Clinical diagnosis of aortic-valve disease

Non-invasive and invasive evaluation of aortic valve area in 100 patients with severe aortic valve stenosis: comparison of cardiac computed tomography with ECHO (transesophageal/transthoracic) and catheter examination

BACKGROUND

Current guidelines place emphasis on the determination of aortic valve area (AVA) for defining an appropriate treatment strategy. Invasive and non-invasive modalities are used to perform planimetric [transesophageal echocardiography (TEE) and cardiac multidetector computed tomography (MDCT)] and calculated [catheter examination (CE), transthoracic echocardiography (TTE)] AVA measurements.

PURPOSE AND METHODS

We investigated 100 patients admitted to evaluate the AVA using cardiac MDCT (CT), TEE/TTE as well as invasive CE.

RESULTS

In all 100 patients we calculated a mean AVA of 0.79±0.29cm(2) (female 50/100, 0.70±0.19cm(2), male 0.9±0.21cm(2)) determined by all investigated examinations (mean±SEM). AVA measurements determined by CT were significantly greater (0.86±0.25cm(2)) than those determined by CE: 0.75±0.18cm(2), p=0.01. Echocardiographically determined AVA was comparable to CE (statistically not significant). Similar results were seen in all patients regardless of gender, presence of atrial fibrillation, and heart rate. We calculated a mean AVA for each patient and evaluated the variance of the AVA determined through investigated specific examinations as the bias. Overall, we found for CT 0.13±0.1cm(2), CE 0.13±0.11cm(2), TEE 0.16±0.09cm(2), and for TTE 0.16±0.08cm(2) a specific statistical non-significant variance. On subgroups: sinus rhythm, atrial fibrillation, females, males or combination, we found no further significant relevance for the specific variance.

CONCLUSION

Our data suggest the feasibility of cardiac MDCT to evaluate the correct AVA regardless of rhythm, heart rate, and sex. The planimetric concept to determine the AVA with CT displaces the "gold-standard" CE with respect to elucidating the potencies for complications, i.e. cerebral stroke. Regardless of CT's accessing of AVA measurement the TTE examination should remain the primary method of screening for aortic valve pathologies.

Effects of valve dysfunction on Doppler Tei index

BACKGROUND

Recently proposed Doppler Tei index, defined as the sum of isovolumic contraction time or mitral valve closure to aortic valve opening time and isovolumic relaxation time or aortic valve closure to mitral valve opening time divided by ejection time, is a simple measure which enables noninvasive estimation of combined systolic and diastolic function and prediction of patients' prognosis. However, effects of valve dysfunction on Tei index have not been investigated. This study was designed to compare Tei index before and after surgical valve replacement or repair to evaluate effects of valve dysfunction on Tei index.

METHODS

Participants consisted of 76 consecutive patients with aortic or mitral valve surgery (26 patients with aortic stenosis [AS], 16 with aortic regurgitation, 17 with mitral stenosis, and 17 with mitral regurgitation). Doppler Tei index was evaluated before and after the surgery by obtaining (a-b)/b, where a is the interval between the cessation and onset of Doppler mitral filling flow and b is the aortic flow ejection time.

RESULTS

Tei index significantly increased after surgery in patients with AS (0.38 +/- 0.07 to 0.49 +/- 0.06, P <.001), aortic regurgitation (0.60 +/- 0.20 to 0.70 +/- 0.18, P <.01), mitral stenosis (0.34 +/- 0.03 to 0.39 +/- 0.04, P <.01), and decreased with no significance in mitral regurgitation (0.50 +/- 0.03 to 0.46 +/- 0.03). Percent change in Tei index after valve surgery was maximal in patients with AS (27 +/- 6 vs 17 +/- 2 vs 16 +/- 6 vs -9% +/- 6%, AS vs aortic regurgitation vs mitral stenosis vs mitral regurgitation, P <.001).

CONCLUSION

Tei index significantly changes after valve surgery especially in patients with AS. Considerations for the effects of valve dysfunction on Tei index are required for its application to evaluate ventricular function in patients with valve disease.

Hemodynamic and angiographic evaluation of aortic regurgitation 8 and 27 months after aortic valve replacement

Eighteen patients with chronic aortic insufficiency were evaluated hemodynamically and angiographically 8 months after aortic valve replacement. Both the pulmonary artery diastolic pressure and the left ventricular end-diastolic volume decreased significantly (p less than 0.001), but the mean ejection fraction and the cardiac output remained identically lowered, though some individual cases showed improvement. The relative reduction in end-diastolic volume correlated only with the preoperative ejection (p less than 0.05) and regurgitation fractions (p less than 0.02). In the 10 patients whose left ventricular volume remained high or ejection fraction low, a second evaluation was performed 27 months after surgery. The left ventricular end-diastolic volume was significantly lowered (from 151 to 120 ml/m2, p less than 0.05) back to normal in five cases. The systolic and diastolic ventricular shape returned to normal. Cardiac index and ejection fraction were unchanged. These results show a marked improvement a few months after aortic valve replacement, with a further improvement several months later, as shown mainly by the decrease of left ventricular end-diastolic volume and the return to normal of left ventricular cavity shape. However, in most cases, the ejection fraction remained at its preoperative valve, suggesting that surgery should be performed early, before myocardial deterioration appears.

Mechanisms of angina in aortic stenosis

The pathophysiology of cardiac pain in pure aortic stenosis has primarily been ascribed to an augmented left ventricular demand outstripping energy supply. This report provides evidence that not only is the energy demand increased but the supply in terms of coronary vascular reserve may be impaired, particularly in response to stress. Hemodynamic and coronary circulatory changes were studied in 18 patients with aortic stenosis during standard isoproterenol infusion. It was not possible to differentiate any patient with or without angina pectoris or patients with or without coronary artery disease on a basis of change in any measure of left ventricular dynamics. On the other hand, differences did occur in the mechanisms of energy delivery during isoproterenol stress: (1) In group A (aortic stenosis without angina or coronary artery disease), coronary flow increased normally, myocardial oxygen extraction decreased, and myocardial lactate production occurred in only one of seven patients. This suggested that energy supply was, generally, adequate to demand. (2) In group B (critical aortic stenosis with angina but no coronary disease), coronary flow rose insignificantly, myocardial oxygen extraction actually increased in three of five patients, and abnormal glycolysis occurred in all patients. This suggested that little or no reserve for increased coronary flow existed and that compensatory mechanisms had to be summoned. (3) In group C (aortic stenosis with angina and coronary artery disease), coronary flow rose normally, myocardial oxygen extraction decreased normally, but abnormal lactate metabolism occurred in most patients. This suggested adequate overall coronary reserve but evidence of regional ischemia.