Fetal premature atrial contractions
Updates to Article Attributes
Fetal premature atrial contractions are a type of extrasystoles that can be occasionally detected in fetal heart monitoring. They along with fetal premature ventricular contractions (PVC's) account for the majority of in utero rhythm disturbances.
Terminology
Premature atrial contractions may occur at a 1:1 ratio with sinus beats (a pattern of bigeminy), with every second sinus beat (trigeminy) or every third sinus beat (quadrigeminy). Conduction to the ventricles may or may not occur; in the latter instance, no ventricular systole will be observed following atrial systole, and the duration of the pause (non-compensatory, with the total length of the pause less than twice the expected interval between atrial contractions) may be used to distinguish PACs from ectopic beats of a ventricular origin.
Pathology
They may arise from immaturity in the fetal cardiac conduction system 2. The conductions arise in the atrium and can be either transmitted to the ventricles (conduced PACs) or blocked (non-conducted PACs).
Associations
- in 1-2% of cases, they can be associated with a congenital cardiac anomaly
Significance
They are benign and usually self-limiting and do not generally compromise cardiac function. In most cases, they disappear spontaneously in utero.
Radiographic features
Ultrasound
M-mode interrogation of atrial and ventricular contractions may proceed with the placement of the M-mode line in a plane transecting atrial and ventricular walls simultaneously, displaying their respective contractions graphically over time. Alternatively, pulsed wave Doppler may be used to simultaneously insonate the left ventricular outflow tract and mitral inflow velocities, yielding diastolic "E" and "A" waves on one side of the baseline, and systolic "V" waves on the opposite side 6.
The presence of premature atrial contractions may be suspected when an atrial contraction (on M-mode) or an A wave (spectral Doppler) occurs earlier than would be expected based on the preceding intervals between atrial activity 5.
The PAC may be classified as non-conducted if it is not followed by a V wave or ventricular contraction. A non-compensatory pause should be noted following the PAC; blocked premature atrial contractions may mimic AV block (atrial rate > ventricular rate) but, unlike PACs, AV blocks maintain consistent intervals between atrial events 4.
See also
-<p><strong>Fetal premature atrial contractions </strong>are a type of extrasystoles that can be occasionally detected in fetal heart monitoring. They along with <a href="/articles/fetal-premature-ventricular-contractions">fetal premature ventricular contractions (PVC's) </a>account for the majority of in utero rhythm disturbances.</p><h4>Pathology</h4><p>They may arise from immaturity in the fetal cardiac conduction system <sup>2</sup>. The conductions arise in the atrium and can be either transmitted to the ventricles or blocked.</p><h5>Associations</h5><ul><li>in 1-2% of cases, they can be associated with a <a href="/articles/congenital-cardiovascular-anomalies">congenital cardiac anomaly</a>-</li></ul><h4>Significance </h4><p>They are benign and usually self-limiting and do not generally compromise cardiac function. In most cases, they disappear spontaneously in utero.</p><h4>See also</h4><ul>- +<p><strong>Fetal premature atrial contractions </strong>are a type of extrasystoles that can be occasionally detected in fetal heart monitoring. They along with <a href="/articles/fetal-premature-ventricular-contractions">fetal premature ventricular contractions (PVC's) </a>account for the majority of in utero rhythm disturbances.</p><h4>Terminology</h4><p>Premature atrial contractions may occur at a 1:1 ratio with sinus beats (a pattern of bigeminy), with every second sinus beat (trigeminy) or every third sinus beat (quadrigeminy). Conduction to the ventricles may or may not occur; in the latter instance, no ventricular systole will be observed following atrial systole, and the duration of the pause (non-compensatory, with the total length of the pause less than twice the expected interval between atrial contractions) may be used to distinguish PACs from ectopic beats of a <a title="Fetal premature ventricular contraction (FPVC)" href="/articles/fetal-premature-ventricular-contractions">ventricular</a> origin.</p><h4>Pathology</h4><p>They may arise from immaturity in the fetal cardiac conduction system <sup>2</sup>. The conductions arise in the atrium and can be either transmitted to the ventricles (conduced PACs) or blocked (non-conducted PACs). </p><h5>Associations</h5><ul><li>in 1-2% of cases, they can be associated with a <a href="/articles/congenital-cardiovascular-anomalies">congenital cardiac anomaly</a>
- +</li></ul><h4>Significance </h4><p>They are benign and usually self-limiting and do not generally compromise cardiac function. In most cases, they disappear spontaneously in utero.</p><h4>Radiographic features</h4><h5>Ultrasound</h5><p><a title="M-mode (ultrasound)" href="/articles/m-mode-ultrasound">M-mode</a> interrogation of atrial and ventricular contractions may proceed with the placement of the M-mode line in a plane transecting atrial and ventricular walls simultaneously, displaying their respective contractions graphically over time. Alternatively, <a title="Pulsed wave Doppler" href="/articles/spectral-doppler-ultrasound">pulsed wave Doppler</a> may be used to simultaneously insonate the <a title="Left ventricular outflow tract view (fetal echocardiogram)" href="/articles/left-ventricular-outflow-tract-view-fetal-echocardiogram">left ventricular outflow tract</a> and <a title="Diastolic dysfunction (point of care ultrasound)" href="/articles/diastolic-dysfunction-point-of-care-ultrasound">mitral inflow</a> velocities, yielding diastolic "E" and "A" waves on one side of the baseline, and systolic "V" waves on the opposite side <sup>6</sup>. </p><p>The presence of premature atrial contractions may be suspected when an atrial contraction (on M-mode) or an A wave (<a title="Spectral Doppler (ultrasound)" href="/articles/spectral-doppler-ultrasound">spectral Doppler</a>) occurs earlier than would be expected based on the preceding intervals between atrial activity <sup>5</sup>.</p><p>The PAC may be classified as non-conducted if it is not followed by a V wave or ventricular contraction. A non-compensatory pause should be noted following the PAC; blocked premature atrial contractions may mimic <a title="Fetal complete AV block" href="/articles/fetal-complete-atrioventricular-block">AV block</a> (atrial rate > ventricular rate) but, unlike PACs, AV blocks maintain consistent intervals between atrial events <sup>4</sup>.</p><h4>See also</h4><ul>
References changed:
- 4. Alfred Z. Abuhamad, Rabih Chaoui. A Practical Guide to Fetal Echocardiography. (2012) <a href="https://books.google.co.uk/books?vid=ISBN9781451147803">ISBN: 9781451147803</a><span class="ref_v4"></span>
- 5. Bravo-Valenzuela NJ, Rocha LA, Machado Nardozza LM, Araujo Júnior E. Fetal cardiac arrhythmias: Current evidence. (2018) Annals of pediatric cardiology. 11 (2): 148-163. <a href="https://doi.org/10.4103/apc.APC_134_17">doi:10.4103/apc.APC_134_17</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/29922012">Pubmed</a> <span class="ref_v4"></span>
- 6. Bravo-Valenzuela NJ, Rocha LA, Machado Nardozza LM, Araujo Júnior E. Fetal cardiac arrhythmias: Current evidence. (2018) Annals of pediatric cardiology. 11 (2): 148-163. <a href="https://doi.org/10.4103/apc.APC_134_17">doi:10.4103/apc.APC_134_17</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/29922012">Pubmed</a> <span class="ref_v4"></span>
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