Relation between Doppler color flow variables and invasively determined jet variables in patients with aortic regurgitation.

OBJECTIVES: The purpose of this study was to test the hypothesis that invasively derived jet variables including regurgitant orifice area and momentum determine the characteristics of Doppler color flow jets in patients with aortic regurgitation. BACKGROUND: In vitro studies have demonstrated that the velocity distribution of a regurgitant jet is best characterized by the momentum of the jet, which incorporates orifice area and velocity of flow through the orifice. METHODS: Peak jet momentum, peak flow rate and regurgitant orifice area were determined with intraaortic Doppler catheter and cardiac catheterization techniques in 22 patients with chronic aortic regurgitation. These invasively derived variables were compared with apical and parasternal long-axis Doppler color echocardiographic variables obtained in the catheterization laboratory. RESULTS: Jet momentum increased significantly with the angiographic grade of regurgitation. The apical color jet area of aortic regurgitation increased linearly with jet momentum and regurgitant orifice area in vivo, but the correlations were only moderately good (r = 0.63 and 0.65, respectively). Color jet length also increased linearly with jet momentum and with regurgitant orifice area. There was only a trend for Doppler color jet width to increase with all invasively derived jet variables. CONCLUSIONS: Whereas jet area by Doppler color flow imaging is directly related to both orifice area and jet momentum in vivo, Doppler color variables measured in planes normal to the orifice do not correlate well enough with either jet momentum or regurgitant orifice area to predict jet flow variables in patients with aortic regurgitation. It is likely that the important influence of adjacent boundaries will limit the use of the velocity distribution of aortic regurgitant jets for determining the severity of disease.

The mechanism of decrease in dynamic mitral regurgitation during heart failure treatment: importance of reduction in the regurgitant orifice size.

OBJECTIVES: The purpose of this study was to quantify and characterize the regurgitant flow pattern and regurgitant orifice area in patients undergoing therapy for severe heart failure using contemporary echocardiographic techniques. BACKGROUND: Mitral regurgitation may be dynamic in patients with heart failure and ultimately correlate with outcome in a group of patients. METHODS: Fourteen patients with severe heart failure felt to require hemodynamic monitoring for the optimization of medical therapy were enrolled. Two-dimensional and Doppler echocardiograms were performed before and following invasively guided therapy. Hemodynamics and standard echocardiographic dimensions were determined as well as regurgitant volume and regurgitant orifice area derived from color M-mode and Doppler measurements. RESULTS: Invasively guided therapy for heart failure was associated with a reduction in weight, filling pressures of the left and right heart, systemic vascular resistance, and echocardiographic left atrial, left ventricular and mitral annular dimensions. The mitral regurgitant volume decreased from 47+/-27 ml before therapy to 14+/-14 ml after therapy; p < 0.001. While therapy for heart failure markedly attenuated the volume of regurgitation, the pattern of regurgitant flow across the mitral valve was not significantly altered. In contrast, there was no difference in the velocity time integral of the continuous-wave Doppler spectra of mitral regurgitation with therapy (128+/-23 cm to 123+/-25 cm, p = 0.23). In all patients, the regurgitant orifice area decreased with therapy from 0.55+/-0.38 cm2 to 0.21+/-0.20 cm2 (p < 0.001). CONCLUSIONS: Pharmacologic reduction in filling pressure and systemic vascular resistance leads to a reduction in the dynamic mitral regurgitation of heart failure through a reduction in the regurgitant orifice area but not through a change in the gradient across the mitral valve. Reduction of the regurgitant orifice area is likely related to decreased left ventricular volumes and decreased annular distention.

Effective aortic regurgitant orifice area: description of a method based on the conservation of mass.

The natural history of aortic regurgitation is incompletely understood in part because of the lack of a simple method to estimate the defect size. A method of determining the effective regurgitant orifice area that combines Doppler catheter and Doppler echocardiographic techniques and is based on the principle of conservation of mass (the continuity equation) is described. To validate the application of the Doppler catheter system for measuring regurgitant supravalvular diastolic flow, an in vitro model of retrograde aortic flow was used. These studies indicated that measurements of supravalvular retrograde velocity with the Doppler catheter accurately reflect retrograde diastolic velocity when the aorta is less than 4.8 cm in diameter. Twenty-three patients undergoing cardiac catheterization were studied; 20 of these patients had aortic regurgitation. Retrograde supravalvular diastolic velocity was determined from a Doppler catheter positioned above the aortic valve. The effective regurgitant orifice area was calculated with use of the Doppler catheter-derived regurgitant volume and mean transvalvular diastolic velocity as determined by either catheterization or continuous wave Doppler echocardiography. The catheterization-derived regurgitant orifice area increased with the angiographic grade of as follows: 1+ (0.04 to 0.10 cm2), 2+ (0.15 to 0.49 cm2), 3+ (0.29 to 1.11 cm2) and 4+ (1.24 to 1.33 cm2). By combining Doppler catheter, echocardiographic and cardiac catheterization techniques, the effective aortic regurgitant orifice area may be estimated; this hydrodynamic area correlates with grading by supravalvular aortography. Calculation of this area provides a quantitative alternative to aortography for estimating the severity of aortic regurgitation but should be used with caution in patients with a markedly dilated aorta.

Load dependence of the effective regurgitant orifice area in a sheep model of aortic regurgitation.

Treatment of patients with aortic regurgitation with vasodilators reduces regurgitant volume, ventricular dilation and left ventricular mass. Although these effects are presumably due to afterload reduction, it is also possible that the aortic regurgitant orifice area is not constant. To test the latter hypothesis, aortic regurgitation was created in 10 open chest sheep by partial resection of the noncoronary leaflet under direct visualization. Regurgitant flow was measured with an aortic supravalvular electromagnetic probe; aortic and left ventricular pressures were measured with catheter-tipped micromanometer pressure transducers. The effective regurgitant orifice area was calculated by a modification of the continuity equation in a manner similar to the Gorlin equation. The regurgitant orifice area was measured three times: after aortic regurgitation was created, after mean arterial pressure was increased by 15 to 25 mm Hg with intravenous dopamine and after mean arterial pressure was reduced by 15 to 25 mm Hg with intravenous sodium nitroprusside. Comparison of regurgitant volumes and areas obtained after creation of aortic regurgitation and at the conclusion of the experiment in the absence of dopamine or sodium nitroprusside demonstrated no significant change over time. Dopamine administration was associated with an 86 +/- 81% increase in regurgitant volume (p less than 0.01) and a 38 +/- 44% increase in regurgitant orifice area (p less than 0.01). Sodium nitroprusside administration resulted in a 51 +/- 14% decrease in regurgitant volume (p less than 0.001) and a 28 +/- 21% reduction in regurgitant orifice area (p = 0.007). In this model of acute aortic regurgitation, the effective regurgitant orifice area was altered by increasing or decreasing the aortic transvalvular pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Propafenone for the treatment of supraventricular tachycardia and atrial fibrillation: a meta-analysis.

The purpose of this study was to determine propafenone's effectiveness in terminating and suppressing supraventricular arrhythmias using meta-analytic techniques. Published abstracts and manuscripts with these goals were selected and data abstracted on conversion and maintenance of sinus rhythm. Data were pooled using standard meta-analytic techniques and analyzed according to observation times, trial design (randomized versus nonrandomized), and route of drug administration. Propafenone successfully terminated 83.8% (95% confidence interval 78.1-89.7%) of supraventricular tachycardias. For supraventricular tachycardias, the proportion of patients remaining in sinus rhythm without recurrent arrhythmia was 64.6% (58.1-71.1%) at 1 year. The likelihood of converting a paroxysm of atrial fibrillation (AF) increased over time, with 76.1% (72.8-79.4%) of patients in sinus rhythm 24 hours after initiation of therapy. Patients receiving intravenous therapy were more likely to convert to sinus rhythm in the first 4 hours after drug administration. The treatment benefit of propafenone versus placebo in converting sinus rhythm was greatest in the first 8 hours after treatment (treatment benefit of 31.5% [24.5-38.5%] at 4 hours and 32.9% [24.3-41.5%] at 8 hours, p <0.01). This treatment benefit decreased to 1 1.0% (-0.6-22.4%) after 24 hours. Propafenone was effective in suppressing recurrences of AF in 55.4% (51.3-59.7%) at 6 months and 56.8% (52.3-61.3%) at 12 months. Thus, propafenone is effective in terminating supraventricular tachycardias and AF in the vast majority of patients. Suppression of arrhythmia recurrences is feasible in most patients, although its effectiveness decreases over time.

Propafenone versus sotalol for suppression of recurrent symptomatic atrial fibrillation.

Because conventional antiarrhythmic therapy is often ineffective in maintaining sinus rhythm or is associated with adverse side effects in patients with atrial fibrillation (AF), there is a clinical need to test newer agents. One hundred patients with AF who had unsuccessful therapy with 1.9 +/- 1.0 type IA antiarrhythmic agents were randomized to receive either propafenone (n = 50) or sotalol (n = 50). Patients were stratified into 4 groups based on AF pattern (chronic vs paroxysmal) and left atrial size (large [> or = 4.5 cm] vs small [< 4.5]). The proportion of patients remaining in sinus rhythm on each agent was calculated for each group by the Kaplan-Meier method. For patients randomized to propafenone, 46 +/- 8%, 41 +/- 8% and 30 +/- 8% remained in sinus rhythm at 3, 6 and 12 months, respectively, after cardioversion. A similar proportion of patients treated with sotalol remained in sinus rhythm at follow-up (49 +/- 7%, 46 +/- 8% and 37 +/- 8% at 3, 6 and 12 months, respectively; p = NS). The proportion of patients remaining in sinus rhythm on propafenone and sotalol was not dependent on arrhythmia pattern or left atrial dimension. Except for constipation that occurred more frequently in patients treated with propafenone, adverse side effects were equally distributed between the 2 therapies. Two patients receiving sotalol died during follow-up. Propafenone and sotalol, 2 new antiarrhythmic agents, were found to be equally effective in maintaining sinus rhythm in 100 patients with recurrent AF. Response rates were not affected by arrhythmia pattern, left atrial size or unsuccessful prior drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic study of porcine bioprosthetic heart valves in the aortic valve position in patients without evidence of cardiac dysfunction.

To study the natural history of the hemodynamic performance of bioprosthetic heart valves, Doppler echocardiograms were recorded in a group of clinically stable patients at 2 and 5 years after replacement of native aortic valves with bioprosthetic valves. Eighteen patients completed a 2-year and 26 patients a 5-year follow-up examination. The effective orifice areas of identical models of bioprosthetic valves (Hancock II) were determined in vitro in a left-sided heart pulse duplicator system. In vivo Doppler-derived effective orifice areas were compared with the in vitro measurements for the same valve size. At both the 2- and 5-year follow-up examinations, the Doppler-derived effective orifice area was significantly less than the in vitro area (p less than 0.0001 at each interval). Ten of 16 valves evaluated serially decreased greater than 0.20 cm2 in the Doppler-derived effective orifice area between studies. The mean decrease in effective orifice area in valves evaluated serially was 0.25 +/- 0.29 cm2 (p less than 0.005). The peak transaortic gradient increased from 21 +/- 6 to 27 +/- 8 mm Hg (p less than 0.01). The mean transaortic gradient increased from 12 +/- 4 to 15 +/- 7 mm Hg (p less than 0.05). It is concluded that serial Doppler echocardiographic studies demonstrate a deterioration in the hemodynamic performance of bioprosthetic valves over time in patients with no symptoms or signs of valvular dysfunction and that Doppler echocardiography may be useful for identifying subclinical bioprosthetic valvular dysfunction.

Gender-associated differences in left ventricular geometry in patients with aortic valve disease and effect of distinct overload subsets.

Gender-associated differences may play an important role in the way the left ventricle adapts to overload. The purpose of this study is to evaluate left ventricular (LV) geometry in patients referred for aortic valve replacement with distinct overload subsets. The echocardiograms of 128 patients with isolated aortic stenosis (n = 44), mixed aortic valvular disease (n = 51), and pure aortic regurgitation (n = 33) before aortic valve replacement were evaluated. Women had better LV function as measured by ejection fraction (58% vs 52%; p = 0.01) and were slightly older (67 vs 62 years, p = 0.11). LV dimensions and volumes indexes were distinctively smaller in women irrespective of the subgroups analyzed. Men had larger LV mass and LV mass index, but women had higher LV mass/volume ratio. Gender-related differences in LV mass/volume ratio were most prominent in the aortic stenosis patients (3.1 g/ml for women vs 2.3 g/ml for men; p = 0.001), tended to decrease in mixed aortic disease (2.3 g/ml for women vs 1.8 g/ml for men; p = 0.01), and were not present in patients with pure aortic regurgitation (1.7 g/ml for women vs 1.7 g/ml for men; p = 0.83). Multivariate analysis showed that gender was independently associated with LV mass/volume ratios, after adjusting for the severity of the valvular lesion, age, LV function, and concomitant coronary bypass graft surgery. Thus, in a selected population of patients with severe aortic valvular disease, there were significant gender-related differences in LV geometry, mainly in patients exposed to chronic pressure overload.

Flow reversal in the descending aorta: a guide to intraoperative assessment of aortic regurgitation with transesophageal echocardiography.

This study assessed the value of biplane transesophageal echocardiographic assessment of diastolic flow reversal in the descending aorta as an alternative to Doppler color flow imaging in determining severity of aortic regurgitation. In 45 patients undergoing cardiac operations, the severity of aortic regurgitation was assessed by semiquantitative grading of the width of the Doppler color flow regurgitant jet relative to the left ventricular outflow tract, and the presence of diastolic flow reversal was assessed with pulsed-wave Doppler measurements at three sites in the descending aorta. In four patients, the diastolic flow reversal method was the only available form of assessment because of inadequate visualization of the left ventricular outflow tract beneath a mitral valve prosthesis. Diastolic flow reversal in the descending aorta was not observed in patients without aortic regurgitation and was always present in patients with severe aortic regurgitation. Aortic valve replacement successfully eliminated descending aortic flow reversal in all 19 patients in whom it was present before valve replacement. Identification of diastolic flow reversal at multiple sites in the descending aorta with biplane transesophageal echocardiography helps to confirm the presence of severe aortic regurgitation and can serve as an alternative method of assessment when visualization of the left ventricular outflow tract is impaired.

Left ventricular pseudoaneurysm after epicardial patch electrode placement.

There are many known complications of implantable cardioverter-defibrillator placement. We treated a patient in whom a left ventricular pseudoaneurysm developed secondary to epicardial patch electrode placement and cardioverter-defibrillator implantation. The presenting symptoms, diagnostic evaluation, and surgical repair are described.

Progressive enlargement of the regurgitant orifice in patients with chronic aortic regurgitation.

The severity of aortic regurgitation is dependent on the size of the regurgitant orifice, the left ventricular response to volume overload, and the diastolic pressure difference across the aortic valve. The purpose of this study was to test the hypothesis that the aortic regurgitant orifice increases over time in patients with audible chronic aortic regurgitation. To assess serial changes in aortic regurgitant severity by the use of two-dimensional and Doppler echocardiography, 59 patients (29 men and 30 women) with audible chronic aortic regurgitation were prospectively identified and evaluated annually with two-dimensional and Doppler echocardiograms. Patients were followed for a median of 38 months. We measured two separate indicators of the size of the regurgitant orifice: the color Doppler regurgitant jet width and the Doppler-derived regurgitant orifice area. Jet width increased with time (0.5 +/- 0.4 cm at baseline, 0.04 +/- 0.01 cm/year slope, p < 0.001). The regurgitant orifice area also increased (0.12 +/- 0.14 cm2 at baseline, 0.01 +/- 0.01 cm2/year, p = 0.05). Changes in regurgitant orifice area were related to changes in left ventricular end-diastolic dimension (p < 0.001). There were no significant changes in left ventricular chamber dimensions, volumes, and regurgitant volume over time in this cohort. Increases in jet width and orifice area occurred in patients with all degrees of baseline disease severity, with bicuspid or tricuspid leaflet morphology, and with male or female sex. In this prospective study of chronic aortic regurgitation, both jet width and Doppler-derived regurgitant orifice area increased over time. These findings suggest that one factor in the progression of chronic aortic regurgitation is enlargement of the orifice.

Aortic flow velocity patterns in chronic aortic regurgitation: implications for Doppler echocardiography.

Aortic regurgitation is associated with retrograde diastolic flow in the aorta. Echocardiographic quantitative analysis of the magnitude of the flow reversal is believed to provide an estimate of severity of regurgitant disease despite variations in flow profiles. The purpose of this study was to evaluate the uniformity of flow patterns in the aorta of patients with aortic regurgitation and to investigate the relationship between these profiles and the echocardiographic estimates of flow reversal. Seventeen patients with chronic aortic regurgitation underwent cine-phase magnetic resonance imaging in an axial section through the ascending and descending aorta. The regurgitant fraction in the ascending aorta 4 cm above the aortic valve and the descending aorta were calculated from the velocity maps. These results were compared with data from nine individual sample volumes in the ascending and descending aorta. The magnetic resonance ascending aortic regurgitant fraction was compared with Doppler echocardiographic descending aortic flow velocity patterns. The descending aortic regurgitant fraction correlated only weakly with the ascending aortic regurgitant fraction (descending aortic regurgitant fraction = 0.62% ascending aortic regurgitant fraction + 0.04%; r = 0.75; p < 0.001). Regurgitant proportions in all sample volumes in the descending aorta, but not in the ascending aorta, were significantly related to the ascending aortic regurgitant fraction. The best descending aortic Doppler echocardiographic parameter for predicting ascending aortic regurgitant fraction was the end-diastolic velocity (end-diastolic velocity = 32.2 cm/sec. ascending aortic regurgitant fraction + 1.4 cm/sec; r = 0.94; p < 0.001). Pulsedwave Doppler sampling of descending aortic flow reflects severity of aortic regurgitant disease, in part the result of more uniform blood-velocity profiles in the descending aorta compared with the ascending aorta. The Doppler end-diastolic velocity in the descending aorta is a useful parameter of severity of aortic regurgitation.

Preoperative prediction of prosthetic aortic valve annulus diameter by two-dimensional echocardiography.

Echocardiography may allow preoperative selection of appropriately sized aortic homograft valves. This study compared measurement of aortic annulus diameter from the preoperative transthoracic two-dimensional echocardiogram with prosthetic valve annulus diameter in 178 consecutive patients under-going primary aortic valve replacement. Aortic annulus diameter was measured independently from the two-dimensional parasternal long axis view by two experienced observers blinded to the size of valve implanted. Mean annulus diameter from three end-diastolic frames was recorded. Of the 178 patients, 124 (70%) of Observer 1 measurements and 102 (57%) of Observer 2 measurements were within 2mm of valve annulus diameter (p < 0.0001 for both observers). Six percent of Observer 1 measurements and 12% of Observer 2 measurements were more than 4mm away from valve annulus diameter. The echocardiographic prediction of valve size corresponded to actual prosthetic valve annulus diameter in 69 patients (39%) for Observer 1 and 60 patients (34%) for Observer 2. The percentages of echocardiographic measurements within two millimeter of valve annulus diameter were significantly different for the two observers (p < 0.05). The percentages of echocardiographic measurements within two millimeter of valve annulus diameter in 39 patients without significant aortic valve calcification were not significantly different from the remaining 139 patients with calcified valves. The interobserver coefficient of variation was 6.2% and the intraobserver coefficient of variation was 4.3%. Although preoperative measurement of aortic annulus diameter from transthoracic echocardiography approximates prosthetic valve annulus diameter in the majority of patients undergoing primary aortic valve replacement, a significant minority of estimates may be inaccurate, even in the absence of heavy calcification.(ABSTRACT TRUNCATED AT 250 WORDS)

Avoiding drug problems. The safety of drugs for supraventricular tachycardia.

To minimize drug problems in the treatment of supraventricular tachycardias, it is important to understand the spectrum of adverse events and to identify patients at high risk for these problems. Adverse cardiac and non-cardiac effects are associated, to varying degrees, with currently available antiarrhythmics. Cardiac adverse events include the development of rhythm disturbances, such as ventricular tachycardia or torsades des pointes, may result in syncope or death. In a meta-analysis of six randomized trials of quinidine vs placebo for atrial fibrillation, 1.8% of quinidine-treated patients died as opposed to 0.3% of placebo-treated patients. This increase in mortality was also noted in patients enrolled in the Stroke Prevention in Atrial Fibrillation Trial who were treated with type I antiarrhythmics. This increase in mortality was confined primarily to patients with a history of congestive heart failure. In a randomized trial of propafenone and sotalol for the treatment of atrial fibrillation, two out of 50 patients receiving sotalol died suddenly, one of whom had hypokalaemia-associated torsades des pointes. No patient receiving propafenone died during this trial. In a meta-analysis of propafenone's effect in treating supraventricular tachyarrhythmias in over 3100 adult patients, overall mortality was extremely low at 0.3%. Structural heart disease may increase the risk of antiarrhythmic agents. During inpatient drug trials in patients treated for atrial fibrillation at Brigham and Women's Hospital, adverse cardiac events, primarily bradyarrhythmias, occurred in up to 15% of the patients. Older age and prior myocardial infarction were associated with an increased risk of adverse events. Adverse drug problems may be minimized by careful attention to electrolytes, medications, concomitant medical illnesses, and underlying conduction disease. Careful monitoring of patients during initiation of therapy, especially those patients with ischaemic heart disease, congestive heart failure, and who are older, may minimize drug-related problems.

Clinical challenge. I: Control of recurrent symptomatic atrial fibrillation.

Control of recurrent symptomatic atrial fibrillation should be directed at: (1) alleviation of symptoms associated with atrial fibrillation and (2) reduction of the risk of embolization. Approximately 50-60% of patients treated with conventional agents such as quinidine will develop recurrent atrial fibrillation in the first year of treatment. Because of this relapse rate and the side effects associated with quinidine and other type Ia antiarrhythmic agents, it is important to investigate the efficacy and safety of newer antiarrhythmic agents such as propafenone and sotalol. In our institution, 100 patients with recurrent symptomatic atrial fibrillation who had failed therapy with at least one type Ia agent were randomized to propafenone or sotalol. Propafenone and sotalol were equally effective in preventing recurrent atrial fibrillation at 6 and 12 months after onset of therapy independent of arrhythmia pattern or left atrial size. Both agents were well tolerated with only 10% of patients discontinuing therapy due to side effects. We combined data from this randomized study with a stepped care trial of propafenone and sotalol to examine risk factors for the development of recurrent atrial fibrillation. In patients treated with propafenone or sotalol, there was no significant difference in response to therapy based on age, gender, or aetiology of heart disease. Patients with dual-chamber pacing had improved maintenance of sinus rhythm as compared to those individuals without pacemakers. Left atrial size did not significantly influence the likelihood of maintaining sinus rhythm in these trials. Pharmacological management of the patient with recurrent symptomatic atrial fibrillation remains a difficult problem. Patient symptom severity and the clinical profile should be examined prior to instituting antiarrhythmic therapy in any given patient. These studies indicate that propafenone and sotalol are equally effective when used to maintain sinus rhythm in our population. As more data on the merits and risks of antiarrhythmic therapy for the treatment of atrial fibrillation become available, the role of propafenone and sotalol in the treatment of this disorder will be better understood.

Assessment of the efficacy and safety of antiarrhythmic therapy for chronic atrial fibrillation: observations on the role of trial design and implications of drug-related mortality.

The findings in clinical trials of antiarrhythmic drug efficacy and safety are frequently difficult to compare, since study design often has an important effect on trial outcome. To explore this problem further, we compared three designs--randomized control, nonrandomized control, and uncontrolled--collectively enrolling 2415 patients in 21 trials reporting on the role of quinidine in the prevention of chronic atrial fibrillation. The proportion of patients remaining in sinus rhythm at 3, 6, and 12 months after cardioversion was calculated by means of Kaplan-Meier techniques, and the data were pooled for each trial design. For the randomized control trials the difference in the absolute percentage of patients remaining in sinus rhythm in the quinidine and control groups was 24% at each of the three follow-up intervals. Contrary to findings in the randomized control trials, the magnitude of the treatment benefit in nonrandomized trials was smaller and declined markedly over time. The percentage of patients remaining in sinus rhythm in the uncontrolled trials was intermediate to the percentages in the other two trial designs. When the data from all three trial designs were pooled, the crude mortality rate was 2.0% in quinidine-treated patients and 0.6% in control patients. Sudden cardiac death or ventricular fibrillation was the cause of death in 13 of 19 patients for whom the cause of death was known, highlighting the potential risk of quinidine-induced proarrhythmia. Although quinidine is effective in maintaining sinus rhythm, estimates of the treatment effect vary among trial types.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of supraventricular arrhythmias after coronary artery bypass surgery. A meta-analysis of randomized control trials.

This meta-analysis was performed to determine the efficacy of digoxin, verapamil, and beta-adrenoceptor blockers as prophylaxis against supraventricular arrhythmias (SVAs) after coronary artery bypass graft surgery (CABG). Randomized control trials were included if the electrocardiographic monitoring technique was clearly defined and extended through at least the first 3 postoperative days. Twenty-four of 69 identified studies were included in the final analysis. A summary odds ratio (OR) of the likelihood of developing SVAs after CABG in the treatment versus control groups was calculated. The pooled mean ventricular rate during SVA in patients who developed such an arrhythmia was also calculated. Neither digoxin nor verapamil reduced the likelihood of SVAs after CABG (digoxin: OR = 0.97, 95% confidence interval [CI] = 0.62-1.49; verapamil: OR = 0.91, CI = 0.57-1.46). The likelihood of developing an SVA in patients treated with beta-blockers was markedly decreased compared with controls (OR = 0.28, CI = 0.21-0.36). The pooled ventricular rate when SVAs did occur was significantly lower in each of the treatment groups. Prophylactic beta-adrenoceptor blockers had a protective effect against the development of SVAs in a select population of patients undergoing CABG. No such beneficial effect was demonstrated for digoxin or verapamil. All three classes of agents reduced the ventricular rate in patients who developed the arrhythmia, although the ventricular rate reduction was not clinically optimal.

Influence of aortic pressure on effective regurgitant orifice area in aortic regurgitation.

BACKGROUND: The regurgitant volume in aortic regurgitation is determined by the diastolic filling period, the pressure gradient between the left ventricle and aorta, and the hemodynamic size of the regurgitant orifice area. METHODS AND RESULTS: To test the hypothesis that the aortic regurgitant orifice area is related to aortic pressure and aortic root size, 16 fresh calf heart and aorta specimens were studied in vitro using a continuous-flow system over a range of aortic pressures. Regurgitant orifice areas were calculated as the ratio of flow divided by peak velocity through the valve measured by image-guided continuous-wave Doppler, and aortic root areas were measured by two-dimensional echocardiography. When the defect was created at the edge of the noncoronary leaflet (n = 10), regurgitant orifice area gradually increased 51 +/- 33% when aortic pressure was increased from approximately 40 to 152 cm of water (29.6 to 112.5 mm Hg) (p less than 0.0001). Similarly, the aortic root size increased 82 +/- 29% when the defect was created at the leaflet edge (p less than 0.0001). In contrast, when defects were created at the center of the noncoronary leaflet (n = 6), only a small increase in regurgitant orifice area (9 +/- 7%) was observed with increasing pressure (p = 0.043). The aortic root area remained strongly pressure dependent in specimens with defects at leaflet centers (p less than 0.0001). CONCLUSIONS: The aortic regurgitant orifice area is dependent on both aortic pressure and the nature of the defect in the valve. Because not all regurgitant aortic valves are alike, further study of the nature of the regurgitant orifice area in humans may allow identification of patients who would benefit most from aggressive pharmacological therapy.

Risk factors for the development of recurrent atrial fibrillation: role of pacing and clinical variables.

Atrial fibrillation recurs in many patients treated with antiarrhythmic therapy to maintain sinus rhythm. From March 1985 to August 1991, 214 patients with recurrent symptomatic chronic or paroxysmal atrial fibrillation for which conventional antiarrhythmic agents had failed were treated with propafenone or sotalol. Baseline demographic data including the presence of pacing therapy were collected. Life-table estimates of the duration of freedom from atrial fibrillation were constructed on the basis of pacemaker status. Of 214 patients, 26 (12.1%) had pacing therapy. Patients with dual-chamber pacing were more likely to remain in sinus rhythm at 6 months (80%) than were patients with ventricular pacing (40%) or patients without pacing therapy (55%) (p = 0.002). A Cox univariate regression analysis demonstrated that dual-chamber pacing in contrast to ventricular pacing or no pacing was associated with a lower risk of recurrent atrial fibrillation. Clinical parameters such as age, gender, left atrial size, fibrillation pattern, drug assignment, ejection fraction, and underlying cardiac disease did not alter the risk of recurrent atrial fibrillation. Dual-chamber pacing was associated with a decreased likelihood of recurrent atrial fibrillation even after adjustment for other clinical covariates in a multivariate model (p = 0.04). In patients with recurrent atrial fibrillation treated with propafenone or sotalol, dual-chamber pacing improved maintenance of sinus rhythm.

Influence of jet impingement on color Doppler parameters of aortic regurgitation.

In vitro studies have demonstrated that the characteristics of a color Doppler jet are influenced by a number of factors including jet eccentricity and jet impingement. To explore the relationship of a jet impingement and aortic regurgitant color Doppler jet parameters, jet area, width, and length were measured from apical echocardiographic views of 84 patients 4 +/- 11 days prior to catheterization and compared to angiographic grade. An impinging color jet contacted the interventricular septum or mitral valve beneath the aortic valve in the imaging plane and a nonimpinging jet did not contact the septum or mitral valve in the imaging plane. As expected, the percentage of patients with impinging jets increased with aortic regurgitation angiographic grade. Neither left ventricular chamber dimensions nor the presence of an aortic prosthesis significantly influenced the color Doppler variables. For a given angiographic grade of aortic regurgitation, impinging jets were associated with larger color Doppler jet widths (P less than 0.05) and areas (P = 0.001) than nonimpinging jets. The color Doppler area and length increased significantly with angiographic grade for nonimpinging jets (P less than 0.05) but not for impinging jets. Impinging jets are associated with larger color Doppler widths and areas than nonimpinging jets for a given grade of aortic regurgitation, possibly because of the effect of jet deflection toward an adjacent wall. Jet impinging should be considered when using color Doppler techniques to evaluate aortic regurgitation.