bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracoronary thrombus formation causes focal vasoconstriction of epicardial arteries in patients with coronary artery disease.
Authors: Zeiher A M , Schächinger V , Weitzel S H , Wollschläger H , Just H
Published: June 2012

BACKGROUND

Experimental studies have demonstrated that intracoronary platelet aggregation and thrombus formation may induce marked vasoconstriction of epicardial arteries with endothelial injury.

METHODS AND RESULTS

To examine the effects of intracoronary thrombus formation on coronary vasomotor tone of human epicardial arteries in vivo, we studied 15 patients who developed intracoronary thrombi adherent to the guide wire during balloon dilatation. Epicardial artery luminal area was evaluated by quantitative coronary angiography proximal and distal to the site of intracoronary thrombus formation and in a reference vessel before and after thrombus formation as well as after intracoronary injection of 0.2-0.3 mg nitroglycerin. All artery segments distal to the site of thrombus formation showed vasoconstriction with a luminal area reduction of -27.4 +/- 17.1% (p less than 0.001), whereas proximal vessel segments and reference vessels not manipulated during percutaneous transluminal coronary angioplasty did not demonstrate any significant luminal area changes during thrombus formation. Angiographic measurements after advancing the guide wire with the adherent thrombus (performed in six of the 15 patients) revealed in all patients that vasoconstriction did develop at a new site distal to the thrombus persistence of the initial vasoconstriction now residing proximal to the thrombus. Thus, there was a sequential association between thrombus formation and subsequent distal vasoconstriction. Intracoronary injection of nitroglycerin abolished the thrombus-induced vasoconstriction. No significant luminal area changes were observed in 20 patients without angiographic evidence of intracoronary thrombus formation.

CONCLUSIONS

Intracoronary thrombus formation during percutaneous transluminal coronary angioplasty causes focal vasoconstriction of epicardial arteries in patients with coronary artery disease. Although caution must be advised in the extrapolation of this phenomenon, which was observed in a manipulated artery during coronary angioplasty, the vasoconstrictor response to intracoronary thrombus formation in vivo may play an important role in the dynamic mechanisms of acute coronary heart disease syndromes.
Immediate postoperative aspirin improves vein graft patency early and late after coronary artery bypass graft surgery. A placebo-controlled, randomized study.
Authors: Gavaghan T P , Gebski V , Baron D W
Published: June 2012

BACKGROUND

The efficacy of aspirin for prevention of thrombotic graft occlusion after coronary artery bypass grafting (CABG) depends both on the dosage and time window of administration. Early and late graft patency were therefore assessed in a prospective, double-blind, randomized, placebo-controlled trial of aspirin, 324 mg daily, given within 1 hour of CABG.

METHODS AND RESULTS

Angiographic graft patency was determined at 1 week (231 patients) and 1 year (219 patients) after CABG. The early vein graft occlusion rate was 1.6% on aspirin and 6.2% on placebo (p = 0.004), and late graft occlusion rate was 5.8% on continued aspirin and 11.6% on placebo (p = 0.01). New graft occlusion between 1 week and 1 year was less common in patients on aspirin than on placebo (4.3% versus 7.4%, p = 0.013). The protective effect of aspirin against occlusion persisted in most subgroups of graft type, graft flow, diameter of recipient artery, location of grafted artery, and endarterectomy. Mean chest tube blood loss for the first 24 hours was 571 ml for the aspirin group and 563 ml for the placebo group. Red cell transfusion requirements were 902 ml in the aspirin group and 934 ml in the placebo group (p = NS). The reoperation rate was 4.8% in the aspirin group and 1% in the placebo group (p = 0.1).

CONCLUSIONS

Immediate postoperative administration of aspirin (324 mg) improves early graft patency and, with continued usage, protects against further occlusion up to 1 year after CABG. Postoperative blood loss was similar in the two groups; however, aspirin was associated with a nonsignificant higher rate of reoperation.
Functional role of the epicardium in postinfarction ventricular tachycardia. Observations derived from computerized epicardial activation mapping, entrainment, and epicardial laser photoablation.
Authors: Littmann L , Svenson R H , Gallagher J J , Selle J G , Zimmern S H , Fedor J M , Colavita P G
Published: June 2012

BACKGROUND

Conventionally, monomorphic sustained ventricular tachycardia in patients with remote myocardial infarction is believed to originate from the subendocardium. In a previous study, we demonstrated that electrical activation patterns during ventricular tachycardia occasionally suggest a subepicardial rather than subendocardial reentry.

METHODS AND RESULTS

This study prospectively evaluated the functional role of the epicardium in postinfarction ventricular tachycardia with complex intraoperative techniques including computerized electrical activation mapping, entrainment, observation of changes in activation pattern during successful epicardial laser photoblation, and histological study. Five of 10 consecutive patients undergoing intraoperative computerized activation mapping had 10 ventricular tachycardia morphologies displaying epicardial diastolic activation These 10 "epicardial" ventricular tachycardias revealed the following global activation patterns: monoregional spread (two), figure-eight activation (five), and circular macroreentry (three). Entrainment of ventricular tachycardia using epicardial stimulation was successfully performed from an area of slow diastolic conduction in four tachycardia morphologies. During entrainment, global activation remained undisturbed with recordings showing a long stimulus to QRS interval, unchanged QRS morphology, and pacing capture of all components of the reentry circuit. Neodymium:yttrium aluminum garnet laser photocoagulation was delivered during ventricular tachycardia to epicardial sites of presumed reentry. Epicardial photoablation terminated five of five figure-eight tachycardias, two of three circular macroreentry tachycardias but not the monoregional tachycardias. Electrophysiological recordings during epicardial laser photocoagulation demonstrated progressive prolongation of ventricular tachycardia cycle length and apparent interruption of the presumed reentrant circuit. Histological evaluation of the reentrant region (three patients) showed a rim of surviving myocardium under the epicardial surface.

CONCLUSIONS

This study suggests that 1) chronic postinfarction ventricular tachycardia may result from subepicardial macroreentry, 2) slow conduction within the reentry circuit can be localized by computerized mapping and epicardial entrainment, and 3) ventricular tachycardia interruption by laser photocoagulation results from conduction delay and block within critical elements of the reentrant pathway. Viable subepicardial muscle fibers may constitute the underlying pathology.
Endothelin has biological actions at pathophysiological concentrations.
Authors: Lerman A , Hildebrand F L , Aarhus L L , Burnett J C
Published: June 2012

BACKGROUND

Endothelin is an endothelium-derived peptide that produces sustained contraction of arterial and venous smooth muscle in vitro. Several studies have established endothelin as a systemic, renal, and coronary vasoconstrictor in vivo at pharmacological concentrations. Such concentrations of endothelin were antinatriuretic in association with activation of the renin-angiotensin-aldosterone system. Recent studies have demonstrated that endothelin is present in the plasma and that its plasma concentrations are increased in various pathological states associated with systemic and renal vasoconstriction. To date, it remains unclear if such increases in circulating endothelin are associated with biological activity. Thus, the objective of this study was to determine the biological action of endothelin on cardiorenal and endocrine function through administration of exogenous endothelin, which achieves plasma concentrations that have been reported in various pathophysiological conditions.

METHODS AND RESULTS

Experiments were conducted in two groups of anesthetized dogs. In group 1, endothelin-1 was infused intravenously at 2.5 ng/kg/ml (n = 6), which produced a doubling of circulating concentrations. Group 2 (n = 8) received saline vehicle to serve as a time control. The current studies demonstrate that a twofold increase in plasma endothelin concentrations did not affect mean blood pressure or coronary blood flow. Heart rate and cardiac output decreased in association with increased renal and systemic vascular resistances and antinatriuresis.

CONCLUSIONS

The present studies demonstrate that endothelin at pathophysiological plasma concentrations produced by exogenous endothelin has biological action. These studies support a functional role for endogenous endothelin as a potentially pathophysiological vasoconstrictor peptide hormone in the regulation of cardiovascular, renal, and endocrine function.
Pathogenesis of edema in constrictive pericarditis. Studies of body water and sodium, renal function, hemodynamics, and plasma hormones before and after pericardiectomy.
Authors: Anand I S , Ferrari R , Kalra G S , Wahi P L , Poole-Wilson P A , Harris P C
Published: June 2012

BACKGROUND

The pathogenesis of sodium and water accumulation in chronic constrictive pericarditis is not well understood and may differ from that in patients with chronic congestive heart failure due to myocardial disease. This study was undertaken to investigate some of the mechanisms.

METHODS AND RESULTS

Using standard techniques, the hemodynamics, water and electrolyte spaces, renal function, and plasma concentrations of hormones were measured in 16 patients with untreated constrictive pericarditis and were measured again in eight patients after pericardiectomy. The average hemodynamic measurements were as follows: cardiac output, 1.98 l/min/m2; right atrial pressure, 22.9 mm Hg; pulmonary wedge pressure, 24.2 mm Hg; and mean pulmonary artery pressure 30.2 mm Hg. The systemic and pulmonary vascular resistances (36.3 +/- 2.5 and 3.2 +/- 0.3 mm Hg.min.m2/l, respectively) were increased. Significant increases occurred in total body water (36%), extracellular volume (81%), plasma volume (53%), and exchangeable sodium (63%). The renal plasma flow was only moderately decreased (49%), and the glomerular filtration rate was normal. Significant increases also occurred in plasma concentrations of norepinephrine (3.6 times normal), renin activity (7.2 time normal), aldosterone (3.4 times normal), cortisol (1.4 times normal), growth hormone (21.8 times normal), and atrial natriuretic peptide (5 times normal). The ratio of left atrial to aortic diameter measured by echocardiography was only minimally increased (1.29 +/- 0.04), indicating that in constrictive pericarditis the atria are prevented from expanding. The studies repeated after pericardiectomy in the eight patients showed that all measurements returned toward normal.

CONCLUSIONS

The restricted distensibility of the atria, in constrictive pericarditis, limits the secretion of atrial natriuretic factor and, thus, reduces its natriuretic and diuretic effects. This results in retention of water and sodium greater than that occurring in patients with edema from myocardial disease. The arterial pressure is maintained more by the expansion of the blood volume than by an increase in the peripheral vascular resistance.
Value and limitations of transesophageal echocardiography in assessment of mitral valve prostheses.
Authors: Khandheria B K , Seward J B , Oh J K , Freeman W K , Nichols B A , Sinak L J , Miller F A , Tajik A J
Published: June 2012

BACKGROUND

Transthoracic Doppler echocardiography examination has become an integral part of the investigations performed in patients with mitral valve prostheses. The limitations of the transthoracic approach are well documented. Transesophageal echocardiography provides a unique window for achieving a clear view of the mitral prosthesis.

METHODS AND RESULTS

This study shows the usefulness of transesophageal echocardiography in clinical practice for assessment of patients with a mitral valve prosthesis. This technique demonstrated an abnormality in 48% of patients who had normal results on transthoracic examination. The overall sensitivity of transesophageal echocardiography was 96%.

CONCLUSIONS

Transesophageal echocardiography constitutes an essential part of a comprehensive two-dimensional/Doppler echocardiographic examination in patients with suspected malfunction of mitral prostheses.
Association of human leukocyte class II antigens with rheumatic fever or rheumatic heart disease in a Brazilian population.
Authors: Guilherme L , Weidebach W , Kiss M H , Snitcowsky R , Kalil J
Published: June 2012

BACKGROUND

The incidence of rheumatic heart disease is great in Brazil. We analyzed the distribution of human leukocyte (HLA) antigens in a Brazilian population sample with rheumatic fever or rheumatic heart disease, with the aim of better understanding the mechanisms involved.

METHODS AND RESULTS

HLA class I (A, B, and C) and class II (DR and DQ) antigen distribution was studied in 40 patients with diagnosis of rheumatic fever or rheumatic heart disease and compared with a control group of 617 healthy individuals for class I typing, from which 118 were drawn for class II typing. A strong correlation between rheumatic fever and rheumatic heart disease and HLA-DRw53 (72.9% in the disease group versus 39% in the control group: p = 0.00061, relative risk, 4.2; etiologic fraction, 0.43) was found. We also found an increase in the frequency of HLA-DR7 (57.5% in the disease group versus 26.3% in control group: p = 0.00715; relative risk, 3.8; etiologic fraction, 0.56). HLA class I and HLA-DQ typing did not point to any association with these diseases.

CONCLUSIONS

HLA-DR7 and HLA-DRw53 are markers for susceptibility to rheumatic fever and rheumatic heart disease in Brazil. These results could be explained by genetic differences resulting from racial or geographical diversity.
Coronary vasoconstriction induced by vasopressin. Production of myocardial ischemia in dogs by constriction of nondiseased small vessels.
Authors: Maturi M F , Martin S E , Markle D , Maxwell M , Burruss C R , Speir E , Greene R , Ro Y M , Vitale D , Green M V
Published: June 2012

BACKGROUND

We studied the effect of intracoronary administration of arginine-8-vasopressin on blood flow in nondiseased coronary arteries and determined whether this vasoconstriction was severe enough to produce ischemia in 30 dogs.

METHODS AND RESULTS

In group 1 (n = 6), after vasopressin administration coronary blood flow was decreased by 41% (p less than 0.002) without changes in heart rate or aortic pressure, and left ventricular ejection fraction measured by radionuclide angiocardiography was decreased by 18% (p less than 0.0005). In group 2 (n = 6), ischemia was confirmed by measurement of transmural pH changes. Administration of vasopressin decreased subendocardial pH of the infused zone from 7.40 +/- 0.03 to 7.31 +/- 0.07 (p less than 0.01). The subendocardial pH of the zone not infused with vasopressin did not change. To overcome the intrinsic regulation of blood flow, operating primarily in small coronary arteries, we hypothesized that vasopressin must increase resistance primarily in large rather than small coronary arteries. After intracoronary infusion in group 3 (n = 6), however, most (94%) of the increase in resistance during vasopressin administration was explained by an increase of resistance in small coronary arteries. In group 4 (n = 9), vasopressin decreased coronary blood flow by 50% and decreased local shortening by 90% at a time when systemic hemodynamics were unchanged. Coronary constriction induced by vasopressin, or the recovery from it, also was not altered by cyclooxygenase blockade.

CONCLUSIONS

Thus, vasopressin produces myocardial ischemia by constricting small, nondiseased coronary arteries severely enough to overcome the competition from normal coronary regulation, and this ischemic event is not mediated by prostaglandin products.
Electrogram patterns predictive of successful catheter ablation of accessory pathways. Value of unipolar recording mode.
Authors: Haïssaguerre M , Dartigues J F , Warin J F , Le Metayer P , Montserrat P , Salamon R
Published: June 2012

BACKGROUND

Transcatheter electrical ablation has been used in the treatment of arrhythmias, and most experience has been obtained by ablating the normal atrioventricular conduction system. Less information is available on ablation of atrioventricular accessory pathways.

METHODS AND RESULTS

Catheter ablation of overt accessory pathways was attempted in 135 patients with 142 distinct pathways, including 21 right parietal or anteroseptal, 47 posteroseptal, and 74 left lateral pathways. We sought to identify the type and value of electrophysiological parameters associated with successful ablation outcome. For this purpose, the unipolar recording mode was used in addition to bipolar anterograde and retrograde parameters. With a mean follow-up of 16 +/- 6 (mean +/- SD) months, fulguration was successful in eliminating preexcitation in 129 patients (96%), including all seven with two distinct accessory pathways. The first ablation attempt was successful in 110 patients, and two or more attempts were performed in 25 patients. Bipolar electrograms associated with success of fulguration showed a shorter atrioventricular conduction time (40 +/- 13 versus 53 +/- 17 msec, p less than 0.0001) and an earlier main ventricular deflection relative to delta wave onset (-1.7 +/- 10 versus 5 +/- 7 msec, p less than 0.001) than electrograms associated with unsuccessful outcome. The only parameter dealing with retrograde conduction (i.e., ventriculoatrial conduction time during reciprocating tachycardia) was not predictive (86 +/- 17 versus 93 +/- 17 msec). Neither was the atrial to ventricular electrogram amplitude ratio. Two unipolar parameters were found to be predictive of successful outcome: 1) The three different patterns PQS, P-QS, P-rS of unipolar waves recorded at the annulus were associated with respective success rates of 97%, 78%, and 55% (p less than 0.001). 2) Intrinsic deflection timing occurred -4 +/- 8 and 6 +/- 7 msec relative to delta wave onset in successful attempts and in failures, respectively (p less than 0.001). Logistic regression analysis revealed a single independent factor predictive of success, the unipolar pattern (p = 0.03), with an odds ratio of 7:1 (PQS pattern versus P-rS pattern). In the group of 18 patients who underwent a first unsuccessful but second successful attempt, comparison of electrograms revealed no difference in the ventriculoatrial conduction time but a significant improvement in anterograde parameters and unipolar pattern distribution.

CONCLUSIONS

Some distinctive electrogram patterns concerning anterograde conduction are associated with success of accessory pathway fulguration. The unfiltered unipolar recording mode (PQS pattern) contributes significantly to optimizing the accuracy of accessory pathway localization.
Coronary capillaries in patients with congestive cardiomyopathy or angina pectoris with patent main coronary arteries. Ultrastructural morphometry of endomyocardial biopsy samples.
Authors: Mosseri M , Schaper J , Admon D , Hasin Y , Gotsman M S , Sapoznikov D , Pickering J G , Yarom R
Published: June 2012

BACKGROUND

The coronary microvasculature may be abnormal even in the presence of angiographically normal epicardial arteries. Abnormalities of small coronary vessels have been invoked as a cause of angina.

METHODS AND RESULTS

To quantitatively evaluate the morphology of capillaries in patients with idiopathic dilated cardiomyopathy (DCM) or the syndrome of angina and small vessel disease (SVD), we performed electron microscopic morphometry of capillaries in right ventricular biopsy samples taken from 32 patients. Ten had angina, normal epicardial coronary arteries, and evidence for SVD; 12 had DCM; and 10 had normal hearts. In patients with DCM, the ratio of microvessels to myocytes was not different than that of controls (0.49 +/- 0.06 versus 0.51 +/- 0.05). Mean cross-sectional areas of the capillaries (lumen plus wall) and lumen were significantly greater than those of controls (45.3 +/- 15.1 versus 22.7 +/- 8.3 micron 2, p less than 0.001; 17.6 +/- 6.9 versus 11.6 +/- 6.2 micron 2, p less than 0.05, respectively). Fibrous content of the myocardium, as assessed by quantitative light microscopy, was significantly increased (16.3 +/- 3.3% versus 5.0 +/- 2.4%, p less than 0.001). In contrast, in patients with SVD, the capillary-to-myocyte ratio was reduced (0.33 +/- 0.08, p less than 0.001). Although mean cross-sectional areas of the entire capillary (32.4 +/- 19.7 micron 2) and the lumen (8.9 +/- 7.8 micron 2) were not statistically different than those of controls, there was an absence of capillaries less than 15 micron 2 in cross-sectional area, and the frequency distribution of the lumen area was skewed to the left. Swollen endothelial cells frequently encroached upon the lumen. There was a mild increase in fibrous content (9.5 +/- 3.7%, p less than 0.05).

CONCLUSIONS

Enlarged capillaries and a normal ratio of capillaries to myocytes appear to be features of DCM. Of the patients with SVD, there was both a relative lack of capillaries and capillary lumen narrowing from swollen endothelium. These changes may induce ischemia and angina and may result in mild fibrosis.
Vital organ perfusion during assisted circulation by manipulation of intrathoracic pressure.
Authors: Chandra N C , Beyar R , Halperin H R , Tsitlik J E , Wurmb E , Rayburn B , Guerci A D , Weisfeldt M L
Published: June 2012

BACKGROUND

We have previously shown, in dogs with severe cardiac depression, that modest cyclic increases in intrathoracic pressure, starting synchronously with left ventricular isovolumic contraction, significantly increase aortic flow and pressure. However, little is known of changes in vital organ perfusion during this technique of assisted circulation.

METHODS AND RESULTS

We studied regional organ flow using radioactive labeled microspheres in 13 20-25-kg mongrel dogs. In the control group, after chemical induction of cardiac depression with verapamil and propranolol, coronary flow fell from 129.1 +/- 14.4 to 51.6 +/- 11.3 ml/100 g/min (p less than 0.005) and continued to decline over a 14-minute time period (flow was 32.2 +/- 11.5 ml/100 g/min at 7 minutes and 20.7 +/- 9.5 ml/100 g/min at 14 minutes [n = 6]; all p less than 0.05). In the intervention group, regional blood flow was evaluated before and after the induction of cardiac depression and also during assisted circulation using 400-msec, 20-25-mm Hg intrathoracic pressure increases delivered by a circumthoracic pneumatic vest, starting synchronously with left ventricular isovolumic contraction. In the intervention group, coronary flow fell from 119 +/- 26.7 to 47.9 +/- 13.1 ml/100 g/min 1 minute after the induction of cardiac depression (p less than 0.005). With the initiation of assisted circulation, coronary flow increased to 55.8 +/- 19.2 ml/100 g/min at 7 minutes and fell to 23.1 +/- 15.9 ml/100 g/min on termination of assisted circulation at 14 minutes (p less than 0.05 and p = NS versus control group flows at 1 and 14 minutes, respectively). During assisted circulation, cerebral, renal, and small intestinal flows also increased (all p less than 0.05 versus flows during myocardial depression). No significant increase in hepatic flow was observed.

CONCLUSIONS

In the canine model, manipulation of intrathoracic pressure appears to be an effective, short-term, noninvasive means of not only increasing aortic pressure but also increasing vital organ perfusion during cardiogenic shock. Further studies are needed to assess the usefulness of this technique of assisted circulation in humans.
Left cardiac sympathetic denervation in the therapy of congenital long QT syndrome. A worldwide report.
Authors: Schwartz P J , Locati E H , Moss A J , Crampton R S , Trazzi R , Ruberti U
Published: June 2012

BACKGROUND

Long QT syndrome (LQTS) is a congenital disorder accompanied by a high incidence of sudden cardiac death. beta-Adrenergic blockade is the therapy of choice, and it is successful in 75-80% of patients. For those in whom cardiac events (syncope or cardiac arrest) are not prevented by beta-blockade, experimental studies suggest that left cardiac sympathetic denervation (LCSD) may be useful.

METHODS AND RESULTS

We identified 85 LQTS patients worldwide who underwent LCSD, and we provide here the first large-scale evaluation of its efficacy. The time interval between the first cardiac event and LCSD and the follow-up period after LCSD were similar (5.6 +/- 6.1 versus 5.9 +/- 5.7 years). The mean age of the patients at surgery was 20 +/- 13 years. LCSD was followed by highly significant (p less than 0.0001) decreases in the number of patients with cardiac events (from 99% to 45%), in the number of cardiac events per patient (from 22 +/- 32 to 1 +/- 3), and in the number of patients with five or more cardiac events (from 71% to 10%). There were seven sudden deaths (8%), and the 5-year survival rate was 94%. The marked reduction in the incidence of tachyarrhythmic syncope suggests that LCSD has also reduced the risk for sudden death in this high-risk population.

CONCLUSIONS

The present findings demonstrate that for LQTS patients who continue with syncope or cardiac arrest despite the use of beta-blockers, LCSD is a very effective therapy.
A prospective, randomized trial comparing combination half-dose tissue-type plasminogen activator and streptokinase with full-dose tissue-type plasminogen activator. Kentucky Acute Myocardial Infarction Trial (KAMIT) Group.
Authors: Grines C L , Nissen S E , Booth D C , Gurley J C , Chelliah N , Wolf R , Blankenship J , Branco M C , Bennett K , DeMaria A N
Published: June 2012

BACKGROUND

The potential benefits of combination thrombolytic agents in the treatment of myocardial infarction remain uncertain. In a small pilot study, we demonstrated that combining half-dose tissue-type plasminogen activator (t-PA) with streptokinase (SK) achieved a high rate of infarct vessel patency and a low rate of reocclusion at half the cost of full-dose t-PA.

METHODS AND RESULTS

We designed a prospective trial in which 216 patients were randomized within 6 hours of myocardial infarction to receive either the combination of half-dose (50 mg) t-PA with streptokinase (1.5 MU) during 1 hour or to the conventional dose of t-PA (100 mg) during 3 hours. Acute patency was determined by angiography at 90 minutes, and angioplasty was reserved for failed thrombolysis. Heparin and aspirin regimens were maintained until follow-up catheterization at day 7. Acute patency was significantly greater after t-PA/SK (79%) than with t-PA alone (64%, p less than 0.05). After angioplasty for failed thrombolysis, acute patency increased to 96% in both groups. Marked depletion of serum fibrinogen levels occurred after t-PA/SK compared with t-PA alone at 4 hours (37 +/- 36 versus 199 +/- 66 mg/dl, p less than 0.0001) and persisted 24 hours after therapy (153 +/- 66 versus 252 +/- 75 mg/dl, p less than 0.0001). Reocclusion (3% versus 10%, p = 0.06), reinfarction (0% versus 4%, p less than 0.05), and need for emergency bypass surgery (1% versus 6%, p = 0.05) tended to be less in the t-PA/SK group. Greater myocardial salvage was apparent in the t-PA/SK group as assessed by infarct zone function at day 7 (-1.9 SD/chord versus -2.3 SD/chord after t-PA alone, p less than 0.05). In-hospital mortality (6% versus 4%) and serious bleeding (12% versus 11%) were similar between the two groups.

CONCLUSIONS

These results suggest that a less expensive regimen of half-dose t-PA with SK yields superior 90-minute patency and left ventricular function and a trend toward reduced reocclusion compared with the conventional dose of t-PA.
Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation.
Authors: Sheikh K H , Bengtson J R , Rankin J S , de Bruijn N P , Kisslo J
Published: June 2012

BACKGROUND

Intraoperative transesophageal Doppler color flow imaging (TDCF) affords the opportunity to assess mitral valve competency immediately before and after cardiopulmonary bypass (CPB). The purpose of this study was to assess the utility of TDCF to assist in the selection and operative treatment of ischemic mitral regurgitation (MR).

METHODS AND RESULTS

Two hundred forty-six patients undergoing surgery for ischemic heart disease were prospectively studied. All had preoperative cardiac catheterization. Catheterization and pre-CPB TDCF were discordant in their estimation of MR in 112 patients (46%). Compared with patients in whom both techniques agreed in estimation of MR, patients with discordance in MR were more likely to have had unstable clinical syndromes at the time of catheterization (79% versus 40%, p less than 0.05) or to have received thrombolytics (16% versus 8%, p less than 0.05). Pre-CPB TDCF resulted in a change in the operative plan with respect to the mitral valve in 27 patients (11%). Because less MR was found by TDCF than catheterization, 22 patients had only coronary bypass grafting when combined coronary bypass and mitral valve surgery had been planned. Because more MR was found by TDCF than catheterization, five patients had combined coronary bypass and mitral valve surgery when coronary bypass alone had been planned. Unsatisfactory results noted by TDCF following mitral valve surgery in five patients resulted in immediate corrective surgery. Cox regression analysis identified residual MR at the completion of surgery to be an important predictor of survival (chi 2 = 21.4) after surgery--more important than patient age (chi 2 = 8.3) or left ventricular ejection fraction (chi 2 = 5.3).

CONCLUSIONS

These results indicate that TDCF is useful in guiding patient selection and operative treatment of ischemic MR and that in such patients, intraoperative TDCF should be performed routinely.
Respiratory and circulatory analysis of CO2 output during exercise in chronic heart failure.
Authors: Hachamovitch R , Brown H V , Rubin S A
Published: June 2012

BACKGROUND

The output of carbon dioxide (VCO2) is controlled by both hemodynamics and ventilation. To understand VCO2 in patients who have chronic heart failure (CHF), we studied 14 patients who had New York Heart Association functional class III failure by measurements of hemodynamics, ventilation, and arterial and venous blood gases at rest and at 50 W of cycle ergometry exercise.

METHODS AND RESULTS

Fick principle analysis of VCO2 showed that because of a limited increase in cardiac output, CHF patients widened their venoarterial CO2 content difference from 4.9 +/- 3.5 ml/dl at rest to 11.1 +/- 4.0 ml/dl with exercise (p less than 0.05). This increase in CO2 content difference was achieved with no change in venous CO2 content (from 54.3 +/- 3.3 ml/dl at rest to 54.5 +/- 4.8 ml/dl at exercise, p = NS); however, there was a decrease of arterial CO2 content (from 49.4 +/- 3.7 ml/dl at rest to 43.4 +/- 2.3 ml/dl with exercise, p less than 0.05). Modeling of the CO2 tension-content relation showed that there would have been a small, nonproportional increase of venous CO2 content as venous CO2 tension increased from 43.2 +/- 1.8 mm Hg at rest to 55.3 +/- 4.2 mm Hg during exercise (p less than 0.05); however, the development of metabolic acidosis during exercise entirely blunted the increase of CO2 content. In contrast, both the shape of the tension-content relation and the acidosis of exercise further influenced the decrease of arterial CO2 content as arterial CO2 tension decreased from 37.0 +/- 2.9 mm Hg at rest to 32.0 +/- 3.4 mm Hg during exercise (p less than 0.05) as a result of excess ventilation.

CONCLUSIONS

In CHF patients during exercise, the circulatory limitations imposed by a low cardiac output on VCO2 are compensated by a widened venoarterial CO2 content difference. The content difference is not widened through an increase of venous CO2 content but rather by a decrease of arterial CO2 content caused by arterial hypocapnia and metabolic acidosis.
Differences in electrophysiological substrate in patients with coronary artery disease and cardiac arrest or ventricular tachycardia. Insights from endocardial mapping and signal-averaged electrocardiography.
Authors: Vaitkus P T , Kindwall K E , Marchlinski F E , Miller J M , Buxton A E , Josephson M E
Published: June 2012

BACKGROUND

Many studies have combined patients with hemodynamically well-tolerated ventricular tachycardia (VT) and those with cardiac arrest (CA) as a single, homogenous group. Recent studies suggest that these two groups have different electrophysiological substrates and responses to therapy. Most of these studies, however, enrolled patients with a variety of cardiac diagnoses.

METHODS AND RESULTS

We used signal-averaged electrocardiography (SAECG) and endocardial catheter mapping to define the electrophysiological substrate in patients with coronary artery disease and VT or CA and correlate the results of the two methods. We also examined the usefulness of SAECG in CA patients to differentiate those with inducible arrhythmias from those who are noninducible. VT patients were more likely to have had a prior myocardial infarction (p = 0.0005) and to have inducible arrhythmias (p = 0.0001) than were CA patients. The induced arrhythmias in patients who presented with VT was VT in more than 90% of cases, whereas in CA patients, polymorphic ventricular tachycardia (PMVT) accounted for one third of induced arrhythmias. Mean filtered QRS duration was longer (135 versus 120 msec) and the terminal QRS voltage was smaller (20 versus 34 microV) in VT than in CA patients (p less than 0.01). Sixty-three percent of CA patients and 87% of VT patients had abnormal SAECG (p = 0.001). VT patients had more extensive endocardial abnormalities and more abnormal (53% versus 40%, p = 0.002), fractionated (8% versus 3%, p = 0.02), late (17% versus 8%, p = 0.0003), and late abnormal or fractionated (14% versus 4%, p = 0.0001) sites than CA patients. VT patients had a greater duration of the longest electrogram (129 versus 109 msec, p = 0.0006) and total endocardial activation time (68 versus 54 msec, p = 0.009). Among CA patients, those with induced VT had more extensive substrate than did those with induced PMVT and were similar to VT patients with induced VT. Among CA patients, the trend for more patients with inducible VT (77%) or PMVT (55%) than noninducible patients (47%) to have an abnormal SAECG did not reach statistical significance (p = 0.14). The positive and negative predictive values of an abnormal SAECG were 77% and 44%, respectively.

CONCLUSIONS

VT patients have more extensive endocardial substrate than CA patients, which translates into greater and more frequent SAECG abnormalities. Among CA patients, there are significant differences in substrate between patients with induced VT and those with induced PMVT. SAECG is not useful in differentiating CA patients who have inducible VT or PMVT from those who do not.
Trends in use of coronary angiography in subacute phase of myocardial infarction.
Authors: Nicod P , Gilpin E A , Dittrich H , Henning H , Maisel A , Blacky A R , Smith S C , Ricou F , Ross J
Published: June 2012

BACKGROUND

Most patients do not undergo acute reperfusion after myocardial infarction, and which of these patients should undergo coronary angiography is still debated.

METHODS AND RESULTS

We analyzed the 1-year clinical outcomes and rates of coronary angiography performed as late as 60 days after myocardial infarction in 3,804 patients admitted between 1979 and 1988 and followed in six different centers. Patients less than 75 years old were classified into low-, medium-, and high-risk groups using a multivariate analysis of historical and clinical variables gathered during the first 8 hospital days. Patients who underwent early reperfusion (17%, all after 1984) were analyzed separately. To analyze time trends, patients were compared before and after mid-1984. Mortalities from day 9 through 1 year were similar for the two time periods in the low- (3.3% versus 2.5%) and medium-risk (7.4% versus 5.6%) groups, but mortality was lower for the high-risk group after 1984 (31.6% versus 20.0%). The proportion of patients undergoing coronary angiography increased dramatically in each group after 1984 (low risk, 18% versus 48%; medium risk, 23% versus 49%; high risk, 10% versus 32%, before and after 1984, respectively). Furthermore, a large percentage of patients (more than 40%) in the low-risk group did not have at least one of the indications for coronary angiography recently recommended by a joint task force. Among patients undergoing coronary angiography, the proportion of patients with three-vessel coronary artery disease decreased after 1984, whereas the proportion undergoing mechanical revascularization in the year after infarction increased in all risk groups.

CONCLUSIONS

Despite the recent development of noninvasive techniques with high sensitivity for detecting high-risk patients after myocardial infarction, coronary angiography is being performed increasingly in all patients, including those determined to be at low risk for complications based on clinical data. The economic consequences of such a trend could be considerable, and its impact requires careful analysis.
Intravascular ultrasound assessment of lumen size and wall morphology in normal subjects and patients with coronary artery disease.
Authors: Nissen S E , Gurley J C , Grines C L , Booth D C , McClure R , Berk M , Fischer C , DeMaria A N
Published: June 2012

BACKGROUND

Necropsy studies demonstrate that coronary artery disease (CAD) is frequently complex and eccentric. However, angiography provides only a silhouette of the vessel lumen. Intravascular ultrasound is a new tomographic imaging method for evaluation of coronary dimensions and wall morphology. Few data exist regarding intravascular ultrasound in patients with CAD, and no data exist for subjects with normal coronaries.

METHODS AND RESULTS

We used a multielement 5.5F, 20-MHz ultrasound catheter to examine eight normal subjects and 43 patients with CAD. We assessed the safety of coronary ultrasound and the effect of vessel eccentricity on comparison of minimum luminal diameter by angiography and ultrasound. Normal and atherosclerotic wall morphology and stenosis severity were also evaluated by intravascular ultrasound. The only untoward effect was transient coronary spasm in five patients. At 33 sites in normal subjects, the lumen was nearly circular, yielding a close correlation between angiographic and ultrasonic minimum diameter (r = 0.92). At 90 sites in patients with CAD, ultrasound demonstrated a concentric cross section; correlation was also close (r = 0.93). However, at 72 eccentric sites, correlation was not as close (r = 0.77). For 41 stenoses, correlation between angiography and ultrasound for area reduction was moderate (r = 0.63). In normal subjects, wall morphology revealed a thin (0.30 mm or less) intimal leading edge and subadjacent sonolucent zone (0.20 mm or less). Patients with CAD exhibited increased thickness and echogenicity of the leading edge, thickened sonolucent zones, and/or attenuation of ultrasound transmission.

CONCLUSIONS

These data establish that intravascular ultrasound is feasible and safe and yields luminal measurements that correlate generally with angiography. Differences between angiographic and ultrasound measures of lumen size in eccentric vessels probably reflect the dissimilar perspectives of tomographic and silhouette imaging techniques. Intravascular ultrasound provides detailed images of normal and abnormal wall morphology not previously possible in vivo.
Randomized 4-week exercise program in patients with impaired left ventricular function.
Authors: Jetté M , Heller R , Landry F , Blümchen G
Published: June 2012

BACKGROUND

This study was designed to determine the controlled effects of a short-term exercise rehabilitation program on patients with moderate-to-severe left ventricular dysfunction after a recent myocardial infarction.

METHODS AND RESULTS

Thirty-nine male patients 51 +/- 8 years old with a large anterior myocardial infarction less than 10 weeks old were recruited for the study. The patients were randomly assigned to either one of two training or control groups on the basis of their resting ejection fraction: training, less than 30%; control, less than 30%; training, 31-50%; or control, 31-50%. Patients were evaluated for filling pressures, radionuclide ventriculography, heart volume, echocardiography, and work capacity. Patients who underwent training participated in an intensive 4-week in-hospital exercise program, whereas the control patients were restricted to a minimal activity program. Results indicated that there were no significant improvements in resting, submaximal, and maximal hemodynamic measurements as a result of the program. Mean work capacity and peak oxygen consumption improved significantly in the less-than-30% training group but was accompanied by a significant increase in mean pulmonary wedge pressure. Resting ejection fraction improved markedly in both less-than-30% training and control patients, but ejection fraction measures were not associated with work capacity. Training did not cause further deterioration in ventricular function.

CONCLUSIONS

It was concluded that in the present study, exercise training had little or no effect on hemodynamic measurements and that the training effects achieved in patients with left ventricular dysfunction are most likely due to corrected impaired vasodilation, not necessarily to cardiac function. The importance of using a control group in this type of study and the wide interindividual variations in training responses are emphasized.
Hemodynamic, renal, and hormonal responses to brain natriuretic peptide infusion in patients with congestive heart failure.
Authors: Yoshimura M , Yasue H , Morita E , Sakaino N , Jougasaki M , Kurose M , Mukoyama M , Saito Y , Nakao K , Imura H
Published: June 2012

BACKGROUND

This study was designed to examine the hemodynamic, renal, and hormonal effects of brain natriuretic peptide (BNP) infusion in patients with congestive heart failure (CHF) and in control subjects.

METHODS AND RESULTS

We infused synthetic human BNP at a rate of 0.1 micrograms/kg/min. BNP infusion decreased pulmonary capillary wedge pressure (control, from 5 +/- 1 to 2 +/- 1 mm Hg, p less than 0.01; CHF, from 21 +/- 3 to 14 +/- 4 mm Hg, p less than 0.05) and systemic vascular resistance (control, from 1,264 +/- 75 to 934 +/- 52 dyne.sec.cm-5; CHF, from 2,485 +/- 379 to 1,771 +/- 195 dyne.sec.cm-5; p less than 0.01, respectively) and increased stroke volume index (control, from 49.9 +/- 2.7 to 51.5 +/- 2.3 ml/m2, p = NS; CHF, from 25.6 +/- 3.8 to 32.0 +/- 3.9 ml/m2, p less than 0.01). BNP infusion significantly increased urine volume (control, from 2.3 +/- 0.7 to 7.5 +/- 1.9 ml/min; CHF, from 0.8 +/- 0.2 to 5.3 +/- 1.0 ml/min; p less than 0.01, respectively), excretion of sodium (control, from 79.2 +/- 21.6 to 332.8 +/- 70.9 microEq/min; CHF, from 77.4 +/- 20.8 to 753.5 +/- 108.0 microEq/min; p less than 0.01, respectively), and excretion of chloride (control, from 72.5 +/- 18.4 to 256.0 +/- 43.3 microEq/min; CHF, from 74.0 +/- 19.6 to 708.8 +/- 103.3 microEq/min; p less than 0.01, respectively). Urinary excretion of sodium and of chloride in response to BNP infusion was higher in patients with CHF than in control subjects (p less than 0.01, respectively). BNP infusion increased the levels of plasma atrial natriuretic peptide (control, from 65 +/- 11 to 84 +/- 14 pg/ml; CHF, from 262 +/- 65 to 301 +/- 62 pg/ml; p less than 0.05, respectively) and decreased plasma aldosterone concentrations in both groups (control, from 43.3 +/- 12.1 to 27.3 +/- 7.1 pg/ml; CHF, from 91.1 +/- 34.3 to 66.3 +/- 27.2 pg/ml; p less than 0.05, respectively).

CONCLUSIONS

We conclude that BNP infusion improves left ventricular function in patients with CHF by vasodilation and prominent natriuretic action.
Catheter ablation using radiofrequency current to cure symptomatic patients with tachyarrhythmias related to an accessory atrioventricular pathway.
Authors: Schlüter M , Geiger M , Siebels J , Duckeck W , Kuck K H
Published: June 2012

BACKGROUND

Recent investigations have shown that cure of patients with symptomatic tachyarrhythmias related to an accessory atrioventricular pathway may be achieved by closed-chest electrode catheter ablation of the accessory connection. Direct current shocks have primarily been used for this purpose, but its applicability is limited because of the lack of controlled titration of electrical energy, the infliction of barotrauma, and the need for general anesthesia. Radiofrequency current has been proposed as an alternate energy source.

METHODS AND RESULTS

Seventy-three symptomatic patients with Wolff-Parkinson-White syndrome and 19 patients with only retrogradely conducting (concealed) pathways underwent ablative therapy with radiofrequency current. There were 71 accessory pathways located on the left side of the heart (57 free-wall and 14 posteroseptal pathways) and 25 on the right side (11 free-wall, seven posteroseptal, and seven midseptal or anteroseptal pathways). In patients with right-sided pathways, ablation was attempted via a catheter positioned at the atrial aspect of the tricuspid annulus. In patients with a left-sided free-wall accessory pathway, a novel approach was used in which the ablation catheter was positioned in the left ventricle directly below the mitral annulus. Accessory pathway conduction was permanently abolished in 79 patients (86%). Growing experience and improved catheter technology resulted in a 100% success rate after the 52nd consecutive patient. Failures were mainly the result of inadequate catheters used initially or an unfavorable approach to left posteroseptal pathways.

CONCLUSIONS

Catheter ablation of accessory atrioventricular pathways by the use of radiofrequency current is an effective and safe therapeutic modality for patients with symptomatic tachyarrhythmias mediated by these pathways.