Thomas C. Gibson

Echocardiographic measurement of right ventricular volume.

The volume of the right ventricle can be determined angiographically from its projections in two mutually perpendicular planes. Echocardiographic techniques for measuring right ventricular volume, however, have been more difficult and less successful. In this study, a method was developed for calculating right ventricular volume from two intersecting cross-sectional echocardiographic views: the apical four-chamber and subcostal right ventricular outflow tract views. First, the areas and lengths of casts of 12 human right ventricles obtained at autopsy were directly measured in the chosen views. Actual cast volumes correlated best with a formula giving volume as 2/3 times the area in one view times the long axis in the other view. The degree of correlation was similarly high for calculations involving the area derived from either view and the length of the roughly orthogonal section. This relationship for right ventricular volume was then confirmed with two-dimensional echocardiographic images of hollow latex molds made from the casts (r = .95, p less than .0001). The significance of these findings is discussed in relation to angiographic results and models of the right ventricle.

Hydrodynamic compression of the right atrium: a new echocardiographic sign of cardiac tamponade.

The relationship of right atrial inversion, a previously undescribed cross-sectional echocardiographic sign, to the presence of cardiac tamponade was examined. We studied 127 patients with moderate or large pericardial effusions. Cardiac tamponade was present in 19 and absent in 104. Four patients with equivocal tamponade were excluded from analysis. Right atrial inversion was present in 19 of 19 patients with cardiac tamponade and 19 of 104 without cardiac tamponade (sensitivity, 100%; specificity, 82%; predictive value, 50%). The degree of inversion as quantitated by the area-corrected curvature did not improve the ability to discriminate between patients with and without cardiac tamponade. However, consideration of the duration of inversion by the right atrial inversion time index (duration of inversion/cardiac cycle length) and an empirically derived cut-off of 0.34 did improve the specificity and predictive value (100% and 100%, respectively) without a significant loss of sensitivity (94%). We conclude that right atrial inversion, particularly if prolonged, is a useful echocardiographic marker of cardiac tamponade that may be of particular diagnostic value when the clinical picture is unclear.

Diagnostic efficacy of 24-hour electrocardiographic monitoring for syncope.

The effectiveness of an open referral electrocardiographic monitoring service in identifying an arrhythmogenic cause for syncope was evaluated. Over 5 years, 7,364 patients of all ages underwent ambulatory 24-hour electrocardiographic (Holter) monitoring using a 2-channel recorder. Of these, 1,512 (20.5%) were referred because of syncope. During monitoring, 15 patients had syncope and 7 of the episodes were related to an arrhythmia, usually ventricular tachycardia. Presyncope was reported in 241 patients, with a related arrhythmia in 24. Thus, an arrhythmia-related symptom that could be diagnostic was present in only 2% of the patients monitored. However, syncope or presyncope without an associated arrhythmia might be considered a negative diagnostic clue and occurred in 225 (15%). High-grade atrioventricular block was present in 15 and ventricular tachycardia in 116; only 6 (5%) reported associated symptoms. An age-related incremental increase in atrial and ventricular arrhythmias was found. In 415 of the 1,004 patients (41%) aged 60 years or more, arrhythmias that are conventionally associated with sinoatrial disease were recorded. Using stringent diagnostic criteria, the sick sinus or tachybradycardia syndrome was present in 33 (3%). Many older patients (70%) were taking drugs that could be arrhythmogenic, hypotensive or both. It is concluded that an open referral 24-hour ambulatory monitoring service rarely results in identifying relevant symptom-related arrhythmias in patients with syncope. It records many asymptomatic arrhythmias that can compound rather than resolve the diagnostic problem in older patients, because the data obtained could lead to unnecessary therapy. An iatrogenic cause for syncope should always be considered.

Presumptive Tricuspid Valve Malfunction Induced by a Pacemaker Lead: A Case Report and Review of the Literature

A 23‐year‐old woman developed 3° AV block with syncope. Insertion of a permanent pacemaker lead was followed by the onset of a persistent murmur in late systole preceded by single or multiple clicks. The murmur was best heard at the left sternal edge, grade 3–4/6 with two major frequencies (60–250 Hz), increased with inspiration and on assuming the erect posture. It was considered to be tricuspid in origin and related to interference of the tricuspid valve apparatus by the pacemaker lead resulting in tricuspid regurgitation. No tricuspid valve prolapse or flutter was seen on echocardiography. Withdrawal of the pacemaker lead resulted in immediate disappearance of the new auscultatory findings. Review of the literature suggests that the appearance of such a murmur following pacemaker insertion could be associated with later complications in relation to tricuspid valve dysfunction. It is therefore recommended that, under these circumstances, permanent pacemaker leads should be appropriately repositioned.

Method for estimating right ventricular volume by planes applicable to cross-sectional echocardiography: correlation with angiographic formulas

Right ventricular (RV) volumes determined by echocardiography were compared with those measured using established angiographic formulas. RV cast displacement volumes were first correlated with data derived from radiographic images of the casts corresponding to standard angiographic RV views. Four established angiographic formulas (Ferlinz, Boak, Fisher and Thilenius) correlated well with cast volume, with the corrected prism method of Fisher showing a best fit (r = 0.98, y = 1.1 + 0.9 x, standard error of the estimate = 3.6). Cast volumes calculated using our echocardiographic formula were then examined relative to the volumes derived from radiographic images of the RV casts. Volumes calculated using the corrected area-length Thilenius formula correlated best with those obtained using our derived 2-dimensional echocardiographic formula (r = 0.96, y = 4.6 + 1.0 x, standard error of the estimate = 6.8). These data confirm that volume calculated using the suggested optimal echocardiographic formula correlates well with volume obtained using derived angiographic data. Accordingly, confirmation in humans by the use of angiography is a rational step.

The epidemiology of cardiac failure

Abstract This paper reviews available data related to the epidemiology of cardiac failure with special reference to mortality and morbidity in the United States. It is difficult to correlate such data because of multiple methods of collection in poorly defined populations and because most data are concerned with pathological data rather than with functional impairments. As a result, estimates of the prevalence of cardiac failure may lack validity. Available studies, which may be applied to the community, suggest that one per cent of the living population of the United States has been or is in cardiac failure, and that this disorder is most common in older people. Further studies of cardiac failure in defined populations are warranted in order to understand its epidemiology and clinical course. Standardized methods for collecting data and improved reporting are necessary in order to compare differences and trends in mortality and morbidity. The overall objective in the study of cardiac failure is to improve the quality of health as well as the duration of life for older persons.

Congenital aneurysms of the left atrium: recognition by cross-sectional echocardiography.

The two-dimensional echocardiographic features of three patients with congenital aneurysms of the left atrium are described. The aneurysm arose from the left atrial appendage in two patients and from the posterior left atrial wall in one. The aneurysms were characterized by their origin from an otherwise normal left atrium,- a well-defined neck, their position within the pericardial space, and distortion of the left ventricular free wall by the aneurysmal body. The differentiation of these structures from other abnormalities of the left atrium are also discussed. Two-dimensional echocardiography is a safe and reliable method for diagnosing congenital aneurysm of the left atrium, and such studies should be considered in any patient with an otherwise unexplained abnormality on the chest radiograph.

Unruptured sinus of valsalva aneurysm with right ventricular outflow obstruction diagnosed by two-dimensional and Doppler echocardiography

This report presents a case of an unusually large unruptured sinus of Valsalva aneurysm complicated by right ventricular outflow tract obstruction, right coronary artery occlusion and incomplete right bundle branch block. Two-dimensional and Doppler echocardiography were instrumental in preoperative diagnosis and postoperative follow-up.

A new echocardiographic model for quantifying three-dimensional endocardial surface area

A new technique for quantitatively mapping the three-dimensional left ventricular endocardial surface was developed, using measurements from standard cross-sectional echocardiographic images. To validate the accuracy of this echocardiographic mapping technique in an animal model, the endocardial areas of 15 excised canine ventricles were calculated using measurements made from echocardiographic studies of the hearts and compared with areas determined with latex casts of the same ventricles. Close correlation (r = 0.87, p less than 0.001) between these two measures of endocardial area provided preliminary confirmation of the accuracy of the maps. To further characterize the mapping algorithm, it was translated into computer format and used to map the surfaces of idealized hemiellipsoids. Areas measured with this mapping technique closely approximated the actual areas of idealized surfaces with a wide spectrum of shapes; maps were particularly accurate for ellipsoids with shapes similar to those of undistorted human ventricles. Also, the accuracies of area calculations were relatively insensitive to deviation from the assumed positions of the echocardiographic short-axis planes. Finally, although the accuracy of the mapping technique improved as data from more transverse planes were added, the procedure proved reliable for estimating surface areas when data from only three planes were used. These studies confirm the accuracy of the echocardiographic mapping technique, and they suggest that the resulting planar plots might be useful as templates for localizing and quantifying the overall extent of abnormal wall motion.

Blood pressure levels in acute myocardial infarction

Serial blood pressure recordings were taken for 72 hours in 112 patients with acute myocardial infarction and in 96 patients with cardiac ischemia, admitted to hospital no more than 6 hours after the onset of chest pain. During the first hour of admission 66 (31.7%) had a blood pressure recorded 160/100 or greater. By the sixth hour, without specific antihypertensive therapy, this number had fallen to 13 (6.3%). This fall was subsequently maintained with very similar trends for both acute myocardial infarction and cardiac ischemia. Such an early blood pressure fall in acute myocardial infarction may indicate that this is too labile a measurement to determine the need for, or efficacy of, antihypertensive therapy aimed at the preservation of myocardium. The hospital course and mortality rate of patients with acute myocardial infarction and early hypertension, as defined, did not differ significantly from the non-hypertensive group.