Biomedical subjects

K R Hess

Publications and source records attributed to K R Hess.

97 records · Page 6Linked to original sources

PubMed1988

Aortic dissection and dissecting aortic aneurysms.

Operation was employed in the treatment of 546 patients for complications of aortic dissection during the 32-year period of 1956-1988. Current concepts and operative techniques evolved during this period. Fortunately, about half the patients were treated during the latter 4 years, as modern therapy became standardized. The cumulative survival rate was 86% for all patients and 94% for those treated during recent years. Pathologic processes and requirements of operation became clearer by treating 174 patients who had had 198 previous operations by the time of referral. Reoperation was required for complications of operations now considered outdated, heart operations in patients with ascending aortic dilatation, and progressive dilatation of residual segments of the aorta. The 546 patients were followed, and a total of 838 operations were finally employed, resulting in total aortic replacement in 18, near total replacement in 41, entire thoracic aorta in 22, near total thoracic aorta in 33, and the entire thoracoabdominal aorta in 148 patients. Long-term survival in 439 patients after final operation was 66% and 44% at 5 and 10 years, respectively, despite the fact that the median age at first admission was 59. Operative treatment appears to be well-established for this disease.

Adolescent↗

PubMed1988

The impact of distal aortic perfusion and somatosensory evoked potential monitoring on prevention of paraplegia after aortic aneurysm operation.

Temporary distal aortic perfusion and somatosensory evoked potential monitoring were attempted prospectively in 198 patients to prevent neurologic complications from occurring after operation for descending thoracic and thoracoabdominal aortic aneurysm. These 198 patients were divided into two groups. Group 1 consisted of 99 (50%) patients in whom adequate (60 mm Hg) distal bypass was achieved and combined with somatosensory evoked potential monitoring. Group 2 consisted of 99 (50%) in whom this could not be achieved. Of the latter, four patients were excluded because of operative death in one and preexisting neurologic deficits in three. The rates of early and delayed neurologic complications were 8% and 12%, respectively, in the former and 7% and 8%, respectively, in the latter. Using the logistic regression method of statistical analysis, adjusting for the difference in patient mix, we found no statistical difference in the incidence of neurologic complications in the two groups. The incidence of false negative somatosensory evoked potential response was 13% and false positive response 67%. Localization of critical spinal arteries for reattachment was not possible. Thus, the method had no significant impact upon the prevention of neurologic deficits, which varied from mild or transient to severe and which either occurred during the operation or were delayed from 12 hours to 21 days.

Aorta, Thoracic↗

PubMed1986

Thoracoabdominal aortic aneurysms: preoperative and intraoperative factors determining immediate and long-term results of operations in 605 patients.

Graft inclusion and vessel reattachment to openings made in the graft were employed in the treatment of 605 patients with thoracoabdominal aortic aneurysms. These patients were divided into four groups on the basis of the extent of aneurysm. Group I consisted of those patients with involvement of most of the descending thoracic and upper abdominal aorta; group II involved most of the descending thoracic aorta and most or all of the abdominal aorta; group III involved the distal descending thoracic aorta and varying segments of abdominal aorta; and group IV involved most or all of the abdominal aorta including the segment from which the visceral vessels arose. The cause of aneurysm formation was medial degenerative disease in 80%, and dissection in 17%; other causes were responsible in the remaining 3%. The median age was 65 years and associated diseases including aneurysms involving other segments, atherosclerotic occlusive disease, heart disease, chronic obstructive pulmonary disease (COPD), hypertension, and renal insufficiency were frequent. The aneurysm was symptomatic in 70% of cases and rupture had occurred in 4% of cases. There were 54 (8.9%) early (30-day) deaths and 151 late deaths; 400 (66%) patients were still alive 3 months to 20 years after operation, including 60% at 5 years. Statistically significant pre- and intraoperative variables by univariate analysis that were predictive of increased risk of early death were advancing age, associated diseases that included COPD, renal artery occlusive disease, atherosclerotic heart disease, renal insufficiency, and long aortic clamp time. Three of these (age, clamp time, and the presence of COPD) retained significance by multivariate analysis. Variables predictive of risk of late death were age, dissection, extent of aneurysm, rupture, heart disease, cerebrovascular disease, COPD, hypertension, and poor renal function. Age, rupture, renal dysfunction, extent of aneurysm, and dissection retained their significance by multivariate analysis. Variables predictive of neurologic disturbances of the lower extremities included rupture, reattachment of intercostal and lumbar arteries, clamp time, dissection, extent and age. Rupture, reattachment of vessels, dissection, and extent of aneurysm retained significance by multivariate analysis. Thus, the risk of this complication was greatest in patients with extensive lesions (group II) with aortic dissection. The greatest risk of renal failure after operation that required dialysis was in patients who had impaired renal function before operation. Methods employed did not prevent these complications.

Adolescent↗

PubMed1986

Pacemaker follow-up: its role in the detection and correction of pacemaker system malfunction.

The goal of pacemaker follow-up is not only to detect battery depletion but also to detect all malfunctions of the pacing system and, when possible, to correct such problems using programming. During one year, we discovered 61 such malfunctions in a clinic of 1065 patients (5.7%). These were more frequent in the first year (7.7%) than in the third to fifth years of follow-up (range 3.1-4.8%). The incidence rose again in the sixth and subsequent years (7-7.7%). Despite a significant occurrence of malfunctions (5.2%) among multiprogrammable pacemakers, the necessity for operative intervention for their correction was low (1.2%). Sensing problems were the most common (57%) and the most likely to be corrected by reprogramming (85%); problems involving loss of capture were less likely to be corrected by programming (38.5%). Battery depletion accounted for only 18% of malfunctions, occurring earliest in the forty-third month of follow-up. Pulse generator longevity of those devices reaching end of battery life during the study period was 68.6 +/- 16.7 months (mean + SD). We conclude that specialized pacemaker follow-up continues to be necessary despite improved pulse generator reliability and longevity. Indeed, with reprogramming, it presently plays an even more important role than in the past. Follow-up should be oriented not only to the detection of battery depletion but also toward a comprehensive surveillance of pacemaker system function.

Equipment Failure↗

PubMedDate not supplied

Prognostic factors in resectable pancreatic cancer: p53 and bcl-2.

The p53 tumor suppressor gene and the Bcl-2 proto-oncogene regulate cell cycle progression and apoptosis. We evaluated the expression of these molecular markers with standard pathologic prognostic variables in patients who received multimodality therapy for resectable adenocarcinoma of the pancreas to study the effect of p53 and Bcl-2 on survival duration. Immunohistochemical staining of archival material was performed to determine levels of expression of p53 and Bcl-2 proteins in 70 patients with adenocarcinoma of pancreatic origin. All patients underwent a potentially curative pancreaticoduodenectomy and standardized pathologic analysis of resected specimens. Potential pathologic and molecular prognostic variables were assessed for their effect on survival duration. Nuclear staining for p53 was observed in 33 (47%) of 70 specimens. Immunostaining for Bcl-2 was observed in 23 specimens (33%). A trend toward improved survival duration was seen in patients whose tumors stained positive for either p53 or Bcl-2. Negative staining for both markers predicted short survival (P = 0.01). By univariate and multivariate analyses, no single pathologic factor was associated with survival duration. Immunohistochemical staging using both p53 and Bcl-2 significantly predicted survival duration by univariate and multivariate analysis; patients whose tumors stained positively for p53 and/or overexpressed Bcl-2 had a significantly longer survival than those whose tumors stained negative for both proteins.

Adenocarcinoma↗

PubMedDate not supplied

A reevaluation of the association between instrument delivery and epidural analgesia.

BACKGROUND AND OBJECTIVES: Over 100 papers in the medical literature suggest pro or con that epidural analgesia is associated with an increase in the incidence of instrument delivery. This two-component study was performed to evaluate the influence of epidural labor analgesia on the incidence of instrument delivery. METHODS: Component 1 was a retrospective analysis of the medical records of 14,804 mothers having a vaginal delivery before and after implementation of an active epidural service. Component 2 was a case control study designed to determine factors, in addition to epidural analgesia, associated with an increase in instrument delivery. In component 2 11 factors describing maternal, fetal, anesthetic, and obstetric factors were analyzed for each of 609 consecutive patients having an instrument delivery and 246 controls having a spontaneous vaginal delivery. RESULTS: In component 1, despite a tenfold increase in the use of epidural analgesia, there was a similar association between epidural use and instrument delivery in both time periods. Additionally, the epidural-forceps association was twice as strong for parous patients as for nulliparous patients (odds-ratios 9.74 and 4.52, respectively). In component 2, five factors were significantly (P > .0001) associated with instrument delivery conclusions. CONCLUSIONS: While epidural analgesia was one factor, the others were gestational age > 41 weeks, a second stage of labor > 2 hours, an occiput posterior or transverse fetal position, and previous cesarean section. These four factors are individually and independently associated with an increase in the incidence of instrument delivery independent of epidural use.

Adolescent↗

PubMedDate not supplied

Anatomic constraints for a total artificial heart in orthotopic heart transplant recipients.

The anatomic constraints and design parameters for a heart prosthesis have not yet been defined in heart transplant recipients (i.e., the population most eligible for total artificial heart implantation). The parameters regarding anatomic constraints were measured in 26 consecutive patients undergoing orthotopic heart transplantation (median body surface area 1.9 m2) after cardiectomy. A full-sized contour model of the cylindric total artificial heart (diameter 97 mm; width 81 mm) was inserted into the pericardial cavity to decide the pump configuration and to verify its fit. The dimensions of this model were based on the miniature electromechanical total artificial heart that is currently under development. Fit was found to be adequate in most of the cases with no identifiable compression of adjacent vascular structures. The median intraoperative measurements that define pericardial constraints for a heart prosthesis were pericardial length (130 mm), width (160 mm), and depth (140 mm). We also took measurements from the excised hearts, which should provide a useful reference for other prosthetic devices. The current dimensions of our implantable total artificial heart were found acceptable for orthotopic implantation. Length of the pericardium and cardiothoracic ratio were identified as variables related to adequacy of fit.

Adult↗