The use of echocardiography in the critical care setting.

Echocardiography has become an invaluable tool in the management of critically ill patients. Its safety and portability allow for use at the bedside to provide rapid, detailed information regarding the cardiovascular system. Echocardiography can elucidate cardiac structure and mechanical function. Recently, the power of clinical echocardiography has been augmented by the use of Doppler techniques to evaluate cardiovascular hemodynamics. An in-depth understanding of the proper use of echocardiography is a prerequisite for the intensivist.

Comparison of MPEG digital video with super VHS tape for diagnostic echocardiographic readings.

BACKGROUND: Digital recording of echocardiographic studies is on the clinical horizon. However, full digital capture of complete echocardiographic studies in traditional video format is impractical, given current storage capacity and network bandwidth. To overcome these constraints, we evaluated the diagnostic image quality of digital video by using MPEG (Motion Picture Experts Group) compression. METHODS AND RESULTS: Fifty-eight complete, consecutive studies were recorded simultaneously with the use of MPEG-1 and sVHS videotape. Each matched MPEG and sVHS study pair was reviewed by two from a total of six readers, and findings were recorded with the use of a detailed, computerized reporting tool. Intrareader and interreader discrepancies were characterized as major or minor and analyzed in total and for specific subgroups of findings (left and right ventricular parameters, valvular insufficiency, and left ventricular regional wall motion). Intrareader discrepancies were reviewed by a consensus panel for agreement with either MPEG or sVHS findings. There was an exact concordance between MPEG and sVHS readings in 83% of findings. The majority of discrepancies were minor, with major discrepancies in only 2.7% of findings. There was no difference in the rate of consensus panel agreement with MPEG or sVHS for instances of intrareader discrepancy, either in total or for any subgroup of findings. Interreader discrepancy rates were nearly identical for both MPEG and sVHS. CONCLUSIONS: MPEG-1 digital video is equivalent to sVHS videotape for diagnostic echocardiography. MPEG increases the range of practical options for digital echocardiography and offers, for the first time, the advantages of digital recording in a familiar video format.

Accurate noninvasive estimation of left ventricular end-diastolic pressure: comparison with catheterization.

We evaluated the accuracy of a new Doppler-based method using the mitral regurgitant velocity at the time of aortic valve opening for the noninvasive estimation of left ventricular end-diastolic pressure. Sixty unselected patients were studied immediately before routine catheterization. Invasive left ventricular end-diastolic pressure was obtained using a fluid-filled pig-tail catheter. Noninvasive estimation of left ventricular pressure at aortic valve opening was taken as systemic diastolic pressure using an automated cuff. Noninvasive left ventricular end-diastolic pressure was calculated as diastolic blood pressure--4 x (mitral regurgitant velocity at aortic opening)2. Those making noninvasive determinations were blinded to catheterization results. An adequate mitral regurgitant Doppler recording was obtained in 24 patients (40%). In patients with a left ventricular end-diastolic pressure greater than 15 mm Hg the yield was 65%. Left ventricular end-diastolic pressures ranged from 4 mm Hg to 30 mm Hg. Bland and Altman analysis revealed no systematic bias and close agreement was found, with individual discrepancies not exceeding 5 mm Hg.

Effect of left atrial size on recurrence of atrial fibrillation after electrical cardioversion: atrial dimension versus volume.

UNLABELLED: There are conflicting reports on the relationship between left atrial dimension (LAD) determined by echo-cardiography and the incidence of atrial fibrillation (AF) recurrence after electrical cardioversion (EC). We hypothesized that left atrial volume (LAV) by echocardiography might better differentiate patients who will have recurrence of AF after EC. METHODS: Forty-one patients having EC for AF were prospectively studied by echocardiography. LAD was measured by American Society of Echocardiography guidelines as the anterior-posterior dimension in the parasternal view. LAV was measured by Simpson's method using an off-line analysis system and reported as the average of values from the apical four-chamber and two-chamber views. RESULTS: (Data are mean +/- SEM): Patient follow-up was 15 +/- 10 months. No cutoff value of LAV predicted AF recurrence, but all three patients with LAD greater than 65 mm had AF recurrence. Compared with patients maintaining normal sinus rhythm (NSR) (N = 18), the AF group (N = 23) had a lower percentage of antiarrhythmic drug use, especially type IA agents (p < .02). Patients who stayed in NSR tended to have shorter AF duration before EC (16 +/- 15 v 63 +/- 122 weeks, p = .08) but did not differ in age (53 +/- 27 v 58 +/- 23 years), LAD (51.1 +/- 7.7 v 54.2 +/- 9.4 mm) or LAV (85.1 +/- 24.3 v 95.1 +/- 33.3 mL). CONCLUSIONS: (1) LAV by echocardiography does not improve identification of patients at risk for recurrence of AF after EC, (2) patients with LAD up to 65 mm may maintain NSR after EC, (3) LAD greater than 65 mm is associated with AF recurrence, and (4) use of antiarrhythmic drugs and the duration of AF before EC may be better predictors of maintenance of NSR than echocardiographic measures of left atrial parameters.

The effect of esmolol pretreatment on the incidence of regional wall motion abnormalities during electroconvulsive therapy.

Electroconvulsive therapy (ECT) is associated with dramatic increases in arterial blood pressure and heart rate (HR) that may precipitate new left ventricular regional wall motion abnormalities (RWMAs) suggestive of myocardial ischemia. The purpose of this study was to investigate the effect of pretreatment with esmolol on the incidence of RWMAs after ECT. Thirteen patients served as their own controls and, in a random fashion, received a standard succinylcholine/methohexital anesthetic for one of two ECT sessions, and an identical anesthetic with esmolol 1 mg/kg for their other ECT session. Systolic (SBP), diastolic (DBP), mean arterial pressures (MAP) and HR were recorded after drug administration and before ECT and at 1-, 2-, 4-, 5-, 10-, and 15-min intervals after ECT. Echocardiograms were obtained at baseline, after drug administration, 1 min after ECT, and at recovery 15 min later. All patients had significant increases in SBP, DBP, and MAP at 1, 2 and 4 min after ECT versus baseline, whereas HR was significantly faster at all times in the control sessions. HR was significantly slower after anesthetic induction until 2 min after ECT in the esmolol versus the control group (P < 0.05). New RWMAs were seen in only 1 of 26 (4%) ECT sessions, despite the presence of baseline RWMAs in 31% of the patients. We conclude that contrary to previously reported data, new RWMAs after ECT are uncommon. Consequently, this study was unable to demonstrate any beneficial effect of pretreatment with esmolol on the incidence of ECT-induced RWMAs.

Thrombus associated with mitral valve calcification. A possible mechanism for embolic stroke.

BACKGROUND: Several studies have demonstrated an association between mitral annular calcification and stroke; however, the pathophysiological explanation remains speculative. CASE DESCRIPTIONS: We describe two patients with cerebral embolism in whom mitral valve calcification was demonstrated by transthoracic echocardiography. In both patients, transesophageal echocardiography identified a mass that appeared to be thrombus on the calcified portion of the mitral apparatus. There was no evidence of a hypercoagulable state or endocarditis in either case. Repeated transesophageal echocardiography after anticoagulation demonstrated resolution of the masses in both patients. CONCLUSIONS: These cases support the hypothesis that thrombus formation may be a pathophysiological link between ischemic cerebral events and mitral annular calcification in some patients.

Oxygen delivery and uptake relationships in patients with aortic stenosis.

Previous studies have reported finding supply-dependent O2 uptake (VO2) in patients with the adult respiratory distress syndrome, sepsis, chronic obstructive lung disease, sleep apnea, and other cardiopulmonary diseases. A common element among these diverse conditions is the potential to reduce systemic O2 delivery (QO2 = cardiac output.arterial O2 content). The aim of the present study was to determine whether patients with aortic stenosis also exhibit increases in VO2 when O2 delivery is increased after valvuloplasty. Fifty-six patients were studied while breathing room air in the supine position. Expired gases for determination of O2 uptake (VO2 [measured]), cardiac output (thermodilution), arterial and mixed venous blood gases, and hemodynamic measurements were obtained immediately before and within 30 min after aortic valvuloplasty. After valvuloplasty, VO2 (measured) increased from 3.03 +/- 0.51 to 3.24 +/- 0.62 ml/min/kg (p < 0.0001). However, O2 extraction ratio did not change from baseline levels (32.16 +/- 10.1%) after valvuloplasty (32.21 +/- 8.25%, p = not significant). These results could have occurred only if O2 delivery had also increased. Accordingly, Fick-derived Q and corresponding QO2 (Fick) both increased significantly, suggesting the presence of O2 supply-dependent VO2. However, neither Q (thermodilution) nor QO2 (thermodilution) changed significantly, and regression of VO2 (measured) against QO2 (thermodilution) failed to detect a relationship. We conclude that patients with aortic stenosis exhibit increases in O2 delivery and uptake after valvuloplasty, although this may or may not reflect covert tissue hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)