• Non ci sono risultati.

Assessment of Diastolic Function in Heart Failure and Atrial Fibrillation

N/A
N/A
Protected

Academic year: 2021

Condividi "Assessment of Diastolic Function in Heart Failure and Atrial Fibrillation"

Copied!
7
0
0

Testo completo

(1)

Fibrillation

S. CARERJ, S. RAFFA, C. ZITO

In the past three decades, Doppler echocardiography has emerged as a non- invasive alternative to cardiac catheterisation for evaluating haemodynamic variables [1]. A well-performed Doppler examination is able to provide as accurate data as conventional cardiac catheterisation does.

Diastolic function of the left ventricle (LV) plays a relevant role in pro- ducing the signs and symptoms of heart failure (HF) in cardiac diseases, the end result of which is the elevation of left ventricular pressure per unit vol- ume of blood entering the LV [2–5]. This elevated filling pressure increases left atrial pressure, which is reflected back to the pulmonary circulation and causes symptoms of shortness of breath and signs of pulmonary congestion.

Because of the complexity of the multiple interrelated events that comprise diastolic filling of the heart, assessment of LV diastolic function was in the past limited to the catheterisation laboratory, where complex measurements of pressure–volume relations and rates of decrease in pressure from high- fidelity pressure curves were used [6].

It has been speculated that Doppler echocardiography could be used to assess diastolic filling and function of the LV non-invasively [7, 8].

Kitabatake et al. [9] in 1982 described the different flow velocity curves that occur in different disease states from Doppler interrogation of transmitral flow. Multiple investigations in both animals and humans followed and pro- vided insight into the interpretation of these flow velocity patterns [10, 11].

The mitral flow velocity curves can be viewed as determined by the relative driving pressure across the mitral valve from the left atrium to the LV. There is an initial rapid acceleration of flow as left ventricular pressure drops rapidly below left atrial pressure during ventricular relaxation (measured as the E wave velocity). As the LV fills in early diastole, there is a rise in pres-

Division of Cardiology, University of Messina, Italy

(2)

sure that exceeds the left atrial pressure, causing a deceleration of flow. The rate of deceleration of flow is measured as the mitral E wave deceleration time and is dependent mainly upon the effective operating compliance of the LV. During mid-diastole there is equilibration of left ventricular and left atri- al pressures, with a low velocity of forward flow as a result of inertial forces.

Finally, at atrial contraction there is a re-acceleration of transmitral flow as left atrial pressure rises above left ventricular pressure (measured as the A wave velocity). These flow velocity curves are dependent on multiple intrin- sic factors that include the rate of left ventricular relaxation and elastic recoil (diastolic suction), left atrial and left ventricular compliance, and left atrial pressure, as well as varying patient conditions such as load, age, and heart rate [10, 11].

It has already been shown in experimental models of HF [12] that there is also a progression of abnormal diastolic patterns that occurs over time with cardiac diseases. In the early stage of dysfunction, impaired relaxation of the LV dominates, which decreases early diastolic filling although filling pres- sures remain normal in the rest state. This is reflected by a decrease in the initial E wave velocity, prolongation of E wave deceleration time, and increased proportion of filling due to atrial contraction. With disease pro- gression, left atrial pressure rises, which increases the driving pressure across the mitral valve. This is accompanied by a gradual increase in E wave velocity and a decrease in effective operating compliance of the LV, which shortens the mitral E wave deceleration time. In advanced stages of disease, there will be even higher pressures, a higher E/A ratio, and a very abbreviat- ed mitral deceleration time. This concept of a progression of the mitral flow velocity curves with worsening disease has a clinical application: the prog- nosis of patients with either dilated or infiltrative cardiomyopathy is indicat- ed by a short mitral deceleration time, with values below 140 ms indicating a poor outcome, independently of the degree of systolic dysfunction [13, 14].

Furthermore, non-invasive assessment of left ventricular filling pressures in HF patients would be of great value in assessing their degree of left ventricu- lar dysfunction and monitoring the effect of unloading therapies. Previous studies have shown that this can be estimated by combining various Doppler echocardiographic variables [10, 15–17]. Patients with atrial fibrillation (AF) have, however, been excluded from these studies, limiting the applicability of such estimates to patients in sinus rhythm.

It has been shown that in patients with HF and sinus rhythm elevated left atrial pressures can compensate for delayed left ventricular relaxation, thus increasing early diastolic mitral flow velocity and its deceleration and decreasing isovolumic relaxation time. High left atrial pressure before atrial contraction together with a stiff LV shortens and reduces mitral flow velocity wave at atrial contraction. This leads to the so-called pseudo-normal and

(3)

restrictive patterns that in HF patients are reliable indexes of elevated left ventricular filling pressures. Pulmonary venous flow in sinus rhy thm patients shows a triphasic pattern which is predominantly related to left atri- al function and reflects the oscillations of left atrial pressures [18]. Thus, the systolic forward flow velocity is determined by the combined backward effect of the decrease in left atrial pressure, due to both left atrial relaxation and mitral annulus descent, and the forward propagation of systolic right ventricular pressure [19]. The diastolic forward flow velocity, which occurs when the mitral valve is open and the left atrium behaves as a passive con- duit, slightly follows and is closely related to early diastolic mitral flow veloc- ity. The reverse diastolic flow velocity wave is determined by atrial contrac- tion and its duration depends mainly on left ventricular compliance. In patients with HF and sinus rhythm, when the left atrial pressure is high (and left atrial compliance is reduced) the systolic flow velocity is blunted; the diastolic forward flow velocity is high and its deceleration is rapid; the reverse flow is prolonged and its duration exceeds that of forward mitral flow at atrial contraction.

Unfortunately, approximately 20% of patients with chronic HF have AF [20, 21]. When AF is present, the loss of atrial contraction and of ventricular rate control affects both mitral and pulmonary venous flow and the relation- ship between Doppler variables and left ventricular filling pressure becomes more complicated. When AF occurs, the active atrial contraction is lost, so that the whole blood volume filling the LV is detected in a monophasic E wave. At the same time Doppler recording of pulmonary venous flow shows a loss of the late diastolic reverse flow. Loss of the active left atrial relaxation causes the disappearance of the first component of the systolic forward flow velocity. Besides these effects on left ventricular and atrial filling due to the loss of an active atrial contraction, irregular cardiac cycle lengths produce marked beat-to-beat variations in both mitral and pulmonary venous flow velocities.

Despite all these differences between Doppler echocardiographic findings in patients with sinus rhythm and AF, a relatively accurate estimation of pul- monary capillary wedge pressure (PCWP) can be achieved in HF patients who are in AF. In particular, in patients with AF, indexes of early left ventric- ular diastolic filling, i.e. isovolumic relaxation time, deceleration time, and deceleration rate, and the systolic fraction of pulmonary venous flow are almost as strongly correlated with PCWP as they are in patients with sinus rhythm [22, 23]. Temporelli et al. [24] have recently found that a value of 120 ms in E wave deceleration time seems to be the best cut-off point in predict- ing high values of PCWP in HF patients with AF, the sensitivity and specifici- ty of a mitral E wave deceleration time below 120 ms in predicting PCWP above 20 mmHg being 100% and 96%, respectively.

(4)

AF is characterised by an irregular heart rate that produces beat-to-beat variations in contractility, preload, after-load, and mitral regurgitation, which leads to increased variability in Doppler measurements. To minimise this problem it would be preferable to investigate patients when they are receiving optimal medical therapy including medications that are able to reduce sufficiently (and synchronise as much as possible) their ventricular heart rate. Moreover, short cardiac cycles (< 600 ms) should not be analysed because they are often associated with fusion of pulmonary venous flow waves. The optimal number of beats to be analysed and averaged for Doppler measurements of diastolic function in AF should be approximately three times that necessary in sinus rhythm, i.e. from 5 to 10.

Problems related to variability of haemodynamic conditions in HF patients with AF may constitute a limit of flow Doppler; furthermore, to obtain meaningful data, a strict and time-consuming methodology must be followed, which may limit the everyday application of this parameters in a busy clinical practice.

In order to limit the load dependence of flow Doppler measurements on left ventricular diastolic function, new methods have recently been intro- duced. Nagueh et al. [25] found that peak acceleration of the E wave (PkAcc), isovolumic relaxation time, deceleration time of the E wave, and the ratio of E velocity to propagation velocity (E/Vp) were strongly related to left ven- tricular filling pressure. In particular, the velocity of propagation of the early inflow from the LV base to the apex (Vp), determined using colour M-mode, correlated well with the time constant of isovolumetric left ventricular relax- ation (τ) [26]. In patients with abnormal left ventricular relaxation and ele- vated left ventricular end-diastolic pressure, filling flow propagation is rapidly attenuated in spite of the increased early transmitral velocity.

Therefore, as the severity of HF increases, the E/Vp also increases and may be a more sensitive index than E velocity or Vp alone. Recently Oyama et al.

[27] found that a cut-off value of E/Vp of 1.7 was able to predict with accept- able accuracy the presence of high PCWP (> 15 mmHg) in HF patients with AF.

Tissue Doppler imaging has recently become a common tool of modern ultrasound systems. This allows the recording of myocardial contraction and relaxation velocities. The early diastolic mitral annular velocity (Ea) has been shown to be a relatively load-independent measure of myocardial relaxation in patients with cardiac disease [28]. When tissue Doppler imag- ing is combined with pulsed Doppler transmitral flow in early diastole (E), the resultant E/Ea ratio has been correlated with left ventricular filling pres- sure measured invasively in patients with sinus rhythm [29]. E/Ea values above 15 have been shown to be highly predictive (sensitivity 92%, specifici- ty 90%) of a PCWP greater than 15 mmHg in patients with depressed ejec-

(5)

tion fraction and sinus rhythm [30]. In conclusion, Doppler echocardiogra- phy is now well accepted as a reliable and reproducible method for assessing diastolic function in various cardiac diseases. Several studies have demon- strated that left ventricular pressure and mean PCWP can be estimated from variables of mitral and pulmonary venous flow. In particular, an excellent inverse correlation has been found between the deceleration time of trans- mitral E wave and PCWP in patients with severe left ventricular dysfunction and sinus rhythm. In the case of HF patients with AF, however, few data have been published so far. The presence of irregular rhythm associated with high variability of haemodynamic conditions and absence of atrial contraction constitute an obstacle to the accurate evaluation of left ventricular diastolic function by means of flow Doppler imaging. Tissue Doppler imaging could be of great utility in this particular clinical setting thanks to its relative load- independence. Further clinical studies are needed in order to assess the value of tissue Doppler variables in estimating left ventricular filling pressures and to compare them to flow Doppler parameters in HF patients with AF.

References

1. Nishimura RA, Tajik AJ (1994) Quantitative hemodynamics by Doppler echocar- diography: a noninvasive alternative to cardiac catheterization. Prog Cardiovasc Dis 36:309–342

2. Grossman W, Barry WH (1980) Diastolic pressure-volume relations in the diseased heart. Fed Proc 39:148–155

3. Levine HJ, Gaasch WH (1978) Diastolic compliance of the left ventricle: chamber and muscle stiffness, the volume/mass ratio and clinical implications. Mod Concepts/Cardiovasc Dis 47:99–102

4. Gaasch WH, Levine HJ, Quinones MA et al (1976) Left ventricular compliance:

mechanisms and clinical implications. Am J Cardiol 38:645–653

5. Grossman W, McLaurin LP (1976) Diastolic properties of the left ventricle. Ann Intern Med 84:316–326

6. Mirsky I (1984) Assessment of diastolic function: suggested methods and future considerations. Circulation 69:836–841

7. DeMaria AN, Wisenbaugh T (1987) Identification and treatment of diastolic dysfunction: role of transmitral Doppler recordings. J Am Coll Cardiol 9:1106–1107 8. Labovitz AJ, Pearson AC (1987) Evaluation of left ventricular diastolic function: cli- nical relevance and recent Doppler echocardiographic insights. Am Heart J 114:836–851

9. Kitabatake A, Inoue M, Asao M et al (1982) Transmitral blood flow reflecting dia- stolic behaviour of the left ventricle in health and disease – a study by pulsed Doppler technique. Jpn Circ J 46:92–102

10. Appleton CP, Hatle LK, Popp RL (1988) Relation of transmitral flow velocity pat- terns to left ventricular diastolic function: new insights from a combined hemody- namic and Doppler echocardiographic study. J Am Coll Cardiol 12:426–440 11. Appleton CP, Hatle LK, Popp RL (1988) Demonstration of restrictive ventricular

(6)

physiology by Doppler echocardiography. J Am Coll Cardiol 11:757–768

12. Ohno M, Cheng CP, Little WC (1994) Mechanism of altered filling patterns of left ventricular filling during the development of congestive heart failure. Circulation 89:2241–2250

13. Rihal CS, Nishimura RA, Hatle LK et al (1994) Systolic and diastolic dysfunction in patients with clinical diagnosis of dilated cardiomyopathy: relation to symptoms and prognosis. Circulation 90:2772–2779

14. Xie GY, Berk MR, Smith MD et al (1994) Prognostic value of Doppler transmitral flow patterns in patients with congestive heart failure. J Am Coll Cardiol 24:132–139

15. Pozzoli M, Capomolla S, Opasich C et al (1992) Left ventricular filling pattern and pulmonary wedge pressure are closely related in patients with recent anterior myo- cardial infarction and left ventricular dysfunction. Eur Heart J 13:1067–1073 16. Brunazzi MC, Chirillo F, Pasqualini M et al (1994) Estimation of left ventricular

diastolic pressures from precordial pulsed-Doppler analysis of pulmonary venous and mitral flow. Am Heart J 128:293–300

17. Appleton CP, Galloway JM, Gonzales MS et al (1993) Estimation of left ventricular filling pressures using two-dimensional and Doppler echocardiography in adult patients with cardiac diseases. Additional value of analyzing left atrial size, left atrial ejection fraction, and the difference in duration of pulmonary venous and mitral flow velocity at atrial contraction. J Am Coll Cardiol 22:1972–1982

18. Keren G, Sherez J, Megidish R, Levitt B, Laniado S (1985) Pulmonary venous flow pattern: its relationship to cardiac dynamics. Circulation 71:1105–1112

19. Smiseth OA, Thompson CR, Lohavanichbutr K et al (1999) The pulmonary venous systolic flow pulse: its origin and relationship to left atrial pressure. J Am Coll Cardiol 34:802–809

20. Kopecky SI, Gersh BJ, McGoon MD et al (1987) The natural history of lone atrial fibrillation: a population-based study over three decades. New Engl J Med 317:669–674

21. Kannel WB, Abbott RD, Savane DD et al (1982) Epidemiologic features of chronic atrial fibrillation. N Engl J Med 306:1018–1022

22. Traversi E, Corbelli F, Pozzoli M (2001) Doppler echocardiography reliably predicts pulmonary artery wedge pressure in patients with chronic heart failure even when atrial fibrillation is present. Eur J Heart Fail 3:173–181

23. Pozzoli M, Capomolla S, Pinna G et al (1996) Doppler echocardiography reliably predicts pulmonary artery wedge pressure in patients with chronic heart failure with and without mitral regurgitation. J Am Coll Cardiol 27:883–893

24. Temporelli PL, Scapellato F, Corrà U et al (1999) Estimation of pulmonary wedge pressure by transmitral Doppler in patients with chronic heart failure and atrial fibrillation. Am J Cardiol 83:724–727

25. Nagueh SF, Kopelen HA, Quinones MA (1996) Assessment of left ventricular filling pressure by Doppler in the presence of atrial fibrillation. Circulation 94:2138–2145 26. Brun P, Tribouilloy C, Duval AM et al (1992) Left ventricular flow propagation

during early filling is related to wall relaxation: a color M-mode Doppler analysis. J Am Coll Cardiol 20:420–432

27. Oyama R, Murata K, Tanaka N et al (2004) Is the ratio of transmitral peak E-wave velocity to color flow propagation velocity useful for evaluating the severity of heart failure in atrial fibrillation. Circ J 68:1132–1138

28. Nagueh SF, Middleton KJ, Kopelen HA et al (1997) Doppler tissue imaging: a noninvasive technique for evaluation of left ventricular relaxation and estimation

(7)

of filling pressures. J Am Coll Cardiol 30:1527–1533

29. Ommen S, Nishimura RA, Appleton CP et al (2000) Clinical utility of Doppler echo- cardiography and tissue Doppler imaging in the estimation of left ventricular fil- ling pressures: a comparative simultaneous Doppler-catheterization study.

Circulation 102:1788–1794

30. Dokainish H, Zoghbi WA, Lakkis NM et al (2004) Optimal noninvasive assessment of left ventricular filling pressures: a comparison of tissue Doppler echocardio- graphy and B-type natriuretic peptide in patients with pulmonary artery catheters.

Circulation 109:2432–2439

Riferimenti

Documenti correlati

In Section 3.1 , we perform full spectral fits on our stacked spectra in order to measure their typical stellar velocity dispersions σ∗, while in Section 3.2 we describe the method

Analisi del linguaggio comunicativo di Facebook e studio, messa a punto e risultati di un questionario pubblicato on. Candidato

1) “Norme funzionali e geometriche per la costruzione delle intersezioni stradali”, D.M.. 2) Pratelli A., Appunti del corso di Tecnica del traffico. 3) Tempestini M., Appunti del

Major findings include: erosion of disciplinary boundaries and a corresponding increase in interdisciplinary and multidisciplinary work; a disjunction between

Quattro anticoagulanti orali antagonisti della vitamina K (NOAC), tra cui l'inibitore diretto della trombina dabigatran e gli inibitori diretti del fattore Xa rivaroxaban,

The recurrence of the same principles in all most essential documents of the revolutions that paved the way to modern republicanism proves how fundamental they have been for the

In this paper, we analyzed the existing group modeling strategies and presented criteria for applicable design in real-world scenarios characterized by big data.. As a result of