Changes in left ventricular systolic performance immediately after percutaneous aortic balloon valvuloplasty

Balloon aortic valvuloplasty in adults: failure of procedure to improve long-term survival

OBJECTIVES

This study sought to determine the long-term outcome of adult patients undergoing percutaneous balloon aortic valvuloplasty.

BACKGROUND

Percutaneous balloon aortic valvuloplasty has been offered as an alternative to aortic valve replacement for selected patients with valvular aortic stenosis. Although balloon aortic valvuloplasty produces an immediate reduction in the transvalvular aortic gradient, a high incidence of restenosis frequently leads to recurrent symptoms. Therefore, it is unclear whether balloon aortic valvuloplasty impacts on the long-term outcome of these patients.

METHODS

Clinical, hemodynamic and echocardiographic data were collected at baseline in 165 patients undergoing balloon aortic valvuloplasty and examined for their ability to predict long-term outcome.

RESULTS

The median duration follow-up was 3.9 years (range 1 to 6). Ninety-nine percent follow-up was achieved. During this 6-year period, 152 patients (93%) died or underwent aortic valve replacement, and 99 (60%) died of cardiac-related causes. The probability of event-free survival (freedom from death, aortic valve replacement or repeat balloon aortic valvuloplasty) 1, 2 and 3 years after valvuloplasty was 40%, 19% and 6%, respectively. In contrast, the probability of survival 3 years after balloon aortic valvuloplasty in a subset of 42 patients who underwent subsequent aortic valve replacement was 84%. Survival after aortic valvuloplasty was poor regardless of the presenting symptom, but patients with New York Heart Association functional class IV congestive heart failure had events earliest. Univariable predictors of decreased event-free survival were younger age, advanced congestive heart failure symptoms, lower ejection fraction, elevated left ventricular end-diastolic pressure, presence of coronary artery disease and increased left ventricular internal diastolic diameter. Stepwise multivariable logistic regression analysis found that only younger age and a lower left ventricular ejection fraction contributed independent adverse prognostic information (chi-square 14.89, p = 0.0006).

CONCLUSIONS

Long-term event-free and actuarial survival after balloon aortic valvuloplasty is dismal and resembles the natural history of untreated aortic stenosis. Aortic valve replacement may be performed in selected subjects with good results. However, the prognosis for the remainder of patients who are not candidates for aortic valve replacement is particularly poor.

Pressure-volume loops: a dynamic approach to the assessment of ventricular function

Analysis of ventricular function in terms of pressure-volume or pressure-dimension relationships allows global and regional ventricular dynamics to be fully analyzed. In addition, this approach allows the relationships between muscle function (contractility, stiffness, potential energy) and pump function (stroke volume, stroke work) to be determined and predicted. Alterations in ventricular loading conditions can also be examined in terms of muscle and pump function. However, this analysis is more complex than initially thought and considerable care must be taken especially when regional ischemia is concerned. Moreover, some of the early assumptions have been disproved and conclusions can only be drawn from studies in which full assessment of changes in pressure and dimensions is available.

Ejection load changes in aortic stenosis. Observations made after balloon aortic valvuloplasty

To investigate complementarity and competitiveness between the intrinsic and extrinsic components of the total left ventricular systolic load, hemodynamic data from 18 elderly subjects with severe aortic stenosis were analyzed before and after balloon dilation of the stenosed aortic valve. Multisensor micromanometric pressure measurements allowed calculation (simplified Bernoulli equation) of the ejection velocity and aortic input impedance spectra. Despite a 32% increase in the aortic valve area (from 0.56 +/- 0.04 to 0.74 +/- 0.05 cm2 [mean +/- SEM], p < 0.01), the peak left ventricular systolic pressure fell by only 12% (from 189 +/- 10 to 167 +/- 8 mm Hg, p < 0.01). This was accompanied by an increase in the impedance at the same cardiac output. In a subset of patients (n = 9) in whom the peak aortic systolic pressure rose after valvuloplasty (from 115 +/- 10 to 128 +/- 12 mm Hg, p < 0.01), a 40% increase in the aortic valve area was accompanied by a marked increase in the aortic input impedance. In this subset, the steady component of the aortic input impedance increased by 24% (from 960 +/- 96 to 1,188 +/- 134 dyne.sec/ml, p < 0.05), and the characteristic impedance increased by 25% (from 106 +/- 13 to 132 +/- 19 dyne.sec/ml, p < 0.05). Because of an increased aortic impedance acutely following the procedure, the total left ventricular systolic load after balloon dilation of the stenotic valve was only slightly decreased despite a significant increase in aortic valve area. This represents an example of complementarity and competitiveness between the intrinsic and extrinsic components of the total systolic ventricular load. It may explain why improvement in left ventricular performance may be modest acutely following balloon aortic valvuloplasty.

Demonstration of postvalvuloplasty hemodynamic improvement in aortic stenosis based on Doppler measurement of valvular resistance

It was recently suggested that valvular resistance, defined as the pressure gradient/flow rate ratio, may better depict the hemodynamic impairment in aortic stenosis than does valve area. The relation between aortic valve resistance and left ventricular mechanics was studied with Doppler echocardiography in 13 patients (mean age 85 years) with severe aortic stenosis who underwent percutaneous balloon valvuloplasty. The Doppler-estimated peak valvular resistance, defined as the ratio of peak transvalvular pressure gradient to peak valvular flow rate, decreased from 510 +/- 190 dynes.s.cm-5 before valvuloplasty to 300 +/- 110 dynes.s.cm-5 after the procedure (p = 0.0001). There was a close linear relation between valvular resistance measured at catheterization and Doppler-derived peak valvular resistance (r = 0.91). After valvuloplasty, left ventricular ejection fraction increased from 53 +/- 13% to 62 +/- 11% (p = 0.0001). The percent increase in ejection fraction was linearly related to the percent decrease in end-systolic wall stress (r = 0.56), which was in turn related to the percent decrease in peak valvular resistance (r = 0.75). No such linear relation existed between the percent changes in valve area and those in end-systolic wall stress. In conclusion, hemodynamic improvement after valvuloplasty is more closely related to changes in valvular resistance than to changes in valvular area. It is suggested that valvular resistance can be estimated accurately by Doppler echocardiography with use of a simple method and should be a primary consideration in assessing the hemodynamics of aortic stenosis.

Left ventricular volumes and function immediately after balloon mitral valvoplasty

To evaluate acute changes in left ventricular volumes and function immediately after successful percutaneous balloon mitral valvoplasty, twenty young patients with isolated rheumatic mitral stenosis (male 9, female 11, mean age 22 +/- 6 years) were studied. The area of the orifice of the mitral valve following valvoplasty, increased from 0.97 +/- 0.27 cm2 to 2.46 +/- 0.75 cm2 (P less than 0.001). No significant change was observed in left ventricular end-diastolic volumes (117 +/- 27 ml to 119 +/- 29 ml, P greater than 0.10), end-systolic volumes (51 +/- 21 ml to 50 +/- 20 ml, P greater than 0.10), ejection fraction (0.57 +/- 0.10 to 0.58 +/- 0.10, P greater than 0.10) and left ventricular meridian wall stress (68 +/- 20.10(3) dynes/cm2 to 65 +/- 14, P greater than 0.10) immediately after valvoplasty. There was no acute change in heart rate, left ventricular end-diastolic pressure, cardiac index and grade of mitral regurgitation. Patients with depressed left ventricular ejection fraction (less than or equal to 0.55, n = 10) and those with normal ejection fraction (greater than 0.55, n = 10) had similar baseline left ventricular end-diastolic volumes and showed no significant change in volumes and ejection fraction after the procedure, although the former group had a greater orificial area after valvoplasty (P less than 0.05). We conclude that an acute increase in the orifice of the mitral valve in patients with rheumatic mitral stenosis is not associated with any significant change in left ventricular volumes and function.