Effect of oxygen on breath markers of oxidative stress.

Supplemental oxygen is often administered to induce hyperoxia in nonhypoxic patients for indications such as chest pain, despite lack of evidence of clinical benefit. Induced hyperoxia is potentially toxic, since it may increase oxidative stress and peroxidative damage to deoxyribonucleic acid, lipids and proteins. The aim of this study was to establish whether supplemental oxygen induces oxidative stress in nonhypoxic subjects. Breath markers of oxidative stress were measured in 31 healthy subjects before and after breathing 28% oxygen at 2.0 L x min(-1) via nasal prongs for 30 min while resting. The criterion standard of oxidative stress was the breath methylated alkane contour (BMAC), a three-dimensional plot of the alveolar gradients of C4-C20 alkanes and monomethylated alkanes produced by lipid peroxidation. Volatile organic compounds (VOCs) in breath were assayed by gas chromatography and mass spectroscopy, and the BMACs before and after oxygenation were compared. Following oxygenation, there was a significant increase in mean volume under the curve of the BMAC and in alveolar gradients of three VOCs: 3-methyltridecane, 3-methylundecane and 5-methylnonane. Breath markers of oxidative stress were significantly increased in normal volunteers breathing supplemental oxygen for 30 min.

Assessment of acute right ventricular dysfunction induced by right coronary artery occlusion using echocardiographic atrioventricular plane displacement.

Right ventricular (RV) systolic function analysis by echocardiography has traditionally required RV endocardial border definition with subsequent tracing and is often inaccurate or impossible in technically poor studies. The atrioventricular plane displacement (AVPD) method attempts to use the descent of the tricuspid annular ring, a reflection of the longitudinal shortening of the right ventricle, as a surrogate marker for RV systolic function. We hypothesized that RV ischemia induced during right coronary artery occlusion proximal to the major right ventricular branches would result in severe right ventricular systolic dysfunction detectable by the AVPD method. During this pilot study, seven patients undergoing elective proximal RCA angioplasty had echocardiographic measurement of RV AVPD performed at baseline (i.e., immediately prior to RCA balloon inflation), during the last 30 seconds of first RCA balloon inflation, and at 1 minute after balloon deflation (recovery). Lateral and medial RV AVPD were significantly reduced from baseline values during intracoronary balloon inflation. (Lateral: 2.45 cm +/- 0.22 vs 1.77 cm +/- 0.13, P < 0.001; medial: 1.46 cm +/- 0.37 vs 1.28 cm +/- 0.32, P < 0.05). Additionally, lateral and medial RV AVPD significantly returned towards baseline values during recovery. (Lateral: 2.39 cm +/- 0.20, P < 0.001; medial: 1.58 cm +/- 0.27, P = 0.01). At baseline, all lateral RV AVPD values were > 2.0 cm, whereas during balloon inflation all were < 2.0 cm. No such clear distinction was found in medial RV AVPD values. Proximal RCA angioplasty is associated with a significant reduction in lateral and medial RV AVPD. Thus RV AVPD may serve as a marker for RV systolic dysfunction.

Spontaneous intramural atrial hematoma presenting as a left atrial mass.

We describe an unusual case of spontaneously occurring intramural atrial hematoma with no communication with either atrium. The diagnosis of left atrial mass was made from transthoracic echocardiography. Subsequent examination with transesophageal echocardiography confirmed a large mass essentially filling the whole left atrium but failed to provide an etiologic diagnosis, which was eventually made at surgery.

An electrocardiographic algorithm for the prediction of the culprit lesion site in acute anterior myocardial infarction.

BACKGROUND: Although the 12-lead electrocardiogram (ECG) has been found useful in identifying the left anterior descending (LAD) coronary artery as the infarct-related artery in acute myocardial infarction (MI), it has traditionally been felt to be incapable of localizing the culprit lesion within the LAD itself. Such a capability would be important, because anterior MI due to proximal LAD lesions carry a much worse prognosis than those due to more distal or branch vessel lesions. HYPOTHESIS: This study investigated whether certain ECG variables--especially an ST-segment injury pattern in leads aVL and/or V1--would correlate with culprit lesion site, and an ECG algorithm was developed to predict culprit lesion site. METHODS: The initial ECGs of 55 patients who had undergone cardiac catheterization after an anterior or lateral MI were reviewed to identify the leads with an ST-segment injury pattern; the corresponding catheterization films were then reviewed to identify the location of the culprit lesion; and these separate findings were then compared. RESULTS: The sensitivity and specificity of an ST-injury pattern in aVL in predicting a culprit lesion before the first diagonal branch were 91 and 90%, respectively; the same values in predicting a lesion prior to the first septal branch were 85 and 78%. ST-segment elevation in V1, on the other hand, was a much less sensitive and specific predictor of a preseptal lesion. Overall, our algorithm correctly identified the culprit lesion location in 82% of our patients. CONCLUSION: Based on our findings, we conclude that a ST-segment injury pattern in aVL during an anterior myocardial infarction predominantly reflects a proximal LAD lesion and therefore constitutes a high-risk finding.

Anomalous origins of the left coronary arteries from the right sinus of valsalva with an unusual course.

We report and attempt to classify a previously undescribed coronary artery anomaly. Our patient had all three coronary arteries arising from a common ostium in the right sinus of Valsalva, with an unusual distribution to the left coronary artery system: the anomalous left circumflex system taking an intraseptal (intramyocardial) course and the anomalous left anterior descending system taking an interarterial (between the great vessels) course.

Estimation of left ventricular systolic function by nonvolumetric echocardiographic analysis in subjects with poor left ventricular visualization: a pilot study.

BACKGROUND: Accurate assessment of left ventricular (LV) systolic function is an essential requirement in clinical cardiology. Several echocardiographic methods provide quantitative analysis of LV volumes and ejection fraction (EF) based on the precise tracing of endocardial borders. Often, however, technically limited studies prohibit such direct analysis, and alternative techniques must be applied. HYPOTHESIS: Nonvolumetric echocardiographic methods which do not require endocardial edge definition and tracing may accurately provide quantitative LV systolic function data. METHODS: A pilot study was conducted to validate and compare two recently described indirect echocardiographic methods of LV systolic function analysis, with LVEF by radionuclear cardiac angiography (RNCA). Thirty-two consecutive patients undergoing RNCA for clinical indications also underwent echocardiography within 24 h, with LV analysis performed by the techniques of (1) atrioventricular plane displacement (AVPD) and (2) mitral valve leaflet coaptation point to interventricular septum distance at end-systole (MVC-IVS). RESULTS: Thirteen patients had an echocardiogram with poor two-dimensional visualization of LV endocardial borders. One patient could not be evaluated by the MVC-IVS method and two others by the AVPD method because of technical limitations. Chi-square analysis to compare how each method could discriminate between an RNCA LVEF of < or > or = 50% demonstrated high correlations for the AVPD method (r = 0.6530, p < 0.0005) and the MVC-IVS method (r = -0.7029, p < 0.0001). Sensitivity, specificity, positive and negative predictive values, and test accuracy for the AVPD and MVC-IVS methods were 85 and 80%, 88 and 94%, 85 and 92%, 82 and 83%, and 83 and 87%, respectively. CONCLUSION: This pilot study demonstrates that both alternative echocardiographic methods may be useful in the assessment of LV systolic performance, even in the setting of poor LV endocardial border visualization. A larger study is warranted to apply and contrast these methods in different patient subsets.

Use of two-dimensional echocardiography in detection of an aberrantly placed transvenous pacing catheter.

The clinical usefulness and general ease of insertion of transvenous pacing catheters have made this procedure popular. It is sometimes difficult, yet important, to precisely locate the electrode tip. This report describes a patient in whom two-dimensional echocardiography was used to locate an aberrantly placed pacing catheter, whose position could not be established by conventional studies. Echocardiographic confirmation of the course taken by this pacing catheter has not been previously reported. The catheter was seen to pass from the aorta, through the aortic valve, into the body of the left ventricle.

Two-dimensional echocardiographic localization of a malpositioned pacing catheter.

The precise intracardiac localization of transvenous pacing catheter electrodes is sometimes difficult yet crucial to patient management. We describe a patient in whom standard indirect studies failed to locate a malpositioned pacing catheter. Two-dimensional (2-D) echocardiographic examination revealed its entire aberrant course, from the right atrium, across the interatrial septum, through the mitral valve and on to the apex of the left ventricle. The value of this technique is reviewed.

Relation of colloid osmotic pressure to arterial hypoxemia and cerebral edema during crystalloid volume loading of patients with diabetic ketoacidosis.

The effect of crystalloid volume loading on serum colloid osmotic pressure, arterial oxygen (Po2), alveolar-arterial oxygen gradient (A-aDo2), and cerebral lateral ventricle dimensions was prospectively studied in 18 patients with diabetic ketoacidosis. Serial measurements showed concomitant decreases in colloid osmotic pressure, hematocrit, arterial Po2 (p less than 0.001), and significant increases in A-aDo2 (p less than 0.001) during treatment. Serial echoencephalograms were taken of 11 of the 18 patients; each patient served as his or her own control. Nine of these 11 patients showed significant decreases in lateral ventricle width during treatment; seven patients showed the echoencephalographic "hash" marks characteristic of cerebral edema. Follow up studies showed resolution of these abnormalities. Volume loading with large amounts of crystalloid solution seems to produce an acute hypooncotic state that may cause the development of both subclinical pulmonary and cerebral edema.

Uremic pulmonary edema.

Pulmonary edema fluid analyses and hemodynamic evaluations were performed in two uremic patients with acute pulmonary edema. The colloid osmotic pressure of the pulmonary edema fluid ranged from 57 per cent to 93 per cent that of the serum. Although cardiac function was normal in both patients, the serum colloid osmotic pressure--pulmonary artery wedge pressure gradients were markedly reduced. Uremic pulmonary edema is the result of alterations of pulmonary intravascular Starling forces and increases in pulmonary capillary membrane permeability, allowing for the efflux of protein-rich fluid from the capillaries into the lung.