Commentary: Shoot the renals!

Atherosclerotic renal artery stenosis (ARAS) is a growing dilemma. The condition is increasingly common and can promulgate hypertension and result in renal failure. However, patients with ARAS generally die owing to their coronaries or cerebral vessels. Intervention, by stenting or angioplasty is beloved and believed, but not proved. The American Heart Association has recently published guidelines regarding patients at high risk for ARAS who are potential candidates for revascularisation. Since this phraseology includes practically every patient with atherosclerosis, these guidelines appear ill advised.

Preparation of protected peptidyl thioester intermediates for native chemical ligation by Nalpha-9-fluorenylmethoxycarbonyl (Fmoc) chemistry: considerations of side-chain and backbone anchoring strategies, and compatible protection for N-terminal cysteine*,+

Native chemical ligation has proven to be a powerful method for the synthesis of small proteins and the semisynthesis of larger ones. The essential synthetic intermediates, which are C-terminal peptide thioesters, cannot survive the repetitive piperidine deprotection steps of N(alpha)-9-fluorenylmethoxycarbonyl (Fmoc) chemistry. Therefore, peptide scientists who prefer to not use N(alpha)-t-butyloxycarbonyl (Boc) chemistry need to adopt more esoteric strategies and tactics in order to integrate ligation approaches with Fmoc chemistry. In the present work, side-chain and backbone anchoring strategies have been used to prepare the required suitably (partially) protected and/or activated peptide intermediates spanning the length of bovine pancreatic trypsin inhibitor (BPTI). Three separate strategies for managing the critical N-terminal cysteine residue have been developed: (i) incorporation of N(alpha)-9-fluorenylmethoxycarbonyl-S-(N-methyl-N-phenylcarbamoyl)sulfenylcysteine [Fmoc-Cys(Snm)-OH], allowing creation of an otherwise fully protected resin-bound intermediate with N-terminal free Cys; (ii) incorporation of N(alpha)-9-fluorenylmethoxycarbonyl-S-triphenylmethylcysteine [Fmoc-Cys(Trt)-OH], generating a stable Fmoc-Cys(H)-peptide upon acidolytic cleavage; and (iii) incorporation of N(alpha)-t-butyloxycarbonyl-S-fluorenylmethylcysteine [Boc-Cys(Fm)-OH], generating a stable H-Cys(Fm)-peptide upon cleavage. In separate stages of these strategies, thioesters are established at the C-termini by selective deprotection and coupling steps carried out while peptides remain bound to the supports. Pilot native chemical ligations were pursued directly on-resin, as well as in solution after cleavage/purification.

An Internet-based simulation model for nitrogen management in agricultural settings

Complex chemical, physical, and biological processes mediate nitrogen (N) transformations and movement during agricultural production, making the optimization of fertilizer use and environmental protection exceedingly difficult. Various computer models have been developed to simulate the site-specific fate and transport of N resulting from different crop production scenarios, but these models are very complex and difficult to use for most farmers, consultants, and conservationists. In an effort to facilitate access and simplify the use of sophisticated models, the U.S. Department of Agriculture (USDA) has developed an Internet-based nitrogen analysis tool. Based on the Nitrate Leaching and Economic Analysis Package (NLEAP), the Web site allows a user to conduct multiyear N simulation modeling specific to a crop field. Servers handle much of the required data assembly and formatting, thus sparing the user"s resources. Model runs are executed on the servers and the results are transmitted to the user. This new tool is presented along with early implementation results.

Determination of renal arterial stenosis severity: comparison of pressure gradient and vessel diameter

PURPOSE

To determine the hemodynamic significance of arteriographically detected renal arterial stenosis by obtaining pressure gradients with a miniaturized pressure guide wire.

MATERIALS AND METHODS

Forty-six renal arterial stenoses in 38 patients were assessed in terms of severity and then subjected to gradient determination before and after angioplasty. The patients (mean age, 63 years) had a mean serum creatinine value of 1.3 mg/dL +/- 0.4 (114.9 micromol/L +/- 35.4 [SD]) and required on average three medications for blood pressure control. The mean degree of stenosis diameter was 51% +/- 17 (range, 12%-85%).

RESULTS

The systolic and mean arterial pressure gradients with and those without vasodilatation were highly correlated with stenosis severity, systolic blood pressure, and serum creatinine as a curvilinear fit (r = 0.9, P <.01). At 50% stenosis severity, the mean pressure gradient was 22 mm Hg.

CONCLUSION

Patients with a pressure gradient greater than 20 mm Hg should be good candidates for renal arterial dilatation, and use of the pressure guide wire will facilitate interventional decisions.

[Renovascular illness: prevalence and therapy in patients with coronary heart disease]

To explore the relationship between coronary artery disease and renal vascular disease, we performed renal arterial angiography in 609 patients undergoing coronary angiography for suspected coronary artery disease. We defined renal artery stenosis as nonsignificant (< 40%), borderline (40-60%) and significant (> 60%). One-hundred fifty-two patients had renal artery stenosis, while 457 did not. Two-hundred and ten patients had no coronary disease; of these, only 9 had renal artery stenosis. On the other hand, the 143 patients with renal artery stenosis, when subdivided, had similar degrees of coronary disease; three vessel disease was significantly more common than one or two vessel disease in all groups. Renal artery stenosis of all severity degrees was associated with common atherosclerotic risk factors. However, hypertension was not a clue to the presence of renal artery stenosis. To evaluate the effect of percutaneous revascularization on hypertension and renal function all 51 patients with significant renal artery stenosis were treated by primary stent implantation and were followed up for 6 months. Stent implantation showed a marked decrease in systolic and diastolic blood pressure (163 +/- 30 to 145 +/- 17 and 93 +/- 18 to 83 +/- 10 mmHg; p = 0.008) with a decrease in the amount of antihypertensive medication but without beneficial effect on serum creatinine during follow-up (1.46 +/- 0.70 mg/dl to 1.39 +/- 0.58 mg/dl, p = ns). We conclude that renal artery stenosis of any severity is strongly suggestive of three vessel coronary artery disease. The fact that renal stenting lowers blood pressure decreases antihypertensive drugs and increases medication flexibility in patients with coronary artery disease would support the notion of revascularization in patients with significant stenoses.

Clinical and angiographic outcome in patients with in-stent restenosis and repeat target lesion revascularisation in small coronary arteries

OBJECTIVE

To evaluate the clinical and angiographic outcome in patients with in-stent restenosis in small coronary arteries and repeat target lesion revascularisation.

DESIGN

Patients with in-stent restenosis in coronary arteries < or = 2.85 mm were eligible for the study and underwent target lesion revascularisation. Clinical and angiographic variables were assessed during a six month follow up period.

RESULTS

73 patients with 79 lesions were treated by percutaneous transluminal coronary angioplasty (47%), excimer laser angioplasty (25%), or restenting (28%). The mean (SD) reference diameter before target lesion revascularisation was 2.12 (0.5) mm. Procedural success was achieved in all cases, but 57% of the patients had restenosis after six months. The rate of further restenosis was higher with laser angioplasty (78%) than with restenting (47%) or balloon angioplasty alone (49%, p < 0.05).

CONCLUSIONS

Treatment for in-stent restenosis in small coronary arteries is feasible and safe, with a second restenosis rate comparable to large coronary artery series. The strategy of target lesion revascularisation influences further in-stent restenosis, with an increased rate with laser angioplasty compared with restenting and repeat dilatation alone.

Postcatheterization pseudoaneurysms and arteriovenous fistulas: repair with percutaneous implantation of endovascular covered stents

PURPOSE

To assess the effectiveness and safety of endovascular covered stents in the management of pseudoaneurysms and arteriovenous fistulas after cardiac and vascular catheterization.

MATERIALS AND METHODS

Twenty-six endovascular covered stents were used to repair 16 pseudoaneurysms, nine arteriovenous fistulas, and one combined lesion after femoral arterial puncture for diagnostic coronary angiography and/or angioplasty. Fistulas and aneurysms were in the superficial femoral artery in 16 cases, in the deep femoral artery in six cases, and in the common femoral artery in four cases. Implantation was performed from the opposite femoral artery in most cases. It was not possible to treat three additional cases transcutaneously for technical reasons (three of 29 cases).

RESULTS

Percutaneous closure of the lesions with an endovascular covered stent was successful in 26 of 29 cases. Initial follow-up showed good stent patency. Two major complications were observed after stent implantation. During follow-up (about 1 year in 23 of 26 patients [88%]), stent thromboses were detected in four of 23 patients (17%) with follow-up color duplex flow imaging.

CONCLUSION

Implantation of endovascular covered stents is an effective and safe method for the percutaneous closure of pseudoaneurysms and arteriovenous fistulas. Thus, endoluminal vascular repair with covered stents offers an alternative therapeutic approach to vascular surgery in selected patients.

Treatment of carotid artery stenosis by elective stent placement instead of carotid endarterectomy in patients with severe coronary artery disease

Patients with concomitant cardiac and cerebrovascular disease undergoing revascularization procedures are at high risk of both, cardiac and cerebrovascular complications. The purpose of our study was to evaluate the feasibility of prior elective carotid artery stenting as an alternative treatment procedure to carotid endarterectomy (CEA) in patients with concomitant coronary artery disease (CAD), who clearly needed coronary revascularization. We offered extracranial internal carotid stenting to 85 patients with 89 significant carotid stenoses. Out of these, 19 patients were symptomatic. The quantitative mean reduction in diameter was 77 +/- 11%. Stent implantation was successful in 88 lesions. Two disabling major and 3 reversible minor strokes occurred periprocedurally. Three patients showed asymptomatic restenosis and stent deformation was detected in 2 patients. Based on this experience, carotid stenting in high risk patients with severe coronary artery disease is feasible and safe and might be indicated as an alternative procedure for combined surgery.

Percutaneous treatment of pseudoaneurysms and arteriovenous fistulas after invasive vascular procedures

Development of femoral artery pseudoaneurysms and arteriovenous fistulas represents a continuing problem after vascular diagnostic and interventional procedures. For most patients, ultrasound-guided compression is an effective method of treating such complications. However, in patients requiring a continuous anticoagulant regimen, in those with large arteriovenous fistulas or in patients suffering from painful groin hematomas, compression repair is less successful. We therefore assessed the feasibility, efficacy, and long-term results of interventional percutaneous treatment of these complications. In a 40-month period, we treated 53 consecutive patients with 30 pseudoaneurysms, 21 arteriovenous fistulas, and 2 combined lesions. The intervention was successful in 47 patients: 32 lesions were treated by implantation of covered stents, 14 by embolization techniques, and 1 by a combined procedure, surgical repair being necessary only in 6 patients. After a clinical and ultrasonic follow-up of 301 +/- 280 days, we noticed four late stent occlusions, especially in patients with poor peripheral runoff. Lesions with a distinct connection channel to the vessel lumen should be treated by coil embolization. In lesions originating from the femoral bifurcation with a broad base, surgical repair is necessary. Stenting of the superficial femoral artery with poor runoff should be avoided. Our results suggests that percutaneous closure of false aneurysms and arteriovenous fistulas after invasive procedures with unsuccessful ultrasonic compression repair is an attractive alternative to surgical treatment.

A novel isoform of the smooth muscle cell differentiation marker smoothelin

Studies on smooth muscle cell differentiation and those on vascular development in mouse and humans have long been hampered by the lack of suitable markers. Here we describe a novel, large isoform of smoothelin, a structural protein of differentiated, contractile smooth muscle cells. The protein, which is highly conserved in mouse and humans, shows homology with other cytoskeleton-associated smooth muscle cell proteins and contains an actinin-type actin-binding domain. Northern blot analysis from various mouse organs identified short and long smoothelin mRNA forms, which exhibit distinct tissue expression patterns. The short form is highly expressed in visceral muscle tissues such as intestine and stomach and is not detectable in brain, while the long mRNA form is expressed in all vascularized organs. These results may provide new tools and approaches to study both smooth muscle cell differentiation and proliferative vascular disease.

Ostial renal artery stent placement for atherosclerotic renal artery stenosis in patients with coronary artery disease

To test the utility of endoprosthetic treatment for ostial renal artery stenosis, and to examine blood pressure and its treatment, serum creatinine, and restenosis rate, 44 ostial renal stent placements were performed in 30 patients with concomitant coronary artery disease, arterial hypertension, and the indication for angiotensin converting enzyme (ACE) therapy. There was a marked decrease in systolic and diastolic blood pressure (163+/-30 to 145+/-17 and 93+/-18 to 83+/-10 mm Hg; P < 0.008) with a decrease in number of medication (3.2+/-0.9 to 2.8+/-1.0; P = 0.005). In 5 out of 8 patients not receiving an ACE inhibitor, this drug could be added. Serum creatinine changed from 1.46+/-0.7 mg/dl to 1.39+/-0.58 mg/dl (P = ns). Three patients showed restenosis (12.5%). Ostial stenting lowers blood pressure, decreases antihypertensive drugs and increases medication flexibility.

Elective stenting of carotid artery stenosis in patients with severe coronary artery disease

AIMS

To evaluate the feasibility and safety of elective carotid stent implantation in patients with carotid stenoses and concomitant coronary artery disease, as an alternative to combined carotid and coronary surgery.

METHODS

We treated 50 patients with >70%, stenoses in 53 carotid arteries with balloon angioplasty followed by elective stent implantation. All patients had severe coronary artery disease, and/or mitral insufficiency, aortic stenosis, rhythm disorders or generalized arteriosclerosis. In three patients the opposite carotid artery was occluded; nine patients had bilateral stenoses of which two received stents bilaterally.

RESULTS

Fifty-six successful stent implantations (42 Wallstents, eight BeStents, two AVE-Microstents, one Palmaz Schatz stent, three Sito stents) were performed, reducing the baseline percent stenosis from 78 +/- 18%, to 13 +/- 11%. Complications included three transient ischaemic attacks, one minor and one major stroke. Follow-up was available for 46 patients over a mean of 10 months. Three asymptomatic restenoses and one deformation of a BeStent occurred.

CONCLUSION

Our preliminary results indicate that carotid artery stenting in patients with concomitant severe coronary artery disease is feasible, safe, and may be an alternative to combined carotid and coronary surgery.

Relation between arteriosclerosis in the coronary and renal arteries

This study analyzes the severity of coronary artery disease in terms of the severity of renal artery disease in 609 patients undergoing coronary and renal angiography. The presence of renal artery disease of any severity is strongly suggestive of advanced coronary artery disease.

Stent implantation in patients with superior vena cava syndrome

OBJECTIVE

The purpose of this study was to determine the feasibility of using Wallstent implantation to treat superior vena cava syndrome due to malignant tumors.

SUBJECTS AND METHODS

Digital subtraction angiography showed obstruction of the superior vena cava in 13 patients who then underwent transluminal dilatation and Wallstent implantation. The patients were treated with IV heparin and monitored in the emergency department. Thereafter, they were treated with a platelet inhibitor for 4 weeks.

RESULTS

Because their signs and symptoms improved, patients were able to resume radiation therapy, chemotherapy, or both. One patient died of cardiac arrhythmia 1 day after stent placement. Although eight patients have subsequently died of their bronchial or thyroid gland tumors, superior vena cava syndrome did not recur in any patient.

CONCLUSION

Percutaneous implantation of Wallstent endoprostheses provides excellent palliation for superior vena cava syndrome.

Evaluation of an intelligent seat system

This study was conducted to evaluate the effect of an intelligent seat system, a microprocessor-based interactive seat that automatically adjusts itself to fit a seated individual by making pressure-sensitive adjustments on its own. First, a standard American automobile seat ('baseline' seat) was assessed for comfort. Subjective ratings of comfort, pressure distribution and seated anthropometric measurements were recorded for 20 test subjects. These measurements were recorded while the subjects maintained a simulated driving position in a seat buck. The comfort scale was based on a rating of 1 to 10, with 1 corresponding to 'very poor' and 10 corresponding to 'very good.' Based on a nonlinear, multiple regression model that had been previously developed, the comfort rating of the seat was predicted based on the subjective ratings and the recorded values of 450 pressure measurements from 20 subjects. The predicted comfort value was 7.46 for the baseline seat. Following the baseline assessment, the intelligent seat system was installed into the standard American automobile seat. The objective and subjective assessments were then repeated for 17 subjects and the new predicted comfort rating was 8.06. A t-test performed on the subjective and objective measures indicated that this was a significant improvement in seat comfort. Overall, subjects felt the self-adjusting seat was more customized and more comfortable, providing a better fit.

Echocardiographic manifestations of mediastinal masses compressing or encroaching on the heart

Because of its central position within the thorax, the heart can be encroached upon by masses originating in either anterior, posterior, or superior mediastinum. A distinction may be made between (A) Encroachment: distortion or partial displacement of one or more cardiac chambers by a contiguous mediastinal mass, without adverse hemodynamic effects, and (B) Compression: resulting in clinical manifestations similar to tamponade. Transthoracic and, recently, transesophageal echocardiography have been found useful in detecting mediastinal masses, the information obtained being complementary or preliminary to more complete imaging by CT or MRI. Anterior masses tend to compress the right heart chambers; posterior masses impinge on or compress the left atrium or ventricle, particularly the former. The wide variety of echographic appearances are briefly reviewed. Recently TEE has made it possible to diagnose masses obstructing the superior vena cava or pulmonary veins. A common, though little known, type of posterior mediastinal encroachment that echocardiographers need to be aware of is that of abnormal esophageal/gastric masses including hiatus hernia and esophageal carcinoma, which have typical two-dimensional echo features and may sometimes simulate left atrial masses.

Assessment of echocardiographic left ventricular mass before and after acute volume depletion

Left ventricular mass calculations are often performed to assess the need or effectiveness of antihypertensive drug therapy. However, there are multiple potential errors that may affect the accuracy of these calculations, which can possibly include acute changes in preload. Therefore, to assess the hypothesis that acute volume depletion might alter calculated left ventricular mass, 15 normotensive healthy male volunteers underwent standard M-mode echocardiographic evaluations (at the level of the chordae tendineae guided by two-dimensional echocardiography) before and 2 h after 40 mg of intravenous furosemide. One patient was eliminated due to hypotension prior to the final echocardiogram. The echocardiograms were blinded to patient identity and the time sequence and read separately by two investigators. Four to five cycles were read per echocardiogram by each investigator. All values measured were the mean of the two investigators. Echocardiographic measurements were derived by both the American Society of Echocardiography and Penn conventions. An average urine volume of 1728 mL was collected, and the mean weight change 2 h after furosemide administration was 1.78 kg (P = .001). Penn left ventricular diastolic diameter (1.8 mm, P = .015) and left ventricular mass index (10 g/m2, P = .04) were significantly decreased; however, there was no significant change in septal, posterior, or relative wall thicknesses. As it is unreasonable to believe that acute remodeling of the left ventricle resulted in a decline in left ventricular mass in 2 hours, it is concluded that acute volume changes resulted in a decrease in left ventricular mass measurement due to the influence of diastolic diameter on the calculation of cardiac mass.

Assessment of late potentials in patients with essential hypertension by the signal-averaged electrocardiogram with five year follow-up

Both the Framingham and Manitoba Heart Studies have identified electrocardiographic left ventricular (LV) hypertrophy (LVH) as a risk factor for sudden cardiac death. Low amplitude ventricular late potentials in the terminal part of ventricular activation have been associated with sustained ventricular tachycardia and have identified those at risk for sudden cardiac death. Therefore, we prospectively examined 23 essential hypertensives without known symptomatic coronary heart disease by two-dimensional echocardiography and signal averaged electrocardiograms (SAECGs) for the detection of ventricular late potentials. The SAECG vector-magnitude complex measurements included the total duration of the complex (QRSd), the voltage in the last 40 ms (V40), and the duration of low amplitude signals < 40 microV in the terminal portion of the complex (LASd). Echocardiographic parameter means were: LV diastolic diameter = 46.0 +/- 4.5 mm, combined septal and posterior wall thickness = 23.3 +/- 4.2 mm, LV mass (Woythaler method) = 235.1 +/- 69.1 g, LV mass (Penn method) = 199.5 +/- 55.3 g and ejection fraction = 63.9 +/- 6.2%. SAECG measurement means were QRSd = 88.2 +/- 9.9 ms, V40 = 63.1 +/- 34.7 microV RMS, and LASd = 23.5 +/- 10.0 ms. No echocardiographic parameter correlated with SAECG duration; however, age correlated with QRSd (r = 0.48, P = 0.02). Posterior wall thickness (r = -0.43, P = 0.04), LV mass index (r = -0.44, P = 0.03) and LV mass/height (r = -0.49, P = 0.02) inversely correlated with LASd.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term severe pulmonary hypertension associated with right atrial myxoma

An 18-year-old black woman presented with marginally compensated right heart failure, severe pulmonary hypertension, tricuspid incompetence, and right atrial myxoma. Catheterization suggested a substantial reactive component to her P-HTN, especially to nifedipine. Initial management consisted of excision of two right atrial myxomas and tricuspid annuloplasty, and postdischarge management with nifedipine, 30 mg four times daily. Emergency pulmonary thromboendarterectomy was required two weeks later for acute cor pulmonale. It is suggested that concomitant procedures are mandatory in this setting because of the otherwise accelerated adverse pathophysiology of obliterative pulmonary vascular obstructive disease.

Case report: acute presentation of pseudo myocardial infarction secondary to metastatic cancer

Electrocardiographic ST segment changes that mimic myocardial infarction (MI) may occur secondary to metastatic carcinoma. Presented here is a case in which symptomatology suggestive of acute MI occurred with impressive new anterior ST segment elevation in a patient with a history of laryngeal carcinoma. Clinical options in this setting are discussed, including use of thrombolytic agents and acute catheterization.

First clinical experiences with a new angioscopic system for diagnosing peripheral vascular changes

Conventional angiography allows a global view of regional vascular anatomy but precise information can only be deduced indirectly using contrast medium. The use of the three-dimensional picture of angioscopy, however, allows a direct evaluation of the vascular system. In order to extend our experiences with angioscopy, we employed a new micro-cardio-angioscopic system which consists of four components: a CCD color camera (360,000 pixels); a highly flexible optical probe which can be resterilised (1.4-0.6 mm diameter) incorporating 10,600-6,000 glass fibers, with a viewing angle of 140 degrees, 70 degrees, and 50 degrees and a focusing system that allows a distance from 2 mm to infinity; a high power light source and an insertion catheter with inflatable balloon. Using a known technique (intermittent blood-flow blockage and continual rinsing with NaCl solution), 36 cases involving 27 patients were examined before and after desobliteration of the femoral artery. In 88% of the cases it was possible to control the result of the intervention by angioscopy. Smaller intimal lips, the thrombotic wall, and intimal ruptures were clearly visible. Quantification of the stenoses was also successful in 88% of the cases, and in 8 patients the angioscopic findings deviated from the conventional angiogram. In 14% of the cases, angioscopic examination of the recanalisation result showed that thrombolytic therapy was necessary. Angioscopy offers the possibility of qualitative vascular diagnosis. It is a valuable addition to angiography.

Abnormal left ventricular-left atrial posterior wall contour: a new two-dimensional echocardiographic sign in constrictive pericarditis

We measured the angle P formed by the junction of the left ventricular and left atrial posterior walls, and also the distances from the ultrasound transducer to the left ventricular posterior wall and left atrial posterior wall (DV and DA), respectively, in the parasternal long-axis two-dimensional echocardiographic view. We studied 23 normal adults and four patient groups with conditions commonly associated with left atrial dilatation: mitral regurgitation (14), mitral stenosis (16), hypertrophic cardiomyopathy (13), and constrictive pericarditis (7). Statistically significant differences were found between the constrictive pericarditis group and each of the other groups. Angle P was less than 150 degrees in 0 of 23 normal individuals, in 0 of 14 with mitral regurgitation, in 1 of 16 with mitral stenosis, in 0 of 13 with hypertrophic cardiomyopathy, and in five of seven with constrictive pericarditis. DA minus DV exceeded 20 mm in 0 of 23 normal individuals, one of four with mitral regurgitation, in 6 of 16 with mitral stenosis, in 0 of 13 with hypertrophic cardiomyopathy, and in five of seven patients with constrictive pericarditis; We conclude that angle P greater than 150 degrees suggests constrictive pericarditis; DA minus DV greater than 20 mm suggests constrictive pericarditis if mitral stenosis can be excluded.

Echocardiographic detection of an infected superior vena caval thrombus presenting as a right atrial mass

A patient was found to have a large mobile right atrial mass by two-dimensional echocardiography after developing sepsis due to prolonged central hyperalimentation. Contrast echocardiography was helpful in localizing the origin of the mass. A large infected thrombus emanating from the superior vena cava was removed at operation. The discussion includes a review of the literature on the echocardiography of right atrial masses.

Mitral valve prolapse and stroke: echocardiographic evidence for a missing causative link

There is general acceptance of a causal connection between mitral valve prolapse and systemic embolic events. The precise mechanism, however, remains controversial, with current hypotheses favoring the embolization of thrombotic deposits from the abnormal mitral valve. It might be surmised that echocardiography could easily document the presence of such thrombi, but actually, this has never been reported previously. Described herein is a patient with a severe cerebrovascular accident in whom echocardiography clearly demonstrated a mass of high embolic potential attached directly to the prolapsing mitral valve leaflet.

Right atrial thrombus formation following central venous dialysis catheter placement

Silicone rubber central venous dialysis catheters are used to provide vascular access in acute renal failure patients and in chronic dialysis patients in whom conventional vascular access cannot be achieved or maintained. The use of these catheters is not without hazard. The first reported case of right atrial thrombus formation associated with the use of a double lumen silicone rubber central hemodialysis catheter is described. This patient's course points out another potential complication of this type of vascular access and emphasizes the importance of removing such catheters in a timely fashion when they are no longer required for dialysis.

Congenital absence of pericardium: an unusual cause of atypical angina

Congenital defects of the pericardium are unusual. Patients may experience exertional chest pain, cardiac arrhythmias, syncope, sudden death, or incarceration of myocardium, or they may be entirely asymptomatic. We describe the case of a symptomatic pericardial herniation diagnosed by echocardiography and confirmed by cineangiography. Successful repair was accomplished using a polytetrafluoroethylene soft-tissue prosthesis.

Diagnostic precision of echocardiography in mitral valve prolapse

In order to determine the precision with which currently used echocardiographic criteria can be applied for the diagnosis of mitral valve prolapse, three independent observers (A, B, and C) blindly analyzed the separate M-mode and two-dimensional echocardiograms of 50 patients, 27 of whom had previously been identified clinically as having echocardiographic evidence of prolapse. Observer A's intraobserver repeatability for M-mode echocardiography was 92%, Observer B's was 84%, and Observer C's was 90%. For two-dimensional echocardiography, Observer A's intraobserver repeatability was 98%, Observer B's was 80%, and Observer C's was 82%. We believe that the variability in intraobserver repeatability is related to the frequency with which individual observers diagnosed prolapse. The interobserver repeatability for M-mode echocardiography for Observer A versus B was 64%, for Observer A versus C it was 80%, and for Observer B versus C it was 66%. The interobserver repeatability for two-dimensional echocardiography for Observer A versus B was 54%, for Observer A versus C it was 70%, and for Observer B versus C it was 52%. There was no significant difference between the inter- and intraobserver variability of M-mode versus two-dimensional echocardiography. Review of cases in which readings were discrepant revealed that these cases usually had relatively mild changes. Clinicians should be aware of the inherent variability of echocardiographic interpretation when they make a diagnosis of mitral valve prolapse.

The relative merits of pulsus paradoxus and right ventricular diastolic collapse in the early detection of cardiac tamponade: an experimental echocardiographic study

An inspiratory decline in systolic arterial blood pressure exceeding 10 mm Hg has been used clinically to identify hemodynamically significant pericardial effusions. Recently, the echocardiographic sign of right ventricular diastolic collapse (RVDC) has been shown to occur early in the course of cardiac tamponade in association with a hemodynamically important decline in cardiac output. This study was undertaken to compare the relative merits of pulsus paradoxus and the onset of RVDC in the early detection of cardiac tamponade in an unanesthetized canine preparation. We studied six chronically instrumented, conscious dogs with two-dimensional echocardiography during cardiac tamponade induced by continuous infusion of saline into the pericardial space. We recorded intrapericardial pressure, cardiac output (electromagnetic flowmeter), aortic (catheter-tip transducer) and right atrial blood pressures, heart rate, and respiration. None of the dogs had RVDC when the pericardial space was empty, but all dogs showed RVDC during cardiac tamponade. We found that RVDC was strongly related to all of the cardiac parameters evaluated (intrapericardial pressure, cardiac output, aortic blood pressure, heart rate, and stroke volume) and provided information on each that was independent of that provided by pulsus paradoxus. Furthermore, RVDC appeared to be more strongly related to most cardiac parameters than was pulsus paradoxus and to be more sensitive and specific than pulsus paradoxus in detecting changes in intrapericardial pressure early in cardiac tamponade.

Stress echocardiography with transesophageal atrial pacing: preliminary report of a new method for detection of ischemic wall motion abnormalities

We performed two-dimensional echocardiography in 19 patients with significant coronary artery disease and in six normal volunteers at rest and during transesophageal atrial pacing. Technically adequate resting echocardiograms were obtained in 18 of the 19 patients and in all six normal volunteers. In two subjects, atrial capture was not possible, and in one subject, discomfort from the pacing at the beginning of the study precluded its completion. In all subjects (n = 21) who completed the protocol satisfactory two-dimensional echocardiograms were obtained during pacing. Wall motion was normal at rest and during atrial pacing in five normal volunteers. New transient wall motion abnormalities developed in 13 of the 16 patients during pacing. Twelve of the 13 patients had significant coronary lesions in the coronary arteries supplying the abnormal wall segment. Only three of the patients developed significant ST segment depression during pacing. We conclude that stress echocardiography with transesophageal atrial pacing is safe and practical and can be used in patients who cannot perform dynamic exercise, this technique can detect ischemic segmental wall motion abnormalities corresponding to the distribution of coronary arterial obstruction, and the technique provides high-quality echocardiographic images during stress and thus may expand the usefulness of resting two-dimensional echocardiography in patients who have ischemic heart disease.

Digital processing of contrast echocardiograms: a new technique for measuring right ventricular ejection fraction

Imaging of the right ventricle with 2-dimensional echocardiography (2-D echo) is hampered by trabeculation of the right ventricular (RV) endocardial surface and by limited echocardiographic resolution. Determination of RV ejection fraction (EF) is thus often an inconsistent and tedious procedure. The process of digital subtraction contrast echocardiography was developed to maximize echocardiographic definition of the right ventricle and to assess RVEF with minimal operator interaction. Videotaped 2-D echocardiograms recorded during i.v. injection of agitated saline were digitized. Masks were constructed from end-systolic and end-diastolic apical 4-chamber and parasternal RV short-axis images. Masks were subtracted from corresponding images recorded with contrast in the right ventricle; images of the contrast alone were extracted and their areas determined. EF was calculated from raw area measurements and after conversion to volume. Comparison with RVEF measured by first-pass radionuclide angiography yielded the following correlation coefficients: 4-chamber RV area, r = 0.79; parasternal short-axis RV area, r = 0.59; ellipsoid approximation RV volume, r = 0.84; pyramidal RV volume, r = 0.79; and Simpson's rule triangular cylinder RV volume, r = 0.62. Digital subtraction contrast echocardiography is a new method that can be used for semiautomated determination of RVEF. Further studies to assess the clinical values of digital image processing of 2-D echocardiograms to measure RV function appear warranted.

Model for static lifting: relationship of loads on the spine and the knee

An experimental study based on a trigonometric, anthropometric model, was conducted on thirty-five healthy subjects to determine the relationship between knee and back forces during symmetric sagittal plane lifting. Total joint reaction forces for the knee and the back, along with their compressive and shear components, were calculated for each subject, as a function of the knee, back and ankle angles. The shear component was significantly higher in females than in males; the compressive component was significantly higher in males. Strong inverse correlations were found between the back and the knee forces on all subjects. Strong correlations were also found between subject anthropometry and minimum and maximum joint reaction forces. The magnitudes of both back and knee joint reaction forces should be considered in recommending the lift type and position, based upon individual worker anthropometry, and size and weight of the load to be lifted.

Prevalence of mitral prolapse by two dimensional echocardiography in healthy young women

In order to establish the relative prevalence of mitral valve prolapse as diagnosed by two dimensional echocardiography, we studied 100 presumably healthy young women with two dimensional echocardiography and M-mode echocardiography, history, physical examination, electrocardiography, and phonocardiography. Two dimensional echocardiograms were obtained from parasternal, apical, and subcostal acoustic windows. Mitral valve prolapse was defined as extension of leaflet tissue cephalad to the plane of the mitral annulus into the left atrium; note was also made of any valvular thickening, redundancy, or excessive annular motion. One subject had a midsystolic click and late systolic murmur with evidence of mitral prolapse on both M-mode and two dimensional echocardiography. One subject had a midsystolic click with mitral prolapse demonstrated by two dimensional but not on M-mode echocardiography. One subject had a thick mitral valve on echocardiography but no click or murmur. Four subjects had midsystolic clicks without echocardiographic abnormalities. Mild artefactual pansystolic posterior bowing of the mitral valve on the M-mode echocardiogram could be produced in 20 subjects by incorrect transducer position. We conclude that the prevalence of mitral valve prolapse by two dimensional echocardiography is relatively low in presumably healthy young women. Use of two dimensional echocardiography may avoid overdiagnosis of mitral prolapse and identify a smaller group of individuals with true anatomical abnormalities of the mitral valve.

Two-dimensional echocardiography in the diagnosis of left atrial myxoma

We performed M-mode echocardiograms on 11 patients who later had left atrial myxomas removed at operations. Seven of these 11 patients were also examined with two-dimensional echocardiography. M-mode echocardiography showed the characteristic pattern of a left atrial mass entering the mitral orifice during diastole in nine of the 11 patients. M-mode echocardiographic findings were equivocal in two patients because a short tumour stalk prevented significant motion of the tumour. Cross-sectional echocardiography clearly showed a left atrial mass attached by a stalk to the interatrial septum in all seven patients examined, including one patient in whom the tumour was immobile. Three-dimensional measurements of tumour size made from orthogonal cross-sectional echocardiographic planes were within 6 mm of similar measurements made on the excised tumours.

Infected left atrial myxoma with bacteremia simulating infective endocarditis

A 58-year-old man had intermittent fever of eight months' duration following a dental extraction. There were no abnormal cardiac auscultatory findings. Multiple blood cultures yielded Streptococcus mutans. Treatment for infective endocarditis was initiated; however, an echocardiogram suggested the presence of a left atrial myxoma. The diagnosis was confirmed by angiography and the infected tumor was removed successfully. Differentiating features between left atrial myxoma and mitral valve endocarditis may not be obvious clinically, and bacteremia does not preclude atrial myxoma as a diagnostic possibility. We therefore suggest that all cases of infective endocarditis be evaluated by echocardiography to elucidate lesions such as large vegetations or left atrial myxoma, both of which may require urgent operative intervention.

Mitral valve prolapse in the elderly

This study included 40 patients over 60 years of age with echocardiographic findings of mitral valve prolapse (MVP). Most of these patients were unaware of any cardiac disorder until the time of echocardiography. In the majority, the clinical manifestations were benign, and the duration of symptoms variable. Congestive heart failure (CHF) was noted in 10 patients (25 percent) who were unaware of having any cardiac disorders until the onset of their symptoms. In 5 patients (4 with CHF and 1 with endocarditis), surgical replacement of the prolapsed mitral valve was necessary. Endocarditis was present in 4 patients (10 percent), none of whom had been instructed in the prophylactic use of antibiotics. The physician's awareness of mitral valve prolapse in the elderly patient is important, since the disorder may not be as benign in aged patients as in younger ones, and life-threatening complications may occur.

Echocardiography of cardiac valves in pericardial effusion

Nine adult patients with large pericardial effusions (PE) demonstrated echocardiographic motion abnormalites of cardiac valves in systole. In four cases (Group 1), the abnormal findings consisted of prominent systolic anterior movements of the mitral valve resembling those seen in idiopathic hypertrophic subaortic stenosis. In Group 2(five cases), typical mitral valve prolapse patterns with large posterior midsystolic displacements well below the C point were observed. Additional abnormalities in Group 2 included tricuspid valve prolapse patterns (four cases), early systolic movement of the aortic valve toward closure (three cases), midsystolic notching of the pulmonary valve (two cases) and abnormal or attenuated motion of the aortic root in all patients. Marked decrease or resolution of PE resulted in complete disappearance of all the observed abnormalities. These findings appeared to be related to large fluid collections behind the left atrium and abnormal movement of the heart in the pericardial space. In the presence of PE, therefore, the echocardiographic observation of abnormal valve motion may not be clinically significant.

Echocardiographic studies of abnormalities associated with coarctation of the aorta

Echocardiograms were performed in thirty-six patients (aged 4 to 36 years) with proven coarctation of the aorta. Nineteen patients (53%) were found to have marked diastolic eccentricities of their aortic valves (Eccentricity Index greater 1.5), indicating the presence of bicuspid aortic valves. One of these patients also had multilayered aortic root echoes in diastole. Five patients had angiographic proof of their aortic valve morphologies which corroborated the echo findings. Five patients with bicuspid aortic valves showed mitral valve diastolic flutter indicative of aortic regurgitation. Idiopathic hypertrophic subaortic stenosis (IHSS) was suspected in four patients (11%) with abnormal systolic anterior motion of the mitral valve; three of these patients also had asymmetric septal hypertrophy. There was catheterization proof of IHSS in one patient. Two patients (5.6%) demonstrated mitral valve proplapse.