F. Grabenwöger

Intrarenal Doppler ultrasonography: which vessel should be investigated?

The aim of our study was to determine whether the site of intrarenal Doppler measurement influences diagnosis of renal artery stenosis. In an experimental test, three sheep with variable degrees of renal artery stenosis were investigated. In each animal, the resistive index from renal segmental arteries correlated better with mean pressure gradient (r = 0.85, 0.71, 0.85) and had lower standard deviation (s = 0.02 to 0.05) than resistive index from interlobar arteries (r = 0.48, 0.54, 0.61) (s = 0.03 to 0.11). In two animals the difference was significant (correlation: P < or = 0.01, P = 0.13, P < or = 0.05; standard deviation: P < or = 0.01, P < or = 0.34, P < or = 0.05). For detecting renal artery stenosis, vessels within the renal sinus should be used for Doppler sampling.

Mesh tube-calibrated varicose veins for coronary artery bypass grafting

Complex arterial bypass grafting may be contraindicated for patients with multivessel disease and inadequate saphenous veins. In such cases varicose veins may be used as bypass conduits after calibration by insertion into mesh tubes. After in vitro and experimental testing, as well as gratifying results in infrainguinal arterial reconstructions, wrapped varicose vein grafts in addition to arterial bypass grafts were used in 6 patients undergoing coronary artery bypass grafting.

Six-year follow-up after heart valve replacement with the Edwards Duromedics bileaflet prosthesis.

The Duromedics Edwards valve (DE) was designed with a self-irrigating hinge mechanism to reduce the rate of thromboembolic complications. This report presents a prospective follow-up of patients after valve replacement with this prosthesis in a university hospital. Five hundred seven patients had DE prostheses implanted in the aortic (n = 268), mitral (n = 183) or aortic and mitral positions (n = 56). The perioperative mortality was 6.9%. Follow-up was 98% complete, comprising 2009 patient years for a mean follow-up of 48 months: (range 27-84). The actuarial freedom from complications is calculated as follows (linearized rates in parentheses): late mortality 81.0 +/- 2.3% (3.4%/patient year), thromboembolism 93.5 +/- 1.5% (1.1%/patient year), anticoagulation-related hemorrhage 89.5 +/- 2.0% (1.9%/patient year), prosthetic valve endocarditis 96.0 +/- 1.2% (0.7%/patient year), valve-related mortality 93 +/- 1.8% (1.5%/patient year), valve failure 89 +/- 2.0% (2%/patient year), treatment failure 88.0 +/- 2.0% (2.2%/patient year) and all valve-related morbidity and mortality 74.0 +/- 2.8% (5.3%/patient year). Two events of leaflet escape were observed in the study group (0.09%/patient year). Both patients were reoperated successfully. Mechanical hemolysis was subclinical in all cases. The DE shows a complication rate comparable to other modern mechanical valve prostheses. After solving the problem of durability, reconsideration of this valve is worthwhile due to its low risk of thromboembolic complications.

Improved spontaneous endothelialization by postfixation treatment of bovine pericardium.

The longstanding release of locally cytotoxic glutaraldehyde concentrations from fixed biological materials is one reason for the lack of spontaneous endothelialization in vivo and in vitro of biological grafts (and valves). Preliminary studies have shown that bovine pericardium postfixation-treated with aminoacids may be endothelialized in vitro. To test whether such treatment improves spontaneous endothelialization in vivo 8 cm long segments grafts (6 mm I.D.) were interposed into the carotid arteries of 10 sheep. Ten grafts were sewn from postfixation treated pericardium (PTP), 4 from standard glutaraldehyde fixed pericardium (GAP) and 6 polytetrafluoroethylane (PTFE) grafts were implanted to study the degree of spontaneous endothelialization. In two pregnant animals, all grafts occluded (2 PTP, 1 GAP, 1 PTFE). In the remaining animals 1 additional PTFE graft occluded and 2 PTFE and 1 GA grafts showed significant thrombotic obstruction. The patent grafts were harvested at 3 months and the surface covered with red thrombus was determined by planimetry. PTP grafts had significantly less (12.2% +/- 15%) thrombotic appositions than glutaraldehyde treated grafts (49% +/- 20%; P = 0.01) and PTFE grafts (40.5% +/- 13%; P = 0.01). In the central areas of the PTP grafts, endothelial cells spread directly on the collagenous matrix and produced a basal lamina. In GAP, endothelial cells spread on amorphous material or macrophages and in PTFE grafts, only a neointima composed of myofibroblasts was endothelialized. Neutralization of glutaraldehyde concentrations by postfixation with aminoacids improves spontaneous endothelialization in vivo in biological materials.

Intraoperative and early postoperative colour Doppler sonography after carotid artery reconstruction: follow-up of technical defects

Abstract We studied 50 patients with intraoperative colour-coded Doppler sonography (CCDS) after carotid artery reconstruction. Technical defects could be detected in 19 cases (38 %): residual plaques in 9, flaps in 8 and strictures in 2. In 9 cases (18 %) the carotid endarterectomy was revised. One residual plaque and one residual stricture caused thrombosis at the operative site a few hours postoperatively. One of the patients with residual plaques developed a high-grade stenosis within the follow-up period. Of the patients with residual plaques two had a medium-grade stenosis at follow-up. Six flaps decreased in size or disappeared within 1 week after operation. No patient with a flap developed a stenosis within the follow-up period. Our findings seem to indicate that correction of intimal flaps less than 10 mm in size is not necessary.

Mesh-Constricted Varicose and Dilated Veins Used as Arterial Bypass Grafts

To avoid non-autogenous vascular prostheses in coronary and peripheral vascular procedures, otherwise unusable dilated, varicose or thin-walled veins can be implanted as naturally endothelialized grafts after being calibrated by insertion into mesh tubes. In six sheep the 14 mm diameter jugular vein was inserted into a 12 cm long, 6 mm diameter Dacron mesh tube and implanted as a femoropopliteal graft. On the contralateral side the femoral vein with a maximal diameter of 7 to 8 mm was implanted. At control angiography after two months all grafts were patent, none of the wrapped grafts showed wrinkles or signs of anastomotic hyperplasia. Segments of wrapped veins were casted in paraffin under physiological pressure and cut transversely. In all cases the vein wall was pressed against the mesh tubes without forming folds. Mesh-wrapped varicose veins were used for three femorocrural and seven femoropopliteal reconstructions. All grafts showed a smooth flow surface at control angiography. Identations occurred only at sites where thick-walled side branches had been ligated rather than oversewn. One popliteo-pedal reconstruction occluded after two months and one patient with a crural reconstruction died two months after surgery with a patent graft. The remaining grafts were patent after 11 (2-32) months. Oversized veins can be considerably constricted by tubes without forming wrinkles. By this technique varicose veins can be used as bypass grafts and in general vein grafts can be matched in size to the recipient vessel.

Coefficient of variation : A powerful doppler ultrasonographic parameter for detection of renal artery stenosis

The aim of our study was to objectively compare the effectiveness of various Doppler parameters in the diagnosis of renal artery stenosis. In three sheep, variable degrees of renal artery stenosis were induced and renal segmental arteries were investigated using pulsed Doppler sonography. In each animal the standard deviation of the instantaneous peak velocity within one cardiac cycle normalized by the mean peak velocity (coefficient of variation) had significantly higher normalized regression coefficients (k* = ‐0.215, average of three animals) when compared to resistive index (k* = ‐0.090) and acceleration index (k* = ‐0.069). In each individual animal, coefficient of variation detected lower pressure gradients (6.3 mm Hg, average value) than did resistive index (13.4 mm Hg) or acceleration index (17.3 mm Hg). The coefficient of variation may detect the presence of pressure gradients in renal artery stenosis more accurately than acceleration index or resistive index.

Radiologic search for embolized leaflets of prosthetic heart valves: A report of two cases

In a radiologic search for embolized leaflets of Edwards-Duromedics bileaflet valves in 2 patients, the embolized fragments were localized in the iliac vessels using computed tomography. Sonography was successful in one case and standard X-ray films of the abdomen were negative in both cases.In vitro investigations with Björk-Shiley and Edwards-Duromedics leaflets suggested that standard X-ray films of the abdomen and pelvis should be considered as the first investigational technique. If negative, computed tomography of the lower abdomen should be done.

An unusual cause of haemobilia.

Haemobilia, a communication between blood vessels and the biliary tract, is usually secondary to trauma, vascular disease, inflammatory disorders, gallstones or tumours (Hirsch et al, 1982). An extremely rare cause is presented, namely tuberculosis, presumably related to erosion of the hepatic artery and formation of a pseudoaneurysm. A 16-year-old girl was admitted with haematemesis and melaena. The patient had been well until the age of 14 years, when she experienced symptoms of fever, night sweats and fatigue and was diagnosed as having pneumonia.

An unusual visualization of the gallbladder by somatostatin receptor (SSTR) scintigraphy: usefulness of hepatobiliary imaging for differential diagnosis.

An unusual visualization of the gallbladder by somatostatin receptor (SSTR) scintigraphy: usefulness of hepatobiliary imaging for differential diagnosis