Minute ventilation sensing rate modulated pacemaker reliability, sensitivity, and utility of cardiopulmonary stress test for optimal rate programming

Among the different sensors available to date for rate responsive pacing, the minute ventilation sensor is claimed to be the most physiological. This study aims to verify the reliability, physiological sensitivity and rate modulating ability of minute volume as a sensor for rate responsive pacing, together with the utility of cardiopulmonary stress test [CPX] to optimize pacing rate. In addition, comparison between the cardiac performance during exercise in fixed-rate VVI versus that in rate responsive modes of pacing was studied. We implanted the META MV in 5 patients [3 males and 2 females, mean age 36. 4 +/- 1.6 yrs, NYHA class 1] affected by CHB. These patients were followed for 3-12 months. Treadmill symptoms-limited exercise test was performed for each patient in both adaptive and rate responsive modes using Bruce protocol. Cardiopulmonary parameters were measured on 1-minute interval. During rate responsive mode exercise capacity improved significantly in comparison to UVI adaptive mode: anaerobic threshold [AT] increased from 1.15 +/- 0.13 to 1.34 +/- 0.16 1/min [16.7%; P 0.005]; time of AT increased from 7 +/- 1.9 to 9.8 + 2.14 minutes [40%; P 0.0025]; VO2 max increased from 1.15 +/- 0.17 to 1.7 +/- 0.18 1/min [12.5%; P]. Sensitivity of the sensor determined from the correlation between VO2 and pacing rate was very strong during the maximal incremental Bruce test [mean r value 0.9650 +/- 0.02]. This correlation was also maintained during our laboratory, brief, low and discontinously graded test [mean r value: 0.9338 +/- 0.01]; however, the response was weaker when compared with that of 15 normal controls. In order to identify the optimal pacing rate which is the lowest rate able to attain the best cardiac performance with preservation of liner correlation between VO2 and heart rate - we repeated for each patient the CPX several times with different slope rates. In 3 patients the optimal pacing rate was 1 or 2 slopes less than the suggested one. In one patient, the slope needed to be reduced after 3 months of implantation; this was due 10 improvement of physical fitness. Follow-up confirmed a correct pacing status. Rate responsive pacing improves cardiac performance belter than fixed-rate VVI pacing. The MV sensor is reliable and highly sensitive, but has poor rate modulating ability. The optimal rate response is not always that suggested by Adaptive mode; moreover, it may change with time. The CPX is mandatory to program and properly follow-up the patients

use of a brain imager electroencephalograph in carotid and cardiac surgery

The use of standard electroencephalogram [EEG] during anesthesia is limited by difficulties with both the application and maintenance of scalp electrodes, and the interpretation of the large body of data generated. These problems have limited the routine use of the EEG during surgeries of high risk of neurological damage. The use of computer assisted analysis of the EEG can assist rapid and comprehensive interpretation of the EEG. This study reported the initial experience with one such system. An electrode cap, adjusted to the size of the patient's head, was used to monitor 32 channels of EEG waveform in real time. The analyzed EEG is then displayed as a continuously upgraded color map with a number of alternate displays. This system has now been used in 23 patients during open cardiac surgery or carotid artery surgery. More importantly, ischemic changes in the EEG have been recognized during times of high risk during carotid artery surgery. However, even in patients exhibiting clear ischemic changes on the analyzed EEG, no changes in postoperative neurological examination were observed

Management of carotid-cavernous fistulas by muscle embolization

The most radical and effective treatment of carotidocavernous fistulae consists of isolation of the cavernous portion of the internal carotid artery. Ligation in the neck after intracranial clipping of its supraclinoid portion could be used. Recently intravascular detachable balloon occlusion was used. These procedures have their hazards and are associated with high morbidity. This report describes eight cases of carotidocavernous fistulae successfully obliterated by muscle embolization. This eliminates the need for craniotomy and sophisticated radiologic equipment. Its simplicity made it an accepted alternative in treating this condition, especially in developing countries

Non-discogenic, extradural lumbosacral spinal compression

25 patients with non-discogenic extradural lumbosacral compression were studied and analysed. Spinal secondaries constituted 28% of the cases. T.B. constituted 24%, while 20% were due to post traumatic fracture spine and 8% were caused by chronic granulomatous lesion. Clinical picture and plain X-ray had a big role in diagnosis of most of the cases. Myelography had a major role in diagnosis, localisation of the site of the lesion, its extent and its relation to the nervous structures and the dura