Risk factors for premature atherosclerosis.
(33/2636)
OBJECTIVES: to investigate the prevalence of risk factors in patients with premature atherosclerosis. DESIGN: retrospective controlled study. MATERIALS: 135 consecutive patients with premature atherosclerosis /= 65 years (group II) with atherosclerosis. Statistical analysis was performed with Chi-squared test and logistic regression analysis. RESULTS: group I versus group II: diabetes 11% vs. 27% (p=0.001), smoking 84% vs. 67% (p=0.002), hypertension 36% vs. 58% (p=0.001), hypercholesterolaemia 47% vs. 34% (p=0.04), family history of cardiovascular disease 53% vs. 42% (p=0.08). In group I hyperhomocysteinaemia was present in 24 of the 108 patients tested, anticardiolipin antibodies were present in four of the 34 tested and coagulation abnormalities were found in four of the 22 patients tested. CONCLUSION: the difference in the prevalence of the different risk factors between the two groups suggests that either certain risk factors are more likely to cause premature atherosclerosis, or that other risk factors must be present in addition to the known risk factors in order to induce premature atherosclerosis. (+info)
Increased sympathetic nerve activity in renovascular hypertension.
(34/2636)
BACKGROUND: Increased sympathetic nerve activity may contribute to the progression of renovascular hypertension. Because previous results have been inconclusive, we investigated whether renovascular hypertensives show increased total and regional sympathetic nerve activity. METHODS AND RESULTS: Sixty-five patients underwent renal angiography and measurements of plasma renin activity and angiotensin II in conjunction with estimation of sympathetic nerve activity by means of radiotracer dilution and intraneural recordings of muscle sympathetic nerve activity (MSNA). Age-matched healthy subjects (n=15) were examined for comparison. Total body norepinephrine (NE) spillover, an index of overall sympathetic nerve activity, was increased by 100% and MSNA by 60% in the hypertensive patients compared with healthy subjects (P<0.01 for both). A subgroup of 24 patients with well-defined renovascular hypertension (cured or improved hypertension after renal angioplasty) showed similar increases in total body NE spillover compared with the group at large. Patients with arterial plasma renin activity and angiotensin II levels above median had higher values for total body NE spillover than patients below median (P<0.01). CONCLUSIONS: This study unequivocally demonstrates elevated sympathetic nerve activity in patients with renovascular hypertension. The adrenergic overactivity may contribute to the blood pressure elevation and perhaps also to the high cardiovascular mortality in renovascular hypertension. (+info)
Fate of the stented arterial duct.
(35/2636)
BACKGROUND: The technical aspects of ductal stenting have been reported, but little is known of the fate of the duct after stent implantation. METHODS AND RESULTS: Nineteen patients underwent stent implantation to maintain ductal patency. Eight had hypoplastic left heart (HLH) syndrome, 10 had pulmonary atresia, and 1 had tricuspid atresia. Median survival with HLH was 57 (12 to 907) days. Stent implantation was successful in all cases of HLH, but there were no long-term survivors. Two well-palliated infants died at transplantation. Median survival with duct-dependent pulmonary flow was 183 (0 to 1687) days, with 3 patients well at latest follow-up (56, 55, and 9 months, respectively). There were 2 operative deaths due to ductal spasm and 4 late deaths, 1 due to duct thrombosis, 1 due to chronic lung disease, and 2 of unknown cause. Stent implantation failed in 4 of the 11 cases. Assessment of endothelialization was possible in 13 cases; the stent was partially covered in 3 and fully endothelialized in all 10 cases assessed >8 weeks after implantation. In patients stented for inadequate pulmonary flow, ductal intimal hyperplasia occurred by 9 months in all 3 survivors but responded to repeated dilation. CONCLUSIONS: Ductal stenting cannot be recommended. In patients with HLH, it provides only short-term palliation even when combined with pulmonary artery banding. With duct-dependent pulmonary blood flow, the procedure carries high risk, and duration of palliation is poor. In patients with bilateral ducts and absent central pulmonary arteries, good palliation may be achieved, but repeated angioplasty is necessary to counteract intimal hyperplasia. (+info)
A picture archiving and communications system featuring multiple monitors using Windows98.
(36/2636)
We present an effective approach to manage, review, and distribute Digital Imaging and Communications in Medicine (DICOM) images with multiple monitors using Windows98 (Microsoft Corp, Redmond, WA) that can be implemented in an office-based setting. Computed tomography (CT), magnetic resonance imaging (MRI), and angiographic DICOM images were collected, compressed, and stored using Medweb (Medweb, Inc, San Francisco, CA) software. The Medweb server used the Linux/UNIX operating system on a Pentium 333-MHz processor with 128 MB of RAM. Short-term storage capacity was about 2 weeks with routine usage of an 11-GB hard drive. Images were presented for reading on a dual-monitor Windows98 Pentium display station with 160 MB of RAM using a Medweb/Netscape (Netscape Communications Corp, Mountain View, CA) viewer. There was no significant discrepancy in diagnosis between electronic and conventional film images. Mean reading time for 32 cases was 118 seconds. The Medweb JAVA plug-in viewer loaded the first image within 30 seconds of selecting the case for review. Full uncompressed 16-bit images allowed different window settings to better assess for pathology. Multiple monitors allowed viewing various hanging protocols. Cine viewing was also possible. Key diagnostic images were electronically transmitted to referring physicians. On-call radiologists were able to access images through the Internet. By combining Medweb, DICOM, and web-browser software using desktop personal computers (PCs), an easily accessible picture archiving and communications system (PACS) is available to radiologists and referring physicians. Multiple monitors are easily configured and managed using Windows98. This system can sustain changes and can be extended to provide variable functions using inexpensive PCs. (+info)
New duplex ultrasound scan criteria for managing symptomatic 50% or greater carotid stenosis.
(37/2636)
PURPOSE: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) showed that selected patients benefited from surgery when their carotid artery was 50% or more stenosed. This study assessed the accuracy of color-flow duplex ultrasound scanning (DUS) parameters to detect 50% or greater carotid artery stenosis and to determine the situations in which carotid endarterectomy (CEA) without angiography could be justified. METHODS: From March 1, 1995, to December 1, 1995, all patients considered for CEA were studied with DUS and carotid angiography. Results of the two tests were blindly compared. DUS measurements of internal carotid artery (ICA) peak systolic velocity (PSV), end diastolic velocity, and ratio of the ICA to common carotid artery PSV (ICA/CCA) were subjected to receiver operator characteristic curve analysis to determine the most accurate criterion predicting 50% or greater angiographic stenosis. The criterion for identifying patients for CEA without angiography was selected from criteria with a high positive predictive value (PPV) and sensitivity. RESULTS: A total of 188 carotid bifurcations were available for comparison. A PSV (ICA/CCA) of 2 or higher was the most accurate criterion for detection of 50% or greater stenosis, with an accuracy rate of 93% (sensitivity, 96%; specificity, 89%; PPV, 92%). A PSV (ICA/CCA) of 3.6 or higher was the best criterion for identifying candidates for CEA who had not undergone earlier angiography, with PPV, sensitivity, specificity, and accuracy rates of 98%, 77%, 98%, and 86%, respectively. CONCLUSION: These redefined criteria detect the NASCET-defined threshold level of 50% or greater ICA stenosis, above which CEA results in stroke reduction. A management algorithm based on these criteria should help to minimize both angiography and unnecessary intervention. (+info)
Surgical renal artery reconstruction without contrast arteriography: the role of clinical profiling and magnetic resonance angiography.
(38/2636)
PURPOSE: Contrast arteriography is the accepted gold standard for diagnosis and treatment planning in patients with atherosclerotic renovascular disease (RVD). In this study, the results of a selective policy of surgical renal artery reconstruction (RAR) with magnetic resonance angiography (MRA) as the sole preoperative imaging modality are reviewed. METHODS: From May 1993 to May 1998, 25 patients underwent RAR after clinical evaluation, and aortic/renal MRA performed with a gadolinium-enhanced and 3-dimensional phase contrast technique. Clinical presentations suggested severe RVD in all patients and included poorly controlled hypertension (16 patients), hospitalization for hypertensive crises and/or acute pulmonary edema (13), and deterioration of renal function within one year of operation (15). Thirteen patients had associated aortic pathologic conditions (12 aneurysms, 1 aortoiliac occlusive disease), and eight of these patients also underwent noncontrast computed tomography scans. Significant renal dysfunction (serum creatinine level, >/=2.0 mg/dL) was present in all but 4 patients with 14 of 25 patients having extreme (creatinine level, >/=3.0 mg/dL) dysfunction. RESULTS: Hemodynamically significant RVD in the main renal artery was verified at operation in 37 of 38 reconstructed main renal arteries (24/25 patients). A single accessory renal artery was missed by MRA. RAR was comprehensive (bilateral or unilateral to a single-functioning kidney) in 21 of 25 patients and consisted of hepatorenal bypass graft (3 patients), combined aortic and RAR (13 patients), isolated transaortic endarterectomy (8 patients), and aortorenal bypass graft (1 patient). Early improvement in both hypertension control and/or renal function was noted in 21 of 25 patients without operative deaths or postoperative renal failure. Sustained favorable functional results at follow-up, ranging from 5 months to 4 years, were noted in 19 of 25 patients. CONCLUSION: MRA is an adequate preoperative imaging modality in selected patients before RAR. This strategy is best applied in circumstances where the clinical presentation suggests hemodynamically significant bilateral RVD and/or in patients at substantial risk of complications from contrast angiography. (+info)
Bubble contrast echocardiography in detecting pulmonary arteriovenous shunting in children with univentricular heart after cavopulmonary anastomosis.
(39/2636)
OBJECTIVES: We sought to compare bubble contrast echocardiography and pulmonary angiography in detecting pulmonary arteriovenous malformation (PAVM) in children with cavopulmonary anastomosis (CPA), and to examine anatomic and physiologic variables associated with the development of PAVM. BACKGROUND: Development of PAVM in patients with CPA may cause profound cyanosis. Pulmonary arteriovenous malformation has been traditionally diagnosed by pulmonary angiography with reported incidence of 20% to 25% in patients with CPA. METHODS: Fourteen patients (age 1.1 to 12.6 years) with any forms of CPA and normal pulmonary venous drainage formed the study population. All patients underwent cardiac catheterization and pulmonary angiography. Bubble contrast echocardiographic studies were performed with injection of 10 ml of agitated saline solution into branch pulmonary arteries. Transthoracic echocardiograms using an apical view were performed to assess the appearance of bubble contrast in the systemic ventricles. We compared the results of pulmonary angiograms and contrast echocardiograms, and findings of contrast echocardiograms between lungs with hepatic venous blood flow and lungs without hepatic venous blood. RESULTS: Ten of the 14 patients (71%) had positive contrast echocardiographic studies, compared with three (21%) detected by pulmonary angiograms (p = 0.01). No difference was found in pulmonary artery pressure, transpulmonary gradient or presence of heterotaxy syndrome between patients with positive contrast echocardiographic studies and patients with negative studies. However, patients with positive contrast echocardiograms tended to have lower oxygen saturation (81%) and higher hemoglobin (16.4 g/dl) compared with patients with negative studies (88% and 14.7 g/dl, p = 0.10 and p = 0.18 respectively). Patients with Glenn shunt or unidirectional Fontan had higher incidence of PAVM (10/11) compared with patients with classic or lateral tunnel Fontan (0/3, p = 0.01). All 12 lungs with no perfusion of hepatic venous blood had positive contrast echocardiographic studies. Lungs with no hepatic venous blood flow were more likely to develop PAVM compared with lungs with hepatic venous blood flow (12/12 and 3/16 respectively, p < 0.01). CONCLUSIONS: Bubble contrast echocardiography is more sensitive in detecting PAVM compared with pulmonary angiography. The prevalence of PAVM in patients with CPA may be much higher than what had been reported previously. Lungs with no hepatic venous blood flow are more likely to develop PAVM than lungs with hepatic venous blood flow. (+info)
Branching patterns of intramural coronary vessels determined by microangiography using synchrotron radiation.
(40/2636)
The intramural coronary artery (IMCA) with a diameter of 50-500 micrometers is critical for blood supply to the inner layers of heart muscle. We introduced digital measurement to microangiography using monochromatic synchrotron radiation and quantified branching patterns of the IMCA, the epicardial coronary artery (EPCA), and the distal ileal artery (DIA). The pre- and postbranching diameters were measured (95-1,275 micrometers) in seven dogs. A typical arterial segment divided into two nearly equivalent branches, and a regression line of daughter-to-mother diameter plots was almost identical among the EPCA (y = 0.838x - 16.7 in micrometers), IMCA (y = 0.737x - 2.18), and DIA (y = 0.755x + 8.63). However, a considerable difference was present at a segment where a proximal IMCA branched off from an EPCA (y = 0.182x + 90.2). Moreover, a proximal IMCA diameter had no relationship to the branching order from an EPCA. The precision of this method was confirmed by the good correlation of diameter measurements between two independent observers (r = 0.999, y = 1.02x - 1.07). In conclusion, using digital microangiography we demonstrated that the self-similar branching pattern of coronary arteries was discrete at the connection between the IMCA and EPCA. (+info)