Long-term follow-up of patients with mild coronary artery disease and endothelial dysfunction.

BACKGROUND: Coronary endothelial dysfunction is characterized by vasoconstrictive response to the endothelium-dependent vasodilator acetylcholine. Although endothelial dysfunction is considered an early phase of coronary atherosclerosis, there is a paucity of information regarding the outcome of these patients. Thus, this study was designed to evaluate the outcome of patients with mild coronary artery disease on the basis of their endothelial function. METHODS AND RESULTS: Follow-up was obtained in 157 patients with mildly diseased coronary arteries who had undergone coronary vascular reactivity evaluation by graded administration of intracoronary acetylcholine, adenosine, and nitroglycerin and intracoronary ultrasound at the time of diagnostic study. Patients were divided on the basis of their response to acetylcholine into 3 groups: group 1 (n=83), patients with normal endothelial function; group 2 (n=32), patients with mild endothelial dysfunction; and group 3 (n=42), patients with severe endothelial dysfunction. Over an average 28-month follow-up (range, 11 to 52 months), none of the patients from group 1 or 2 had cardiac events. However, 6 (14%) with severe endothelial dysfunction had 10 cardiac events (P<0.05 versus groups 1 and 2). Cardiac events included myocardial infarction, percutaneous or surgical coronary revascularization, and/or cardiac death. CONCLUSIONS: Severe endothelial dysfunction in the absence of obstructive coronary artery disease is associated with increased cardiac events. This study supports the concept that coronary endothelial dysfunction may play a role in the progression of coronary atherosclerosis.

Assessment of permanent dual-chamber pacing as a treatment for drug-refractory symptomatic patients with obstructive hypertrophic cardiomyopathy. A randomized, double-blind, crossover study (M-PATHY).

BACKGROUND: Dual-chamber pacing (DDD) has been proposed as a treatment alternative to surgery for severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM), based largely on uncontrolled studies. METHODS AND RESULTS: This prospective, multicenter trial assessed pacing in 48 symptomatic HCM patients with >/=50 mm Hg basal gradient, refractory to drug therapy. Patients were randomized to 3 months each of DDD pacing and pacing backup (AAI-30) in a double-blind, crossover study design, followed by an uncontrolled and unblinded 6-month pacing trial. With randomization, no significant differences were evident between pacing and no pacing for subjective or objective measures of symptoms or exercise capacity, including NYHA functional class, quality of life score, treadmill exercise time or peak oxygen consumption. After 6 additional months of unblinded pacing, functional class and quality of life score were improved compared with baseline (P<0.01), but peak oxygen consumption was unchanged. Outflow gradient decreased 40%, 82+/-32 mm Hg to 48+/-32 mm Hg (P<0. 001), and was reduced in 57% of patients but showed no change or an increase in 43%. At 12 months, 6 individual patients (12%) showed improved functional capacity; each was 65 to 75 years of age. Left ventricular wall thicknesses in the overall study group showed no remodeling between baseline (22+/-5 mm) and 12 months (21+/-5 mm; P=NS). CONCLUSIONS: (1) Pacing cannot be regarded as a primary treatment for obstructive HCM; (2) with randomization, perceived symptomatic improvement was most consistent with a substantial placebo effect; (3) longer, uncontrolled pacing periods were associated with some subjective benefit but unaccompanied by objective improvement in cardiovascular performance and should be interpreted cautiously; (4) modest reduction in outflow gradient was achieved in most patients; and (5) a small subset (12%) >/= 65 years of age showed a clinical response, suggesting that DDD pacing could be a therapeutic option for some elderly patients.

Clinical utility of Doppler echocardiography and tissue Doppler imaging in the estimation of left ventricular filling pressures: A comparative simultaneous Doppler-catheterization study.

BACKGROUND: Noninvasive assessment of diastolic filling by Doppler echocardiography provides important information about left ventricular (LV) status in selected subsets of patients. This study was designed to assess whether mitral annular velocities as assessed by tissue Doppler imaging are associated with invasive measures of diastolic LV performance and whether additional information is gained over traditional Doppler variables. METHODS AND RESULTS: One hundred consecutive patients referred for cardiac catheterization underwent simultaneous Doppler interrogation. Invasive measurements of LV pressures were obtained with micromanometer-tipped catheters, and the mean LV diastolic pressure (M-LVDP) was used as a surrogate for mean left atrial pressure. Doppler signals from the mitral inflow, pulmonary venous inflow, and TDI of the mitral annulus were obtained. Isolated parameters of transmitral flow correlated with M-LVDP only when ejection fraction <50%. The ratio of mitral velocity to early diastolic velocity of the mitral annulus (E/E') showed a better correlation with M-LVDP than did other Doppler variables for all levels of systolic function. E/E' <8 accurately predicted normal M-LVDP, and E/E' >15 identified increased M-LVDP. Wide variability was present in those with E/E' of 8 to 15. A subset of those patients with E/E' 8 to 15 could be further defined by use of other Doppler data. CONCLUSIONS: The combination of tissue Doppler imaging of the mitral annulus and mitral inflow velocity curves provides better estimates of LV filling pressures than other methods (pulmonary vein, preload reduction). However, accurate prediction of filling pressures for an individual patient requires a stepwise approach incorporating all available data.

Annulus paradoxus: transmitral flow velocity to mitral annular velocity ratio is inversely proportional to pulmonary capillary wedge pressure in patients with constrictive pericarditis.

BACKGROUND: The early diastolic velocity of the mitral annulus (E') is reduced in patients with diastolic dysfunction and increased filling pressures. Because transmitral inflow early velocity (E) increases progressively with higher filling pressures, E/E' has been shown to have a strong positive relationship with pulmonary capillary wedge pressure (PCWP) and left ventricular end-diastolic pressure. However, previous studies have primarily involved patients without a pericardial abnormality. In constrictive pericarditis (CP), E' is not reduced, despite increased filling pressures. This study evaluated the relationship between E/E' and PCWP in patients with CP. METHODS AND RESULTS: We studied 10 patients (8 men; mean age, 64+/-7 years) with surgically confirmed CP. Doppler echocardiography was performed to measure early and late diastolic transmitral flow velocities. Tissue Doppler echocardiography was performed to measure E'. PCWP was measured with right heart catheterization. All patients were in sinus rhythm. Mean E and E' were 91+/-15 cm/s and 11+/-4 cm/s, respectively. Mean PCWP was 25+/-6 mm Hg. E' was positively correlated with PCWP (r=0.69, P=0.027). There was a significant inverse correlation between E/E' and PCWP (r=-0.74, P=0.014). Despite high left ventricular filling pressures, E/E' (mean, 9+/-4) was <15 in all but 1 patient. CONCLUSIONS: Paradoxical to the positive correlation between E/E' and PCWP in patients with myocardial disease, an inverse relationship was found in patients with CP.

Determination of left-sided pressure gradients by utilizing Doppler aortic and mitral regurgitant signals: validation by simultaneous dual catheter and Doppler studies.

Continuous wave Doppler echocardiography is an accurate and reproducible method for determination of intracardiac pressure gradients in stenotic valve lesions and right-sided regurgitant lesions. Twenty-three patients with either mitral or aortic regurgitation underwent simultaneous continuous wave Doppler and dual catheter pressure recordings to determine if instantaneous pressure gradients can be accurately determined by Doppler ultrasound in left-sided regurgitant valve lesions. Using the modified Bernoulli equation, the maximal and mean pressure gradients between the left ventricle and left atrium were determined by continuous wave Doppler ultrasound in patients with mitral regurgitation and compared with simultaneous catheter-derived pressures. The mean and end-diastolic pressure gradients between the aorta and left ventricle were determined by continuous wave Doppler ultrasound in patients with aortic regurgitation and compared with simultaneous catheter-derived pressures. Diastolic half-times by both continuous wave Doppler ultrasound and catheter pressures were compared in patients with aortic regurgitation. There was a linear correlation between the mean gradients in all patients (r = 0.94; SEE = 6 mm Hg) with a similar correlation between the instantaneous gradients (r = 0.98; SEE = 8 mm Hg). There was a linear correlation between diastolic half-times by catheter and Doppler ultrasound (r = 0.95; SEE = 39 ms). As with other valvular lesions, continuous wave Doppler echocardiography can be used in patients with mitral or aortic regurgitation to accurately determine intracardiac pressure gradients.

Evaluation of diastolic filling of left ventricle in health and disease: Doppler echocardiography is the clinician's Rosetta Stone.

Abnormalities of diastolic function have a major role in producing the signs and symptoms of heart failure. However, diastolic function of the heart is a complex sequence of multiple interrelated events, and it has been difficult to understand, diagnose and treat the various abnormalities of diastolic filling that occur in patients with heart disease. Recently, Doppler echocardiography has been used to examine the different diastolic filling patterns of the left ventricle in health and disease, but confusion about diagnosis and treatment options has arisen because of the misinterpretation of these flow velocity curves. This review presents a simplified approach to understanding the process of diastolic filling of the left ventricle and interpreting the Doppler flow velocity curves as they relate to this process. It has been hypothesized that transmitral flow velocity curves show a progression over time with diseases involving the myocardium. This concept can be applied clinically to estimate left ventricular filling pressures and to predict prognosis in selected groups of patients. Specific therapy for diastolic dysfunction based on Doppler flow velocity curves is discussed.

Mechanism of hemodynamic improvement by dual-chamber pacing for severe left ventricular dysfunction: an acute Doppler and catheterization hemodynamic study.

OBJECTIVES: This study was undertaken to determine the mechanism by which improvement in hemodynamic variables may occur with dual-chamber pacing in patients with severe left ventricular dysfunction. BACKGROUND: Dual-chamber pacing has recently been proposed as a therapeutic alternative for the relief of symptoms in patients with dilated cardiomyopathy. METHODS: Fifteen patients with severe left ventricular systolic dysfunction were studied acutely during atrioventricular (AV) sequential pacing at various AV intervals (60, 100, 120, 140, 180 and 240 ms) with use of combined Doppler velocity curves and pressures obtained by high fidelity manometer-tipped catheters and thermodilution cardiac output. RESULTS: Neither cardiac output nor mean left atrial pressure was significantly different when hemodynamic variables in the baseline state were compared with those during AV sequential pacing at the various AV intervals in all patients. The patients were classified into two groups. In group I (eight patients with PR intervals > 200 ms on the rest 12-lead electrocardiogram), cardiac output was significantly increased when AV sequential pacing at the optimal AV interval to output was compared with that at the baseline state (3.0 +/- 1.0 vs. 3.9 +/- 0.43 liters/min, p = 0.005) because timing of mechanical atrial and ventricular synchrony was optimized. In addition, left ventricular end-diastolic pressure and duration of diastolic filling were increased, and diastolic mitral regurgitation was abolished. In group II (seven patients who had normal AV conduction at rest), cardiac output during AV pacing decreased from the baseline value without change in the diastolic filling period. CONCLUSIONS: Dual-chamber pacing may improve acute hemodynamic variables in selected patients with dilated cardiomyopathy, mainly by optimization of the timing of mechanical atrial and ventricular synchrony. Reestablishment of the optimal diastolic filling period and abolition of diastolic mitral regurgitation may also contribute to hemodynamic improvement.

Accurate measurement of the transmitral gradient in patients with mitral stenosis: a simultaneous catheterization and Doppler echocardiographic study.

OBJECTIVES: This study compared the accuracy of Doppler echocardiography with that of conventional cardiac catheterization in the measurement of transmitral gradients in patients with mitral stenosis. BACKGROUND: Simultaneous measurement of left atrial and left ventricular pressures is the most accurate method for determination of the mean mitral valve gradient in patients with mitral stenosis. Because of the inherent risks of transseptal catheterization, pulmonary capillary wedge pressure has been used in many invasive laboratories for determination of the mean mitral valve gradient. Recent studies have observed significant errors when pulmonary capillary wedge pressure was used for these measurements. Doppler echocardiography provides a noninvasive alternative for measurement of the transmitral gradient, but its relative accuracy has remained unclear. METHODS: Seventeen patients with mitral stenosis who underwent transseptal cardiac catheterization had simultaneous measurement of 1) transmitral gradient by direct left atrial and left ventricular pressures, 2) transmitral gradient by pulmonary capillary wedge and left ventricular pressures, and 3) transmitral gradient by Doppler echocardiography. RESULTS: Transmitral gradient measured by pulmonary capillary wedge and left ventricular pressures significantly overestimated the gradient obtained by direct measurement of left atrial pressure, with a mean (+/- SD) difference of 3.3 +/- 3.5 mm Hg (or 53%). Correcting the pulmonary capillary wedge pressure for the phase shift resulted in better correlation, but a consistent overestimation still remained, with a mean difference of 2.5 +/- 2.9 mm Hg (or 43%). The best correlation with the smallest variability was comparison of the Doppler-derived mean gradient with the gradient from direct measurement of left atrial and left ventricular pressures, with a mean difference of 0.2 +/- 1.2 mm Hg. CONCLUSIONS: Compared with the transmitral gradient obtained by direct measurement of left atrial and left ventricular pressures, the Doppler-derived gradient is more accurate than that obtained by conventional cardiac catheterization and should be considered the reference standard.

Natural history of moderate aortic stenosis.

The natural history of severe, symptomatic aortic stenosis has been well documented. However, the natural history of moderate aortic stenosis remains poorly understood. Therefore, a group of 66 patients was identified who had a diagnosis of moderate aortic stenosis at the time of cardiac catheterization (aortic valve area 0.7 to 1.2 cm2) and who did not have surgical therapy during the 1st 180 days after cardiac catheterization. During a mean follow-up period of 35 months, 14 patients died of causes attributed to aortic stenosis and 21 underwent aortic valve replacement. The estimated probability for remaining free of any complication of aortic stenosis at the end of the first 4 years was 59%. Symptomatic patients with decreased ejection fraction or hemodynamic evidence of left ventricular decompensation were at greater risk for these complications. It is concluded that patients with moderate aortic stenosis are at significant risk for the development of complications.

Follow-up of patients with low output, low gradient hemodynamics after percutaneous balloon aortic valvuloplasty: the Mansfield Scientific Aortic Valvuloplasty Registry.

Symptomatic patients with a low cardiac output and low aortic valve gradient have a poor prognosis but are at high risk for aortic valve surgery. The outcome of percutaneous balloon aortic valvuloplasty in this subgroup of patients is unclear. Therefore, 67 patients (group 1) underwent percutaneous balloon aortic valvuloplasty between December 1, 1986 and November 1, 1987 who had a low cardiac index (less than 2.5 liters/min per m2) and a low aortic valve gradient (less than or equal to 40 mm Hg) before the procedure. The results were compared with 200 patients (group 2) who had a low cardiac index but not a low aortic valve gradient (greater than 40 mm Hg) before the procedure and who had similar baseline presenting symptoms. After balloon aortic valvuloplasty, there was a greater decrease in aortic valve gradient in patients in group 2 than in patients in group 1 (mean +/- SD -33.0 +/- 16.7 mm Hg and -14.6 +/- 6.9 mm Hg, respectively; p less than 0.001) although there was no significant difference in improvement in estimated aortic valve area (0.31 +/- 0.21 and 0.31 +/- 0.22 cm2, respectively; p = NS). In-hospital mortality was 11.9% for patients in group 1 which was not significantly different from the 7.5% mortality for patients in group 2. However, the actuarial probability of survival at 12 months for patients who survived the initial hospitalization was 46% in group 1 and 64% in group 2 (p less than 0.05). Moreover, at follow-up (mean 8.8 months) 64% of surviving group 1 patients displayed clinical improvement, compared with 70% of surviving group 2 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

In-hospital mortality after balloon aortic valvuloplasty: frequency and associated factors.

Percutaneous balloon aortic valvuloplasty has been accompanied by significant early periprocedural morbidity and mortality. Identification of factors associated with increased mortality might allow for improved selection of patients. The Mansfield Scientific Balloon Aortic Valvuloplasty Registry was analyzed to identify the frequency of in-hospital death and the factors associated with it. Of 492 patients undergoing the procedure, 37 (7.5%) died during the hospital stay in which valvuloplasty was performed. Twenty-four of these patients died within the first 24 h and the remainder died within 7 days after the procedure. There were significant differences in baseline clinical and hemodynamic characteristics as well as procedural and postprocedural variables between patients dying and those surviving the in-hospital period. Multivariate analysis identified four factors associated with increased mortality: 1) the occurrence of a procedure-related complication, 2) a lower initial left ventricular systolic pressure, 3) a smaller final aortic valve area, and 4) a lower baseline cardiac output. Thus, baseline hemodynamic, procedural and postprocedural variables and complications can be identified that are associated with increased mortality.

Patient age and results of balloon aortic valvuloplasty: the Mansfield Scientific Registry experience. The Mansfield Scientific Aortic Valvuloplasty Registry Investigators.

Patients enrolled in the Mansfield Scientific Aortic Valvuloplasty Registry were followed up a mean of 7 months after balloon aortic valvuloplasty. Results were compared for patients less than 70, 70 to 79 and greater than or equal to 80 years of age at time of valvuloplasty. As assessed by aortic valve area indexed to body surface area, stenosis was more severe in the older patients and the incidence of congestive heart failure was also greater in those aged greater than or equal to 80 years. The results of valvuloplasty were comparable in all three age groups, and indexed final valve area was not significantly different among the groups. In-hospital mortality ranged from 4.2% to 9.4%, but this and other complications were not significantly different among the groups. Total 7 month mortality was 23%. As performed in this registry study, balloon aortic valvuloplasty produced similar results in older and younger patients, despite initially more severe disease in the older patients.

Failure of calcium channel blockers to improve ventricular relaxation in humans.

OBJECTIVES: The objective of this study was to ascertain whether the reversal of low peak filling rates after administration of calcium channel blockers in patients with diastolic dysfunction indicates true improvement in the rate of ventricular relaxation and left ventricular end-diastolic pressure measured by invasive indexes. BACKGROUND: Depressed filling rates measured noninvasively have been associated with diastolic dysfunction, specifically abnormal relaxation of the left ventricle. There is a reversal of these low peak filling rates after administration of calcium channel blockers. METHODS: Doppler echocardiographic measurements of peak filling rates were made and invasive high fidelity manometer-tipped pressures were measured before and after administration of verapamil (0.1 mg/kg body weight) in 20 patients with coronary artery disease who had an ejection fraction > 40% and decreased peak filling rates. RESULTS: Verapamil caused significant increases in the peak filling rate, as measured by early transmitral (E) flow velocity, from 0.57 +/- 0.16 m/s to 0.77 +/- 0.15 m/s (p < 0.01), indicating reversal of decreased peak filling rates. Concomitantly, left ventricular end-diastolic pressure increased from 18.0 +/- 7.7 mm Hg to 24.1 +/- 9.0 mm Hg (p < 0.001). The time constant of relaxation was variable, with an overall significant increase from 45.8 +/- 10.4 ms to 53.2 +/- 14.6 ms (p = 0.01). CONCLUSIONS: Verapamil administered intravenously produced reversal of decreased peak filling rates in patients with coronary artery disease and normal ventricular function. However, there was an increase in left ventricular end-diastolic pressure as well as an overall prolongation of the time constant of relaxation. Therefore, changes in peak filling rates do not accurately reflect the response of ventricular relaxation to drug interactions. Thus, calcium channel blockers should be used cautiously in the empiric treatment of patients with diastolic dysfunction.

Utility of preload alteration in assessment of left ventricular filling pressure by Doppler echocardiography: a simultaneous catheterization and Doppler echocardiographic study.

OBJECTIVES: The aim of this study was to demonstrate the usefulness of preload alterations in assessing left ventricular filling pressures with transmitral Doppler velocity curves. BACKGROUND: Doppler mitral inflow velocities, used to estimate left ventricular filling pressures noninvasively, are limited in predicting left ventricular filling pressures, especially in patients with normal systolic function and a "pseudonormal" mitral filling pattern. METHODS: Forty-nine patients were studied in the cardiac catheterization laboratory with simultaneous Doppler echocardiography using high fidelity catheters to compare left ventricular diastolic filling pressures (pre-A wave left ventricular pressure) and Doppler mitral inflow at baseline and during reduction of preload during the strain phase of the Valsalva maneuver (n = 27) or sublingual nitroglycerin (n = 36), or both (n = 14). Doppler measurements consisted of E (initial peak velocity), A (velocity at atrial contraction), deceleration time (time from E velocity to deceleration of flow extrapolated to baseline) and absolute A wave velocity (A' [peak A wave velocity minus velocity at onset of atrial contraction]). RESULTS: In patients with high pre-A wave pressure (> or 15 mm Hg), there was a greater change in the E/A' ratio during the Valsalva maneuver than in patients with a normal pre-A wave pressure (-1.22 +/- 1.1 vs. -0.35 +/- 0.17; p = 0.02). A similar change was seen when comparing the change in the E/A' ratio after administration of nitroglycerin in patients with a high versus a normal pre-A wave pressure (0.81 +/- 0.49 vs. 0.18 +/- 0.17; p < 0.001). These differences were present in patients with a normal E/A ratio at baseline. CONCLUSIONS: Alterations in preload during assessment of Doppler echocardiographic indexes may be useful in noninvasively assessing left ventricular filling pressures.

The natural history of adults with asymptomatic, hemodynamically significant aortic stenosis.

The natural history of asymptomatic, hemodynamically significant, valvular aortic stenosis in adults was documented. Of 471 patients with aortic stenosis identified by Doppler echocardiography (peak systolic flow velocity greater than or equal to 4 m/s) from January 1984 through August 1987, 143 were asymptomatic and had isolated valvular aortic stenosis. Thirty patients underwent aortic valve intervention within 3 months (group 1); the remaining 113 patients did not have an intervention within 3 months (group 2). Follow-up information was available for all patients; the mean duration of follow-up study was 20 months (range 6 to 48). Three cardiac events occurred in the 30 group 1 patients after operation (two deaths, one reoperation). Among the 113 group 2 patients, three had cardiac death presumed to be a result of the aortic stenosis; all three developed symptoms at least 3 months before death. The actuarial probability of remaining free of symptoms of angina, dyspnea or syncope for group 2 was 86% at 1 year and 62% at 2 years. For this group, the 1 and 2 year probabilities of remaining free of cardiac events, including aortic valve intervention or cardiac death, were 93% and 74%, respectively. Of all clinical and echocardiographic variables (group 2), only Doppler flow velocity (p = 0.004) and ejection fraction (p = 0.01) were independent predictors of subsequent cardiac events. Among the 44 patients (groups 1 and 2) with a flow velocity greater than or equal to 4.5 m/s, the relative risk of sustaining a cardiac event (by Cox regression analysis) was 4.9 (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Diaphragmatic hernia mimicking an atrial mass: a two-dimensional echocardiographic pitfall.

Two-dimensional echocardiography has become the diagnostic method of choice for identifying intracardiac masses. However, adjacent extracardiac structures may closely mimic intracardiac masses on the two-dimensional echocardiogram. Five cases of a previously unrecognized phenomenon in which a diaphragmatic hernia mimicked an intraatrial mass are reported. Techniques to identify a diaphragmatic hernia properly on two-dimensional echocardiographic examination and distinguish it from intracardiac masses are discussed.

Effect of dual-chamber pacing on systolic and diastolic function in patients with hypertrophic cardiomyopathy. Acute Doppler echocardiographic and catheterization hemodynamic study.

OBJECTIVES: This study sought to evaluate prospectively the acute hemodynamic effect of dual-chamber pacing by using a combined hemodynamic approach of high fidelity pressure and Doppler velocity measurements. BACKGROUND: Dual-chamber pacing has been proposed recently as an alternative in the symptomatic treatment of patients with hypertrophic obstructive cardiomyopathy. Although early reports documented a decrease in left ventricular outflow tract gradient and symptomatic improvement, questions remain about the hemodynamic effects of dual-chamber pacing on systolic and diastolic function. METHODS: Twenty-nine patients with hypertrophic cardiomyopathy underwent a combined cardiac catheterization and Doppler echocardiographic study during normal sinus rhythm and P-synchronous pacing at various atrioventricular (AV) intervals. High fidelity pressure measurements of left ventricular inflow and left atrial pressures, ascending aortic pressure, thermodilution cardiac output and Doppler mitral flow velocity curves were obtained to evaluate both systolic and diastolic left ventricular function. RESULTS: During AV pacing at the shortest delay of 60 ms, there was a significant decrease in cardiac output (p < 0.05) and peak positive dP/dt (p < 0.05), an increase in mean left atrial pressure (p < 0.05) and a prolongation of tau, the time constant of relaxation (p < 0.05), compared with that during normal sinus rhythm. During pacing at the optimal AV delay (longest AV interval with pre-excitation), there was a similar trend, with deterioration in both systolic and diastolic function variables but of lesser magnitude than that during pacing at the shortest AV intervals. The deterioration in both systolic and diastolic function was present in 21 patients with and 8 without left ventricular outflow obstruction. There was a modest decrease in left ventricular outflow tract gradient from 73.3 +/- 45.0 (mean +/- SD) to 61.3 +/- 40.5 mm Hg (p = 0.03) during dual-chamber pacing at the optimal AV delay compared with that during normal sinus rhythm. CONCLUSIONS: The acute effect of pacing the right atrium and ventricle may be detrimental to both systolic and diastolic function of the left ventricle, particularly at the short AV intervals. Further studies of the long-term effects of dual-chamber pacing in carefully performed randomized studies are needed.

Assessment of myocardial perfusion by videodensitometry in the canine model.

Assessment of the functional severity of coronary stenoses has become increasingly important as the intrinsic limitations of coronary angiography have been documented. Videodensitometric coronary flow reserve has been proposed as a means to assess the physiologic significance of a coronary stenosis in humans. This study compared videodensitometric assessment of coronary flow with microsphere quantitation in the closed chest canine model. In five dogs, flow rates were assessed at baseline, after vasodilation with adenosine, after vasoconstriction with vasopressin and during rapid cardiac pacing. The videodensitometric peak density, time to one-half peak density and washout time (time from peak to one-half peak density) were compared at each flow state with flow assessed by microsphere injection. Reproducibility of videodensitometric measurements from two different coronary injections during the same flow state was best with peak density (r = 0.94). Videodensitometric flow ratios (flow state under study to flow at rest) using peak density demonstrated a fair correlation with flow ratios by microsphere (r = 0.81). There was poor correlation between flow ratios when time to one-half peak or washout time was used. Videodensitometric flow measurements used in vivo to assess a wide range of drug-induced coronary flows may not accurately reflect coronary flow measured by microsphere.

Doppler echocardiographic observations during percutaneous aortic balloon valvuloplasty.

To evaluate the hemodynamic changes occurring with percutaneous aortic balloon valvuloplasty for aortic stenosis, Doppler echocardiography was performed during the procedure in 16 patients. During balloon inflation, peak velocity and ejection time of the aortic valve systolic signals increased (26 and 30%, respectively; p less than 0.001). Aortic regurgitation deceleration time decreased from 1,337 to 625 ms (p less than 0.001). In three patients, aortic regurgitation stopped before end-diastole; in four patients, end-diastole forward flow across the aortic valve was documented. The deceleration time of the mitral valve inflow signal decreased from 303 to 194 ms (p less than 0.001) during balloon inflation, concurrently with an increase in left ventricular diastolic pressure. Mitral regurgitation signals became more prominent during inflation in 10 patients. Changes that occur during balloon inflation in the aortic valve include progressive left ventricular outflow obstruction, equalization of diastolic aortic and left ventricular pressures and changes in diastolic compliance.

Doppler evaluation of patients with constrictive pericarditis: use of tricuspid regurgitation velocity curves to determine enhanced ventricular interaction.

OBJECTIVES: This study sought to examine the value of analyzing Doppler echocardiographically derived tricuspid regurgitation signals during respiration in relation to the diagnosis of constrictive pericarditis. BACKGROUND: A physiologic hallmark of constrictive pericarditis is enhanced ventricular interdependence, which produces reciprocal changes in right and left ventricular filling and ejection dynamics during the respiratory cycle. It was hypothesized that these changes could be detected noninvasively by analyzing Doppler echocardiographically derived tricuspid regurgitation signals and that this information could assist in noninvasively diagnosing constrictive pericarditis. METHODS: Simultaneous Doppler echocardiography and catheterization studies of the right and left sides of the heart with high fidelity pressure manometers were performed in 5 patients with surgically confirmed constrictive pericarditis and 12 patients (control subjects) with heart failure due to other causes. RESULTS: Changes observed in tricuspid regurgitation Doppler echocardiographic variables from onset to peak inspiration in patients with constrictive pericarditis were significantly different from those in control subjects. Mean (+/- SD) percent change in maximal tricuspid regurgitation velocity was 13% +/- 6% and -8% +/- 7% in the constrictive pericarditis and control groups, respectively (p < 0.0001); mean percent change in tricuspid regurgitation signal duration was 18% +/- 2% and -2% +/- 7%, respectively (p < 0.0001); mean percent change in tricuspid regurgitation time velocity integral was 27% +/- 15% and -10% +/- 12%, respectively (p < 0.0001). CONCLUSIONS: Respiratory changes in Doppler echocardiographically derived tricuspid regurgitation peak velocity and velocity duration are increased in patients with constrictive pericarditis and may be helpful in diagnosing this condition noninvasively.