Bruce W. Usher

Mitral valve replacement with and without chordal preservation in patients with chronic mitral regurgitation. Mechanisms for differences in postoperative ejection performance.

BackgroundStandard mitral valve replacement (MVR) in patients with chronic mitral regurgitation consistently results in a decrease in postoperative left ventricular (LV) ejection performance. This fall in ejection performance has been attributed, at least in part, to unfavorable loading conditions imposed by the elimination of the lowimpedance pathway for LV emptying into the left atrium. In contrast to standard MVR in which the chordae tendineae are severed, however, MVR with chordal preservation (MVR-CP) does not usually decrease LV ejection performance despite similar removal of the low-impedance pathway. The purpose of the present study was to define the mechanisms responsible for this discordance in postoperative ejection performance between MVR with and without chordal preservation. Methods and ResultsEchocardiography and sphygmomanometer blood pressures were obtained in 15 patients with pure chronic mitral regurgitation before and 7-10 days after mitral valve surgery. These measurements were used to calculate ventricular volume, wall stress, and ejection fraction. Seven patients underwent MVR with chordal transection (MVR-CT), and eight patients underwent MVR-CP. MVR-CT resulted in no postoperative change in LV end-diastolic volume, a significant increase in LV end-systolic volume, a significant increase in end-systolic stress, from 89 ± 9 to 111 ± 12 g/cm2 (p < 0.05), and a significant decrease in ejection fraction, from 0.60 ± 0.02 to 36 ± 0.02 (p < 0.05). In contrast, patients who underwent MVR-CP had a significant decrease in LV end-diastolic and end-systolic volumes. End-systolic wall stress actually fell from 95 ± 6 to 66 ± 6 g/cm2 (p < 0.05), and ejection fraction was unchanged (0.63 ± 0.01 before and 0.61 ± 0.02 after mitral valve surgery) instead of reduced. ConclusionsMVR-CT resulted in a decrease in ejection performance caused in part by an increase in end-systolic stress, which in turn increased end-systolic volume. Conversely, MVR-CP resulted in a smaller LV size, allowing a reduced end-systolic stress and preservation of ejection performance despite closure of the low-impedance left atrial ejection pathway.

Predictors of outcome for aortic valve replacement in patients with aortic regurgitation and left ventricular dysfunction: A change in the measuring stick

Although left ventricular function is generally regarded as a key determinant of prognosis in aortic regurgitation, predictors of outcome of aortic valve replacement based on this factor have recently been questioned. This study was performed to examine the role of indexes of left ventricular function in predicting the outcome of surgery in patients with aortic regurgitation and left ventricular dysfunction. Fourteen patients with aortic regurgitation with a preoperative ejection fraction of less than 0.55 (average 0.45 +/- 0.02) who underwent aortic valve replacement were studied. The patients had 82 (58%) of a possible 140 predictors of negative outcome preoperatively, but 12 of the 14 patients had a decrease in symptoms and an increase in ejection fraction into the normal range after operation (average postoperative ejection fraction 0.59 +/- 0.04). Although improvement occurred despite the presence of many negative predictors of outcome, there was a significant correlation between postoperative ejection fraction and eight of the tested preoperative predictors. Preoperative end-systolic dimension correlated best (r = -0.91) with postoperative ejection fraction. An end-systolic dimension of 60 mm correlated with a postoperative ejection fraction of 0.55. The results indicate that preoperative ventricular function is still an important determinant of outcome of aortic valve replacement for aortic regurgitation. However, current medical and surgical techniques permit a better prognosis in the presence of reduced ventricular function than was previously considered possible.

Incidence of acute myocardial infarction in patients with exercise-induced silent myocardial ischemia

Fifty-five patients with angiographically proved coronary artery disease (CAD) underwent Bruce protocol exercise stress testing with thallium-201 imaging. Twenty-seven patients (group I) showed myocardial hypoperfusion without angina pectoris during stress, which normalized at rest, and 28 patients (group II) had a similar pattern of reversible myocardial hypoperfusion but also had angina during stress. Patients were followed for at least 30 months. Six patients in group I had an acute myocardial infarction (AMI), 3 of whom died, and only 1 patient in group II had an AMI (p = 0.05), and did not die. Silent myocardial ischemia uncovered during exercise stress thallium testing may predispose to subsequent AMI. The presence of silent myocardial ischemia identified in this manner is of prognostic value, independent of angiographic variables such as extent of CAD and left ventricular ejection fraction.

Validity of electrocardiographic estimates of left ventricular hypertrophy and mass in African Americans (The Charleston Heart Study)

The Cornell voltage criteria and the Novacode computer model for estimating left ventricular mass were compared to echocardiographic left ventricular mass in African Americans from the Charleston Heart Study. The diagnostic accuracy of these electrocardiographic models compared with the echocardiogram is similar to the previous study in whites.

Doppler Color Flow Imaging in Detection and Mapping of Left Coronary Artery Fistula to Right Ventricle and Atrium

Two patients who had left coronary artery fistulas that drained into the right ventricle (case 1) and right atrium (case 2) were studied with combined two-dimensional echocardiography and Doppler color flow imaging. The origin of the fistulas from the left coronary artery, their course, and drainage sites were readily identified. These cases illustrate the enhanced identification of left coronary artery fistulas and the drainage sites with the addition of Doppler color flow imaging to two-dimensional echocardiography.

Cardiovascular status of panic disorder patients with and without prominent cardiac symptoms

The extent of the cardiovascular evaluation of panic disorder patients with cardiac symptoms remains a dilemma for the clinician. The authors conducted a pilot study to assess the cardiac status of 20 panic disorder patients, 10 of whom had prominent cardiac symptoms and 10 of whom did not. No differences in the cardiac abnormalities were found between the groups. These findings suggest that panic disorder patients with cardiac symptoms are not more likely to have cardiac disease than those without prominent cardiac symptoms. The practical implications of these findings are discussed.

Differences in Right Ventricular Functional Changes during Treatment between Systemic Sclerosis-Associated Pulmonary Arterial Hypertension and Idiopathic Pulmonary Arterial Hypertension.

Rationale: Patients with systemic sclerosis‐associated pulmonary arterial hypertension (SSc‐PAH) continue to have an unacceptably high mortality rate despite the progress achieved with pulmonary arterial vasodilator therapies. Objectives: We sought to determine whether SSc‐PAH is a clinically distinct pulmonary vascular disease phenotype when compared with idiopathic pulmonary arterial hypertension (IPAH) on the basis of progression of echocardiographic right ventricular (RV) dysfunction. Methods: Retrospective analysis of echocardiographic data in 13 patients with SSc‐PAH and 11 patients with IPAH was used to delineate the progression of RV dysfunction during single or combination pulmonary arterial vasodilator therapy. All patients had right heart catheterization‐confirmed pulmonary arterial hypertension as well as complete baseline (at the time of diagnosis) and follow‐up (most recent) echocardiograms. We excluded patients with significant scleroderma‐associated interstitial lung disease. Adjusting for time of follow‐up and disease duration, we performed mixed model regression analyses comparing the changes between the two groups for different echocardiographic variables: tricuspid annular plane systolic excursion, tricuspid regurgitation jet velocity, right atrial area, and RV diameter. Results: The mean ages for the SSc‐PAH and IPAH groups were 60.8 and 48.2 years, respectively. The mean follow‐up periods for the two groups were 3.8 and 1.95 years, respectively. Tricuspid annular plane systolic excursion did not improve in patients with SSc‐PAH, whereas it increased in the patients with IPAH (−0.38 mm, P = 0.87; vs. +5.6 mm, P = 0.02). The other echocardiographic variables showed a trend toward worsening in the SSc‐PAH group and improvement in the IPAH group. Conclusions: Our results indicate that, in patients with SSc‐PAH, echocardiographic RV function does not improve over time compared with that of patients with IPAH, despite institution of pulmonary artery vasodilator therapies.

Role of Transesophageal Echocardiography Among Patients With Atrial Fibrillation Undergoing Electrophysiology Testing

External or internal shocks administered to terminate ventricular arrhythmias as a part of electrophysiology or implantable cardioverter-defibrillator testing, can inadvertently cardiovert atrial fibrillation (AF). Moreover, anticoagulation therapy is often withheld in these patients in anticipation of an invasive procedure. The risk of embolic events during these procedures has not been well described. Accordingly, the present study was a prospective evaluation of the incidence of left atrial (LA) thrombus and AF cardioversion among patients undergoing ventricular arrhythmia assessment. Transesophageal echocardiography was routinely performed on 44 consecutive patients in AF with subtherapeutic anticoagulation undergoing electrophysiology or implantable cardioverter-defibrillator testing. Arrhythmia induction was not performed when LA thrombus was present. The incidence and clinical predictors of thrombus, the inadvertent cardioversion of AF, and adverse events related to the procedure were assessed during the subsequent 4 to 6 weeks. Left atrial thrombus was observed in 12 patients (27%). Sinus rhythm was restored in 29 patients (91%), at least transiently, who underwent testing with a shock delivered. No adverse neurologic or hemorrhagic complications were observed. Univariate analysis identified no predictors of LA thrombus or cardioversion to sinus rhythm. In conclusion, LA thrombus and cardioversion to sinus rhythm are common among patients with AF undergoing an evaluation of ventricular arrhythmias. Transesophageal echocardiography performed before the procedure in patients with subtherapeutic anticoagulation is warranted to minimize embolic complications. This strategy appears to be a safe method to guide diagnostic testing in this patient population.

Noninvasive diagnosis of a false left ventricular aneurysm

Abstract A case of a surgically corrected false ventricular aneurysm is presented. The roles of computerized tomography as well as other noninvasive modalities are reviewed.