The history of thoracoscopic surgery.

The necessity for thoracoscopy became apparent with the adhesions that limited the success of Forlanini's introduction in 1882 of artificial pneumothorax in the treatment of pulmonary tuberculosis. The first thoracoscopy, using a modified cystoscope, was performed by H. C. Jacobaeus, a professor of medicine, not surgery, in Stockholm, publishing in 1910. Thoracoscopy and division of adhesions (intrapleural pneumonolysis) then spread all over the world, with reports of series of 1,000 or more cases in spite of a significant incidence of complications. Its use declined rapidly after the introduction of streptomycin in 1945, becoming then confined to relatively minor diagnostic procedures except in a few European centers. The advent of video-assisted thoracoscopes and the development of ancillary instruments has allowed a new explosion of thoracoscopic surgery. Surgeons, in whose hands the procedure now rests, should nevertheless be aware of the five unacceptable thoracoscopic disasters--wrong side, kebab lung, "clotted hemothorax," artificial lunchothorax, and aorto-pleuro-cutaneous fistula.

Transient hypocalcemic reperfusion does not improve postischemic recovery in the rat heart after preservation with St. Thomas' Hospital cardioplegic solution.

We used the isolated perfused working rat heart to investigate the effects of transient hypocalcemic reperfusion after cardioplegic arrest with the St. Thomas' Hospital cardioplegic solution and 25 minutes of global normothermic (37 degrees C) ischemia. Hearts were reperfused (Langendorff mode) transiently (20 minutes) with solutions containing various concentrations of calcium; this was followed by 30 minutes of reperfusion with standard (1.4 mmol/L, the physiologic concentration) calcium buffer (10 minutes in the Langendorff mode and 20 minutes in the working mode). Recovery of cardiac output in control hearts (calcium concentration 1.4 mmol/L throughout) was 51.7% +/- 4.6%; in hearts transiently reperfused with hypocalcemic buffer (0.25, 0.5, 0.75, or 1.0 mmol/L) the recoveries of cardiac output were 49.3% +/- 6.4%, 52.2% +/- 7.2%, 58.7% +/- 3.2%, and 47.2 +/- 4.7%, respectively (all not significant), whereas recovery was only 14.7% +/- 2.8% (p less than 0.05) in hearts transiently reperfused with calcium 0.1 mmol/L. Creatine kinase leakage was significantly (p less than 0.05) greater in the group reperfused with calcium 0.1 mmol/L, but it did not vary significantly between the other groups. Tissue high-energy phosphate content was similar and in the normal range in all groups except for the group reperfused with calcium 0.1 mmol/L. In further experiments, the duration of hypocalcemic (0.5 mmol/L) reperfusion was varied (0, 5, 10, 15, 20, or 30 minutes). No significant differences in recovery of cardiac output were observed (58.2% +/- 5.0%, 52.3% +/- 5.7%, 52.0% +/- 8.2%, 61.2% +/- 5.0%, 62.2% +/- 4.3%, and 66.2% +/- 3.2%, respectively). In additional studies, the standard calcium concentration (1.4 mmol/L) used before and after ischemia was replaced by hypercalcemic solution (2.5 mmol/L). Despite this, transient (10 minutes) hypocalcemic (0.5 mmol/L) reperfusion did not improve recovery. Finally, studies were undertaken with a longer duration of ischemia (40 minutes), and although recovery of cardiac output in the hypocalcemic group (0.5 mmol/L for 10 minutes) tended to be higher than in the control group (29.7% +/- 4.8% versus 18.5% +/- 4.9%, respectively), statistical significance was not achieved. We conclude that in these studies transient hypocalcemic reperfusion did not afford any additional protection over and above that afforded by cardioplegia alone.

Perfusate calcium: effect on cardiac stability and response to ischemia and reperfusion.

OBJECTIVE: The aim of this study was to characterize the relationship of perfusate calcium concentration, contractile state and stability of the isolated crystalloid perfused working rat heart preparation, to ischemic duration and functional recovery, at a physiological perfusate calcium concentration. METHODS AND RESULTS: In the first protocol, hearts (n = 6 per group) were aerobically perfused for up to 300 mins with Krebs Henseleit solution containing calcium concentrations (total) of 1.0, 1.2, 1.4, 1.6, 1.8 and 2.5 mmol/L (equivalent to ionized concentrations of 0.76, 0.94, 1.15, 1.21, 1.58 and 2.25 mmol/L, respectively). After 120 mins, aortic flow decreased by less than 20% in all preparations except those perfused with 1.0 mmol/L, which fell by over 60%. For subsequent studies, a calcium concentration of 1.4 mmol/L (ionized calcium 1.15 mmol/L, a value equivalent to plasma ionized calcium) was identified as ideal and shown to be associated with stable function and adequate inotropic reserve. The second protocol was as follows: In additional studies (n = 6 per group), the relationship between normothermic global ischemic duration (with or without cardioplegic arrest) and post ischemic functional recovery was characterized. Increasing the ischemic duration (10, 15, 20, 25, 30, 35 or 40 mins) progressively impaired recovery of aortic flow to 86.7 +/- 3.2%, 71.7 +/- 4.9%, 27.7 +/- 5.0%, 14.5 +/- 12.3%, 0%, 0% and 0%, respectively, in the noncardioplegia group, and to 84.7 +/- 1.7%, 85.0 +/- 2.9%, 78.0 +/- 2.4%, 56.0 +/- 7.8%, 32.2 +/- 6.0%, 6.5 +/- 3.7% and 0%, respectively, in the cardioplegia group. These results were similar to those of previous studies in which 2.5 mmol/L calcium was used in the perfusate. CONCLUSIONS: Perfusion of isolated hearts with perfusate calcium concentrations up to 2.5 mmol/L (total) had no apparent detrimental effect on the stability of the preparation; however, a calcium concentration of 1.0 mmol/L resulted in a rapidly deteriorating preparation. In addition, under the conditions prevailing in the present study, a perfusate calcium content within the physiological range (1.4 mmol/L) appeared not to alter the vulnerability of the rat heart to injury during ischemia and reperfusion.

Long-term preservation of the mammalian myocardium. Effect of storage medium and temperature on the vulnerability to tissue injury.

Human heart preservation for transplantation commonly involves infusion of cold cardioplegic solutions and subsequent immersion in the same solution. The objectives of the present study were (1) to establish the temporal relationship between storage time (at 10 degrees C) and the postischemic recovery of function in the isolated rat heart, (2) to assess, by metabolic and functional measurements, whether storing the heart in fluid as opposed to moist air had any effect on the viability of the preparation, and (3) to ascertain the optimal storage temperature. Isolated rat hearts (at least 6 in each group) were infused for 3 minutes with St. Thomas' Hospital cardioplegic solution No. 2 at 10 degrees C, stored at 10 degrees C for 6, 12, 18, or 24 hours, and then reperfused at 37 degrees C. Mechanical function, assessed by construction of pressure-volume curves (balloon volumes: 20, 40, 60, 80, 100, and 120 microliters), was measured before ischemia and storage and after 60 minutes of reperfusion. Function deteriorated in a time-dependent manner; thus at a balloon volume of 60 microliters the recovery of left ventricular developed pressure was 84.2% +/- 5.3% after 6 hours (p = not significant when compared with preischemic control); 69.1 +/- 3.3% after 12 hours (p less than 0.05); 55.6% +/- 4.4% after 18 hours (p less than 0.05), and 53.0% +/- 6.8% (p less than 0.05) after 24 hours of storage. Other indices of cardiac function, together with creatine kinase leakage and high-energy phosphate content, supported these observations. Since the recovery of the left ventricular developed pressure balloon volume curves were essentially flat after 18 and 24 hours of storage, either 6 or 12 hours of storage were therefore used in subsequent studies. Comparison of storage environment (hearts either immersed in St. Thomas Hospital cardioplegic solution No. 2 or suspended in moist air at 10 degrees C for 6 or 12 hours) revealed no significant differences in functional recovery between the groups. Thus hearts recovered 94.9% +/- 3.5% and 113.7% +/- 12.4%, respectively, after 6 hours of storage and 71.6% +/- 2.4% and 54.2% +/- 7.9%, respectively, after 12 hours of storage. Enzyme leakage and tissue water gain were also similar in both groups of hearts. Finally, hearts (n = 6 per group) were subjected to 12 hours' storage at 1.0 degree, 5.0 degrees, 7.5 degrees, 10.0 degrees, 12.5 degrees, 15.0 degrees, and 20.0 degrees C.(ABSTRACT TRUNCATED AT 400 WORDS)

Thoracoscopic debridement and pleural irrigation in the management of empyema thoracis.

As a sequel to a paper reporting good results obtained in 12 patients with empyema thoracis treated by thoracoscopic debridement and irrigation in our department, subsequent experience with a further 18 patients is reported. Drainage of pus and irrigation resulted in resolution of pyrexia with improvement in general condition in all patients. Overall, complete resolution was obtained by this technique alone in 60% (18/30). Of the 12 patients in whom complete resolution was not obtained, secondary surgical measures resulted in resolution of empyema in 8. Four patients died; all were elderly and severely debilitated, 3 with advanced malignancy. Their deaths were not related to the technique, which was well tolerated in all cases. Thoracoscopic debridement and irrigation used routinely as a first-line measure in empyema thoracis is a safe and relatively atraumatic procedure, does not exclude the use of any subsequent surgical measure, and provides valuable time to improve the condition of debilitated patients so that they may tolerate more aggressive surgical procedures.

Creatine phosphate (Neoton) as an additive to St. Thomas' Hospital cardioplegic solution (Plegisol). Results of a clinical study.

Experimentally, creatine phosphate (CP) added to St. Thomas' Hospital cardioplegic solution (STH) improved post-ischaemic recovery of cardiac function in the rat heart. We investigated the effect of adding CP (10.0 mmol/l) to STH. Fifty open-heart surgery patients were randomized into control (STH) and treated (STH + CP) groups (25 per group). Patients underwent (a) monitoring for peri- and postoperative arrhythmias (48-h Holter monitoring). (b) quantitative birefringence assessment of intraoperative myocardial protection in left and right ventricular biopsies sampled at start of bypass (pre-isch.), end of bypass (end-isch.) and after 10 min reperfusion (post-isch.), and (c) measurement of serum creatine kinase-MB isozyme (CK-MB) values for up to 4 days postoperatively; results were assessed with respect to (d) haemodynamics and postoperative clinical outcome. Inotropic support (adrenaline) was required in three patients (12%) from each group; no patient died. All patients required defibrillation, and the number of direct current shocks required for sinus rhythm was the same in each group. The occurrence and incidence of reperfusion-induced arrhythmias were the same in both groups. Serum CK and CK-MB values were similar throughout the sampling period in both groups of patients; one patient in the control group had raised CK-MB levels postoperatively, but perioperative infarction was not indicated by the electrocardiogram.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary sarcoma of the lung: potential dangers of immunocytochemistry.

A case is presented of a successfully resected primary pulmonary sarcoma in a 27-year-old man, followed by an eight-year disease-free follow-up. Details of the histological findings are presented, and the factors associated with good prognosis discussed. Immunocytochemical stains were carried out this year when the case was reviewed, and not at the time of resection. Had the immunostains been available at the time, the results would have suggested that the tumour might be a secondary deposit, and so have caused needless anxiety to the patient and his physicians.

Harvesting hearts for long-term preservation. Detrimental effects of initial hypothermic infusion of cardioplegic solutions.

Current procedure for harvesting human donor hearts for long-term storage before transplantation involves direct infusion of a hypothermic (4 degrees C) crystalloid cardioplegic solution into the normothermic (37 degrees C) heart in situ. We used the isolated perfused working rat heart preparation to investigate whether infusing cold crystalloid solutions into normothermic blood-containing hearts was consistent with maximal myocardial protection. Hearts (n = 6 per group) were excised and subjected to a primary (1 minute) infusion with either the St. Thomas' Hospital cardioplegic solution or a bicarbonate buffer solution, at 7.5 degrees C, 22 degrees C, or 37 degrees C. This was followed by a secondary infusion (2 minutes) with cold (7.5 degrees C) cardioplegic solution, after which all hearts were stored at 7.5 degrees C for 6 hours and then reperfused at 37 degrees C for 60 minutes, during which time creatine kinase leakage and cardiac function were measured. Primary infusion with warm solutions resulted in (1) decreased coronary vascular resistance during cardioplegic infusion and (2) greater postischemic cardiac function. This suggests that their use, before the standard cold infusion, might be beneficial to the long-term preservation of transplant donor hearts.

Comparison of standard (non-oxygenated) vs. oxygenated St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol).

Recent studies have suggested that oxygenation of crystalloid cardioplegic solutions improves myocardial preservation. To assess whether oxygenation of St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol) improves its clinical efficacy, 50 patients were randomly assigned into 2 groups: (1) those receiving Plegisol and (2) those receiving O2-Plegisol (PO2 greater than 500 mmHg at 4 degrees C). Efficacy was assessed by (a) clinical and haemodynamic parameters, (b) quantitative birefringence changes in response to ATP and calcium as a measurement of myocardial preservation in left and right ventricular biopsies, (c) creatine kinase (MB isoenzyme) release for up to 4 days postoperatively, (d) electrocardiographic (ECG) monitoring for up to 7 days postoperatively. There were no differences in mean age, ejection fraction, aortic cross-clamp duration, or bypass duration between the 2 groups of patients. In the Plegisol group, 2 patients (8%) died and 4 patients (16%) required inotropic support, whereas in the O2-Plegisol group there were no deaths and only 2 patients (8%) required inotropic support. These differences, however, were not statistically significant. Birefringence assessment demonstrated an improved myocardial response to ATP and calcium (predominantly in the left ventricular epimyocardium and in the right ventricular biopsies) at the end of ischaemia and after reperfusion in patients given O2-Plegisol. Deterioration in cellular assessment of myocardial contractility (measured by a reduction in birefringence of greater than 0.4 nm) was reduced from 20% in Plegisol patients to 12.5% in O2-Plegisol patients. CK-MB values showed no difference at any sampling time between the 2 groups of patients; a mean peak CK-MB of 35 IU/l occurred 2 h postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

The management of empyema thoracis by thoracoscopy and irrigation.

A technique of irrigation for the management of empyema thoracis is described. Initial thoracoscopy using a laparoscope under general anaesthesia enabled adequate debridement and breakdown of loculi within the empyema cavity under direct vision. Following this procedure irrigation of the cavity with two tubes was started and continued until three consecutive cultures of drained irrigation fluid became sterile. The procedure was then discontinued. The results in 14 patients are presented using this method, irrigation was required for an average of 14 days. Patients remained in hospital for an average of 4.8 weeks. Tuberculous empyema was not found to be a contra-indication to the irrigation technique.

Reperfusion-induced arrhythmias in the conscious rat: a comparative study with three calcium antagonists.

The effects of three calcium antagonists (diltiazem, verapamil, and nifedipine) on reperfusion-induced arrhythmias were compared in a conscious rat preparation with coronary artery occlusion and implanted electrocardiogram limb electrodes. Upon reperfusion after a 5-min period of occlusion, all (15/15) untreated control rats exhibited immediate ventricular tachycardia, which rapidly deteriorated to ventricular fibrillation; 87% (13/15) of the rats died as a consequence of these rhythm disturbances. In the groups treated with calcium antagonists, each drug (diltiazem, verapamil, or nifedipine) was given as an intravenous bolus 10 min prior to coronary occlusion (n = 12 in each group). The incidence of ventricular fibrillation was significantly reduced by all three calcium antagonists and this antifibrillatory effect resulted in a significantly lower mortality in all drug-treated groups. With diltiazem (0.5 and 2.0 mg/kg) mortality fell from 87 to 42% (P less than 0.05) and 35% (P less than 0.01), respectively; with verapamil (0.5 and 5.0 mg/kg) it fell to 25% (P less than 0.01) and 0% (P less than 0.001); and with nifedipine (5.0 and 50 micrograms/kg), it fell to 25% (P less than 0.01) and 8% (P less than 0.001). At a dose of 5.0 mg/kg, verapamil caused a large reduction in heart rate both prior to and during coronary occlusion and reperfusion; however, with other doses and drugs no significant changes in heart rate were observed. ST segment elevation during the 5-min ischemic period was reduced by pretreatment with all drugs. In conclusion, in the conscious rat, pretreatment with diltiazem, verapamil, or nifedipine affords some protection against reperfusion-induced arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Free radicals and cardioplegia: organic anti-oxidants as additives to the St Thomas' Hospital cardioplegic solution.

The isolated perfused working rat heart model of cardiopulmonary bypass and ischaemic cardiac arrest has been used to investigate whether addition of various organic anti-oxidants to the St Thomas' Hospital cardioplegic solution can enhance the recovery of function of the rat myocardium after normothermic (37 degrees C) global ischaemic arrest. Five anti-oxidants were studied: (i) ascorbate (1.0 and 10.0 mmol.litre-1), (ii) methionine (1.0 and 10.0 mmol.litre-1), (iii) reduced glutathione (1.0 and 10.0 mmol.litre-1), (iv) dimethylthiourea (0.1, 1.0, 10.0 and 50.0 mmol.litre-1), (v) N-2-mercaptopropionyl glycine (0.1, 1.0 and 10.0 mmol.litre-1). The recovery of aortic flow in control hearts which were free of anti-oxidant was 50.7(SEM 0.5)%; ascorbate (1.0 or 10.0 mmol.litre-1) improved this recovery to 72.1(1.7) and 70.2(0.3)% respectively; methionine (1.0 and 10.0 mmol.litre-1) improved the recovery to 74.1(5.7)% and 67.7(1.7)%, respectively; reduced glutathione (1.0 and 10.0 mmol.litre-1) improved the recovery to 66.7(1.4)% and 74.0(1.7)% respectively. In further studies, the addition of dimethylthiourea (0.1, 1.0 and 10.0 mmol.litre-1) to the cardioplegic solution failed to improve recovery of aortic flow [47.3(8.0), 24.6(7.3), 48.0(7.7)% respectively] when compared to its anti-oxidant free control value of 40.4(6.1)% and at a concentration of 50.0 mmol.litre-1 a very poor recovery of aortic flow of 7.7(4.8)% was observed. Mercaptopropionyl glycine (0.1, 1.0 and 10.0 mmol.litre-1) also failed to improve the recovery of aortic flow [34.7(1.6), 34.7(7.7) and 25.6(5.4)% respectively.2+ Since biological membranes are highly permeable to dimethylthiourea and mercaptopropionyl glycine, it is possible that they accumulate in the intracellular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardioplegia: relation of myocardial protection to infusion volume and duration.

Clinically, initial infusion volumes of crystalloid cardioplegic solution are relatively low (500-1000 ml or 2-4 ml/g myocardium) compared to those used experimentally. In particular, rat hearts (in which many clinical solutions have been developed and evaluated) commonly use 20-30 ml/g myocardium (equivalent to 5.0-7.5 l in human heart). We used the isolated working rat heart to characterise the relationships between myocardial protection and (a) infusion duration, and (b) infusion volume of St. Thomas' Hospital cardioplegic solution (STH), Hearts were aerobically perfused (20 min) and subjected to varying durations of STH infusion (0-300 s) prior to normothermic global ischaemia (30 min). During reperfusion, maximal recovery of cardiac output occurred when infusion durations exceeded 30 s and infusion volumes exceeded 5.0 ml/g myocardium. To assess infusion volume rather than duration, hearts were infused with 1.0, 1.5 or 2.0 ml of STH for 120 s. Optimal recovery of cardiac output required 2.0 ml/g myocardium for 120 s. To assess infusion duration with low infusion volumes, 2.0 ml STH/g myocardium was infused for 10, 30, 60 and 120 s; optimal recovery of cardiac output occurred with infusions of 30 s or longer. Thus, even in the rat heart, optimal protection with STH can be achieved by infusion at a volume of 2.0 ml/g myocardium for a duration of not less than 30 s, similar to that now in current clinical use.

Clinical validation of St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol).

Recently, the St. Thomas' Hospital cardioplegic solution No. 2 (Plegisol) has become available commercially in the UK. In a series of patients (n = 28) undergoing open heart surgery for a variety of lesions, a clinical validation was performed. Preservation of myocardial contractility was assessed biophysically by quantitative birefringence measurements of myocardial biopsy samples (full thickness apical left ventricle and right ventricle) taken (1) prior to ischaemia, (2) at the end of ischaemia and (3) 10-15 min after reperfusion during cardiopulmonary bypass. In addition, serum CK-MB values were measured in samples taken throughout the operation and for 4 days postoperatively. Postoperative ECG traces (taken every 6 h for 48 h and then daily up to 7 days) were analysed to identify the occurrence of perioperative infarction. There were no hospital deaths. Chronotropic support was required in 5 of 28 patients (18%) for transient heart block. Low cardiac output did not occur postoperatively. Birefringence measurements in biopsy samples taken at the end of the ischaemic period (immediately prior to reperfusion) indicated an apparent left ventricular deterioration in myocardial contractility in 12 of 28 patients (43%) when compared to biopsies sampled prior to the ischaemic period. However, after 10-15 min of aerobic reperfusion, measurements indicated that myocardial contractility recovered to almost pre-ischaemic levels in the majority of patients. Thus, in 22 of 28 patients (79%), left ventricular deterioration did not occur in post-ischaemic biopsy samples when compared to the pre-ischaemic biopsies. Similarly, 21 of 28 patients (75%) had no deterioration of birefringence values in right ventricular biopsies.(ABSTRACT TRUNCATED AT 250 WORDS)

Ischemia- and reperfusion-induced arrhythmias in conscious rats--studies with prazosin and atenolol.

A conscious rat system has been developed to investigate the ability of alpha- and beta-adrenoceptor blocking agents to modify the severity of ischemia- and reperfusion-induced arrhythmias. Ischemia-induced arrhythmias were studied during a 30 min period of occlusion of the left anterior descending (LAD) coronary artery, and 100% of control animals (n = 24) exhibited ventricular tachycardia and 63% ventricular fibrillation. Beta-adrenoceptor blockade with atenolol (1 mg/kg body weight) significantly reduced the incidence of ventricular fibrillation to 17% (p less than 0.05). In contrast, alpha-adrenoceptor blockade with prazosin (0.01, 0.1 or 1 mg/kg body weight) failed to reduce the incidence of arrhythmias and actually increased mortality. This higher mortality with prazosin was associated with bradyarrhythmias. Administration of atenolol (1 mg/kg body weight) also reduced the incidence of reperfusion-induced ventricular fibrillation after a 5 min period of ischemia from 100% to 58% (p less than 0.05). Prazosin could not be tested due to the high mortality during coronary occlusion. Autopsy studies of hearts from the control, atenolol and prazosin groups indicated that all groups had similar occluded zone volumes. In conclusion, in conscious rats beta-blockade with atenolol reduced the incidence of both ischemia- and reperfusion-induced arrhythmias, whereas alpha-blockade with prazosin at the 3 doses studied failed to exert a protective effect and actually increased mortality.