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J W Ludwig

Publications and source records attributed to J W Ludwig.

At least 19 recordsLinked to original sources
PubMed1997

Quantitative assessment of the presence of a single leg separation in Björk-Shiley convexoconcave prosthetic heart valves.

RATIONALE AND OBJECTIVES: The authors developed an analytic software package for the objective and reproducible assessment of a single leg separation (SLS) in the outlet strut of Björk-Shiley convexoconcave (BSCC) prosthetic heart valves. METHODS: The radiographic cinefilm recordings of 18 phantom valves (12 intact and 6 SLS) and of 43 patient valves were acquired. After digitization of regions of interest in a cineframe, several processing steps were carried out to obtain a one-dimensional corrected and averaged density profile along the central axis of each strut leg. To characterize the degree of possible separation, two quantitative measures were introduced: the normalized pit depth (NPD) and the depth-sigma ratio (DSR). The group of 43 patient studies was divided into a learning set (25 patients) and a test set (18 patients). RESULTS: All phantom valves with an SLS were detected (sensitivity, 100%) at a specificity of 100%. The threshold values for the NPD and the DSR to decide whether a fracture was present or not were 3.6 and 2.5, respectively. On the basis of the visual interpretations of the 25 patient studies (learning set) by an expert panel, it was concluded that none of the patients had an SLS. To achieve a 100% specificity by quantitative analysis, the threshold values for the NPD and the DSR were set at 5.8 and 2.5, respectively, for the patient data. Based on these threshold values, the analysis of patient data from the test set resulted in one false-negative detection and three false-positive detections. CONCLUSIONS: An analytic software package for the detection of an SLS was developed. Phantom data showed excellent sensitivity (100%) and specificity (100%). Further research and software development is needed to increase the sensitivity and specificity for patient data.

Adult↗
PubMed1989

Clinically unsuspected complications of arterial surgery shown by post-operative digital subtraction angiography.

Intravenous digital subtraction angiography was performed within 20 days of 678 vascular reconstructions as a routine post-operative evaluation. After 339 carotid endarterectomies, 34 patients showed a stenosis of greater than 30% and six occlusions were seen. In 157 patients after aortic aneurysm repair, we found five anastomotic aneurysms and seven stenoses of greater than 30%. After aortic bypass surgery, 77 patients were evaluated and nine stenoses were found; no anastomotic aneurysms were seen. In 105 patients with femoro-distal bypass procedures, occlusion was reported in 11 cases and stenosis in 13 cases. One patient had two anastomotic aneurysms. To summarize, major abnormalities were present in 81 cases (12.7%) and consisted of 59 stenoses of greater than 30%, 17 occlusions and six patients with anastomotic aneurysms. Most of these were unexpected and were reason for more critical follow-up or re-operation.

Aorta, Abdominal↗
PubMed1988

Ultrasonic duplex scanning of the prevertebral segment of the vertebral artery in patients with cerebral atherosclerosis.

A routine duplex investigation of the prevertebral segment of the vertebral artery was carried out in 2814 consecutive patients who were suspected for extracranial cerebral atherosclerosis. Depending on local anatomical properties duplex scanning failed to make a decision about the state of the ostium of the vertebral artery in 24% of the cases. This occurred in approximately three quarters of the cases on the left side. With regard to the state of the ostium of the vertebral artery, we compared the data of duplex scanning with those of intra-arterial contrast angiography in 211 patients. For the detection of a stenosis with a diameter reduction of 50% or more at the site of the ostium, duplex scanning has respectively a sensitivity of 0.80, a specificity of 0.92, a positive predictive value of 0.73, and a negative predictive value of 0.94. Eighty-seven percent of the occluded vertebral arteries were correctly identified. In some patients with severe multi-vessel disease, a high-flow or a low-flow state of the vertebral artery or a subclavian steal syndrome did not allow a correct decision with the duplex scanner about the state of the ostium of the vertebral artery. Significant atherosclerotic lesions of the remaining part of the prevertebral segment of the vertebral artery were rare. However, this study shows that duplex scanning of this segment is very well possible and in most cases the results of the non-invasive test were in accordance with those of arteriography.

Female↗
PubMed1988

Benefits of carotid patching: a randomized study.

Advocates of carotid artery patching claim a reduced incidence of recurrent stenosis after endarterectomy. A prospective study was undertaken to determine its value with random selection between primary closure and saphenous vein patching. A consecutive series of 129 carotid endarterectomies was evaluated by duplex scanning at 3, 6, and 12 months after operation. Intravenous digital subtraction angiography (DSA) was performed in the first postoperative days for control of the surgical technique and after 1 year to serve as a reference for the duplex scanning. Sixty-two patients were selected to have primary closure and 67 were chosen for the patching technique. Both groups were identical with regard to risk factors (mean age 63 years, 74% were men, 57% had hypertension, 41% had coronary disease, 37% had peripheral arterial disease, and 9% had diabetes mellitus), side of operation (55% left), symptoms (18% were asymptomatic), and postoperative DSA (81% were normal, 17% had residual lesions, and 2% had occlusions). A complete 1-year follow-up was obtained in 105 cases (81%); duplex scanning showed recurrent stenosis of more than 50% in 12 cases (11%). This was significantly higher after primary closure (10 of 48 patients = 21%) compared with patch closure (2 of 57 = 3.5%; p = 0.006) and also in women (6 of 25 = 24%) compared with men (6 of 80 = 7.5%; p = 0.03). Recurrent stenosis was present in 6 of 11 women with primary closure (55%), 4 of 37 men with primary closure (11%), 2 of 43 men with patching (5%), and none of 14 women with patch closure (0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1987

Detection of unruptured familial intracranial aneurysms by intravenous digital subtraction angiography. Screening of two affected families.

The authors discuss the detection of intracranial aneurysms (IA) by means of intravenous digital angiography (ivDSA) in (a)symptomatic first degree relatives of families in which two or more individuals have IA. ivDSA is an almost noninvasive and low-risk diagnostic procedure. Screening, by means of ivDSA, of two affected families is described. In family I which includes 7 members with proven IA, ivDSA has been carried out in 36 asymptomatic individuals: in one, a 6 X 15 mm aneurysm was found at the left posterior communicating artery (PCoA). In family II, including one member with a proven IA and another with a subarachnoid hemorrhage, ivDSA has been carried out in 4 members: one aneurysm with a diameter of 6 mm was found at the left PCoA. Conventional cerebral angiography (CCA) confirmed both IA's. Neurosurgical treatment followed. The advantages and disadvantages of ivDSA vs. CCA as elective screening procedure in such cases are discussed. Screening of asymptomatic first degree relatives of cases with familial IA by means of ivDSA is strongly advocated.

Adult↗
PubMed1987

Residual lesions and early recurrent stenosis after carotid endarterectomy. A serial follow-up study with duplex scanning and intravenous digital subtraction angiography.

In 109 internal carotid endarterectomies a complete serial follow-up study with ultrasonic duplex scanning was performed at 3, 6, and 12 months after operation. A duplex scan was also performed 2 years postoperatively in 75 cases. Moreover, the state of the endarterectomized carotid bifurcations was documented by intravenous digital subtraction angiography during hospitalization and at 12 months. At 3, 6, 12, and 24 months after operation the rate of significant recurrent stenosis was 6%, 12%, 6%, and 8%, respectively. Approximately half of the arteries with a significant stenosis at 1 year already demonstrated this lesion with intravenous digital subtraction angiography performed 1 week after operation. Persistent significant recurrent stenosis in the remaining arteries was probably the result of excessive myointimal proliferation. This occurred with a higher frequency in women (14.8%) than in men (4.1%). The greater number of the arteries with minimally or mildly disturbed spectral waveforms 3 months after endarterectomy spontaneously normalized or remained stable during the follow-up period. On the other hand, 40% of the arteries with a significant stenosis (diameter reduction of 50% or more) at the three-month control follow-up period increased to a more severe degree of stenosis during the first postoperative year. Most of the operated arteries did not significantly change during the second year.

Carotid Artery Diseases↗
PubMed1987

A comparative study of intravenous digital subtraction angiography and ventilation-perfusion scans in suspected pulmonary embolism.

We observed 102 patients suspected of having pulmonary emboli (PE) who underwent ventilation-perfusion (V/Q) lung scintigraphy and IV digital subtraction angiography (DSA). Only five DSA studies were inadequate for interpretation. In 81 of the remaining 97 patients (83.5 percent) the results of both studies correlated regarding the probability of PE. In 50 patients the results of both studies were highly suggestive of PE; in 31 patients DSA and V/Q were normal or classified as low probability of PE. There was disagreement in 3/97; in 13/97 one or both studies were nondiagnostic. The clinical data of these 16 patients are given. Conventional catheter pulmonary angiography was indicated in 11/102 patients to establish a firm diagnosis of PE. The results of V/Q and DSA correlated in 83 percent (49/59) of patients without chronic obstructive pulmonary disease (COPD) and in 84 percent (32/38) of the patients with COPD.

Adult↗
PubMed1986

Familial association of intracranial aneurysms and multiple congenital anomalies.

The familial occurrence of intracranial aneurysms and the possible relationship with connective tissue disease are discussed. We studied a large family in which seven members presented with aneurysms. Another family member presented with a subarachnoidal hemorrhage. Two other family members each presented with Marfan's syndrome and an unclassified multiple congenital anomalies syndrome, respectively. The multiplicity of the aneurysms in four members is in excess of that found in sporadic or familial cases with intracranial aneurysms. We suggest a common cause, eg, a connective tissue disorder for both the intracranial aneurysms, the Marfan's syndrome, and the unclassified syndrome.

Abnormalities, Multiple↗
PubMed1983

A new angiographic technique for asymptomatic hereditary glomus screening.

This paper reports the findings of a new noninvasive technique for the study of blood vessels - digital vascular imaging (D.V.I.). A patient suspected of asymptomatic familial glomus tumor was investigated using D.V.I. Two glomus caroticum tumors (one very small) were found with this new technique. The D.V.I. technique allows one to study vascular lesions in the head and neck without hospitalizing the patient. Digital angiography is an important improvement in screening and follow-up of patients with glomus tumors.

Cerebral Angiography↗
PubMed1983

Digital subtraction angiography of the pulmonary arteries for the diagnosis of pulmonary embolism.

A comparative study of radionuclide scanning (perfusion studies in all 18 patients and ventilation studies in 9) and digital subtraction angiography (DSA) was performed in 18 patients with suspected pulmonary thromboembolism. In 17 patients good visualization of the arteries was obtained with DSA; 10 of these patients had no pre-existing lung disease, and 7 had chronic obstructive pulmonary disease (COPD). The information provided by DSA in this small group was equal to or better than that of scintigraphy, especially in patients with COPD, and the reliability of DSA was superior to that of radionuclide scintigraphy. Methods for preventing motion artifacts with DSA are also described.

Adult↗
PubMed1983

Digital video subtraction angiography and duplex scanning in assessment of carotid artery disease: comparison with conventional angiography.

Digital video subtraction angiography (DVSA) and duplex scanning were compared to conventional angiography with regard to their accuracy in quantifying internal carotid artery disease. A classification of 108 carotid arteries available for comparison was made into five groups: normal (14), stenosis to 20% (15), stenosis from 20% to 49% (19), stenosis from 50% to 99% (44), and occlusion (16). The overall agreement corrected for chance (K) for DVSA was 0.738 +/- (SE) 0.049, which was better than for duplex scanning (K = 0.610 +/- 0.055). For hemodynamically significant disease (greater than or equal to 50% diameter reduction), both techniques were highly accurate: DVSA had a sensitivity of 95% (57/60) and a specificity of 92% (44/48); the sensitivity of duplex scanning was also 95% (57/60) and the specificity 85% (41/48). The accuracy in differentiating between high-grade stenosis and occlusion was 98% (59/60) for duplex scanning and 100% (60/60) for DVSA. The most prominent limitation of duplex scanning was its overestimation of disease in normal and minimally diseased arteries. Its specificity for ruling out any degree of disease was only 21% (3/14). DVSA had a poor predictive value of a normal test, 55% (12/22), and was more than one category wrong seven times, while this occurred only three times for duplex scanning. At the present time carotid endarterectomy without conventional angiography is only advocated when there is complete agreement between DVSA and duplex scanning.

Angiography↗
PubMed1983

Digital vascular imaging in extra- and intracranial artery disease and of abdominal arteries.

Digital vascular imaging is a new technique for vessel investigation. This article describes the application of the method with intravenous administering of the contrast material for the intra- and extracranial arteries and for the abdominal vessels. The equipment and the conditions to obtain good images are described. The indications for investigation of the vessels are given with the preliminary results. The advantages of the technique are mentioned.

Abdomen↗
PubMed1982

Left ventricle evaluation by digital video subtraction angiocardiography.

The usefulness of digital video subtraction angiocardiography (DVSA) using the time-interval difference (TID) mode for measuring ejection fraction and wall motion of the left ventricle was assessed in 20 patients after intravenous injection of contrast material. These 20 cases represented the TID examinations with the best image quality, and were selected from a total of 70 TID examinations. Images were obtained using a prototype digital vascular imaging unit. Conventional left ventriculography was also performed. A good correlation was found between the two methods in determining the ejection fraction (0.81) and the motion of the anterior wall and apex (0.89). The correlation was not as good for determining the movement of the inferior ventricular wall (0.62). This was due to the difficulty of separating the inferior ventricular wall from the left hemidiaphragm.

Adult↗