atrial standstill(redirected from sinoventricular rhythm)
cessation of atrial contractions, marked by absence of atrial waves in the electrocardiogram.
Synonym(s): auricular standstill
a condition of complete failure of the atria to contract. P waves are absent in all electrocardiogram surface leads, and A waves are absent in the jugular venous pulse and right atrial pressure tracings. Generally a junctional escape pacemaker maintains ventricular activity during atrial standstill.
atrial standstillA transient or permanent electrical atrial failure—and non-contractility of atria—which is seen in patients with familial amyloidosis and facioscapulohumeral dystrophy, possibly due to perineural infiltration.
Absent P waves.
Absent A waves.
Congenital atrial standstill is linked to a mutation of SCN5A, which encodes a voltage-gated sodium channel.
a·tri·al stand·still(ā'trē-ăl stand'stil)
Cessation of atrial contractions, marked by absence of atrial waves in the electrocardiogram.
pertaining to an atrium.
contraction of the atrial muscle; plays a part in ventricular filling and opening and closing of the A-V valves.
return of blood via the venae cavae and the pulmonary veins to the atria. Too slow a return means inadequate cardiac output, too slow emptying means an increase in central venous pressure and possibly the development of congestive heart failure. The rate varies normally with the cardiac cycle, being fastest during atrial diastole and slowest during atrial systole.
atrial natriuretic factor (ANF)
a peptide hormone found in cardiocytes of the right and left atria and released in response to increases in plasma volume. Plays a role in the regulation of blood pressure and volume, and in the excretion of water, sodium and potassium. Closely related or possibly identical substances include auriculin, atriopeptin, cardionatrin.
most often is a complication of endocardiosis and valvular insufficiency in dogs. The resulting acute pericardial hemorrhage may cause death from cardiac tamponade.
atrial septal defect
a congenital heart defect in which there is persistent patency of the atrial septum, owing to failure of closure of the ostium primum or ostium secundum.
complete lack of atrial contraction; ventricular function remains normal. Caused by hyperkalemia, extreme sinus bradycardia, digitalis toxicity and a congenital muscle disorder of dogs and cats.
see atrial contraction (above).