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Biomedical subjects

B A Reitz

Publications and source records attributed to B A Reitz.

At least 253 records · Page 14Linked to original sources
PubMed1979

Operative treatment of aortic dissections. Experience with 125 patients over a sixteen-year period.

An unselected, consecutive cohort of 125 patients underwent operative repair of acute and chronic aortic dissections with tubular graft interposition over a 16 year span. The absence of remote geographical referral biases and the unselected nature of this series provided a patient population that was representative of the disease process (as assessed heretofore only from autopsy series). Furthermore, this enabled high-risk subsets to be defined by retrospective analysis. Patients were classified according to whether the ascending aorta was involved (type A with involvement, type B without), irrespective of the site of intimal tear, and according to age of the dissection: Fifty-three patients had acute type A (Ac-A), 29 had chronic type A (Ch-A), 20 had acute type B (Ac-B), and 23 had chronic type B (Ch-B) dissections. Fourteen percent (17/125) of the dissections had ruptured. Concomitant aortic valve replacement (AVR) was performed in 11% (6/53) for Ac-A cases and 38% (11/29) of the Ch-A cases. A total of 391 patient-years of follow-up was analyzed; follow-up averaged 4.5 years and extended to 13.7 years. Over-all operative mortality rate was 34% (18/53) for Ac-A, 14% (4/29) for Ch-A, 45% (9/20) for Ac-B, and 22% (5/23) for Ch-B; during the most recent 5 year interval these figures were lower: 27%, 8%, 20%, and 20%, respectively, N = 50. Multiple preoperative variables were found to correlate significantly with both operative death and long-term survival. Operative survivors generally experienced satisfactory functional benefit. Late attrition averaged 8% per year; 61% of all late deaths were related to cardiac or cerebral causes. Over-all actuarial survival (+/- SEM) for the entire cohort was 54% +/- 5% at 5 years and 26% +/- 7% at 10 years; for the 89 patients surviving operation, these figures were 76% +/- 5% and 37% +/- 10%, respectively. No significant differences in long-term survival were evident between the different subgroups. Whether the primary intimal tear had been resected or concomitant AVR had been performed had no statistically significant bearing on operative mortality, functional result, necessity for late reoperation, or late attrition. The long-term "natural" history of surgically treated patients with aortic dissections, as defined in this study, should facilitate comparison with other treatment modalities. Results of the present analysis support immediate operative intervention for patients with Ac-A dissections and probably for those with Ac-B dissections. Additionally, surgical treatment of patients with symptomatic or enlarging Ch-A and Ch-B dissections provides satisfactory rehabilitation and long-term survival. Finally, we re-emphasize our recommendation for simplified classification of aortic dissections, based solely upon the presence or absence of ascending aortic involvement. Pathophysiology and expected biologic behavior pivot on this feature, and appropriate clinical strategy can thereby be defined.

Adult↗
PubMed1978

Tissue valve replacement of prosthetic heart valves for thromboembolism.

Twenty-five patients who had repeated thromboemboli from a prosthetic mitral valve were treated with reoperation using a tissue valve prosthesis. Reoperation was performed an average of 4.0 years after the original valve replacement in 14 men and 11 women, with an average age of 50 (range 35 to 65) years. A stented allograft was used in the first 7 patients and a porcine xenograft in the last 18 patients. There were one hospital death and two late deaths. With the first prosthetic valve there were 66 documented embolic episodes in 101.5 patient years (0.65 embolus/year). Only four embolic episodes in 67.4 patient years (0.059 embolus/year) occurred after tissue valve replacement (P less than 0.001). These results indicate that in patients with recurrent or severe embolization after prosthetic heart valve replacement, rereplacement with a tissue prosthesis can be safely performed and significantly reduces the likelihood that additional embolic episodes will occur.

Adult↗
PubMed1978

Depressant effect of digoxin on atrioventricular conduction in man.

We examined the effect of chronically administered digoxin on atrioventricular (A-V) conduction in nine cardiac transplant recipients. We assessed A-V conduction by measuring the duration from the pacing stimulus to the onset of the QRS complex (S'R interval) and by determining the occurrence of Wenckebach periodicity during rapid atrial pacing. We made measurements during a control period and during a period of digoxin administration of up to 37 days. During the digoxin period, the cycle length at which Wenckebach block occurred was prolonged by 14% of the control value and the S'R interval was significantly prolonged at paced rates of 110 beats per minute and faster. After digoxin was discontinued, the Wenckebach periodicity and S'R interval returned to control values. Atropine and propranolol did not alter digoxin's effect on A-V conduction. We conclude that digoxin exerts a direct (or non-neurally mediated) depressant effect upon A-V conduction in man, although the stress of tachycardia is necessary to demonstrate the effect.

Atrioventricular Node↗
PubMed1978

Current expectations in cardiac transplantation.

Survival after cardiac transplantation has improved significantly over the past 3 1/2 years at our Center as compared to previous experience (Fig. 5). Currently, survival rates for 60 patients who have had heart transplantation since late in 1973 (program year mean survival +/- S.E.) are 66 percent (+/- 6.6 S.E.), 63 percent (+/- 7.0) and 58 percent (+/- 8.2) 1, 2, and 3 years after operation, respectively. In this report the major reasons for this successful trend have been summarized. These consist of transvenous endomyocardial biopsy for diagnosis and management of graft rejection, use of RATG, immunologic monitoring for early detection of impending rejection, and cardiac retransplantation in selected cases. The present expectations for survival and rehabilitation after heart transplantation are fully comparable to the current results of renal transplantation from unrelated donors. These considerations support the inclusion of cardiac transplantation as a realistic therapeutic alternative in the management of patients with advanced heart disease irremediable by standard forms of treatment.

Antilymphocyte Serum↗
PubMed1978

Impact of simultaneous myocardial revascularization on operative risk, functional result, and survival following mitral valve replacement.

A cohort of 282 patients who underwent mitral valve replacement with a xenograft bioprosthesis was strictly segregated according to etiology of mitral dysfunction and analyzed regarding the impact of arteriographic coronary artery disease (CAD) and concomitant coronary artery bypass grafting (CABG) on operative risk, functional result, and survival. CAD was present in 21% of the 122 patients with predominant mitral stenosis (MS) and 59% of the 155 patients with mitral regurgitation (MR); moreover, discordance between the presence of angina and anatomic CAD was found in 27% (33 of 122) of the MS subgroup and 36% (56 of 155) of the MR subgroup. Etiology of the valvular dysfunction was rheumatic in 148 patients, myxomatous degeneration in 83, and ischemic in 32. Within these subgroups, 41 patients (27%), 40 patients (48%), and 32 patients (100%), respectively, had CAD. Of those patients with CAD, 85% of the rheumatic subgroup, 90% of the degenerative subgroup, and 81% of the ischemic subgroup underwent concomitant CABG at the time of valve replacement. Within each subgroup no statistically significant (P greater than 0.05) differences in operative mortality rate, perioperative myocardial infarction rate, incidence of late angina or late infarction, or late actuarial survival were evident when compared on the basis of CAD, and/or CABG, with one exception. The exception was the 10% incidence of perioperative myocardial infarction in the rheumatic subgrohp with coronary disease versus 2% in the rheumatic subgroup without coronary disease (P = 0.05). Within the time constraints of this study (mean follow-up = 2.3 years; maximum follow-up = 5.9 years), these results support simultaneous MVR and CABG when hemodynamically appreciable CAD is found. Moreover, the overall 43% incidence of arteriographic CAD warrants routine coronary angiography in most adults undergoing preoperative catheterization for mitral valvular disease.

Adolescent↗
PubMed1977

Abdominal aortic aneurysmectomy in long-term cardiac transplant survivors.

Two thirds of the 114 patients undergoing heart transplantation at Stanford (Calif) Medical Center have had atherosclerotic cardiac disease. Two of these patients have been found in the late posttransplant period to have symptomatic abdominal aortic aneurysms requiring resection. We present the clinical course and successful operative treatment of these two patients, with emphasis on the prophylaxis of infection and maintenance of hemodynamic, metabolic, and immune stability. Close surveillance of the long-term cardiac transplant survivor should be directed towards other manifestations of atheroscleortic disease.

Aorta, Abdominal↗
PubMed1977

Effects of dipyridamol and methylprednisolone on intimal thickening in vein grafts.

Fibrous intimal proliferation severe enough to produce occlusion has been observed in vein segments used for aorta-coronary bypass grafts. In an attempt to improve graft patency and decrease intimal fibrous thickening, animals with vein grafts were treated with dipyridamole or methylprednisolone for 8 to 12 weeks. Femoral vein segments were used to bypass the femoral artery in 36 dogs. Thirty-four of these grafts were patent at 8 weeks, with no statistically significant differences between control and drug treatment groups. Intimal thickness measurements were taken at three different points along the graft: proximal (upstream end), middle,and distal (downstream end). Dogs treated with methylprednisolone had significantly less intimal thickening (214 versus 125 mu, p less than 0.05) than did control animals in the middle of the veins but there was no difference in thickness measurements at the proximal and distal ends. Dipyridamole-treated animals did not differ from control dogs. Although these data show decreasing intimal thickening in the middle of grafts with methylprednisolone therapy, the intimal thickness was still considerably greater than normal. The lack of response near the anastomotic sites suggests that clinical application of either agent to improve long-term patency is unwarranted.

Animals↗
PubMed1976

Human heart transplantation: current status.

The overall survival rate for 97 heart transplant recipients operated on from 1968 to 1975 has been 49% at one year and 23% at five years. Progressive improvement in one-year survival has been achieved, from 22% in 1968 to 62% in 1974. The major factors responsible for increasing survival are better understanding and management of acute and chronic rejection. Current results suggest that heart transplantation deserves wider application in the treatment of selected patients with end-stage myocardial insufficiency.

Acute Disease↗
PubMed1975

Laboratory evaluation of intraoperative myocardial protection. The need for appropriate animal models.

The investigative laboratory is the appropriate place to evaluate methods of intraoperative myocardial protection. It is becoming apparent that diseased myocardium is more susceptible to intraoperative injury than is normal heart muscle, and so animal models that simulate human cardiac disease states such as chronic left ventricular hypertrophy should be used to assess various techniques. Long-term studies on animals surviving operation are necessary in order to evaluate the chronic effects of various methods of protection.

Animals↗
PubMed1975

Topical hypothermic protection of the myocardium.

Profound topical hypothermia for intraoperative protection of the heart has been employed as an alternative to selective coronary perfusion with excellent clinical results. Based upon observations that hypothermia decreases cellular metabolism and prevents cellular damage from anoxia, topical hypothermia has been employed to provide protection for anoxic intervals exceeding 60 minutes. Additional advantages of this technique include a bloodless operative field with a flaccid myocardium. A continuous infusion of saline at 4 degrees C provides a simple and effective method of creating myocardial hypothermia. While topical hypothermia has been used successfully with anoxic intervals of 120 minutes, recent evidence indicates that in patients with combined coronary disease and ventricular hypertrophy, the degree of protection is inadequate after 70 minutes. Further investigation is needed to define more completely the degree and length of protection and to identify those situations in which the protection becomes inadequate.

Heart Arrest, Induced↗
PubMed1975

Operative treatment in hypertrophic subaortic stenosis. Techniques, and the results of pre and postoperative assessments in 83 patients.

The results of operative treatment in 83 patients with idiopathic hypertrophic subaortic stenosis (IHSS) are described. Most patients with the disease are asymptomatic, or derive satisfactory symptomatic improvement from nonoperative therapy: administration of propranolol, exerice limitation, control of arrhythmia, etc. Operation is required, however, in 10-15% of patients, those who remain severely symptomatic after nonoperative treatment or who become refractory to it. Operation relieves symptoms in IHSS by relieving obstruction to left ventricular outflow, and for a patient to be considered an operative candidate severe obstruction must be documented at left heart catheterization either under resting conditions or after provocative interventions. All 83 patients were severely incapacitated--58 in Class III and 24 in Class IV. Seventy had obstruction at rest (average gradient 96 mm Hg), and 13 had only provocable obstruction. At operation the hypertrophic interventricular septum was exposed via an aortotomy, and a vertical bar of muscle was resected between parallel myotomy incisions. There were six operative deaths (7%); no patient has died since 1970. Seven patients have died late after operation, five of them from causes unrelated to their heart disease or the operation. All surviving patients describe symptomatic improvement. Fifty-two patients with obstruction at rest preoperatively (average gradient 95 mm Hg) have been studied postoperatively: no resting gradient was evident in 47, while in the remaining five the gradient was less than 25 mm Hg. Recurrence of obstruction has never been observed at late catheterization (21 pts) or late echocardiographic examination (37 pts). Obstruction could not be provoked postoperatively in ten of the 11 patients who had large gradients only with the Valsalva maneuver or isoproterenol administration preoperatively. Obstructed and provocable obstructed patients had similar symptomatic improvement after operation. A variety of rhythm and conduction abnormalities were observed both pre and postoperatively, and these are described in detail. The results of operation in these 83 patients with IHSS demonstrate that gratifying symptomatic and hemodynamic improvement uniformly follows left ventriculomyotomy and myectomy. Relief of obstruction and amelioration of symptoms have proved to be long-lasting during postoperative observation periods extending to 14 years. Continued application of the operative procedure in properly selected patients appears to be indicated.

Adolescent↗
PubMed1975

Long-term morphologic and hemodynamic evaluation of the left ventricle after cardiopulmonary bypass. A comparison of normothermic anoxic arrest, coronary artery perfusion, and profound topical cardiac hypothermia.

In order to assess the long-term effects of cardiopulmonary bypass (CPB) in combination with pupular methods of myocardial protection, 37 dogs were placed on CPB for 100 minutes with the use of a bubble oxygenator without hemodilution. A separate group (I) of eight normal dogs served as a control for assessment of hemodynamic changes. The operative groups were as follows: II, continuous coronary perfusion with an empty, beating heart for 60 minutes at 35 degrees C.; III, hypothermic anoxic arrest (aortic occlusion) for 60 minutes with topical cold saline lavage (4 degrees C.); IV, anoxic arrest for 60 minutes at 35 degrees C. Subgroups of Groups III and IV received intracoronary perfusion with Ringer's lactate or Sacks' solution during aortic occlusion and were compared with those animals receiving no perfusion. Survival in Groups II and III was significantly better than in Group IV (82 and 92 per cent vs. 45 per cent). Coronary perfusion with Ringer's lactate or Sack's solution did not influence survival. The 23 survivors from all groups underwent left heart catheterization and LV cineangiography 5 months after operation. All three operative groups had significant elevation of LVEDP and depression of maximum developed dp/dt when compared with normal dogs. Ejection fraction was significantly depressed in Groups III and IV, and there was evidence of left ventricular hypokinesia and/or akinesia in all three operative groups. Differences in function between Groups II, III, and IV were not significant. The use of intracoronary solutions during anoxic arrest did not significantly influence these functional alterations. Evidence of subendocardial fibrosis was found in each of the operative groups, with the most marked changes found in the normothermic arrest group. Moderate fibrosis was present, however, in some survivors in both the continuous coronary perfusion and topical hypothermic arrest groups. These data indicate that although survival is greatly enhanced when coronary artery perfusion or topical hypothermia is used, neither method prevents chronic deterioration in ventricular function nor the development of subendocardial fibrosis.

Animals↗
PubMed1975

Experimental coronary artery fistula.

Despite numerous clinical reports of coronary artery fistulas, there have been no laboratory models. A circumflex coronary-pulmonary artery fistula was constructed with a vein graft in 11 adult foxhounds. A temporary intravascular shunt obviated the need for cardiopulmonary bypass. Measurements of aortic flow, arterial pressure, left ventricular pressure and its derivative, heart rate, and flow in the proximal coronary, distal coronary, and fistula were made with the fistula open and closed in 9 animals. Mean fistula flow was 89 c.c. per minute, representing a 1.1:1 left-to-right shunt. Mean proximal coronary flow increased 211 per cent, and there was a relative steal of 26 per cent of distal coronary flow with the fistula functioning. Phasic flow patterns showed continuous systolic and diastolic flow in the proximal coronary artery and fistula. Despite the striking changes in coronary flow patterns, there was no significant effect on measured left ventricular function. Futher uses for this model and variations of it aresuggested.

Animals↗
PubMed1974

Hypothermic asanguineous circulatory arrest in adult dogs.

A new technique for the institution of hypothermic asanguineous circulatory arrest (HACA) is described and evaluated. It employs rapid cooling and hemodilution at high flow rates. Survival and protection of neurologic and other organ function were obtained using asanguineous circulatory arrest, and the method appears to be an improvement over circulatory arrest using conventional methods for cooling. The total duration of extracorporeal circulation is much shorter than with currently used methods of circulatory arrest. Applications of this technique in general and transplantation surgery as well as cardiac surgery are discussed.

Alanine Transaminase↗