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A Olive

Publications and source records attributed to A Olive.

16 recordsLinked to original sources
PubMed1999

Automatic capture verification by charge-neutral sensing.

Automatic capture verification can prolong pulse generator longevity and increase patient safety. However, the detection of evoked response following pacing is complicated due to afterpotentials caused by polarization of electrodes. This study describes a new capture verification scheme, which neutralizes the charges between the pacing electrodes. The hypothesis of the charge-neutral sensing is that the afterpotentials in the ring and the tip are opposite in polarity when pacing in a bipolar mode between ring and tip. Summing the unipolar signals sensed at the tip and the ring should effectively cancel the afterpotentials. This scheme was implemented in an external computer based system and tested during pacemaker implant/replacement on 23 patients during VVI pacing (17 acutely implanted leads and 6 chronic leads). Surface ECG was recorded to provide a marker for capture and noncapture. The pacing voltage was gradually decreased until a noncapture beat was noted. To avoid fusion beats, the pacing rate was programmed approximately 50% higher than the intrinsic rate. The evoked response was high pass filtered and the integral average was calculated for both capture and noncapture beats. The system signal to noise ratio (SNR) was expressed as ratio of the minimum integral average of all capture beats to the maximum integral average of all noncapture beats. The system SNR was 8.6 +/- 1.3 (mean +/- S.E.M; range 1.5-22.8), indicating that the charge-neutral sensing method has, on average, a ninefold safety margin in providing capture verification. Further, evaluation is needed to fully assess this feature in patients with chronic leads.

Aged↗
PubMed1995

G-CSF after autologous bone marrow transplantation for malignant diseases in children. Spanish Working Party for Bone Marrow Transplantation in Children.

The use of recombinant human granulocyte-stimulating factor (G-CSF) has been shown to effectively accelerate granulocytic recovery after autologous bone marrow transplantation (BMT) in adults. The experience, however, is limited in children. We evaluated the hematopoietic reconstitution in 41 consecutive children undergoing autologous BMT for hematologic malignancies (21 acute lymphoblastic leukemia, five non-Hodgkin's lymphoma) and solid tumours (seven neuroblastoma, two brain tumor, three Ewing's sarcoma, two Wilms' tumor, one rhabdomyosarcoma). Their ages ranged from 2 to 16 years (mean 7.2 years). rhG-CSF was given at a dose of 10 micrograms/kg/day i.v. in a 2h infusion from day +1 until +28 or until the absolute neutrophil count (ANC) was > 1 x 10(9)/L. These patients were compared with a similar historical control group of 38 children who did not receive rhG-CSF after autologous BMT. The number of cells infused was similar in both groups. At the dose and schedule used in the present study, rhG-CSF was well tolerated and no side-effects were observed. The number of cell infused was similar in both groups. At the dose and schedule used in the present study, rhG-CSF was well tolerated and no side-effects were observed. Our data show that rhG-CSF accelerates engraftment and reduces the number of febrile days and antibiotic use. Furthermore, patients who were treated had less infections.

Adolescent↗
PubMed1994

Comparison of subcutaneous unfractionated heparin with a low molecular weight heparin (Fragmin) in patients with venous thromboembolism and contraindications to coumarin.

Intravenous heparin followed by oral anticoagulant therapy (e. g. with coumarin) is still the most widely used treatment for deep venous thromboembolism. Self-administered subcutaneous injections of heparin have been thought of as a promising alternative to coumarin, but the high doses required for ongoing prophylaxis have raised concerns about the possible development of bone disease. Certainly, long-term heparin therapy has been reported to cause osteoporosis in both laboratory animals and humans. This study aimed to compare the efficacy and safety of unfractionated (UF) heparin with that of a low molecular weight heparin (Fragmin, Kabi Pharmacia) in the prevention of recurrent deep venous thrombosis (DVT) and pulmonary embolism (PE) in a consecutive series of patients with contraindications to coumarin therapy. The patients comprised 40 men and 40 women, aged between 19 and 92 years (mean age, 68 years). They had all previously been diagnosed as having acute DVT and had been treated with conventional doses of heparin while in hospital. All patients had at least one of the following conditions: recent blood loss (either spontaneous or during admission while receiving heparin therapy); active gastroduodenal ulcer disease; psychological or physical inability or unwillingness to understand and accept the need for regular laboratory monitoring during coumarin treatment; chronic alcoholism; dementia; pregnancy; recent neurosurgery, and pericardial effusion; or were over 80 years of age. They were randomly allocated to receive either UF heparin, 10,000 IU s.c. b.d., or Fragmin, 5000 IU anti-Factor Xa s.c. b.d., for a period of 3-6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Anti-intrinsic factor antibodies in systemic lupus erythematosus.

As the co-existence of pernicious anaemia (PA) and systemic lupus erythematosus (SLE) has been repeatedly reported, we have investigated the presence of anti-intrinsic factor antibodies (IFAb), the immunological hallmark of PA, in patients diagnosed with SLE. Serum cobalamin levels and IFAb were determined in 30 women diagnosed with SLE as well as in 45 controls. Cobalamin levels were low in 7/30 patients. IFAb were detected in 3/30 sera from patients but in none of the control sera. The presence of IFAb was associated with a low cobalamin concentration, anaemia and macrocytosis in only one patient. There was no evident relationship between the presence of IFAb and serological markers of SLE. We conclude that IFAb may appear in SLE patients, although the cobalamin deficiency described in SLE seems to be due to the presence of IFAb in only a minority of cases.

Adolescent↗
PubMed1989

The feasibility of utilizing the systolic pre-ejection interval as a determinant of pacing rate.

Rate-modulated pacing modes adjust the stimulus rate by responding to sensed alterations in physiologic indexes of metabolic demand. This study was designed to determine whether right ventricular pre-ejection interval, measured in patients by a prototype pacemaker system capable of tracking intraventricular volume, changes predictably with exercise and, if so, whether it can be used in an algorithm to vary heart rate appropriately. This system utilizes intraventricular electrical impedance measurements of injected microampere currents to determine intracavitary volume changes. Five pacemaker-dependent patients underwent temporary insertion of a tripolar electrode connected to an external device that sensed cardiac signals, generated an impedance wave form and produced stimuli at rates dependent on pre-ejection interval. Pre-ejection interval did not change as a result of variations in pacing rate itself (347 +/- 41 ms at 70 beats/min versus 321 +/- 19 ms at 130 beats/min), but consistently decreased during graded exercise (by 23% from baseline). During rate-modulated pacing based on pre-ejection interval, heart rate significantly increased during exercise compared with ventricular demand pacing (by 46 +/- 6 versus 7 +/- 6 beats/min, respectively), and increased appropriately during burst exercise. Thus, the pre-ejection interval appears to be a specific, reliable physiologic determinant of pacing rate during exertion, which may be applicable in implantable rate-modulated pacemakers.

Adult↗
PubMed1981

Relation between postoperative antithrombin III concentrations and site of operation.

Antithrombin III concentrations were measured in 305 patients before and at intervals after operation for up to 12 days. The blood concentrations fell significantly after both major and minor surgery, but there was no relation between the expected degree of surgical trauma or the amount of blood transfused and the fall in concentration of antithrombin III. Some surgical procedures such as cholecystectomy, laparotomy, hernia repair, highly selective vagotomy, and transurethral resection of the prostate were associated with a greater depletion of antithrombin III than were other common operations and it is suggested that there are factors related to the actual site of the operation which affect the concentration of circulating antithrombin III in the postsurgical period.

Antithrombin III↗