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Biomedical subjects

D G Knauf

Publications and source records attributed to D G Knauf.

At least 19 recordsLinked to original sources
PubMed1994

The changing strategies in operation for transposition of the great vessels.

Between July 3, 1985, and February 24, 1994, a total of 55 infants underwent arterial switch procedures for the repair of transposition of the great vessels. Thirty-five infants had an intact ventricular septum and 20 had ventricular septal defects. To date, there have been three late deaths, one in the group with an intact ventricular septum and two in the group with a ventricular septal defect. Early postoperative complications included atrial dysrhythmias, prolonged ventilation, inability to close the sternum, and tension on the coronary arteries. Follow-up echocardiographic data for 44 patients indicate that pulmonary artery gradients are a worrisome postoperative problem, especially in infants who have ventricular septal defects.

Child, Preschool↗
PubMed1993

Identifying Blalock-Taussig shunts using a Silastic band.

Placement of an encircling Silastic band around Blalock-Taussig shunts facilitates identification and ligation of the shunt at the time of corrective operation. This technique of "shunt banding" is particularly useful for left-sided shunts, both native and modified. We have noted no complications, specifically shunt constriction. Placement of the band adds minimal operative time during shunt placement and substantially lessens the time and amount of dissection required during subsequent procedures.

Anastomosis, Surgical↗
PubMed1992

Patient memory before and after cardiac operations.

The memories of 20 patients undergoing elective operations on the heart were assessed by a comprehensive battery of standardized psychometric tests. Testing was conducted 1 to 2 days before, 7 to 10 days after, and 1 month after each operation. Twenty age-matched, healthy control subjects were given the same battery of tests at comparable times. Compared with healthy subjects, the patient group had significantly lower scores on 3 of 19 tests before, 10 of 19 tests 1 week after, and 5 of 19 tests 1 month after surgical intervention. The patient group had similar test performances before and 1 week after the operations and improved on 3 of 19 measures 1 month after the operations. Degrees of illness and cardiopulmonary bypass variables were significantly related to only a small subset of memory measures. Results of this study are consistent with previous reports that underscore the contribution of nonspecific aspects of surgical intervention to neuropsychologic dysfunction in the immediate postoperative period. We conclude that neither the illness nor the surgical variables are directly related to substantial variance in cognitive function after operations on the heart.

Adult↗
PubMed1991

Pancoast tumor: radiation therapy alone versus preoperative radiation therapy and surgery.

This is a retrospective analysis of 73 patients with non-oat cell carcinoma of the lung presenting as a Pancoast tumor. All patients were treated with curative intent between October 1964 and September 1987 (minimum follow-up 2 years). The treatment plan consisted of preoperative radiation therapy (usually 3000 cGy in 2 weeks or 4500 cGy in 5 weeks) in 41 patients and radiation therapy alone (usually 6500-7000 cGy in 6.5-8.0 weeks) in 32 patients. In general, radiation therapy alone was reserved for poor-prognosis patients (extensive disease or medical inoperability). Although 41 patients were initially scheduled to receive preoperative radiation therapy and surgery, the surgery was not performed in 12 cases (29%) because of patient refusal (4 patients), poor response to radiation therapy (4 patients), distant metastasis (2 patients), or debilitation (2 patients). Separate calculations were carried out for the patients who completed the surgery as planned (preoperative radiation therapy and surgery) and the entire group originally scheduled for combined-modality therapy. There was no significant difference in the absolute or cause-specific survival rates between treatment groups, but severe complications were significantly more common in patients receiving combined therapy.

Adult↗
PubMed1991

The Blalock-Taussig shunt in the newborn infant.

Children with pulmonary oligemia often require palliation in the newborn period. The Blalock-Taussig shunt has been shown to offer adequate palliation in the older child, but its use in the newborn period remains controversial. A retrospective review of 51 neonates younger than age 2 weeks undergoing a Blalock-Taussig shunt (or modification) was performed. The operative mortality rate was 5.8%. Six children (15.4%) required reoperation in the first year of life for inadequate shunt function. The modification with interposition grafts necessitated reoperation more often than shunts performed with the subclavian artery.

Anastomosis, Surgical↗
PubMed1988

Bovine pericardial patch fibrosis requiring reoperation.

Glutaraldehyde-fixed bovine pericardium (GFBP) has multiple uses. Its use as a vascular patch material is under investigation. A case report of severe fibrosis causing early reoperation of a GFBP patch used to repair coarctation of the aorta is presented.

Aortic Coarctation↗
PubMed1985

Coronary artery bypass graft surgery: clinical comparison of cold blood potassium cardioplegia, warm cardioplegic induction, and secondary cardioplegia.

An analysis of myocardial protection was performed in 45 low-risk patients undergoing coronary bypass procedures who were divided into three equal groups with similar preoperative ejection fractions and coronary artery obstructions. Group 1 (N = 15) received cold blood cardioplegia, Group 2 received cold blood cardioplegia and secondary cardioplegia, and Group 3 received cold blood cardioplegia plus warm cardioplegic induction. The aortic cross-clamp time and the number of bypass grafts were similar among the groups. The following variables were measured serially: electrocardiographic changes, serum myocardial-specific isoenzyme of creatine kinase, cardiac output, left ventricular filling pressure, ejection fraction, and left ventricular wall motion. The three methods evaluated were all effective in protecting the myocardium during global myocardial ischemia. Patients who received secondary cardioplegia (Group 2) were more likely to exhibit spontaneous defibrillation (12/15) than those in Group 1 (5/15) or Group 3 (6/15) (p less than 0.05). However, measurements of left ventricular performance and evidence of perioperative myocardial infarction were similar among all three groups. These data suggest that a standard technique of cold potassium cardioplegia alone should be the method of choice in elective, low-risk coronary bypass operations rather than this technique in combination with either of the other two more costly and complex methods evaluated in this study.

Cold Temperature↗
PubMed1985

Mortality, morbidity, and cost-accounting related to coronary artery bypass graft surgery in the elderly.

The purpose of this study was to document early mortality, perioperative complication rate, duration of hospitalization, and costs related to coronary artery bypass graft (CABG) surgery in the elderly. Arbitrarily, elderly patients were defined by age greater than or equal to 65 years; younger patients were less than or equal to 60 years old. A detailed list of specific perioperative complications was analyzed. Early (30-day) mortality was similar between groups, while 120-day mortality was higher among elderly compared with younger patients (7.6% versus 1.3%; p = 0.05). The number of elderly patients with 1 or more complications was also higher than among the younger patients (62% versus 43%; p = 0.05). When the incidences of atrial arrhythmias and transient psychoses were considered minor complications and excluded from consideration, the incidence of major complications was higher in the elderly: 41 major events among 76 younger surviving patients compared with 89 major complications in 61 older surviving patients (p = 0.001). Time spent in the intensive care unit and the duration of postoperative hospitalization were also greater in the elderly (p = 0.01 and p = 0.001, respectively). Finally, the elderly group incurred greater costs than the younger patients (p = 0.03). The likelihood of increased perioperative morbidity in elderly patients is documented in this study. Also, it appears that the increased frequency of complications in elderly patients is associated with a longer hospital stay and greater financial expense. Consequently, the careful preoperative evaluation of these patients, including cautious patient selection, assumes greater importance. After CABG procedures, the highly symptomatic elderly patient may experience dramatic relief of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1985

Emergency coronary artery bypass graft surgery for threatened acute myocardial infarction related to coronary artery catheterization.

In 20 patients undergoing cardiac catheterization, usually involving balloon-catheter dilation or streptokinase infusion, catheter-induced coronary artery intimal damage resulted in severe chest pain, electrocardiographic evidence of obstruction or dissection of a major coronary artery. These patients were surgically revascularized within 8 hours after the onset of the acute chest pain syndrome. Our experience with pharmacological and catheter-related manipulations to improve coronary blood flow after the ischemic episode but before operation suggested that the additional time spent in the catheterization laboratory was worthwhile. The injured coronary artery was the left anterior descending in 10 patients, the right in 8, the left main in 1 patient, and an obtuse marginal branch of the circumflex in 1. The average number of grafts per patient was 2.5; only 6 patients had single bypass grafts. In 5 patients, intraaortic balloon pumping was used either preoperatively or postoperatively. Inotropic support was used postoperatively in 5 patients, and 7 patients received lidocaine for ventricular irritability. Abnormal elevation of the serum isoenzyme of creatine kinase (CK-MB) was seen in 8 patients, and new Q waves were noted in 4 patients; 3 of these 4 patients with new Q waves also had abnormal serum CK-MB levels. Global ejection fraction obtained by the equilibrium-gated blood pool scan postoperatively was 60 +/- 3%, which was similar to the 62 +/- 3% obtained from the contrast-determined ventriculogram done preoperatively prior to the catheter-related injury. There were no early or late deaths, but morbidity was much higher in the group who had emergency coronary artery bypass grafting (CABG) compared with those who had elective CABG.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1984

Intraoperative balloon-catheter dilatation: University of Florida experience.

Thirty-four patients with stable angina underwent coronary artery bypass surgery with supplemental intraoperative coronary artery balloon-catheter dilatation. Coronary dilatation was performed on 35 vessels at 50 sites. The balloon catheter could not be passed through one stenotic site. Intimal dissection occurred at two sites, as noted on early postoperative angiographic studies, with resolution on follow-up studies. There was one perioperative myocardial infarction, 100% early relief of angina, and one operative death. Of 25 distal arterial narrowings studied early by angiography (mean, 10 days), 15 (60%) were unchanged, two (8%) were worse, and eight (32%) were improved. Discrete narrowings improved more than diffuse narrowings; in 46% of the former there was an increase in luminal diameter, in comparison to only 17% of the latter. During a maximal 34-month follow-up period, two patients developed recurrent angina and one died of congestive heart failure. Of 13 distal coronary narrowings studied late (mean, 1 year), six (46%) were unchanged, three (23%) were worse, and four (31%) were improved. Postoperative serial catheterization (early and late) of 10 distal narrowings revealed that nine were unchanged and one was worse. Adjunctive intraoperative coronary balloon-catheter dilatation can be performed safely with acceptable clinical results. The procedure may also allow more complete revascularization of the myocardium.

Angina Pectoris↗
PubMed1984

Coronary artery bypass graft surgery: relative efficacy of initial proximal versus distal anastomoses.

Controversy exists concerning the most appropriate sequence of anastomoses in coronary artery bypass grafting (CABG) procedures. While the more commonly employed method of distal coronary anastomoses first has withstood a long clinical experience, a recent study and several cardiac surgical groups have suggested that construction of the proximal anastomoses first offers certain advantages. In 30 patients undergoing CABG, we performed a prospective, randomized trial comparing both techniques. Relative efficacy was assessed by hemodynamic, radionuclide, electrocardiographic, enzymatic, thermographic, and clinical evaluation. The length of cardiopulmonary bypass was longer in the group having the distal anastomoses done first. Myocardial temperature mapping was similar between groups. Hemodynamic changes, including cardiac output, ejection fraction, and regional wall motion, were nearly identical between the groups. The incidence of myocardial damage reflected by levels of myocardial-specific isoenzymes (serum CK-MB) and electrocardiographic changes was also similar. In conclusion, the sequence of anastomoses is not critical in routine CABG operations. However, we speculate that each technique may have certain advantages under different clinical circumstances found on occasion. Ideally, each method should be part of the coronary surgeon's armamentarium.

Angina Pectoris↗
PubMed1984

Biochemical and ultrastructural integrity of the saphenous vein conduit during coronary artery bypass grafting. Preliminary results of the effect of papaverine.

Factors associated with early and late graft patency related to aorta-coronary artery bypass grafting with a reversed segment of saphenous vein are clinically important. The present investigation examines the biochemical and electron microscopic integrity of this venous conduit intraoperatively with regard to pharmacologic manipulation with papaverine. Portions of saphenous vein were analyzed in 22 patients undergoing coronary artery bypass operations. Levels of a stable derivative of prostacyclin, 6-keto-PGF1 alpha, were measured by radioimmunoassay. Scanning as well as transmission electron microscopy was also performed. In particular, the efficacy of local vein treatment with papaverine, a phosphodiesterase inhibitor, was evaluated. We found that levels of 6-keto-PGF1 alpha in venous effluent showed a biphasic response with initial elevation followed by a relative depression after papaverine exposure. There were no such changes observed in veins subjected to a balanced electrolyte solution (Plasma-Lyte). In addition, levels of the platelet-inhibitory substance 6-keto-PGF1 alpha in venous tissue were less in papaverine-treated veins than those found in veins treated only with the balanced electrolyte solution (Plasma-Lyte). Furthermore, evidence for ultrastructural damage was also somewhat greater in the papaverine-treated group. An alternative method of dilating the saphenous vein after harvesting, which involves the creation of the proximal aorta-coronary anastomosis first and gentle finger manipulation subsequently, appeared to minimize venous injury. Under present clinical conditions, it appears that some amount of injury is inevitable during harvesting and suturing of the human saphenous vein during coronary bypass grafting.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Comparison of early and long-term results with intraoperative transluminal balloon catheter dilatation and coronary artery bypass grafting.

Twenty-six patients with chronic stable angina underwent intraoperative coronary artery balloon catheter dilatation and concomitant coronary artery bypass grafting (CABG). In one patient (3.8%) the catheter could not be passed through the arterial narrowing, and in two patients (8%) early angiographic evidence for arterial damage was detected. Postoperative angiographic data were available in 85% of patients early (mean 10 days) and in 50% of patients late (mean 12 months). Early results showed one perioperative myocardial infarction, 100% relief of angina, and no operative mortality. Compared to preoperative studies, of 23 angiographically visualized distal narrowings dilated in an antegrade fashion, 12 (52%) were unchanged, two (9%) were worse, and nine (39%) were improved. Those arterial segments with discrete distal narrowings (n = 13) had better angiographic results than those with diffuse distal narrowings (n = 9). In 49% of the former and in 22% of the latter arterial narrowings, improvement (increased luminal diameter) was documented postoperatively. In addition, there were four proximal narrowings which were dilated in a retrograde fashion; three were unchanged and one was improved compared to preoperative studies. Only one of 27 dilated segments (3%) was totally occluded postoperatively. Late results showed two patients (8%) developed recurrent chest pain and one patient (4%) died related to congestive heart failure. The two patients who had angiographically documented coronary arterial intimal injury showed evidence of resolution at late study. In 13 distal narrowings, six (46%) were unchanged, three (23%) were worse, and four (31%) were improved compared to the preoperative appearance. In 10 distal narrowings visualized both early and late postoperatively, nine were unchanged and one was worse. In summary, coronary artery balloon catheter dilatation during CABG is relatively safe and is associated with acceptable clinical results. Angiographic evidence for improvement is less than symptomatic relief postoperatively. Therefore, objective evaluation may be necessary for accurate determination of operative results. The need for a national registry related to intraoperative angioplasty is probably warranted.

Angina Pectoris↗
PubMed1982

Preliminary experience with intraoperative transluminal balloon-catheter dilation and coronary artery bypass grafting for the treatment of symptomatic diffuse coronary artery disease.

Transluminal balloon-catheter dilation of coronary artery lesions has become increasingly common in the cardiac catheterization laboratory. We describe a method of intraoperative dilation that may improve surgical results when used in combination with coronary artery bypass graft (CABG) operations in patients with diffusely diseased coronary arteries. In 16 patients, long-segment intraoperative dilations were performed to enlarge luminal narrowings in 21 different regions. All of these patients had postoperative coronary angiography and left ventriculography so that we could objectively evaluate the coronary dilatations. There were no operative deaths or perioperative myocardial infarctions, and angina was relieved in all patients. Of the 21 dilated segments, 12 (57%) were unchanged, 2 (10%) became worse, and 7 (33%) were improved postoperatively. In addition, two new areas of intimal damage were detected in patients with unchanged postoperative liminal diameters. We conclude that further experience and longer follow-up are necessary before the efficacy of intraoperative coronary artery balloon-catheter dilation can be accurately determined.

Angioplasty, Balloon↗