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Biomedical subjects

G A Kaiser

Publications and source records attributed to G A Kaiser.

At least 19 recordsLinked to original sources
PubMed1999

Acetaminophen effects on behavioral thermoregulation in albino rats.

Acetaminophen (N-Acetyl-p-aminophenol) was administered intraperitoneally to 15 Sprague-Dawley rats partitioned into 3 studies (5 rats per study) using a within subjects, repeated-measures reversal design. Behavioral thermoregulation was assessed in a cold Skinner Box using 5-sec. exposures of microwave radiation [Specific Absorption Rate = 0.34 Watts/kg/(mW/cm2)] as reinforcing stimuli under a fixed-interval 2-min. schedule of positive reinforcement. Doses of 10, 20, 30, 40, and 50 mg/kg (in solutions of 1%, 2%, 3%, 4%, and 5%) acetaminophen showed stable rates of operant responding for heat compared with significant changes in rates for comparable doses of aspirin in a 1993 study by Vitulli, et al. Weight reductions and temperature increases varied significantly with before-session and after-session measures, respectively. 1994-95 biochemical data of Murphy, et al. from humans following aspirin or acetaminophen ingestion which affect thermoregulation and sleep patterns are discussed in conjunction with behavioral data from rats.

Acetaminophen↗
PubMed1994

Transaortic resection of the subaortic membrane. Treatment for subvalvular aortic stenosis.

In an attempt to better understand congenital subaortic stenosis, we reviewed 19 consecutive pediatric patients undergoing surgery for this problem between 1973 and 1984. Preoperative cardiac catheterization demonstrated subvalvular stenosis in all patients and associated anomalies in 11 patients. All patients underwent transaortic resection of the subaortic membrane. Five patients underwent concurrent additional cardiac procedures. An 8-month-old infant with multiple cardiac anomalies was the only operative mortality. Follow-up extended to 16 years, with a mean of 6.9 years. In five symptomatic patients, cardiac catheterization revealed a mean systolic pressure gradient of 33.0 +/- 31.94 mm Hg 24.7 months (mean) after surgery. Two of these patients (11.1 percent of survivors) required reoperation. Twelve of the remaining 13 asymptomatic patients underwent echocardiographic follow-up, and 4 were found to have recurrent stenosis with 1 requiring surgery (5.6 percent of survivors). Our experience shows that transaortic resection of the subaortic membrane is an acceptable treatment for subvalvular aortic stenosis, but is associated with a high incidence of recurrence requiring reoperation (3 of 18 or 16.7 percent). Consequently, it is reasonable to consider the role of alternative therapies which may help prevent recurrence in selected cases.

Adolescent↗
PubMed1993

Sequential internal mammary artery grafts for coronary artery bypass.

From 1985 to 1990, 145 patients underwent isolated coronary artery bypass with one (n = 128) or both (n = 17) internal mammary arteries (IMAs) used as sequential bypass grafts. All but 2 patients had angina pectoris preoperatively. A total of 162 sequential IMA grafts were constructed bypassing two (n = 152) or three (n = 10) coronary artery sites as in situ (n = 132) or free (n = 30) grafts. In 12 patients, one IMA was used as a nonsequential graft. Thirty-day mortality was 2.8% (n = 4 patients). Perioperative myocardial infarction occurred in 1 patient (0.7%). Only two sequential IMA grafts failed. Both were used to bypass coronary arteries 1.00 mm in diameter. Mean follow-up was 31 months (range, 6 months to 4.2 years). There were three late deaths. Of 136 survivors followed-up, 121 (89%) were free of angina. Postoperative rotational thallium 201 tomography was done in 73 patients. Myocardial ischemia was detected in 11 diabetic patients (15.1%), but corresponded to a sequential IMA graft in 4 (5.5%) and to nonsequential and venous grafts in 10 patients (13.7%). Coronary revascularization with sequential IMA grafts was safe and effective.

Adult↗
PubMed1989

Clinical experience with subxiphoid drainage of pericardial effusions.

To assess the effectiveness of subxiphoid pericardial tube drainage for treatment of pericardial effusion, we reviewed 41 consecutive patients who underwent this procedure during a 14-year period. The patients ranged in age from 7 months to 75 years. All were symptomatic preoperatively. The diagnosis of pericardial effusion was confirmed by echocardiogram in all but 2 patients. Eight patients had acute pericardial tamponade. Subxiphoid pericardial drainage was performed under general (n = 35) or local anesthesia (n = 6). A portion of the anterior pericardium was excised in each patient. There were no perioperative deaths. Thirty-day mortality was 19.5%; there were five late deaths. All deaths were unrelated to pericardial effusion or to the operation. One patient had recurrent effusion requiring pericardiocentesis on the 21st postoperative day. He died five days later of extensive lymphoma. Twenty-eight patients were followed from 1 month to 10 years; mean follow-up was 31.5 months. None developed recurrent effusion or pericardial constriction. We conclude that subxiphoid pericardial drainage is effective for treatment of pericardial effusion.

Adolescent↗
PubMed1986

Comparison of long-term results of Carpentier-Edwards and Hancock bioprosthetic valves.

The long-term survival following valve replacement with Carpentier-Edwards or Hancock bioprostheses was compared between the two valve models and between the two groups totaling 407 patients who were discharged after valve replacement beginning in 1974. The two groups of patients were treated in a nonrandomized fashion. The actuarial survival for 299 patients with Carpentier-Edwards valves was 94 +/- 1.5% (+/- standard error) and 93 +/- 1.7% after 5 and 8 years of follow-up, respectively. Comparable figures for 108 patients undergoing valve replacement with Hancock valves were 89 +/- 3.0% and 83 +/- 3.7%, respectively (p = not significant [NS]). The probability of freedom from death and valve removal after 5 and 8 years of follow-up was 91 +/- 1.8% and 79 +/- 4.6%, respectively, with the Carpentier-Edwards valve and 84 +/- 3.5% and 75 +/- 4.3%, respectively, with the Hancock valve (p = NS). An accelerated rate of attrition for both valves was observed in the mitral position. There were no significant differences in actuarial survival between the two valves in the mitral or the aortic position or in the incidence of major valve-related complications.

Adolescent↗
PubMed1985

Changing trends in the surgical treatment of coarctation of the aorta.

From 1974 through 1983, 107 patients 4 days to 27 years old underwent 115 operations for treatment of coarctation of the aorta. Thirty-two patients were infants (1 year old or younger), and 28 of them were newborns. All newborns were seen with congestive heart failure. Seventy-one patients were seen with hypertension. Associated anomalies were present in 72 patients (67%). Resection was performed in 48 patients, patch aortoplasty in 16, bypass of the coarcted segment in 15, and left subclavian artery flap angioplasty (LSAFA) in 36. Ligation of a patent ductus arteriosus was simultaneously performed in 28 patients and pulmonary artery banding, in 4. Follow-up was 6 months to 9.2 years. There was a significant difference in aortic cross-clamp time between 26 patients who had resection (37.9 +/- 12.9 minutes) (mean +/- standard deviation) and 32 patients who had LSAFA (22.9 +/- 7.7 minutes) (p less than 0.05). Six patients died within thirty days after operation; 5 of them had resection, and 1 had bypass. Major postoperative complications included bleeding requiring exploration in 3 patients (2 after resection and 1 after LSAFA) and paraplegia in 1 patient after reoperation (resection) for recurrent coarctation 3 years after patch aortoplasty. Paradoxical hypertension was observed in 13 patients, and sustained systemic postoperative hypertension developed in 11 after effective repair of coarctation. There was no significant difference in early postoperative arm-leg pressure gradients between the types of operation or the various age groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1985

Comparison of effectiveness and safety of operations on the pericardium.

A ten-year experience with operations on the pericardium in 71 consecutive patients was reviewed. The patients ranged in age from nine months to 75 years old. Fifty-three patients were operated upon for pericardial effusion and 14 for pericardial constriction. Sixty-seven patients had pericarditis: 21 of them underwent subxiphoid tube drainage; ten, limited pericardiectomy; and the remaining 36, extensive pericardiectomy. There were two trauma victims who underwent diagnostic pericardiotomy. Two patients underwent excision of pericardial cysts. There was one operative death during extensive pericardiectomy for constrictive tuberculous pericarditis. Thirty-day mortality was three of 21 patients after subxiphoid tube drainage, three of ten after limited pericardiectomy and five of 36 after extensive pericardiectomy. Postoperative complications consisted of pulmonary problems in four patients (two after pericardiectomy and two after extensive pericardiectomy), cardiac arrhythmia in one patient after tube drainage and postpericardiotomy syndrome in one patient after extensive pericardiectomy. Mean follow-up was 3.2 years. Recurrent pericardial effusion occurred in two patients; one had limited pericardiectomy but did not require reoperation and one had diagnostic pericardiotomy without drainage. Six patients with persistent postirradiation pericardial effusion were treated effectively with extensive pericardiotomy. Our experience indicates that subxiphoid tube drainage is effective for the treatment of pericardial effusion and safer than limited pericardiectomy, while extensive pericardiectomy is the operation of choice for pericardial constriction and radiation-related pericardial effusion.

Adolescent↗
PubMed1983

Failure of Hancock xenograft valve: importance of valve position (4- to 9-year follow-up).

To evaluate long-term durability of Hancock valves, we reviewed our results in 107 hospital survivors (120 valves) who were operated on during 1974 through mid-1979. Mitral valve replacement was done in 63 patients, aortic valve replacement in 20, and mitral valve replacement combined with other procedures in 24. The 7-year survival was 84 +/- 4% (standard error of the mean) for 91 patients and 97 valves. During a follow-up of 590 patient-years, 15 (12 mitral and 3 aortic) of 120 valves at risk (87 mitral, 32 aortic, 1 tricuspid) were removed from 14 patients. Six valves (3 mitral and 3 aortic) were removed because of bacterial endocarditis. One mitral valve was removed because of thromboembolism. Eight mitral valves were removed because of valve structural failure, which occurred at a mean follow-up of 42 months. These valves showed extensive calcification, leaflet perforation, or cusp tear. Structural failure was unrelated to valve size, year of implantation, or valve shelf-life. Structural failure was not seen after aortic valve replacement. Results show that structural failure of the Hancock xenograft valve in the mitral position is related primarily to valve position. After aortic valve replacement, valve failure is predominantly due to endocarditis. Although medium-term (mean, 6-year) durability of this xenograft valve compares satisfactorily with prosthetic valves, its high failure rate in the mitral position indicates the necessity for improvement in valve mounting, design, and preservation.

Adolescent↗
PubMed1980

Technical and pharmacologic management of distal hypotension during repair of coarctation of the aorta.

Neurologic and abdominal complications can occur in the postoperative period of aortic coarctation repair, ischemia being the pathogenic factor most likely to be involved. This study was designed to evaluate the extent of the hemodynamic changes proximal and distal to the coarctation at the time of cross-clamping, as well as the effects of pentolinium and isoproterenol upon the hemodynamic changes. Included in the study were 17 patients with adult type coarctations who had dual hemodynamic monitoring. During cross-clamping, there was an increase in the gradient between proximal and distal pressures, with severe distal hypotension (< 50 mm Hg) occurring in six patients. Isoproterenol corrected the hypotension in five patients, but the sixth required a surgical shunt. Pentolinium was effective for the treatment of proximal hypertension; however, it also decreased distal pressure. The ligation of collateral vessels was associated with a decrease in distal pressures as well. During cross-clamping, pentolinium was useful for the management of proximal hypertension and isoproterenol increased the distal pressures in some of the patients who presented distal hypotension. However, because of the difficulties in predicting the individual response, their administration would be best guided by dual pressure monitoring. It is postulated that the recognition and proper treatment of distal hypotension may be an important factor in the prophylaxis of postoperative complications.

Aortic Coarctation↗
PubMed1977

Effects of coronary bypass surgery on the electrical activity of revascularized myocardium. Immediate and early postoperativeobservations.

The effect of myocardial revascularization on bipolar epicardial electrograms was recorded with fixed wire electrodes from revascularized left ventricular sites and from control sites on the right ventricle. Studies were performed during and after surgery in 19 patients undergoing aorta-coronary bypass grafting for occlusive coronary artery disease and in 6 additional patients having aortic valve replacement for isolated aortic valve disease. In the latter 6 patients, neither left nor right ventricular electrogram voltage changed immediately following aortic valve replacement; however, left ventricular electrogram voltage gradually decreased for 5 days postoperatively. In the 19 patients with coronary artery disease, electrogram voltage in the revascularized area increased immediately following coronary bypass grafting (+40 to +300 per cent) in 13 patients (68 per cent) and immediately decreased (-20 to -70 per cent) in 6 patients (32 per cent). In 5 of the patients showing immediate increases, temporary occlusion of the bypass grafts for 3 minutes during surgery resulted in a decrease of electrogram voltage in the distribution of the occluded bypass, followed by return to preocclusion levels after release. Postoperative monitoring of electrogram voltage for 5 days in all patients with coronary artery disease revealed that the electrogram voltage in the revascularized area decreased to or below control levels in 16 patients (84 per cent) and remained increased in 3 patients (16 per cent). These observed changes did not correlate with preoperative hemodynamics, number of grafts, graft flow rate, aortic cross-clamp time, cardiopulmonary bypass time, and the early postoperative course. These preliminary observations suggest that coronary bypass grafting does affect the electrophysiological state of the revascularized myocardium. However, the mechanism by which it occurs and its clinical implications remain to be determined.

Adult↗
PubMed1976

The ductus debate: ligation in prematurity?

This report describes 20 premature infants who have undergone surgical ligation of a patent ductus arteriosus (PDA), diagnosed solely by physical examination in all but 2 instances. There were no operative deaths. Eleven of these 20 infants had severe associated hyaline membrane disease (HMD) necessitating mechanical ventilatory support from the first or second day of life. Only 3 of these 11 infants (27%) ultimately survived to leave the hospital. In contrast, 8 of 9 premature meonates (89%) with severe congestive heart failure but without HMD were discharged alive. Surgical ligation of the PDA in a premature infant is an appropriate and successful mode of treatment when congestive heart failure is refractory to medical management. Proof is lacking, however, to establish the efficacy of PDA ligation in the premature infant with HMD.

Cardiac Catheterization↗
PubMed1976

Clinical and hemodynamic criteria for use of the intra-aortic balloon pump in patients requiring cardiac surgery.

In order to establish criteria for elective use of the intra-aortic balloon pump (IABP) in patients having cardiac surgery, we conducted a retrospective study of 43 patients who required counterpulsation, because of inability to be weaned from cardiopulmonary bypass, between May, 1972, and June, 1974. Patients in cardiogenic shock preoperatively were excluded. The 43 patients included 23 (Group A) who had severe preoperative left ventricular dysfunction with a mean cardiac index less than 1.8 L. per minute per square meter, ejection fraction less than 30 per cent, and end-diastolic pressure greater than 22 mm. Hg; 20 patients (Group B) had a combination of moderate cardiac dysfunction (cardiac index less than 2.2, ejection fraction less than 40, end-diastolic pressure less than 18) in the presence of acute infarction or severe aortic stenosis (gradient greater than 80 mm. Hg) with or without coronary disease. An inverse relationship was noted between survival and delay from completion of operation to the use of 1ABP. Thirty-two of 43 patients were weaned off bypass and were balloon assisted for 12 to 96 hours postoperatively; 25 patients were discharged (58 per cent). In Subgroup A, 14 of 23 (60 per cent) and, in Subgroup B, 9 of 20 (45 per cent) were long-term survivors. Based on these findings, 45 patients were operated upon between June, 1974, and December, 1975, with elective use of 1ABP and were assessed by serial hemodynamic studies. Sixteen had severe preoperative left ventricular dysfunction similar to Subgroup A and 29 had moderate dysfunction in combination with pathology similar to Subgroup B. Fifteen of these patients were hemodynamically unstable at time of arrival in the operating room; 1ABP was inserted under local anesthesia. Thirty-nine patients (87 per cent) were weaned off bypass and were hospital survivors. In Subgroup A, 13 of 16 (81 per cent) and, in Group B, 21 of 29 (72 per cent) were long-term survivors. Criteria for elective use of 1ABP in cardiac surgery should include severe preoperative left ventricular dysfunction or a combination of moderate dysfunction with coronary or valvular pathology. Elective 1ABP improves the survival with trivial iatrogenic morbidity.

Assisted Circulation↗