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Biomedical subjects

R H Johnston

Publications and source records attributed to R H Johnston.

13 recordsLinked to original sources
PubMed2000

Subretinal fibrosis in patients with Vogt-Koyanagi-Harada disease.

OBJECTIVE: To describe subretinal fibrosis as a long-term complication of Vogt-Koyanagi-Harada (VKH) disease. DESIGN: Retrospective, clinic-based, cross-sectional study and clinical correlation. PARTICIPANTS: Ten patients with VKH disease and subretinal fibrosis were seen at two uveitis referral centers between 1977 and 1997. INTERVENTION: A review of the historical, clinical, and fluorescein angiographic features was performed. MAIN OUTCOME MEASURES: The prevalence, demographic and clinical features, and time to development of subretinal fibrosis were summarized. RESULTS: Subretinal fibrosis occurred in 20 eyes of 10 patients with VKH disease, an overall prevalence of 8% between the two institutions. Patient age ranged from 16 years to 48 years, with a median of 34.5 years. Five patients were Hispanic, one was mixed Hispanic and American Indian, three were Asian or mixed Asian and Caucasian, and one was African-American. Eight of the 10 patients were men. All patients were in the chronic, recurrent phase of their disease when they had subretinal fibrosis develop, and all patients had recurrent episodes of posterior uveitis. Presenting vision ranged from 20/20 to light perception, with a median acuity of 20/200. All patients were initially treated with oral and topical corticosteroids. Four patients required additional noncorticosteroid immunosuppressive therapy. Time from diagnosis of VKH disease to development of subretinal fibrosis ranged from zero (fibrosis present at time of diagnosis) to 27 years, with a median time of 10 months. The median time from diagnosis of VKH to development of subretinal fibrosis in Hispanic patients was 6.5 months, whereas in non-Hispanic patients it was 6.5 years. Final vision ranged from 20/25 to light perception, with a median acuity of 20/60. Seven of 20 eyes had a final visual acuity of 20/40 or better, and seven eyes saw 20/200 or worse. Five of the eyes with 20/200 or worse vision had fibrosis involving the fovea. CONCLUSIONS: Subretinal fibrosis occurs in a sizeable proportion of patients with VKH disease and may contribute to permanent loss of vision.

Adolescent↗
PubMed1999

Clinical study of combined penetrating keratoplasty, pars plana vitrectomy with temporary keratoprosthesis, and pars plana seton implant.

PURPOSE: To assess the effectiveness of a combined procedure (pars plana vitrectomy with temporary keratoprosthesis, penetrating keratoplasty, and pars plana seton implant) in preserving vision and controlling intraocular pressure (IOP). METHODS: We reviewed the course of visual acuity, IOP, graft clarity, retinal status, and complications in 18 patients who underwent the above procedure during one operating sitting. RESULTS: Preoperative diagnoses were varied. The majority of patients had pseudophakic bullous keratopathy and failed corneal transplants with glaucoma. Preoperative mean visual acuity was hand motions. Preoperative mean IOP was 27+/-13 mm Hg. Initially, all patients had attached retina. With a mean follow-up of 17+/-9 months, six patients had improved vision greater than 2 lines and 10 had unchanged vision. Only two patients lost vision greater than 2 lines. The final average IOP was 16+/-6 mm Hg and only one eye had a pressure above 22 mm Hg. Three eyes were classified as complete failures; two of the three became phthisical. Two patients developed rhegmatogenous detachments requiring further surgery. CONCLUSION: The combined procedure offers reasonable improvement in vision, good pressure control, and a tolerable number of complications. It is a useful procedure in eyes that probably would not have been treatable otherwise.

Adolescent↗
PubMed1997

Endothelial cell analysis of corneas from donor eyes with an intraocular lens: a comparative study.

PURPOSE: Many eyes are received from patients who have undergone cataract surgery. Few data document the endothelial cell characteristics in these donor eyes, which have previously been disqualified for transplantation. We compared the endothelial characteristics of the corneas from eyes with intraocular lenses (IOLs) with a group of matching controls. METHODS: The corneal endothelial characteristics, including cell density, polymegethism, and pleomorphism, were prospectively obtained in 15 corneas from eyes with IOL implants and compared with 17 phakic control eyes. RESULTS: The mean cell densities (+/-SD) were 2,495 +/- 438 cells/mm2 for the eyes with implants and 2,576 +/- 264 cells/mm2 for the controls. The mean coefficient of variation was 0.307 +/- 0.04 and 0.323 +/- 0.04 for IOL and control group, respectively. No significant difference was found between the two groups (t test, power = 0.97 in detecting a mean difference of 20%). CONCLUSION: Many eyes with IOLs have endothelial cell densities comparable to those of phakic eyes. A decision to use specific corneas should be made individually based on endothelial cell analysis. Previous ocular surgery may not disqualify a corneal donor.

Aged↗
PubMed1994

Transcervical gunshot injuries.

Gunshot injuries across the cervical midline are not addressed in existing trauma algorithms. A retrospective study of 41 patients with transcervical gunshot wounds was undertaken to delineate injury patterns and management principles. Thirty-four of the 41 patients (83%) sustained 52 injuries to major cervical structures. Vascular (22 injuries) and upper airway (13 injuries) structures were most commonly involved. This resulted in presentation with life-threatening problems in 16 patients (39%). The in-hospital mortality was 10%. In 30 of the 36 neck explorations (83%), the findings were positive for injuries to cervical structures. Sixteen bilateral explorations were performed; in each case, cervical injury was observed on at least one side of the neck. These results indicate that transcervical injuries are excellent markers of associated visceral injury. Therefore, a policy of mandatory neck exploration and a particularly "low threshold" for bilateral exploration are the key to managing these injuries.

Adolescent↗
PubMed1993

Innominate artery trauma: a thirty-year experience.

PURPOSE: Injury to the innominate artery may represent a zone I cervical, thoracic outlet, or intrathoracic vascular injury and poses diagnostic, exposure, and management problems for the general, vascular, and thoracic surgeon. This complex injury often becomes a new learning experience with each infrequent encounter. METHODS: Between 1960 and 1992 43 patients with innominate artery injuries were treated. Penetrating injuries were from gunshot wounds in 25, stab wounds in 7, and shotgun wounds in 2 patients. Blunt injuries accounted for seven of the patients. In 28 patients there were multiple injuries, including multiple vascular injuries. Median sternotomy was used in all planned operations in the later part of the study, and bilateral transsternal anterolateral thoracotomy was used in patients undergoing urgent or emergency center thoracotomy. RESULTS: Blunt injury resulted in tears near the aortic arch with intimal disruption. Bypass grafting without hypothermia, shunts, or systemic heparinization is now used in all patients. Thirty-two patients survived to leave the hospital with no new complications related to the procedure. Postoperative neurologic complications were associated with preexisting neurologic deficits. CONCLUSIONS: Patients with innominate artery injury and stable vital signs can usually be transported without difficulty and treated without complex perioperative adjuncts. These patients can undergo revascularization with simple vascular surgical techniques and should expect an uncomplicated postoperative course unless there has been associated central nervous system injury or related injuries leading to systemic infection. Synthetic conduits have been used with success and have not required systemic heparinization or complex temporary shunting.

Adolescent↗
PubMed1993

Coronary artery endarterectomy: a method of myocardial preservation.

The lack of acceptable coronary arteries for grafting often causes the cardiac surgeon considerable problems in treating patients with severe coronary artery disease. By combining the standard approach of coronary bypass surgery with coronary endarterectomy and with retrograde coronary sinus cardioplegia perfusion, we can achieve a longer ischemic period and can flush the debris from the coronary arteries in a retrograde fashion. Using this approach, we managed 72 patients with near inoperable coronary artery disease. One third of these patients required endarterectomy of more than one vessel. A higher than expected number of patients had diabetes mellitus. The left coronary artery system required endarterectomy in almost 60% of patients, much higher than percentages reported in other series of patients. The mortality rate in our patients who underwent the left system endarterectomy was 5.7%. Endarterectomy must be considered an adjunct in the management of high-risk patients with severe coronary artery disease.

Aged↗
PubMed1986

Pancreatic pseudocyst of the mediastinum.

A patient with pancreatic pseudocyst of the mediastinum is presented. Weight loss, chest or abdominal pain, and dyspnea are the most frequent symptoms of mediastinal pseudocyst. Chest roentgenogram frequently demonstrates a posterior mediastinal mass, and esophagogram always shows esophageal displacement. The diagnosis is confirmed by computerized axial tomography of the chest and abdomen. Cyst-gastrostomy is the operation of choice for this condition.

Aged↗
PubMed1985

Mersilene ribbon closure of the median sternotomy: an improvement over wire closure.

With the increased utilization of median sternotomy in thoracic surgery, some difficulties have arisen with closure of the sternum. This article presents a simple, easy-to-perform method of sternal closure utilizing reinforcement of the sternal halves with a material that is less likely to cut through the sternum and that is readily available.

Cardiac Surgical Procedures↗
PubMed1985

Implantation of pericardial substitutes.

Pericardial substitutes have been shown to decrease the formation of pericardial adhesions. For a pericardial substitute to be properly implanted, it must lie over the heart smoothly without buckling and prevent the accumulation of blood under its surface. The technique we describe prevents buckling of the pericardial substitute and consequently reduces the formation of pericardial adhesions.

Humans↗
PubMed1984

The Ionescu-Shiley valve: a solution for the small aortic root.

Valve replacement in patients with a small aortic anulus can cause difficult technical problems or leave the patient with a significant residual transvalvular gradient. Between August, 1977, and June, 1983, 35 patients with a small aortic root (21 mm or less) underwent aortic valve replacement with Ionescu-Shiley pericardial xenograft valves. They ranged in age from 29 to 76 years (mean 52.8 years) and in weight from 64 to 91 kg (mean 76.3 +/- 3.6 kg). Preoperatively, 26 patients were in New York Heart Association Functional Class III-IV. The valve sizes used were 17 mm in three cases, 19 mm in 16 cases, and 21 mm in 16 cases. There were four hospital deaths (11.4%) resulting from sepsis or low cardiac output. There were no late deaths. Cumulative duration of follow-up was 819.4 patient-months. Twenty-four (78%) of the 31 surviving patients are asymptomatic. Up to the time of review, there have been no episodes of thromboembolism, infective endocarditis, perivalvular leak, valve thrombosis, or primary tissue valve failure. Fifteen patients were hemodynamically evaluated 2 to 47 months (mean 14.3 months) after operation. The average resting transvalvular gradients for 19 and 21 mm valves were 15.1 and 10.8 mm Hg, respectively. Our experience suggests that the Ionescu-Shiley pericardial xenograft valve is a valid alternative in the surgical treatment of patients with a small aortic root.

Adult↗
PubMed1980

A biotelemetry system for monitoring heart rates in unrestrained ungulates.

An EKG telemetry system has been designed for use on free-living ungulates. An FM transmitter with a battery life of 2 +/-0.5 months and a range of 2-6 km is mounted on the back of the animal by means of an adjustable harness. The EKG signal is detected by subdermal electrodes overlying the sternum and transmitted to an FM receiver equipped with a frequency down-converter. The output of the receiver is the modulated audio carrier which is recorded on magnetic tape. The EKG waveform is recovered from the tape-recorded signal using an FM demodulator connected to a strip chart recorder.

Animal Population Groups↗