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Biomedical subjects

H W Bender

Publications and source records attributed to H W Bender.

At least 55 records · Page 3Linked to original sources
PubMed1985

Tetralogy of Fallot: selective surgical management can minimize operative mortality.

Although tetralogy of Fallot can be completely corrected at any age, it appears that preliminary shunting may be of benefit in infancy. To better define the optimum age for shunting, the following patient data were reviewed. One hundred five patients with tetralogy of Fallot were treated between December, 1975, and July, 1984. Eight of 100 patients undergoing intracardiac repair died. Operative mortality was 14.3% (4 of 28 patients) when intracardiac repair was done before the patient was a year old, but only 5.6% (4 of 72 patients) after that age. Seven (13%) of 54 patients requiring transannular patch reconstruction of the right ventricular outflow tract died, whereas only 1 (2.2%) of 46 having repair without this type of reconstruction died (p less than 0.05). Twenty-one patients were initially palliated with systemic-pulmonary artery shunts, with 1 noncardiac death related to associated congenital neurological anomalies (4.8%). There was no statistically significant difference in mortality for primary versus secondary intracardiac repair. Left ventricular end-diastolic volume determination in 26 patients less than 2 years old demonstrated that 14 patients had small left ventricles and that 3 of them less than 1 year of age died at corrective operation. The remaining 12 had a left ventricle of normal size, and 1 of them died at operation. Palliative shunts can be performed safely in the very young child with no increased mortality at subsequent intracardiac repair. Diffuse hypoplasia of the right ventricular outflow tract and pulmonary arteries requiring transannular patch reconstruction, and age less than 1 year both alter operative mortality, their combined impact being additive.

Adolescent↗
PubMed1985

The results of valve replacement for mitral valve prolapse.

Between January, 1975, and December, 1982, 33 patients underwent mitral valve replacement for mitral valve prolapse secondary to myxomatous degeneration. The majority were in the seventh decade of life (median age, 62 years), and all were seen with symptoms of mitral regurgitation. Echocardiography was more accurate in making the diagnosis of mitral valve prolapse more often (75%) than angiography (66%). Thirty-eight percent of the patients who underwent cineangiography had concomitant coronary artery disease and had coronary artery bypass grafting as well as mitral valve replacement. There was 1 operative death, an operative mortality of 3%. There were 6 late deaths, a late mortality of 18%. Of the 26 long-term survivors, 23 (88%) were in New York Heart Association Functional Class I and 3 (12%) were in Class II. The average length of follow-up was 33.25 months, and the 5-year actuarial survival was 76%. There was only one incident of thromboembolism (3%). Short-term and long-term survival were not related to the severity of mitral regurgitation but to the status of the left ventricle and the overall condition of the patient. These data suggest that older patients with severe mitral regurgitation secondary to mitral valve prolapse can undergo valve replacement with low operative mortality and gratifying long-term results.

Actuarial Analysis↗
PubMed1985

Amelioration of the deleterious effects of platelets activated during cardiopulmonary bypass. Comparison of a thromboxane synthetase inhibitor and a prostacyclin analogue.

Thrombocytopenia and platelet dysfunction are commonly seen after cardiopulmonary bypass. In addition, the microvascular bed of ischemic myocardium is a potent stimulus for platelet deposition and microvascular plugging. Thus, it would appear theoretically advantageous to provide pharmacologic protection of platelets by inhibiting their response to activating agents and thereby preventing their loss into the extracorporeal circuit; this would further inhibit myocardial platelet deposition and the deleterious effects therein. Twenty-one mongrel dogs were placed on cardiopulmonary bypass with 30 minutes of normothermic global ischemia. They were randomly assigned to receive pretreatment with an infusion of saline (control, n = 8), a thromboxane synthetase inhibitor (RO-22-4679, n = 5), or a prostacyclin analogue that does not produce hypotension (ZK 36,374, n = 8). The platelet count in those animals treated with ZK 36,374 was significantly higher at the end of the experiment than in the control group (102.8 +/- 10.7 X 10(3) versus 69.7 +/- 10.6 X 10(3), p less than 0.01); the animals treated with RO-22-4679 had a platelet count between the other two groups (92.8 +/- 14.8 X 10(30)), which was not significantly different from either. Myocardial platelet deposition was measured with indium 111-labeled platelets. Those animals treated with ZK 36,374 had a much lower level of platelet deposition than the group of controls; again the RO-22-4679 group had values between the other two. Finally, myocardial blood flow after global ischemia and cardiopulmonary bypass, measured with radioactive microspheres, was significantly higher in the ZK 36,374 group than in the control group. We conclude that ZK 36,374 prevents platelet consumption during cardiopulmonary bypass over and above that seen with inhibition of thromboxane synthesis alone. It also prevents deposition of platelets into the myocardium after global ischemia and we presume by that mechanism increases myocardial blood flow.

Animals↗
PubMed1985

Pathophysiology of chronic cyanosis in a canine model. Functional and metabolic response to global ischemia.

To investigate the pathophysiology of chronic cyanosis, we subjected 14 adult mongrel dogs to diversion of the inferior vena cava to the right inferior pulmonary vein. This produced a mean oxygen tension of 42 +/- 2 mm Hg and a calculated right-to-left shunt of 52.0% +/- 3.9%. These animals (Group C) and 15 normal dogs (Group N) were subjected to cardiopulmonary bypass with 20 minutes of normothermic global ischemia. Functional indices studied were rate of rise of left ventricular pressure and the end-systolic pressure/volume ratio. Metabolic status was assessed by obtaining transmural myocardial biopsy specimens for measurement of adenosine triphosphate content. Myocardial blood flow was measured with radiolabeled microspheres. There were no significant differences between Group C and Group N in either functional index or blood flow measurement prior to global ischemia. At 45 minutes after ischemia, Group N animals had a significantly greater rate of rise of left ventricular pressure (at a left ventricular end-diastolic pressure of 0, 5, 10, and 15 mm Hg, p less than 0.025 to 0.05) and subendocarial perfusion (endocardial/epicardial flow ratio 0.961 +/- 0.037 versus 0.815 +/- 0.021, p less than 0.01). At 90 minutes after ischemia, Group N animals exhibited a significantly higher end-systolic pressure/volume ratio (4.9 +/- 0.7 versus 3.0 +/- 0.4 mm Hg/ml, p less than 0.05), rate of rise of left ventricular pressure (at an end-diastolic pressure of 0 to 20 mm Hg, p less than 0.005 to 0.05), and endocardial/epicardial flow ratio (1.065 +/- 0.046 versus 0.829 +/- 0.059, p less than 0.01). No differences in adenosine triphosphate content were found at any sampling period. The Group C left ventricles exhibited no hypertrophy but were significantly dilated compared to Group N (38.8 +/- 0.3 versus 30.1 +/- 0.2 mm, p less than 0.05). Inferior vena cava to pulmonary vein diversion produces cyanosis with left ventricular dilatation but without hypertrophy. It is proposed that abnormal loading characteristics of the left ventricle are responsible for the functional derangements that result from global ischemia.

Adenosine Triphosphate↗
PubMed1985

Improved right ventricular function after intra-atrial repair of transposition of the great arteries.

Current interest in the arterial switch operation for simple transposition of the great arteries (TGA) has led us to evaluate our latest patients who have undergone intra-atrial repair. Right ventricular function and overall results were compared in 32 patients who had undergone the Senning procedure between 1978 and 1983 and 26 patients who had undergone Mustard repair between 1971 and 1978). Deep hypothermia and circulatory arrest were used in all Senning operations and in 18 of 26 Mustard procedures. Cardiac catheterization was performed an average of 1 year after surgery in all patients. Postoperative right ventricular ejection fraction (EF) was below normal (less than 0.49) in 16 of 32 patients who underwent the Senning procedure and averaged 0.48 +/- 0.09. In the patients in this group with abnormal right ventricular EFs after repair there was a fall in the value after surgery (0.51 to 0.40, p less than .001), while in those with normal right ventricular EFs after repair there was no change (0.57 to 0.55, NS). All 32 patients who underwent the Senning procedure were compared with 26 patients who underwent the Mustard operation (13 treated between 1971 and 1974 and 13 treated between 1975 and 1978). An older age at surgery (12 +/- 7 vs 6 +/- 8 months, p less than .006) and a lower preoperative right ventricular EF (0.46 +/- 0.09 vs 0.54 +/- 0.08, p less than .007) characterized the Mustard vs the Senning group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1984

Incidence and prognosis of seizures in infants after cardiac surgery with profound hypothermia and circulatory arrest.

Fifteen of 165 infants and young children who underwent surgical correction of congenital cardiac defects using profound hypothermic and circulatory arrest experienced generalized or focal seizures postoperatively. The cause of the seizures was unexplained in ten. Among these ten, the onset of seizures was 25 to 48 hours after surgery. With appropriate treatment, all had complete seizure control by the third postoperative day. During 11 to 54 months (mean, 35.6 months) of follow-up, no further seizures occurred and none had neurological abnormalities. Long-term anticonvulsant therapy was not required for any of the children. There was no correlation between the type of cardiac abnormality (cyanotic v acyanotic) or the duration of hypothermic circulatory arrest and the development of seizures. Unexplained seizures following cardiac surgery with hypothermia and circulatory arrest are not a sign of permanent brain damage and do not detract from the use of this technique for early definitive repair of congenital heart defects.

Body Weight↗
PubMed1984

Perioperative beta blockade with propranolol: reduction in myocardial oxygen demands and incidence of atrial and ventricular arrhythmias.

To determine the effect of beta blockade with propranolol on myocardial oxygen demands and postoperative arrhythmias in patients having coronary bypass operations, 50 patients with chronic stable angina undergoing operation were randomized in a double-blind fashion to receive either propranolol (60 mg every 6 hours) or a placebo. Drug administration began 24 to 48 hours prior to operation and continued through the operative period and for one month after operation. There were no deaths. Two perioperative myocardial infarctions occurred, both in patients receiving a placebo. Myocardial oxygen demand as measured by the rate-pressure product (heart rate X mean arterial pressure) was significantly reduced during induction of anesthesia (7,658 +/- 451 versus 5,786 +/- 340; p less than 0.002) and during sternotomy (8,400 +/- 550 versus 6,756 +/- 384; p less than 0.02) in propranolol-treated patients. In the first two postoperative days, nitroprusside was required for control of hypertension of 10 patients in the placebo group but in only 3 patients given propranolol (p less than 0.05). Postoperatively, 15 of the 26 patients who received a placebo had 45 episodes of arrhythmia. Seven of the 24 propranolol-treated patients had 17 episodes (p less than 0.04). We conclude that propranolol given perioperatively in doses large enough to induce beta blockade significantly reduces myocardial oxygen demands in the vulnerable period during induction of anesthesia and sternotomy, reduces the need for antihypertensive therapy in the immediate postoperative period, and causes a marked reduction in the incidence and frequency of both supraventricular and ventricular arrhythmias in the postoperative period.

Angina Pectoris↗
PubMed1984

The feasibility of adjuvant surgery in limited-stage small cell carcinoma: a prospective evaluation.

Forty patients with limited-stage small cell carcinoma of the lung were prospectively evaluated for adjuvant surgery after intensive chemotherapy to determine resectability. All patients giving informed consent and having a Karnofsky performance status greater than or equal to 50% were included in the study, which ran from May, 1980, to September, 1982. Ages ranged from 40 to 70 years (median, 59 years). One patient was lost to follow-up. Thirty-nine patients were evaluated for operation 9 to 15 weeks after diagnosis and after having received two to four cycles of chemotherapy intravenously every 3 weeks (cyclophosphamide, 1,000 mg/m2; doxorubicin, 50 mg/m2; vincristine, 1 mg/m2; VP-16, 300 mg/m2). Two patients had clinical Stage I tumors; 12 patients, Stage II; and 25 patients, Stage III. At the time of reevaluation there were 13 (33%) complete responders, 21 (54%) partial responders, and 5 (13%) with stable disease. Eleven (28%) of the 39 patients underwent thoracotomy using standard resection criteria for non-small cell carcinoma. Eight of these 11 had resectable lesions (2, Stage I; 3, Stage II; 3, Stage III); five pneumonectomies and three lobectomies were performed. Tumor was present in six of eight specimens. Twenty-eight patients were not candidates for operation for various reasons: poor pulmonary function, 5; unresectable tumors, 10; refusal, 6; very poor medical condition, 6; and primary site not identified, 1. Median survival for complete responders was 17 months and for partial responders, 11 months. We have prospectively identified suitable candidates for adjuvant surgery among the total group (denominator population) of patients with limited-stage small cell carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

The questionable role of computed tomography in preoperative staging of esophageal cancer.

The findings of computed tomography (CT) in 18 patients with histologically proven esophageal carcinoma were compared with operative and pathological findings. Computed tomography delineated esophageal lesions in 14 of the 18 patients. In 11 patients, CT scanning was found to be inaccurate in assessing tumor involvement of esophageal lymphatic drainage. Nine patients had no abdominal nodal metastasis demonstrated by CT scan. Operative exploration revealed tumor involvement of celiac or left gastric lymph nodes in all of these patients. Two patients' CT scans demonstrated tumor involvement of celiac and left gastric lymph nodes; at operative exploration, these nodes were enlarged, but they were histologically negative for esophageal carcinoma. Operative exploration changed the preoperative TNM classification in 8 of the 11 patients. Review of these data indicates that surgical exploration continues to be the only reliable method of determining the actual extent and often the resectability of esophageal carcinoma.

Adenocarcinoma↗
PubMed1984

Global ischemia in the immature canine ventricle. Enhanced protective effect of verapamil and potassium.

The efficacy of the addition of verapamil to a cardioplegic solution was evaluated in immature canine hearts subjected to normothermic global ischemia. Two groups of mongrel puppies less than 10 weeks old were subjected to 30 minutes of global myocardial ischemia while on cardiopulmonary bypass. One group (Group K) was arrested with cardioplegic solution containing 20 mEq/L of KCl; the other group (Group K + V) was arrested with the same solution containing 0.2 mg/kg of verapamil. Ultrasonic crystals were placed for measurement of left ventricular dimensions, and micromanometers measured left ventricular pressures. Functional measurements included left ventricular strain, first derivative of left ventricular pressure (dP/dt), and the end-systolic pressure/volume ratio (Emax). Metabolic recovery was assessed by measuring myocardial adenosine triphosphate (ATP) content. Ninety minutes following ischemia, Group K + V exhibited greater minor axis strain at a left ventricular end-diastolic pressure of 15 and 20 mm Hg (p less than 0.05), greater dP/dt (p less than 0.05 to 0.001), and greater Emax (p less than 0.05) than Group K. ATP content in Group K + V was greater at 60 minutes (Group K + V: 12.74 +/- 1.60 mumol/gm; Group K: 8.39 +/- 1.30, p less than 0.05) and 90 minutes (Group K + V: 10.34 +/- 0.46; Group K: 7.55 +/- 1.42, p less than 0.05) after ischemia. The addition of verapamil to a cardioplegic solution containing potassium enhances the recovery of function and high-energy phosphate stores in the immature myocardium following normothermic global ischemia.

Animals↗
PubMed1983

Arteriovenous fistula of the lung.

Pulmonary arteriovenous fistula is an unusual but not rare abnormality with more than 450 cases reported in the literature. Studies during the last 30 years have established the effective prevention of morbidity and relief of symptoms by operative excision. During the last 25 years, the Vanderbilt University Affiliated Hospitals have seen 7 patients with pulmonary arteriovenous fistula. This experience prompted a review of the literature. Particular emphasis is placed on current means of diagnosis and therapy.

Adult↗
PubMed1983

A reproducible model of chronic hypoxemia.

This report presents our experience with producing a stable chronic hypoxemia preparation in the dog without the disadvantages of prosthetic graft insertion or sacrifice of pulmonary tissue. In 28 adult dogs, the intrapericardial inferior vena cava and the area of junction of the right and left inferior pulmonary veins were exposed through a right thoracotomy. The cava was clamped at the diaphragm and at the right atrium, divided at the atrial clamp, and quickly anastomosed to the inferior pulmonary veins. The mean arterial O2 tension (PaO2) decreased from 83.2 +/- 1.6 mmHg preoperatively in mechanically ventilated (room air) animals to 35.3 +/- 1.5 mmHg postoperatively in awake animals spontaneously breathing room air (P less than 0.001). There was persistent depression of the PaO2 (49.1 +/- 1.8 mmHg) and elevation of the hematocrit (64.8 +/- 2.0%) in six animals tested at 18.5 mo postoperatively. Shunt patency without significant stenosis was confirmed in each animal at autopsy. This method attains predictable and persistent hypoxemia and polycythemia and is simple to perform. It may be useful in studying various aspects of ventricular function and ventricular histological and biochemical changes with chronic cyanosis.

Animals↗
PubMed1983

Radionuclide angiographic evaluation of right and left ventricular function during exercise after repair of transposition of the great arteries. Comparison with normal subjects and patients with congenitally corrected transposition.

We assessed the incidence, clinical significance and etiology of ventricular dysfunction after intraatrial repair of d-transposition of the great arteries in 11 patients, mean age 9 +/- 3 years, who had had Mustard operations. We compared the results to 15 patients who were considered to have normal ventricular function, two patients who had Rastelli operations and five patients with congenitally corrected transposition. Gated equilibrium radionuclide angiography with supine exercise stress testing was used to assess these children. We found no significant difference between our patient groups in exercise capacity, heart rate, or blood pressure response to exercise. However, we found a high incidence of right ventricular dysfunction in the patient groups, manifested by an abnormal right ventricular ejection fraction response to dysfunction in the patient groups, manifested by an abnormal right ventricular ejection fraction response to exercise in six of 11 patients with a Mustard repair, both patients with a Rastelli repair and all five with congenitally corrected transposition. In addition, the left ventricular response to exercise was abnormal in 10 of 11 patients who had undergone a Mustard repair, both patients with a Rastelli repair, and two of five patients with congenitally corrected transposition. We conclude that biventricular dysfunction is frequently present after intraatrial repair of d-transposition of the great arteries. Despite this dysfunction, no significant decrease in exercise tolerance is found in childhood.

Adolescent↗
PubMed1983

Left ventricular performance after coronary artery bypass surgery. Prediction of functional benefit.

Global left ventricular performance (ejection fraction) and regional function were studied by rest-exercise radionuclide ventriculography in 36 patients before and after (23 +/- 8.5 wk) they had coronary artery bypass surgery for stable angina pectoris. The exercise ejection fraction was less than the resting ejection fraction before surgery (n = 36,p = 0.006), but not after surgery. The degree of postoperative improvement correlated with the degree of preoperative dysfunction (r = 0.55, n = 36, p less than 0.001). Improvement was most likely to occur if exercise-induced dysfunction was present preoperatively (n = 15,p = 0.001), even with old myocardial infarction. Regional dysfunction during preoperative exercise was also likely to improve postoperatively (n = 18, p = 0.001). Protocol design is important in determining the results and their interpretation. Matching postoperative exercise loads to preoperative loads and using regional analysis with two imaging projections improved judgment of the results. Regional dysfunction was commoner than global dysfunction and was less sensitive to workloads than was ejection fraction. This study shows that coronary artery bypass surgery can improve left ventricular performance on exercise if preoperative tests indicate the presence of ischemia-induced dysfunction.

Adult↗
PubMed1982

The subxiphoid approach to pericardial disease.

During the 36-month period from July, 1978, through July, 1981, 25 patients underwent a subxiphoid pericardial window procedure for diagnosis and therapy. Twelve patients were operated on for uremic pericarditis, 6 for malignancy, and 7 for etiological diagnosis of the pericarditis. All 12 patients with renal failure had enlarging effusions, despite aggressive dialysis. Eleven of the 12 are alive, free from recurrence, 3 to 36 months postoperatively. Six patients were operated on for suspected pericardial malignancy with hemodynamic compromise. Histological diagnosis was made from the pericardial tissue in all patients; only 1 patient lived more than 43 days following the procedure. In the group of 7 patients operated on for diagnosis, 4 were thought preoperatively to have tuberculous pericarditis. All 4 were treated with anti-tuberculosis chemotherapy and are asymptomatic, without evidence of calcification, 12 to 31 months postoperatively. This diverse group of patients demonstrates that the subxiphoid pericardial window is an effective approach for relief of uremic effusions and may adequately treat effusive tuberculous pericarditis when combined with multidrug chemotherapy. Patients with suspected malignant pericardial disease and hemodynamic compromise need to be carefully studied before an operative procedure is considered as a means of diagnosis and therapy.

Adult↗
PubMed1982

Functional and metabolic preservation of the immature myocardium with verapamil following global ischemia.

This study investigated the effects of the calcium antagonist verapamil on the functional and biochemical recovery of the immature heart following 30 minutes of normothermic ischemia. Verapamil (0.2 mg per kilogram of body weight) was infused into the aortic root in 5 puppies (8 to 10 weeks of age) prior to cardiopulmonary bypass. Five additional puppies received saline solution as a control. Left ventricular developed pressure, rate of rise of left ventricular pressure (dP/dt), left ventricular endsystolic pressure-diameter relationship (emax), compliance, and water content were assessed before and after bypass. Serial myocardial biopsies for adenosine triphosphate (ATP) and creatine phosphate were obtained. Puppies pretreated with verapamil recovered more than 80% of the preischemic left ventricular developed pressure, dP/dt, and emax in contrast to 50% recovery in the controls (p less than 0.05). The ATP content declined 40% during the interval of ischemia in the control puppies, versus 14.6% in the verapamil-treated puppies (p less than 0.05). Myocardial compliance was preserved in the verapamil-treated puppies and was associated with significantly less myocardial water content (78% versus 80.1% in the controls)(p less than 0.01). This study demonstrates the protective effects of verapamil on the immature heart during ischemic arrest. These results suggest that verapamil may be a useful adjunct to current methods of protecting the infant heart during cardiopulmonary bypass.

Adenosine Triphosphate↗
PubMed1982

Alterations in pulmonary function following pneumonectomy for bronchogenic carcinoma.

Twenty-one patients who underwent pneumonectomy for bronchogenic carcinoma at the Nashville Veterans Administration Hospital from November, 1977, to March, 1980, were evaluated with standard pulmonary function tests preoperatively and postoperatively. Twelve patients had Stage I disease, 4 patients had Stage II, and 5 patients had Stage III disease. The interval between the operative procedure and postoperative testing ranged from 2 to 33 months (mean, 12.4 months). Mean functional loss of pulmonary capacity after pneumonectomy was based on analysis of preoperative and postoperative forced vital capacity (FVC) and initial-second forced expiratory volume (FEV1) indices. The mean functional loss as expressed by FVC was 41.5% after right pneumonectomy and 34.0% after left pneumonectomy. The mean functional loss as expressed by FEV1 was 40.2% after right pneumonectomy and 38.3% after left pneumonectomy. The postoperative functional status of each patient was classified according to the New York Heart Association criteria. Nineteen of the 21 patients were in Class I or II preoperatively. Postoperatively, 10 patients were in Class I or II and 11 in Class III or IV. The results indicate that a postoperative FVC less than 2.5 liters and FEV1 less than 1.5 liters are not compatible with active life.

Carcinoma, Bronchogenic↗