Ingolf P. Arlart

Magnetic Resonance Angiography of the Abdominal Aorta

Magnetic resonance angiography (MRA) of the abdominal aorta was performed in 36 patients using the “bright-blood” technique on the basis of a series of flow-compensated breath-hold 2 D-GE pulse sequences. Diverse diseases included complete occlusion, stenosis, atherosclerotic or dissecting aneurysm and renal artery stenosis. Coronal and axial projection angiograms [maximum intensity projection (MIP) algorithm] and individual GE images were compared with DSA and contrast-enhanced computed tomography (CT). Our data showed a good correlation of MR and digital subtraction arteriography (DSA) or CT resp. in all cases, when both rotating MIP angiograms and individual GE images were analyzed. Thus, MR is suggested to be a useful noninvasive diagnostic method for the abdominal aorta, particularly in preoperative staging of aneurysms, aortic occlusive disease, and stenosis of the proximal main renal artery. Drawbacks of the method are a signal loss in slow or turbulent flow conditions, and unsatisfactory spatial resolution in small vessels.

Predictive value of radionuclide methods in the diagnosis of unilateral renovascular hypertension

The validity of noninvasive (iodine-131 iodohippurate renogram, iodine-131 ortho-iodohippurate clearance, indium-113m EDTA-technetium-99m DTPA sequential renal scan) and invasive (xenon-133 washout) radionuclide screening tests was evaluated in the diagnosis of 105 patients with unilateral renovascular hypertension (RVH) and in 45 patients with essential hypertension (EH). In RVH positive findings on the stenosed side were noted in 73% of renograms, 73% of o-iodohippurate-clearance tests (n=22), 81% of sequential renal scans, and 90% of xenon-washout studies (n=67). In a subgroup of 55 retrospectively selected patients with normal or improved blood pressure following renovascular surgery, the preoperative findings had been positive on the stenosed side in 78% of renograms, 75% of o-iodohippurate-clearance tests (n=20), 85% of sequential renal scans, and 93% of xenon-washout studies (n=23). The sequential renal scan appears to be a sufficiently reliable method in noninvasive screening for unilateral RVH, although invasive xenon-washout studies show a higher percentage of hemodynamic alterations in the stenosed kidney. O-iodohippurate clearance tests, and in particular xenon-washout studies, can reveal arteriosclerotic lesions in the contralateral, non-stenosed kidney, which may be of importance when the decision for renovascular surgery is pending.

Laser-assisted balloon angioplasty in complete femoropopliteal occlusions: Preliminary results

Laser-assisted balloon angioplasty (LA) using a Nd-YAG laser with a sapphire tip probe was performed in 40 selected patients with complete chronic femoropopliteal occlusions (SFA n=30, PA n=10), in whom the lesion was resistent to conventional guidewire/catheter traversal. Overall technical success rate was 77.5% (31/40). Technical failure occurred in nine cases due to calcifications (n=2), imminent perforation (n=5), or complete perforation (n=4). In I case a Simpson atherectomy was done following LA. In addition, 3 cases of peripheral embolizations were managed successfully by selective fibrinolysis and thrombus aspiration. Follow-up studies up to 14 months demonstrated a clinical improvement in 87% (27/31). Early reocclusion rate was 4/31; after 2–14 months, reocclusion rate was 7/31. Our results demonstrate that LA may be recommended for chronic occlusions resistent to conventional guidewire or catheter traversal in spite of a relatively high rate of technical failure and complications, and recurrence.

Peripheral renal vascular disease in essential hypertension: hemodynamic, angiographic, and endocrine assessment

Renal hemodynamic (133Xe-washout) and angiographic studies were performed in 46 patients with essential hypertension to demonstrate a possible correlation between graded renal small vessel disease and changes in renal blood flow. In addition, influence of the effects of duration of hypertension, diastolic blood pressure values and renal vein renin activity on hemodynamic and arteriographic findings were evaluated. Our results demonstrate that in patients with accelerated or severe renal small vessel disease the mean and cortical renal blood flow is significantly reduced (P<0.001). Furthermore, renal arteriosclerosis becomes evident in patients with long-standing hypertension, high diastolic blood pressure values, and elevated renal vein renin levels. Correlations between renal blood flow and renal vein renin activity (r=0.45) apparently are governed by severity of the renal arteriosclerosis.

Intravenous digital subtraction angiography in patients with femoral arteriovenous fistulas and ilio-iliac crossover graft

Fourteen patients with femoral arteriovenous (AV) fistulas and ilio-iliac crossover bypass grafts after postthrombotic occlusion of an iliac vein were studied by intravenous digital subtraction angiography (IV DSA). Digital radiographys utility may be evaluated in the demonstration of the vascular status of AV fistulas and venous return through the reopened iliac vein or ilio-iliac graft. Digital subtraction imaging is a suitable modality to plan operations, such as closure of temporary AV fistula. In follow-up studies of these cases, patency of the crossover bypass can be assessed by noninvasive DSA of the ascending veins.

Abdominal Aorta and Its Branches

The abdominal aorta is responsible for transporting blood into the arteries of the intra- and retro-peritoneal parenchymal organs as well as into the pelvis and lower extremities. The main branches of the abdominal aorta are the splanchnic and renal arteries. Splanchnic vessels supply the liver, spleen, pancreas, duodenum, and the stomach via the celiac artery, and the intestinal tract via the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA). Through the renal arteries approximately 20% of the cardiac output volume is transported into the kidneys.

Digital Subtraction Angiography (DSA) in Renal and Renovascular Hypertension: Diagnostic Value and Application in Follow-Up Studies after PTA

Diagnosis of renovascular hypertension is of particular interest because it is curable by vascular surgery or percutaneous transluminal angioplasty (PTA). Transvenous digital subtraction angiography (DSA) is a minimally invasive method of importance in detecting renal hypertension of different origins (pre-, intra-, postrenal). This study was carried out to assess the value of transvenous DSA in analyzing the renal arteries and renal parenchyma, in detecting renal artery stenosis, and in controlling PTA results. Our results demonstrate that image quality of transvenous DSA of the renal arteries was excellent (diagnostic in 474 of 510 cases, 93%). A large number (62%) could be analyzed following one injection of contrast medium, in 25% a second, and 6% a third injection was necessary. In follow-up studies after PTA (1 week to 24 months) patients with normalized blood pressure values (16/33) had a completely reopened arterial segment and normal parenchyma of both kidneys. In persistent or recurrent hypertension (17/33) restenosis could be detected by transvenous DSA in 2 cases and renal parenchymal lesions in 8 cases. Reversible intimal dissections observed immediately following PTA had no influence on blood pressure results. Intra-arterial DSA is recommended when renal artery stenosis is to be evaluated for PTA and when the result of balloon catheter dilatation is to be evaluated. Intra-arterial DSA is indicated to exclude stenosis following kidney transplantation and to determine perfusion of the graft (parenchyma and venous return) taking advantage of small volumes and concentrations of contrast material made possible by digital contrast enhancement.

Large Veins of the Body and Extremities

The large veins of the extremities, the abdominal parenchymal organs, the retroperitoneum, and the mediastinum are responsible for the transport of deoxygenated blood back to the right atrium and the pulmonary arteries for it to become oxygenated again during the lung passage. Compared with the arteries of the body, the venous system shows a larger number of anatomic variants in vascular course and caliber. Venous blood flow and pressure conditions are completely different from those of arteries, leading to different specific pathologies. One of the main venous disorders is acute thrombosis most frequently located in the deep lower extremity and pelvic veins, which may be a serious and life-threatening complication when pulmonary embolism occurs. Thrombotic disease of the upper extremity and central mediastinal veins in the majority of cases is caused by temporary vein catheters or access devices. Occlusion of the vena cava is mostly due to extravascular tumor compression.

Der Nutzen der digitalen Subtraktionsangiographie zur Lokalisation einer fehlmündenden Lungenvene bei einem angeborenen Shuntvitium

SummaryThe exact analysis of an anomalous pulmonary venous return in patients with congenital shunt disease can lead to some difficulties when using the standard cateterization techniques. A left-sided anomalous pulmonary vein was suspected in a case with atrial and ventricular septal defects, but could not be evaluated during the catheterization procedure. The pathological vessel could be demonstrated exactly only by venous digital subtraction angiography. Thus, the digital subtraction angiography showed a diagnostic benefit in this complex shunt disease and should be considered in further problematic cases.The exact analysis of an anomalous pulmonary venous return in patients with congenital shunt disease can lead to some difficulties when using the standard catheterization techniques. A left-sided anomalous pulmonary vein was suspected in a case with atrial and ventricular septal defects, but could not be evaluated during the catheterization procedure. The pathological vessel could be demonstrated exactly only by venous digital subtraction angiography. Thus, the digital subtraction angiography showed a diagnostic benefit in this complex shunt disease and should be considered in further problematic cases.

Einfluß von Saralasin auf Plasma Renin Aktivität und Arginin-Vasopressin bei Patienten mit angiotensinabhängiger Hypertonie

A central stimulatory effect of angiotensin II (AII) on the secretion of arginine-vasopressin (AVP) has been described. The competitive blocker of AII, saralasin (SAR) has been used for diagnostic purposes in angiotensin-dependent hypertension. In addition SAR has a partially agnoistic effect. The aim of the present study was to demonstrate whether AVP-levels can be influenced during SAR-induced renin stimulation. In 9 patients with essential hypertension blood pressure dropped significantly under SAR (10 microgram/kg/min over a 30 min period). Before and after SAR plasma renin activity (PRA) and AVP were measured by RIA, SAR evoked significantly increments of PRA in all patients and of AVP in 6 patients. The increased serum concentrations of AVP following SAR may be explained either by the depressor effect of SAR, its diminished concentration at the central receptor, or a partial AII-agonistic effect.SummaryA central stimulatory effect of angiotensin II (AII) on the secretion of arginine-vasopressin (AVP) has been described. The competitive blocker of AII, saralasin (SAR) has been used for diagnostic purposes in angiotensin-dependent hypertension. In addition SAR has a partially agonistic effect. The aim of the present study was to demonstrate whether AVP-levels can be influenced during SAR-induced renin stimulation. In 9 patients with essential hypertension blood pressure dropped significantly under SAR (10 µg/kg/min over a 30 min period). Before and after SAR plasma renin activity (PRA) and AVP were measured by RIA. SAR evoked significant increments of PRA in all patients and of AVP in 6 patients. The increased serum concentrations of AVP following SAR may be explained either by the depressor effect of SAR, its diminished concentration at the central receptor, or a partial AII-agonistic effect.ZusammenfassungEine zentral stimulierende Wirkung von Angiotensin II (AII) auf die Sekretion von Arginin-Vasopressin (AVP) ist beschrieben worden. Als kompetitiver Blocker von AII fand das Analogon Saralasin (SAR) zum Nachweis einer angiotensinabhängigen Hypertonie Verwendung. Zusätzlich wurde eine partiell agonistische Wirkung von SAR nachgewiesen. Ziel der vorliegenden Studie war es festzustellen, ob die durch SAR induzierte Reninstimulation zu meßbaren AVP-Veränderungen führt. Bei 9 essentiellen Hypertonikern, deren arterieller Blutdruck während einer SAR-Infusion (10 µg/kg/min über 30 min Dauer) signifikant abfiel, wurden vor Beginn und am Ende der Applikation Plasma Renin Aktivität (PRA) und AVP radioimmunologisch bestimmt. Bei allen Patienten führte das depressorisch wirkende SAR zu einem signifikanten Anstieg der PRA, bei 6 Patienten zu einer signifikanten Erhöhung von AVP im Serum. Die unter SAR festgestellten AVP-Anstiege erklären sich möglicherweise durch die periphere depressorische Wirkung, durch eine mangelnde Konzentration am zentralen Rezeptor oder durch eine partielle AII-agonistische zentrale Wirkung.