Pulsus bigeminus
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Pulsus bigeminus is a cardiovascular phenomenon characterized by groups of two heartbeats close together followed by a longer pause. The second pulse is weaker than the first. Look for a pattern of what appears to be a relatively normal
QRS complex The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the ri ...
es, each followed by a smaller, abnormal one. The smaller beat is palpated as either a missing or an extra beat, and on EKG resembles a PVC. These PVCs appearing every other beat are also called extrasystoles. This phenomenon can be a sign of
hypertrophic obstructive cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This r ...
or of many other types of heart disease (see list below). Other causes include digitalis toxicity, induction of anesthesia, placement of surgical instrumentation into the thorax or as a benign, temporary phenomenon. In Pulsus Bigeminus not all of the conducted electrical activity will elicit sufficient ventricular contraction to produce a palpable pulse. This is important for two reasons. One, an ECG may give a ventricular contraction rate that does not correspond to the palpated pulse rate. Secondly, because not all beats are being conducted, patients may present with symptoms of low output heart failure, e.g. Dizziness, shortness of breath or hypotension, even with a normal ECG.


Cause

Causes Include: # Electrolyte imbalance e.g. Hypo or
hyperkalemia Hyperkalemia is an elevated level of potassium (K+) in the blood. Normal potassium levels are between 3.5 and 5.0mmol/L (3.5 and 5.0mEq/L) with levels above 5.5mmol/L defined as hyperkalemia. Typically hyperkalemia does not cause symptoms. Occasi ...
# Hypothyroidism # Betablocker therapy # Digoxin #
Myocardial Infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...
# Destruction or degeneration of the
cardiac conduction system The cardiac conduction system (CCS) (also called the electrical conduction system of the heart) transmits the signals generated by the sinoatrial node – the heart's pacemaker, to cause the heart muscle to contract, and pump blood through the ...
or
heart muscle cells Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle th ...
# Infection A doctor can discriminate pulsus bigeminus from
pulsus alternans Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis. Pathophysiology One explanation ...
by auscultating the heart.


Management

Management includes looking for and removing underlying cause, including medicines (such as a Calcium Channel blocker) and
inotropic An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction. The term ''inotro ...
therapy to return cardiac output back to normal. If highly symptomatic over a longer period ablation therapy may be the only viable option.


See also

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Pulsus bisferiens Pulsus bisferiens, also known as biphasic pulse, is an aortic waveform with two peaks per cardiac cycle, a small one followed by a strong and broad one. This reference illustrates the normal and abnormal spectral waveform. It is a sign (medicine), ...
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Dicrotic pulse In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the ne ...


References

Cardiovascular diseases {{Med-sign-stub