Wilfred Lam

Determination of left ventricular ejection fraction by visual estimation during real-time two-dimensional echocardiography

It has been shown that the measured reduction in the cross-sectional area of the left ventricle (LV), as viewed in the short axis, closely approximates its ejection fraction (EF). We assessed the reliability of using two-dimensional echocardiography (2DE) to visually estimate the EF during real-time viewing, without the need of digitizers, planimetry, or calculations. Twenty-five adult hospitalized patients with either suspected or known cardiac disease were evaluated prospectively. Each patient also had gated nuclear angiography during the same admission, and 14 had cardiac catheterization with left ventriculography. The EF was determined by 2DE using a visual estimate of the percent area reduction of the LV cavity in the short-axis view at the level of the papillary muscles. All 2 DE studies were read by two or more blinded reviewers, with a value for the EF to the nearest 2.5% determined by consensus. These values correlated closely to the values determined in all 25 patients with gated nuclear angiography (r = 0.927) and the 14 patients who had left ventriculography (r = 0.935). We believe that this method of visually estimating the LVEF will enable echocardiographers to easily use 2 DE for a reliable and instantaneous assessment of ventricular function, without the need of sophisticated analytical equipment.

Procainamide-lnduced polymorphous ventricular tachycardia

Seven cases of procainamide-induced polymorphous ventricular tachycardia are presented. In four patients, polymorphous ventricular tachycardia appeared after intravenous administration of 200 to 400 mg of procainamide for the treatment of sustained ventricular tachycardia. In the remaining three patients, procainamide was administered orally for treatment of chronic premature ventricular contractions or atrial flutter. These patients had Q-T prolongation and recurrent syncope due to polymorphous ventricular tachycardia. In four patients, the arrhythmia was rapidly diagnosed and treated with disappearance of further episodes of the arrhythmia. In two patients, the arrhythmia degenerated into irreversible ventricular fibrillation and both patients died. In the seventh patient, a permanent ventricular pacemaker was inserted and, despite continuation of procainamide therapy, polymorphous ventricular tachycardia did not reoccur. These seven cases demonstrate that procainamide can produce an acquired prolonged Q-T syndrome with polymorphous ventricular tachycardia.

Paroxysmal atrial fibrillation in the wolff-parkinson-white syndrome

Eighty-eight patients with preexcitation were studied to determine how 30 patients with documented spontaneous paroxysmal atrial fibrillation differed from 58 patients without this arrhythmia. Inducible reentrant tachycardia was present in 23 (77 percent) of the 30 patients with, versus 28 (48 percent) of the 58 patients without, atrial fibrillation (p less than 0.025). Heart disease was present in 13 (43 percent) of the 30 patients with, versus 15 (26 percent) of the 58 patients without, atrial fibrillation (not significant). Inducible reentrant tachycardia or heart disease, or both, were significant). Inducible reentrant tachycardia or heart disease, or both, were present in 29 (97 percent) of the 30 patients with, versus 34 (59 percent) of the 58 patients without, atrial fibrillation (p less than 0.0005). Of 51 patients with inducible reentrant tachycardia, 23 patients with atrial fibrillation did not differ from 28 patients without this arrhythmia with respect to clinical features and atrial, sinus nodal, or anomalous pathway properties, or cycle length of induced reentrant tachycardia. Spontaneous degeneration of induced reentrant tachycardia to atrial fibrillation was observed in 6 (26 percent) of 23 patients with, versus none of 28 patients without, atrial fibrillation (p less than 0.025). In summary, patients with preexcitation and documented spontaneous paroxysmal atrial fibrillation almost always have inducible reentrant tachycardia or heart disease, or both. It is likely that in many patients with inducible reentrant tachycardia, spontaneously occurring reentrant tachycardia relates to induction of atrial fibrillation. However, it is unclear why some patients with inducible reentrant tachycardia have atrial fibrillation and others do not. In many patients with organic heart disease, atrial fibrillation could relate to hemodynamic changes.

Reassessment of the effects of vasodilator drugs in primary pulmonary hypertension: Guidelines for determining a pulmonary vasodilator response☆

Patients with primary pulmonary hypertension develop hemodynamic changes characterized by an elevation in pulmonary artery pressure and pulmonary vascular resistance, and by a reduced cardiac output.’ There does not appear to be any relationship, however, between the magnitude of these changes and the duration of the illness.2 Consequently it becomes difficult to distinguish patients early in the course of their disease from those who have had the illness for many years. It has been suggested that the acute response to vasodilator drugs may be helpful in this regard.3 Upon making the diagnosis of primary pulmonary hypertension it is recommended practice to test the responsiveness of the pulmonary vasculature with vasodilator drugs given intravenously at the time of cardiac catheterization4 A substantial reduction in the pulmonary vascular resistance following drug administration has been interpreted as resulting from vasodilation within the pulmonary vascular bed,5*6 suggesting that patients who respond favorably are earlier in the course of their illness, still having reversible vasoconstriction.3 Recent successes in the use of vasodilator drugs for the treatment of essential hypertension have stimulated interest in the use of these drugs for patients with primary pulmonary hypertension as well. Demonstration of a fall in the pulmonary

Radionuclide regurgitant index: Value and limitations☆

The radionuclide regurgitant index, defined as left ventricular/right ventricular stroke counts obtained from gated equilibrium studies, has been reported to predict the presence and severity of left-sided valve regurgitation. This study evaluated the radionuclide regurgitant index in 100 patients in whom left-sided valve regurgitation was angiographically graded (0 to 4+) with regard to most severe mitral or aortic regurgitation. Regurgitation was graded 0 in 44 of the 100 patients, 1+ in 22, 2+ in 8, 3+ in 6 and 4+ in 20. The radionuclide regurgitant index was 0.9 to 1.5 in 51 patients, 1.6 to 2.4 in 23 and 2.5 to 12.0 in 26. The mean radionuclide regurgitant index was 1.34 in the group with no regurgitation and 1.60 in those with 1+, 2.01 in those with 2+, 2.80 in those with 3+ and 3.85 in those with 4+ regurgitation. There was a significant difference (p less than 0.05) in the radionuclide regurgitant index between patients with no regurgitation and each group with regurgitation and between groups with regurgitation separated by two or more grades of angiographic regurgitation. Twelve patients had a discordant radionuclide regurgitant index; their index either predicted clinically significant or severe regurgitation when they had no or trivial regurgitation, or predicted no or trivial regurgitation when they had clinically significant regurgitation. Eight of 10 patients with a left ventricular ejection fraction of less than 0.30 had a discordant index (p less than 0.0005). All three patients with mitral valve prolapse associated with frequent ventricular extrasystoles had a discordant index (p less than 0.0005).

Symptomatic spontaneous paroxysmal AV nodal block due to localized hyperresponsiveness of the AV node to vagotonic reflexes

Two apparently healthy patients had recurrent syncope with documented paroxysmal AV block. In both patients the site of AV block was demonstrated to be in the AV node. Coronary angiography (in both patients) and sustained deep inspiration (one patient) reproducibly initiated episodes of paroxysmal AV nodal block (identical to spontaneous episodes). Atropine abolished further attempts of AV block induction. Vagal hyperresponsiveness was limited to the AV node, since the interventions provoking paroxysmal AV nodal block produced only appropriate sinus slowing. This syndrome reflects hyperresponsiveness of the AV node to vagotonic reflexes, and exists as a clinically significant entity producing recurrent syncope.

Captopril as treatment for patients with pulmonary hypertension. Problem of variability in assessing chronic drug treatment.

We gave captopril, an angiotensin converting-enzyme inhibitor, to four patients with unexplained pulmonary hypertension to see if it would lower pulmonary arterial pressure or pulmonary vascular resistance. The patients were studied at rest and during supine bicycle exercise, before and after 48 hours of captopril treatment (up to 450 mg/day). During the treatment, each patient was monitored, with systemic and pulmonary pressures measured hourly, and cardiac output every two to four hours. We found no significant effect of captopril, either at rest or with exercise, on the cardiac output, pulmonary artery pressure, or pulmonary vascular resistance, measured at the end of 48 hours treatment. We noted, however, that during the 48 hour period, all patients showed pronounced swings in their pulmonary and systemic artery pressures and cardiac outputs that had no relation to the administration of captopril or time of day. We conclude that captopril appears to be ineffective in causing a sustained reduction in the pulmonary artery pressure or pulmonary vascular resistance in patients with primary pulmonary hypertension. It appears, however, that these patients experience spontaneous variability in their pulmonary resistance from hour to hour which needs to be further studied before a reliable assessment of long-term drug treatment can be made.

Comparative angiographic right and left ventricular volumes

Comparative angiographic right and left ventricular volumes and right and left ventricular ejection fractions have been reported in the same normal infants and children. This relationship was assessed in adult patients to determine if these pediatric observations persist in later life. Seventeen adults, who had both right and left ventricular angiograms and who had no demonstrable organic heart disease, were studied. Right ventricular end-diastolic volume ranged from 54 to 98 (76 +/- 14, mean +/- SD) cc/m2 and left ventricular end-diastolic volume ranged from 48 to 90 (70 +/- 12) cc/m2; p less than 0.03. Right ventricular end-systolic volume ranged from 22 to 47 (33 +/- 8.0) cc/m2 and left ventricular end-systolic volume ranged from 13 to 34 (22 +/- 5.3) cc/m2; p less than 0.00005. Calculated right ventricular stroke volume ranged from 31 to 60 (43 +/- 8.3) cc/m2 and left ventricular stroke volume ranged from 29 to 70 (48 +/- 11) cc/m2; p = NS. Calculated right ventricular ejection fraction ranged from 0.48 to 0.62 (0.57 +/- 0.04) and the left ventricular ejection fraction ranged from 0.57 to 0.84 (0.68 +/- 0.07; p less than 0.00005. Both right ventricular end-systolic and end-diastolic volumes were greater than left ventricular end-systolic and end-diastolic volumes. This resulted in decreased right ventricular ejection fraction compared to left ventricular ejection fraction. The difference between the two ventricles may be due to compliance, muscle mass, and anatomic configuration with a net result of one chamber more completely emptying than the other. Thus it appears that the relationships between right and left ventricular volumes noted in infancy and childhood persist in adult life.

M-mode echocardiography in left bundle branch block: Significance of frontal plane QRS axis

M-mode echocardiograms were obtained in 48 patients with complete left bundle branch block (LBBB). Of these 48 patients, 28 had LBBB with normal frontal plane QRS axis (-20 degrees to +90 degrees, mean +/- SD 18 degrees +/- 34 degrees), and 20 had LBBB with a left axis deviation (LAD) (-30 degrees to -60 degrees, mean +/- SD -48 degrees +/- 11 degrees). In the group with LBBB and normal axis, 25 patients had typical early mean +/- SD -48 degrees +/- 11 degrees). In the group with LBBB and normal axis, 25 patients had typical early systolic posterior septal motion characteristic of LBBB. Septal motion following early posterior septal motion (through the ejection period) was posterior in 24 patients (86%), anterior (paradoxical) in 2 (7%), and flat in 2 (7%). In the group with LBBB and LAD, 16 patients had the typical early systolic posterior septal motion; subsequent septal motion was posterior in 3 (15%), anterior (paradoxical) in 13 (65%), and flat in 4 (20%). Patients with LBBB and normal axis had a higher frequency of posterior septal motion, and patients with LAD had a higher frequency of anterior septal motion (p less than 0.001). The correlation of abnormal axis and paradoxical septal motion may be explained by the activation pattern producing LAD or by a septal disease process producing both abnormalities of axis and abnormal septal motion.

Equilibrium Radionuclide Gated Angiography in Patients With Tricuspid Regurgitation

Equilibrium gated radionuclide angiography was performed in 2 control groups (15 patients with no organic heart disease and 24 patients with organic heart disease but without right- or left-sided valvular regurgitation) and in 9 patients with clinical tricuspid regurgitation. The regurgitant index, or ratio of left to right ventricular stroke counts, was significantly lower in patients with tricuspid regurgitation than in either control group (range and mean +/- standard error of the mean 0.4 to 1.0, 0.7 +/- 0.1 versus 1.0 to 1.5, 1.3 +/- 0.1 and 1.0 to 2.9, 1.5 +/- 0.1, respectively, p less than 0.001). Time-activity variation over the liver was used to compute a hepatic expansion fraction which was significantly higher in patients with tricuspid regurgitation than in either control group (1.4 to 11.4, 5.8 +/- 1.0% versus 0.6 to 3.4, 1.9 +/- 0.3% and 1.0 to 5.1, 2.3 +/- 0.2%, respectively, p less than 0.001). Fourier analysis of time-activity variation in each pixel was used to generate amplitude and phase images. Only pixels with values for amplitude at least 7% of the maximum in the image were retained in the final display. All patients with tricuspid regurgitation had greater than 100 pixels over the liver automatically retained by the computer. These pixels were of phase comparable to that of the right atrium and approximately 180 degrees out of phase with the right ventricle. In contrast, no patient with no organic heart disease and only 1 of 24 patients with organic heart disease had any pixels retained by the computer. In conclusion, patients with tricuspid regurgitation were characterized on equilibrium gated angiography by an abnormally low regurgitant index (7 of 9 patients) reflecting increased right ventricular stroke volume, increased hepatic expansion fraction (7 of 9 patients), and increased amplitude of count variation over the liver in phase with the right atrium (9 of 9 patients).