Undersensing of VF in a Patient With Optimal R Wave Sensing During Sinus Rhythm

We describe a case of potentially fatal undersensing of VF by a third generation ICD with predetermined automatic gain control. In this patient, ventricular sensing was optimal, as R wave amplitudes during sinus rhythm were at least 16 mV. Cyclical, high amplitude signals during VF elevated the sensing floor to such an extent that complete undersensing of subsequent lower amplitude local electrograms occurred. This led to bradypacing and complete ICD therapy failure. Therefore, high R wave amplitudes during sinus rhythm do not warrant flawless sensing during VF. (PACE 2004; 27[Pt. I] 833–834)     

Guidelines for the management of hypertensive disorders of pregnancy 2008

This is the Executive Summary of updated guidelines developed by the Society of Obstetric Medicine of Australia and New Zealand for the management of hypertensive diseases of pregnancy. They address a number of challenging areas including the definition of severe hypertension, the use of automated blood pressure monitors, the definition of non-proteinuric pre-eclampsia and measuring proteinuria. Controversial management issues are addressed such as the treatment of severe hypertension and other significant manifestations of pre-eclampsia, the role of expectant management in pre-eclampsia remote from term, thromboprophylaxis, appropriate fluid therapy, the role of prophylactic magnesium sulfate and anaesthetic issues for women with pre-eclampsia. The guidelines stress the need for experienced team management for women with pre-eclampsia and mandatory hospital protocols for treatment of hypertension and eclampsia. New areas addressed in the guidelines include recommended protocols for maternal and fetal investigation of women with hypertension, preconception management for women at risk of pre-eclampsia, auditing outcomes in women with hypertensive diseases of pregnancy and long-term screening for women with previous pre-eclampsia.     

Prediction of pregnancy-induced hypertensive disorders by angiotensin II sensitivity and supine pressor test

Summary. An angiotensin II sensitivity test and a supine pressor test were done consecutively at 28 weeks gestation in 90 healthy, normotensive nulliparous women. None of the supine pressor tests was positive, applying the predefined threshold of a rise of 20 mmHg in diastolic blood pressure after rolling over; nine tests were positive using a corrected 9 mmHg cut-off level. Ten women had a positive angiotensin sensitivity test using a threshold of the effective pressor dose of 8 ng/kg/min; 22 women were positive using an effective pressor dose of 10 ng/kg/min. Later in pregnancy 12 women (13%) developed pregnancyinduced hypertensive disease (PIH). The specificity of both tests of predicting the development of PIH was about 90%. The sensitivity of the angiotensin sensitivity test at the 10 ng/kg/min level was 92%. Because of its low sensitivity of 25% the supine pressor test appears to have no value for the prediction of PIH. There was a significant positive association between angiotensin IT refractoriness and birthweight.