Francis C. Wells

Impairment of endothelium-dependent pulmonary-artery relaxation in chronic obstructive lung disease

BACKGROUND Endothelial cells release endothelium-derived relaxing factor (EDRF) in a variety of vascular beds, including the pulmonary circulation. However, the role of EDRF-mediated pulmonary-artery relaxation in chronic hypoxic lung disease is unknown. METHODS We studied endothelium-dependent relaxation mediated by EDRF in vitro in pulmonary arteries that had been obtained from 22 patients undergoing heart-lung transplantation for end-stage chronic obstructive lung disease. Control pulmonary arteries were obtained from 15 patients undergoing lobectomy for lung carcinoma who did not have evidence of other chronic lung disease. The responses of all vascular rings (external diameter, 1.2 to 3.4 mm) to the endothelium-dependent vasodilators acetylcholine and adenosine diphosphate were studied immediately after lung excision. RESULTS Pulmonary arterial rings from the patients with chronic lung disease developed a greater tension (2.19 +/- 0.16 g) in response to phenylephrine (10(-6) M) than the rings from control patients (1.28 +/- 0.18 g, P less than 0.05). Inhibition of EDRF synthesis by treatment with NG-monomethyl-L-arginine (10(-4) M) eliminated this difference, increasing the tension in the rings from the controls (P less than 0.01) but not in those from the patients with chronic lung disease. Rings from control patients relaxed in response to cumulative doses (10(-10) to 10(-5) M) of acetylcholine (maximal relaxation, 81.3 +/- 3.9 percent) and adenosine diphosphate (maximal relaxation, 85.3 +/- 2.6 percent). By contrast, rings from patients with chronic obstructive lung disease achieved only 41.3 +/- 4.8 percent of maximal relaxation in response to acetylcholine (n = 32) and 49.4 +/- 5.5 percent in response to adenosine diphosphate (n = 24) (P less than 0.001, as compared with control rings). Rings from both the controls and the patients with chronic lung disease relaxed similarly in response to the endothelium-independent vasodilator sodium nitroprusside (10(-4) M). There was an inverse correlation between the degree of intimal thickening and the level of maximal relaxation of the rings from the patients with chronic lung disease (r = -0.60, P less than 0.001). Maximal relaxation was also related directly to the partial pressure of arterial oxygen before transplantation (r = 0.68, P less than 0.01) and inversely to the partial pressure of arterial carbon dioxide before transplantation (r = -0.55, P less than 0.01), but not to the forced expiratory volume in one second (r = 0.19, P not significant). CONCLUSIONS Endothelium-dependent pulmonary-artery relaxation in vitro is impaired in arteries from patients with end-stage chronic obstructive lung disease. Such impairment may contribute to the development of pulmonary hypertension in chronic hypoxic lung disease.

Cardiopulmonary exercise tests and lung cancer surgical outcome

STUDY OBJECTIVES Surgical resection remains the treatment of choice for anatomically resectable non-small cell lung cancer. However, the presence of associated comorbid conditions increases the risk of death and surgical complications. Several studies have evaluated the usefulness of preoperative exercise testing for predicting postoperative morbidity and mortality. The aim of this study was to establish whether exercise testing could predict poor surgical outcome in lung cancer surgery and whether the absolute value or percentage of predicted value is the better predictor of the surgical outcome. DESIGN The study was designed as a prospective study. PATIENTS AND SETTING One hundred thirty patients with potentially operable lung cancer at Papworth Hospital over 2 years were recruited; of these, 101 underwent curative surgery. INTERVENTIONS Spirometry and cardiopulmonary exercise tests were performed for every patient (n = 99), except for two patients with back problems. We also recorded the outcome of surgery, in particular, complications and mortality. MEASUREMENTS AND RESULTS Mean maximum oxygen transport at peak exercise (Vo(2)peak) was 18.3 mL/kg/min (SD, 4.7 mL/kg/min), and mean percentage of predicted Vo(2)peak value was 84.4% (SD, 30%). Poor surgical outcome was significantly related to Vo(2)peak percentage of predicted (p < 0.01) but not to the actual oxygen uptake value. CONCLUSIONS The use of the percentage of predicted Vo(2)peak value would be a better indicator of surgical outcome, since it predicts the surgical outcome better, and corrects for normal physiologic ranges. The threshold of Vo(2)peak for surgical intervention could be set between 50% and 60% of predicted without excess surgical mortality.

Importance of Subvalvular Preservation and Early Operation in Mitral Valve Surgery

BACKGROUND Mitral valve replacement (MVR) has a high mortality and morbidity. It has been suggested that preservation of the subvalvular apparatus and more optimal timing of surgery might improve outcome. METHODS AND RESULTS We performed a retrospective study of 612 consecutive patients who underwent mitral valve repair or replacement: 226 patients had repair, 68 had replacement with subvalvular preservation (MVR/SVP), and 318 had replacement without subvalvular preservation (MVR/NoSVP). Baseline characteristics were most unfavorable in the repair group with respect to age (P = .002) and in the repair and MVR/SVP groups with respect to NYHA functional class and left ventricular function (P = .044). Thirty-day mortality was lower in the repair (1.8%, P = .046) and MVR/SVP (1.5%. P = NS) groups than the MVR/NoSVP group (5.0%). Overall survival at 7 years was better in the repair (71.2 +/- 5.6%. P = .022) and MVR/SVP (66.2 +/- 12.4%, P = .017) groups than the MVR/NoSVP group (63.5 +/- 3.4%). Myocardial failure caused 66 of 107 complication-related deaths. Multivariate analysis confirmed independent beneficial effects of repair on 30-day mortality (odds ratio, 0.27, P < .05) and of repair and MVR/SVP on overall mortality (hazard ratios, 0.43, P < .001 and 0.40, P < .05, respectively) and complication-related death hazard ratios, 0.38, P < .001 and 0.35, P < .05, respectively). Preoperative NYHA class III or IV symptoms and left ventricular impairment were independent risk factors for death and myocardial failure. CONCLUSIONS Mitral valve repair is superior to replacement. If repair is not feasible, the subvalvular apparatus should be preserved. Early surgery before the development of severe symptoms and demonstrable left ventricular impairment is also needed to optimize outcome.

A Novel Titanium Rib Bridge System for Chest Wall Reconstruction

Chest wall resection for liposarcoma was performed. To reconstruct the chest wall we used a novel titanium rib bridge system and preserved anatomically equivalent layers.

Preservation of the mitral valve apparatus: evidence synthesis and critical reappraisal of surgical techniques

Sub-valvular apparatus preservation after mitral valve replacement is not a new concept, yet to date there has been no quantification of its clinical effectiveness as a procedure and no consensus as to which surgical preservation technique should be adopted to achieve the best immediate and midterm clinical outcomes. This systematic review of current available literature aims to use an evidence synthesis and meta-analytic approach to compare outcomes following replacement of the mitral valve with (MVR-P) or without preservation (MVR-NP) of its apparatus. It considers all the relevant anatomical, experimental, echocardiographic, and clinical studies published in the literature and appraises all reported mitral valve sub-valvular apparatus preservation techniques. The results of this review strongly suggest that MVR-P is superior to MVR-NP with regards to the incidence of early postoperative low-cardiac output requiring inotropic support, and early or mid-term survival. They also suggest that the operative decision should be individualised based on patients anatomy, pathology and ventricular function and therefore surgeons should be familiar with more than one surgical preservation technique. Finally, this paper highlights the need for further high quality research focusing particularly on the long-term assessment of quality of life and health utility following MVR-P.

Phrenic Nerve Stimulation for Central Ventilatory Failure with Bipolar and Four‐Pole Electrode Systems

A multi‐channel phrenic nerve stimulator developed in Tampere has been implanted into seven patients with C2‐etraplegia and into three patients with central sleep apneas. Six bipolar cuff electrodes were implanted bilaterally into the neck. Two four‐pole cuff and 14 four‐pole noncuff electrodes were used in seven patients and to replace one bipolar electrode. Four‐pole electrodes were implanted within the thorax. Seven patients achieved total independence from conventional ventilators within 4 months of implantation, and one for 18 hours each day. Two patients died 12 days and 3 months after implantation and two patients after having achieved independence from mechanical ventilators from causes unrelated to the simulators. Reoperations were necessary because of dislocation of receivers, electrodes, electrode lesions, nerve injuries, and technical failures in seven patients. Most of the problems appeared in two patients with obesity and in three patients with very thin phrenic nerves. Single unit prototypes failed technically more frequently than units of prototype serial fabrication. New electrode design, progress in the manufacture of receivers, and improved implantation technique should help to diminish failures in future.

Pleural effusions: is thoracoscopy a reliable investigation? A retrospective review

In this paper, we consider the results of thoracoscopy in a busy thoracic unit where the referring physicians place their greatest emphasis upon simple standard investigation of pleural disease. Between 1985 and 1989 620 patients with a pleural effusion of unknown aetiology were referred to our thoracic medical unit. Initial investigations included aspiration of pleural fluid for cytology and culture, and blind pleural biopsy for histological examination. Recourse to thoracoscopy was only taken in the absence of a diagnosis or non-resolution of the patients symptoms and signs. Of these 620 patients only 48 (8%) remained without a diagnosis and were referred for thoracoscopy. Histological assessment of biopsies obtained at thoracoscopy revealed malignancy in 24 patients (50%) and benign conditions in 16 patients (33%). In eight patients (17%) no conclusive diagnosis was established; in this latter group, six patients continued with their symptoms and further invasive investigations revealed malignancy. In this setting where thoracoscopy was used as a last resort, the sensitivity for thoracoscopy was 83% and the specificity was 100% with a predictive value of a negative result being 25%. In conclusion, from our experience, the majority of pleural disease may be diagnosed using simple techniques but thoracoscopy can be very helpful in the more complex cases. Moreover, inconclusive histology following thoracoscopy is an indication for further investigation if the condition does not improve.

Morbidity following coronary artery revascularisation with the internal mammary artery.

To investigate the morbidity after coronary artery bypass grafting, one hundred and seventy-eight patients were retrospectively studied with a minimum follow-up period of one year. Although there was no difference in the incidence and distribution of pain in hospital, seventy percent of patients who had an internal mammary artery used as one of the bypass conduits experienced chest wound pain after discharge from hospital compared to 51.7% of patients who had vein grafts alone (P less than 0.05). Twenty-three percent of patients who had left internal mammary arteries harvested experienced chronic left-sided chest wall pain compared to 4.5% of patients who had vein grafts only (P less than 0.005). The possible factors responsible are discussed and a review made of the complications which may result from using the internal mammary artery in coronary artery surgery.

Ventilation-perfusion scintigraphy to predict postoperative pulmonary function in lung cancer patients undergoing pneumonectomy

OBJECTIVE The American College of Chest Physicians (ACCP) recommends using quantitative perfusion scintigraphy to predict postoperative lung function in lung cancer patients with borderline pulmonary function tests who will undergo pneumonectomy. However, previous scintigraphic data were gathered on small cohorts more than a decade ago, when surgical populations were significantly different with respect to age and sex compared with typical lung cancer patients undergoing pneumonectomy in 2005. We therefore revisited the use of V/Q scintigraphy in pneumonectomy patients in predicting postoperative pulmonary function and the appropriateness of current clinical guidelines. CONCLUSION Contrary to ACCP guidelines, we found that ventilation scintigraphy alone provided the best correlation between the predicted and actual postoperative values and recommend its use to predict postoperative lung function. However, scintigraphic techniques may underestimate postoperative lung function, so caution is required before unnecessarily preventing a patient from undergoing surgery that offers a potential cure.

Conservative surgical treatment of valvular injury after blunt chest trauma

BACKGROUND Blunt injury to the cardiac valves leads to progressive ventricular failure often requiring surgical management. Most frequently, prosthetic replacement is the chosen management. METHODS Three consecutive patients presenting to one surgeon with blunt traumatic valve lesions formed the study group. RESULTS At operation, the valvular pathology was assessed, and reparative techniques were used to correct the defects. All the patients had an excellent outcome at follow-up periods of 2 to 3 years. CONCLUSIONS Conservative operation to repair traumatic valve lesions is feasible and has potential advantages over replacement.