Ronald C. Hill

Biatrial approach to cardiac myxomas: A 30-year clinical experience

Early surgical intervention for atrial myxomas mitigates morbidity and usually offers cure. The operative approach to resect these tumors is controversial. The purpose of this study was to review our experience with the biatrial approach between 1964 and 1994. The location of the myxoma was left atrium in 17 and right atrium in 3. Mean preoperative New York Heart Association functional classification was 2.7. Surgical approach to the tumor was biatrial in all patients. There were no perioperative strokes, myocardial infarctions, or deaths. Mean follow-up was 7.5 years (range, 2 mo to 27 years) with a postoperative New York Heart Association functional classification of 1.4. One late death occurred, which was unrelated to the myxoma. Advantages of biatrial approach include (1) definition of tumor pedicle by direct visualization, (2) minimal manipulation of the tumor, (3) adequate margins of excision, (4) inspection of all heart chambers, and (5) secure closure of the atrial septal defect. Long-term follow-up demonstrates the efficacy of this operative approach to atrial myxomas.

Early Primary Repair of Tetralogy of Fallot

Young age, low weight, and the requirement for transannular patch reconstruction of the right ventricular outflow tract (RVOT) are thought to adversely affect intracardiac repair of tetralogy of Fallot. Forty patients underwent complete repair between January, 1984, and January, 1987. Only infants with pulmonary atresia, complete atrioventricular canal, or coronary artery anomalies were shunted initially. The malalignment ventricular septal defect was closed with a Dacron patch. Infundibular resection was minimized. All atrial communications were left open. Thirty-four patients (85%) had a transannular RVOT patch, and 2 patients (5%) had a nontransannular patch. All 10 infants weighing 3.4 to 9.6 kg had a transannular RVOT patch at 7 weeks to 12 months of age. An RVOT patch was used in 26 of 30 children operated on between 1 and 6 years of age (median age, 24 months). No patient undergoing intracardiac repair died. Postoperative RVOT pullback gradients were between 0 and 35 mm Hg (mean, 18.5 mm Hg). Postoperative pulmonary artery saturation (mean, 73%) did not reveal any residual ventricular septal defect. The right ventricular/arterial pressure ratio was always less than 0.6 (mean, 0.4). All children are doing well at follow-up from two to 37 months. Serial echocardiograms reveal no residual ventricular septal defect and only 1 moderate RVOT gradient. Follow-up cardiac catheterization in 15 patients revealed no residual ventricular septal defect and RVOT gradients between 5 and 35 mm Hg. The right ventricular/left ventricular pressure ratio was always less than 0.6 (mean, 0.48). The early and late results justify continued primary repair of tetralogy of Fallot in symptomatic children, regardless of age or weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective lung ventilation during thoracoscopy: Effects of insufflation on hemodynamics

BACKGROUNDnPositive-pressure insufflation during thoracoscopy has been advocated by some authors to facilitate exposure of the intrathoracic structures by expediting collapse of the lung. We hypothesized that insufflation during thoracoscopy may result in hemodynamic compromise despite selective lung ventilation.nnnMETHODSnAfter placement of invasive monitoring lines, six adult swine underwent selective lung ventilation and thoracoscopy. Baseline measurements of hemodynamic indices were taken before selective lung ventilation. The right lung then was collapsed; data were obtained at insufflation pressures up to 10 mm Hg and were compared with baseline values using Students t test.nnnRESULTSnCardiac index, mean arterial pressure, and left ventricular stroke work index decreased, whereas pulmonary artery and central venous pressures increased (p < 0.05) at insufflation pressures of 5 mm Hg and greater.nnnCONCLUSIONSnPositive-pressure insufflation during thoracoscopy resulted in significant hemodynamic compromise despite the use of selective lung ventilation. Conversion to thoracotomy may be an alternative if positive-pressure insufflation is necessary to perform the thoracoscopic procedure.

Intralobar sequestration. A missed diagnosis.

Intralobar pulmonary sequestration is an uncommon but distinct clinical entity that may be the unrecognized cause of recurrent pulmonary infections. Between 1967 and 1987, 10 patients, ranging in age from 5 to 39 years, were found to have an intralobar sequestration. Nine patients (90%) had a history of recurrent pulmonary infections, chronic cough, and intermittent fevers. One patient was asymptomatic. Many patients had been treated with antibiotics on numerous occasions. The delay in diagnosis varied between 3 months and 7 years (mean delay, 1.5 years). The chest roentgenogram was abnormal in all patients. The intralobar sequestration was present in the left lower lobe in 7 patients and the right lower lobe in 3 patients. Bronchography was abnormal in 4 patients in whom it was done. Bronchoscopy was performed in 7 patients, but it was only helpful in excluding other diagnoses. Preoperative thoracic arteriography in 9 patients visualized the systemic arterial supply from the thoracic or abdominal aorta to the intralobar sequestration and helped prevent any catastrophic surgical bleeding. A lobectomy was performed in 9 patients and a segmentectomy in 1 patient without morbidity or mortality. In patients with recurrent infections in the same lower lobe, a high index of suspicion for an intralobar sequestration should prompt early diagnostic arteriography and, if confirmed, early operative intervention.

Role of lung decortication in symptomatic empyemas in children

Despite appropriate antibiotics and pleural drainage, the condition of some children with empyema fails to improve. In a 5-year period, 10 children ranging in age from 2 to 16 years underwent lung decortication for a refractory, symptomatic empyema, which had developed 3 to 5 weeks after an initial pneumonic infiltrate. Responsible organisms included beta-hemolytic streptococci, Haemophilus influenzae, or Streptococcus pneumoniae in 6 children. Negative cultures were found in 4 children. The initial computed tomographic scan of the chest in 4 of 8 patients showed more than 75% limitation of lung expansion by the contents of the empyema cavity. In 4 other patients, an extensive pleural peel was seen on initial computed tomographic scan of the chest. Several studies also showed cystic lesions in the collapsed lung. Multiple computed tomographic scans in 3 patients confirmed the lack of clinical and chest roentgenographic improvement with conservative therapy. At decortication in each, the visceral and parietal pleural peel was completely removed, freeing the trapped lung. Two patients also had a concomitant lobectomy for a necrotic right upper lobe (1 patient) and left lower lobe (1). Clinical improvement was marked, with return of temperature, white blood cell count, and appetite to normal. Postoperative morbidity was minimal. Analysis of these patients in whom traditional conservative therapy failed suggested that the initial management during the early exudative phase was often delayed and was not aggressive enough from the standpoint of pleural drainage.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of heparin-coated cardiopulmonary bypass

A 49-year-old man with unstable angina and a history of severe anaphylaxis to seafood and intravenous iodine needed myocardial revascularization. Because of concern of an intraoperative protamine reaction, preoperative treatment was instituted with steroids and with H1 and H2 blockers. Revascularization was accomplished using a heparin-coated cardiopulmonary bypass circuit. Complement activation and postoperative bleeding were minimal. Heparin-coated cardiopulmonary bypass is a safe, effective technique of bypass in select patients.

Cardiac response to nitric oxide synthase inhibition using aminoguanidine in a rat model of endotoxemia.

This study evaluates the effect of aminoguanidine, a preferential inhibitor of inducible nitric oxide synthase (iNOS), on the prevention of cardiac depression in acute endotoxemia. Cardiac performance was evaluated after 4 h of exposure to endotoxin. Rats (n = 5) were selected randomly to receive, by intraperitoneal injection, one of four treatments: saline, LPS (lipopolysaccharide, E. coli, 4 mg/kg, AG (aminoguanidine 100 mg/kg), and LPS + AG at various times. AG and saline treatments were administered 30 min before LPS and at 1 and 3 h after LPS injection. Hearts were perfused using the Langendorff isolated perfusion system and a balloon-tipped catheter was placed into the left ventricle to measure left ventricular developed pressure (LVDP). Myocyte contractile function was assessed with electrical field stimulation and video microscopy. Tissue was immunostained for the expression of iNOS and for nitrotyrosine, a byproduct of protein nitration by peroxynitrite. Perfused hearts from LPS-treated rats exhibited a 57% decrease (P < 0.05) in LVDP compared to saline-treated animals. No improvement in ventricular function was observed with the administration of AG. Similarly, cardiac myocytes prepared from LPS-treated animals demonstrated a significant (P < 0.05) reduction in percent and velocity of shortening and this effect was unaltered with the same dose of AG. AG administration significantly reduced serum nitrite/nitrate levels (P < 0.05) in endotoxemic rats to control levels. Localized expression of iNOS in the myocardium was lessened with AG treatment and was not associated with peroxynitrite formation in this model of endotoxemia. The results indicate that AG given in vivo before and after endotoxin (at a concentration sufficient to decrease NO production) did not reduce cardiac depression. We conclude that selective inhibition of iNOS and the reduction of NO production do not prevent cardiac dysfunction at an early stage in an acute model of endotoxemia.

Resolution of experimental pneumothorax in rabbits by oxygen therapy

The treatment of asymptomatic patients with small pneumothoraces (ie, less than 20% by volume) has included observation, tube thoracostomy, and operation. When observation is used, the anticipated expansion of the lung has been estimated to be 1.25% of the lung volume daily. This study was designed to evaluate the use of inhaled oxygen as a method to accelerate the resolution of a pneumothorax in a rabbit model. Experimental pneumothoraces were created in 23 white New Zealand rabbits. Group 1 (9 rabbits) were placed in a cage with room air and group 2 (11 rabbits) were placed in a cage with high oxygen concentration. Three rabbits died before completion of the study. Serial chest roentgenograms were performed until the pneumothoraces resolved. The majority of rabbits treated with oxygen had resolution of their pneumothoraces by 36 hours, whereas the majority of rabbits treated with room air did not show complete resolution before 48 hours. Biopsies showed no evidence of damage secondary to oxygen treatment. Oxygen treatment was found to be significantly better in the early resolution of pneumothoraces when compared with room air. This establishes an alternative treatment for some pneumothoraces that are small and asymptomatic.

Safe use of heparin-coated bypass circuits incorporating a pump-oxygenator

Durable, covalently bonded, heparin-coated cardiopulmonary bypass (CPB) circuits with oxygenators have been developed. Proposed advantages of heparin-coated CPB circuits include improved biocompatibility and thromboresistance. The purpose of this study was to evaluate our experience with heparin-coated CPB circuits in 20 patients. Heparin was given to maintain an activated clotting time equal to or greater than 200 seconds, while flow rates were kept equal to or greater than 2 L/min. Indications for use of this circuit included recent stroke, posttraumatic injuries, recent gastrointestinal bleeding, protamine allergies, combined cardiac and noncardiac procedures, and ventricular assist. Mean heparin dosage was 0.50 +/- 0.18 mg/kg and protamine dosage was 57.14 +/- 39.36 mg. Postoperative blood loss and transfusion requirements were minimal. Postoperative complement levels of C3a and C5a were normal, suggesting excellent biocompatibility. There were no deaths or perioperative complications. Heparin-coated CPB circuits using a pump oxygenator can be used safely with low-dose heparin administration in select patients requiring CPB.

Resolution of experimental pneumothorax in rabbits by graded oxygen therapy.

BACKGROUNDnSmall pneumothoraces have been treated by observation and tube thoracostomy in asymptomatic patients. Using a rabbit model, we demonstrated previously that inspired oxygen at 60% FiO2 hastened the time to resolution of complete pneumothoraces compared with room air. The present study was designed to evaluate the use of lower levels of inspired oxygen and to establish a dose-response curve for the treatment of experimental pneumothoraces.nnnMETHODSnForty New Zealand White rabbits were divided randomly into four groups: room air (21%) and 30, 40, and 50% FiO2. Experimental pneumothoraces were created in the rabbits, and the animals were placed in cages with the designated level of inspired oxygen. Serial chest radiographs were performed until the pneumothoraces resolved.nnnRESULTSnPneumothoraces treated with room air resolved in 61.65 +/- 12.30 hours. Those treated with 30% FiO2 resolved in 42.90 +/- 5.97 hours, with 40% FiO2 in 35.80 +/- 4.26 hours, and with 50% FiO2 in 33.80 +/- 4.66 hours.nnnCONCLUSIONnThese results show a statistically significant (p < 0.01) dose-dependent improvement in the resolution of pneumothoraces with increasing levels of inspired oxygen. Supplemental oxygen therapy may be used to facilitate the resolution of small, uncomplicated pneumothoraces.