Histologic evidence of the safety of endoscopic saphenous vein graft preparation.

BACKGROUND: Endoscopic methods of saphenous vein procurement have recently been introduced. These techniques have been successful in limiting pain and wound complications, but less information on assessing potential trauma to the harvested vein segment is available. METHODS: Fourteen male patients undergoing coronary artery bypass grafting were included in the study. Nine patients underwent endoscopic procurement of saphenous vein whereas 5 patients underwent procurement using standard open techniques. Histologic appearance and immunohistochemical studies (factor VIII:vWF [von Willebrand factor protein] and CD34) of the vein segments were reviewed in a blinded fashion. RESULTS: On histologic analysis, no differences in the intima, media, or adventitia were found between endoscopically and conventionally obtained vein segments. Immunohistochemical staining for factor VIII:vWF and CD34 showed no differences between veins harvested by the two techniques. CONCLUSIONS: Endoscopic saphenous vein harvesting does not appear to traumatize the vessel wall any more than open techniques. Longitudinal assessment is necessary to evaluate long-term patency in vein grafts procured using this method.

Preventing mediastinal shift after pneumonectomy does not abolish physiological compensation.

To determine the role of mediastinal shift after pneumonectomy (PNX) on compensatory responses, we performed right PNX in adult dogs and replaced the resected lung with a custom-shaped inflatable silicone prosthesis. Prosthesis was inflated (Inf) to prevent mediastinal shift, or deflated (Def), allowing mediastinal shift to occur. Thoracic, lung air, and tissue volumes were measured by computerized tomography scan. Lung diffusing capacities for carbon monoxide (DL(CO)) and its components, membrane diffusing capacity for carbon monoxide (Dm(CO)) and capillary blood volume (Vc), were measured at rest and during exercise by a rebreathing technique. In the Inf group, lung air volume was significantly smaller than in Def group; however, the lung became elongated and expanded by 20% via caudal displacement of the left hemidiaphragm. Consequently, rib cage volume was similar, but total thoracic volume was higher in the Inf group. Extravascular septal tissue volume was not different between groups. At a given pulmonary blood flow, DL(CO) and Dm(CO) were significantly lower in the Inf group, but Vc was similar. In one dog, delayed mediastinal shift occurred 9 mo after PNX; both lung volume and DL(CO) progressively increased over the subsequent 3 mo. We conclude that preventing mediastinal shift after PNX impairs recruitment of diffusing capacity but does not abolish expansion of the remaining lung or the compensatory increase in extravascular septal tissue volume.

Postpneumonectomy alveolar growth does not normalize hemodynamic and mechanical function.

Immature foxhounds underwent 55% lung resection by right pneumonectomy (n = 5) or thoracotomy without pneumonectomy (Sham, n = 6) at 2 mo of age. Cardiopulmonary function was measured during treadmill exercise on reaching maturity 1 yr later. In pneumonectomized animals compared with Sham animals, maximal oxygen uptake, ventilatory response, and cardiac output during exercise were normal. Arterial and mixed venous blood gases and arteriovenous oxygen extraction during exercise were also normal. Mean pulmonary arterial pressure and resistance were elevated at a given cardiac output. Dynamic ventilatory power requirement was also significantly elevated at a given minute ventilation. These long-term hemodynamic and mechanical abnormalities are in direct contrast to the normal pulmonary gas exchange during exercise in these same pneumonectomized animals reported elsewhere (S. Takeda, C. C. W. Hsia, E. Wagner, M. Ramanathan, A. S. Estrera, and E. R. Weibel. J. Appl. Physiol. 86: 1301-1310, 1999). Functional compensation was superior in animals pneumonectomized as puppies than as adults. These data indicate a limited structural response of conducting airways and extra-alveolar pulmonary blood vessels to pneumonectomy and suggest the development of other sources of adaptation such as those involving the heart and respiratory muscles.

Compensatory alveolar growth normalizes gas-exchange function in immature dogs after pneumonectomy.

To determine the extent and sources of adaptive response in gas-exchange to major lung resection during somatic maturation, immature male foxhounds underwent right pneumonectomy (R-Pnx, n = 5) or right thoracotomy without pneumonectomy (Sham, n = 6) at 2 mo of age. One year after surgery, exercise capacity and pulmonary gas-exchange were determined during treadmill exercise. Lung diffusing capacity (DL) and cardiac output were measured by a rebreathing technique. In animals after R-Pnx, maximal O2 uptake, lung volume, arterial blood gases, and DL during exercise were completely normal. Postmortem morphometric analysis 18 mo after R-Pnx (n = 3) showed a vigorous compensatory increase in alveolar septal tissue volume involving all cellular compartments of the septum compared with the control lung; as a result, alveolar-capillary surface areas and DL estimated by morphometry were restored to normal. In both groups, estimates of DL by the morphometric method agreed closely with estimates obtained by the physiological method during peak exercise. These data show that extensive lung resection in immature dogs stimulates a vigorous compensatory growth of alveolar tissue in excess of maturational lung growth, resulting in complete normalization of aerobic capacity and gas-exchange function at maturity.

Fixed maximal stroke index in patients after pneumonectomy.

Patients who have undergone pneumonectomy (PNX) show limited exercise capacity, partly attributable to an impaired stroke index (SI). To determine whether this limitation is due to deconditioning, we assessed exercise performance and cardiopulmonary function in seven patients after PNX (age: 59 +/- 2 yr, mean +/- SEM) and eight normal, healthy nonsmokers (52 +/- 3 yr) before and after an ergometer exercise training program for 30 min per day, 5 d per week, for 8 wk at 65% of measured maximal O2 uptake. Lung volume, diffusing capacity of carbon dioxide (DL(CO)) and cardiac index (CI) were determined during steady-state exercise by a rebreathing method. Exercise endurance was measured at 80% of maximal power. As compared with normal subjects, patients who had had PNX showed diminished maximal oxygen uptake (VO2max), as well as diminished lung volumes, ventilatory capacities, and maximal cardiac and stroke indexes. After training, VO2max, endurance, and peripheral O2 extraction improved in both groups. However, maximal cardiac and stroke indexes increased only in normal subjects and not in patients. We conclude that an irreversibly fixed maximal SI is a major source of exercise limitation after PNX, probably because of pulmonary arterial hypertension and/or mechanical distortion of the cardiac fossa. Ventilatory impairment after PNX did not prevent a training-induced increase in VO2max. Exercise training confers significant functional benefit on postpneumonectomy patients by enhancing peripheral O2 extraction.

Early evacuation of traumatic retained hemothoraces using thoracoscopy: a prospective, randomized trial.

BACKGROUND: Failure to adequately evacuate blood from the pleural space after trauma may result in extended hospitalization and complications such as empyema. METHODS: Patients with retained hemothoraces were prospectively randomized to either a second tube thoracostomy (group 1, n = 24) or video-assisted thoracoscopy (VATS) (group 2, n = 15). Group 1 patients in whom additional tube drainage failed were subsequently randomized to either VATS or thoracotomy. Study end points included duration and costs of hospitalization. RESULTS: During a 4-year period, 39 patients were entered into the study. Patients in group 2 had shorter duration of tube drainage (2.53 +/- 1.36 versus 4.50 +/- 2.83 days, mean +/- standard deviation; p < 0.02), shorter hospital stay after the procedure (3.60 +/- 1.64 versus 7.21 +/- 5.30 days; p < 0.02), and shorter total hospital stay (5.40 +/- 2.16 versus 8.13 +/- 4.62 days; p < 0.02). Hospital costs were also less in this group ($7,689 +/- 3,278 versus $13,273 +/- 8,158; p < 0.02). There was no mortality in either group. No group 2 patient required conversion to thoracotomy. In 10 group 1 patients additional tube placement failed, and this subset was randomized to VATS (n = 5) or thoracotomy (n = 5). No significant difference in clinical outcome was found between these subgroups. CONCLUSIONS: In many patients treated only with additional tube drainage (group 1), this therapy fails, necessitating further intervention. Intent to treat with early VATS for retained hemothoraces decreases the duration of tube drainage, the length of hospital stay, and hospital cost. Early intervention with VATS may be a more efficient and economical strategy for managing retained hemothoraces after trauma.

In vivo assessment of changes in air and tissue volumes after pneumonectomy.

We examined the progression and topographical distribution of postpneumonectomy volume changes in immature foxhounds undergoing right pneumonectomy (R-Pnx, n = 5) or sham pneumonectomy (Sham, n = 6) at 2 mo of age and subsequently raised to maturity. Volumes of lung air (Vair) and tissue (Vti) were estimated by computerized tomography (CT) scan at 7, 22, and 52 wk after surgery at a transpulmonary pressure of 20 cmH2O. Estimates of Vti by CT scan included both septal tissue as well as nonseptal tissue (small- and medium-sized airways and blood vessels); these were compared with estimates of septal Vti by an acetylene rebreathing (Rb) method. We found significant correlations between these techniques (Vair(CT) = 0.83 Vair(Rb) + 275, R = 0.97; Vti(CT) = 1.62 Vti(Rb) - 30, R = 0.81). Extravascular septal Vti returned to normal 7 wk after R-Pnx and remained normal up to maturity. Nonseptal Vti remained significantly below normal. The greatest increase in Vti occurred in the midlung region just cephalad and caudal to the heart. After an early period of accelerated tissue growth after R-Pnx, the rate of septal tissue growth matched that of somatic growth, whereas nonseptal tissue growth lagged behind. Compensatory growth of the remaining left lung was not associated with selective alterations in thoracic development.

Temporal course of gas exchange and mechanical compensation after right pneumonectomy in immature dogs.

To determine the temporal progression and magnitude of functional compensation in immature dogs raised to maturity after extensive lung resection, we performed right pneumonectomy (R-Pnx) or right thoracotomy without pneumonectomy (Sham) in matched foxhounds at 2 mo of age. At 4, 8, 20, 40, and 60 wk after surgery, static transpulmonary pressure-lung volume relationships were determined. Lung diffusing capacity, membrane diffusing capacity, pulmonary capillary blood volume, pulmonary blood flow, septal lung tissue volume, and lung volumes were measured simultaneously by a rebreathing technique. During maturation, total lung capacity, lung volume at a given distending pressure, and compliance were lower in the R-Pnx group than in the Sham group (P < 0.05). Pulmonary viscous resistance at maturity was elevated after R-Pnx. There were no significant differences in total lung diffusing capacity, membrane diffusing capacity, pulmonary capillary blood volume, pulmonary blood flow, and septal lung tissue volume between groups. Compensation of alveolar-capillary gas exchange was complete by 4-8 wk after R-Pnx, but compensation of mechanical properties remained incomplete throughout maturation. Relative magnitude of compensation after R-Pnx was greater in immature dogs than in adult dogs studied previously by similar techniques.

Respiratory muscle limitation in patients after pneumonectomy.

Exercise capacity is significantly impaired in postpneumonectomy patients who have relatively normal remaining lungs. Our objectives are to determine (1) the nature and extent of mechanical ventilatory abnormalities and oxygen cost of breathing in such patients, and (2) the efficacy of a selective respiratory muscle training program in improving ventilatory and exercise performance. A group of eight postpneumonectomy and eight normal subjects (mean ages 59 and 50 yr, respectively) were studied during steady-state exercise and resting voluntary hyperventilation. Ventilation, work of breathing, cardiac output, and oxygen costs of breathing were determined. Four postpneumonectomy and five normal subjects were studied before and after a respiratory muscle training program. In patients after pneumonectomy compared with normal control subjects, maximal oxygen uptake (VO2) was 56% lower (p < 0.001). Work of breathing was significantly higher at a given ventilation. Mechanical efficiency of ventilation was lower by 44% (p < 0.05). Near maximal VO2, 48% of any additional increment of total-body VO2 was required to sustain the associated increment in ventilatory work, compared with 28% in normal subjects (p < 0.05), suggesting that competition between respiratory and nonrespiratory muscles for oxygen delivery is a significant factor limiting exercise after pneumonectomy. After respiratory muscle training, maximal respiratory pressures improved but maximal sustained ventilation and maximal VO2 did not improve significantly, suggesting that selective respiratory muscle training is of limited utility in postpneumonectomy patients.

Cardiac valve reconstruction and replacement: a brief review.

Surgical methods for improving the function of diseased cardiac valves are valve reconstruction (valvuloplasty) and valve replacement with mechanical prostheses, biologic prostheses, or homograft (donor) valves. Reconstruction is used primarily for incompetent mitral and tricuspid valves and addresses each part of the valve apparatus individually. Annuloplasty rings are often used to restore the size and shape of the valve orifice. Long-term anticoagulation therapy is not necessary. The designs of mechanical prostheses have evolved since the early caged-ball prostheses. Current models are noted for their durability. Patients who undergo implantation of these prostheses must also undergo long-term anticoagulation therapy. Biologic prostheses made from porcine valves or bovine pericardium are not as durable as their mechanical counterparts, but they do not require long-term anticoagulation therapy. Homografts are used in relatively few centers. They have good hemodynamics and do not necessitate long-term anticoagulation therapy. Radiologists should be familiar with the radiographic appearance of the various valve prostheses and annuloplasty rings and with the advantages and disadvantages of their use in cardiac valvular surgery.

Recruitment of diffusing capacity with exercise in patients after pneumonectomy.

Patients after pneumonectomy are severely limited upon exercise, but impairments in gas exchange are generally mild. One potential explanation of this observation is the existence of functional reserves of diffusing capacity (DLCO), which may be recruited during exercise, predominantly by increasing pulmonary blood flow (Qc). After pneumonectomy, DLCO reserves are recruited even at rest. To investigate if the pattern of recruitment of DLCO is altered and if reserves of DLCO are exhausted during exercise after pneumonectomy, DLCO, lung volume, and cardiac output were measured by the rebreathing method at rest and at multiple levels of steady-state exercise in eight subjects after pneumonectomy and in eight age- and sex-matched nonsmoking normal subjects. In patients after pneumonectomy, the slopes of increase in DLCO [ml.(min.mm Hg)-1.m-2] with respect to QC [ml.min-1.m-2] were normal (0.91 +/- 0.09 x 10(-3) in the pneumonectomy group, 1.16 +/- 0.12 x 10(-3) in the control group, mean +/- SE, p less than 0.05). Thus, the pattern of DLCO recruitment was not significantly affected by pneumonectomy. The ratio of DLCO/Qc fell more rapidly during exercise in patients after pneumonectomy, but the lowest value of the ratio achieved was relatively normal in all except one patient. Declines in arterial O2 saturation at exercise were mild and insufficient to explain the exercise limitation except in the patient whose DLCO/Qc fell below normal. There was no evidence that an upper limit of recruitment was approached. We conclude that the normal ability to recruit DLCO during exercise after pneumonectomy constitutes an important compensatory feature that prevents significant arterial O2 desaturation. In most patients, exercise is limited by a reduced maximal stroke index before reserves of diffusing capacity are exhausted.

Systemic arterial air embolism in penetrating lung injury.

Systemic arterial air embolism is frequently unrecognized as a cause of death among patients with isolated penetrating lung injury. Between 1975 and 1983 at Parkland Memorial Hospital, the complication of systemic arterial air embolism developed in 9 patients with penetrating lung injury (six gunshots and three stabbings). Eight patients were either in profound shock or experienced cardiac arrest and all were intubated and on positive-pressure ventilation, frequently on a manual resuscitator bag before or at the time of diagnosis. The diagnosis was made by direct visualization of air in the coronary vessels in all 9 patients, and in 3 air was also aspirated from the left ventricular apex and aortic root. In addition, 5 patients had clinically significant hemoptysis. At operation, only an isolated injury to the lung was found in 7 of the 9 patients. Arterial air embolism is a highly lethal complication; 6 of our patients died, a mortality rate of 66%. Thus, it clearly behooves us to be more alert to the possible occurrence of this complication among all victims of penetrating chest trauma. We must accept that systemic arterial air embolism is an established complication of penetrating lung injury and must recognize that it occurs much more frequently than has been previously reported. Prompt diagnosis coupled with aggressive efforts at cardiopulmonary resuscitation is crucial for successful management of patients with air embolism.

Apparatus seen on chest radiographs after cardiac surgery in adults.

The authors review the purpose, radiographic appearance, and possible complications of various tubes, catheters, and wires seen on chest radiographs after cardiac surgery. Drainage tubes, temporary epicardial wire electrodes, surgical clips, intraaortic counterpulsation balloon, atrial pressure monitor catheters, and sternal wires are reviewed. Because recent articles have discussed the Swan-Ganz catheter and automatic implantable cardioverter defibrillator, these are not covered in depth.

The effect of mannitol and dopamine on the renal response to thoracic aortic cross-clamping.

Postoperative renal failure and insufficiency are important complications of operations that require thoracic aortic cross-clamping. Successful application of pharmacologic methods to protect renal function would be clinically useful. The ability of mannitol and dopamine to prevent renal dysfunction in a canine model of thoracic aortic cross-clamping was studied. Twenty animals were divided into four equal groups, and all underwent thoracic aortic cross-clamping for 60 minutes. An intra-aortic infusion of saline (control), mannitol, dopamine, or mannitol plus dopamine was started before, and continued during, the period of aortic occlusion. Glomerular filtration rate was significantly depressed 60 minutes after clamp release, and although there was some recovery in treated animals 150 minutes after clamp release, it remained significantly decreased (52% to 73% of baseline values, p less than 0.01). Renal blood flow was significantly reduced 60 minutes after clamp release, and there was no recovery in any group at 150 minutes (38% to 56% of baseline values, p less than 0.01). No significant differences in osmolar clearance or fractional excretion of sodium were evident between groups. These data reveal that the profound reductions in glomerular filtration and renal blood flow induced by thoracic aortic cross-clamping were not attenuated by mannitol or dopamine and suggest that efforts to protect renal function should be directed toward improving renal blood flow in the post-clamp period.

Mediastinal carinal bronchogenic cyst: is its mere presence an indication for surgical excision?

A notion has prevailed that carinal bronchogenic cyst and other congenital mediastinal cystic lesions, particularly those occurring in older children and adults, are usually asymptomatic, innocuous, and frequently only an incidental finding on routine chest roentgenogram or postmortem examination. Some physicians, therefore, have adopted a policy of observation for these patients. Our experience, however, as demonstrated in three cases reported herein, and the experience of others, clearly shows that carinal bronchogenic cyst is far from being usually asymptomatic and innocuous, but in fact often produces a broad spectrum of clinical manifestations, some of which are life-threatening. Mere observation not only places these patients at serious risk, but also increases the possibility of missed diagnosis and delayed treatment of those lymphoproliferative malignancies involving mediastinal lymph nodes that can mimic a carinal bronchogenic cyst. Computerized tomography (CT) is the single most important method of making a diagnosis of carinal bronchogenic cyst. We believe strongly that the mere presence of a mediastinal carinal bronchogenic cyst is an indication for surgical excision.

Management of esophageal gunshot wounds.

The records of 20 patients with gunshot wounds of the esophagus seen from 1973 through 1985 were reviewed. Nine perforations were cervical, 10 were thoracic, and 1 was abdominal. Because physical findings and plain roentgenograms lack specificity, a high index of suspicion based on the path of the bullet tract is essential for early diagnosis. Esophageal injury should especially be suspected when the bullet wound is transcervical or transmediastinal. Perforation was diagnosed by esophagoscopy in 9 patients, esophagography in 4, and surgical exploration in 7. Mean time from admission to operation was 3.8 hours. Associated injuries occurred frequently. Eighteen patients were treated by primary closure and wide drainage, and 2 were managed by esophageal exclusion. There were 2 perioperative deaths, both in patients with associated aortic injuries, and 1 late death, for an overall mortality of 15%. There was one postoperative leak following a cervical repair. No leaks occurred in patients having a thoracic repair. The findings indicate that esophageal perforation must be sought by a variety of methods. With prompt diagnosis and early operation, primary repair can be safely accomplished. When sepsis from esophageal leak is avoided, mortality and major morbidity are related to associated injuries.

Blunt traumatic rupture of the right hemidiaphragm: experience in 12 patients.

In a 9-year period (1972 to 1981), 35 patients with blunt traumatic rupture of the diaphragm were seen in our institution; 12 had involvement of the right hemidiaphragm, an incidence of approximately 34%. In 9 of these 12 patients, the right-sided diaphragmatic injuries were seen soon after the accident (acute), and in 3, late after the accident (chronic). A large diaphragmatic rent, usually 10 cm or more, without any predilection to a specific area of the right hemidiaphragm, was a frequent operative finding. Expectedly, the most common viscus that was injured or herniated through the defect was the liver. Total or nearly total herniation of the liver was noted in 5 patients and partial herniation, in 1. Injury to the juxtahepatic vena cava or hepatic vein, or both, was also encountered in 5 patients. This highly lethal injury accounted for the 3 deaths in the series, all of which were directly related to an uncontrollable exsanguinating hemorrhage from the injured vena cava or hepatic vein. The surgical approach for repair of a ruptured right hemidiaphragm is best individualized. The right thoracotomy approach through a right posterolateral incision is preferred for chronic diaphragmatic injury. It is also our choice in patients in whom acute right-sided injuries are definitively diagnosed and who are hemodynamically stable. This approach not only provided the best exposure of the defect, but also made the repair of associated retrohepatic caval injury surprisingly easy in at least 2 of our patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of acute cardiac trauma.

It is estimated that approximately 165,000 people die of traumatic causes every year. Thoracic trauma accounts for 25 per cent of all these traumatic deaths, and primary cardiac injury is a major contributing cause. Thus, every member of a trauma team must have a thorough knowledge of the diagnosis and management of cardiac injuries--penetrating and blunt--to effect an improvement in the overall survival of this group of trauma patients.

Measurement of aortic root size by biplane angiography before cardiac valve replacement.

Aortic valve replacement (AVR) in the patient with a small aortic root demands special consideration because the hemodynamic function of artificial valves with a small external diameter is often poor. In this study, the internal diameter of the aortic root was measured from biplane ventriculography. This measured root diameter was then used to predict the external diameter of the artificial valve. Twelve patients underwent biplane ventriculography followed by AVR with Carpentier-Edwards bioprostheses. The artificial valve diameter was predicted with a correlation coefficient of 0.93, a standard error of estimate of 0.89 mm, and an average absolute difference between preoperative measurement and valve diameter of 0.69 mm. Therefore, the aortic root diameter can be accurately measured from the ventriculogram, thus detecting the patient with a small aortic root before surgery.