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Biomedical subjects

R Pifarre

Publications and source records attributed to R Pifarre.

At least 19 recordsLinked to original sources
PubMed1999

Failure of early heparin cessation as treatment for heparin-induced thrombocytopenia.

PURPOSE: The complications of heparin-induced thrombocytopenia include thrombosis and death. The purpose of the study was to determine whether early heparin cessation can prevent these outcomes. SUBJECTS AND METHODS: We performed a retrospective analysis of consecutive patients with heparin-induced thrombocytopenia diagnosed by platelet aggregometry. Demographic, clinical, and laboratory findings were compared in patients by whether heparin treatment was stopped early (< or = 48 hours) or late (>48 hours) after the onset of thrombocytopenia, as well as between patients with and without thrombosis. Thrombocytopenia was defined as a 50% decline in baseline platelet counts or an absolute platelet count < 100,000/mm3. RESULTS: Of the 113 patients, 38% developed thrombosis and 27% died. One-half of patients had thrombosis diagnosed >24 hours after heparin cessation. No difference in thrombosis or mortality was found in the 40 patients with early heparin cessation [mean (+/-SD) time of cessation 0.7 +/- 0.6 days] compared with the 73 patients with late heparin cessation (5 +/- 3 days). Thrombosis >24 hours after heparin cessation occurred in 61% of the patients in the early group and in 40% of the late group (P = 0.17). In a multivariate analysis, only a lower nadir of the platelet count (percent of baseline) was associated with thrombosis. Neither thrombosis nor the time to heparin cessation were associated with mortality. CONCLUSIONS: Early heparin cessation was not effective in reducing morbid events in patients with heparin-induced thrombocytopenia. Treatment strategies other than heparin cessation alone should be considered in patients with this condition.

Adult↗
PubMed1999

Inadequacy of current prevention strategies for heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia is one of the most difficult problems facing clinicians today. Despite recent understanding of the pathophysiology of this disorder, there are many unresolved issues about diagnosis, prevention, and treatment. In this article, difficulties physicians encounter when faced with a suspected heparin-induced thrombocytopenia patient will be reviewed as well as our experience in 113 patients with heparin-induced thrombocytopenia which highlights the failure of current preventive strategies for heparin-induced thrombocytopenia. The experience of using warfarin in 51 patients with heparin-induced thrombocytopenia will also be reviewed.

Fibrinolytic Agents↗
PubMed1996

Natural history of allograft coronary arteriopathy: a retrospective study of 54 patients over a 8 1/2-year period.

A total of 288 patients underwent heart transplantation at Loyola University Medical Center over a 8 1/2-year period starting in March, 1984. Of these patients, 54 were identified as having allograft coronary arteriopathy. Diagnosis was made on the basis of abnormal findings on coronary angiography in 44 patients; either an autopsy or explanted heart revealed the diagnosis in the remainder. A total of 279 abnormal lesions were identified by coronary angiography, and over 70% of these stenoses were discrete and located in large epicardial vessels. The left ventricular ed-diastolic pressure demonstrated a steady rise over time (2.5 mmHg/year), and also correlated with the degree of allograft coronary arteriopathy stenosis. The rate of stenosis progression was 33% per year from the time of initial allograft coronary arteriopathy development. Actuarial survival rate was lower than that of patients with arteriopathy. In conclusion, first, the majority of allograft coronary arteriopathy stenoses detected on coronary angiography are discrete, involve large epicardial vessels, and progress rapidly over time. Second, left ventricular end-diastolic pressure seems to reflect the degree of allograft coronary arteriopathy stenosis, and may prove to be a useful indicator of left ventricular dysfunction related to allograft coronary arteriopathy. Third, patients with allograft coronary arteriopathy show a decreased actuarial survival rate.

Actuarial Analysis↗
PubMed1996

Bridge to transplantation with the CardioWest total artificial heart: the international experience 1993 to 1995.

BACKGROUND: After reapproval by the Food and Drug Administration of the CardioWest total artificial heart for clinical investigation, an international study was started in January 1993 to ascertain the safety and efficacy of this device for bridging to heart transplantation. To date, 40 devices have been implanted in five centers. METHODS: Retrospective data collection from participating centers provided enough material for analysis of patient selection, patient survival, adverse events, and comparison with contemporary devices used for bridge to transplantation. RESULTS AND CONCLUSIONS: Twelve patients (30%) died after implantation and before transplantation after an average of 10.6 +/- 10 days of support. The major cause of death in this group was multiorgan failure. Twenty-eight patients (70%) were supported 36 +/- 36 days before transplantation. There were two deaths after transplantation (1 rejection, 1 multiorgan failure) leaving 26 patients (65% of the total patients and 93% of those who were transplanted) who survived to discharge from the hospital. There was one late death from rejection at one month post discharge. The mean survival time of the 25 surviving patients is 12 months. These results compare favorably with those of other contemporary devices used for bridge to transplantation.

Adult↗
PubMed1995

A multicenter, double-blind, placebo-controlled trial of aprotinin for reducing blood loss and the requirement for donor-blood transfusion in patients undergoing repeat coronary artery bypass grafting.

BACKGROUND: Aprotinin is a serine protease inhibitor that reduces blood loss and transfusion requirements when administered prophylactically to cardiac surgical patients. To examine the safety and dose-related efficacy of aprotinin, a prospective, multicenter, placebo-controlled trial was conducted in patients undergoing repeat coronary artery bypass graft (CABG) surgery. METHODS AND RESULTS: Two hundred eighty-seven patients were randomly assigned to receive either high-dose aprotinin, low-dose aprotinin, pump-prime-only aprotinin, or placebo. Drug efficacy was determined by the reduction in donor-blood transfusion up to postoperative day 12 and in postoperative thoracic-drainage volume. The percentage of patients requiring donor-red-blood-cell (RBC) transfusions in the high- and low-dose aprotinin groups was reduced compared with the pump-prime-only and placebo groups (high-dose aprotinin, 54%; low-dose aprotinin, 46%; pump-prime only, 72%; and placebo, 75%; overall P = .001). The number of units of donor RBCs transfused was significantly lower in the aprotinin-treated patients compared with placebo (high-dose aprotinin, 1.6 +/- 0.2 U; low-dose aprotinin, 1.6 +/- 0.3 U; pump-prime-only, 2.5 +/- 0.3 U; and placebo, 3.4 +/- 0.5 U; P = .0001). There was also a significant difference in total blood-product exposures among treatment groups (high-dose aprotinin, 2.2 +/- 0.4 U; low-dose aprotinin, 3.4 +/- 0.9 U; pump-prime-only, 5.1 +/- 0.9 U; placebo, 10.3 +/- 1.4 U). There were no differences among treatment groups for the incidence of perioperative myocardial infarction (MI). CONCLUSIONS: This study demonstrates that high- and low-dose aprotinin significantly reduces the requirement for donor-blood transfusion in repeat CABG patients without increasing the risk for perioperative MI.

Aged↗
PubMed1995

Safety of patent ductus arteriosus closure in premature infants without tube thoracostomy.

During a 30-month period, 34 premature infants underwent surgical closure of a patent ductus arteriosus. The mean gestational age at birth was 25 +/- 0.3 weeks and the mean age at the time of operation was 3 +/- 0.3 weeks (mean weight, 829 +/- 54 g). Indomethacin therapy had failed in 32 patients, and 2 had contraindications to its use. The initial 8 patients had parascapular incision and ligation of the patent ductus arteriosus; the last 26 patients had a short transaxillary incision and clipping. The average duration of the operation from the time of incision to skin closure was 36 +/- 2 minutes (range, 15 to 65 minutes). One patient (3%) needed chest tube insertion intraoperatively because of visceral pleura disruption. Two patients (5.8%) had a "small pneumothorax" (< 10% of the lung field) that resolved within 24 hours. There was no morbidity or mortality directly related to the operative procedure, although 3 patients (8.8%) ultimately died from problems related to their severe prematurity. We conclude that surgical closure of patent ductus arteriosus without chest tube drainage can be accomplished safely in premature infants. Postoperative nursing care is simplified and the cost is reduced because the need for the chest tube and drainage system is eliminated and the number of chest radiograms needed postoperatively is reduced.

Blood Loss, Surgical↗
PubMed1995

Flow cytometric evaluation of platelet activation by ionic or nonionic contrast media and modulation by heparin and recombinant hirudin.

RATIONALE AND OBJECTIVES: The purpose of this study was to investigate the platelet activation properties of ionic and nonionic contrast media in native heparinized or hirudinized human blood using flow cytometric analysis techniques. MATERIALS AND METHODS: Freshly drawn human blood samples were incubated at 37 degrees C with ionic (Hexabrix and Angiovist) and non-ionic (Isovue and Omnipaque) contrast media for varying periods of time. Using fluorescent monoclonal antibodies to platelet surface receptors glycoprotein IIIa and with granule membrane protein-140, platelet activation was measured in whole blood using flow cytometry. Platelet factor 4 and thromboxane B2 levels also were measured. RESULTS: Dose- and time-dependent platelet activation was observed in nonionic, but not in ionic, contrast media (P < 0.05). Whole blood drawn into heparin or hirudin showed reduced platelet activation in the presence of contrast media compared with nonanticoagulated whole blood. Platelet factor 4 and thromboxane B2 levels showed similar results. Significant platelet activation was seen by flow cytometry in high (2000 mOsmol/kg), but not in lower osmolality (800 mOsmol/kg) controls for ionic and nonionic contrast media, respectively (P < 0.001). CONCLUSION: This study suggests that nonionic contrast media use is associated with significant levels of platelet activation, and that heparin or recombinant hirudin (where heparin is contraindicated) is preferable for use with nonionic contrast media, as these anticoagulants reduce contrast media induced platelet activation.

Contrast Media↗
PubMed1995

Reduced transplant lung volumes after single lung transplantation for chronic obstructive pulmonary disease.

Single lung transplantation is now an extremely successful option for the treatment of end-stage chronic obstructive pulmonary disease (COPD). This procedure involves placing a normal sized lung in a hyperinflated hemithorax. Preliminary observations of these patients suggest that the transplanted lung volume is smaller than expected and often the native (COPD) lung increases in volume. The purpose of this investigation was to quantify the volume contributions of the transplant and native lung to the total lung capacity. In seven patients who underwent single lung transplant for end-stage COPD the transplant and native lung volumes were measured by computer-analyzed planimetry immediately after transplant and the following 6 mo post-transplant. The transplant lung volume was smaller than predicted immediately after transplant at only 33 +/- 5% (mean +/- SD) of predicted TLC. This did not change significantly over the next 6 mo. Native lung volume increased following transplant to 74 +/- 19% predicted TLC at 1 mo and 80 +/- 16% at 6 mo. Five of the seven patients subsequently underwent measurement of pleural pressures at TLC. The mean static pleural pressure at TLC was low at -16 +/- 5.1 cm H2O. In summary, following single lung transplantation for COPD the transplanted lung is significantly restricted. We conclude that the likely mechanism of this restriction is due to low transpulmonary pressure generation.

Female↗
PubMed1994

Risk/benefit ratio of perioperative OKT3 in cardiac transplantation.

To evaluate the risk/benefit ratio of perioperative OKT3 in cardiac transplant patients receiving triple-drug immunosuppression, patients who underwent cardiac transplantation between July 1, 1988 and December 31, 1989 (n = 33) and who received perioperative OKT3 were retrospectively compared with patients who underwent transplantation between January 1, 1990 and June 30, 1991 (n = 46), and who received no perioperative anti-T cell therapy. To allow similar follow-up, data were analyzed through June 30, 1990 for the OKT3 group and through December 31, 1991 for the no anti-T cell therapy group. Patients in the no anti-T cell therapy group waited longer for a donor organ; other pretransplant characteristics did not differ. The azathioprine dose 1 month after transplant was higher in the no anti-T cell therapy group (144 +/- 63 mg vs 109 +/- 55 mg, p = 0.016); other post-transplant immunosuppression was similar. The incidence of total and treated rejection and the time to the first rejection did not differ between the groups. The OKT3 group had a higher number of infections (0.8 +/- 0.9 vs 0.3 +/- 0.3, p = 0.006) and intravenously treated infections (0.5 +/- 0.6 vs 0.1 +/- 0.2, p = 0.004) per patient per month. Cytomegalovirus infection developed in 46% of the OKT3 group versus 22% of the no anti-T cell therapy group (p = 0.025). Patient survival did not differ between the groups. Thus, an immunosuppressive regimen that includes perioperative OKT3 increases infections, especially cytomegalovirus infections, without decreasing or delaying rejection or increasing survival.

Adult↗
PubMed1994

Chronic cardiac rejection masking as constrictive pericarditis.

The hemodynamic changes consistent with constrictive pericarditis are often encountered in patients who have undergone cardiac transplantation. We describe here 4 patients who underwent pericardiectomy after cardiac transplantation. All were found to have evidence of a thickened and constricting peel of pericardium at surgical exploration. Their postoperative clinical courses were variable. One patient with primarily effusive constriction experienced marked improvement. Three patients failed to show clinical improvement and had persistently elevated atrial and ventricular end-diastolic pressures. A coexisting restrictive cardiomyopathy secondary to chronic rejection, coronary arteriopathy, or long-standing constriction may have been the cause of this poor outcome. Many patients with transplanted hearts exhibit evidence of poor diastolic ventricular compliance without evidence of classic constriction; some manifest both the restrictive and constrictive components. The careful selection of patients with constrictive pericarditis can optimize the outcome.

Adult↗
PubMed1994

Recognition and management of accessory mitral tissue causing severe subaortic stenosis.

Failure to recognize the presence of accessory mitral tissue causing subaortic stenosis can lead to not only the performance of inappropriate operations, but the persistence and recurrence of obstruction or even death. Over a 12-month period, we treated 2 children with severe subaortic stenosis caused by accessory mitral tissue. In 1 patient, who was 4 years old, the echocardiogram showed the accessory mitral tissue to be attached to the anterior mitral leaflet and ballooning into the subaortic area. The other patient, as a newborn, underwent simultaneous repair of a complete canal defect and coarctation. Two years later, the patient was seen because of syncopal episodes, progressive mitral insufficiency, and subaortic stenosis thought to be caused by anterior displacement of the anterior mitral leaflet. Mitral valvuloplasty and a conal enlargement procedure were planned. Intraoperatively, after the mitral valvuloplasty had been done, the subaortic stenosis was found to be due to a tight subaortic ring formed by accessory mitral tissue located at the septum and its fibrous extension to the anterior mitral leaflet. In both patients, excision of the accessory mitral and fibrous tissues resulted in a wide-open subaortic area. Both patients had an uneventful hospital course, and follow-up echocardiography showed no noteworthy residual left ventricular outflow gradient. We believe that increased awareness and sophisticated echocardiographic techniques should lead to an increased recognition of accessory mitral tissue causing subaortic stenosis. Simple resection of the accessory mitral tissue and its secondary fibrous tissues can be curative.

Angiography↗
PubMed1994

Measurement of right ventricular volume in human explanted hearts using ultrafast cine computed tomography.

The quantitative measurement of right ventricular (RV) volume has been attempted by a number of methods, including nuclear magnetic resonance imaging, contrast angiography, echocardiography, and radionuclide angiography. All of these methods have limitations. Ultrafast cine computed tomographic (CT) scan is a new technology that may have an important role in on-line ventricular volume measurements. Twelve human explanted hearts, fixed in formalin, were subjected to ultrafast cine CT scans to estimate RV volume. The volumes derived from the CT scans were compared with actual fluid volumes needed to fill the RV volume measurements. All measurements were conducted independently by two observers. Actual RV volumes in the 12 hearts ranged from 29.8 ml to 174.6 ml. A strongly significant correlation between actual volume and CT volume was seen (r = 0.99). Agreement between observers was also seen to be highly significant (r = 0.992). Limitations to accurate in vivo assessment due to bolus injection of contrast medium might include alterations in ventricular pressure change. Similarly, differentiation of the endocardial border with contrast may not be as sharp as that with an air-tissue interface. This study demonstrates that RV volumes can be reliably determined by ultrafast cine CT scans in explanted hearts. On-line systolic and diastolic volumes and thus stroke volume, ejection fraction, etc, can be accurately defined independent of cardiac orientation. This technique offers opportunities to study ventricular function under various conditions.

Cardiac Volume↗
PubMed1994

Ventricular dysfunction in norepinephrine-induced cardiomyopathy.

Cardiac dysfunction resulting from norepinephrine-induced cardiomyopathy has not been fully investigated. This study evaluates acute and chronic changes in systolic and diastolic function at three levels of norepinephrine (NE)-induced injury. Rabbits were infused with saline or 2, 4, or 6 micrograms/kg/min NE for 90 min. Ventricular function was assessed immediately after infusion or at 48 hr using the isolated non-ejecting heart preparation. Hearts were perfused at 10 ml/min/g with Krebs-Henseleit buffer. After baseline measurements, hearts were perfused with NE (10(-10) to 10(-7) M). Steady state left ventricular pressure (LVP), +dP/dt, and -dP/dt were recorded at baseline and each NE concentration. NE infusion acutely depressed baseline LV systolic function. Decreases in LVP and +dP/dt were inversely related to dose of infused NE. By 48 hr, LVP and +dP/dt improved slightly in all NE groups but improvement was significant only in hearts from rabbits infused with 4 micrograms NE. Systolic function of hearts from animals infused with 6 micrograms NE remained depressed. Diastolic (-dP/dt) function was impaired following NE infusion when compared to saline treated hearts and did not improve within 48 hr. Although baseline function is depressed, myopathic hearts increased ventricular function the same amount as normal hearts at 10(-7) M NE. These findings demonstrate a) impairment in LV systolic and diastolic function acutely after NE infusion, b) improvement in systolic function within 48 hr, c) ability to increase contractility in response to NE is not impaired, and d) recovery of systolic function precedes improvement in diastolic function.

Animals↗
PubMed1994

Survival and functional outcome after single and bilateral lung transplantation. Loyola Lung Transplant Team.

BACKGROUND: The experience at Loyola University Chicago was retrospectively reviewed to evaluate survival and functional outcome after single lung transplantation (SLT) and bilateral lung transplantation (BLT). METHODS: Ninety patients underwent lung transplantation at Loyola University Chicago between April 1990 and December 1993. Mean age was 45 years (range, 13 to 66 years). Fifty percent were male. Pre-lung transplant pulmonary diseases were as follows: emphysema and/or chronic obstructive pulmonary disease in 43 patients, pulmonary fibrosis in 13, cystic fibrosis in 14, pulmonary hypertension in eight, repeated transplantation for obliterative bronchiolitis in four, bronchiectasis in two, bronchoalveolar cell carcinoma in two, sarcoidosis in one, primary obliterative bronchiolitis in one, histiocytosis X in one, and lymphangiomyomatosis in one. Fifty-seven patients underwent SLT, and 33 had BLT. Maintenance immunosuppression medications consisted of cyclosporine, azathioprine, and prednisone. RESULTS: Perioperative complications were as follows: seven of 33 patients bled after BLT, and two of 57 bled after SLT. Bronchial complications were found in six of 66 (9%) BLT anastomoses and eight of 57 (14%) SLT anastomoses. Nine operative deaths occurred in SLT patients: six from allograft failure, one from infection, one from intrapulmonary hemorrhage, and one from bronchial dehiscence. Only two patients died in the perioperative period after BLT and that was of infection. Three late deaths occurred after BLT, all as a result of infection; 13 recipients died late after SLT: five of infection, four patients from lymphoma, two of pancreatitis, one of tension pneumothorax, and one of pulmonary embolism. For the entire patient population the actuarial 1- and 2-year survival rates were 72% and 68%, respectively. One-year survival rates were significantly better for patients undergoing lung transplantation for obstructive and nonrestrictive lung diseases than those of patients undergoing lung transplantation for vascular or restrictive pulmonary disease. Recipients of BLT had a trend toward better survival than recipients of SLT. Lung function 6 months after transplantation measured by forced expiratory volume in 1 second was significantly better in BLT than SLT, 71% of predicted versus 54%. CONCLUSIONS: Patients who undergo BLT have significantly better postoperative pulmonary function than those who undergo SLT. On the basis of the study there was a trend toward better survival with BLT.

Adolescent↗
PubMed1993

Evaluation of a low molecular weight heparin as an anticoagulant in a model of cardiopulmonary bypass surgery.

Heparin, the classically used anticoagulant in cardiopulmonary bypass surgery, has several disadvantages such that alternate anticoagulants are being sought. Previous reports have described questionable safety with the clinical use of low molecular weight (LMW) heparin in cardiac surgery. The dog cardiopulmonary bypass model described herein may provide a useful means to study the pharmacology of new drugs prior to clinical use. Dogs were given a single loading dose of 250 USP units/kg (1.66 mg/kg) of unfractionated heparin (control) or 250 anti-factor Xa units/kg (2.3 mg/kg) LMW heparin and placed on bypass for 60 minutes. Prior to, during, and following bypass blood samples were taken to measure coagulation and hematological parameters. The dogs remained anesthetized for 150 minutes post-bypass. Post-operative blood loss and fibrin deposition in the arterial line filters were measured. Our findings showed there was no significant blood loss (heparin 452 +/- 67 gms; LMW heparin 289 +/- 82 gms) and no significant fibrin deposition (heparin 22 +/- 3 gms; LMW heparin 28 +/- 7 gms) with the LMW heparin. These findings suggest that this LMW heparin should be safe and effective at the studied bolus dose as an anticoagulant for use in cardiopulmonary bypass surgery, and that protamine should be used to reverse the anticoagulant response after surgery.

Animals↗
PubMed1993

Infective aortic endocarditis after percutaneous balloon aortic valvuloplasty.

Infective aortic endocarditis developed in an elderly patient after a percutaneous balloon aortic valvuloplasty. The transesophageal echocardiogram demonstrated a perivalvular abscess. The patient underwent surgical replacement of the infected valve, but later succumbed to renal failure. The development of infective aortic endocarditis should be recognized as a potentially fatal complication of percutaneous balloon aortic valvuloplasty. The important measures in preventing bacteremia during percutaneous balloon aortic valvuloplasty and the appropriate role of operation are discussed.

Aged↗