Surgical treatment of spontaneous pneumothorax by wedge resection without pleurodesis or pleurectomy.

OBJECTIVE: Evaluation of wedge resection of the lung without pleurodesis or pleurectomy as a method of surgical treatment for spontaneous pneumothorax in terms of complications, recurrence rate and postoperative complaints. METHODS: Retrospective study of 132 operations for spontaneous pneumothorax in 120 patients (84 men and 36 women: mean age 34 years, range 14-77) performed between 1974 and 1993. The mean observation time was 84 months (range 6-229) and a 100% follow-up rate of all survivors (97%) was achieved. RESULTS: The indications for surgery were recurrent pneumothorax (52%), persisting air leak during first episode (45%), or hemothorax (3%). Perioperative findings were single bullous disease (86%), 2-3 bullae (6%), diffuse bullous disease (5%) and no bullous disease in 3% of the cases. The overall complication rate was 16% (30-day mortality 1%, reoperation for postoperative bleeding 2%, bronchopneumonia 8%, new pneumothorax during hospital stay 5%). The late recurrence rate (operated lung) was 5%. All recurrences were successfully treated by drainage (n = 3), exsufflation (n = 1) or observation only (n = 3). Reoperation was not necessary. Thirty-seven percent of the patients had postoperative complaints which they associated with the operation. CONCLUSION: Lung resection without pleurodesis or pleurectomy is a simple, safe and effective method of the surgical treatment of spontaneous pneumothorax in terms of complications and recurrence rate in patients with limited bullous disease.

New temporary atrial and ventricular pacing leads for patients after cardiac operations.

We have studied two new temporary pacing leads (Medtronic 6491 and 6492) intended for pacing after cardiac operations. The conductor has stainless steel strands coated with polyethylene connected to a 4' mm2 surface area, stainless steel, smooth, tapered electrode. A soft 4-0 coiled polypropylene fiber served as as fixation mechanism in the heart. The study included 15 children (aged 3 months to 7 years, body weight 4.4 to 20 kg) with a variety of congenital heart defects and 15 adults (aged 45 to 78 years) with coronary artery disease (n = 13) and aortic valve disease (n = 2). A pair of leads each was placed in a bipolar fashion in the right atrial wall and nonsystemic ventricle in the children (median implant duration 12 days) and in the right atrial wall only in the adults (median implant duration 9 days). The atrial current threshold values in children increased from 0.61 +/- 0.34 mA immediately after implant to 2.08 +/- 1.86 mA at explant (p < 0.002). In the adults the threshold values increased from 0.95 +/- 1.44 mA immediately after implant to 2.76 +/- 2.76 mA at explant (p < 0.002). In the ventricle the threshold values increased from 0.38 +/- 0.13 mA immediately after implant to 2.22 +/- 1.63 mA at explant (p < 0.002). Tissue resistance immediately after implant measured 809 +/- 182 omega at explant (children, p = not significant). Corresponding values in adults were 778 +/- 190 omega and 599 +/- 91 omega (p < 0.004). In the ventricle resistances changed from 1019 +/- 143 omega to 876 +/- 137 omega (p < 0.05). P wave amplitudes measured 1.8 +/- 1.5 mV immediately after implant and decreased to 1.6 +/- 1.2 mV at explant (p = not significant, children) and 2.0 +/- 1.3 mV to 1.8 mV (p = not significant, adults). R wave amplitude were 13.1 +/- 3.0 mV immediately after implant and fell to 8.7 +/- 4.5 mV at explant (p < 0.005). Thus, threshold values, tissue resistances, and electrogram and pliable amplitudes assured a safe pacemaker function. The small diameter and pliable texture of these leads provided a smooth surgical handling. They were found particularly suitable in children.

Postoperative Doppler echocardiographic evaluation in different sizes of Medtronic-Hall, Biocor and Carpentier-Edwards S.A.V. prosthetic aortic valves.

Doppler echocardiography was performed on 108 patients 4-15 days after implantation of a Medtronic-Hall, Biocor or Carpentier-Edwards S.A.V. prosthetic aortic valve because of aortic stenosis. Significant correlation was found between the in vitro (maker-declared) and the Doppler-estimated effective prosthetic valve orifice area (r = 0.70, p < 0.01). Doppler-estimated prosthetic valve orifice area, but not transprosthetic blood velocities, discriminated between different sizes of Medtronic-Hall and Biocor valves. The effective orifice area in these valves was 57% of the in vitro area, but in Carpentier-Edwards valves it was only 43%. Transprosthetic blood velocity was inversely related to orifice area in men, but not in women, who also had longer duration of systole and better preservation of systolic left ventricular function. The data suggest that the effective prosthetic valve areas found in patients are significantly smaller than the experimental in vitro areas. Prosthesis size and type, anatomic and hemodynamic variables and gender are important in Doppler estimation of effective valve area.

[Treatment of ventricular tachyarrhythmias with an implantable pacemaker-cardioverter-defibrillator]. / Behandling av ventrikulaere takyarytmier med implanterbar pacemaker-kardioverter-defibrillator.

During the period from November 1989 to January 1992, 17 patients with ventricular tachyarrhythmias received an implantable pacemaker-cardioverter-defibrillator. The material consists of three female and 14 male patients with an age range of 13-66 years, mean 50.8 +/- 16.6 years. 13 patients had coronary artery disease, one cardiomyopathy, one a myocarditis sequela and two primary rhythm disorder. Four patients received epicardial and 13 endocardial electrode systems. The observation period varied from 4-30 months (april 1992), mean 15.2 +/- 8.8 months. 11 out of 17 patients (65%) experienced one or more episodes of tachyarrhythmias which was treated successfully with overdrive pacing (ramp or burst), cardioversion or defibrillation. One patient died of heart failure after an observation period of 13 months. His pacemaker-cardioverter-defibrillator had been activated more than 100 times. Two children, 13 and 15 years, were treated successfully for ventricular fibrillation four and five months after implantation of the device. The actual one year survival is 100%. Assuming that therapy with a device had not taken place, and that the six patients who experienced episodes of ventricular fibrillation died, the hypothetical probability of survival would have been 62.1 +/- 12.3%.

Anesthesiologist-manned helicopters and regionalized extracorporeal circulation facilities: a unique chance in deep hypothermia.

Norway has nine light ambulance helicopters, four heavy sea rescue helicopters and seven ambulance air planes in 24-hours duty spread all over the country. Most are manned with anesthesiologists. Five regional hospitals in all parts of the country, offer facilities for extracorporeal circulation. A case in which a 33 year old woman was found hypothermic at 21 degrees C is presented. She developed ventricular fibrillation at the time of her rescue. She was intubated and received chest compression for 70 minutes until she was rewarmed by extracorporeal circulation. She was discharged without signs of cerebral damage. The decision to bypass less advanced hospitals en route to the regional hospital proved correct in this case, and is suggested as standard procedure in deep hypothermic patients.

Morphologic and morphometric analysis of the mast cells from human heart biopsies.

We have examined mast cell morphology in human papillary muscles obtained from patients subjected to mitral valve replacement. Elongated, metachromatically staining mast cells were found in the connective tissue close to blood vessels and nerves. Electron microscopic examination showed that the most conspicuous features were cytoplasmic granules which displayed a crystalline internal structure and which were surrounded by perigranular membranes. They were composed of a number of coiled electron-dense layers (3 to 4 predominantly) which formed scrolls and gratings. Apart from the crystalline structure, all granules had a dark, uniform matrix. Measurements of crystalline structure periodicity indicated a unimodal distribution around a mean of 85.6 +/- 1.9 A.

Inflammatory reaction as an occlusive mechanism in aortocoronary bypass grafts?

Morphological changes in aortocoronary vein grafts are described in two cases; one dying 5 hours post operatively and the other reoperated 8 months after aortocoronary bypass surgery for graft occlusion. Occlusive thrombi and fibrin deposition on the intimal surface and a focal inflammatory process in the wall of the vein grafts were found in the former. Thrombotic encrustation and organization similar to the manifestations of the thrombogenic theory of atherosclerosis were demonstrated in the latter.

A quantitative study of endothelial cell injury in aorto-coronary vein grafts.

Criteria indicating injury of endothelial cells (craters, protrusion, denudation) in saphenous veins for aorto-coronary bypass grafting have been examined and quantitated by use of light-(LM), scanning electron (SEM) and transmission electron microscopy (TEM). The specimens were fixed either by immersion or under pressure. It was shown that the conventional way of handling saphenous vein grafts prior to implantation results in serious damage of the endothelial lining. The factors responsible are presumed to be hypoxia, manual flushing and distension with isotonic saline for blood removal, control of leakage, and counteracting spasm of the graft. Even samples collected by a "no touch" technique and exposed to a short hypoxic interval sometimes revealed slight injury.

Crater formation and endocytosis in human endothelial cells in vitro.

The formation of craters under in vitro hypoxic conditions in the human venous endothelium was studied by scanning-(SEM) and transmission electron microscopy (TEM). Craters are a result of collapsed intracytoplasmatic vesicles which is probably due to extraction of fluid during processing. Thus craters are thought to be artefacts of preparation. This investigation indicates that fusion of caveolae is involved in intracytoplasmatic vesicle formation. A new quantitative method is described for studying endocytosis. Whole vein wall preparations immersed in isotonic saline (approximately 1 h) revealed reduced endocytotic activity in the luminal plasma membrane (LPM) of endothelial cells compared to the basal plasma membrane (BPM), where the endocytotic activity was increased.

Continuous measurement of aortic blood velocity, after cardiac surgery, by means of an extractable Doppler ultrasound probe.

A new method has been developed for the continuous measurement of aortic blood velocity in patients following cardiac surgery. Using an extractable Doppler ultrasound probe placed on the ascending aorta, the changes in aortic velocity were recorded up to 24 h postoperatively, in 14 patients undergoing coronary bypass surgery. Volume flow rate is calculated from the mean velocity, the diameter of the aorta and the angle between the ultrasound beam and the direction of the blood flow, by means of an analogue flow calculator. Estimation of aortic flow showed a correlation of r = 0.79 with cardiac output measured by a thermodilution technique. The main advantage of the system is that it allows continuous monitoring of cardiac output, as well as short and long-term trend analyses, during the early postoperative period.

Long-term comparison of unipolar and bipolar pacing and sensing, using a new multiprogrammable pacemaker system.

Over a six-month period a comparison was made between uni- and bipolar myocardial stimulation thresholds and R-wave sensitivity in 15 consecutive pacemaker patients. The patients received a new multiprogrammable Cordis 336 A pulse generator, that could be programmed with either uni- or bipolar circuitry. In addition, rate, output, sensitivity and pacing mode could be noninvasively programmed. The occurrence of myopotential interference at different sensitivity levels was also studied. Cordis 325-161 bipolar endocardial leads were used in all patients. In one patient, the current output sometimes had to be programmed higher bipolarly than unipolarly to capture the ventricles, otherwise no differences in threshold were found. Acutely. R-wave sensitivity was superior in 9 patients (60%) in the bipolar mode. Unipolar and bipolar electrograms were equal in 4 (26.7%), whereas unipolar R-wave sensitivity was best in only 2 (13.3%) of the patients. At a six-month follow-up, the same tendency was found. In 5 patients, bipolar sensing was superior to unipolar, while anti- and bipolar sensitivity was equal in the remaining patients. Myopotential inhibition was never seen in the bipolar mode at highest sensitivity (0.8 mV) even during provocative tests (n = 15) or 24-hour Holter monitoring (n = 12). In the unipolar mode, 14/15 patients (93.3%) showed inhibition during provocative tests and 12/12 patients (100%) during monitoring at a programmed sensitivity of 0.8 mV. No patients had myopotential interference at a sensitivity level of 3.5 mV. All patients have their pacemakers programmed in the bipolar mode after six months. This study confirms earlier acute data that the bipolar pacing mode is superior to the unipolar mode for permanent pacemaker therapy.

Bipolar atrial application of a new temporary pacing lead after cardiac operations.

A new temporary pacing lead. Medtronic Model 6400, with a defined electrode surface area of 7.5 mm2, has been clinically and electrophysiologically evaluated during bipolar atrial application in 20 patients after cardiac operations. A silicon disc was used for fixation of the electrodes to the right atrium in 10 patients, and an atrial plication technique was used in the other 10. Myocardial stimulation threshold and resistance were measured throughout the postoperative period. Atrial electrograms were recorded on magnetic tape for computer analysis of amplitudes, slew rates, and signal source impedance. No significant differences (p greater than 0.1) were found in myocardial stimulation threshold between the two fixation modes. During constant-current pacing, median threshold rose from 0.65 mA to 2.3 mA. Stimulation resistance, measured during constant-voltage pacing, fell from 567 to 365 omega, with a subsequent rise to 425 omega before electrode removal. Again no difference was found between silicon disc and plication fixation of the electrodes. P-wave amplitudes were significantly higher with plication than with silicon disc fixation (2.26 versus 0.86 mV, p less than 0.01), as were slew rates (0.34 versus 0.18 V/s, p less than 0.05). Signal source impedance had a magnitude of 6 k omega. The electrodes were used successfully in 12 (60%) of the patients for diagnosis and/or treatment of arrhythmias. We find the new lead well suited for atrial application.

New temporary pacing lead for use after cardiac operations.

A newly designed temporary pacemaker lead (Medtronic Model 6400), which has a solid defined electrode surface area of 7.5 mm2, was compared with a multifilamental stainless steel electrode in common use (Davis & Geck, DG). Thirty-nine patients had both types of electrodes inserted intramyocardially in the right ventricle. A DG electrode fastened to the pericardium served as a reference lead. In addition to the standard Medtronic 7.5 mm2 electrode (n = 11), specially made Medtronic electrodes with areas of 5 mm2 (n = 10), 10 mm2 (n = 10), or 7.5 mm2 with platinum-iridium tips (n = 8) were studied. Measurements of myocardial stimulation threshold and resistance were made in both electrodes throughout the postoperative period. The patients' electrograms were recorded on magnetic tape for computer analysis of amplitudes and slew rates. The Medtronic 7.5 mm2 electrodes showed overall better results than 5 and 10 mm2 leads. Maximum stimulation threshold on the Medtronic 7.5 mm2 electrodes was medium 3.4 mA versus 10 mA on DG electrodes (p less than 0.001). The tissue resistance on Medtronic 7.5 mm2 was almost double than on the Davis & Geck electrodes (median 311 ohms versus 164 ohms on the day of minimum resistance, p less than 0.001). There were no significant differences in electrogram amplitudes between the two electrode types studied (5.52 versus 4.68 mV, p greater than 0.1), but the slew rates were significantly higher on the Medtronic (0.56 versus 0.37 V/sec; p less than 0.01). The new lead is an important innovation in temporary pacemaker lead design compared to the commonly used multifilamental leads.

Estimation of flow in aortocoronary grafts with a pulsed ultrasound Doppler meter.

A newly developed pulsed ultrasound Doppler meter was used for measurement of blood flow in aortocoronary vein grafts during operation. The results were compared with measurements obtained with conventional electromagnetic flowmetry. In 27 grafts, excellent agreement was found between electromagnetic flow probes thoroughly calibrated for varying hematocrit on fresh veins in vitro, and a clip-on type of Doppler probe (r = 0.86). In vitro calibration showed a close correspondence (r = 0.98) with the Doppler technique with no dependency on hematocrit and no need for zero calibration. The use of a conventional electromagnetic flowmeter showed strong dependency on recent calibration, both for saline and for varying hematocrit. Zero-calibration was necessary for every single graft measurement. The application of ultrasound Doppler meters of high quality together with clip-on probes of proper design proved to be superior to electromagnetic flowmetry for intraoperative blood flow measurements.

Acute and chronic pulse-width thresholds in solid versus porous tip electrodes.

Sixty-one patients given programmable pacemakers at initial implantation have been followed for a mean of 18 months (3-42) with non-invasive measurements of myocardial pulse-width threshold. Fifty of the patients had CPI 0505/0522 (Microlith-P/Microthin-PI) pacemakers with either Cordis 322-462 8 mm2 ball tip (n=12), Cordis 322-620 17.5 mm2 (n=23), or CPI 4116 porous tip electrodes (stimulation area 7.5 mm2 and sensing area 50 mm2) (n=15). Eleven patients had Medtronic 5985 (Spectrax-SX) pacemakers with either Medtronic 6907-R 8 mm2 ring tip (n=7), 6907 11 mm2 (n=3) or 6917 myocardial electrodes (area 12 mm2) (n=1). At acute implant, the ball tip and porous tip electrodes had the lowest stimulation thresholds, but the differences were only statistically significant in comparison with the 17.5 mm2 electrode (p less than 0.01). Chronically there were no significant differences between the various electrodes (p greater than 0.1), but the ball tip electrode tended to give best long-term results, and the porous tip electrode the poorest. Thirty-eight of the 61 patients (62.3%) had chronic pulse-width thresholds of 0.1 ms or less at approximately equal to 5 V output, indicating that pulse-width programming is a useful way to conserve battery energy. However, at some stage of the study, six of the patients (9.8%) had a pulse-width threshold of 0.5 ms or more. Pulse width should therefore not be set too narrow in standard nonprogrammable pacemakers.

Chemotherapy of a malignant, metastasizing giant-cell tumor of bone: report of an unusual case and the response to combination chemotherapy.

A 13-year-old girl was treated surgically for a giant-cell tumor of bone originating in the talus and for a recurrence in the distal tibia. She later developed liver and lung metastases and was treated for two years, five months with a combination of vincristine, doxorubicin, cyclophosphamide and actinomycin-D, and thereafter with high-dose methotrexate/vincristine with citrovorum factor rescue. A good response was obtained and the patient is without evidence of disease 12 months after a salvage thoracotomy for residual disease in the left lung. Aspects of this singular case are discussed.

Clinical and electrophysiological properties of a new temporary pacemaker lead after open-heart surgery.

A new temporary pacemaker lead, Medtronic 6400, with a solid defined electrode surface area of 7.5 mm2, has been implanted in 50 patients after open-heart surgery. One electrode was inserted intramyocardially on the right ventricle, while another was placed extracardially and served as a reference lead. Forty-six of the patients were followed postoperatively with measurements of myocardial stimulation threshold and resistance. In 25 of the patients, electrograms were recorded on magnetic tape for further computer analysis of amplitudes, slew rates, and signal source impedance. During constant current pacing, myocardial stimulation threshold increased from a median of 0.4 mA one hour postoperatively to a maximum value of 2.3 mA. In two patients (4.3%) intermittent pacing failure was seen. Stimulation resistance fell from a median of 875 omega to a minimum of 487 omega, with a subsequent increase of 598 omega before electrode removal. Both mean electrogram amplitude (7.35 mV) and slew rate (0.82 V/s) had their minimum values on the sixth postoperative day. Intermittent sensing failure was observed in 2/25 patients (8%). Signal source impedance was of a magnitude not likely to contribute to sensing failure. No complications were seen from the use of this lead. The new electrode is an important improvement in temporary pacemaker lead design.

Electrophysiological properties of a new permanent endocardial lead for uni- and bipolar pacing.

Unipolar and bipolar electrode systems were compared for electrogram amplitudes and slew rates, signal source impedance, and myocardial stimulation threshold and resistance in 15 consecutive patients who received a new endocardial electrode (Cordis 325-161). The bipolar electrograms showed the highest amplitude in nine of the patients (60%). The unipolar and bipolar electrograms were equal in four patients (26.7%), whereas the unipolar electrograms were highest in only two patients (13.3%). The difference in mean amplitude between bipolar (11.1 mV) and unipolar (10.1 mV) electrograms was statistically significant (p 0.05). Mean slew rates were almost equal (1.7 versus 1.6 V/s; p greater than 0.1). The bipolar electrode system always gave somewhat higher signal source impedance than the unipolar system (p 0.001). The current threshold was significantly lower during bipolar pacing (0.59 mA) in constant current pacing mode, than during unipolar pacing (0.65 mA) (p less than 0.05). No significant differences were found during constant voltage pacing. Stimulation resistance was highest in the bipolar electrode system (p less than 0.001). We conclude that the bipolar electrode system is as good as, or better than, the unipolar system both for ventricular sensing and for pacing.

Protective effects of verapamil against isoprenaline- induced mobilization of mitochondrial calcium and cellular lipid droplets in the myocardium.

Calcium level and lipid droplets accumulation is studied in the mouse myocardium of animals receiving a single injection of isoprenaline (ISP), of animals receiving ISP after 4-8 days of pretreatment with verapamil (Isoptin), and, of control animals. The animals are sacrificed 4h after the ISP-injection. Calcium is determined in isolated mitochondria and in whole tissue homogenates by atomic absorption spectrometry. Lipid droplets accumulation is analysed by quantitative stereological technique. Mitochondrial calcium is raised by 65% and calcium of whole tissue homogenates by 21% following ISP stimulation. At the same time, the myocardial fractional volume occupied by lipid droplets in the ISP treated animals increases to 14 times that of control. The ISP stimulated elevation of mitochondrial calcium is reduced by 73% and that of lipid fractional volume by 71% after pretreatment with verapamil. No similar reduction of calcium content is observed in the whole tissue homogenates. These results are discussed in terms of the role of Ca2+ in ISP induced myocardial necrosis.