tailieunhanh - Fetal Electrocardiography – part 8

Công việc này đã tấn công mạnh mẽ Rosen và Westgate (1996) đã chỉ ra rằng chất lượng tín hiệu đã không được đánh giá và các vị trí điện cực không giống như những người sử dụng trong công việc trước đây về. | Time Intervals and Morphology of the Fetal ECG 107 concluded that in fetal lambs the T QRS ratio failed to predict fetal hypoxaemia and fetal acidosis. This work was strongly attacked by Rosen and Westgate 1996 who pointed out that signal quality had not been assessed and the electrode placements were not the same as those used in previous experimental work. They also claimed that many of the animals exhibited chronically elevated waveforms before the onset of hypoxia and the application of linear regression to the analysis was inappropriate. De Haan replied by pointing out that the Stan recorder checks its own quality and that the objective of the study was to ascertain the diagnostic power of the T QRS ratio to predict fetal well-being and in particular to look at the assessment during periods of stable heart rate rather than during episodes of bradycardia. The issue of the value of the current use of the FECG morphological characteristics and time intervals for the prediction of fetal compromise remains promising but unresolved. Chapter 7 FETAL CARDIAC ARRHYTHMIAS Disorders of Cardiac Rhythms in the Fetus In the normal heart depolarisation follows activation of the sino-atrial node. When depolarisation originates in other parts of the myocardium or the conduction system is blocked at some point then disorders of rhythm occur. The same principles are obtained in the fetal heart with the difference that the mother controls the fetal environment and that the frequency of occurrence of different abnormalities follows a different profile in the fetus. Cardiac arrhythmias have their origins in three places the atrial muscle the region around the AV node . nodal or junctional the ventricular muscle. Sinus rhythm atrial rhythm and junctional or nodal rhythm are classified as supraventricular rhythms. The depolarisation wave spreads to the ventricles in the normal way and therefore the QRS complex is normal and narrow with the exceptions of bundle branch block and .