G. Van Camp

Mitral regurgitation in patients with aortic stenosis undergoing valve replacement

Mitral regurgitation is a frequent finding in patients with aortic stenosis scheduled for aortic valve replacement. Detection of mitral regurgitation in such patients has important implications, as it can independently affect functional status and prognosis. When mitral regurgitation is moderate to severe, a decision to operate on both valves should only be made following a careful clinical and echocardiographic assessment. Indeed, double-valve surgery increases perioperative and postoperative risks, and mitral regurgitation may improve spontaneously after isolated aortic valve replacement. Better understanding of the determinants of these changes appears particularly crucial in the light of recent advances in percutaneous aortic valve replacement.

Impact of prosthesis–patient mismatch on mitral regurgitation after aortic valve replacement

Background Mitral regurgitation is frequently observed in patients undergoing aortic valve replacement (AVR) for aortic stenosis and often improves postoperatively, mainly due to left ventricular remodelling and changes in loading conditions. Aortic prosthesis–patient mismatch (PPM) is associated with poor outcome and lesser left ventricular remodelling. This study tested the hypothesis that aortic PPM affects mitral regurgitation. Methods and results Echocardiography was performed preoperatively and before discharge in 42 patients with aortic stenosis undergoing isolated AVR and presenting mitral regurgitation with an effective regurgitant orifice (ERO) of 10 mm2 or greater, as assessed by the proximal isovelocity surface area method. Postoperatively, mitral ERO and the regurgitant volume decreased from 16±5 mm2 to 12±6 mm2 (p<0.001) and from 28±8 ml to 16±9 ml (p<0.0001), respectively. PPM (indexed effective prosthetic valve area (EOAi) ≤0.85 cm2/m2), present in 23 patients (55%), was associated with a smaller decrease in regurgitant volume (p=0.0025) and ERO (p=0.02). A functional aetiology of mitral regurgitation was associated with a larger improvement in mitral regurgitation. In the whole cohort, EOAi correlated with the changes in mitral regurgitation severity (ERO r=0.44, p=0.01; regurgitant volume r=0.47, p=0.003). However, these relationships were no longer significant in the subset of patients with functional mitral regurgitation in whom mitral regurgitation changes were mainly related to postoperative changes in mitral valve deformation. Conclusions The presence of PPM after AVR attenuates postoperative mitral regurgitation changes, mainly in patients with organic mitral regurgitation.

Influence of Heart Rate Reduction on Doppler Myocardial Imaging Parameters in a Small Animal Model

In small animals studies, sick animals often have a significant reduction in heart rate while under anesthesia. The influence of heart rate reduction on Doppler myocardial imaging (DMI) parameters is not known. The aim of the present study was to assess the effect of heart rate reduction on DMI parameters in a small animal model. Twenty-four rats underwent transthoracic echocardiography at baseline and during the administration of ivabradine IV. In all rats, left ventricular (LV) systolic velocity, strain and strain rate were measured in the anteroseptal and inferolateral wall segments from short axis views. In 12 rats (group A), M-mode analysis was also performed for assessment of global LV function. In the other 12 rats (groups B), contractility was quantified invasively using the end-systolic pressure-volume relation (ESPVR) and the preload recruitable stroke work (PRSW). During ivabradine, administration heart rate decreased by 18% in group A (p < 0.001) and 36% in group B (p < 0.001). There was a slight increase in LVEDD and LVESD, with no change in cardiac output or LV ejection fraction. During ivabradine administration, DMI parameters did not change significantly in any group. No significant correlation between DMI parameters and heart rate (r(2) = 0.05) or ejection time (r(2) = 0.14) could be found. The absence of changes in contractility was confirmed by the absence of change in PRSW and end-systolic elastance (Ees). In conclusion, moderate heart rate reduction did not influence DMI measurements in this specific rat model. Therefore, in the interpretation of DMI data when performing small animal studies, moderate heart rate reduction does not need to be taken into account.

Contrast harmonic imaging improves the evaluation of left ventricular function in ventilated patients: comparison with transesophageal echocardiography

AIMS The study examined the value of contrast echocardiography (CE) in the assessment of left ventricular (LV) wall motion in ventilated patients in comparison with transesophageal (TOE) and standard fundamental transthoracic imaging (SE). METHODS Transthoracic echocardiograms were done in 40 ventilated patients. Wall motion was evaluated using the recommendations of the American Society of Echocardiography on SE, CE and TOE. A visualization score was assigned on a scale of 2-0 for each of 16 segments. The segment was assigned a value of 2 if the segment was seen in both systole and diastole, 1 if seen only in systole or diastole, and 0 if not seen at all. A confidence score was also given for each segment with each technique (unable to evaluate; not sure; sure). The ejection fraction (EF) was estimated visually for each technique, and a confidence score was also applied to the EF. RESULTS Visualization score 0 was present in 6.2 segments/patient on SE, 1.2 on CE (P<0.0001) and 1.1 on TOE (P<0.0001). An average of 6.5 segments were read with surety on SE, 11.5 on CE (P<0.0001) and 12.3 on TOE ( P<0.0001 ). There was no significant difference for CE vs TOE. EF was uninterpretable in 32% on SE, 0% on CE (P<0.001 and 0% on TOE (P<0.001). The EF was read with surety in 53% of patients on SE, 88% on CE (P < 0.0001) and 93% with TOE (P<0.0001) with no difference for CE vs TOE. Thus, wall motion was seen with more confidence on CE and TOE. CONCLUSIONS In the ventilated patients with suboptimal transthoracic echocardiograms for the evaluation of the LV function, CE provides image quality of regional and global LV function similar to that achieved with TOE echocardiography.

Ruptured aortic dissection into the left atrium which presented as congestive heart failure and was diagnosed by transoesophageal echocardiography

A 72 year old man was admitted with severe dyspnoea. Ten days before he had had intense thoracic pain with loss of consciousness that was followed by increased dyspnoea. A continuous murmur was heard in the precordial and the left infrascapular regions. Lung auscultation showed stasis over the lower half of both lungs. Transthoracic echocardiography showed a bicuspid aortic valve and a dissection of the proximal aorta, which was considerably enlarged. Transoesophageal echocardiography confirmed dissection of the proximal aorta and showed a communication from the false lumen of the aortic dissection to the left atrium; and colour flow Doppler showed a continuous shunt to the left atrium. After transoesophageal echocardiography the patient had emergency surgical repair, which was successful. He had no complications in the post-operative period.

Early diastolic mitral insufficiency due to asynchrony of left ventricular contraction

A 75-year-old woman with a history of congestive heart failure and DDD pacemaker implantation, was found to have early diastolic mitral insufficiency on Doppler echocardiography. This is the first case description of early diastolic mitral insufficiency and mechanisms contributing to this phenomenon are discussed.