Citations

BACKGROUND In acute myocardial infarction, residual flow to the infarct zone either through antegrade flow in the infarct-related coronary artery or collateral flow from the non-infarct-related arteries is often present before reperfusion therapy. The purpose of this study was to assess the influence of antegrade flow in the infarct-related artery and/or collateral flow to the infarct zone before successful direct angioplasty on infarct size and myocardial salvage in patients with acute evolving myocardial infarction. METHODS AND RESULTS Sixty patients with acute evolving myocardial infarction underwent direct successful angioplasty without prior thrombolytic therapy. The myocardium at risk of infarction, the final infarct size, and myocardial salvage were measured by tomographic perfusion imaging with 99mTc sestamibi. Antegrade flow in the infarct-related artery before intervention was graded according to the Thrombolysis in Myocardial Infarction (TIMI) study group classification. Collateral flow to the infarct zone before angioplasty was also graded (0 through 3, 0 being no collateral flow). The presence of even minimal antegrade flow before angioplasty (TIMI grade 1) in the infarct-related artery compared with absent flow was associated with a significant reduction in final infarct size (9 +/- 17% versus 23 +/- 19% of left ventricle, P = .02) and a significant increase in myocardial salvage (23 +/- 16% versus 14 +/- 13% of left ventricle, P = .05) after angioplasty. When antegrade flow in the infarct-related artery was absent before angioplasty, the presence of collateral flow before angioplasty resulted in a significantly smaller final infarct size (P = .01) and more myocardial salvage (P = .05) after angioplasty. Both antegrade infarct-related artery flow and collateral flow to the infarct zone had significant independent ability to predict infarct size after angioplasty. When collateral grade and TIMI grade were added to provide an estimate of residual flow, a model including residual flow, myocardium at risk, and the interaction of residual flow and infarct site explained 83% of the variability in infarct size after angioplasty. CONCLUSIONS The presence of antegrade flow in the infarct-related artery and/or collateral flow to the infarct zone before direct angioplasty in acute evolving infarction results in a smaller infarct size after direct successful angioplasty.

BACKGROUND beta-Atrial natriuretic factor (beta-ANF) is an antiparallel dimer of alpha-ANF (alpha-ANF) with diminished cyclic GMP generation in vitro. To date, the presence of beta-ANF in the circulation of humans with severe congestive heart failure (CHF) remains controversial. The current study was designed to determine the presence and magnitude of circulating beta-ANF in severe CHF, to correlate plasma beta-ANF with the degree of ventricular dysfunction, and to investigate the role of human plasma and atrial tissue in the degradation of beta-ANF. METHODS AND RESULTS Venous plasma samples were obtained from patients (n = 12) with severe CHF and normal volunteers (n = 8). Total plasma ANF was measured by radioimmunoassay. alpha-ANF and beta-ANF in nonextracted plasma were separated by gel filtration chromatography using a P-6 column. Right atrial tissue samples (n = 5) were collected from a different group of patients at the time of open-heart surgery. 125I beta-ANF and I125 ANF were incubated with atrial tissue or plasma. The corresponding peak areas of beta-ANF were determined by Tamaya Digital Planimeter. beta-ANF represented 61% of total plasma ANF in CHF patients and was not detected in normal human plasma. The elevation of beta-ANF correlated with the severity of ventricular dysfunction. Thirty percent of beta-ANF and 100% alpha-ANF were converted to smaller peptide fragments in atrial tissue no conversion in plasma. CONCLUSIONS beta-ANF is the principal form of circulating ANF in patients with severe CHF and correlates with the degree of left ventricular dysfunction. beta-ANF is not generated from alpha-ANF and may be degraded rapidly in atrial tissue to smaller peptide fragments that do not occur in plasma. As beta-ANF is reported to have reduced biological action, the current studies may support the conclusion that the ANF system in CHF has reduced functional activity despite increases in circulation concentrations.

BACKGROUND Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) are a family of structurally related peptides that participate in the integrated control of renal and cardiovascular function. Previous studies suggest a functional role for these hormonal peptides in cardiorenal regulation in congestive heart failure (CHF). METHODS AND RESULTS The present studies were performed in normal subjects (n = 6) and in patients with mild (New York Heart Association [NYHA] class I to II, n = 20) and severe (NYHA class III to IV, n = 20) CHF by use of radioimmunoassay and immunohistochemical staining (IHCS). Plasma ANP was significantly increased in both mild and severe CHF compared with normal subjects. In contrast, plasma BNP was only moderately increased in the severe CHF group, and plasma CNP concentration was unchanged in CHF compared with normal subjects. Atrial tissue concentrations of the natriuretic peptides did not parallel circulating concentrations. ANP predominated in normal atrial tissue, but BNP predominated in CHF. In ventricular tissue, IHCS staining was present for all three peptides in normal ventricular myocardium and was markedly enhanced in CHF. CONCLUSIONS These studies support a differential regulation of ANP, BNP, and CNP circulating concentrations and tissue activity in human CHF.

BACKGROUND Atrial natriuretic factor (ANF) is produced by myocardial tissue, and the plasma ANF concentration is known to be elevated in congestive heart failure (CHF). Data from animal models indicate that myocardial concentrations of ANF are depleted in CHF, and this has given rise to the hypothesis that CHF is characterized by depletion of stored ANF. To date, the molecular forms of ANF and their concentrations in atrial and ventricular myocardium remain poorly characterized in the normal and the failing human heart. METHODS AND RESULTS We measured ANF concentrations in fresh tissue from failing human hearts explanted at the time of cardiac transplantation and from organ donors whose normal hearts could not be used for transplantation. We determined total ANF and alpha, beta, and gamma ANF concentrations in the right and left atrial appendages, atrial free walls, and ventricles. In normal hearts, ANF concentration in the atrial appendages was 40-fold higher than ANF in the rest of the atrial free wall and in the ventricles. In the failing hearts, atrial appendage ANF concentrations increased 5- to 10-fold, and atrial free wall ANF concentrations increased 200-fold. Analysis of molecular forms of ANF demonstrated significant increases in the gamma and beta forms in the left atrial appendage of failing hearts. alpha, beta, and gamma ANF forms were also significantly increased in right and left atrial free wall tissue from failing hearts. In addition, failing hearts were characterized by absolute and relative increases in the precursor form gamma ANF. CONCLUSIONS These data from fresh tissues suggest that cardiac ANF stores are not decreased in severe CHF in humans; rather, chronic CHF is characterized by marked increases in atrial ANF tissue concentrations, particularly the beta and gamma ANF forms. These findings are consistent with intracellular accumulation of precursor ANF forms in severe chronic human CHF.

BACKGROUND The instantaneous pressure gradient between the left ventricle and left atrium during systole can be calculated from the mitral regurgitation Doppler velocity curve. The purpose of our study was to determine the accuracy of measuring the time constant of relaxation (TAU) derived from the Doppler mitral regurgitation signal by comparing it with simultaneous high-fidelity left ventricular pressure measurements in humans. METHODS AND RESULTS Twenty-five patients had continuous-wave Doppler mitral regurgitation recordings performed with simultaneous high-fidelity left ventricular pressure measurements. Fifteen of these patients had measurements of six to eight beats at various RR intervals. Doppler velocity curves were converted to left ventricular pressure curves by different methods through application of the modified Bernoulli equation at 3-msec intervals. The correlation between catheter-derived and Doppler-derived TAU was best when a zero asymptote and knowledge of the left ventricular end-diastolic pressure were used. A less optimal but acceptable method used the addition of 20 mm Hg to the Doppler-derived ventriculoatrial gradient. Use of a nonzero asymptote for calculation of TAU yielded poor correlation between catheter and Doppler measurements. The correlation of percentage change in Doppler-derived TAU plotted against percentage change in catheter-derived TAU was poor. CONCLUSIONS The descending limb of the Doppler-derived mitral regurgitation velocity signal can be used as a semiquantitative estimate of the rate of ventricular relaxation. This method requires knowledge of left atrial pressure and may not be sufficiently accurate for detecting small changes in the rate of relaxation on a beat-to-beat basis.

BACKGROUND Recent studies have reported that asymptomatic left ventricular dysfunction (ALVD) in humans is characterized by early neurohumoral activation. Specifically, atrial natriuretic factor (ANF) and norepinephrine are activated without activation of the renin-angiotensin-aldosterone system (RAAS). The current study describes hemodynamic and renal function associated with this neurohumoral profile in a canine model of early and presumably "asymptomatic" ventricular dysfunction. We hypothesized that the neurohumoral profile observed in ALVD is associated with preservation of renal function despite significant hemodynamic compromise. METHODS AND RESULTS ALVD was produced by ventricular pacing at 180 beats per minute for 10 days. Intravascular volume expansion was performed before and after producing ALVD in eight conscious dogs. The model of ALVD was characterized by decreases in ejection fraction (48 +/- 2 to 29 +/- 4%), cardiac output (4.64 +/- 0.29 to 2.89 +/- 0.17 L/min), and mean arterial pressure (119 +/- 4 to 108 +/- 4 mm Hg). Atrial pressures and systemic vascular resistance were increased. ANF (60 +/- 19 to 165 +/- 27 pg/mL) and norepinephrine (382 +/- 127 to 690 +/- 211 pg/mL) were activated, whereas the RAAS was not. Creatinine clearance and sodium excretion (UNa V) were unchanged after producing ALVD. The natriuretic response to volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion in ALVD was completely intact, with increases in UNa V similar to that observed with volume expansion before producing ALVD. CONCLUSIONS The current study demonstrates that significant ventricular dysfunction with peripheral vasoconstriction can be associated with normal renal function and thus suggests an important functional role for the neurohumoral profile of ALVD in preserving sodium balance.

BACKGROUND The carcinoid syndrome is a rare cause of acquired valvular heart disease. Although the typical echocardiographic features of carcinoid heart disease are well recognized, this large series provides new information about unusual manifestations of the disease as well as the role of Doppler echocardiography. METHODS AND RESULTS Between 1980 and 1989, 132 patients with carcinoid syndrome underwent echocardiographic study. The echocardiographic, Doppler, and clinical features of the 74 patients (56%) with echocardiographic evidence of carcinoid heart disease are described. Among these patients, 97% had shortened, thickened tricuspid leaflets. Tricuspid regurgitation was present in all 69 patients with carcinoid heart disease who underwent Doppler examination, and it was of moderate or severe degree in 62 patients (90%). Severe tricuspid regurgitation was characterized by a dagger-shaped Doppler spectral profile with an early peak pressure and rapid decline. The pressure half-time was prolonged (mean, 116 msec), which is consistent with associated tricuspid stenosis. The pulmonary valve appeared thickened, retracted, and immobile in 36 patients (49%) and was diminutive to the extent of not being visualized in an additional 29 patients (39%). Among the 47 patients who underwent Doppler evaluation of the pulmonary valve, regurgitation was present in 81%, and stenosis was present in 53%. Left-sided valvular involvement was present in five patients (7%), four of whom had patent foramen ovale or carcinoid tumor involving the lung. Previously undescribed myocardial metastases were present in three patients (4%) and were confirmed by biopsy in each case. Small pericardial effusions were present in 10 patients (14%). Patients with and without echocardiographic evidence of carcinoid heart disease did not differ with regard to sex, age, location of the primary tumor, duration of diagnosis, or duration of symptoms of carcinoid syndrome. However, the mean pretreatment level of urinary 5-hydroxyindoleacetic acid was higher in patients with carcinoid heart disease than in patients without carcinoid heart disease (270 versus 131 mg/24 hrs, p < 0.001). The symptom of dyspnea was more prevalent among patients with carcinoid heart disease than in patients without the disease (54% versus 27%, p = 0.003); as expected, heart murmurs were also noted more frequently in patients with disease (92% versus 43%, p < 0.0001). Treatment regimens and response to therapy were similar in the two groups. Survival of patients with echocardiographic evidence of carcinoid heart disease was reduced compared with those without cardiac involvement (p = 0.0003). ECG and chest roentgenographic findings in patients with carcinoid heart disease were nonspecific. CONCLUSIONS The broad spectrum of carcinoid heart disease is detailed in this large series. This includes not only right-sided valvular lesions but also left-sided involvement, pericardial effusion, and myocardial metastases.

BACKGROUND Coronary revascularization with bypass has been shown to improve survival in patients with coronary artery disease and left ventricular dysfunction. In these patients, use of nonsurgical revascularization with percutaneous transluminal coronary angioplasty (PTCA) is increasing, although their long-term outcome has not been well delineated. The purpose of this investigation was to characterize the outcome of angioplasty in patients with decreased left ventricular function and contrast it with the results in patients with normal left ventricular function. METHODS AND RESULTS In the 1985-1986 National Heart, Lung, and Blood Institute's PTCA Registry, of 1,802 patients undergoing PTCA, 244 patients (13.5%) had an ejection fraction of < or = 45% (mean, 39.6 +/- 6.8%). These patients had a higher incidence of prior infarction, a longer and worse history of manifestations of coronary disease, and more extensive coronary artery disease than patients with well-preserved function; 88% and 91%, respectively, had successful dilation of at least one lesion (nonsignificant difference). However, patients with decreased left ventricular function had a decreased frequency of successful dilation of all lesions in which PTCA was attempted (76% versus 84%, p < 0.01). There were no statistically significant differences in in-hospital complications--death occurred in 0.8% and 0.7%, nonfatal myocardial infarction occurred in 4.9% and 4.5%, and emergency surgical revascularization was performed in 4.5% and 3.2%, respectively. Patients were followed for a mean of 4.1 years; during this time, patients with decreased left ventricular function had significantly worse survival and combined event-free survival. Despite this, at 4 years, 87% of the patients with a mean ejection fraction of 39.6% remained alive, and 77% were alive and had not experienced infarction or required bypass. CONCLUSIONS PTCA is effective in selected patients with depressed left ventricular function. Initial outcome and risk-benefit ratio are excellent. Successful dilation of at least one vessel was achieved in 88% of patients with depressed left ventricular function and in 91% of patients with more normal left ventricular function. The former group, however, had a decreased incidence of successful dilation in all lesions in which dilation was attempted (76% versus 84%, p < 0.01). There was no significant difference in in-hospital complications between the two groups. During follow-up, patients with decreased left ventricular function had worse event-free survival, although 77% were alive without infarction or bypass grafting at 4 years.

BACKGROUND To test the feasibility of percutaneous deployment of intracoronary polymeric stents, a prototype polyethylene terephthalate (PET) stent and a catheter-based delivery system were developed. METHODS AND RESULTS Polymeric stents were deployed in the coronary arteries of 11 Yucatan swine: six stents were placed in the left anterior descending coronary artery, four stents were placed in the circumflex artery, and one stent was placed in the right coronary artery. Stent deployment was achieved by withdrawal of an outer delivery sheath, thus allowing the PET stent to self-expand to a preformed configuration. Two animals died during surgery, one during stent placement and the other several hours after implantation due to intracoronary thrombus formation. Two animals were electively sacrificed within 24 hours of stent implant to examine the adequacy of stent deployment within the coronary vessel. The remaining seven animals survived until the termination of the study 4-6 weeks later. Light microscopic examination of the stented vessels showed an extensive neointimal proliferative response with vessel occlusion in all animals who survived initial stent placement. There were two distinct types of histological responses to the PET stent--a chronic foreign body inflammatory response around the stent tines and a neointimal proliferative response in the center of the occluded vessel lumen. The histological response seen in the central area of the vessel was morphologically similar to that seen in patients with restenosis after successful percutaneous transluminal coronary angioplasty, whereas the morphological response seen at the periphery of the stent tine was similar to that exhibited by a chronic foreign body reaction and was not typical of that seen in a restenosis lesion. A ventricular aneurysm also developed in the area of myocardium that was previously supplied by the occluded vessel. CONCLUSIONS This study demonstrates that percutaneous deployment of polymeric stents in the coronary arteries is technically feasible. The use of PET polymer was associated with an intense proliferative neointimal response that resulted in complete vessel occlusion. Histological examination of the stented segments of the vessel revealed no evidence that dissection of the vessel wall had occurred at the time of initial stent deployment. Although the PET polymer was of similar quality to that used in the manufacture of balloon angioplasty catheters, a toxic chemical or contaminant effect cannot be completely excluded as the stimulus to intimal proliferation. This finding may have relevance to the selection of materials for use as intravascular devices.