Heparin Dosing During Percutaneous Coronary Intervention and Obesity

ABSTRACT

Unfractionated heparin is the most common anticoagulant used during percutaneous coronary intervention. Practice guidelines recommend an initial weight-based heparin bolus dose between 70 and 100 U/kg to achieve target activated clotting time (ACT) of 250-300 seconds. The impact of severe obesity on weight-based heparin dosing is not well studied. We performed a retrospective analysis of 424 patients undergoing percutaneous coronary intervention who received heparin for anticoagulation. We collected detailed data on cumulative heparin administration and measured ACT values in this cohort. We performed separate analyses to identify clinical predictors that may affect dose-response curves. There was significant variability in dosing with mean dose of 103.9 ± 32-U/kg heparin administered to achieve target ACT ≥ 250 seconds. Women received higher initial heparin doses when adjusted for weight than men (97.6 ± 31 vs. 89 ± 28 U/kg, P = 0.004), and only 49% of patients achieved ACT ≥ 250 s with the initial recommended heparin bolus dose (70-100 U/kg). Lower heparin dose (U/kg) was required in obese patients to achieve target ACT. In multivariate linear regression analysis with ACT as dependent variable, after inclusion of weight-based dosing for heparin, body mass index was the only significant covariate. In conclusion, there is significant variability in the therapeutic effect of heparin, with a lower weight-adjusted heparin dose required in obese patients.

Cardiac Resynchronisation with Conduction System Pacing

To date, biventricular pacing (BiVP) has been the standard pacing modality for cardiac resynchronisation therapy. However, it is non-physiological, with the activation spreading between the left ventricular epicardium and right ventricular endocardium. Up to one-third of patients with heart failure who are eligible for cardiac resynchronisation therapy do not derive benefit from BiVP. Conduction system pacing (CSP), which includes His bundle pacing and left bundle branch area pacing, has emerged as an alternative to BiVP for cardiac resynchronisation. There is mounting evidence supporting the benefits of CSP in achieving synchronous ventricular activation and repolarisation. The aim of this review is to summarise the current options and outcomes of CSP when used for cardiac resynchronisation in patients with heart failure.

The psychoanalytic conceptualization of perinatal loss: a multidimensional model

Much has been learned about perinatal loss over the past 20 years through clinical investigations and quantitative research. However, a review of studies over the past decade reveals that perinatal loss is increasingly being seen in the same way as a death of any other member of the family, rather than as a unique bereavement. A comprehensive understanding of perinatal loss anchored in a theoretical framework of pregnancy is lacking. This article offers a multidimensional model for examining this loss by applying four psychoanalytic interpretations of pregnancy. 1) From the perspective of pregnancy ushering in the new developmental phase of parenthood, perinatal loss becomes a developmental interference, disrupting a significant milestone as well as causing isolation from peers. 2) In light of the usual recapitulation of earlier conflicts during pregnancy as noted by drive theory, perinatal loss may lead to an intensification of intrapsychic conflicts. 3) Understanding pregnancy as the creation of a specific person in an object relations model highlights the importance of mourning after perinatal death, as well as the need to tend to associated unresolved grief from earlier losses. 4) Finally, a model of narcissism describes how pregnancy reorganizes self-esteem, thereby delineating the intense narcissistic injury and rage that often follow perinatal loss. These multiple frameworks help to explain the many repercussions of this loss as well as to account for individual differences. Research findings are selectively reviewed to support the validity of this model. Conversely, this model may productively guide future avenues for research.

Perinatal loss. A critique of current hospital practices

Dramatic improvements in the hospital management of perinatal loss have taken place in the past 20 years. However, there has been no critical examination of current approaches. Four possible hazards of current hospital practice are described: 1) Institutionalization of bereavement: Instead of offering parents an empathic awareness of the unique dimensions of their perinatal loss, caregivers often interact according to detailed behavioral protocols. 2) Idealization of contact with the dead baby: This approach may equate actual physical contact with the dead child with the more complicated and variable process of mourning. 3) Homogenization of grief: Counselors tend to denigrate different grief responses by focusing on a preconceived grief reaction. Thus, they may mistakenly label many such reactions pathologic if they deviate from the rigidly prescribed "norm." 4) Lecturing the bereaved: Telling parents the "right" thing to do may deprive them of a crucial aspect of the process that empowers parents after they experience the helplessness associated with perinatal loss--that of making their own decisions. These problems are illustrated by a clinical vignette, and alternative approaches are explored.

Psychodynamics of perinatal loss

Medical and mental health professionals have been slow to recognize and treat the often traumatic impact of perinatal death. It has only been within the past ten years that researchers have begun to appreciate that a miscarriage, stillbirth or neonatal death can be a devastating loss to the parent, especially the mother (Berezin 1982; Borg and Lasker 1981; Friedman and Gladstein 1982; Peppers and Knapp 1980a). Bereaved mothers mourn pregnancy loss through the grieving process, which includes denial, yearning and despair, usually followed by recovery. Typical maternal reactions during the first months of grief are shock, disbelief, sleeplessness, irritability, crying, sadness, rage, anxiety, somatic distress and sometimes hallucinatory experience of the dead baby (Dunlop 1979; Giles 1970; Kennell et al. 1970; Kirkley-Best and Kellner 1982; Peppers and Knapp 1980b). This paper will explore the impact of perinatal death on the psychological resolution of pregnancy. In order to evaluate the outcome of maternal bereavement, the meanings of the perinatal death in the context of the revived conflicts and identifications occurring in the pregnancy will be considered. After presenting key concepts in the psychoanalytic interpretation of pregnancy, I will discuss the unique aspects of perinatal loss. A clinical case will then be described in some detail to illustrate an adaptive resolution of perinatal loss.