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The determinants of the shape of the pulmonary input impedance spectrum were investigated using a mathematical model based on Womersley's equations for pulsatile flow in constrained viscoelastic tubes and structural data (morphometry, elasticity, and rheology) provided for the entire cat lung by Zhuang et al. Mean distending pressures and diameters of vessels were determined from the structural data and four independent variables: cardiac output and left atrial, pleural, and alveolar pressures. Studies were performed in a control model and a model whose structure was designed to imitate that of a subject with pulmonary vascular impairment. Model simplifications were investigated. Increasing left atrial pressure or cardiac output caused passive distention of vessels that increased total blood volume and decreased vascular resistance, creating a slight spectral shift downward and to the right. Increasing pleural pressure decreased total blood volume and increased vascular resistance, creating a spectral shift upward and to the right. Increasing levels of alveolar pressure resulted in increased vascular resistance and pressures and a shift in blood volume from the capillaries to the arteries without significant change in total blood volume, creating a spectral shift that was slightly downward and to the right . Model simplification studies demonstrated that (1) all vessels distal to the tenth generation (arteries with zero distending pressure diameters < 50 μM) can be modelled as a simple resistor or (2) all vessels distal to the fourth generation can be modelled as a modified Windkessel. Results obtained from the passive studies were consistent with those obtained from normal lambs and lambs with chronically elevated pulmonary blood flow. To model a hypertensive state created by injury to the lung microvasculature, the number and size of small vessels and the compliance constants of all arteries were decreased and the viscoelastic constant was increased, which created the requisite shift to the right and upward. To better match the modulus fluctuation and negative phase angles at higher frequencies in the hypertensive animals, the development of a major reflection site between the main and branch arteries was hypothesized.

New volume requirements for coronary artery bypass grafting are being imposed on cardiac surgeons by hospitals, managed care groups, and others. The rationale for this is unclear. The available literature as well as additional sources relating volume and outcomes in cardiac surgery were extensively reviewed and reexamined. There are no data to conclusively indicate that outcomes of cardiac operations are related to a specific minimum number of cases performed annually by a cardiac surgeon. Each cardiothoracic surgeon should participate in a national database that permits comparison of his or her outcomes on a risk-adjusted basis with other surgeons. Until conclusive data become available that link volume to outcome, volume should not be used as a criterion for credentialing of cardiac surgeons by hospitals, managed care groups, or others. Instead, each surgeon should be evaluated on his or her individual results.

To determine the age-related response of the remaining pulmonary parenchyma to lung resection, a matched set of 24 purebred beagle dogs underwent pneumonectomy at 6 to 10 weeks of age (group I) or at 1 year of age (group II). Eight unoperated adult beagles served as controls (group III). One year after pneumonectomy, pulmonary hemodynamics in group I were the same as those in older animals shortly after pneumonectomy and in normal control animals. Functional residual capacity, total lung capacity, single breath diffusing capacity for carbon monoxide, and static lung compliance were measured in all three groups while anesthetized and intubated. Lung volumes and diffusion capacity for carbon monoxide in group I did not differ significantly from those of control animals. Group I animals did have a lower lung compliance than the control group, but significantly greater than the group II adult pneumonectomy dogs. The adult pneumonectomy dogs (group II) had significantly lower values for lung volumes, diffusion capacity, and compliance when compared to the control group. Arterial blood gases were not significantly different among the groups. It is concluded that beagles undergoing early pneumonectomy have an increase of alveoli beyond the normal complement in the remaining lung with concomitant remodeling of the pulmonary capillary bed resulting in normal lung volumes, diffusing capacity, and gas exchange.

A new method has been developed that permits constant postoperative monitoring of mean and phasic cardiac output in patients after correction of congenital heart defects. A miniature ultrasound probe is attached to the adventitia of the ascending aorta at the conclusion of the operative procedure. This is connected to the monitoring equipment by means of polyurethane-covered wires that exit the chest wall through a small stab wound. The probe can easily be removed by gentle traction when the patient's condition is stable. The technique was developed, validated, and refined in extensive animal studies, and this report describes the first series of 20 consecutive human implants, performed between August 1984 and September 1985, in which the absolute cardiac output determination obtained with the ultrasound probe at the time of its application was correlated with cardiac output as measured with a standard electromagnetic flow probe. Fourteen male and six female patients (mean age 5.5 years) were studied. Operations performed included eight atrial septal defect repairs, four procedures for tetralogy of Fallot, three ventricular septal defect repairs, three stenotic valve corrections, and two Senning operations. One operative death occurred, but no complications were related to probe application or removal. The average cardiac output in the 20 patients as measured with the ultrasound probe was 2.2 +/- 1.1 L/min (range 0.67 to 5.27 L/min). This is nearly identical to the results noted with the electromagnetic flow probe, where the mean cardiac output was 2.3 +/- 1.2 L/min (range 0.7 to 6 L/min). Regression analysis revealed a high linear correlation (r = 0.9) between the two techniques. A monitor can display the cardiac output trend with 1 minute updates, which greatly enhance management of intravenous drug therapy and volume administration. In conclusion, this new extraluminal removable probe allows virtually continuous monitoring of the postoperative cardiac output after correction of congenital heart defects and should become a standard technique in the postoperative care of these patients.

The morbidity and 30-day operative mortality were reviewed in the 43 patients 70 years of age or older who underwent pulmonary resection between June 1976 and May 1981. In addition to their surgical illness, many of these patients had pre-existing medical conditions including: coronary artery disease (8), hypertension (14), diabetes (4), and congestive heart failure (5). The mean preoperative 1 second forced expiratory volume (FEV1) was 1.7 liters and 17 patients had an FEV1 of less than 1.5 liters. The operative mortality was 2.3% (one patient), the average duration of postoperative hospital confinement was 9 days, and 39 of 42 (93%) of the patients were discharged within 2 weeks of their operation. There were 38 postoperative complications in 25 of the 42 survivors, most of which were minor and all of which were resolved. Problems included: air leak (13), atrial fibrillation or flutter (3), myocardial infarction (1), respiratory difficulties (9), hemorrhage (2), mental confusion (3), hyperpyrexia (3), difficult-to-manage diabetes (1), and social problems (3). Only two patients required prolonged mechanical ventilation. The low operative mortality, the short postoperative stay, and the minimal number of serious complications is contrasted with other published reports describing a high-operative mortality in elderly patients. The improvement may be related to recent advances in postoperative management and anesthetic techniques. These data suggest that advanced age is not a contraindication to curative pulmonary resection.

Forty-five patients with Lillehei-Kaster pivoting disc valves had intraoperative assessment of valve hemodynamic function by simultaneous recording of aortic, left ventricular, and left atrial pressures and cardiac output. Mean transvalve gradients and prosthetic valve areas were calculated and recorded. Comparison of the results with data previously reported on the caged-ball valves indicates that the Lillehei-Kaster pivoting disc valve has superior hemodynamic characteristics.

This study follows the clinical course of 22 patients in the active phase of infective endocarditis who inderwent valve replacement at North Carolina Memorial Hospital between March, 1966, and March, 1976. At the time of operation, there was gross valve tissue destruction in 16 patients, verrucae in nine, ruptured chordae tendineae in five, and myocardial or annular abscess formation in five. Four patients survived less than 6 months after the initial operation. One survived almost 3 years before dying of recurrent carcinoma of the lung. The remaining 17 patients have been followed an average of 4.6 years. Major postoperative complications were as follows: paravalvular problem, five patients; congestive heart failure, seven patients; complete heart block, three patients; systemic arterial emboli, four patients. These complications often were associated with the preoperative presence of annular or myocardial abscess. Thus it appears that postoperative complications often result from annular structural deficiencies rather than being directly related to active infection.

Both the radiology and surgery literature mention "popcorn calcification" as a diagnostic aid in identifying pulmonary hamartomas. Nineteen patients underwent resection of pulmonary hamartomas at North Carolina Memorial Hospital between January 1969 and February 1983, representing 1.9 per cent of all thoracotomies performed for pulmonary disease. Of the 19 patients, there were 12 men (63%) and 7 women (37%), and most were asymptomatic. Chest x-ray demonstrated 12 right-sided and 7 left-sided lesions. All masses were located peripherally in the lung parenchyma and in no instance was calcification present. Fourteen wedge resections and 5 lobectomies were performed. Pathologic examination confirmed the absence of calcification; however, in two cases (11%) an associated malignancy was present. There were no operative deaths and only minor postoperative complications. All problems resolved without difficulty. These data show that pulmonary hamartomas are not commonly associated with calcification, and there may be an increased association with carcinoma of the lung. Excision can be performed with minimal morbidity and is necessary to distinguish hamartomas from malignant lesions.

Previous attempts to quantify blood flow by means of ultrasound have been hampered by inaccurate diameter measurements and failure to account for the parabolic nature of the cross-sectional velocity profile. Angiodynography (ADG) provides a B-mode image of vessel walls, and the outer flow envelope is constantly monitored to provide phasic diameter measurements throughout the cardiac cycle. Frequency shifts are color-coded to provide a real-time visual display of varying velocity patterns across the vessel lumen throughout the cardiac cycle as well as calculation of average flow velocity and mean blood flow. Simultaneous flow values obtained with ADG were compared with electromagnetic flow probe (EMF) measurements in 12 open-chest dogs. Flow was varied with volume administration and exsanguination, and 201 data points were obtained. The average flow determined by EMF was 2.0 +/- 0.9 L/min compared with 2.04 +/- 0.71 L/min for ADG. The correlation coefficient was 0.88, the y-intercept was close to zero, and the slope approached unity, confirming the ability of ADG to accurately determine volume blood flow rather than merely to establish a flow trend. It is concluded that ADG offers an accurate way of quantifying volume blood flow.

The study set out to describe the structural changes in the remaining lung of beagle dogs after left-sided pneumonectomy, performed at 6–10 wk or 1 yr of age. After a 5-yr postoperative recovery, lung volume and weight had increased in the operated groups, though only the latter was significant in comparison with 5-yr-old controls. In both operated groups, total alveolar number in the right lung was normal. The total volume of alveolar ducts, mean linear intercept, and (in the young operated group) mean alveolar volume were increased, indicating a compensatory enlargement of distal air spaces. Lobar differences reinforced these conclusions. In the 1-yr operated group, medial hypertrophy was present in preacinar arteries, with a similar trend in intra-acinar arteries where peripheral extension of medial smooth muscle was also present. Despite the lack of structural change in their pulmonary arterial system, the young operated group had right ventricular hypertrophy. Previously reported evidence of alveolar proliferation shortly after pneumonectomy probably represents a speeding up of normal developmental patterns, but after prolonged recovery the final alveolar number is no greater than normal.

The long-term effects of pneumonectomy on the pulmonary circulation quantifiable through pulmonary input impedance analysis were studied. Excision of the left lung was performed in purebred beagle dogs aged 6 to 10 weeks (n = 6 group I) or 1 year (n = 8 group II). Unoperated beagles served as controls (n = 8 group III). When the dogs were 5 years of age, pulmonary pressure and flow were measured and the impedance spectra calculated. Characteristic impedance (Zo) (indicative of changes in proximal vessel physical properties) and pulmonary vascular resistance (PVR) (indicative of the distal response) were estimated. In group III the cardiac output (CO) was 1.7 +/- 0.4 L/min, mean pressure 16 +/- 5 mm Hg, PVR 605 +/- 448 dyne-sec/cm, and Zo 204 +/- 76 dyne-sec/cm. Group I results exhibited bimodal distributions that were not statistically different from results of groups II or III; four dogs had spectra comparable to those of group III, while two dogs had developed moderate hypertension and high PVR and Zo. Group II results were more normally distributed, and comparison with group III indicated statistically significant differences (P less than 0.05) in CO (1.1 +/- 2 L/min), PVR (1396 +/- 573 dynes-sec/cm), and Zo (543 +/- 273 dynes-sec/cm). Doubling of PVR and Zo in group II indicated that proximal vessel compliance and peripheral perfusion radius had not increased following pneumonectomy in adult beagles. Group I results indicate that marked facilitory adaptation can occur when pneumonectomy is performed in puppies; however, the adaptation may not be based on true lung growth and, therefore, may not be sustained indefinitely.

The unusual occurrence of an intramural hamartoma mimicking a peptic esophageal stricture in a child is presented. Early operative intervention is indicated to diagnose the condition and to avoid certain morbidity or death. The remarkable embryologic feature of this report is the presence of annular cartilage at the site of the esophageal stricture. Conservative resection of the involved esophagus and primary anastomosis is the treatment of choice.

Sixty-three hearts with situs solitus, concordant atrioventricular connection, and more than half of both great arteries connected to the right ventricle have been studied to delineate their surgically important features. Specifically noted were the relationship of the arterial valves to each other and the type and position of the ventricular septal defect with special reference to the conduction tissue location. Infundibular morphology was ascertained and other congenital abnormalities were recorded. An estimate was made of the surgical options available given the various anatomic abnormalities present. The aorta was most commonly in the right posterior position but could be found anywhere in the arc extending to left anterior position. The septal defects were most frequently in subaortic position (34/65) and were usually of perimembranous type (45/65). Three hearts had two defects each and one heart had an intact ventricular septum. Identifying the type of defect was helpful in locating the conduction tissues. In addition, there were numerous associated anomalies, including 19 hearts with coronary artery malformations. Retrospective analysis of the surgical options suggested that 36% of the hearts would not have been operable during life. Approximately another third could have been corrected by use of an intraventricular tunnel from the ventricular septal defect to the aorta, and the remaining third would have needed more complex procedures. In the final analysis it was concluded that hearts with the ventriculoarterial connection of double-outlet right ventricle, though so varied as to preclude "standardization," did permit anatomic analysis and description in clear and consistent terms.

Analysis of 26 autopsy specimens with interruption of the aortic arch has led to a clearer understanding of the vital importance of associated cardiovascular abnormalities. In all cases there was an associated patent ductus arteriosus "supporting" the distal systemic circulation. "Proximal" septal defects, 22 ventricular septal defects and 3 aorto-pulmonary windows, were found in all but one specimen. The infundibular component of the ventricular septum was displaced posteriorly and leftward in 9 hearts resulting in significant left ventricular outflow obstruction in 8. In one specimen the infundibular septum was displaced anteriorly giving the effect of a "Fallot type" obstruction to the right ventricular outflow tract. Abnormal ventriculo-arterial connections were found in 7 hearts; 2 with discordant connection, 2 with double outlet, and 3 with single outlet of the heart. In 6 specimens there was an aberrant origin of the right subclavian from the distal aorta passing behind the esophagus to the right side. Various other arterial abnormalities were identified including a truncus arteriosus with separate but "transposed" origins of the pulmonary arteries. In short, in these hearts there were no examples of the rare situation where aortic arch interruption exists in isolation. This study therefore makes it very clear that a detailed understanding of associated anatomical abnormalities must accompany any attempt at surgical correction. Certainly in many of these cases management of the associated lesion will present more of a challenge than the difficult problem of dealing with the interrupted arch itself.