Whole blood hypercoagulability despite anticoagulation during mechanical cardiac assist.

We report hypercoagulability despite activated partial thromboplastin time (APTT)-guided heparin treatment during Berlin Heart-supported circulation in a 38-year-old man with heart failure for 19 days. The patient was anticoagulated using unfractionated heparin, acetylsalicylic acid and dipyridamole. Contact and tissue factor-activated thromboelastometry revealed increased clot firmness, although anticoagulation assessed by APTT was in accordance with the treatment protocol. Strength of polymerized fibrin was also increased. We saw no clinical signs of thrombosis. Thromboelastometry normalized after heart transplantation. Our results suggest that hypercoagulability is due to excess fibrin formation. Monitoring anticoagulation using APTT may, therefore, be misleading during mechanical cardiac assist.

Magnetic resonance imaging angiography in patency evaluation of bronchial artery revascularization grafts.

In this report we present our experience of non-invasive magnetic resonance imaging (MR) angiography and selective catheter angiography in assessing the patency of bronchial artery revascularization grafts after an en bloc double-lung and heart-lung transplantation. We studied 8 patients who had undergone pulmonary transplantation with direct bronchial artery revascularization. Catheter angiography was performed 10 days to 63 months postoperatively. MR angiography was performed within 24 h of the catheter procedure and the results were compared with the findings from catheter angiography. Catheter angiography showed the bronchial revascularization graft to be patent in 6 patients and occluded in 2. At MR angiography, the patency of bronchial artery revascularization grafts was reliably identified in 7 of the 8 patients. One patient had inadequate image quality because of void artefacts caused by haemostatic clips. It is concluded that MR angiography is a reliable method for assessing the patency of bronchial artery revascularization grafts.

Bronchial artery revascularization improves tracheal anastomotic healing after lung transplantation.

The study aimed to clarify the role of direct bronchial artery revascularization (BAR) after en bloc double-lung (DLT) and heart-lung transplantation (HLT). Group I comprised eight patients with en bloc DLT or HLT and successful BAR, while group II included 14 DLT or HLT cases without BAR or with failed BAR. From these groups, 2 subgroups were extracted: group III, including 6 cases of en bloc DLT with successful BAR and group IV 10 HLT cases without or with failed BAR. Airway healing was evaluated at bronchoscopy and patency of BAR with angiography. Pulmonary viral, bacterial and fungal infections, rejections and bronchiolitis obliterans syndrome (BOS) were registered. Tracheal healing at 2 weeks and 3 months was better in group I than in group 1 (p = 0.003 and p = 0.05, respectively). Compared with group IV, tracheal anastomotic healing at 2 weeks was better in group III (p = 0.007) and tended to be better also after 3 months (p = 0.07). The incidence of infections, rejection or BOS did not differ between groups I and II. BAR thus improved healing of tracheal anastomosis.

Fatal and life-threatening complications in antireflux surgery: analysis of 5,502 operations.

BACKGROUND: There have been few comprehensive studies relating to the life-threatening or fatal complications of antireflux surgery. METHODS: Some 5502 antireflux operations were performed in Finland between January 1987 and January 1996 (population approximately 5 million); 3993 procedures (72.6 per cent) were open fundoplications, 1162 (21.1 per cent) laparoscopic fundoplications and 347 (6.3 per cent) other anti-reflux procedures. RESULTS: There were 43 fatal or life-threatening complications (prevalence 0.8 per cent). Twenty-two followed primary open fundoplication (prevalence 0.6 per cent), 15 laparoscopic fundoplication (prevalence 1.3 per cent) (P < 0.05), one refundoplication and five other antireflux procedures. The overall mortality rate was 0.3 per cent. Nine patients (0.2 per cent) died after open fundoplication, one (0.1 per cent) following laparoscopic fundoplication (P = 0.43), one following refundoplication and four after other antireflux procedures. Laparoscopic fundoplication was followed by 14 non-fatal life-threatening complications (prevalence 1.2 per cent), open fundoplication by 13 (prevalence 0.3 per cent) (P < 0.01) and other antireflux procedures by one life-threatening complication (0.3 per cent). CONCLUSION: Laparoscopic fundoplication was associated with more life-threatening complications than open fundoplication. This may compromise the advantages of the laparoscopic technique.

A method for T1 rho imaging.

The spin lattice relaxation time (T1) is dependent on the strength of the polarizing magnetic field. The relaxation at low field strengths provides information from the processes at macromolecular level. However, the decrease of the polarizing magnetic field decreases the signal-to-noise ratio that determines the resolution of magnetic resonance images. In this report we describe a method for T1 rho imaging. The method possesses the relaxation time contrast of low field strengths with signal-to-noise ratio provided by the higher polarizing field. The relaxation time T1 rho is obtained under spin lock conditions. The spin system relaxes toward thermal equilibrium along the locking field. This process is analogous to the spin lattice relaxation at low field strength and characterized by the time constant T1 rho. T1 rho and T1 rho-dispersion may provide new imaging parameters for noninvasive tissue characterization.

Intracranial hematomas studied by MR imaging at 0.17 and 0.02 T.

The contrast in magnetic resonance (MR) images relies mainly on the relaxation time differences between the tissues. The relative differences in relaxation times T1 are bigger at lower field strengths, although the absolute values of T1 are smaller. A shorter T1 is also advantageous for the contrast of the T2 and proton density weighted images because of the more complete recovery of the spin system during the repetition time TR. Scrutiny of the clinical results of MR shows some unsolved problems in the specificity of diagnosing fresh intracranial hematomas. Low field MR imaging at 0.02 T seems to offer new vistas in this sense. Fresh subdural hematoma was more easily detected and differentiated at 0.02 T than at 0.17 T. The T2 of fresh intracranial hematomas was rather short compared with cerebrospinal fluid and edema and, unlike T1, was not highly dependent on magnetic field strength. The different visualization of acute versus late intracerebral hematoma and the changes during the resorption were demonstrated in follow-up studies of two patients at 0.17 T and of one at 0.02 T. In one patient the same lesion was imaged successively at both field strengths, showing the divergent contrast in the inversion recovery images at 0.02 and 0.17 T.

Low field (0.02 T) nuclear magnetic resonance imaging of the brain.

Many technical and instrumental alternatives are available to obtain good spatial and contrast resolution in magnetic resonance (MR) imaging. Optimum field strength remains a controversial question. In spite of its inherent low signal-to-noise ratio, low field imaging exhibits some advantages. It is well established that the relaxation times are dependent on the magnetic field strength. In low fields the relaxation times, especially T1, are shorter and the relative differences of T1 between different tissues are larger. Other benefits are the ease of installation of the device, its cost effectiveness, and the obvious avoidance of hazards caused by the magnetic field. In this report we describe six cases of cerebral lesions studied with an MR imager operating at a field strength of 0.02 T (200 G). This is the lowest field strength reported in clinical MR imaging. The information obtained was equal to that of the CT studies performed on the same patients.

Cerebral MR and CT imaging in Creutzfeldt-Jakob disease.

Magnetic resonance (MR) imaging and CT of three patients with Creutzfeldt-Jakob disease (CJD) showed bilateral cortical atrophy and no apparent white matter changes. Serial examinations revealed the progressive nature of the atrophy, findings compatible with the patients' clinical deterioration. At autopsy some white matter abnormalities were detected in one patient 6 months after MR imaging. The available data suggest that the white matter abnormalities, if present, develop during the final stage of CJD.

Cerebral MR and CT imaging in polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy.

Cerebral magnetic resonance (MR) and CT imaging of two patients with polycystic lipomembranous osteodysplasia with sclerosing (PLO-SL) showed widespread progressive central and cortical atrophy. Computed tomography revealed calcifications in the area of the caudate nuclei and putamina in both patients. A reduced volume of brain white matter with deep cortical sulci was the most striking MR finding. Rather short relaxation times in periventricular areas adjacent to ventricular bodies were also observed.

A method for chemical shift imaging: demonstration of bone marrow involvement with proton chemical shift imaging.

A new method for chemical shift imaging is described. In this method the spin-echo signals are collected with the field gradient switched on, which reduces the imaging time considerably. A human bone marrow pathology is demonstrated by proton chemical shift imaging.

Cerebral NMR and CT imaging in dementia.

Thirteen patients with different types of dementia were studied with nuclear magnetic resonance (NMR) and CT imaging of the brain. The overall correlation between CT and NMR findings was good. Areas of hypodensity in cerebral white matter on CT were especially well visualized in the T2-weighted NMR images. Hypodense areas were seen in the white matter of patients with vascular dementias but not in those with primary degenerative dementias. Thus, the presence or absence of white matter changes may be an important factor in the differential diagnosis of vascular dementia and primary degenerative dementia. On the basis of NMR and CT findings, it was difficult to distinguish between the lacunar state type and Binswanger type of vascular dementia. It is suggested, therefore, that these two subgroups of vascular dementia be commonly named angiopathic dementia.

Visualization of brain infarction with nuclear magnetic resonance imaging.

Nine patients with cerebral or cerebellar hemispheric infarction and two patients with brain stem lesions were studied with NMR imaging in order to examine the lesion with different weightings on the various NMR parameters. The time interval between examination and the acute onset of the stroke varied from one day to six months. The lesions were clearly detected by the T1 weighted inversion recovery sequence but the tissue contrast was better using the spin echo sequence with a long repetition rate and a long echo delay (SE2000/100). In two patients the brain stem lesions were invisible with CT, but were easily depicted with NMR. In one of them the further progress of the lesion was also confirmed and visualized with the follow-up NMR study.

Chronic subdural hematoma: demonstration by magnetic resonance.

The ability of magnetic resonance (MR) to identify intracranial hematomas was tested in five patients with clinical and computed tomographic signs of chronic subdural hematoma. The extracerebral collections were displayed as a zone of bright intensity using the T1-weighted inversion recovery (IR 1,500/400) sequence, reflecting the lesions' short T1 relaxation times. The collections also showed high intensity using the spin echo (SE) sequence, with a longer delay of 100 ms and 160 ms, reflecting the long T2 relaxation time. The spin echo sequence with a repetition time of 500 ms and an echo delay of 160 ms (SE 500/160) almost effaced other structures in the image, thus increasing the specificity of this pulse scheme for detection of chronic blood collections. Although in two of the five patients the subdural hematomas were in the isodense CT phase, all were easily visualized with MR.

Nuclear magnetic resonance (NMR) imaging of intracerebral hemorrhage in the acute and resolving phases.

Nuclear magnetic resonance imaging of intracerebral hemorrhage revealed a considerable difference in the appearance of the bleedings in the acute and resolving phases. Attention is drawn to the shortening of the relaxation time T1 within the first 2 weeks after the acute onset of symptoms with the location of the change at the periphery of the lesion. The change was most evident with T1 dependent inversion recovery sequence (IR 1,500/400). With this pulse scheme the acute hemorrhage was visualized as a dark area during its early days. A bright zone, reflecting the shorter T1, was not seen until the resolving phase at the end of the 1st week. Although its pathophysiological aspects are so far unknown, this finding may offer an opportunity for dating intracerebral hemorrhages.

Serial nuclear magnetic resonance (NMR) imaging in patients with cerebral infarction.

Seven patients with supratentorial infarction were studied by means of serial nuclear magnetic resonance imaging using saturation recovery (SR) and proton density (PD) sequences. The earliest changes were visible in the more sensitive T1 dependent images (SR) and may reflect the cytotoxic component of ischemic brain edema. Further progress was also clearly discernible in the PD images and may mainly reflect the slower vasogenic component of ischemic brain edema. Nuclear magnetic resonance imaging seems to provide a new approach to early diagnosis of ischemic brain infarction. Furthermore, it may elucidate some aspects of the pathophysiology of ischemic stroke in man.