Kwan-Leung Chan

CONTINUOUS WAVE DOPPLER DETERMINATION OF RIGHT VENTRICULAR PRESSURE: A SIMULTANEOUS DOPPLER-CATHETERIZATION STUDY IN 127 PATIENTS

Simultaneous continuous wave Doppler echocardiography and right-sided cardiac pressure measurements were performed during cardiac catheterization in 127 patients. Tricuspid regurgitation was detected by the Doppler method in 117 patients and was of adequate quality to analyze in 111 patients. Maximal systolic pressure gradient between the right ventricle and right atrium was 11 to 136 mm Hg (mean 53 +/- 29) and simultaneously measured Doppler gradient was 9 to 127 mm Hg (mean 49 +/- 26); for these two measurements, r = 0.96 and SEE = 7 mm Hg. Right ventricular systolic pressure was estimated by three methods from the Doppler gradient. These were 1) Doppler gradient + mean jugular venous pressure; 2) using a regression equation derived from the first 63 patients (Group 1); and 3) Doppler gradient + 10. These methods were tested on the remaining 48 patients with Doppler-analyzable tricuspid regurgitation (Group 2). The correlation between Doppler-estimated and catheter-measured right ventricular systolic pressure was similar using all three methods; however, the regression equation produced a significantly better estimate (p less than 0.05). Use of continuous wave Doppler blood flow velocity of tricuspid regurgitation permitted determination of the systolic pressure gradient across the tricuspid valve and the right ventricular systolic pressure. This noninvasive technique yielded information comparable with that obtained at catheterization. Approximately 80% of patients with increased and 57% with normal right ventricular pressure had analyzable Doppler tricuspid regurgitant velocities that could be used to accurately predict right ventricular systolic pressure.

Effect of Lipid Lowering With Rosuvastatin on Progression of Aortic Stenosis Results of the Aortic Stenosis Progression Observation: Measuring Effects of Rosuvastatin (ASTRONOMER) Trial

Background— Aortic stenosis (AS) is an active process with similarities to atherosclerosis. The objective of this study was to assess the effect of cholesterol lowering with rosuvastatin on the progression of AS. Methods and Results— This was a randomized, double-blind, placebo-controlled trial in asymptomatic patients with mild to moderate AS and no clinical indications for cholesterol lowering. The patients were randomized to receive either placebo or rosuvastatin 40 mg daily. A total of 269 patients were randomized: 134 patients to rosuvastatin 40 mg daily and 135 patients to placebo. Annual echocardiograms were performed to assess AS progression, which was the primary outcome; the median follow-up was 3.5 years. The peak AS gradient increased in patients receiving rosuvastatin from a baseline of 40.8±11.1 to 57.8±22.7 mm Hg at the end of follow-up and in patients with placebo from 41.6±10.9 mm Hg at baseline to 54.8±19.8 mm Hg at the end of follow-up. The annualized increase in the peak AS gradient was 6.3±6.9 mm Hg in the rosuvastatin group and 6.1±8.2 mm Hg in the placebo group (P=0.83). Treatment with rosuvastatin was not associated with a reduction in AS progression in any of the predefined subgroups. Conclusion— Cholesterol lowering with rosuvastatin 40 mg did not reduce the progression of AS in patients with mild to moderate AS; thus, statins should not be used for the sole purpose of reducing the progression of AS. Clinical Trial Registration Information— URL: http://www.controlled-trials.com/. Clinical trial registration number: ISRCTN 32424163.

EAE/ASE Recommendations for the Use of Echocardiography in New Transcatheter Interventions for Valvular Heart Disease.

The introduction of devices for transcatheter aortic valve implantation, mitral repair, and closure of prosthetic paravalvular leaks has led to a greatly expanded armamentarium of catheter-based approaches to patients with regurgitant as well as stenotic valvular disease. Echocardiography plays an essential role in identifying patients suitable for these interventions and in providing intra-procedural monitoring. Moreover, echocardiography is the primary modality for post-procedure follow-up. The echocardiographic assessment of patients undergoing trans-catheter interventions places demands on echocardiographers that differ from those of the routine evaluation of patients with native or prosthetic valvular disease. Consequently, the European Association of Echocardiography in partnership with the American Society of Echocardiography has developed the recommendations for the use of echocardiography in new transcatheter interventions for valvular heart disease. It is intended that this document will serve as a reference for echocardiographers participating in any or all stages of new transcatheter treatments for patients with valvular heart disease.

A Prospective Study to Assess the Frequency of Familial Clustering of Congenital Bicuspid Aortic Valve

OBJECTIVES This study sought to determine the rate of familial occurrence of congenital bicuspid aortic valve (BAV) by using echocardiography to screen family members. BACKGROUND Congenital BAV is a common anomaly that carries with it a significant risk of potential long-term cardiac complications. Despite several reports of the familial occurrence of BAV, the condition is not generally considered to be inherited. METHODS Thirty consecutive patients with echocardiographically documented congenital BAV were interviewed to construct three-generation family pedigrees. All first-degree relatives were contacted to undergo echocardiography to specifically determine aortic valve morphology. RESULTS Of the 210 first-degree relatives, 190 (90.5%) agreed to undergo echocardiography. Four members had technically difficult studies. Of the remaining 186 subjects, 17 (9.1%) were identified as having BAV; 11 (36.7%) of the 30 families had at least one additional member with the condition. The male/female ratio of affected members in the 11 families was 1. In one family, two instances of male-to-male transmission were observed. The distribution of BAV in the majority of multiplex families is compatible with autosomal dominant inheritance with reduced penetrance. CONCLUSIONS We demonstrated a high incidence of familial clustering in congenital BAV. We believe that the high rate of occurrence of the condition in immediate relatives justifies echocardiographic screening of first-degree relatives to anticipate and prevent future complications associated with this common cardiac malformation.

Angiotensin Receptor Blockade and Exercise Capacity in Adults With Systemic Right Ventricles A Multicenter, Randomized, Placebo-Controlled Clinical Trial

Background— Pharmacological blockade of the renin-angiotensin system improves exercise tolerance in patients with left ventricular dysfunction, yet its impact on patients with systemic right ventricles (RVs) remains unknown. Methods and Results— A multicenter, randomized, double-blind, placebo-controlled, crossover clinical trial was performed to assess the effects of losartan on exercise capacity and neurohormonal levels in patients with systemic RVs. Of 29 patients studied (age, 30.3±10.9 years), 21 had transposition of the great arteries with a Mustard baffle, and 8 had congenitally corrected transposition of the great arteries. Baseline values were as follows: &OV0312;o2max, 29.8±5.6 mL · kg−1 · min−1 (73.5±12.9% predicted value); RV ejection fraction, 41.6±9.3%; N-terminal pro brain natriuretic peptide (NT-proBNP), 257.7±243.4 pg/mL (normal <125 pg/mL); and angiotensin II, 5.7±4.9 pg/mL (normal <5.0 pg/mL). Comparing losartan to placebo showed no differences in &OV0312;o2max (29.9±5.4 versus 29.4±6.2 mL · kg−1 · min−1; P=0.43), exercise duration (632.3±123.0 versus 629.9±140.7 seconds; P=0.76), and NT-proBNP levels (201.2±267.8 versus 229.7±291.5 pg/mL; P=0.10), despite a trend toward increased angiotensin II levels (15.2±13.8 versus 8.8±12.5 pg/mL; P=0.08). Conclusions— In adults with systemic RVs, losartan did not improve exercise capacity or reduce NT-proBNP levels. Minimal baseline activation of the renin-angiotensin system may explain this lack of benefit and imply an alternative pathophysiological mechanism for the progressive ventricular dysfunction and impaired exercise capacity observed in such patients.

Aortic aneurysm in patients with functionally normal or minimally stenotic bicuspid aortic valve.

Bicuspid aortic valve (BAV) is the most common form of congenital valvular disease, with a prevalence of approximately 1 to 2% in the general population.1 Aortic coarctation is often associated with BAV.1 A recent editorial by Lindsay2 has drawn attention once again to the concept that BAV and aortic coarctation may be manifestations of a single developmental anomaly—namely, aortic medial fragility. This idea was initially proposed by Abbot3 in 1928, revived by McKusick4 in 1972, and supported by circumstantial evidence referred to by Lindsay in his editorial. To prove that aortic medial fragility underlies BAV and aortic coarctation, one must demonstrate the presence of a pathologic or clinical correlate of aortic medial fragility in patients with the index conditions. The proposed pathologic correlate, cystic medial necrosis, is nonspecific. The clinical correlates of aortic medial fragility include aortic dilatation (aneurysm) or dissection. Although the data cited by Lindsay are suggestive of an increased prevalence of aortic dilatation/ dissection with BAV and coarctation, they could be expressions of the hemodynamic alterations accompanying the index conditions rather than manifestations of aortic medial fragility. To eliminate the confounding influence of hemodynamic disturbances, we studied the prevalence of aortic root dilatation (aneurysm) in patients with a functionally normal or minimally stenotic BAV. This study was to determine whether the aortic root at the sinus level is significantly dilated in patients with a functionally normal or minimally stenotic BAV, which we define as a resting mean aortic valve gradient <25 mm Hg, the absence of anything more than trivial aortic regurgitation and no coarctation as determined by Doppler echocardiography.

Implication of negative results on a monoplane transesophageal echocardiographic study in patients with suspected infective endocarditis

OBJECTIVES This study was conducted to determine the implications of negative findings on a transesophageal echocardiographic study in which neither a vegetation nor an abscess is identified in patients with clinically suspected infective endocarditis. BACKGROUND Echocardiography is the procedure of choice for evaluating suspected infective endocarditis in patients. Transesophageal echocardiography has been shown to be superior to transthoracic imaging. Although the importance of positive results or a diagnostic study is known, the significance of negative findings on a transesophageal study is not clear. METHODS All transesophageal echocardiographic studies performed over a 2-year period for suspected infective endocarditis were reviewed and the clinical course of patients with an initially negative study result was assessed to determine their final diagnosis. RESULTS Of the 105 patients identified, 65 had a negative transesophageal study result. In the majority of this group (56 of 65), an alternate diagnosis was made or there was no infective endocarditis on follow-up examination, or both. Of the remaining nine patients, four were treated for endocarditis without a definite diagnosis and five had infective endocarditis proved by either repeat transesophageal study (n = 3), pathologic findings (n = 1) or a diagnostic clinical course (n = 1). Gram-positive bacteremia and the presence of a prosthetic valve in the aortic position tended to be more common in the latter group. CONCLUSIONS A negative transesophageal study result reduces the likelihood that endocarditis is present. Repeat examination, however, should be considered in high risk patients, such as those with prosthetic valves or unexplained bacteremia, to avoid a missed diagnosis.

Role of transesophageal echocardiography in the diagnosis and management of prosthetic valve thrombosis

Thrombosis is a serious complication of heart valve replacement. Diagnosis is often difficult with previously reported techniques, including precordial two-dimensional echocardiography, suffering from low sensitivity and specificity. Management is similarly difficult, with a 40% to 50% reported mortality rate in early surgical series. Three cases are presented in which thrombosis of a left-sided prosthetic valve (one aortic, three mitral) was diagnosed by means of transesophageal echocardiography. All three patients were treated with streptokinase and had clinical and echocardiographic resolution. In one patient, who had recurrent thrombosis and received a second course of streptokinase, the course was complicated by a massive embolic stroke and death. Another patient with a recurrence underwent successful valve replacement. Transesophageal echocardiography is ideal for the diagnosis and follow-up of patients with prosthetic valve thrombosis. Although effective, thrombolysis in this setting is associated with a high risk of thromboembolic phenomena and significant risk of death. Thrombolytic therapy may be considered in highly selected patients who have an unacceptable risk for reoperation.

Metabolic syndrome is associated with more pronounced impairment of left ventricle geometry and function in patients with calcific aortic stenosis: a substudy of the ASTRONOMER (Aortic Stenosis Progression Observation Measuring Effects of Rosuvastatin).

OBJECTIVES The aim of this study was to examine the relationship between metabolic syndrome (MetS) and left ventricular (LV) geometry and function in patients with asymptomatic aortic stenosis (AS). BACKGROUND Recent experimental studies reveal that, among animals with sustained pressure overload, those with insulin resistance induced by a high-carbohydrate/high-fat diet have more severe LV hypertrophy and dysfunction compared to animals fed with standard diet. METHODS Among the 272 patients who were recruited in the ASTRONOMER (Aortic Stenosis Progression Observation Measuring Effects of Rosuvastatin) study, none had hypercholesterolemia, diabetes mellitus, or coronary artery disease (exclusion criteria) at baseline. However, 33% had systemic hypertension and 27% had MetS as identified by the National Cholesterol Education Program, Adult Treatment Panel III, clinical criteria. RESULTS Patients with MetS had higher LV mass index (53 +/- 14 g/m(2.7) vs. 47 +/- 15 g/m(2.7); p = 0.002), relative wall thickness ratio (0.47 +/- 0.09 vs. 0.42 +/- 0.09; p = 0.001), and prevalence of LV concentric hypertrophy (42% vs. 23%) and lower peak early diastolic (8.2 +/- 2.4 cm/s vs. 9.6 +/- 3.1 cm/s, p = 0.001) and peak systolic (7.9 +/- 1.7 cm/s vs. 8.7 +/- 2.2 cm/s, p = 0.009) mitral annular myocardial velocities compared to patients without MetS. After adjustment for age, sex, low-density lipoprotein cholesterol, hypertension, and valvuloarterial impedance (i.e., global LV hemodynamic load), MetS was independently associated with higher relative wall thickness ratio (p = 0.01), higher prevalence of concentric hypertrophy (p = 0.03), and reduced diastolic (p = 0.01) and systolic (p = 0.03) myocardial velocities. CONCLUSIONS Notwithstanding AS severity and increase in hemodynamic load, MetS is independently associated with more pronounced LV concentric hypertrophy and worse myocardial function in patients with AS, which may, in turn, predispose them to the occurrence of adverse events. (Effects of Rosuvastatin on Aortic Stenosis Progression [ASTRONOMER]; NCT00800800).

Is aortic stenosis a preventable disease

Aortic stenosis (AS) is the most common valvular disease requiring valve replacement. Its prevalence increases with age. When the severity of AS is only mild to moderate, it is well tolerated. When it becomes severe, AS confers significant morbidity and mortality. Adverse events can be avoided if it is possible to prevent or retard the progression from mild or moderate AS to severe AS. Progression of AS parallels the progression of sclerotic changes involving the aortic valve, which share histological and immunochemical similarities with the process of atherosclerosis. Far from being just a degenerative process, the development of AS is a complex and highly regulated process with a number of modifiable factors. One of the key factors appears to be lipoproteins, which are intimately involved in several pathways crucial to the development of AS. The importance of lipoproteins is further supported by epidemiological and clinical studies showing a strong association between lipoproteins and AS. The time has come to initiate prospective studies to assess the effect of cholesterol lowering on the progression of AS.