SUMMARY Left atrial function was evaluated in patients with and without remote myocardial infarction. The simultaneous left atrial pressure recording and left atrial and left ventricular cineangiograms were obtained with a catheter-tip micromanometer. The pressure-volume curve of the left atrium was composed of an A-loop and a V-loop. The ratio of active atrial emptying to left ventricular stroke volume in patients with myocardial infarction was significantly larger than that in normal subjects (42 + 12% vs 29 + 10%, p < 0.05). The left atrial work was also significantly greater in patients with myocardial infarction (1690 + 717 mm Hgml) than in normal subjects (940 426 mm Hg-ml, p < 0.05). The ratio of active atrial emptying to left ventricular stroke volume and left atrial work were significantly related in both normal subjects and patients with myocardial infarction (y = 0.72, p < 0.01). The left ventricular ejection fraction correlated inversely with left atrial work (y = -0.5, p < 0.05). Left atrial work also showed a significant linear correlation with left atrial volume before active atrial emptying (y = 0.82, p < 0.01).We conclude that the left atrial contribution to left ventricular function is increased in patients with remote myocardial infarction. This left atrial contribution to the left ventricle is attributed to the FrankStarling mechanism in the left atrium.LEFT ATRIAL function and its hemodynamic importance for overall cardiac performance have been discussed.' 1-3 The left atrium may serve as a conduit for the passage of blood from the pulmonary veins to the left ventricle during early left ventricular filling, as a reservoir for storing blood during left ventricular systole, and as a contractile chamber for augmentation of left ventricular filling. Understanding each of these functions and the contribution of the left atrium to left ventricular function in normal and diseased hearts is important.In this report, we analyze left atrial pressure-volume relationships in patients with remote myocardial infarction and discuss the importance of left atrial function. MethodsData were obtained during diagnostic cardiac catheterization in two groups of patients. The normal group consisted of eight patients who had no coronary, valvular or congenital heart disease and were hemodynamically normal. These patients were referred for diagnostic cardiac catheterization to evaluate chest pain. The myocardial infarction group consisted of 10 patients who had a documented remote transmural myocardial infarction, and no other associated heart disease. The clinical data for each patient are listed in medications were discontinued for at least 2 days before the study, except for sublingual nitroglycerin, which was allowed for anginal attack, but withheld 12 hours before the study. A Millar catheter-tip micromanometer (Model PC-484A, pigtail) was used for pressure measurement and cineangiography. The transducer was calibrated electronically against mercury at the beginning of each study. The zero shift during the proc...

Background-Increased vascular oxidative stress induced by hyperlipidemia may alter the phenotype of vascular smooth muscle (SM) cells and play a crucial role in the progression of atherosclerosis. To clarify the mechanisms underlying vascular dysfunction and oxidative stress in hypercholesterolemia, we compared the effects of antioxidant probucol with those of pravastatin on aortic stiffness, phenotypic modulation, oxidative stress, and NAD(P)H oxidase essential subunit p22 phox expression in aortic medial SM cells of cholesterol-fed rabbits by using color image analysis of immunostained sections. Methods and Results-Japanese white male rabbits were fed either normal chow or 1% cholesterol diet for 14 weeks. After the first 7 weeks, cholesterol-fed rabbits were further divided into 3 groups: those fed with cholesterol feed only and those additionally given pravastatin (10 mg/d) or probucol (1.3 g/d) for the last 7 weeks. Within 7 weeks of treatment, probucol improved aortic stiffness more effectively than did pravastatin, inhibiting phenotypic modulation by selectively upregulating contractile-type SM myosin heavy chain isoform SM2 and by reducing both p22 phox and superoxide content in medial SM cells of cholesterol-fed rabbit aorta. No significant differences in cholesterol levels, superoxide content, and endothelial NO synthase levels in the intima, aortic morphology and fibrosis, and synthetic-type myosin heavy chain in medial SM cells were observed between the 2 drug-treated groups. Conclusions-These results suggest that oxidative stress and SM2 in medial SM cells might be important factors for vascular dysfunction, and strategies aimed at blocking NAD(P)H oxidase and upregulating SM2 may have therapeutic potential against the progression of atherosclerosis in hypercholesterolemia.

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Relations between left atrial contraction and left atrial early filling were studied in eight subjects with atypical chest pain from simultaneous left atrial pressure recordings and left atrial cineangiograms. The left atrial ejection phase was defined as the interval from the onset of the sharp systolic rise in left atrial pressure (a point) to the point of minimum left atrial volume (Vmin). The left atrial filling phase was divided into (a) the early filling phase, the period from Vmin to the nadir of left atrial pressure (x), and (b) the late filling phase, the period from x to the point of maximum left atrial volume (Vmax). During the early filling phase, when the left atrium filled as left atrial pressure diminished, approximately 37% of total atrial filling took place. There was a direct relation between left atrial volume measured at a and x points (r = 0.91, p less than 0.01). The extension fraction, measured as the ratio of filling volume during the early filling phase to minimum left atrial volume, was significantly correlated with ejection fraction, measured as the ratio of ejected volume (delta V) during ejection phase to left atrial volume at the a point (r = 0.97, r = 0.01). Both mean and peak filling rates of left atrial volume change during the early filling phase were directly proportional to the ejected volume, the ejection fraction, and the mean ejection rate of left atrial volume change during the ejection phase. Thus these results suggest that there is close interaction between left atrial contraction and left atrial early filling.

The relation between the left atrial systolic pressure waveform and left ventricular end-diastolic pressure was observed in 17 patients who underwent diagnostic cardiac catheterization. Left

Effect of changing afterload and inotropic states on inner and outer ventricular wall thickening. Am. J. Physiol. 263 (Heart Circ. Physiol. 32): H109-H116, 1992.--To study the differing behaviors of the inner (IH) and outer halves (OH) of the left ventricular (LV) free wall during an increasing afterload and changing inotropic states, we determined the LV pressure (LVP) and transmural (TM) and OH wall thickness (WTTM and WTOH) by sonomicrometry in 11 anesthetized dogs. The percent systolic wall thickening (% delta WT) and the fractional contribution (FC) were calculated. At rest, % delta WT of TM, IH, and OH were 22 +/- 1 (mean +/- SE), 33 +/- 3, and 13 +/- 2 (P less than 0.01 vs. IH), respectively. The FC of IH and OH were 74 +/- 5 and 29 +/- 4% (P less than 0.01 vs. IH), respectively. During increasing afterload by aortic constriction (AC) without drugs, % delta WT in IH was reduced to 22 +/- 2%, associated with unchanged % delta WT in OH (12 +/- 3%), whereas the FC of IH and OH were not altered from resting values. During AC with dobutamine infusion (3 micrograms.kg-1.min-1), the % delta WT and FC in each layer were not reduced from resting values. On the other hand, during AC with propranolol (2 mg bolus iv), the reduction of % delta WT in IH was greater (from 29 +/- 4 to 15 +/- 6%, P less than 0.01) than that in OH (from 11 +/- 2 to 10 +/- 3%; P less than 0.01 vs. IH). The FC in the IH was decreased (56 +/- 16%) by AC with propranolol, so that the difference in FC between IH and OH became insignificant (FCOH 40 +/- 13%, P greater than 0.1 vs. FCIH).(ABSTRACT TRUNCATED AT 250 WORDS)

Standard transthoracic ultrasound examination of the heart has provided increasingly better images since it was clinically introduced approximately 25 years ago. Although two-dimensional echocardiography is an established tool in clinical cardiology, the image qualities of conventional transthoracic approaches can sometimes be unsatisfactory for various reasons, such as patient obesity, chronic obstructive pulmonary disease, and chest wall changes with age. In these patients, transesophageal echocardiography can provide important diagnostic information because chest wall interference and intrathoracic attenuation are eliminated. Furthermore, the close vicinity of the heart and thoracic aorta to the echocardiographic sensor allows the use of higher-frequency, near-focused transducers, which produce better resolution and an improved signal-to-noise ratio. In addition, some structures that are poorly visualized by standard precordial echocardiography are better observed by the transesophageal approach, including wide areas of both atrial chambers, prosthetic valves, the left coronary arteries, and the thoracic aorta. Recently, color Doppler flow imaging with a transesophageal approach has increased available clinical diagnostic information and therefore expanded the diagnostic capabilities of cardiac ultrasound.In this brief review, we discuss the diagnostic possibilities and clinical advantages of transesophageal echocardiography based on its clinical application in more than 1,700 awake patients in our echocardiographic laboratory. Historical BackgroundAlthough transesophageal M-mode echocardiographyl-6 and transesophageal two-dimensional echo-cardiography7-9 were introduced in the late 1970s, acceptance of its use in awake patients has been slow, mainly due to methodological disadvantages for clin-

SUMMARY Left atrial function in patients with hypertensive heart disease was compared with that in control subjects. In patients with hypertensive heart disease, the time constant of left ventricular relaxation was significantly greater than that in controls (54 ± 18 vs 31 ± 16 msec; p<0.01). The ratio of left ventricular filling volume before atrial contraction (left atrial reservoir volume/left atrial emptying volume before atrial contraction, and conduit volume/flow volume from the pulmonary vein into the left ventricle) to left ventricular stroke volume was significantly smaller than that in controls (65 ± 13 vs 76 ± 7%; p<0.05). In patients with hypertensive heart disease, the ratio of reservoir volume to stroke volume was not significantly different from that in controls, while the ratio of conduit volume to stroke volume was significantly smaller than that in controls (43 ± 13 vs57 ± 9%;p<0.05). The latter ratio was inversely correlated with the time constant of left ventricular relaxation (r = -0.05, p<0.05). In patients with hypertensive heart disease, the ratio of left ventricular filling volume during atrial contraction to stroke volume was significantly larger than that in controls (35 ± 13 vs 24 ± 7%; p<0.05). The ratio of left ventricular filling volume during atrial contraction to stroke volume had a significant inverse correlation with the ratio of conduit volume to stroke volume (r = -0.84, p<0.001). In patients with hypertensive heart disease, left atrial work was significantly greater than that in controls (274 ± 101 vs 94 ±42 mm Hg ml; p<0.001). Thus, patients with hypertensive heart disease had impaired left ventricular diastolic filling before atrial contraction, which resulted in the decreased left atrial conduit volume. However, the left ventricular stroke volume was maintained by the increased left atrial emptying volume during atrial contraction. cardiac performance in the diseased heart has been considered previously.'" 10 The left atrium may serve as a conduit for the passage of blood from the pulmonary veins to the left ventricle during early left ventricular filling, as a reservoir for storing blood during left ventricular systole, and as a contractile chamber for augmentation of left ventricular filling. Understanding each of these functions and the contribution of the left atrium to left ventricular function in normal and diseased hearts is important. Electrocardiographic left atrial abnormalities" and the appearance of atrial gallop rhythm on cardiac ausculta- Received August 28, 1985; accepted February 12, 1986. tion 12 have been documented in patients with hypertensive heart disease. Recently, echocardiography has been used to observe left atrial function in hypertensive patients. 13 In these previous studies, the left atrial abnormalities were discussed in association with the abnormal diastolic function of the left ventricle, but further delineation of the significance and pathophysiology of the findings was not pursued.In the present study, the changes in reservoir, condu...