To the Editor:
In Table 3 of their recent review, Haddad et al.1 present normal values for the functional variables of the right ventricle. In the legend, the authors state that “almost all normal values had been established in nonventilated patients.” Although they stress the load dependency of the presented parameters, they offer no recommendation as to the application of these values in anesthetized and ventilated patients undergoing cardiac surgery, as they do not stress the age dependency of the tissue Doppler imaging parameters.2,3
In a prospective and randomized study, our group investigated right ventricular (RV) function in patients undergoing elective on-pump and off-pump coronary bypass surgery.4 The patients were clinically stable and had neither pulmonary hypertension nor a history of myocardial infarction involving the right ventricle. The day before surgery, they underwent transthoracic echocardiography that revealed normal RV global and regional function and no more than mild tricuspid regurgitation. The same patients were studied the next day using transesophageal echocardiography (TEE) after induction of balanced anesthesia, muscle relaxation, and intermittent positive pressure ventilation. TEE studies were performed during hemodynamic stability and normoventilation before opening the sternum. The transthoracic echocardiography and TEE values of three parameters obtained by spectral pulsed wave Doppler echocardiography in end expiration are reported in Table 1. The inferior tricuspid annular plane maximal systolic and diastolic velocities measured in the transgastric RV inflow view during general anesthesia and intermittent positive pressure ventilation4 were significantly less than those assessed during the preoperative transthoracic study in the awake and spontaneously breathing patients5 (submitted data). The measured values were also markedly less than those presented by Haddad et al. as normal values in Table 3 of their review. The lateral tricuspid annular plane maximal early diastolic velocities (Et) reported in our awake patients5 were slightly less than those reported as normal values,1–3 but quite comparable with the values reported by Alam6 in patients with coronary artery disease before bypass surgery, suggesting a possible preoperative diastolic dysfunction due to the coronary disease.
David et al.7 also measured inferior tricuspid annular plane maximal systolic velocity in anesthetized coronary patients before opening the sternum and reported values of 5.2 ± 1.2 cm/s, which are similar to those in our patients during anesthesia and mechanical ventilation.
These data show that general anesthesia, muscle relaxation, and mechanical ventilation have marked effects on tissue Doppler parameters of RV systolic and diastolic function. Therefore, applying reference values obtained from awake, spontaneously breathing subjects to anesthetized and mechanically ventilated patients is associated with the risk of falsely diagnosing impaired systolic or diastolic function in patients with preserved cardiac function. There is a clear need for studies to establish normal TEE values in anesthetized and mechanically ventilated patients, even if we are aware of the difficulty separating the effects of anesthesia from those of the disease, on the different Doppler parameters.
Isabelle Michaux, MD
Department of Intensive Care Medicine
Mont-Godinne University Hospital
Université Catholique de Louvain
Miodrag Filipovic, MD
Manfred Seeberger, MD
Karl Skarvan, MD
Department of Anesthesia
University Hospital Basel
University of Basel
1. Haddad F, Couture P, Tousignant C, Denault AY. The right ventricle in cardiac surgery, a perioperative perspective: I. Anatomy, physiology, and assessment. Anesth Analg 2009;108:407–21
2. Alam M, Wardell J, Andersson E, Samad BA, Nordlander R. Characteristics of mitral and tricuspid annular velocities determined by pulsed wave Doppler tissue imaging in healthy subjects. J Am Soc Echocardiogr 1999;12:618–28
3. Lindqvist P, Waldenstrom A, Henein M, Morner S, Kazzam E. Regional and global right ventricular function in healthy individuals aged 20-90 years: a pulsed Doppler tissue imaging study: Umea General Population Heart Study. Echocardiography 2005;22:305–14
4. Michaux I, Filipovic M, Skarvan K, Schneiter S, Schumann R, Zerkowski HR, Bernet F, Seeberger MD. Effects of on-pump versus off-pump coronary artery bypass graft surgery on right ventricular function. J Thorac Cardiovasc Surg 2006;131:1281–8
5. Michaux I, Filipovic M, Skarvan K, Bollinger D, Seeberger MD. Right ventricular function after on-pump versus off-pump coronary bypass graft surgery. A TDI study. Eur J Anaesthesiol 2006;23(suppl 38):5
6. Alam M, Hedman A, Nordlander R, Samad B. Right ventricular function before and after an uncomplicated coronary artery bypass graft as assessed by pulsed wave Doppler tissue imaging of the tricuspid annulus. Am Heart J 2003;146:520–6
7. David JS, Tousignant CP, Bowry R. Tricuspid annular velocity in patients undergoing cardiac operation using transesophageal echocardiography. J Am Soc Echocardiogr 2006;19:329–34