[Diffusion weighted MRI: ischemic and traumatic injuries of the central nervous system]. / Diffusionsgewichtete MRI: Ischämische und traumatische Verletzungen des Zentralnervensystems.

Diffusion weighted magnetic resonance imaging (DWI) represents a recent development that extends imaging from the depiction of the neuroanatomy into the field of functional and physiologic processes. DWI measures a fundamentally different physiologic parameter than conventional MRI. Image contrast is related to differences in the microscopic motion (diffusion) of water molecules within brain tissue rather than a change in total tissue water. Consequently, DWI can reveal pathology where conventional T1- and T2-weighted MR images are negative. DWI has clinically proven its value in the assessment of acute cerebral stroke and trauma by showing cerebral injury early due to ist ability to discriminate between lesions with cytotoxic edema (decreased diffusion) from lesions with vasogenic edema (increased diffusion). Full tensor DWI allows to calculate a variety of functional maps, the most widely used maps include maps of apparent diffusion coefficients and isotropic diffusion. In addition maps of anisotropic diffusion can be calculated which are believed to give information about the integrity and location of fiber tracts. This functional-anatomical information will most probably play an increasingly important role in the early detection of primary and secondary tissue injury from various reasons and could guide and validate current and future neuroprotective treatments.

[Acute mesenteric ischemia: value of computerized tomography diagnosis]. / Akute mesenteriale Ischämie: Stellenwert der computertomographischen Diagnostik.

Acute mesenteric ischemia (AMI) is an acute life-threatening vascular emergency. Clinical presentation is often unspecific. Rapid diagnosis and therapy are essential in survival. Contrast-enhanced spiral computed tomography is sensitive and highly specific in the diagnosis of AMI.

Annuloplasty and aortoplasty as modifications of the Ross procedure for the correction of geometric mismatch.

BACKGROUND AND AIM OF THE STUDY: Pulmonary autograft replacement of the aortic valve (the Ross procedure) is reliable and durable; however, geometric mismatch of the autograft and systemic outflow tract may lead to poor results. Manipulation of the aortic annulus and sinotubular diameters to match the autograft can prevent geometric mismatch, and improve results. METHODS: Annuloplasty and/or aortoplasty were combined with the Ross procedure in 26 of 44 patients (median age 42.5 years; range: 3 days to 62 years) undergoing surgery between April 1994 and July 1998. Plication of the aortic annulus at either two or three of the commissures was done in five cases, aortic annulus fixation with an external pericardial pledget incorporated in the proximal suture line in 12 cases, and tailoring aortoplasty in nine patients. RESULTS: There was one operative death. Two patients required reoperation; one for progressive autograft dysfunction and one for homograft dysfunction. Annular fixation was performed on the patient requiring reoperation for autograft dysfunction. Doppler echocardiography during the follow up (median 9 months; range: 1-50 months) revealed 10 patients with trace 1+ and one patient with 2+ aortic insufficiency. Trace 1+ and 2+ aortic stenosis were present in one patient each. None of the patients undergoing commissural plication had significant regurgitation or stenosis. Both patients with stenosis underwent annular fixation. Aortoplasty was associated with 1+ insufficiency in two patients. CONCLUSION: Prevention of geometric mismatch between the autograft and systemic outflow tract at the annulus and sinotubular junction by plication techniques allows better performance of the autograft, and extends the Ross procedure to patients who otherwise may be unable to undergo such surgery. Fixation may provide similar benefit, but appears to be more susceptible to insufficiency and stenosis.

[Crohn's disease: evaluation with computed tomography and magnetic resonance imaging]. / Morbus Crohn: Abklärung mittels Computertomographie und Magnetresonanztomographie.

Computed Tomography should increasingly be used as a minimally invasive alternative to small bowel enteroclysis. Firstly, CT-examination is less stressful to the patients. Secondly, information is not only provided about the bowel lumen but in addition the thickness and architecture of the small bowel wall as well as the adjacent structures can be evaluated. Extraintestinal lesions/complications are easily diagnosed. Moreover, CT can be used as primary screening method in the evaluation of abdominal complaints of unknown origin. Next to Crohn's disease, numerous other small bowel diseases can be excluded. Magnetic resonance imaging will become another alternative imaging technique in future. Major advantages are the lack of ionizing radiation, the multiplanar scanning technique and the possibility of extensive postprocessing by virtual endoscopy.

Efficacy and cost-effectiveness of preoperative IABP in patients with ejection fraction of 0.25 or less.

BACKGROUND: The purposes of this study are to determine whether patients with severe left ventricular dysfunction benefit from prophylactic insertion of an intraaortic balloon pump and to evaluate its cost-effectiveness. METHODS: Between January 1991 and December 1995, 163 consecutive patients with a left ventricular ejection fraction of 0.25 or less underwent isolated coronary artery bypass grafting. An intraaortic balloon pump was inserted before operation in 37 patients (group A). The remaining 126 patients underwent operation without preoperative insertion of the device (group B). Preoperatively, 91.9% (34/37) of group A patients and 54.8% (69/126) of group B patients were in New York Heart Association functional class III or IV (p < 0.001). RESULTS: The 30-day mortality rate was 2.7% (1/37) and 11.9% (15/126) for groups A and B, respectively (p < 0.005). All deaths occurred in patients in functional class III or IV. In group B, 28 patients (22.2%) required an intraaortic balloon pump after cardiotomy for low cardiac output, 42.9% (12/28) of whom died. Median postoperative hospital stay was 9.9 days and 12.0 days, and mean hospital charges were $50,627 and $54,818 for survivors in groups A and B; respectively (p = not significant). CONCLUSIONS: Our experience suggests that patients with severe left ventricular dysfunction undergoing coronary artery bypass grafting may benefit from preoperative intraaortic balloon pump insertion, especially patients in functional class III or IV. This approach improved survival significantly, reduced hospital stay, and was more cost-effective.

Which is the graft of choice for the right coronary and posterior descending arteries? Comparison of the right internal mammary artery and the right gastroepiploic artery.

BACKGROUND: The graft of choice for the left anterior descending coronary artery is the left internal mammary artery because of superior long-term patency. However, controversy exists regarding the graft of choice for the right coronary artery and for the posterior descending branch. METHODS AND RESULTS: Two types of pedicled arterial grafts were used for the right coronary and the posterior descending arteries in patients undergoing coronary bypass surgery between January 1991 and September 1994. Group A comprised 114 patients with a right internal mammary artery (RIMA) graft, and group B consisted of 127 patients with an in situ right gastroepiploic artery (R-GEA) graft. Mean age was 56.9 years in group A and 63.3 years in group B; 7.9% (9 of 114) and 33.9% (43 of 127) were diabetics in groups A and B, respectively. Overall mortality was 2.6% (3 deaths) for group A and 3.9% (5 deaths) for group B (P = NS). However, the prevalence of perioperative myocardial infarction in the right coronary artery distribution was significantly higher for group A (5.3%, or 6 of 114) than for group B (0.8%, or 1 of 127; P < .05), and the reoperation rate for graft failure (from 0 to 12 months after surgery) was significantly higher for the RIMA (4.4%, or 5 of 114) than for the R-GEA (0%; P < .05). Also, the prevalence of deep sternal wound infection in diabetics was significantly higher in group A (22.2%, or 2 of 9) than in group B (4.6%, or 2 of 43; P < .05). CONCLUSIONS: Our preliminary results suggest that the failure rate of the RIMA graft is significantly higher, especially if used as a pedicled graft to the posterior descending artery. The risk of sternal wound complications is greater in diabetics if both internal mammary arteries are used for grafting. Therefore, the R-GEA graft is preferred in diabetics and whenever the posterior descending artery is the target vessel.

Radial artery graft for coronary revascularization: technical considerations.

BACKGROUND: Use of the radial artery for coronary artery bypass grafting is controversial. METHODS: Between November 1992 and December 1994, the radial artery artery graft was used in 165 patients (mean age, 63.7 years) undergoing coronary revascularization. To prevent spasm, the radial artery was not skeletonized, and calcium-channel blockers were administered routinely. RESULTS: No ischemic or functional complications occurred in the hand after harvesting of the radial artery. Only 1 patient (0.6%) sustained a perioperative myocardial infarction in an area revascularized with a radial artery. The overall mortality was 3.0% (5 patients), but no deaths were caused by failure of the radial artery graft. During a mean follow-up of 14.0 months, angina recurred in 5 patients (3.0%), all of whom had widely patent radial artery grafts on angiography. Radionuclide exercise studies were performed 1 year after operation in 84 patients, 2 of whom (2.4%) had stress-induced defects in areas grafted with a radial artery. CONCLUSIONS: Perioperative myocardial infarction, mortality, and recurrent angina usually were not related to failure of the radial artery graft. Our results suggest that the radial artery is an excellent alternative conduit for myocardial revascularization and may be used safely, especially in patients with poor-quality or unavailable saphenous veins.

An algorithm for the surgical management of chronic abdominal aortic occlusion and occluded aortofemoral grafts.

An algorithm for the surgical management of chronic abdominal aortic occlusion is presented based upon experience of treating 60 consecutive patients. Of 33 patients with juxtarenal aortic occlusion, 17 underwent aortofemoral bypass (AFB), 10 descending thoracic aortofemoral (DTAF), 5 axillofemoral (AxF) bypass, and 1 ascending thoracic aortofemoral bypass. Of 11 patients with mid or distal aortic occlusion, 8 underwent AFB, 2 DTAF and 1 AxF. Of 16 patients with aortic graft occlusion, 1 underwent AFB, 10 DTAF and 5 AxF. Acceptable risk patients were selected for AFB (26). DTAF (22) was frequently preferred for patients with occluded aortic grafts or other hazardous intraabdominal pathology. AxF (11) was used for patients with severe cardiopulmonary risk, limited life expectancy from malignancy, or when emergency procedures were required for salvage of severely ischemic limbs in debilitated patients with chronic aortic occlusion. In the AFB, DTAF and AxF groups the perioperative mortality was 8%, 5% and 36% respectively, the late mortality was 15%, 36% and 45%, and the 5-year primary cumulative graft patency was 92%, 89% and 15%.

Long term follow-up of descending thoracic aorto-iliac/femoral bypass.

A prospective study of 26 patients undergoing descending thoracic aorto-iliac/femoral (DTAI/F) bypass was conducted over a 13-year period with an average follow up of 53 months. Reasons for selecting the procedure were occluded aortic bifurcation grafts (9 patients), hostile abdomen (6), infected aortic graft (1), microaorta (10, and surgeons preference in 8 patients who had juxtarenal aortic occlusion. The operative mortality was 3.8% (1 patient). A late mortality of 36% was due to myocardial infarction (1), lung carcinoma (2), renal failure (4), stroke (1) and pulmonary insufficiency (1). Graft failure occurred in 4 patients at 23, 26, 54 and 109 months respectively. Primary cumulative patency was 86% statistically valid at 42 months. DTAI/F bypass is recommended in selected patients when conventional approaches to the aorta are considered unduly hazardous.

Descending thoracic aortobifemoral bypass for occluded abdominal aorta: retroperitoneal route without an abdominal incision.

Severe juxtarenal aortic disease and occluded aortic bifurcation grafts have prompted surgeons to seek alternative routes when reoperating. We have modified the descending thoracic aortobifemoral bypass procedure by drawing the graft through a retroperitoneal tunnel to the left groin, thereby eliminating the need for an abdominal incision. The lower thoracic area is exposed through a left anterolateral thoracotomy incision and each common femoral artery is exposed by vertical incisions in the groins. The right limb is drawn through a retrorectus tunnel to the right groin for the final anastomosis. Experience with this technique in 12 patients has demonstrated less risk of atheroemboli, less blood loss, shorter operating time, and a more rapid postoperative recovery, than is the case in reentering the abdomen for a secondary aortic procedure.