Impact of Vibration on the Levels of Biomarkers: A Systematic Review

Introduction:

The objective of this systematic review is to assess the effect of vibrational force on biomarkers for orthodontic tooth movement.

Methods:

An electronic search was conducted for relevant studies (up to December 31, 2020) on the following databases: Pubmed, Google scholar, Web of Science, Cochrane Library, Wiley Library, and ProQuest Dissertation Abstracts and Thesis database. Hand searching of selected orthodontic journals was also undertaken. The selected studies were assessed for the risk of bias in Cochrane collaboration risk of bias tool. The “traffic plot” and “weighted plot” risk of bias distribution are designed in the RoB 2 tool. The 2 authors extracted the data and analyzed it.

Results:

Six studies fulfilled the inclusion criteria. The risks of biases were high for 4, low and some concern for other 2 studies. The biomarkers, medium, device, frequency and duration of device, as well as other data were extracted. The outcomes of the studies were found to be heterogenous.

Conclusion:

One study showed highly statistically significant levels of IL-1 beta with <.001. Rate of tooth movement was correlated with levels of released biomarkers under the influence of vibrational force in 3 studies, but it was found to be significant only in 1 study. It was further observed that vibration does not have any significant reduction in pain and discomfort.

Identification of the chitinase genes from the diamondback moth, Plutella xylostella

Chitinases have an indispensable function in chitin metabolism and are well characterized in numerous insect species. Although the diamondback moth (DBM) Plutella xylostella, which has a high reproductive potential, short generation time, and characteristic adaptation to adverse environments, has become one of the most serious pests of cruciferous plants worldwide, the information on the chitinases of the moth is presently limited. In the present study, using degenerated polymerase chain reaction (PCR) and rapid amplification of cDNA ends-PCR strategies, four chitinase genes of P. xylostella were cloned, and an exhaustive search was conducted for chitinase-like sequences from the P. xylostella genome and transcriptomic database. Based on the domain analysis of the deduced amino acid sequences and the phylogenetic analysis of the catalytic domain sequences, we identified 15 chitinase genes from P. xylostella. Two of the gut-specific chitinases did not cluster with any of the known phylogenetic groups of chitinases and might be in a new group of the chitinase family. Moreover, in our study, group VIII chitinase was not identified. The structures, classifications and expression patterns of the chitinases of P. xylostella were further delineated, and with this information, further investigations on the functions of chitinase genes in DBM could be facilitated.

First clinical use of a novel neurovascular access and neuroprotection system demonstrates complete absence of emboli by transcranial Doppler during carotid artery stenting

This article focuses on the first use of the MICHI™ Neuroprotection System in a transcervical carotid artery stenting procedure. The patient presented with an asymptomatic, 80% stenosis of the right internal carotid artery extending into the common carotid artery. The lesion was successfully treated with transcervical carotid access and reverse flow embolic protection and the successful placement of a carotid stent followed by balloon post-dilatation. Transcranial Doppler monitoring was performed throughout the procedure and a total of two micro embolic signals were recorded over the 30 minute procedural period. There were no neurologic complications reported during the 30-day follow-up period.

Does higher diastolic augmentation predict clinical benefit from enhanced external counterpulsation?: Data from the International EECP Patient Registry (IEPR)

BACKGROUND

Enhanced external counterpulsation (EECP) has been demonstrated to be an effective treatment for stable angina in patients with coronary disease. The hemodynamic effects of EECP are maximized when the ratio of diastolic to systolic pressure area is in the range of 1.5 to 2.0.

HYPOTHESIS

It is hypothesized that patients undergoing EECP who are able to achieve higher diastolic augmentation (DA) ratios may derive greater clinical benefit. This study examines the relationship between the DA ratio and clinical outcomes in patients undergoing EECP.

METHODS

We analyzed demographic, noninvasive hemodynamic, and clinical outcome data on 1,004 patients enrolled in the International EECP Patient Registry (IEPR) for treatment of chronic angina between January 1998 and August 1999. Blood pressure waveforms were recorded from finger plethysmography. Six-month clinical outcomes were obtained by telephone interview.

RESULTS

At the end of EECP treatment, 370 (37%) patients had a higher DA ratio (defined as > or = 1.5) and 634 (63%) had a lower DA ratio (defined as < 1.5). Factors associated with a lower DA ratio included age > or =65 years (p <0.001), female gender (p < 0.001), left ventricular ejection fraction < 35% (p < 0.05), hypertension (p < 0.01), prior coronary bypass surgery (p < 0.01), noncardiac vascular disease (p < 0.001), multivessel disease (p < 0.01), congestive heart failure (p < 0.01), current smoking (p < 0.01), unsuitability for further revascularization (p < 0.001), and higher baseline angina class (p < 0.001). There were no significant differences regarding diabetes mellitus, prior coronary angioplasty, prior myocardial infarction, or antianginal medication use between patients with higher or lower DA ratios. Based on a multiple logistic regression model, independent predictors of a DA ratio < 1.5 at the end of EECP included current smoking (odds ratio 3.3; 95% confidence intervals 2.0-5.4); multivessel disease (1.7; 1.3-2.3); female gender (2.2; 1.7-3.0); no prior EECP (1.9; 1.1-3.3); noncardiac vascular disease (2.3; 1.7-2.9); age > or = 65 years (1.7; 1.4-2.2), and patients not suitable for revascularization (1.6; 1.2-2.0). By the end of therapy, there were no significant differences in myocardial infarction, revascularization rates, or nitroglycerin use with respect to higher DA ratios. At 6-month follow-up, patients with higher DA had a trend toward a greater reduction in angina class compared with those with lower DA (p = 0.069). There was a significantly higher rate of unstable angina and congestive heart failure in the group not achieving higher augmentation (p < 0.05).

CONCLUSIONS

Patients who are younger, male, nonsmoking, and without multivessel coronary or noncardiac vascular disease are most likely to have higher DA with EECP. Patients with higher DA tended to have a greater reduction in angina class at 6-month follow-up compared with those with lower DA ratios. There is evidence that higher DA ratios are associated with improved short- or long-term clinical outcomes, suggesting that clinical benefit from EECP is associated with the magnitude of DA.

The StarClose® vascular closure system: Interventional results from the CLIP study

BACKGROUND

The StarClose Vascular Closure System is a femoral access site closure technology that uses a flexible nitinol clip to complete a circumferential, extravascular arteriotomy close. The Clip CLosure In Percutaneous Procedures study was initiated to study the safety and efficacy of the StarClose device in subjects undergoing diagnostic and interventional catheterization procedures.

METHODS

A total of 17 U.S. sites enrolled 596 subjects, with 483 subjects randomized at a 2:1 ratio to receive StarClose or standard compression of the arteriotomy after the percutaneous procedure. The study included roll-in (n = 113), diagnostic (n = 208), and interventional (n = 275) arms with a primary safety endpoint of major vascular complications through 30 days and a primary efficacy endpoint of postprocedure time to hemostasis.

RESULTS

The results of the diagnostic StarClose cohort have been reported separately. Results for the interventional arm revealed major vascular complications occurring in 1.1% of StarClose subjects (2/184) and 1.1% in manual compression subjects (1/91; P = 1.00). No infections were seen in either cohort. Minor complications in the StarClose interventional group occurred at a rate of 4.3% (8/184) and with compression at 9.9% (9/91; P = 0.107). Pseudoaneurysm or arteriovenous fistula was not seen with StarClose. With StarClose, procedural success was 100% (136/136) for the diagnostic group and 98.9% (181/183) in the interventional group. Device success for the treatment group was 86.8%. In the interventional cohort, 87.3% (158/181) of StarClose subjects reported a pain scale of 0-3 compared with 93.3% (84/90) in the compression group, which was not statistically different.

CONCLUSIONS

The clinical results of this study demonstrate that the StarClose Vascular Closure System is noninferior to manual compression with respect to the primary safety endpoint of major vascular events in subjects who undergo percutaneous interventional procedures. StarClose significantly reduced time to hemostasis, ambulation, and dischargeability when compared with compression.

The safety and efficacy of the StarClose® vascular closure system: The ultrasound substudy of the CLIP study

BACKGROUND

The StarClose Vascular Closure System (Abbott Vascular, Redwood City, CA) features a nitinol clip that is designed to achieve closure of the femoral arteriotomy access site. The CLIP Study was performed to assess the safety and efficacy of StarClose when compared with standard manual compression following 5-6 French diagnostic or interventional percutaneous procedures. A substudy of this trial was designed to assess the utility of duplex ultrasonography to assess patency of the femoral artery and to determine access site complications (pseudoaneurysm, arteriovenous fistula, hematoma, deep vein thrombosis) in a multicenter prospective trial. This is the report of the duplex ultrasound (DUS) substudy of the CLIP trial.

METHODS

A total of 17 U.S. sites enrolled 596 subjects with 483 subjects randomized at a 2:1 ratio to receive StarClose or manual compression of the arteriotomy after a percutaneous procedure. The study included roll-in (n = 113), diagnostic (n = 208), and interventional (n = 275) arms with a primary safety endpoint of major vascular complications through 30 days and a primary efficacy endpoint of postprocedure time to hemostasis. A substudy of the CLIP interventional arm evaluated DUS images of the closure site at five study sites, targeting 100 subjects at day 30 following hemostasis. The DUS protocol was devised and implemented by an independent vascular ultrasound core laboratory with extensive experience in vascular device trials. DUS inguinal region from 6 cm proximal to 6 cm distal to the arteriotomy puncture was performed. A qualitative examination was performed to determine the presence of iatrogenic vascular injuries: hematoma, pseudoaneurysm (PSA), arteriovenous fistula (AVF), and arterial/venous thrombosis or stenosis using 2-dimensional gray scale, color, and focused Doppler images.

RESULTS

DUS of 96 subjects randomized to StarClose (n = 71) and compression (n = 25) were performed and evaluated. There was no evidence of hematoma, PSA, or AVF observed in the StarClose group. No StarClose subjects in the substudy had a PSA or AVF. All patients in the substudy demonstrated patency of the access site artery and vein without thrombosis or stenosis. Finally, in the entire study cohort, no clinically-driven DUS studies demonstrated iatrogenic vascular injury or vessel thrombosis in the StarClose treated patients.

CONCLUSION

DUS, a safe and reliable method for determining the safety and efficacy of access site closure devices, is a reliable, safe, inexpensive and accurate method of assessing vascular access site complications in multicenter trials. In this substudy of the CLIP study, DUS found no statistical difference in access site complications between the StarClose and manual compression groups. Both groups maintained vessel patency without stenosis, thrombosis, hematoma, pseudoaneurysm, or AV fistula.

Mean free paths for inelastic electron scattering in silicon and poly(styrene) nanospheres

The mean free paths for inelastic electron scattering, lambda(in), in silicon [Si] and poly(styrene) [PS] have been measured using off-axis electron holography in a field-emission transmission electron microscope (FEG TEM). The holographic imaging method determines both quantitative wave phase information as well as elastic energy-filtered wave amplitude information. Using the energy-filtered amplitude data, two-dimensional t/lambda(in) images are reconstructed. The present work uses spherical nanoparticles as samples, so the sample thickness at any point in a two-dimensional image can be calculated knowing the center and radius of the projected nanosphere. The thickness contribution to t/lambda(in) is removed to obtain quantitative lambda(in) values. This work finds values of lambda(i)Si = 53.8 +/- 5.5 and 88.6 +/- 6.9 nm, and lambda(PS) = 78.1 +/- 3.4 and 113.0 +/- 5.9 nm for 120 and 200 keV incident electron energies, respectively.

Tamoxifen is an acute, estrogen-like, coronary vasodilator of porcine coronary arteries in vitro

Tamoxifen is a mixed estrogen antagonist and agonist. Observational data from breast cancer studies associate tamoxifen use with lesser rates of myocardial infarction. The authors sought to determine the acute vasoactive properties of tamoxifen compared with estradiol. Isolated coronary ring segments from female pigs were studied in organ baths. KCl-precontracted ring segments were exposed to increasing doses of both tamoxifen and estradiol (log-9-log-5 M ). Ring segments were also exposed to tamoxifen and estradiol in the presence of inhibitors of nitric oxide, glybenclamide, the hormone receptor antagonists ICI 182,780 and flutamide, and after de-endothelialization. Tamoxifen caused acute dilation of coronary arteries but less than estradiol. Tamoxifen-and estradiol-induced acute vasodilation was not nitric oxide- or endothelium-dependent, but was adenosine triphosphate-sensitive potassium channel-dependent. Tamoxifen-induced vasorelaxation was inhibited by antagonism of the classic estrogen receptor and antagonism of the androgen receptor with flutamide, whereas estrogen-induced vasorelaxation was inhibited partially by classic estrogen receptor antagonism but not by androgen receptor antagonism. Tamoxifen attenuated both the sensitivity of vasoconstriction to endothelin-1 and the maximal response. Tamoxifen and estradiol are both acute coronary vasodilators, with similar mechanisms of action. Tamoxifen also attenuates coronary vasoconstriction. Such properties may account for some of the observed cardiovascular clinical benefits seen in observational studies of tamoxifen use.

Fractional flow reserve compared with intravascular ultrasound guidance for optimizing stent deployment

BACKGROUND

Determination of fractional flow reserve (FFR) has been proposed as a means to assess stent deployment. In this prospective, multicenter trial, we evaluate the use of FFR to optimize stenting by comparing it with standard intravascular ultrasound (IVUS) criteria.

METHODS AND RESULTS

Eighty-four stable patients with isolated coronary lesions underwent coronary stent deployment starting at 10 atm and increased serially by 2 atm until the FFR was >/=0.94 or 16 atm was achieved. IVUS was then performed. FFR was measured with a coronary pressure wire with intracoronary adenosine to induce hyperemia. The diagnostic characteristics of an FFR <0.94 to predict suboptimal stent expansion by IVUS, defined in both absolute and relative terms, were calculated. Over a range of IVUS criteria, the highest sensitivity, specificity, and predictive accuracy of FFR were 80%, 30%, and 42%, respectively. Receiver operator characteristic analysis defined an optimal FFR cut point at >/=0.96; at this threshold, the sensitivity, specificity, and predictive accuracy of FFR were 75%, 58%, and 62%, respectively (P=0.03 for comparison of predictive accuracy, P=0.01 for concordance between FFR and IVUS). The negative predictive value was 88%. Significantly better diagnostic performance was achieved in a subgroup that received higher doses (>30 microgram) of intracoronary adenosine during pressure measurements, suggesting that FFR might be overestimated in the other group.

CONCLUSIONS

A fractional flow reserve <0.96, measured after stent deployment, predicts a suboptimal result based on validated intravascular ultrasound criteria; however, an FFR >/=0.96 does not reliably predict an optimal stent result. Higher doses of intracoronary adenosine than previously used to measure FFR improve these results.

The use of intra-aortic balloon counterpulsation in patients with cardiogenic shock complicating acute myocardial infarction: data from the National Registry of Myocardial Infarction 2

BACKGROUND

Cardiogenic shock complicating acute myocardial infarction (AMI) remains the leading cause of death in patients hospitalized with AMI. Although several studies have demonstrated the importance of establishing and maintaining a patent infarct-related artery, it remains unclear as to whether intra-aortic balloon counterpulsation (IABP) provides incremental benefit to reperfusion therapy. The purpose of this study was to determine whether IABP use is associated with lower in-hospital mortality rates in patients with AMI complicated by cardiogenic shock in a large AMI registry.

METHODS

We evaluated patients participating in the National Registry of Myocardial Infarction 2 who had cardiogenic shock at initial examination or in whom cardiogenic shock developed during hospitalization (n = 23,180).

RESULTS

The mean age of patients in the study was 72 years, 54% were men, and the majority were white. The overall mortality rate in all patients who had cardiogenic shock or in whom cardiogenic shock developed was 70%. IABP was used in 7268 (31%) patients. IABP use was associated with a significant reduction in mortality rates in patients who received thrombolytic therapy (67% vs 49%) but was not associated with any benefit in patients treated with primary angioplasty (45% vs 47%). In a multivariate model, the use of IABP in conjunction with thrombolytic therapy decreased the odds of death by 18% (odds ratio, 0.82; 95% confidence interval, 0.72 to 0.93).

CONCLUSIONS

Patients with AMI complicated by cardiogenic shock may have substantial benefit from IABP when used in combination with thrombolytic therapy.

Comparative effects of ACE inhibitors and an angiotensin receptor blocker on atherosclerosis and vascular function

BACKGROUND

Both angiotensin-converting enzyme inhibitors (ACE-I(s)) and angiotensin receptor blockers (ARB(s)) provide vascular protection. This study was designed to compare ACE-I(s) with widely differing tissue affinity (captopril and quinapril) and an ARB (losartan) on vascular protection against the adverse effects of high cholesterol.

METHODS AND RESULTS

Forty-two New Zealand rabbits on a 0.5% cholesterol diet were randomized into control, captopril (10 mg/kg/d), quinapril (0.3 mg/kg/d), and losartan (8 mg/kg/d) groups for 14 weeks. Captopril, quinapril, and losartan significantly attenuated aortic lipid lesions (P=0.001). Captopril and quinapril were more effective than losartan in preserving vascular relaxation.

CONCLUSIONS

Captopril, quinapril, and losartan had similar protective effects against atherogenesis. Captopril and quinapril were more effective than losartan in preserving vascular function. Increased bradykinin by ACE inhibition may be responsible for this improved vascular endothelial function.

Development of a molecular probe to baboon interleukin-10 mRNA for in situ hybridization during experimental schistosomiasis

A nucleic acid probe complementary to baboon interleukin 10 (IL-10) mRNA was developed for in situ hybridization. Highly conserved IL-10 protein sequences from several mammals were aligned to design oligonucleotide primers flanking a 270-bp sequence of the target cDNA. RNA was isolated from stimulated peripheral blood mononuclear cells (PBMC). IL-10 cDNA was reverse-transcribed from the total PBMC RNA and amplified with the polymerase chain reaction (PCR). Cloning and sequencing of the PCR product confirmed it to be of baboon IL-10 origin, with 97.8% identity to human and 100% identity to macaque mRNA sequences. The baboon IL-10 DNA probe hybridized in Southern blots to a 7.9-Kbp or 8.6-Kbp band after digestion of genomic baboon DNA with Bam H1 or Eco R1, respectively. Preliminary results with an antisense riboprobe derived from this sequence showed the presence of IL-10 mRNA in sections of granulomatous tissues.

Use of fractional myocardial flow reserve to assess the functional significance of intermediate coronary stenoses

The goal of the present study was to compare the use of pressure-derived myocardial fractional flow reserve for detecting ischemia with nuclear stress imaging in patients undergoing stent placement for intermediate coronary lesions. We demonstrated that myocardial fractional flow reserve detects ischemia in intermediate coronary lesions accurately when compared with nuclear stress imaging.

Intracoronary measurement of pulsus alternans

Pulsus alternans is typically found in patients with left ventricular systolic dysfunction. We describe a woman with biventricular systolic dysfunction and pulsus alternans in the right ventricle, pulmonary artery, and aorta. Coronary angiography revealed an intermediate stenosis in the proximal left anterior descending (LAD) coronary artery. Pulsus alternans was demonstrated in the mid LAD using a 0.014" guidewire-mounted pressure sensor. An abnormal fractional flow reserve was measured in the LAD. Cathet. Cardiovasc. Intervent. 51:335-338, 2000.

Anti-SSA/Ro and anti-SSB/La autoantibodies bind the surface of apoptotic fetal cardiocytes and promote secretion of TNF-alpha by macrophages

Despite the near universal association of congenital heart block and maternal Abs to SSA/Ro and SSB/La, the intracellular location of these Ags has made it difficult to substantiate their involvement in pathogenicity. To define whether components of the SSA/Ro-SSB/La complex, which translocate during apoptosis, are indeed accessible to extracellular Abs, two approaches were taken: immunoprecipitation of surface biotinylated proteins and scanning electron microscopy. Human fetal cardiocytes from 16-24-wk abortuses were cultured and incubated with staurosporine to induce apoptosis. Surface biotinylated 48-kDa SSB/La was reproducibly immunoprecipitated from apoptotic, but not nonapoptotic cardiocytes. Surface expression of SSA/Ro and SSB/La was further substantiated by scanning electron microscopy. Gold particles (following incubation with gold-labeled sera containing various specificities of anti-SSA/Ro-SSB/La Abs and murine mAb to SSB/La and 60-kDa SSA/Ro) were consistently observed on early and late apoptotic cardiocytes. No particles were seen after incubation with control antisera. To evaluate whether opsonized apoptotic cardiocytes promote inflammation, cells were cocultured with macrophages. Compared with nonapoptotic cardiocytes or apoptotic cardiocytes incubated with normal sera, apoptotic cardiocytes preincubated with affinity-purified Abs to SSB/La, 52-kDa SSA/Ro, or 60-kDa SSA/Ro increased the secretion of TNF-alpha from cocultured macrophages. In summary, apoptosis results in surface accessibility of all SSA/Ro-SSB/La Ags for recognition by circulating maternal Abs. It is speculated that in vivo such opsonized apoptotic cardiocytes promote an inflammatory response by resident macrophages with damage to surrounding conducting tissue.

Serial laparoscopic biopsies of liver and spleen from Schistosoma-infected baboons (Papio spp.)

PURPOSE

To obtain large, serial biopsy samples from the liver and spleen by using laparoscopy. Large samples were needed for measurement of inflammatory mediators during various stages of schistosomiasis.

METHODS

Each of the seven female baboons (Papio sp.) underwent as many as three laparoscopies, for a total of 19 laparoscopic procedures. This process permitted sampling of the liver, spleen, and mesenteric lymph nodes before and at 6 and 9 weeks after infection with Schistosoma mansoni. All surgery was performed through three trocar sites. Postoperative care included preemptive analgesia. After surgery, we monitored the animals' appetite and measured the core body temperature and activity by using implanted radiofrequency transmitters.

RESULTS

We obtained samples of the liver and splenic biopsies during all 19 laparoscopic procedures. The mean weight of the liver biopsies was 3.7 g and that of the spleen samples was 5.3 g. We encountered small adhesions during 5 of the 12 reoperations. Eating and activity rapidly returned after surgery.

CONCLUSIONS

Laparoscopy permitted collection of large, serial biopsies with apparently limited stress to the animals. Laparoscopy can be used for biopsies in studies to characterize disease response, confirm normal organ histology prior to drug toxicity studies, determine target-organ drug concentrations in pharmacokinetic studies, and measure drug residues. This refinement likely will reduce required animal numbers by decreasing the effect of surgery compared to that of the experimental conditions, enhance animal well-being, and permit repeated measurements in an animal that serves as its own control.

Acute occlusion of left internal mammary artery graft during dual-chamber pacemaker implantation

A patient who had undergone bypass surgery 5 yr earlier, including left internal mammary artery (LIMA) grafting to the left anterior descending artery, underwent transvenous dual-chamber permanent pacemaker implantation for persistent advanced atrioventricular block. Intraoperative LIMA graft obstruction occurred, resulting in anterior myocardial infarction that was treated successfully by primary percutaneous transluminal coronary angioplasty and stenting. This is the first report of the occurrence of this complication during pacemaker implantation.

Teleconferencing with dynamic medical images

Dynamic images, a sequence of static images displayed in rapid succession and perceived as a continuous motion by the human eye, are widely used in medicine. One of the primary objectives of telemedicine is the transmission of such images to a distant location to manage clinical problems remotely. A broad variety of methods is available to acquire, store, transmit, and display these images. However, the context of the clinical problem determines which of these methods can be deployed in a telemedicine solution. This paper discusses the advantages and disadvantages of the different technologies and presents an example of a teleconferencing system for interventional cardiology. This system acquires cardiac angiography and intravascular ultrasound images and transmits them over an existing Internet connection to a distant location. It is specifically optimized for clinical conferencing, where time is limited for each case presentation during the conference, compared to the relatively long time available for the conference preparation. The system takes advantage of this characteristic by transmitting the images well in advance of the clinical conference and displaying them synchronously in both locations during the conference. This allows for the preservation of the original image quality.

Comparative effects of pretreatment with captopril and losartan on cardiovascular protection in a rat model of ischemia-reperfusion

OBJECTIVES

We sought to assess the comparative effects of pretreatment with captopril and losartan on myocardial infarct size and arrhythmias in a rat model of ischemia-reperfusion.

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) inhibit the renin-angiotensin system in different ways. However, the comparative effects of pretreatment with ACE inhibitors or ARBs on acute myocardial infarct size and arrhythmias are unknown.

METHODS

We randomly assigned 117 female Sprague-Dawley rats into three groups: group N was the normal control; group C was given 40 mg/kg body weight per day of captopril in drinking water; and group L was given 40 mg/kg per day of losartan in drinking water. After 10 weeks of pretreatment, 25 rats in each group were subjected to 17 min of left anterior descending coronary artery occlusion and 2 h of reperfusion with hemodynamic and electrocardiographic monitoring. Fourteen rats in each group had blood samples drawn and aortic rings removed to study vascular reactivity.

RESULTS

Mortality during ischemia and reperfusion was lower in combined groups L and C than in group N (4.2% vs. 19.2%, p = 0.042). Rats treated with losartan had significantly higher levels of angiotensin II in their plasma. Hemodynamic variables were not significantly different among the three groups. The thresholds of ventricular fibrillation (VF) before occlusion and after reperfusion were significantly higher in groups L and C than in group N (1.99 +/- 0.24 and 1.93 +/- 0.27 vs. 1.23 + 0.17 mA, p = 0.04; 2.13 +/- 0.25 and 1.78 +/- 0.22 vs. 0.95 +/- 0.11 mA, p = 0.001). The average episodes of ventricular tachycardia (VT) and VF per rat were significantly less in groups L and C than in group N (0.96 +/- 0.2 and 1.2 +/- 0.3 vs. 2.8 + 0.4 mA, p < 0.001). Myocardial infarct size was significantly smaller in groups L and C than in group N (34 +/- 3% and 35 +/- 3% vs. 44 +/- 3%, p = 0.031, 0.043). Endothelium-dependent vasorelaxation induced by a calcium ionophore (A23187) was increased in both groups but was only statistically significant in group C (p = 0.020).

CONCLUSIONS

Losartan and captopril have similar cardiovascular protective effects in a rat model of ischemia-reperfusion. They increased the threshold of VF, decreased mortality and decreased episodes of VT and VF, as well as decreased myocardial infarct size.

Echocardiography in patients with suspected endocarditis: a cost-effectiveness analysis

PURPOSE

We sought to determine the appropriate use of echocardiography for patients with suspected endocarditis.

PATIENTS AND METHODS

We constructed a decision tree and Markov model using published data to simulate the outcomes and costs of care for patients with suspected endocarditis.

RESULTS

Transesophageal imaging was optimal for patients who had a prior probability of endocarditis that is observed commonly in clinical practice (4% to 60%). In our base-case analysis (a 45-year-old man with a prior probability of endocarditis of 20%), use of transesophageal imaging improved quality-adjusted life expectancy (QALYs) by 9 days and reduced costs by $18 per person compared with the use of transthoracic echocardiography. Sequential test strategies that reserved the use of transesophageal echocardiography for patients who had an inadequate transthoracic study provided similar QALYs compared with the use of transesophageal echocardiography alone, but cost $230 to $250 more. For patients with prior probabilities of endocarditis greater than 60%, the optimal strategy is to treat for endocarditis without reliance on echocardiography for diagnosis. Patients with a prior probability of less than 2% should receive treatment for bacteremia without imaging. Transthoracic imaging was optimal for only a narrow range of prior probabilities (2% or 3%) of endocarditis.

CONCLUSION

The appropriate use of echocardiography depends on the prior probability of endocarditis. For patients whose prior probability of endocarditis is 4% to 60%, initial use of transesophageal echocardiography provides the greatest quality-adjusted survival at a cost that is within the range for commonly accepted health interventions.

Effects of L-arginine on atherogenesis and endothelial dysfunction due to secondhand smoke

Secondhand smoke (SHS) and hypercholesterolemia increase cardiovascular risk. We hypothesized that L-arginine, the precursor of nitric oxide (NO), might protect against atherogenesis and endothelial dysfunction caused by SHS. The effects of L-arginine supplementation (2.25% solution ad libitum) and SHS (smoking chambers for 10 weeks) were examined in 32 hypercholesterolemic rabbits. Eight normal rabbits served as controls. Acetylcholine- and nitroglycerin-induced vasorelaxation was assessed in aortic rings precontracted with norepinephrine. Hypercholesterolemia increased intimal lesion area (P=0.012), reduced endothelium-dependent relaxation (P=0.009), and reduced basal (P=0.005) and stimulated (P<0.0005) production of NOs. SHS increased intimal lesion area (P=0. 01) norepinephrine-induced contraction (P=0.001) and reduced endothelium-dependent relaxation (P=0.02). SHS-induced increase in norepinephrine contraction was abolished by the inhibition of NO synthase and removal of endothelium. L-Arginine improved endothelium-dependent relaxation (P=0.001) and attenuated SHS-induced endothelial dysfunction (P=0.007) and atherogenesis (P=0. 001). Basal production of nitrogen oxides correlated inversely with intimal lesion area (r=-0.66; P<0.0005) and stimulated production of NOs correlated with endothelium-dependent relaxation (r=-0.66; P<0. 001). SHS causes endothelial dysfunction and increased adrenergic responsiveness and atherogenesis in hypercholesterolemic rabbits. Chronic dietary supplementation with the NO precursor L-arginine mitigates these effects. The adverse vascular consequences of SHS appear to be mediated via deleterious effects on endothelial function.

The multicenter study of enhanced external counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes

OBJECTIVES

The purpose of this study was to assess safety and efficacy of enhanced external counterpulsation (EECP).

BACKGROUND

Case series have shown that EECP can improve exercise tolerance, symptoms and myocardial perfusion in stable angina pectoris.

METHODS

A multicenter, prospective, randomized, blinded, controlled trial was conducted in seven university hospitals in 139 outpatients with angina, documented coronary artery disease (CAD) and positive exercise treadmill test. Patients were given 35 h of active counterpulsation (active CP) or inactive counterpulsation (inactive CP) over a four- to seven-week period. Outcome measures were exercise duration and time to > or =1-mm ST-segment depression, average daily anginal attack count and nitroglycerin usage.

RESULTS

Exercise duration increased in both groups, but the between-group difference was not significant (p > 0.3). Time to > or =1-mm ST-segment depression increased significantly from baseline in active CP compared with inactive CP (p = 0.01). More active-CP patients saw a decrease and fewer experienced an increase in angina episodes as compared with inactive-CP patients (p < 0.05). Nitroglycerin usage decreased in active CP but did not change in the inactive-CP group. The between-group difference was not significant (p > 0.7).

CONCLUSIONS

Enhanced external counterpulsation reduces angina and extends time to exercise-induced ischemia in patients with symptomatic CAD. Treatment was relatively well tolerated and free of limiting side effects in most patients.

Coronary vasodilator effects of BNP: mechanisms of action in coronary conductance and resistance arteries

Brain natriuretic peptide (BNP), a hormone secreted predominantly in ventricular myocytes, may influence coronary vascular tone. We studied the coronary vasodilatory response to BNP under physiological conditions and after preconstriction with endothelin-1 (ET-1) in anesthetized pigs. Average peak-flow velocity (APV) was measured using intracoronary Doppler, and cross-sectional area (CSA) was measured using intravascular ultrasound. Coronary blood flow (CBF) was calculated. Intracoronary BNP induced dose-dependent increases in CSA, APV, and CBF similar in magnitude to those induced by nitroglycerin (NTG). The magnitude of BNP-induced vasodilation was accentuated after preconstriction with ET-1. Pretreatment with either the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester or the cyclooxygenase inhibitor indomethacin attenuated the coronary vasodilator effect of BNP in resistance arteries without influencing epicardial vasodilation. Pretreatment with the ATP-sensitive potassium-channel blocker glibenclamide enhanced epicardial vasodilation in response to BNP. We conclude that BNP exerts coronary vasodilator effects, predominantly in epicardial conductance vessels. An accentuated vasodilatory response to BNP occurs in ET-1-preconstricted arteries. BNP-induced vasodilation in coronary resistance arteries may be partially mediated via nitric oxide and/or prostaglandin release.

Should the electrocardiogram be used to guide therapy for patients with left bundle-branch block and suspected myocardial infarction?

CONTEXT

Recently, an algorithm based on the electrocardiogram (ECG) was reported to predict myocardial infarction (MI) in patients with left bundle-branch block (LBBB), but the clinical impact of this testing strategy is unknown.

OBJECTIVE

To determine the diagnostic test characteristics and clinical utility of this ECG algorithm for patients with suspected MI.

DESIGN

Retrospective cohort study to which an algorithm was applied, followed by decision analysis regarding thrombolysis made with or without the algorithm.

SETTING

University emergency department, 1994 through 1997.

PATIENTS

Eighty-three patients with LBBB who presented 103 times with symptoms suggestive of MI.

MAIN OUTCOME MEASURES

Myocardial infarction determined by serial cardiac enzyme analyses and stroke-free survival.

RESULTS

Of 9 ECG findings assessed, none effectively distinguished the 30% of patients with MI from those with other diagnoses. The ECG algorithm indicated positive findings in only 3% of presentations and had a sensitivity of 10% (95% confidence interval, 2%-26%). The decision analysis showed that among 1000 patients with LBBB and chest pain, 929 would survive without major stroke if all received thrombolysis compared with 918 if the ECG algorithm was used as a screening test.

CONCLUSIONS

The ECG is a poor predictor of MI in a community-based cohort of patients with LBBB and acute cardiopulmonary symptoms. Acute thrombolytic therapy should be considered for all patients with LBBB who have symptoms consistent with MI.

Isolated inferior rectus palsy caused by a metastasis to the oculomotor nucleus

PURPOSE

To report a case of isolated inferior rectus palsy secondary to a metastasis to the oculomotor nucleus.

METHODS

Case report. A 41-year-old woman with a history of breast cancer presented with acute onset of left hypotropia and exotropia.

RESULTS

Forced generation testing confirmed weakness of the right inferior rectus muscle that was not reversed by intravenous edrophonium infusion. Magnetic resonance imaging disclosed numerous metastatic lesions to the cerebral hemispheres and brainstem. One lesion in the right midbrain was adjacent to the cerebral aqueduct in the right oculomotor nucleus.

CONCLUSION

Metastasis to the oculomotor nucleus is a rare cause of isolated inferior rectus palsy; however, this entity should be considered in the differential diagnosis of an isolated inferior rectus palsy because of the life-threatening consequences of a brainstem lesion.

In-utero and neonatal exposure to secondhand smoke causes vascular dysfunction in newborn rats

OBJECTIVES

We sought to determine the effects of secondhand smoke (SHS) exposure on vascular reactivity in newborn and infant rats.

BACKGROUND

Secondhand smoke exposure increases cardiovascular risk. Secondhand smoke-induced endothelial dysfunction has been demonstrated in older teenagers and young adults. We have previously shown in adult rabbits that SHS induces atherogenesis and endothelial dysfunction. The effects of SHS on vascular function in the offspring of SHS-exposed mothers and in infants are unknown.

METHODS

In this study the effects of in-utero (21 days) and neonatal (28 days) exposure to SHS were examined in 80 rats, 4 weeks of age, in a 2-by-2 design study. Rats were exposed to sidestream smoke in smoking chambers. Aortic rings were excised and isometric force responses to phenylephrine, acetylcholine, A23187 and nitroglycerin were studied in organ baths.

RESULTS

Neonatal SHS exposure reduced animal weight (p=0.009). In-utero exposure increased the sensitivity (decreased the EC50) of aortic rings to phenylephrine (p < 0.0005), as did neonatal exposure (p=0.01). Maximal contraction to phenylephrine was reduced by in-utero exposure (p=0.04). In-utero SHS exposure reduced maximal endothelium-dependent relaxation to acetylcholine (p=0.04) and increased the EC50 (p=0.05), suggesting impaired sensitivity to acetylcholine. In-utero exposure decreased the sensitivity (increased the EC50) to the endothelium-independent vasodilator nitroglycerin (p=0.003).

CONCLUSIONS

Secondhand smoke has detrimental effects on vascular smooth muscle function in the newborn.

12-lead ST-segment monitoring vs single-lead maximum ST-segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes

BACKGROUND: 12-lead ECG monitoring of the ST segment is more sensitive than patients' symptoms for detecting ischemia after thrombolytic therapy or catheter-based interventions, but it is unclear whether monitoring of the single lead showing maximum ST deviation would be as efficacious. OBJECTIVE: To determine whether monitoring all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes. METHODS: Continuous 12-lead ST segment monitoring was performed in 422 patients from the onset of myocardial infarction or during balloon inflation in catheter-based interventions until the patient's discharge from the cardiac care unit. Computer-assisted techniques were used to determine (1) which lead showed the maximum ST deviation at the onset of myocardial infarction or during balloon inflation and (2) what proportion of later ischemic events were associated with ST deviation in this lead. RESULTS: The lead with the maximum ST deviation could be determined in 312 patients (74%). The remaining 110 (26%) had non-Q wave infarction without ST deviation or no ST changes during balloon inflation. During 18,394 hours of 12-lead ST monitoring, 118 (28%) of the 312 patients had a total of 463 ischemic events, 80% of which were silent. Of 377 ischemic events in which a maximum ST lead was detected, 159 (42%) did not show ST deviation in this lead (sensitivity, 58%; 95% CI, 53%-63%). Routine monitoring of leads V1 and II showed ST deviation in only 152 of the 463 events (sensitivity, 33%; 95% CI, 29%-37%). CONCLUSIONS: Monitoring of all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.

12-lead ST-segment monitoring vs single-lead maximum ST-segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes

BACKGROUND

12-lead ECG monitoring of the ST segment is more sensitive than patients' symptoms for detecting ischemia after thrombolytic therapy or catheter-based interventions, but it is unclear whether monitoring of the single lead showing maximum ST deviation would be as efficacious.

OBJECTIVE

To determine whether monitoring all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.

METHODS

Continuous 12-lead ST segment monitoring was performed in 422 patients from the onset of myocardial infarction or during balloon inflation in catheter-based interventions until the patient's discharge from the cardiac care unit. Computer-assisted techniques were used to determine (1) which lead showed the maximum ST deviation at the onset of myocardial infarction or during balloon inflation and (2) what proportion of later ischemic events were associated with ST deviation in this lead.

RESULTS

The lead with the maximum ST deviation could be determined in 312 patients (74%). The remaining 110 (26%) had non-Q wave infarction without ST deviation or no ST changes during balloon inflation. During 18,394 hours of 12-lead ST monitoring, 118 (28%) of the 312 patients had a total of 463 ischemic events, 80% of which were silent. Of 377 ischemic events in which a maximum ST lead was detected, 159 (42%) did not show ST deviation in this lead (sensitivity, 58%; 95% CI, 53%-63%). Routine monitoring of leads V1 and II showed ST deviation in only 152 of the 463 events (sensitivity, 33%; 95% CI, 29%-37%).

CONCLUSIONS

Monitoring of all 12 ECG leads for changes in the ST segment is necessary to detect ongoing ischemia in patients with unstable coronary syndromes.

Antioxidant diet preserves endothelium-dependent vasodilatation in resistance arteries of hypercholesterolemic rabbits exposed to environmental tobacco smoke

Environmental tobacco smoke (ETS) has been shown to impair endothelium-dependent vasodilation in vitro. This study was performed to investigate the effect of ETS on acetylcholine (ACh)-mediated blood pressure changes in vivo. Seventeen New Zealand White rabbits were fed a cholesterol diet (0.3%) for 13 weeks. Ten animals were exposed to ETS for 6 h/day, and seven animals were not exposed to ETS (non-ETS). Four of the ETS and three of the non-ETS-exposed rabbits received an antioxidant vitamin diet before and during their cholesterol diet for 21 weeks. Six rabbits served as healthy controls. To determine endothelium-dependent and independent blood pressure (BP) responses, BP was measured through a Tygon catheter, inserted into the right carotid artery at baseline and after each of three incremental intravenous doses of norepinephrine (NE; 1, 4, and 20 microg/kg), ACh (3.3, 10, and 30 microg/kg), and nitroglycerin (NTG; 1, 10, and 40 microg/kg). After NE, BP increases were significantly attenuated in the ETS group (p = 0.001) but not in animals receiving the antioxidant supplement. At both the middle and high ACh concentrations, ETS (p = 0.03 and p = 0.01, respectively) and hypercholesterolemia (p = 0.03 and p = 0.06, respectively) attenuated ACh-induced reductions in BP. At the highest ACh concentration, vitamins enhanced the reduction in BP (p = 0.002) and blocked the effect of ETS (p = 0.04). Neither ETS nor vitamins influenced NTG-induced decreases in BP. A combined antioxidant-vitamin diet can preserve endothelium-dependent vasodilatation in the hypercholesterolemic rabbit exposed to ETS.

Revascularization in coronary artery disease. A review of randomized trial data

Since the advent of bypass surgery in the late 1960s and catheter-based intervention in the late 1970s, the treatment of coronary artery disease has been revolutionized by the concept of revascularization. Surveys have demonstrated that the practice patterns around the world and within the US are inconsistent for these important treatment options and are often driven by availability and economics rather than evidence-based data. In addition, the studies examining the use of medical therapy, balloon angioplasty, atherectomy, coronary stenting, and bypass surgery are consistently lagging behind the technological advances in this field. This article reviews the data that randomized trials and meta-analyses provide to compare these modalities. We attempt to provide a framework for reasoned clinical decision making to help guide patient care. While the breakpoints between the medicine bottle, cath lab, and operating room will continue to evolve, we offer a revascularization strategy for patient subgroups based on what clinical data supports.

Effects of second-hand smoke and gender on infarct size of young rats exposed in utero and in the neonatal to adolescent period

OBJECTIVES

We sought to assess the effects of second-hand smoke (SHS) and gender on infarct size in young rats exposed in utero or in the neonatal to adolescent period, or both.

BACKGROUND

We previously demonstrated that exposure to SHS increases infarct size in a rat model of ischemia and reperfusion, with a dose-response relation. These results are consistent with epidemiologic studies demonstrating that SHS increases risk of death from heart disease.

METHODS

Thirty-one pregnant female rats were randomly divided into two groups: those exposed to SHS and a control group (non-SHS). After 3 weeks, each rat had given birth to 10 to 12 rats. One hundred one neonatal rats were divided into four groups according to exposure to SHS in utero (SHSu) and randomized to SHS exposure in the neonatal to adolescent period (SHSna). After 12 weeks, all rats were subjected to 17 min of left coronary artery occlusion and 2 h of reperfusion.

RESULTS

Birth mortality was higher in the SHSu group than in the non-SHSu group (11.9% vs. 2.8%, p < 0.001). Body weight of neonatal rats at 3 and 4 weeks in the two SHSu groups was lower than that of rats in the two non-SHSu groups (p < 0.001). Exposure to SHSna increased endothelin-1 levels in plasma (p = 0.001). In all 70 young rats who survived the neonatal period, infarct size (Infarct mass/Risk area x 100%) was greater in the SHSna groups than in the non-SHSna groups (p = 0.005) and in the male groups than in the female groups (p < 0.001).

CONCLUSIONS

Exposure to SHS in the neonatal to adolescent period and male gender increased myocardial infarct size in a young rat model of ischemia and reperfusion. These results are consistent with epidemiologic studies demonstrating that SHS increases the health risk to neonates and adolescents.

Physiological concentrations of estradiol attenuate endothelin 1-induced coronary vasoconstriction in vivo

BACKGROUND

Estrogens are cardioprotective hormones and are reported to have antianginal properties. We examined the effect of physiological concentrations of 17beta-estradiol on coronary reactivity in anesthetized female farm pigs.

METHODS AND RESULTS

Epicardial coronary cross-sectional area (CSA) was assessed by two-dimensional intravascular ultrasound, average coronary peak flow velocity (APV) by intravascular Doppler velocimetry, and coronary blood flow (CBF) was calculated. Dose-response curves to intracoronary endothelin-1 (ET-1, 1 pmol/L to 10 nmol/L), the selective ET(B) receptor agonist sarafotoxin (1 pmol/L to 10 nmol/L), and serotonin (0.1 nmol/L to 1 micromol/L) were assessed before and after a 10-minute infusion of intracoronary estradiol (1 nmol/L). Before estradiol administration, ET-1 induced significant dose-dependent decreases in CSA, APV, and CBF. Estradiol attenuated ET-1-induced epicardial vasoconstriction (P<.001) as well as ET-1-induced decreases in APV (P=.05) and CBF (P=.012). In an additional five pigs, vehicle (DMSO) had no effect on ET-1-induced coronary vasoconstriction. Before estradiol administration, sarafotoxin induced no net change in CSA but induced increases in APV and CBF, the extent of which did not change significantly after estradiol. Serotonin induced small decreases in CSA but increased APV and CBF. Estradiol did not influence serotonin-induced changes in CSA, APV, or CBF.

CONCLUSIONS

We conclude that estradiol attenuates ET-1-induced vasoconstriction, possibly through effects on the ET(A) receptor, because selective ET(B) receptor-induced stimulation with sarafotoxin remained unchanged. Such an effect on the ET(A) receptor may relate to the antianginal properties of estrogens.

Premature coronary artery disease associated with a disruptive mutation in the estrogen receptor gene in a man

BACKGROUND

While estrogens protect against coronary artery disease in women, it is unclear whether they influence cardiovascular function in men. The present report describes coronary vascular abnormalities and the lipoprotein profile of a male patient with estrogen insensitivity caused by a disruptive mutation in the estrogen-receptor gene.

METHODS AND RESULTS

Stress thallium scintigraphy, echocardiography, and electron-beam computed tomography (CT) scanning of the coronary arteries and detailed lipoprotein analysis were performed. Electron-beam CT scanning of the coronary arteries showed calcium in the left anterior descending artery. Lipoprotein analysis showed relatively low levels of total (130 mg/dL), LDL (97 mg/dL), and HDL (34 mg/dL) cholesterol; apolipoprotein A-I (91.7 mg/dL); and lipoprotein(a) (4.1 nmol/L), but normal levels of triglycerides (97 mg/dL) and pre-beta-1-HDL cholesterol (61 microg/mL).

CONCLUSIONS

The absence of functional estrogen receptors may be a novel risk factor for coronary artery disease in men.

Transesophageal echocardiography in rats using an intravascular ultrasound catheter

In vivo assessment of cardiac structure and function in small animals is an important experimental goal, but currently available techniques have significant limitations. A commercially available intravascular ultrasound (IVUS) system was adapted to perform transesophageal echocardiography (TEE) in rats. Twelve Sprague-Dawley rats (270-370 g) were anesthetized with intraperitoneal pentobarbital sodium. A 4.3-Fr, 30-MHz or an 8-Fr, 20-MHz IVUS catheter was inserted into the esophagus to obtain long-axis views of the aortic arch, short-axis views of the ascending aorta, and long-axis views of the pulmonary artery. A preshaped, 8-Fr, 20-MHz catheter was used to obtain short-axis images of the left ventricle (LV) at the midpapillary muscle level, which were used to measure LV diastolic and systolic dimensions (diameters) and to calculate LV mass and fractional shortening. Measurements by TEE were compared with those obtained by transthoracic echocardiography in 6 of 12 rats. Postmortem, the LV was weighed to determine actual LV mass. The correlation coefficients between TEE- and transthoracic echocardiography-calculated LV mass and actual LV mass were 0.94 and 0.88, respectively, and had a good agreement with actual LV mass. Inter- and intraobserver variability of TEE measurements was <10%. IVUS instrumentation may offer an alternative technique for the accurate, serial assessment of LV dimensions, mass, and systolic function and a means of imaging the great vessels in small laboratory animals.

Frequency, duration, magnitude, and consequences of myocardial ischemia during intracoronary ultrasonography

To determine the frequency, duration, magnitude, and possible adverse effects of ischemia during intracoronary ultrasonography, real-time standard 12-lead electrocardiograms were recorded before, during, and after ultrasonography. Ischemia was defined as new-onset ST segment deviation of > or = 1 mm in one or more leads, measured at J + 80 msec. The magnitude of ischemia was expressed as the sum of absolute ST segment deviations across 12 leads. Eighteen (67%) of 27 patients had ischemia during intracoronary ultrasonography. The electrocardiogram resembled the characteristic pattern observed with occlusion of the vessel under study, involving ST segment elevation in contiguous leads in 89% of patients. A higher proportion of women (88%) had ischemia than men (58%), and women had smaller arterial lumenal areas compared with men (6.3 vs 9.1 mm2; p < 0.05). Individuals with ischemia were smaller than those without ischemia (body surface area = 1.99 vs 1.79 m2; p = 0.01). The mean duration of ischemia was 4 minutes and the mean 12-lead ST segment deviation score was 8.5 mm (maximum 20.5 mm). No patient with ischemia during ultrasonography had complications. Ischemia is common during intracoronary ultrasonography, particularly in women and individuals with smaller vessels; however, no adverse outcomes occur as a result.

Sex hormones and vascular reactivity

It is increasingly recognized that sex steroids have, among many other effects, the ability to cause vasodilation. The vasodilatory effects of estradiol have been the best documented and described. At low concentrations, estradiol has the ability to improve impaired endothelium dependent (nitric oxide mediated) relaxation in estrogen deficient subjects. At high concentrations, estradiol causes vasodilation principally by endothelium independent mechanisms, in a gender independent fashion, which appear to involve a number of pathways such as ATP-dependent K+ channels. Testosterone also has ability, at higher doses, to cause vasodilation of the coronary circulation, in a gender independent fashion. The mechanisms of sex steroid-induced vasodilation are reviewed in this article.

Chronic dietary L-arginine prevents endothelial dysfunction secondary to environmental tobacco smoke in normocholesterolemic rabbits

Our goal was to determine whether environmental tobacco smoke causes endothelial dysfunction in the absence of hypercholesterolemia and whether such an effect can be prevented by supplementation with L-arginine. Environmental tobacco smoke exposure is associated with an increase in coronary artery disease events and mortality. We have previously demonstrated that environmental tobacco smoke causes endothelial dysfunction and atherosclerosis in rabbits with diet-induced hypercholesterolemia and atherosclerosis and that chronic dietary L-arginine supplementation prevents this. The effects of L-arginine supplementation (2.25% solution ad libitum) and environmental tobacco smoke (smoking chambers for 10 weeks) were examined with a 2 x 2 design in 32 rabbits fed a normal diet. Acetylcholine, calcium ionophore A23187, and nitroglycerin-induced vasorelaxation were assessed in aortic rings precontracted with phenylephrine. Endothelial L-arginine levels were measured by chromatography. Chronic L-arginine supplementation increased serum (P < .001) and endothelial (P = .003) L-arginine levels. Environmental tobacco smoke reduced endothelium-dependent acetylcholine-induced relaxation, and L-arginine blocked this adverse effect (P = .04). Environmental tobacco smoke tended to increase phenylephrine-induced contraction (P = .06). Neither environmental tobacco smoke nor L-arginine influenced A23187-induced relaxation nor endothelium-independent nitroglycerin-induced relaxation. Endothelial dysfunction secondary to environmental tobacco smoke may occur in the absence of diet-induced hypercholesterolemia and atherosclerosis. Chronic dietary supplementation with a nitric oxide donor such as L-arginine offsets the endothelial dysfunction associated with environmental tobacco smoke in normocholesterolemic rabbits, possibly through substrate loading of the nitric oxide pathway.

Testosterone worsens endothelial dysfunction associated with hypercholesterolemia and environmental tobacco smoke exposure in male rabbit aorta

OBJECTIVES

To assess the effects of interaction of sex hormones, hypercholesterolemia (HC) and environmental tobacco smoke (ETS) exposure on endothelium-dependent relaxation, we examined vascular reactivity in vitro in an animal model of atherogenesis.

BACKGROUND

Animal and human studies indicate the presence of interactions between classic coronary artery disease risk factors and endothelium-dependent relaxation. Sex hormones have also been shown to influence release of endothelium-derived relaxing factor.

METHODS

New Zealand White rabbits were randomized to receive either an HC diet (n = 8) or ETS exposure plus HC diet (n = 8). Eight rabbits receiving a normal diet, without exposure to ETS, served as the control group. The HC diet consisted of 3% soybean oil and 0.3% cholesterol by weight over 13 weeks. The source of ETS was sidestream smoke of 4 cigarettes/15 min, 6 h/day, 5 days/week over 10 weeks in a smoking chamber. Rabbits were killed, and fresh aortic rings were harvested and maintained in oxygenated Krebs solution in an organ bath at 37 degrees C. Rings were precontracted with norepinephrine and exposed to acetylcholine in increasing doses, and isometric tension was recorded. Rings were also exposed to physiologic concentrations (1 nmol/liter) of either 17-beta-estradiol, testosterone or progesterone before pre-contraction with norepinephrine and relaxation with acetylcholine. Endothelium-independent relaxation was studied using nitroglycerin. The surface area of the ring covered by lipids was measured by Sudan IV staining.

RESULTS

HC and ETS significantly reduced endothelium-dependent relaxation (p = 0.01 and p < 0.0005, respectively) and caused atherogenesis (p < 0.0005 and p = 0.047, respectively) but did not affect endothelium-independent relaxation. Incubation with estradiol and estradiol plus progesterone did not influence endothelium-dependent relaxation. Testosterone reduced endothelium-dependent relaxation (p = 0.049) and augmented the endothelial dysfunction associated with ETS exposure and HC (p = 0.03).

CONCLUSIONS

Both HC and ETS are atherogenic and impair endothelial function but do not affect endothelium-independent relaxation. Physiologic levels of estradiol and estradiol plus progesterone do not affect endothelium-dependent relaxation. Physiologic levels of testosterone impair relaxation and augment the endothelial dysfunction associated with ETS exposure and HC.

Fetoscopic and open transumbilical fetal cardiac catheterization in sheep. Potential approaches for human fetal cardiac intervention

BACKGROUND

Shortening the prenatal disease course of severe aortic and pulmonary stenoses by balloon valvuloplasty may diminish their postnatal expression. The purpose of this study in fetal sheep was to assess the feasibility of fetoscopic and open transumbilical fetal cardiac catheterization guided by fetal transesophageal echocardiography to provide alternative approaches for human fetal cardiac intervention.

METHODS AND RESULTS

We studied a total of nine fetal sheep (95 to 103 days of gestation; term = 145 to 150 days) and performed transumbilical fetal cardiac catheterization by a minimally invasive fetoscopic (n = 6) or an open fetal surgical approach (n = 3). Monitored by fetal transesophageal echocardiography, with an 8F or 10F, 10-MHz intravascular ultrasound catheter we placed guidewires and interventional catheters via the umbilical arterial route into the fetal heart. In three of the fetuses, we created supravalvar pulmonary artery stenosis by open fetal cardiac surgery After fetal and maternal recovery, we exteriorized these fetuses and performed open transumbilical fetal cardiac catheterization with successful pulmonary arterial angioplasty in two. Three fetuses survived fetoscopic transumbilical catheterization for 1 or 2 days and died most likely of blood loss after sheath dislodgment (n = 1) or removal (n = 2). By securing the sheath insertion site with a suture, we prevented sheath dislodgment and minimized bleeding during sheath removal in three fetuses. These fetuses then survived fetoscopic transumbilical fetal cardiac catheterization for 1 to 2 weeks before being killed.

CONCLUSIONS

This study in fetal sheep demonstrates that fetoscopic and open transumbilical fetal cardiac catheterization are feasible and, guided by fetal transesophageal echocardiography, provide potential alternative approaches for human fetal cardiac intervention.

Use of intravascular ultrasound in evaluating repeated balloon rupture during coronary stenting

Balloon rupture during coronary angioplasty is a well-recognized complication of PTCA. Coronary angiography commonly fails to elicit the cause of balloon perforation. We present a case with multiple balloon rupture during additional high-pressure inflations of a Palmaz-Schatz stent where intravascular ultrasound was useful in revealing a calcified lesion protruding through the struts of the stent.

Testosterone induces dilation of canine coronary conductance and resistance arteries in vivo

BACKGROUND

Although estrogens have been shown to be vasoactive hormones, the vascular effects of testosterone are not well defined. Like estrogen, testosterone causes relaxation of isolated rabbit coronary arterial segments. We examined the vasodilator effects of testosterone in vivo in the coronary circulation and the potential mechanisms of its actions.

METHODS AND RESULTS

Using simultaneous intravascular two-dimensional and Doppler ultrasound, we examined the effect of intracoronary testosterone in coronary conductance and resistance arteries in 10 anesthetized dogs (5 male, 5 female). We also assessed the contribution of NO, prostaglandins, ATP-sensitive K+ channels, and classic estrogen receptors to testosterone-induced vasodilation. Testosterone induced a significant increase in cross-sectional area, average coronary peak flow velocity, and calculated volumetric coronary blood flow at the 0.1 and 1 mumol/L concentrations. This effect was independent of sex. Pretreatment with N omega-nitro-L-arginine methyl ester to block NO synthesis decreased testosterone-induced increase in cross-sectional area, average coronary peak flow velocity, and coronary blood flow. Pretreatment with glybenclamide to assess the role of ATP-sensitive K+ channels did not influence testosterone-induced dilation in epicardial arteries but did attenuate its effect in the microcirculation. Pretreatment with indomethacin or the classic estrogen-receptor antagonist ICI 182,780 did not alter testosterone-induced changes.

CONCLUSIONS

Short-term administration of testosterone induces a sex-independent vasodilation in coronary conductance and resistance arteries in vivo. Acute testosterone-induced coronary vasodilation of epicardial and resistance vessels is mediated in part by endothelium-derived NO. ATP-sensitive K+ channels appear to play a role in the vasodilatory effect of testosterone in resistance arteries.

Comparison of adenosine to dipyridamole in degree of coronary hyperemic response in heart transplant recipients

Transplant coronary vasculopathy is associated with endothelial dysfunction. Microvascular function, assessed as coronary flow reserve, has been reported to be normal. We used intracoronary ultrasound technology to simultaneously assess conductance and resistance vessel function in response to standard dosages of the vasodilators adenosine and dipyridamole. Coronary hemodynamic changes were assessed in 11 heart transplant recipients, at a mean duration of 784 +/- 516 days after transplantation, using a 3.2Fr or 4.3Fr, 30-MHz ultrasound imaging catheter over a 0.014-inch Doppler guidewire. Measures of coronary average peak flow velocity (APV) and coronary cross-sectional area (CSA) were used to calculate volumetric flow during intravenous infusions of adenosine (140 micrograms/kg/min over 4 minutes) and dipyridamole (140 micrograms/kg/min over 4 minutes). Flow reserve was assessed as a ratio of maximal pharmacologically induced flow to steady baseline flow before infusion. Increase in APV (261.9% vs 194.6%, p = 0.005), lumenal CSA (+11.8% vs +4.2%, p = 0.01), peak volumetric blood flow (515.8 vs 317.2 ml/min, p = 0.007), and coronary flow reserve (2.93 +/- 0.74 vs 1.99 +/- 0.53, p < 0.001) were higher with adenosine than dipyridamole. Both agents caused similar decreases in systemic blood pressure and little change in heart rate. Adenosine appears to be a more potent coronary vasodilator than dipyridamole in denervated human transplant subjects. Adenosine has a vasodilator effect at the epicardial and microvascular levels, resulting in an overall increase in volumetric flow. Flow reserve in response to both endothelium-independent agents is decreased in comparison with previously established values, but the attenuation is greater with dipyridamole.