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Biomedical subjects

R R Lower

Publications and source records attributed to R R Lower.

At least 19 recordsLinked to original sources
PubMed1990

Management and long-term followup of outpatient care in the cardiac transplant recipient.

Successful long-term management of the cardiac transplant patient requires the concerted effort of the patient, the cardiac transplant team, and the primary care physician. The long-term management of these patients will continue to evolve as new immunosuppressive agents are used and new methods of surveillance for rejection are found. The long-term management is indeed one of the most exciting parts of the care of the transplant patient, especially when all those involved can watch the patient enter into a normal lifestyle.

Aftercare↗
PubMed1990

Accelerated coronary atherosclerosis in cardiac transplantation.

The implications of this new aggressive form of coronary disease for the transplant population are obvious. It appears that for the majority of transplant patients we have simply bought some time. We have given them a temporary respite from congestive failure and cardiomyopathy while they surmount the daily challenges imposed by immunosuppression. Clearly, this issue now looms as a major stumbling block toward improving long-term survival. It is no longer enough to simply perform the procedure and submit the patient to the rigors of transplantation, only to obtain 50 percent 5-year survival. We must pay particular attention to the patient postoperatively and make those modifications necessary to improve the individual's risk profile. Moreover, we must continue to concentrate our research efforts on interventions in accelerated coronary disease.

Coronary Disease↗
PubMed1989

Orthotopic cardiac transplantation: evaluation with CT.

As cardiac transplantation has become widely available, computed tomography (CT) of the chest has played a useful role in the examination of patients after heart transplantation. To determine anatomic features related to the procedure, the authors evaluated 59 scans in 46 patients who had undergone orthotopic cardiac transplantation. Aortic anastomosis (seen in 98% of scans) and altered spacing between the great vessels (83%) proved to be the most common and most reliable findings. Other features including atrial anastomosis, high main pulmonary artery segment, remnant superior vena cava, and cardiac reorientation were also seen. Accurate interpretation of adenopathy, mediastinal abscess, and pericardial effusion will be enhanced in these patients through a better understanding of the cardiovascular-pericardial complex, which is afforded by CT.

Anastomosis, Surgical↗
PubMed1988

Homograft replacement of single aortic valve cusps: 22 years follow-up.

Single aortic valve cusp replacement with fresh aortic homografts were performed in four patients from November 1966 to April 1970. All had preoperative aortic insufficiency due to destruction of a single cusp, with the remaining two cusps structurally and functionally intact. Replacement was performed using the noncoronary cusp from fresh aortic valve homografts. Patient one had homograft cusp replacement of the left coronary cusp at age 13 due to bacterial endocarditis. She recently underwent mitral valve replacement; study and inspection of the aortic valve showed it to be structurally and functionally intact 22 years following homograft cusp replacement. Patient two sustained a gunshot wound perforating his right coronary cusp. He underwent single cusp replacement in January 1967. Currently, he is asymptomatic and has been without evidence of significant aortic valve dysfunction for the past 21 years. Patient three had destruction of the noncoronary cusp due to endocarditis and had homograft cusp replacement in October 1967. Four and a half years later he developed recurrent endocarditis, presented with severe congestive heart failure due to aortic insufficiency, and died. Patient four had bacterial endocarditis affecting the right coronary cusp and had replacement in April 1970. In February 1980, he underwent aortic valve replacement for aortic stenosis. Inspection revealed calcification of the other two cusps with the homograft cusp structurally normal. In summary, follow-up of homograft replacement of single aortic valve cusps from 4 1/2 to 22 years, shows it to be a durable and feasible alternative to prosthetic valve replacement.

Adolescent↗
PubMed1988

Nonpenetrating vascular injury to the subclavian artery.

Blunt subclavian artery injury has been uncommonly reported in the literature. Recent encounter with three such injuries prompted us to review our experience over the past 10 years uncovering only one additional case. These four cases and a review of pertinent literature form the basis for this article. Key clinical issues include a high index of suspicion in patients sustaining major blunt deceleration and rotational or direct injuries to the neck, thorax, and/or upper extremities. Prompt diagnosis remains obscured by the presence of severe associated injuries, the treatment of which requires prioritization. Arteriography is invaluable to elucidate injury because prompt vascular control is dictated by various approaches depending on the location. Expeditious surgical repair is indicated to prevent complications of hemorrhage, pseudoaneurysm, thromboembolism, and/or arteriovenous fistula. Long-term results appear to be good with major morbidity related to associated neurologic, soft tissue, and bony injuries.

Adolescent↗
PubMed1987

Urinary thromboxane excretion in cardiac allograft rejection in immunosuppressed rats.

Increased urinary excretion of immunoreactive thromboxane B2 (iTxB2) was found to have a high predictive value, with high sensitivity as an indicator of cardiac allograft rejection in both the immunosuppressed and nonimmunosuppressed rat. In the animals receiving an allograft, urinary iTxB2 excretion significantly increased prior to the onset of rejection, remained elevated, and returned to basal values following completion of the episode. Urinary iTxB2 remained at baseline values in the control animals. The association between rejection and iTxB2 excretion was preserved regardless of the presence or nature of immunosuppression. Urinary iTxB2 excretion increased significantly prior to the reduction of graft beat or histological evidence of rejection. Evaluation of urinary iTxB2 monitoring as a noninvasive indicator for surveillance of clinical cardiac allograft rejection appears to be warranted.

Animals↗
PubMed1987

Pretransplant transfusions in cardiac allograft recipients.

The role of pretransplant transfusion in cardiac allograft recipients was determined retrospectively in 68 patients. Three groups were studied: group 1 (n = 29) received no pretransplant transfusion, group 2 (n = 15) received transfusion over one year prior to transplantation, and Group 3 (n = 24) received 5 or 10 50-100 ml units of random donor red blood cells or buffy coat 2-4 weeks prior to transplantation. Data were analyzed for survival, number of rejection episodes, and number of infections. Immunosuppression included azathioprine, prednisone, and antithymocyte globulin. Survival in transfused patients (groups 2 and 3) was 68% and 51% at 1 and 5 years, respectively, while in the nontransfused population (group 1) it was 35% and 16%. The incidence of rejection episodes per year of survival was similar in the three groups (group 1: 1.3, group 2: 1.1, group 3: 1.3; P greater than 0.05). The number of infections per year of survival were greater in the transfused patients but this did not achieve statistical significance (group 1: 1.0, group 2: 1.2, group 3: 1.7; P greater than 0.05). Thus, we conclude that cardiac transplant recipients who have received blood transfusions prior to transplantation may have enhanced survival over patients who have not received preoperative transfusions.

Blood Transfusion↗
PubMed1986

T-lymphocyte analysis in cardiac allograft recipients treated with cyclosporine.

To assess the usefulness of circulating T-lymphocyte analysis in cardiac transplantation, T helper (Th) and T suppressor-cytotoxic (Ts-c) subsets were serially monitored in 33 cardiac allograft recipients treated with cyclosporine. The short-term prognosis of their 47 treated rejection episodes were retrospectively correlated with the changes in T-cell subpopulations. The data indicate three main findings. Reversed Th to Ts-c ratio (less than 1) was associated with a reduced incidence of rejection onset and a benign clinical course after treatment for rejection. Reversed Th:Ts-c ratio caused by antirejection therapy was associated with less chance of recurrence during the rest of hospitalization, regardless of the mode of therapy and irrespective of whether the rejection was primary or recurrent. These changes were mainly mediated by a reduction in T helper cells rather than changes in the T suppressor-cytotoxic subset or total T cells. Titration of antirejection therapy based on these T-cell dynamics may reduce either overtreatment or undertreatment. A prospective randomized study seems warranted to evaluate this approach as an alternative to a predetermined antirejection protocol.

Cyclosporins↗
PubMed1986

Afferent reinnervation of the autotransplanted heart in dogs.

Patients have been observed with a chest pain syndrome after cardiac transplantation. For this pain to be cardiac in origin the afferent nerves carrying sensory information from the heart would have to reinnervate the heart. A previous study in dogs indicated that afferent reinnervation is uncommon during the first 2 years after transplantation. The purpose of this study was to determine whether afferent reinnervation of the heart occurs in the long term. The decreases in arterial pressure and renal nerve activity resulting from chemical stimulation of left ventricular sensory receptors with vagal afferents with cryptenamine (veratrum alkaloid) were assessed in three dogs 8 to 12 years and in four dogs 6 to 8 weeks after cardiac autotransplantation and in six sham-operated dogs (thoracotomy-pericardiotomy 6 to 8 weeks before study). Responses of renal nerve activity to physiologic stimulation of cardiac receptors by volume expansion were also determined. Left ventricular cryptenamine inhibited renal nerve activity by 72 +/- 8% in dogs with long-term and by 10 +/- 6% in dogs with short-term autotransplantation and by 92 +/- 5% in sham-operated dogs. Decreases in mean arterial pressure in these groups were 34 +/- 4, 11 +/- 3 and 67 +/- 16 mm Hg, respectively. Volume expansion inhibited renal nerve activity in long-term autotransplant (43%) and sham-operated (48%) groups but less in the short-term transplant group (33%) for comparable increases in cardiac filling pressure. It is concluded that in dogs there is extensive afferent reinnervation of the long-term autotransplanted heart that results in relatively normal cardiopulmonary baroreflex responses to volume expansion.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1986

Myocardial norepinephrine, epinephrine and dopamine concentrations after cardiac autotransplantation in dogs.

Myocardial norepinephrine is markedly reduced after cardiac transplantation because of interruption of postganglionic cardiac sympathetic nerves. There are also substantial stores of dopamine in the myocardium, but the influence of cardiac denervation on dopamine remains unknown. The effect of cardiac transplantation was determined and, thus, the effect of denervation on myocardial norepinephrine, dopamine and epinephrine. Myocardial catecholamines were measured with high-performance liquid chromatography with electrochemical detection in five dogs 6 to 8 weeks and in four dogs 8 to 12 years after cardiac autotransplantation and in six sham-operated dogs with intact cardiac innervation. Norepinephrine, dopamine and epinephrine levels were determined from samples obtained from the right and left atria and ventricles. Samples from the left ventricular apex and base were analyzed separately. There was a striking depletion of norepinephrine in all cardiac chambers after short-term autotransplantation. The norepinephrine content of the left atrium in sham-operated dogs (1,659 +/- 219 ng/g) was significantly higher than that of dogs with long-term autotransplanted hearts (754 +/- 372 ng/g). Sham-operated dogs and dogs with long-term autotransplanted hearts had statistically significant (p less than 0.05) differences in norepinephrine content in the left ventricular apex (480 +/- 197 versus 294 +/- 198 ng/g), left ventricular base (876 +/- 2204 versus 654 +/- 156 ng/g) and right ventricle (766 +/- 133 versus 247 +/- 29 ng/g). In contrast to norepinephrine, dopamine concentrations were relatively preserved in the short-term group despite the virtual depletion of myocardial norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Oxide↗
PubMed1986

Heart and unilateral lung transplantation in the dog.

A technique is presented for transplantation of the heart and left lung en bloc in the dog. In contrast to the erratic respiratory pattern that occurs in subprimate animals after total cardiopulmonary denervation, preservation of innervation to the native right lung results in a normal respiratory pattern in the dog and has allowed survival of one animal for 68 days. This model is proposed as potentially suitable for physiologic and immunologic studies of cardiopulmonary transplantation in the dog.

Animals↗