bluuebunny/crossref_metadata_2025_split huggingface dataset:
"Intramural" residual interventricular defects after repair of conotruncal malformations.
Authors: Preminger T J , Sanders S P , van der Velde M E , Castañeda A R , Lock J E 
Published: June 2012

BACKGROUND
We report an unusual type of residual interventricular communication in patients with conotruncal malformations in which the aorta is completely or partly aligned with the right ventricle (RV). Interventricular communications after surgical repair usually result from additional defects, patch dehiscence, or incomplete closure and lie in the septal plane. However, after a right ventricular aorta is baffled to the left ventricle, the ventricular septal defect (VSD) patch and RV free wall form part of the systemic outflow tract. This "neo-left ventricular" outflow tract may provide a location for residual interventricular communications out of the septal plane.

METHODS AND RESULTS
We reviewed echocardiographic, angiographic, and clinical records of patients who had one or more residual interventricular communications out of the plane of the ventricular septum after repair of a conotruncal anomaly. Between June 1990 and October 1992, we observed such defects in eight patients, 5 to 26 years old, after repair of double-outlet right ventricle (n = 6), tetralogy of Fallot (n = 1), or truncus arteriosus (n = 1). In each, the VSD patch was anchored to the RV free wall near the aortic root. Nonetheless, channels were observed around the edge of the patch, between the neo-systemic outflow tract and the right ventricle. All patients had right ventricular hypertension; in seven, the pulmonary-to-systemic flow ratio (Qp:Qs) was > or = 2. At multiple unsuccessful reoperations (two to four per patient), the patch edges appeared securely attached to myocardium. Angiographic views profiling the septum failed to localize these defects, since they are not in the native septum. Echocardiographic detection of such anterior defects can be difficult. Transcatheter umbrella closure was attempted in the seven patients with large shunts; success was limited by the multiplicity of flow channels. Umbrella closure eliminated the need for further reoperation in four of seven patients, one patient died suddenly awaiting reoperation, and two deaths followed reoperation.

CONCLUSIONS
"Intramural" residual interventricular defects are difficult to diagnose by all modalities. Umbrella placement may reduce the left-to-right shunt. Successful surgical closure may require removal and reattachment of the anterior portion of the patch.
Intravascular ultrasound of coronary arteries in children. Assessment of the wall morphology and the lumen after Kawasaki disease.
Authors: Sugimura T , Kato H , Inoue O , Fukuda T , Sato N , Ishii M , Takagi J , Akagi T , Maeno Y , Kawano T 
Published: June 2012

BACKGROUND
The long-term clinical issue in Kawasaki disease (KD) concerns the coronary artery lesion. Two-dimensional echocardiography and coronary angiography are routine examinations to evaluate the coronary lesions; however, these are not adequate to assess the wall morphology of the coronary artery (CA). Intravascular ultrasound imaging (IVUS), a new technology for the evaluation of the coronary artery lumen and wall morphology in vivo, was performed for patients after KD in their long-term follow-up, and we examined the new insights it gave.

METHODS AND RESULTS
IVUS was performed during cardiac catheterization in 20 subjects (10 patients after KD who still had coronary aneurysms or regressed coronary aneurysms, 2 after KD who had no coronary abnormal lesion, and 8 control patients with congenital heart disease and normal CA). We evaluated the wall structure at 10 to 15 sites of the CA in each patient. IVUS was performed with a commercially available ultrasound imaging catheter. Four sites of a CA aneurysm in KD demonstrated a markedly dilated lumen without thickened intima. One site of a CA aneurysm with calcification demonstrated an asymmetrical lumen by a dense echo with acoustic shadows. Twenty-two sites of a regressed CA aneurysm demonstrated a marked symmetrical or asymmetrical thickening of the intima with a dense echo, in which the size of the lumen was similar to that at a site near a regressed aneurysm. The sites of angiographically normal CA revealed normal structures and a thin intima in many instances. Nine of 28 sites in KD with a CA abnormal lesion, particularly near a coronary aneurysm or regressed aneurysm, demonstrated a mild thickening of the intima. All the 10 sites in KD without a CA abnormal lesion and all the 25 sites in patients with congenital heart disease with normal CA demonstrated a smooth intima.

CONCLUSIONS
This study demonstrated that the site of a regressed coronary aneurysm has a markedly thickened but smooth intima. The sites of angiographically normal CA after KD with or without a coronary lesion demonstrated normal IVUS findings in most instances but in some cases revealed a mild intimal thickening. IVUS is useful to evaluate the CA wall morphology and may contribute to the assessment of long-term CA sequelae and the possible development of arteriosclerotic changes in KD.
Increased vascular responsiveness to norepinephrine in rats with heart failure is endothelium dependent. Dissociation of basal and stimulated nitric oxide release.
Authors: Teerlink J R , Gray G A , Clozel M , Clozel J P 
Published: June 2012

BACKGROUND
Endothelial dysfunction and abnormal vascular responsiveness to vasoconstrictors may play an important role in chronic heart failure (CHF). The purpose of our study was to (1) evaluate whether the vascular response to norepinephrine is abnormal in a rat model of heart failure; (2) investigate the role of alpha 1- and alpha 2-adrenergic receptors; and (3) assess the contribution of the endothelium, and specifically endothelium-derived nitric oxide, to this response.

METHODS AND RESULTS
Concentration-response curves of rat thoracic aortic rings were studied in isolated organ baths at 1 week after coronary artery ligation. In CHF rats, norepinephrine-induced contractions were increased in intact rings compared with rings from sham rats, despite decreased contraction in denuded rings. Decreased alpha 1-receptor sensitivity was demonstrated by the increased EC50 of methoxamine in endothelium-denuded rings from CHF rats, although maximal responses to KCl contraction were also decreased in CHF. There was no difference in the vascular response to clonidine, and acetylcholine-mediated relaxations were preserved in CHF rats, suggesting normal stimulated nitric oxide release. However, nitric oxide synthase inhibition with N omega-nitro-L-arginine methyl ester, as well as measurements of basal cGMP, demonstrated that basal nitric oxide release was decreased in CHF rats.

CONCLUSIONS
This study demonstrates that the increased vascular responsiveness to norepinephrine in intact vessels from rats with heart failure is the result of decreased basal nitric oxide release and suggests that the dissociation of basal and stimulated nitric oxide release may play a pathophysiology role at an early stage of heart failure.
Interaction of acute ventricular dilatation and d-sotalol during sustained reentrant ventricular tachycardia around a fixed obstacle.
Authors: Reiter M J , Zetelaki Z , Kirchhof C J , Boersma L , Allessie M A 
Published: June 2012

BACKGROUND
Antiarrhythmic therapy of ventricular tachycardia is associated with decreased efficacy and increased proarrhythmia in patients with congestive heart failure, but the explanation for these observations is not known. This study examined the interaction of ventricular dilatation and d-sotalol in a model of reentry ventricular tachycardia.

METHODS AND RESULTS
Thin epicardial layers of anisotropic myocardium were created in Langendorff-perfused rabbit left ventricles by a cryo procedure. A fluid-filled, latex balloon was secured within the left ventricle to change ventricular volume. Sustained reentrant ventricular tachycardia, around a central cryolesion, was induced by rapid pacing in all preparations (n = 7). Epicardial mapping was performed through 248 electrodes. Single premature beats introduced within the reentry circuit were used to define the excitable gap. Dilatation did not influence ventricular tachycardia cycle length or conduction velocity. A 1.25-mL increase in left ventricular volume widened the excitable gap by 12% (range, 5% to 29%) (P < .001) because of a decrease in myocardial refractoriness. d-Sotalol (final concentration, 10 mg/L) narrowed the excitable gap 18% (range, 7% to 29%) (P = .002) in the undilated left ventricle. d-Sotalol was less effective in the dilated left ventricle, narrowing the excitable gap only 9%, a difference that was not statistically significant. During pacing to induce or terminate tachycardia, tachycardia acceleration was observed significantly more frequently in the dilated than in the undilated ventricle. Ventricular tachycardia acceleration was due to the development of double-wave reentry (two successive waves traveling in the same circuit in the same direction). d-Sotalol, which narrowed the excitable gap, prevented tachycardia acceleration and double-wave reentry.

CONCLUSIONS
Antiarrhythmic efficacy may be decreased by dilatation because of widening of the initial excitable gap and a decrease in the gap-narrowing effect of these agents. Double-wave reentry, more likely with a widening of excitable gap, may partially explain tachycardia acceleration in the dilated ventricle.
The impending crisis awaiting cardiac transplantation. Modeling a solution based on selection.
Authors: Stevenson L W , Warner S L , Steimle A E , Fonarow G C , Hamilton M A , Moriguchi J D , Kobashigawa J A , Tillisch J H , Drinkwater D C , Laks H 
Published: June 2012

BACKGROUND
Each month, the number of transplant candidates added to the waiting list exceeds the number of transplantations performed, and many outpatients deteriorate to require transplantation urgently. The current list of 2400 candidates and the average wait of 8 months continue to increase.

METHODS AND RESULTS
To determine the size at which the outpatient and critical candidate pools will stabilize, population models were constructed using current statistics for donor hearts, candidate listing, sudden death, and outpatient decline to urgent status and revised to predict the impact of alterations in policies of candidate listing. If current practices continue, within 48 months the predicted list will stabilize as the sum of an estimated 270 hospitalized candidates, among whom, together with newly listed urgent candidates, all hearts will be distributed and 3700 outpatient candidates with virtually no chance of transplantation unless they deteriorate to an urgent status. Decreasing the upper age limit now to 55 years would reduce the number listed each month by 30% and result within 48 months in a list of only 1490. The list could also be decreased by 30%, however, if it were possible to list only a candidate group with an 80% chance (compared with 52% estimated currently) of sudden death or deterioration during the next year. With this strategy, the waiting list would equilibrate within 48 months to one-third the current size, with 50% of hearts for outpatient candidates, who would then have an 11% chance each month of receiving a heart compared with 0% if recent policies prevail. Total deaths, with and without transplantation, would be minimized by this rigorous selection of outpatient candidates.

CONCLUSIONS
This study implies that immediate provisions should be made to limit candidate listing and revise expectations to reflect the diminishing likelihood of transplantation for outpatient candidates. Future emphasis should be on improved selection of candidates at highest risk without transplantation.
Oral verapamil inhibits platelet thrombus formation in humans.
Authors: L-Lacoste L , Lam J Y , Hung J , Waters D 
Published: June 2012

BACKGROUND
Calcium antagonists such as verapamil are potent coronary and systemic vasodilators that are used in the treatment of coronary disease. They have also been shown to inhibit platelet aggregation in vitro, but whether they have beneficial antithrombotic effects in humans is unclear, and whether they can potentiate the antithrombotic effects of aspirin is unknown.

METHODS AND RESULTS
Platelet thrombus formation and whole blood platelet aggregation were measured in 18 stable coronary patients on three separate occasions: at baseline when receiving no active medications, after 7 days of receiving oral verapamil SR (240 mg/d), and after 7 days of receiving a combination of oral verapamil SR and aspirin (325 mg/d). Thrombus formation on porcine aortic media that were placed into cylindrical flow chambers and exposed to flowing antecubital venous blood for 3 minutes was assessed morphometrically at a shear rate of 2546 s-1, which is typical of arterial flow at sites of stenoses. Thrombus formation under basal conditions was 7.0 +/- 1.6 microns 2, and this was decreased to 3.1 +/- 0.5 microns 2 (P < .05) after 7 days of treatment with oral verapamil SR and to 2.6 +/- 0.5 microns 2 (P < .05) after 7 days of treatment with oral verapamil and aspirin. Whole blood platelet aggregation levels in response to 0.050 and 0.075 U of thrombin at baseline were 10.8 +/- 1.0 and 11.9 +/- 1.0 omega; aggregation was inhibited after 7 days of treatment with verapamil to 6.5 +/- 1.1 and 7.8 +/- 0.9 omega (P < .05 versus baseline) and after 7 days of treatment with verapamil and aspirin to 6.1 +/- 1.1 and 7.2 +/- 1.0 omega (P < .05), respectively.

CONCLUSIONS
The present study demonstrates that part of the benefit of verapamil in ischemic heart disease may occur by inhibition of platelet aggregation and thrombus formation. This beneficial antithrombotic effect may be important in preventing acute coronary ischemic events resulting from thrombus formation at sites of plaque rupture.
A prospective study of the health effects of alcohol consumption in middle-aged and elderly men. The Honolulu Heart Program.
Authors: Goldberg R J , Burchfiel C M , Reed D M , Wergowske G , Chiu D 
Published: June 2012

BACKGROUND
The study objective was to determine the association between reported alcohol consumption and total mortality, mortality from selected causes, and incident nonfatal chronic disease events in middle-aged (51 to 64 years old) and elderly (65 to 75 years old) men during an approximate 15-year follow-up period.

METHODS AND RESULTS
We conducted a prospective epidemiological study of Japanese-American men who were participating in the Honolulu Heart Program and were free from coronary heart disease, cerebrovascular disease, and cancer at baseline examination and at subsequent reexamination 6 years later. Self-reported alcohol consumption was determined twice: at the baseline examination in 1965 through 1968 and at reexamination approximately 6 years later (1971 through 1974). Four primary alcohol consumption groups who reported similar alcohol intake at the time of these two clinical examinations were considered: abstainers and light (1 to 14 mL of alcohol per day), moderate (15 to 39 mL of alcohol per day), and heavy (> or = 40 mL of alcohol per day) drinkers. Study end points were also determined in very light (1 to 4.9 mL of alcohol per day) drinkers and in men who reported a change in their alcohol intake between examinations. Longitudinal follow-up was carried out through the end of 1988 with determination of selected fatal and nonfatal events according to alcohol intake. After controlling for several potentially confounding factors, total mortality exhibited a J-shaped pattern in relation to alcohol consumption in middle-aged and elderly men. There was a trend for lower rates of occurrence of combined fatal and nonfatal coronary heart disease events with increasing alcohol consumption in both middle-aged and elderly men. Increasing alcohol consumption was related to an increased risk of fatal and nonfatal strokes in middle-aged men, whereas elderly light and moderate drinkers were at increased risk for fatal and nonfatal strokes. Heavy drinkers were at increased risk for fatal and nonfatal malignant neoplasms in the two age groups examined.

CONCLUSIONS
The results of this long-term prospective study provide a balanced perspective of the health effects of alcohol consumption in middle-aged and elderly men. High levels of alcohol consumption were shown to be related to an increasing risk of diseases of considerable public health importance. These findings suggest that caution be taken in formulating population-wide recommendations for increases in the population levels of alcohol consumed given the associated significant social and biological problems of high consumption levels.
Identification of coronary artery stenoses and poststenotic blood flow patterns using a miniature high-frequency epicardial transducer.
Authors: Kenny A , Shapiro L M 
Published: June 2012

BACKGROUND
Intraoperative epicardial coronary Doppler ultrasound has the potential to provide anatomic and functional information. This technique has been hindered by the large size of standard transducers, but a miniature transducer is available that may fulfill the potential of coronary ultrasound.

METHODS AND RESULTS
Twenty consecutive patients who were undergoing coronary artery bypass grafting were studied and compared with 9 control patients with normal coronary arteries who were undergoing routine mitral valve surgery. A miniature 6.5-MHz transducer was used to image coronary arteries and measure coronary blood flow velocities. Seventeen proximal left anterior descending and 3 right coronary artery stenoses were studied. As defined by coronary angiography (1 to 34 days before surgery), there were 13 severe stenoses (> 70%), 4 moderate stenoses (40% to 70%), 2 minor stenoses (< 40%), and 1 subtotal occlusion. Stenoses were readily identified by ultrasound. Color flow mapping demonstrated laminar flow in normal arteries and nonlaminar flow across moderate and severe stenoses. In the control patients with unobstructed arteries, peak and mean diastolic velocities were 35 +/- 2.1 and 26 +/- 1.9 cm/s with peak and mean systolic velocities of 16 +/- 1.4 and 11 +/- 0.8 cm/s, respectively. Prestenotic flow velocities were not significantly different from normal control values, but a wide range of poststenotic flow disturbances were detected. Analysis of the 20 study patients did not reveal significant differences in poststenotic compared with prestenotic flow. A subgroup analysis of 12 patients with severe left anterior descending coronary artery stenoses was performed, and reversed poststenotic systolic flow was seen in 9. Prestenotic peak and mean systolic velocities were 16.5 +/- 1.7 and 11.9 +/- 1.1 cm/s, respectively, and were significantly altered downstream of the stenoses at -22.7 +/- 17.2 and -15.9 +/- 10.9 cm/s (P < .05 and P < .01, respectively). Reversed systolic flow was seen only distal to severe left anterior descending coronary artery stenoses and did not correlate with retrograde collateral filling as determined by preoperative coronary angiography. Moderate stenoses appeared to increase both systolic and diastolic components of poststenotic flow.

CONCLUSIONS
Epicardial Doppler ultrasound with a miniature transducer identifies coronary stenoses and associated blood flow disturbances. Compared with moderate lesions, severe stenoses demonstrated different poststenotic flow patterns. Intraoperative use of this technique may determine the hemodynamic significance of coronary stenoses.
Chronic dynamic exercise improves a functional abnormality of the G stimulatory protein in cardiomyopathic BIO 53.58 Syrian hamsters.
Authors: Tomita T , Murakami T , Iwase T , Nagai K , Fujita J , Sasayama S 
Published: June 2012

BACKGROUND
The effects of chronic exercise training on myocardial contractility and beta-adrenergic signal transduction in hearts with left ventricular dysfunction have not been determined.

METHODS AND RESULTS
Fourteen-week-old cardiomyopathic BIO 53.58 and normal F1B Syrian hamsters underwent 10 weeks of treadmill training and were compared with 24-week-old BIO 53.58 and F1B untrained controls. Left ventricular isovolumic maximum positive dP/dt and peak developed pressure were significantly lower in BIO 53.58 than in F1B controls. Exercise training improved left ventricular contractile indices in BIO 53.58 but not F1B hamsters. The left ventricular beta-adrenergic receptor number (Bmax) was similar in BIO 53.58 and F1B controls. Basal adenylate cyclase activity (ACA) and ACAs stimulated by isoproterenol, 5'-guanylylimidodiphosphate (GppNHp), sodium fluoride, and forskolin were significantly lower in BIO 53.58 than in F1B controls. The functional activity of stimulatory guanine nucleotide-binding protein (Gs), as determined by reconstitution with S49 lymphoma cyc- cell membranes, was significantly lower in BIO 53.58 controls. After 10 weeks of exercise training, Bmax and basal and isoproterenol-stimulated ACAs were unchanged in either BIO 53.58 or F1B hamsters compared with controls. However, in F1B hamsters, training decreased ACAs stimulated by GppNHp, sodium fluoride, and forskolin, with a reduced functional activity of Gs. In contrast, these ACAs increased significantly in association with an enhanced Gs activity in cardiomyopathic BIO 53.58 hamsters after training.

CONCLUSIONS
Chronic exercise training does not change receptor-mediated beta-adrenergic responsiveness in either F1B or BIO 53.58 hamsters. However, exercise training reduces Gs activity in normal F1B hamsters and improves the functional abnormality of Gs in cardiomyopathic BIO 53.58 hamsters. This improvement may potentially contribute to augmented left ventricular contractility in BIO 53.58 after training.
Mapping of reset of anatomic and functional reentry in anisotropic rabbit ventricular myocardium.
Authors: Boersma L , Brugada J , Kirchhof C , Allessie M 
Published: June 2012

BACKGROUND
Premature stimulation is used to characterize the reentrant circuit during ventricular tachycardia (VT) in patients. The goal of this study was to compare the effects of premature stimulation on functional and anatomic reentrant VT.

METHODS AND RESULTS
In 18 Langendorff-perfused rabbit hearts, thin layers of anisotropic left ventricular subepicardium were created by a cryoprocedure. In 8 hearts, rapid pacing induced reentry around a line of functional conduction block; in 10 hearts, reentry occurred around a fixed epicardial obstacle created by a cryoprobe. The cycle lengths (CL) of functional and anatomic VT were 110 +/- 10 and 167 +/- 17 milliseconds, respectively. During anatomic VT, the excitable gap measured 43% of the CL and premature stimuli could always reset VT (44 +/- 12 milliseconds). During early premature beats, conduction of the orthodromic wave was slightly depressed, but anatomic VT was never terminated. Reset curves at different sites in the ventricle revealed three different response types, both determined by and characterizing the spatial and temporal relation between pacing and recording sites. Premature stimulation during functional VT revealed a local excitable gap at the pacing site measuring 27% of the cycle length of VT. However, in only 3 of 8 hearts, premature stimuli could reset functional VT by 8%. In 5 VTs, advancement of the paced activation was fully compensated by prolongation of the return cycle, and VT was not reset. Due to slow conduction both toward and inside the circuit, the paced orthodromic wave lost its prematurity already within a distance of 6 to 10 mm from the pacing site.

CONCLUSIONS
Both during anatomic and functional reentry, an excitable gap is present in the reentrant circuit. Three different response curves reveal the localization of the pacing and recording sites in the circuit. Anatomic VT can always be reset by premature stimuli, whereas in 5 of 8 hearts, functional VT could not be reset. In the other 3 hearts, VT could only be reset for less than 7% to 11% of the VT interval. Therefore, it seems very unlikely that clinical VT based on functional reentry can be reset.