bluuebunny/crossref_metadata_2025 huggingface dataset:
Vascular Endothelin-1 Gene Expression and Effect on Blood Pressure of Chronic ET
A
Endothelin Receptor Antagonism After Nitric Oxide Synthase Inhibition With
L-
NAME in Normal Rats
Authors: Sventek Pavol , Turgeon Andre´ , Schiffrin Ernesto L.
Published: June 2012

Background
Vascular expression of the endothelin-1 gene may be associated with severe vascular hypertrophy. Because in rats, inhibition of NO synthase with the
l
-arginine analogue
N
ω
-nitro-
l
-arginine methyl ester (L-NAME) induces blood pressure elevation associated with little cardiovascular hypertrophy, we studied vascular endothelin-1 gene expression in L-NAME–treated rats and the effects of chronic endothelin antagonism.

Methods and Results
Sprague-Dawley rats received 100 mg·kg
−1
·d
−1
L-NAME in their drinking water for 3 weeks. Systolic blood pressure rose to 189±3 mm Hg (
P
<.001 versus control rats). By Northern blot analysis, endothelin-1 mRNA levels were similar in aortas and mesenteric arteries of control and L-NAME–treated rats. The blood pressure of L-NAME hypertensive rats treated with the ET
A
-selective endothelin receptor antagonist A-127722 for 3 weeks at a low dose (10 mg·kg
−1
·d
−1
) and a high dose (30 mg·kg
−1
·d
−1
) was not different from that of rats receiving L-NAME but not the endothelin antagonist. Treatment with the ACE inhibitor cilazapril lowered the blood pressure of L-NAME–treated rats equally whether or not they were receiving the ET
A
antagonist.

Conclusions
These results indicate that the endothelin system does not participate to an important degree in the mechanisms leading to elevated blood pressure after chronic NO synthase inhibition with L-NAME in normal rats. In the chronic model of L-NAME–induced hypertension, blockade of the renin-angiotensin system does not unmask an endothelin-dependent vasopressor tone. In addition, either NO does not regulate vascular endothelin-1 gene expression or L-NAME exerts an inhibitory effect on endothelin expression in blood vessels.
In Vivo Gene Transfection of Human Endothelial Cell Nitric Oxide Synthase in Cardiomyocytes Causes Apoptosis-Like Cell Death
Authors: Kawaguchi Hiroyuki , Shin Wee Soo , Wang Yuepeng , Inukai Masao , Kato Masayoshi , Matsuo-Okai Yoko , Sakamoto Aiji , Uehara Yoshio , Kaneda Yasufumi , Toyo-oka Teruhiko
Published: June 2012

Background
Nitric oxide (NO) has various actions on the cardiovascular system, although its pathophysiological significance in myocardial cells remains obscure. The aim of the present study was to identify direct NO actions on cardiomyocytes by gene transfection in vivo using a newly developed vector under physiological conditions.

Methods and Results
Liposomes containing the β-galactosidase (β-gal) gene alone or with the human endothelial cell nitric oxide synthase (ecNOS) gene were coated with UV-inactivated Sendai virus and injected into the left ventricular wall of rat heart in vivo. Histological examination confirmed that the transfection efficiency was comparable to adenovirus-mediated transfection and that the new vector per se caused no inflammation. β-Gal expression was confined to cardiomyocytes between two intercalated discs, suggesting that the transfected gene did not permeate the discs. An immunohistochemical study showed that cotransfection of the ecNOS gene induced massive myocardial cell shrinkage in both transfected cells and the adjacent myocytes in a time- and dose-dependent manner. Histochemical findings in shrunk cells coincided with apoptosis as identified by terminal deoxynucleotidyl transferase–mediated dUTP-biotin nick-end labeling. Electron microscopy of the lesion revealed myofibrillar degradation and accumulation of mitochondria but no apoptotic bodies. Pretreatment with the NOS inhibitor N
ω
-nitro-
l
-arginine methyl ester abolished these morphological alterations.

Conclusions
The efficient expression of the human ecNOS gene in vivo suggests that NO or its toxic metabolite caused myocardial degradation, a part of which was compatible with apoptosis of the transfected cardiomyocytes themselves and the adjacent cells as a paracrine effect. These morphological features mimicked acute myocarditis or ischemic injury.
Regulation of Fibrillar Collagen Gene Expression and Protein Accumulation in Volume-Overloaded Cardiac Hypertrophy
Authors: Namba Takashi , Tsutsui Hiroyuki , Tagawa Hirofumi , Takahashi Masaru , Saito Keiko , Kozai Toshiyuki , Usui Makoto , Imanaka-Yoshida Kyoko , Imaizumi Tsutomu , Takeshita Akira
Published: June 2012

Background
Interstitial collagen accumulation has been extensively demonstrated to be increased at both mRNA and protein levels in pressure-overloaded cardiac hypertrophy. However, few data are available regarding the effects of volume overload on myocardial collagens.

Methods and Results
To determine whether the alterations of collagens may occur in volume-overloaded cardiac hypertrophy, we measured collagen types I and III mRNA levels and protein accumulation in left ventricular (LV) myocardium of rats at 3, 7, and 28 days after the creation of an aortocaval (AC) shunt. Eccentric LV hypertrophy was produced in rats with AC shunting. Northern blot analysis on RNA extracted from LV tissue indicated that the steady state mRNA levels for both type I and III collagen were persistently upregulated in AC shunt rats compared with sham-operated control rats. In contrast, the biochemical collagen protein concentration and morphometric collagen volume fraction were comparable between sham-operated control and AC shunt rats at any study time point. Furthermore, the immunohistochemical staining of types I and III collagen and Sirius red staining on myocardial tissue sections revealed no significant alterations in the distribution or density of fibrillar collagens in AC shunt rats. Tissue collagenase activity was not different between control and AC shunt rats after 28 days.

Conclusions
Cardiac volume overload increases LV collagen mRNA as does pressure overload. However, in contrast to pressure-overloaded hypertrophy, the upregulation of collagen transcriptional activity does not result in subsequent myocardial fibrosis in volume-overloaded hypertrophy due to AC shunting. Therefore, the upregulation of collagen gene expression and protein accumulation might be different in pressure-overloaded and volume-overloaded hypertrophy.
Cardiac Risk Stratification for High-Risk Vascular Surgery
Authors: Bartels Claus , Bechtel J. F. Matthias , Hossmann Volker , Horsch Svante
Published: June 2012

Background
The best strategy for cardiac risk assessment before high-risk vascular surgery remains controversial. A cardiac risk stratification protocol was evaluated in patients undergoing high-risk vascular surgery. Our investigation paralleled the elaboration of the American College of Cardiology/American Heart Association (ACC/AHA) Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery and is highly comparable to the proposed guidelines.

Methods and Results
A cardiac risk stratification protocol was evaluated prospectively in 203 patients scheduled for aortic surgery. Key points of the study were cardiac mortality/morbidity and cost-effectiveness. Patients were stratified into low (n=101), intermediate (n=79), and high (n=23) cardiac risk after clinical predictors. After stratification, the degree of estimated functional capacity assessed by treadmill exercise and daily living activities and expressed by metabolic equivalents (METs) was critical for further cardiac evaluation. In intermediate-risk patients with an estimated functional capacity <5 METs and in all high-risk patients, noninvasive cardiac testing and/or subsequent medical care were performed. Noninvasive testing was considered necessary in 41 patients, coronary angiography in 7, and myocardial revascularization in 1. Overall hospital mortality was 3.5%. Cardiac mortality and morbidity were 1% and 12.4%, respectively.

Conclusions
Cardiac risk stratification for high-risk vascular surgery patients, according to a protocol similar to the ACC/AHA Guidelines for Cardiovascular Evaluation for Noncardiac Surgery, demonstrated excellent clinical outcome. This approach appears to be a safe and economical strategy for preoperative cardiac evaluation.
Assessment of a Newly Recognized Association
Authors: Blanc Jean-Jacques , L'Heveder Gildas , Mansourati Jacques , Tea Say Hak , Guillo Philippe , Mabin Dominique
Published: June 2012

Background
Carotid sinus syndrome has been reported recently to be associated with chronic denervation of the sternocleidomastoid muscles. To further understand the relationship between carotid mechanoreceptors and sternocleidomastoid denervation, the present study investigated the relation between the results of carotid sinus massage and electromyographic activity of the sternocleidomastoid muscles in patients without syncope.

Methods and Results
Patients were selected prospectively if they fulfilled strict exclusion criteria, particularly the absence of a history of syncope, pacemaker implantation, or drugs known to modify the behavior of the autonomic nervous system. A right and left carotid massage was performed for 10 seconds in 30 patients (22 men; mean age, 67.3±6.5 years). The results (monitoring for heart rate and blood pressure) were classified as normal, doubtful, or hypersensitive carotid sinus. Sternocleidomastoid electromyography activity was recorded from the right and left sides, and the results were classified as normal, moderate denervation, and severe denervation. Carotid sinus massage was normal in 13 patients (43%), doubtful in 9 (30%), and abnormal in 8 (27%). Electromyographic activity of the sternocleidomastoids was normal in 13 patients (43%) and revealed moderate denervation in 7 (24%) and severe chronic denervation in 10 (33%). The results of carotid sinus massage and sternocleidomastoid electromyography were highly concordant in each patient (κ=.592,
P
<.00001) and in each side (right, κ=.381,
P
<.03; left, κ=.390,
P
<.01).

Conclusions
Carotid sinus hypersensitivity and chronic denervation is a common finding in individuals older than 50 years of age. These two entities are significantly related, suggesting a pathophysiological relation of one to the other.
Cytomegalovirus Infection–Enhanced Cardiac Allograft Vasculopathy Is Abolished by DHPG Prophylaxis in the Rat
Authors: Lemström Karl , Sihvola Roope , Bruggeman Cathrien , Häyry Pekka , Koskinen Petri
Published: June 2012

Background
A wealth of clinical and experimental evidence exists for cytomegalovirus (CMV) infection as an accelerating factor in the development of cardiac allograft vasculopathy. In this study, the impact of 9-(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG) on rat CMV infection–enhanced cardiac allograft vasculopathy is investigated.

Methods and Results
Heterotopic rat cardiac allografts were performed from the DA to the WF rat strain, and the recipients were immunosuppressed with cyclosporine A 2 mg·kg
−1
·d
−1
SC for a period of 90 days until the end of experiment. Two groups of recipients were infected intraperitoneally with 10
5
plaque-forming units of rat CMV, whereas one group was left noninfected and used as controls. One group of rat CMV–infected rats was treated with DHPG with an initial dose of 20 mg/kg IP and a maintenance dose of 10 mg/kg IP twice a day from 1 day before transplantation to 30 days after transplantation. Compared with noninfected rats, rat CMV infection was associated with a significant increase in intimal thickening, from 0.68±0.10 to 1.30±0.12 score units (
P
<.01), and double the number of vessels affected (
P
<.01). DHPG treatment significantly reduced intimal thickening in rat CMV–infected rats, from 1.30±0.12 to 0.68±0.13 score units (
P
<.01), and halved the number of vessels affected (
P
<.01).

Conclusions
The present results demonstrate that DHPG prophylaxis entirely abolishes the accelerating effect of rat CMV infection on cardiac allograft vasculopathy in immunosuppressed rat recipients, which is consistent with our earlier findings demonstrating a similar effect in nonimmunosuppressed rat aortic allografts. Taken together, these results suggest that DHPG might be useful in the prevention of CMV-accelerated cardiac allograft vasculopathy among heart transplant recipients.
Transmyocardial Laser Revascularization
Authors: Gassler Nikolaus , Wintzer Hanns-Olof , Stubbe Hans-Martin , Wullbrand Andreas , Helmchen Udo
Published: June 2012

Background
The creation of transmyocardial channels from the epicardium to the left ventricular cavity with the use of a CO
2
laser is a modern approach in the treatment of patients with chronic ischemic cardiac disease. The histological features of human myocardium at different times after transmyocardial laser therapy have not been previously described. We had the opportunity to examine hearts from patients who died without clinical evidence of a persistent therapeutic effect at 3, 16, and 150 days after transmyocardial laser revascularization (TMR), respectively.

Methods and Results
We grossly localized the laser-created channels in unfixed and formalin-fixed tissue. Three ventricular levels were defined for cutting the hearts into four segments. Then, transmural blocks were excised and cut crosswise and lengthwise for histological investigation through the use of established staining methods. On day 3, laser-induced channels were filled with abundant granulocytes and thrombocytes, fibrinous network, and detritus and were surrounded by severe myocardial necrosis. Furthermore, the epicardial and endocardial portions were obstructed by fibrinous network and microclots. Granulocytes were mostly absent on day 16; in addition, the channels were filled with erythrocytes or fibrinous network. On day 150, we observed a string of cicatricial tissue admixed with a polymorphous blood-filled capillary network and small veins, which very rarely had a continuous wrinkled link to the left ventricular cavity.

Conclusions
We found different stages of wound healing in human nonresponder myocardium after TMR, resulting in scarred tissue that displayed capillary network and dilated venules without evidence of patent and endothelialized laser-created channels. Experimental studies are necessary to analyze the morphological basis for TMR-mediated effects in human responder myocardium.
Prediction of Outcome of Patients With Life-Threatening Ventricular Arrhythmias Treated With Automatic Implantable Cardioverter-Defibrillators Using SPECT Perfusion Imaging
Authors: Gioia Giuseppe , Bagheri Bruce , Gottlieb Charles D. , Schwartzman David S. , Callans David J. , Marchlinski Frank E. , Heo Jaekyeong , Iskandrian Ami E.
Published: June 2012

Background
In the present study, we examined the predictors of outcome of 103 patients with coronary artery disease and left ventricular dysfunction who had life-threatening ventricular arrhythmias and were treated with implantable cardioverter-defibrillators with the use of single-photon emission computed tomography (SPECT).

Methods and Results
During a mean follow-up of 29 months, there were 29 cardiac deaths. In comparison with patients who died, survivors had less diabetes mellitus (45% versus 19%,
P
<.007), higher left ventricular ejection fraction (23±9% versus 27±11%,
P
=.04), and fewer perfusion defects as determined with stress SPECT (15±5 versus 12±5,
P
<.004). Most of the perfusion defects were fixed, indicative of scarring; the extent of reversible defects did not differ (2±3 in survivors and 3±4 in nonsurvivors). Multivariate Cox survival analysis identified the number of fixed defects as the only independent predictor of death (χ
2
=10,
P
=.002). There were six deaths among 42 patients (14%) with <8 fixed defects compared with 23 deaths among 61 patients (38%) with ≥8 defects (
P
=.005). The 4-year survival was better in patients with <8 segmental fixed defects than in those with ≥8 fixed defects (80% versus 36%) (χ
2
=8,
P
=.005).

Conclusions
The myocardial perfusion pattern is an important determinant of outcome in patients with life-threatening ventricular arrhythmias who are treated with a implantable cardioverter-defibrillator. The extent of scarring separates patients into high- and low-risk groups with a 2.7-fold difference in death rate.
Four Novel
KVLQT1
and Four Novel
HERG
Mutations in Familial Long-QT Syndrome
Authors: Tanaka Toshihiro , Nagai Ryozo , Tomoike Hitonobu , Takata Shigeo , Yano Katsusuke , Yabuta Keijiro , Haneda Noriyuki , Nakano Osami , Shibata Akira , Sawayama Toshitami , Kasai Hideaki , Yazaki Yoshio , Nakamura Yusuke
Published: June 2012

Background
Familial long-QT syndrome (LQTS) is characterized by prolonged ventricular repolarization. Clinical symptoms include recurrent syncopal attacks, and sudden death may occur due to ventricular tachyarrhythmias. Three genes responsible for this syndrome (
KVLQT1
,
HERG
, and
SCN5A
) have been identified so far. We investigated mutations of these genes in LQTS families.

Methods and Results
Thirty-two Japanese families with LQTS were brought together for screening for mutations. Genomic DNA from each proband was examined by the polymerase chain reaction–single-strand conformation polymorphism technique followed by direct DNA sequencing. In four of the families, comprising 16 patients, mutations were identified in
KVLQT1
; five other families (9 patients) segregated mutant alleles of
HERG
. All 25 of these patients carried the specific mutations present in their respective families, and none of 80 normal individuals carried these alleles. Mutations were confirmed by endonuclease digestion or hybridization of mutant allele–specific oligonucleotides. No mutation in
SCN5A
was found in any family.

Conclusions
We identified nine different mutations among 32 families with LQTS. Eight of these were novel and account for 25% of all types of mutations reported to date. Such a variety of mutations makes it difficult to screen high-risk groups using simple methods such as endonuclease digestion or mutant allele–specific amplification.
Induction of Monocyte Chemoattractant Protein-1 in the Small Veins of the Ischemic and Reperfused Canine Myocardium
Authors: Kumar Ajith G. , Ballantyne Christie M. , Michael Lloyd H. , Kukielka Gilbert L. , Youker Keith A. , Lindsey Merry L. , Hawkins Hal K. , Birdsall Holly H. , MacKay Charles R. , LaRosa Gregory J. , Rossen Roger D. , Smith C. Wayne , Entman Mark L.
Published: June 2012

Background
Healing after myocardial infarction is characterized by the presence of macrophages in the infarcted area. Since augmented monocyte influx has been implicated as a potential mechanism for improved healing after reperfusion, we wished to study the induction of monocyte chemoattractant protein-1 (MCP-1) during reperfusion.

Methods and Results
The cDNA for MCP-1 was cloned from a canine jugular vein endothelial cell (CJVEC) library and exhibited 78% identity with the deduced amino acid sequence of human MCP-1. Samples of myocardium were taken from control and ischemic segments after 1 hour of ischemia and various times of reperfusion; total RNA was isolated from myocardial samples and probed with a cDNA probe for canine MCP-1. Induction of MCP-1 mRNA occurred only in previously ischemic segments within the first hour of reperfusion, peaked at 3 hours, and persisted throughout the first 2 days of reperfusion. In the absence of reperfusion, no significant MCP-1 induction was seen. Both ischemic (but not preischemic) cardiac lymph and human recombinant TNF-α induced MCP-1 in CJVECs. MCP-1 was identified by immunostaining on infiltrating cells and venular (but not arterial) endothelium by 3 hours. In contrast, in situ hybridization showed MCP-1 mRNA to be confined to the endothelium of small veins (venules) 10 to 70 μm in diameter.

Conclusions
MCP-1 mRNA is induced in the endothelium of a specific class of small veins immediately after reperfusion. MCP-1 induction is confined to the previously ischemic area that has been reperfused. We suggest a significant role for MCP-1 in monocyte trafficking in the reperfused myocardium.
Effects of GP IIb/IIIa Receptor Monoclonal Antibody (7E3), Heparin, and Aspirin in an Ex Vivo Canine Arteriovenous Shunt Model of Stent Thrombosis
Authors: Makkar Raj R. , Litvack Frank , Eigler Neal L. , Nakamura Masato , Ivey Pamela A. , Forrester James S. , Shah Prediman K. , Jordan Robert E. , Kaul Sanjay
Published: June 2012

Background
Thrombosis is an important limitation of metallic coronary stents, especially in smaller vessels in which shear rates are high. Monoclonal antibody to platelet glycoprotein IIb/IIIa receptor (7E3) has been shown to inhibit shear-induced platelet aggregation. In this study, we compared the effects of 7E3, heparin, and aspirin on stent thrombosis in an ex vivo arteriovenous shunt model of high-shear blood flow.

Methods and Results
An ex vivo arteriovenous shunt was created in 10 anesthetized dogs. Control rough-surface slotted-tube nitinol stents (n=72) expanded to 2 mm in diameter in a tubular perfusion chamber were interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100 s
−1
for 20 minutes. The animals were treated with intravenous murine 7E3 (Fab′)
2
(0.2, 0.4, and 0.8 mg/kg), heparin (100 U/kg), or aspirin (10 mg/kg). Effects of the test agents on thrombus weight, platelet aggregation, platelet P-selectin expression, bleeding time, and activated clotting time (ACT) were quantified. 7E3 reduced stent thrombosis by 95% (20±1 to 1±1 mg,
P
<.001) and platelet aggregation by 94% (14±2 to 1±1 Ω,
P
<.001) at the highest dose (0.8 mg/kg). 7E3 significantly prolonged bleeding time but had no effect on ACT and platelet P-selectin expression. Heparin prolonged ACT but had no significant effect on stent thrombosis or platelet aggregation. Aspirin, although it inhibited platelet aggregation by 65%, had no effect on stent thrombosis (19±2 versus 20±1 mg in controls).

Conclusions
7E3 produced a dose-dependent inhibition of acute stent thrombosis under high-shear flow conditions. Stent thrombosis was resistant to heparin and aspirin. Thus, 7E3 may be an effective agent for preventing stent thrombosis.
Vascular Endothelial Growth Factor/Vascular Permeability Factor Augments Nitric Oxide Release From Quiescent Rabbit and Human Vascular Endothelium
Authors: van der Zee Rien , Murohara Toyoaki , Luo Zhengyu , Zollmann Frank , Passeri Jonathan , Lekutat Carsten , Isner Jeffrey M.
Published: June 2012

Background
Vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF) is an endothelial cell (EC) mitogen. This feature is considered central to the documented role of VEGF/VPF in promoting angiogenesis. More recent evidence suggests that VEGF/VPF may also serve a “maintenance” function, modulating various aspects of EC biology. In the present study, we sought to determine the extent to which VEGF/VPF may stimulate the release of NO from normal ECs.

Methods and Results
VEGF/VPF produced a dose-dependent rise in NO concentration ([NO]) from vascular segments of rabbit thoracic aorta, pulmonary artery, and inferior vena cava. In comparison to stimulation with acetylcholine, the onset of increased [NO] after administration of VEGF/VPF was slower, reaching a maximum value after 8 minutes. Preincubation of the aortic segments with
l
-arginine raised by twofold both baseline [NO] and [NO] stimulated by addition of 2.5 μg/mL VEGF/VPF. Removal of CaCl
2
from the Krebs solution, disruption of the endothelium, and administration of
N
G
-monomethyl-
l
-arginine abrogated the stimulatory effect of 10 μg/mL VEGF/VPF. Similar findings were documented with an NO-specific polarographic electrode to measure NO released from cultured human umbilical vein ECs.

Conclusions
VEGF/VPF stimulates production of NO from rabbit and human ECs. This finding (1) constitutes inferential evidence for the presence of functional VEGF/VPF receptors on quiescent endothelium of the adult rabbit as well as human ECs and (2) supports the notion that putative maintenance functions of VEGF/VPF may include regulation of baseline synthesis and/or release of EC NO.
Left Ventricular Assist Device Infection Is Associated With Increased Mortality but Is Not a Contraindication to Transplantation
Authors: Herrmann Mathias , Weyand Michael , Greshake Britta , von Eiff Christof , Proctor Richard A. , Scheld Hans H. , Peters Georg
Published: June 2012

Background
Left ventricular assist devices (LVADs) are increasingly used as a bridge to transplantation. Infection is a frequent and major complication associated with the use of these devices; however, the correlation of infection and outcome has not yet been evaluated in a prospective fashion.

Methods and Results
Twenty-five patients (24 male, 1 female) with end-stage cardiac failure and resulting organ dysfunction were included. Patients were bridged with the Novacor N100 portable LVAD (median duration of support, 55 days) and were evaluated prospectively by device surface cultures on explantation, molecular typing of isolates, and correlation of infection with survival to transplant. Twelve (48%) of 25 patients had LVAD infection as defined by recovery of multiple isolates of identical genotype from the device surface. Whereas only 5 (42%) of 12 patients with LVAD infection survived until transplantation, 11 (85%) of 13 patients without infection were successfully transplanted (
P
<.05). Death of the 7 patients with proven LVAD infection was associated with multiple organ failure or other signs of acute infection.

Conclusions
LVAD infection is associated with a significantly decreased survival probability. It does not preclude successful bridging but rather may pose an indication for urgent transplantation.
Role of Bradykinin in Mediating Vascular Effects of Angiotensin-Converting Enzyme Inhibitors in Humans
Authors: Hornig Burkhard , Kohler Christoph , Drexler Helmut
Published: June 2012

Background
The angiotensin-converting enzyme (ACE) not only generates angiotensin II but is also the main enzyme that destroys bradykinin. It has been hypothesized, therefore, that bradykinin is involved in the vascular effects of ACE inhibitors. However, its contribution has never been demonstrated in humans because of the lack of specific bradykinin receptor antagonists.

Methods and Results
High-resolution ultrasound and Doppler were used to measure radial artery diameter and blood flow in 10 healthy volunteers. The vascular effects of the ACE inhibitor quinaprilat, the selective bradykinin B
2
-receptor antagonist icatibant, and their combination were determined at rest, during reactive hyperemia (with increased flow causing endothelium-mediated, flow-dependent dilation), and during sodium nitroprusside, causing endothelium-independent dilation. Neither icatibant nor quinaprilat affected arterial diameter or blood flow at rest. However, icatibant reduced flow-dependent dilation by 33%, and quinaprilat increased flow-dependent dilation over baseline by 46%. After coinfusion of quinaprilat and icatibant, flow-dependent dilation was reduced to a similar extent as after infusion of icatibant alone.

Conclusions
ACE inhibition enhances flow-dependent, endothelium-mediated dilation in humans by a bradykinin-dependent mechanism. This observation indicates that accumulation of endogenous bradykinin is involved in the vascular effects of ACE inhibitors in humans.
Electron Microscopic Studies of Phenotypic Modulation of Smooth Muscle Cells in Coronary Arteries of Patients With Unstable Angina Pectoris and Postangioplasty Restenosis
Authors: Chen Ying-Hwa , Chen Yuh-Lien , Lin Shing-Jong , Chou Chia-Yu , Mar Guang-Yuan , Chang Mau-Song , Wang Shih-Pu
Published: June 2012

Background
Proliferation and matrix protein secretion of coronary smooth muscle cells (SMCs) have been suggested as one of the mechanisms responsible for the development of postangioplasty restenosis and an alternative cause of unstable angina. Phenotypic modulation of SMCs may produce a pool of cells potentially responsive to growth stimulation that can synthesize abundant extracellular matrix. This study tested the hypothesis that phenotypic modulation of SMCs occurred during the evolution of postangioplasty restenosis and unstable angina.

Methods and Results
The SMCs of coronary atherectomy specimens from 24 patients were identified under electron microscope. Volume fractions of synthetic organelles (VFSOs) and other features related to phenotypic modulation of SMCs were measured. The results showed that the VFSO in SMCs from 5 patients with unstable angina (group 2) resembled those from 9 patients with postangioplasty restenosis (group 3; 0.42±0.13 versus 0.36±0.10;
P
=NS), and both were significantly higher than those from 6 patients with stable angina (group 1; 0.21±0.11). Four patients with restenosis lesions who underwent angioplasty >6 months ago (group 4) also had a low VFSO in SMCs (0.19±0.05). This value was significantly less than those in groups 2 and 3 (
P
<.05) but similar to that in group 1.

Conclusions
The coronary lesions from patients with unstable angina resembled those from patients with postangioplasty restenosis in terms of the phenotypic modulation and VFSO in SMCs. Our findings therefore suggest that after phenotypic modulation, the SMCs may become responsive to growth stimulation, with an ability to massively proliferate and synthesize abundant extracellular matrix. These processes may lead to plaque expansion and eventually to the development of unstable angina and restenosis.
Apical Muscular Ventricular Septal Defects Between the Left Ventricle and the Right Ventricular Infundibulum
Authors: Kumar Krishna , Lock James E. , Geva Tal
Published: June 2012

Background
Effective transcatheter or surgical closure of apical muscular ventricular septal defects (VSDs) requires accurate delineation of variable and often complex anatomy. These defects have generally been considered as communications between the apexes of both left and right ventricles.

Methods and Results
Among 50 consecutive patients with multiple muscular VSDs referred for transcatheter device closure between October 1987 and April 1993, a subset of 10 patients (aged 7 days to 28 years) with apical muscular VSDs shared a unique set of anatomic characteristics: (1) large and often single opening in the left ventricle; (2) multiple right ventricular openings in the anterior aspect of the apical septum; and (3) separation of the right ventricular apical region into which the VSDs open from the rest of the right ventricular inflow and outflow by prominent muscle bundles. Additional analysis of the anatomy by use of echocardiography and cineangiography showed that these muscular defects were between the left ventricular apex and right ventricular infundibular apex. In 6 patients, the transcatheter devices used to create a septum in these hearts were placed in the right ventricle, straddling muscle bundles that separated the apical VSD from the rest of the right ventricular inflow and outflow, resulting in incorporation of a portion of the right ventricular infundibular apex into the physiological left ventricle. Three patients had devices placed between the apexes of the left ventricle and the infundibulum. The defect closed spontaneously within the right ventricle in 1 patient. One patient died after surgery for tetralogy of Fallot in situs inversus. The remaining 9 patients were all clinically well at the time of their most recent follow-up visit (follow-up duration, 32±11 months). This distinct type of apical VSD was identified by echocardiography in 20 of 274 patients who were followed up clinically for muscular VSDs.

Conclusions
Left ventricular–infundibular apical VSDs constitute a distinct morphological type of muscular VSD that can be distinguished by echocardiography and cineangiography. In selected cases, the infundibular apex can be separated from the rest of the right ventricular inflow and outflow to eliminate flow across these defects.
Norepinephrine Induces the
raf
-1 Kinase/Mitogen-Activated Protein Kinase Cascade Through Both α
1
- and β-Adrenoceptors
Authors: Yamazaki Tsutomu , Komuro Issei , Zou Yunzeng , Kudoh Sumiyo , Shiojima Ichiro , Hiroi Yukio , Mizuno Takehiko , Aikawa Ryuichi , Takano Hiroyuki , Yazaki Yoshio
Published: June 2012

Background
Although norepinephrine induces cardiac hypertrophy by activating protein kinase A and C through β- and α
1
-adrenoceptors, respectively, protein kinase A has been reported to inhibit cell growth in many other cell types.

Methods and Results
To elucidate the molecular mechanism of norepinephrine-induced hypertrophic responses, we examined the effects of protein kinase A and protein kinase C on the activities of
raf
-1 kinase and mitogen-activated protein (MAP) kinases and on protein synthesis rates using cultured cardiomyocytes of neonatal rats. Norepinephrine-induced activation of MAP kinases was partially inhibited by either an α
1
-adrenoceptor blocker (prazosin) or a β-adrenoceptor blocker (propranolol) and was completely abolished by both blockers. Both a β-adrenoceptor agonist, isoproterenol, and an α
1
-adrenoceptor agonist, phenylephrine, increased the activities of
raf
-1 kinase and MAP kinases and phenylalanine incorporation into proteins. Furthermore, isoproterenol and phenylephrine synergistically activated these kinases and protein synthesis. Similar synergistic activation of MAP kinases was observed when other protein kinase A–activating agents such as forskolin, dibutyryl cAMP, and isobutylmethylxanthine were used with a protein kinase C–activating agent at the same time. Chelation of extracellular Ca
2+
completely abolished isoproterenol- and phenylephrine-evoked MAP kinase activation.

Conclusions
Norepinephrine activates the
raf
-1 kinase/MAP kinase cascade through both α
1
- and β-adrenergic stimulation, and signaling pathways from the two receptors synergistically induce cardiomyocyte hypertrophy.
Early Versus Delayed Angiotensin-Converting Enzyme Inhibition in Experimental Chronic Heart Failure
Authors: Mulder Paul , Devaux Bruno , Richard Vincent , Henry Jean-Paul , Wimart Marie-Catherine , Thibout Emmanuel , Mace´ Bertrand , Thuillez Christian
Published: June 2012

Background
The efficacy of ACE inhibitors in congestive heart failure (CHF) might be affected by the pathophysiological status present at the onset of treatment. We compared in a rat model the effects of ACE inhibition (lisinopril, 10 mg·kg
−1
·d
−1
) initiated early (1 week) or late (3 months) after myocardial infarction (ie, at time points corresponding to moderate or severe CHF without or with established cardiac remodeling).

Methods and Results
Survival was improved by early treatment at 3 months (from 76% to 95%) and by both early and delayed treatment at 9 months (placebo, 28%; early, 90%; delayed, 61%). Delayed treatment was initiated in a more severe pathophysiological context of CHF than early treatment, illustrated in untreated rats by higher left ventricular (LV) end-diastolic and central venous pressures and by increased LV weight and LV cavity circumference. After 9 months, early and delayed treatments reduced systolic, LV end-diastolic, and central venous pressures. Both treatments also similarly decreased LV weight, LV cavity circumference, and LV collagen density.

Conclusions
In this rat model of CHF, early and delayed ACE inhibitor treatments both increase survival and exert similar beneficial effects on cardiac hemodynamics and remodeling. Although early treatment prevents the development of ventricular dysfunction and remodeling, delayed treatment is capable of reversing cardiac hypertrophy and remodeling, as well as ventricular dysfunction. Thus, ACE inhibitors exert marked beneficial effects even when treatment is initiated late into the evolution of heart failure (ie, at a time of established ventricular dysfunction and remodeling).
Septal Function During Left Ventricular Unloading
Authors: Moon Marc R. , Bolger Ann F. , DeAnda Abe , Komeda Masashi , Daughters George T. , Nikolic Srdjan D. , Miller D. Craig , Ingels Neil B.
Published: June 2012

Background
Left ventricular (LV) unloading with mechanical support devices alters biventricular geometry and impairs right ventricular (RV) contractility, but its effect on septal systolic function remains unknown.

Methods and Results
To evaluate the effects of LV volume and pressure unloading on septal geometry and function, LV preload was abruptly reduced by clamping left atrial pressure between 0 and −2 mm Hg in seven open-chest, anesthetized dogs by use of a pressure-control servomechanism to withdraw blood from the left atrium. With left atrial pressure clamping, maximal LV pressure decreased 30±12% (mean±SD) (
P
<.0001) and LV end-diastolic cross-sectional area (determined by two-dimensional echocardiography) decreased by 53±16% (
P
<.0001). This caused the septum to shift toward the left (RV septal free-wall dimension increased;
P
<.004) and flatten (radius of curvature increased;
P
<.0002), while LV septal free-wall dimension fell (
P
<.0001). Septal end-diastolic thickness increased 23±15% (
P
<.0005), reflecting a decline in septal preload. Systolic septal thickening decreased (
P
<.002), while systolic septal output (Septal Output=Septal Thickening×Heart Rate) fell from 30±17 to 15±22 cm/min (
P
<.002). This was associated with movement along the septal Frank-Starling equivalent (septal output versus end-diastolic septal thickness [preload] relation) to a less productive portion of the curve.

Conclusions
LV unloading not only altered interventricular septal geometry but also reduced septal systolic thickening and output, all of which may contribute to impaired RV contractility during mechanical LV support.
Low-Density Lipoproteins Inhibit the Na
+
/H
+
Antiport in Human Platelets
Authors: Nofer Jerzy-Roch , Tepel Martin , Kehrel Beate , Wierwille Sonja , Walter Michael , Seedorf Udo , Zidek Walter , Assmann Gerd
Published: June 2012

Background
LDL have been reported to augment platelet activation, and increased platelet reactivity has been observed in familial hypercholesterolemia. However, the underlying mechanism of this putatively atherogenic effect is unknown. Because intracellular pH (pH
i
) may play an important role in platelet function, we examined the influence of LDL on pH
i
and Na
+
/H
+
antiport activity in human platelets and compared it with the effect of [3-methylsulfonyl-4-piperidinobenzoyl] guanidine hydrochloride (HOE 694), a selective Na
+
/H
+
antiport inhibitor.

Methods and Results
Using a fluorescent dye technique, we demonstrated that incubation of platelets with physiological concentrations of LDL or with HOE 694 decreased pH
i
. In addition, both LDL and HOE 694 inhibited the Na
+
/H
+
antiport in platelets treated with sodium propionate or thrombin. The inhibitory effect of LDL was observed both in normal and in glycoprotein (GP)IIb/IIIa- as well as in GPIIIb (CD36)-deficient platelets and was not influenced by the covalent modification of apolipoprotein B lysine residues, suggesting that specific LDL binding sites were not involved. Thrombin-induced phosphoinositide breakdown, diacylglycerol formation, and Ca
2+
mobilization, as well as platelet aggregation and granule secretion, were potentiated by both LDL and HOE 694. pH
i
and Na
+
/H
+
antiport activity were significantly reduced in platelets from patients with familial hypercholesterolemia. Both parameters were normalized after normalization of LDL levels by apheresis treatment.

Conclusions
LDL inhibits the Na
+
/H
+
antiport most likely via receptor-independent mechanisms, thereby augmenting platelet reactivity. This novel mechanism explains increased platelet reactivity in patients with familial hypercholesterolemia and may contribute to the atherogenic potential of LDL.
Internal Atrial Defibrillation in Humans
Authors: Cooper Randolph A. S. , Johnson Eric E. , Wharton J. Marcus
Published: June 2012

Background
The optimal waveform for internal atrial defibrillation (IAD) in humans is unknown. This study tested the effect of waveform duration and phase duration on the efficacy of biphasic waveforms for IAD.

Methods and Results
Electrodes were positioned in the right atrial appendage and coronary sinus in 13 patients. In part 1, the atrial defibrillation thresholds (ADFTs) for 5 monophasic waveforms (2, 4, 6, 10, and 20 ms) and 5 symmetrical biphasic waveforms (1/1, 2/2, 3/3, 5/5, and 10/10 ms) were compared in 6 patients. In part 2, the ADFTs for two asymmetrical biphasic waveforms (7.5/2.5 and 2.5/7.5 ms) were compared with those for a symmetrical biphasic waveform (5/5 ms) and a monophasic waveform (10 ms) in 7 patients. In part 1, biphasics with total durations of 4 to 20 ms had significantly lower ADFTs than monophasic waveforms of the same total duration. For a total duration of 2 ms, there was no significant difference in ADFTs between the biphasic and the monophasic waveforms. There was no difference between symmetrical biphasic waveforms of 4 to 20 ms. In part 2, the 7.5/2.5 ms asymmetrical biphasic had significantly lower ADFTs than the three other waveforms tested. Both the 7.5/2.5 ms asymmetrical and the 5/5 ms symmetrical biphasic waveform had significantly lower ADFTs than the 2.5/7.5 ms asymmetrical biphasic and the 10 ms monophasic waveforms.

Conclusions
For IAD in humans, biphasic waveforms were more efficacious than monophasic waveforms. This improved efficacy is related to the total duration of the biphasic waveform and each individual phase duration of the biphasic waveform.
Very Early Noninvasive Detection of Acute Experimental Nonreperfused Myocardial Infarction With
99m
Tc-Labeled Glucarate
Authors: Narula Jagat , Petrov Artiom , Pak Koon-Yan , Lister Bradford C. , Khaw Ban-An
Published: June 2012

Background
99m
Tc glucarate has recently been reported to be an infarct-avid agent. The feasibility of imaging with
99m
Tc glucarate was evaluated for the early diagnosis of nonreperfused and reperfused myocardial infarction and compared with localization of simultaneously administered
111
In anti-myosin.

Methods and Results
Four groups of six rabbits each were studied. The left anterior descending coronary artery (LAD) was kept persistently occluded (n=6) or reperfused after 40 minutes (n=6) in rabbits. After confirmation of LAD occlusion by
201
Tl scintigraphy, a mixture of
99m
Tc glucarate (15.7±1.6 mCi) and
111
In anti-myosin (0.53±0.03 mCi) was administered intravenously. Another group of rabbits (n=6) with 5 or 15 minutes of LAD occlusion were used to assess the affinity of
99m
Tc glucarate for the ischemic myocardium. The remaining 6 rabbits with reperfused myocardial infarction were used for the assessment of subcellular localization of
99m
Tc glucarate.
99m
Tc glucarate cleared rapidly from circulation (elimination t
1/2
, 36 minutes). Infarcts were visualized within 10 minutes in reperfused and within 30 minutes in nonreperfused coronary territories after intravenous administration.
111
In anti-myosin delineated reperfused infarcts within 1 to 3 hours, but no uptake was seen in persistently occluded rabbits.
99m
Tc glucarate uptake in reperfused and nonreperfused infarct centers was 28 and 12 times greater, respectively, than that in normal myocardium (
P
=.0001). A direct correlation between glucarate and anti-myosin localization (
r
=.60 for nonreperfused; 0.76 for reperfused;
P
<.0001) was observed. Ischemic hearts showed no glucarate uptake. Subcellularly,
99m
Tc glucarate localized predominantly in the nuclear fraction of the infarct, with lesser extents in the mitochondrial and cytoplasmic fractions.

Conclusions
Noninvasive imaging of myocardial infarcts with
99m
Tc glucarate is possible within minutes in persistently occluded or reperfused myocardial infarcts. Early detectability results from the rapid blood clearance and high avidity of glucarate for the acutely necrotic myocardial tissue.
Premorbid Determinants of Left Ventricular Dysfunction in a Novel Model of Gradually Induced Pressure Overload in the Adult Canine
Authors: Koide Masaaki , Nagatsu Masayoshi , Zile Michael R. , Hamawaki Masayoshi , Swindle M. Michael , Keech George , DeFreyte Gilberto , Tagawa Hirofumi , Cooper George , Carabello Blase A.
Published: June 2012

Background
When a pressure overload is placed on the left ventricle, some patients develop relatively modest hypertrophy whereas others develop extensive hypertrophy. Likewise, the occurrence of contractile dysfunction also is variable. The cause of this heterogeneity is not well understood.

Methods and Results
We recently developed a model of gradual proximal aortic constriction in the adult canine that mimicked the heterogeneity of the hypertrophic response seen in humans. We hypothesized that differences in outcome were related to differences present before banding. Fifteen animals were studied initially. Ten developed left ventricular dysfunction (dys group). Five dogs maintained normal function (nl group). At baseline, the nl group had a lower mean systolic wall stress (96±9 kdyne/cm
2
; dys group, 156±7 kdyne/cm
2
;
P
<.0002) and greater relative left ventricular mass (left ventricular weight [g]/body wt [kg], 5.1±0.36; dys group, 3.9±0.26;
P
<.02). On the basis of differences in mean systolic wall stress at baseline, we predicted outcome in the next 28 dogs by using a cutoff of 115 kdyne/cm
2
. Eighteen of 20 dogs with baseline mean systolic stress >115 kdyne/cm
2
developed dysfunction whereas 6 of 8 dogs with resting stress ≤115 kdyne/cm
2
maintained normal function.

Conclusions
We conclude that this canine model mimicked the heterogeneous hypertrophic response seen in humans. In the group that eventually developed dysfunction there was less cardiac mass despite 60% higher wall stress at baseline, suggesting a different set point for regulating myocardial growth in the two groups.
A Novel Method for Nonfluoroscopic Catheter-Based Electroanatomical Mapping of the Heart
Authors: Gepstein Lior , Hayam Gal , Ben-Haim Shlomo A.
Published: June 2012

Background
Cardiac mapping is essential for understanding the mechanisms of arrhythmias and for directing curative procedures. A major limitation of the current methods is the inability to accurately relate local electrograms to their spatial orientation. The objective of this study was to present and test the accuracy of a new method for nonfluoroscopic, catheter-based, endocardial mapping.

Methods and Results
The method is based on using a new locatable catheter connected to an endocardial mapping and navigating system. The system uses magnetic technology to accurately determine the location and orientation of the catheter and simultaneously records the local electrogram from its tip. By sampling a plurality of endocardial sites, the system reconstructs the three-dimensional geometry of the chamber, with the electrophysiological information color-coded and superimposed on the anatomy. The accuracy of the system was tested in both in vitro and in vivo studies and was found to be highly reproducible (SD, 0.16±0.02 [mean±SEM] and 0.74±0.13 mm) and accurate (mean errors, 0.42±0.05 and 0.73±0.03 mm). In further studies, electroanatomical mapping of the cardiac chambers was performed in 34 pigs. Both the geometry and activation sequence were repeatable in all pigs.

Conclusions
The new mapping method is highly accurate and reproducible. The ability to combine electrophysiological and spatial information provides a unique tool for both research and clinical electrophysiology. Consequently, the main shortcomings of conventional mapping—namely, prolonged x-ray exposure, low spatial resolution, and the inability to accurately navigate to a predefined site—can all be overcome with this new method.