IVET + : positive intraventricular electrical transients on SAECG; 24-h SDNN: 24-h standard deviation of normal RR intervals (see text for details).
widened or change in morphology of QRS complex from baseline.
4) The negative polarity of the QRS complex in II, III, and aVF leads is characteristic of the avian ECG and causes the MEA to be negative (approximately -90[degrees], cranial).
In a recently published study from our institution, we used the TDI-based longitudinal strain of papillary muscles, and we reported that 60 ms cut-off value of the papillary muscle dyssynchrony predicted the FMR volume >20 mL in DCM patients with narrow QRS complex (17).
The P wave, QRS complex, and T wave are recognizable deflections of the ECG tracing and indicate atrial depolarization, ventricular depolarization, and ventricular repolarization, respectively.
After the pause, the rate is slower, there are no P waves, and the QRS complex widens and changes morphology from Rs to QS with notching.
Kuck, "In a clinical setting, the primary way a physician diagnoses tachyarrhythmias is by analyzing a patient's QRS complex on an ECG.
Thus, withholding CRT treatment from a significant proportion of heart failure patients with a narrow QRS complex (< 120 ms) that have LV dyssynchrony could be unwise.
An electrocardiogram showed sinus P waves at a rate of 44 per minute and repeated sequences of a right ventricular escape complex that occurred nearly simultaneously with one of the sinus P waves, a conducted normal QRS complex with a P-R interval of 0.
The RethinQ study, which followed 172 patients for six months, was designed to determine whether CRT can help heart failure patients with a narrow QRS complex (the time required for the heart muscle to contract, as measured by electrocardiogram) and left ventricular mechanical dyssynchrony (when the heart's main pumping chambers, the ventricles, do not contract together efficiently).