Predicting impaired cardiopulmonary exercise capacity in patients with atrial fibrillation using a simple echocardiographic marker

BACKGROUND

Exercise intolerance is a common symptom associated with atrial fibrillation (AF). However, echocardiographic markers that can predict impaired exercise capacity are lacking.

OBJECTIVE

This study aimed to investigate the association between echocardiographic parameters and exercise capacity assessed by cardiopulmonary exercise testing in patients with AF.

METHODS

This single-center prospective study enrolled patients with AF who underwent echocardiography and cardiopulmonary exercise testing to evaluate exercise capacity at a tertiary center for AF management from 2020 to 2022. Patients with valvular heart disease, reduced left ventricular ejection fraction, or documented cardiomyopathy were excluded.

RESULTS

Of the 188 patients, 134 (71.2%) exhibited impaired exercise capacity (peak oxygen consumption ≤85%), including 4 (2.1%) having poor exercise capacity (peak oxygen consumption <50%). Echocardiographic findings revealed that these patients had an enlarged left atrial end-systolic diameter (LA); smaller left ventricular end-diastolic diameter (LVEDD); and increased relative wall thickness, tricuspid regurgitation velocity, and LA/LVEDD and E/e' ratios. In addition, they exhibited lower peak systolic velocity of the mitral annulus and LA reservoir strain. In the multivariate regression model, LA/LVEDD remained the only significant echocardiographic parameter after adjustment for age, sex, and body mass index (P = .020). This significance persisted even after incorporation of heart rate reserve, N-terminal pro-B-type natriuretic peptide level, and beta-blocker use into the model.

CONCLUSION

In patients with AF, LA/LVEDD is strongly associated with exercise capacity. Further follow-up and validation are necessary to clarify its clinical implications in patient care.

Short- and medium-term prognosis of HIV-infected patients receiving intensive care: a Brazilian multicentre prospective cohort study

OBJECTIVES

The characteristics of critically ill HIV-positive patients and the causes of their admission to intensive care units (ICUs) are only known through retrospective and unicentric studies. This study aims to fill this knowledge gap.

METHODS

This is a prospective, multicentre cohort study of short- and medium-term prognostic factors. The setting consisted of ICUs of three tertiary referral hospitals from the three largest metropolitan areas in Brazil in the period January 2014 to November 2015. In all, 161 HIV patients over 18 years old were included.

RESULTS

The clinical data of the outcomes (ICU mortality, hospital mortality and 90-day survival) were extracted from medical records using the REDCap^®️ web-based form and analysed with the MedCalc^{® ️} application. Median age was 41.7 [interquartile range (IQR): 34-50] years, the Simplified Acute Physiologic Score 3 (SAPS 3) was 64 (IQR: 56-74), and the Sequential Organ Failure Assessment Score (SOFA) was 6 (IQR: 4-9) points. The main causes of admission were sepsis (54.5%) and acute respiratory failure (13.7%). ICU and hospital mortality rates were 32.3% and 40.4%, respectively. In a multivariate analysis, time until ICU admission ≥ 3 days (P = 0.0013), performance status (Eastern Cooperative Oncology Group score, P = 0.0344), coma (Glasgow Coma Scale ≤ 8 points, P = 0.0213) and sepsis (P = 0.0003) were associated with increased hospital mortality. Coma (P = 0.0002) and sepsis (P = 0.0008) were independently associated with 90-day survival.

CONCLUSIONS

Delayed ICU admission and the severity of critical illness determine the short- and medium-term mortality rates of HIV-infected patients admitted to the ICU, rather than factors associated with HIV infection. These results suggest that prognostic factors of HIV-infected patients in the ICU are similar to those of non-HIV-infected populations.

Diagnosis, impact and management of hyperhidrosis including endoscopic thoracic sympathectomy

INTRODUCTION

Hyperhidrosis is a disorder of excessive and uncontrollable sweating beyond the body's physiological needs. It can be categorised into primary or secondary hyperhidrosis based on its aetiology. Detailed history review including onset of symptoms, laterality of disease and family history are crucial which may suggest primary hyperhidrosis. Secondary causes such as neurological diseases, endocrine disorders, haematological malignancies, neuroendocrine tumours and drugs should be adequately examined and investigated prior to deciding on further management. The diagnosis of primary hyperhidrosis should only be made only after excluding secondary causes. Hyperhidrosis is a troublesome disorder that often results in social, professional, and psychological distress in sufferers. It remains, however, a treatment dilemma among some healthcare providers in this region.

METHODS

The medical records and clinical outcomes of 35 patients who underwent endoscopic thoracic sympathectomy for primary hyperhidrosis from 2008 to 2018 in Department of Cardiothoracic Surgery were reviewed.

RESULTS

The mean age of the patients was 27±10.1years, with male and female distribution of 18 and 17, respectively. Fifty-one percent of patients complained of palmar hyperhidrosis, while 35% of them had concurrent palmaraxillary and 14% had palmar-plantar-axillary hyperhidrosis. Our data showed that 77% (n=27) of patients were not investigated for secondary causes of hyperhidrosis, and they were not counselled on the non-surgical therapies. All patients underwent single-staged bilateral endoscopic thoracic sympathectomy. There was resolution of symptoms in all 35 (100%) patients with palmar hyperhidrosis, 13(76%) patients with axillary hyperhidrosis and only 2 (50%) patients with plantar hyperhidrosis. Postoperatively 34.3% (n=12) of patients reported compensatory hyperhidrosis. There were no other complications such as pneumothorax, chylothorax, haemothorax and Horner's Syndrome.

CONCLUSION

Clinical evaluation of hyperhidrosis in local context has not been well described, which may inadvertently result in the delay of appropriate management, causing significant social and emotional embarrassment and impair the quality of life of the subjects. Detailed clinical assessment and appropriate timely treatment, be it surgical or non-surgical therapies, are crucial in managing this uncommon yet distressing disease.

Derangement of heart rate variability during a catastrophic earthquake: a possible mechanism for increased heart attacks

At 1:47 AM on September 21, 1999, the middle part of Taiwan was struck by a major earthquake measuring 7.3 on the Richter scale. It has been shown that the mental stress caused by an earthquake could lead to a short- or long-term increase in frequency of cardiac death probably through activation of the sympathetic nervous system. The aim of this study was to investigate the effects of emotional stress on the autonomic system during an actual earthquake. Fifteen patients receiving a 24-hour Holter ECG study starting from 10+/-4 hours before the onset of the earthquake were included for the analysis of time- and frequency-domains of heart rate variability (HRV) at several time periods. A 24-hour Holter study recorded 2-6 months before the earthquake in 30 age- and sex-matched subjects served as the control group. Heart rate and the low frequency (LF) to high frequency (HF) ratio increased significantly after the earthquake and were attributed mainly to the withdrawal of the high frequency component (parasympathetic activity) of HRV. Sympathetic activation was blunted in elderly subjects > 60 years old. The concomitant ST-T depression observed in the Holter study correlated with a higher increment of LF as compared to HF components. The changes observed in HRV recovered completely 40 minutes following the earthquake. The derangement of HRV results from the withdrawal of the parasympathetic component and the arousal of sympathetic activity by the stressful earthquake. However, this autonomic derangement returned towards normal 40 minutes following the earthquake.

Inhomogeneity of myocardial perfusion in heart transplant recipients: evaluation with dobutamine thallium-201 SPECT

Progressive heterogeneity of thallium-201 single photon emission computed tomography (Tl-201 SPECT) in heart transplant recipients has been documented in Caucasians. However, in Chinese heart transplant recipients, a lower incidence of transplant coronary artery disease (CAD) has been noted than in Western transplant recipients. In this study, we examine whether heterogeneity of Tl-201 SPECT exists in Chinese transplant recipients. Dobutamine Tl-201 SPECT was performed in 40 heart transplant recipients and the inhomogeneity scores were calculated. The difference between the scores of transplant recipients surviving less than 12 months and those of control subjects were not statistically significant. One year after transplantation, the inhomogeneity score increased progressively. The scores of transplant patients in the second and third years after transplant were similar to those of single-vessel CAD patients. Three years after transplant the scores were greatly increased. Thus, our data suggest that the progressive nature of graft vasculopathy also exists in Chinese heart transplant recipients. The progressive Tl-201 abnormalities may be one of the early signs of graft vasculopathy.

Alterations of myocardial ultrasonic tissue characterization by coronary angioplasty in patients with chronic stable coronary artery disease

We conducted a study to delineate the alterations in the cyclic changes of myocardial ultrasonic integrated backscatter (IBS) in patients receiving angioplasty for chronic coronary artery disease. Ultrasonic tissue characterization (UTC) and dobutamine stress echocardiography were performed in 43 patients before and 24 h after angioplasty, as well as before the follow-up angiography 3 months later. For segments being normokinetic with ischemic burden, the blunted amplitude and increased nadir deviation of IBS cyclic modulation recovered soon after angioplasty. For dyssynergic segments with contractile reserve, the angioplasty rebuilt the amplitude before the wall motion recovered, but corrected the nadir deviation tardily. In both circumstances, the coronary restenosis abolished the initial restoration. Those nonviable segments persistently revealed large deviations and small weighted amplitudes irrelevant to coronary lesions. The progress of myocardial ischemia, the development of wall motion dyssynergy and, then, the loss of viability, show different patterns of alterations in UTC after alleviating coronary obstructions.

Accuracy of biphasic response, sustained improvement and worsening during dobutamine echocardiography in predicting recovery of resting myocardial dysfunction after revascularization: comparison with thallium-201 SPECT

To evaluate the accuracy of various types of wall motion response during dobutamine echocardiography (DE) in predicting functional recovery after revascularization, we studied 30 patients with stable coronary disease and left ventricular dysfunction by simultaneous DE and (201)Tl reinjection SPECT. Among 480 segments (16 segments/patient), 199 had abnormal wall motion at baseline and 167 were revascularized. The predictive value for recovery of function was 72% for a biphasic response, 61% for sustained improvement, 77% for worsening, and 27% for no change (p < 0.01 vs. each). Biphasic response had a sensitivity of 40% and specificity of 85%. Combining biphasic, sustained improvement and worsening responses, the sensitivity, specificity and accuracy were 76%, 65% and 71%, respectively. For (201)Tl SPECT, they were 90%, 65% and 78%, respectively. Thus, a biphasic response alone is of low sensitivity. Combination of biphasic, sustained improvement and worsening responses gives an accuracy rate comparable to that of (201)Tl reinjection SPECT in assessing functional recovery.

Intraventricular isovolumic relaxation flow patterns improve the predicting power of Doppler echocardiography for the left ventricular filling pressure in patients with anterior wall myocardial infarction

BACKGROUND AND PURPOSE

Previous studies have shown that left ventricular systolic asynchrony affects both the relaxation and filling phases of diastole. The purpose of this study was to delinate how the anterior wall dyssynergy influenced the intraventricular flow redistribution patterns during the isovolumic relaxation (IVR) period, which delineated the changes in diastolic suction performance and, therefore, determined the significant Doppler flow variables for predicting left ventricular filling pressure.

METHODS

Seventy-three patients with anterior wall myocardial infarction and dyssynergy were enrolled. Those who exhibited the whole IVR intraventricular flow redistributing toward the mitral apparatus, which indicated the reverse physiologic intraventricular pressure gradient in early diastole, were classified as group B, otherwise, as group A. The Doppler echocardiographic variables of mitral inflow were correlated with the left ventricular end-diastolic pressures (LVEDP).

RESULTS

With lower ejection fraction rate and more apical dyssynergy, the group B patients had much slower mitral flow propagation. For group A patients, the independent determinants for LVEDP were the ratio of mitral flow propagation rate to peak velocity in early diastole, the early mitral flow deceleration time and the IVR time, all occurring in early diastole. In contrast, the only independent determinant for LVEDP in group B patients was the ratio of mitral peak flow velocity in early diastole to that in late diastole.

CONCLUSIONS

The intraventricular IVR flow patterns could delineate how the left ventricular systolic dyssynergy influenced the diastolic process, and determine which echocardiographic variables were more useful for predicting LVEDP in patients with anterior wall myocardial infarction.

Comparison of ischemic patterns in myocardial bridge and syndrome X: evaluation by dobutamine stress echocardiography and stress thallium-201 SPECT

BACKGROUND AND PURPOSE

Ischemic patterns in patients with syndrome X are thought to differ from those in patients with myocardial bridge, because the mechanisms of coronary flow reduction in these two diseases are different. The aim of this study was to compare the ischemic patterns in patients with syndrome X and those with myocardial bridge through the use of dobutamine stress echocardiography (DSE) and stress thallium-201 single-photon emission computed tomography (SPECT).

METHODS

Twenty-six patients with typical angina and stress-induced ST-segment depression were enrolled. All patients underwent coronary angiography, DSE, and stress thallium-201 SPECT within 7 days after enrollment.

RESULTS

Of the 26 patients enrolled, 10 had myocardial bridge of the left anterior descending artery and 16 had syndrome X. Among patients with myocardial bridge, myocardial dyssynergy was found by DSE in five patients and reversible or fixed thallium-201 perfusion defects were found in four. Seven patients with myocardial bridge had reverse redistribution patterns on thallium-201 scintigraphy. In the 16 patients with syndrome X, myocardial dyssynergy was found by DSE in only one patient (p = 0.018 vs myocardial bridge group) and reversible or fixed thallium-201 perfusion defects were found in nine (p > 0.05 vs myocardial bridge group). Four patients with syndrome X had reverse redistribution patterns on thallium-201 scintigraphy. The resting left ventricular end-diastolic pressure was higher in patients with myocardial bridge than in those with syndrome X (17 +/- 4 vs 12 +/- 5 mm Hg, p = 0.02).

CONCLUSIONS

The most common ischemic patterns in patients with syndrome X were chest pain and stress-induced ST-segment depression, followed by myocardial perfusion defects. Dobutamine-induced dyssynergy was rare. Left ventricular end-diastolic pressure elevation and dobutamine-induced wall motion abnormalities were more common in patients with myocardial bridge than in those with syndrome X.

Assessment of the myocardial changes in heart transplant recipients without evident acute myocardial rejection by integrated backscatter: comparison with simultaneous dobutamine stress echocardiography and (201)thallium spect

Cardiomyocyte hypertrophy and interstitial fibrin deposition develop in cardiac allografts and contribute to the functional changes of transplanted hearts. We hypothesized that integrated backscatter (IBS) can detect these myocardial changes. A total of 32 heart transplant recipients with either no or mild acute rejection (International Society of Heart and Lung Transplantation grade IA) were enrolled in this study. IBS data of myocardium were collected immediately before simultaneous dobutamine stress echocardiography (DSE) and (201)thallium imaging. Coronary angiography and endomyocardial biopsy were also performed. Coronary angiography showed diffuse narrowing in 1 patient who also had abnormal results of IBS, DSE, and thallium results. In the other 31 patients with patent coronary arteries, there were 3 patients (10%) with abnormal DSE results, 19 patients (61%) with abnormal IBS patterns, and 16 patients (52%) with reversible thallium perfusion defects. Of the patients, 44% had cardiomyocyte hypertrophy and 56% interstitial fibrin deposition. There were significant differences in the prevalence of (201)thallium perfusion defects and serum cyclosporine levels between patients with and without abnormal IBS patterns. Pathologic changes were also associated with abnormal IBS patterns (p = 0.01). However, there was no association between abnormal IBS and DSE results. By multiple logistic regression analysis, the abnormal IBS patterns were associated inversely with serum cyclosporine level (p = 0.028). In conclusion, abnormal IBS patterns are associated significantly with perfusion heterogeneity and pathologic changes in heart transplant recipients without evident acute myocardial rejection. There is no association between abnormal IBS patterns and dobutamine-induced dyssynergy in these patients. IBS provides a noninvasive approach for detection of myocardial changes in transplanted hearts without evident acute rejection.

Ultrasonic tissue characterization with integrated backscatter during inotropic stimulation

Ultrasonic tissue characterization with integrated backscatter is an objective method to quantitatively define the physical state of the myocardium. To determine if backscatter imaging during inotropic stimulation could be used objectively to determine the myocardial viability and ischemia in patients with ischemic heart disease, the backscatter changes were examined in 23 patients with myocardial infarction during dobutamine stress two-dimensional (2-D) echocardiography. Coronary angiography was performed within 1 to 2 days after the stress test. The results of this study demonstrated that changes in backscatter variability correlated significantly with the wall motion changes in stress echocardiography during dobutamine infusion (p < 0.0001). In addition, it was shown that the backscatter changes were significantly different in various types of myocardial tissue. In 23 healthy control segments, the ultrasonic backscatter variability was preserved and unchanged during inotropic stimulation (p = NS). In 15 viable infarct zones, restoration or an increase in backscatter variability during low-dose dobutamine infusion was noted, this being lost when ischemia developing during high-dose dobutamine infusion (p < 0.01). In 9 nonviable infarct zones, the phase-weighted variation was usually < or = 0 and did not change significantly during inotropic stimulation, regardless of the patency of the infarct-related arteries. In 15 remote ischemic myocardial zones, the backscatter variability was preserved at the baseline level, did not change during low-dose dobutamine infusion, but decreased significantly during high-dose dobutamine stress (p < 0.01). In conclusion, dobutamine stress tissue characterization could offer an objective approach for the detection of myocardial viability and ischemia, and might be a useful adjunct to the conventional stress echocardiography.

Assessment of the coronary artery disease and systolic dysfunction in hypertensive patients with the dobutamine-atropine stress echocardiography: effect of the left ventricular hypertrophy

This study was performed to evaluate whether left ventricular hypertrophy (LVH) can influence the diagnostic accuracy of coronary artery disease (CAD) using the dobutamine stress echocardiography (DSE) in hypertensive patients. In addition to the detection of CAD, the relationship between systolic dysfunction and the quantitation wall motion scoring system of DSE was studied also. DSE was performed in 101 patients. There were 45 (45%) patients with a history of acute myocardial infarction. Twenty-eight patients (28%) had electrocardiographic LVH and 59 patients (58%) had echocardiographic LVH. A total of 74 patients (73%) had angiographically documented CAD defined as > or = 50% diameter stenosis. For the 56 patients without history of myocardial infarction, the diagnostic sensitivity, specificity, and accuracy in detecting CAD were not influenced by LVH defined by either electrocardiography or echocardiography. For the total patients, the diagnostic sensitivity, specificity, and accuracy in detecting multivessel disease were also not influenced by LVH defined by either method. The resting global wall motion score was correlated well with the left ventricular ejection fraction in patients with and without LVH (r = -0.70, p < 0.001 vs. r = -0.70, p < 0.001). When using the resting wall motion score of 24 as a cutoff value, the diagnostic sensitivity, specificity, and accuracy of systolic dysfunction (defined by left ventricular ejection fraction <40%) were 79, 86 and 85%, respectively. In conclusion, the diagnostic accuracy of CAD using the DSE was not affected by LVH in hypertensive patients. In addition to detection of coronary artery disease, the resting wall motion score of DSE was able to detect systolic dysfunction in patients with and without LVH.

Integrated backscatter for quantification and risk stratification of blood stagnation in left atrial appendages of patients with rheumatic mitral stenosis

This study was designed to quantify the blood stagnation in left atrial appendages (LAA) of patients with rheumatic mitral stenosis, and to stratify the risk of spontaneous echo contrast (SEC) for thrombus formation. A total of 45 patients were enrolled in this study. Thirty of the 45 patients had rheumatic mitral stenosis. All the above patients were evaluated for LAA contractility by transesophageal echocardiography. Acoustic density of the stagnant blood was assessed using the integrated backscatter (IBS) mode. Multivariate linear regression analysis showed that the significant independent variables determining relative IBS in LAA were the mitral valve area (p = 0.02) and the atrial fibrillation rhythm (p = 0.0003). In patients with mitral stenosis, the IBS in LAA correlated well with the presence of thrombus (p = 0.004) and SEC (p = 0.002). Using the relative IBS in LAA with 6.8 dB as the cutoff value, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of SEC formation in LAA was 83, 86, 95, 60 and 83%, respectively. Using the relative IBS in LAA with 10.0 dB as the cutoff value, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of SEC with thrombus formation in LAA was 80, 80, 67, 89 and 80%, respectively. In conclusion, the blood stasis in LAA can be objectively quantified using IBS. Utilizing different cutoff values, the acoustic densitometry in LAA enables identification of stagnant blood which represents a risk for the development of either SEC only or SEC with thrombus formation.

Comparison of simultaneous dobutamine echocardiography and thallium-201 stress-reinjection single-photon emission computed tomography in predicting improvement of chronic myocardial dysfunction after revascularization

Previous studies have shown that ultrasonic integrated backscatter is valuable in characterizing stunned myocardium. Recent investigations have demonstrated that resting cardiac cycle-dependent variation of integrated backscatter closely paralleled the contractile reserve in patients with chronic left ventricular ischemic dysfunction. The purpose of this study was to validate whether ultrasonic tissue characterization (UTC) compared with dobutamine stress echocardiography (DSE) and thallium-201 stress-reinjection single-photon emission computed tomography (Tl-SPECT) could predict reversible myocardial dyssynergy in patients with chronic coronary artery disease. Forty-eight patients with stable coronary artery disease underwent UTC, DSE, and Tl-SPECT simultaneously before successful coronary revascularization and were followed up with echocardiograms at rest >3 months later. Among the 58 investigated segments, the weighted amplitude, a composite parameter derived from the integrated backscatter power curve, was larger for those groups with greater functional recovery (p <0.001). For the persistent akinetic segments, the weighted amplitudes were small with large deviations of the nadir ratios that represented the asynchrony between the intramural contractile events and the global systole. Using the cut-off value 2.0 of the weighted amplitude, the sensitivity and specificity for predicting functional improvement after revascularization were both 82.8% (kappa = 0.66) and comparable to the sensitivity and specificity of DSE and Tl-SPECT. UTC, delineating the myocardial physical state and intramural contraction, can be a novel approach in predicting functional improvement of chronic dyssynergy after revascularization.

Role of coronary angiography in myxoma patients: a 14-year experience in one medical center

Cardiac myxoma is the most common form of primary heart tumor and often treated with surgical resection without a preoperative angiographic examination for fear of potential risk of sudden death. During the last 14 years, 24 of 38 patients with myxoma underwent coronary angiography. Coronary artery disease (CAD) and other abnormalities were found in 5. Our findings indicated that CAD is not uncommon among the myxoma patients, and coronary angiography should be performed preoperatively in all cases.

Power Doppler-derived speckle tracking image of intraventricular flow in patients with anterior myocardial infarction: correlation with left ventricular thrombosis

The abnormal spatial distribution of intraventricular flow is superior to clinical and two-dimensional (2-D) echocardiographic variables in predicting left ventricular thrombosis after myocardial infarction. Echocardiography was prospectively performed in 79 patients within 72 h after anterior wall myocardial infarction onset and repeated before discharge. The apical rotating flow pattern in color flow map was recognized as abnormal. By power Doppler echocardiography, the moving blood could generate speckle tracking images to delineate the intraventricular flow. A swirling flow pattern indicating the compartmentalization of left ventricular blood flow with some blood stagnant in the apical dyssynergic area was identified. The flow pattern shown by the speckle tracking image was superior to the color-flow map in correlating with left ventricular thrombosis. It implicated that the more the detail in which we can describe the blood flow pathway, the more information we can realize.

The significance of body weight change in non-Hodgkins lymphoma

BACKGROUND

The purpose of this study was to evaluate the effect of weight changes after completion of chemotherapy on the prognosis and survival of patients with intermediate and high grade non-Hodgkin's lymphoma.

MATERIALS AND METHODS

A retrospective analysis of data on patients from the TCOG T1488 protocol, a phase II study using CHOP in the treatment of intermediate and high grade lymphoma. From September, 1988 to December 1994, 138 adult patients had complete weight data for analysis. Weight gain in lymphoma patients after therapy significantly correlated with improved survival (Logrank test p = .0031). In patients with initial B symptoms, weight gain after therapy correlated with survival (Logrank test p = .0039), female patients (odds ratio = 6.2) were less likely to gain weight on treatment.

CONCLUSION

Weight gain after chemotherapy for lymphoma is a significant positive prognostic factor for survival.

Alterations in ultrasonic backscatter during intra-aortic balloon counterpulsation support in patients with acute myocardial infarction

Alterations of ultrasonic backscatter parameters have been evident in humans with myocardial infarction or ischemia. The backscatter variability could be restored in ischemic or stunned myocardium after reperfusion. The aims of this study were to determinate changes in regional myocardial ultrasonic backscatter during intra-aortic balloon counterpulsation (IABP) support in patients with acute myocardial infarction (AMI), and to evaluate whether backscatter imaging could be a functional guide of IABP support. A total of 9 patients with AMI were investigated during IABP support with a two-dimensional (2-D) ultrasonic backscatter imaging approach for parasternal short-axis view. Coronary angiography was performed in 6 of the 9 patients. A total of 21 vessel territories were studied in different modes of IABP support: 1:1, 1:2 and standby. Restoration of cyclic variation of backscatter after IABP support was demonstrated in 10 vessel territories. Failure of restoration of cyclic variation of backscatter after IABP support was noted in 6 vessel territories with severe coronary lesions (total or nearly total occlusion) or scar tissue. No changes of the ultrasonic backscatter were found in nonischemic vessel territories with patent coronary arteries or TIMI III coronary flow. In addition, the wall motion score did not change significantly with different IABP support. These results suggest that IABP could restore the cyclic variation of backscatter in ischemic myocardium. Myocardial anisotropy may play an influential role in the alterations of ultrasonic backscatter. We propose that ultrasonic backscatter could be a noninvasively functional guide of IABP use in patients with AMI.

Significance of dobutamine-induced ST-segment evaluation and T-wave pseudonormalization in patients with Q-wave myocardial infarction: simultaneous evaluation by dobutamine stress echocardiography and thallium-201 SPECT

The clinical significance of stress-induced ST-segment elevation and T-wave pseudonormalization in infarct-related leads is still controversial. Therefore, we conducted the present study to assess this issue using simultaneous dobutamine stress echocardiography (DSE) and thallium-201 single-photon emission computed tomography. A total of 119 patients with Q-wave myocardial infarction were enrolled in this study. There were 58 patients with (group I) and 61 patients without (group II) dobutamine-induced ST-T changes. Left ventricular ejection fraction was 43 +/- 13% in group I and 49 +/- 14% in group II (p <0.05). The baseline, low-, and peak-dose global wall motion scores were similar between these 2 groups (26.2 +/- 6.1 vs 26.2 +/- 6.3 [p = NS]; 24.1 +/- 5.3 vs 23.5 +/- 5.7 [p = NS]; 26.4 +/- 5.7 vs 26.7 +/- 6.1 [p = NS]). The sensitivity, specificity, and accuracy of these ST-T changes for detecting residual myocardial viability and ischemia documented by DSE in all patients were 50%, 53%, and 51% (for viability), and 47%, 48%, and 47% (for ischemia), respectively. The sensitivity, specificity, and accuracy of these ST-T changes for detecting a reversible perfusion defect documented by thallium-201 single-photon emission computed tomography were 51%, 54%, and 52%, respectively. In conclusion, dobutamine-induced ST elevation and/or T-wave pseudonormalization is associated with poor resting left ventricular function. These ST-T changes are not associated with residual myocardial ischemia and viability in the infarct area. Therefore, these electrocardiographic changes alone cannot be reliably considered as distinctive markers in formulating the therapeutic strategy of coronary intervention.

Nonsurgical transvenous retrieval of fractured implantable central venous access device

Implantable central venous access devices (ICVADs) are commonly used in patients with cancer and chronic diseases. Fracture and distal embolization of an ICVAD fracture is rare. A total of 1,006 central venous access procedures using ICVADs were done in National Taiwan University Hospital from January 1994 to December 1996. ICVAD fractures were noted in five of these 1,006 cases. All the fractured catheters were retrieved successfully by nonsurgical transvenous methods. The clinical manifestations were nonspecific palpitation or chest pain. The fracture site was always on the crossover point of the clavicle and the first rib on chest radiography. A pinch-off mechanism was suspected, and supported by scanning microscopy imaging. A deformed and elliptical shape of the fractured catheter site resulted from repeated wear and tear by the movement of the clavicle and first rib and associated muscle groups. The clinical course was benign if early retrieval of the distal fractured catheter by snare loop was possible. A more lateral position by a subclavian approach or an axillary approach for central venous access may avoid this procedure-related complication.

Ultrasonic tissue characterization in predicting residual ischemia and myocardial viability for patients with acute myocardial infarction

The identification of viable myocardium and residual ischemia in patients with acute myocardial infarction has important prognostic implications. The ultrasonic tissue characterization with integrated backscatter and dobutamine-atropine stress echocardiography were performed 8.3+/-3 days after AMI in 30 patients. After coronary angioplasty for the residual stenosis of infarct-related artery, both modalities were repeated. The parameter obtained from ultrasonic tissue characterization, phase-weighted variation, could differentiate the myocardium with residual coronary stenosis or nonviable myocardium from the viable myocardium without residual coronary stenosis (p < 0.001). Using the cutoff value of 5.8 dB, the sensitivity, specificity and accuracy for detecting viable myocardium without residual coronary stenosis were 75%, 100% and 90.2%, respectively. The phase-weighted variation of the viable infarction zone restored after the coronary stenosis was relieved. In contrast, the nonviable myocardium had a small phase-weighted variation that was irrelevant to the patency of the infarct-related artery. The ultrasonic tissue characterization may be used in identifying patients with acute myocardial infarction whose infarction zones are viable without residual ischemia.

Traumatic tricuspid regurgitation complicating endocarditis and right-to-left intracardiac shunt. A case report of successful operation

Tricuspid regurgitation caused by blunt chest trauma is generally quite tolerable for a long time in a clinical setting. This article reports on a 68-year-old patient suffering from progressive dyspnea after a blunt chest trauma having occurred 5 months previously. Flu-like symptoms occurred for several days before severe respiratory distress began upon the day of admission. Transesophageal echocardiographic evidence of endocarditis and right-to-left shunt across a patent foramen ovale (PFO) was demonstrated. Traumatic tricuspid insufficiency in this case was complicated with infective endocarditis and right-to-left intracardiac shunt. Cyanotic congestive heart failure occurred suddenly. He underwent emergency surgical repair with success. Based on the results presented herein, we recommend that early diagnosis be made for traumatic regurgitation and endocarditis by echocardiography so as to ensure therapeutic intervention.

New electrocardiographic criteria for the differentiation between counterclockwise and clockwise atrial flutter: correlation with electrophysiological study and radiofrequency catheter ablation

OBJECTIVE

To develop new electrocardiographic (ECG) criteria for the differentiation between counterclockwise and clockwise atrial flutters.

BACKGROUND

Traditionally, the ECG differentiation between counterclockwise and clockwise atrial flutters is based on the flutter wave polarity in the inferior leads. However, determination of flutter wave polarity is subjective and sometimes difficult, especially in flutter waves of undulating pattern.

PATIENTS

The study comprised 37 consecutive patients with drug resistant atrial flutter; 30 had counterclockwise and 17 had clockwise atrial flutter (10 had both forms of atrial flutter). The isthmus dependence was confirmed by entrainment study and catheter ablation. The ECG patterns of both types of atrial flutter were compared and the flutter wave polarity in the inferior leads was determined by four independent cardiologists.

RESULTS

The flutter wave polarity in the inferior leads appeared negative in 24, positive in one, and equivocal in five of the counterclockwise atrial flutters; polarity appeared negative in one, positive in 10, and equivocal in six of the clockwise atrial flutters. However, the aVF/lead I flutter wave amplitude ratio was > 2.5 in all counterclockwise but < 2.5 in all clockwise atrial flutters. The flutter wave nadirs in the inferior leads corresponded to the upstrokes in V1 in all counterclockwise atrial flutters, but corresponded to the downstrokes in V1 in all clockwise atrial flutters.

CONCLUSIONS

The flutter wave polarity in the inferior leads does not correlate well with the flutter wave rotating direction. However, counterclockwise and clockwise atrial flutters can be differentiated by new ECG criteria with high accuracy.

Assessment of coronary artery disease in women by dobutamine stress echocardiography: comparison with stress thallium-201 single-photon emission computed tomography and exercise electrocardiography

BACKGROUND

Dobutamine stress echocardiography (DSE) is sensitive and specific in detecting myocardial ischemia of male patients. However, there have been few reports about the use of DSE for the detection of coronary artery disease (CAD) in women.

METHODS

DSE was evaluated in 51 consecutive women who underwent concomitant quantitative coronary angiography. Forty-four of the 51 patients received stress thallium-201 single-photon emission computed tomography (SPECT), and 30 of the 51 patients had interpretable results (exercise level > or = 85% of age-predicted maximal heart rate) of treadmill exercise. Twenty-nine patients had angiographically documented CAD defined as > or = 50% diameter stenosis.

RESULTS

The overall sensitivity of DSE and stress 201Tl SPECT in detecting CAD was 93% and 79% (p = nonsignificant), and the specificity was 82% and 75% (p = nonsignificant), respectively. A combination of both tests increased the sensitivity (96%) at the expense of some decrease in specificity (60%). The agreement of DSE and 201Tl SPECT was 68% (30 of 44; kappa statistic = 0.35; p < 0.0001). The overall sensitivity, specificity, and accuracy in detecting CAD by treadmill exercise test and DSE were 71% vs 93% (p = nonsignificant), 44% vs 82% (p = 0.036), and 57% vs 88% (p = 0.003). In patients with abnormal results of treadmill exercise testing, the false-positive rate in detecting CAD was 2 (18%) of 11 in patients with abnormal results of DSE and 7 (88%) of 8 in those with normal results of DSE (p = 0.005). In patients with normal results of treadmill exercise testing, the false-negative rate in detecting CAD was 4 (100%) of 4 in patients with abnormal results of DSE and 0 (0%) of 7 in those with normal results of DSE (p = 0.003).

CONCLUSION

The diagnostic accuracy of DSE was similar to that of stress 201Tl SPECT in women. DSE was able to stratify female patients with either abnormal or normal results of treadmill exercise testing and to avoid unnecessary cardiac catheterization.

Comparison of S-T segment/heart rate slope with exercise thallium imaging and conventional S-T segment criteria in detecting coronary artery disease: effect of exercise level on accuracy

The S-T segment/heart rate (ST/HR) slope has been proposed as a more accurate electrocardiographic criterion for the diagnosis of coronary artery disease, but studies comparing the diagnostic value of the ST/HR slope with exercise thallium imaging are scant. The aims of this study were to assess the diagnostic accuracy of the ST/HR slope, conventional S-T segment criteria and exercise thallium imaging in detecting coronary artery disease and to evaluate the effect of exercise level on the sensitivity and specificity of these three techniques. Ninety consecutive patients underwent treadmill testing and exercise thallium single-photon emission computed tomography (SPECT) simultaneously. All 90 patients also underwent coronary angiography within 1 month of the exercise test. We found that exercise thallium SPECT had a significantly higher diagnostic accuracy than either the ST/HT slope or conventional S-T segment criteria (thallium imaging 82%, ST/HR slope 67%, conventional S-T segment criteria 63%). The overall accuracy of the ST/HR slope was slightly but insignificantly greater than conventional S-T segment criteria (ST/HR slope 67%, conventional S-T segment criteria 63%; p = 0.639). In 50 patients with a lower exercise level, defined as not achieving 85% of their maximal predicted heart rate, the accuracy of the ST/HR slope was insignificantly greater (ST/HR slope 72%, conventional S-T segment criteria 66%; p = 0.517). In 40 patients with adequate exercise, the accuracy rate was the same (60%) for both the ST/HR slope and conventional S-T segment criteria. We conclude that exercise thallium imaging is more accurate than the ST/HR slope in diagnosing coronary artery disease and that the accuracy of the ST/HR slope is marginally better than conventional S-T segment criteria only in patients with a lower exercise level, and not in those with adequate exercise.

Ultrasonic tissue characterization for coronary care unit patients with acute myocardial infarction

The ultrasonic integrated backscatter of myocardium changes in infarction and ischemia. On the third day after acute myocardial infarction, 30 patients underwent ultrasonic tissue characterization from the parasternal short-axis view. With a composite parameter, the phase-weighted variation, sensitivity, specificity, and accuracy for diagnosing multivessel coronary artery disease were 84.6%, 52.9% and 66.6%, respectively. Using 67 degrees as the cutoff value for the phase deviation of the backscatter power curve, the recanalization of the infarct-related artery could be detected with a positive predictive value of 77.7% and a negative predictive value of 66.6%. Ultrasonic tissue characterization is a feasible technique for detecting the multivessel coronary artery diseases and the recanalization of infarct-related artery for patients with acute myocardial infarction. The diminished cardiac cycle-dependent variation in integrated backscatter and increased phase deviation can differentiate patent coronary arteries from those coronary arteries with anatomically significant stenoses.

Simultaneous dobutamine stress echocardiography and thallium-201 perfusion imaging for the detection of coronary artery disease

To compare the diagnostic value of dobutamine stress echocardiography with dobutamine thallium-201 single-photon-emission computed tomography (SPECT) in detecting coronary artery disease, we performed both tests simultaneously on 93 patients who also underwent coronary arteriography. Dobutamine was infused at rates of 5, 10, 20, 30 and 40 microns/kg/min in 3-min stages. The left ventricle was divided into anteroseptal, posterolateral and inferior regions. Within each region, wall motion or perfusion abnormalities were classified as normal, ischemia or fixed defect. The response to stress was concordantly classified by both tests in 67 patients (72%, kappa = 0.48). Regional agreement for abnormalities was observed in 79% (kappa = 0.56) of the 279 regions analyzed. Dobutamine echocardiography detected 62 (93%) and thallium SPECT 60 (90%, p = NS) of the 67 patients with significant coronary artery disease (> or = 50% diameter stenosis). The specificity was 77 (20 of 26) and 81% (21 of 26), respectively. The accuracy was 88 and 87%, respectively. Combined the two tests gave a sensitivity of 97%, a specificity of 65% and an accuracy of 88%. The accuracy for detecting individual coronary stenosis with echocardiography was 83% for the left anterior descending artery, 84% for the right coronary artery and 73% for the left circumflex artery. With SPECT, it was 83, 87 and and 76%, respectively. In conclusion, dobutamine stress echocardiography and thallium SPECT provide a comparable accuracy for detection and localization of coronary artery disease, and for identification of regional myocardial abnormalities. Performing the two tests simultaneous is feasible but it adds limited value in detecting coronary artery disease.

Assessment of the functional significance of coronary artery stenosis by dobutamine-atropine stress echocardiography

This study was performed to evaluate whether dobutamine stress echocardiography (DSE) can provide any additional information regarding the location and severity of coronary artery disease (CAD) in an individual patient. DSE was performed in 233 patients with clinical manifestations of angina pectoris. There were 162 patients with angiographically documented CAD defined as > or = 50% diameter stenosis. The severity of coronary lesions was divided into three groups: 50-75, 76-90 and >90%. The diagnostic sensitivity in detecting left anterior descending artery (LAD) and right coronary artery (RCA) lesions was higher for lesion severity of>90% than of 50-75% (p = 0.01 for LAD and p < 0.05 for RCA). The diagnostic sensitivity in detecting CAD was highest among patients with proximal coronary lesions (89% for LAD, 64% for the left circumflex artery, and 81 % for the RCA). When lesion severity increased from 50-75 to >90%, wall motion scores at peak dose during dobutamine infusion increased from 12.3 +/- 4.3 to 18.4 +/- 5.4 (p = 0.003) in the proximal LAD lesion group and from 10.6 +/- 2.0 to 20.4 +/- 5.9 (p < 0.0001) in the mid-distal LAD lesion group. When lesion severity increased from 50-75 to >90%, wall motion scores at peak dose increased from 5.9 +/- 2.0 to 8.0 +/- 2.5 (p < 0.05) in the proximal RCA lesion group and from 5.2 +/- 2.1 to 8.1 +/- 1.9 (p < 0.05) in the mid RCA lesion group. However, the change in wall motion scores did not reach statistical significance in proximal and distal lesions of the left circumflex artery when lesion severity increased from 50-75 to >90%. The correlation coefficient between quantitative wall motion score and Gensini's score was 0.54 (p = 0.0001) in all patients and 0.6 (p = 0.0001) in patients without myocardial infarction. In conlcusion, the functional significance of lesion severity and distribution can be evaluated by DSE. Regional dyssynergy of LAD and RCA territories during peak-dose dobutamine infusion was most apparent at the stenotic level >90%.

Dobutamine stress echocardiography compared with exercise thallium-201 single-photon emission computed tomography in detecting coronary artery disease-effect of exercise level on accuracy

Dobutamine stress echocardiography (DSE) and exercise thallium-201 single-photon emission computed tomography (SPECT) were compared for the accuracy in detecting coronary artery disease (CAD) in 51 consecutive patients. Twenty-six (group 1) of the 51 patients achieved adequate exercise end points, and 25 (group 2) did not. There were 38 patients with angiographically documented CAD. The overall sensitivity of DSE and thallium-201 SPECT in detecting CAD was 92 and 76% (p = NS), and the specificity was 77 and 77% (p = NS), respectively. The sensitivity of DSE is the same as that of SPECT in group 1 (90 vs. 90%; p = NS) and higher than that of SPECT in group 2 (94 vs. 61%; p < 0.05). In patients with CAD without a history of acute myocardial infarction or pathological Q wave on resting electrocardiogram, the sensitivity of DSE is the same as that of SPECT in group 1 (82 vs. 82%; p = NS) and also higher than that of SPECT in group 2 (90 vs. 40%; p = 0.03). The sensitivity in detecting individual coronary artery lesions with DSE and thallium-201 SPECT was not affected by the exercise level. The agreement between DSE and thallium SPECT in detecting patients with CAD was 88% in group 1 (kappa = 0.69; p < 0.001) and 76% in group 2 (kappa = 0.45; p = 0.01). The agreement in detecting vascular territories with ischemia was 68% in group 1 (kappa = 0.30; p < 0.01) and 75% in group 2 (kappa = 0.33; p < 0.001). The agreement in detecting vascular territories with a scar was 87% in group 1 (kappa = 0.55; p < 0.001) and 85% in group 2 (kappa = 0.44; p < 0.001). In conclusion, the sensitivity and specificity of DSE in detecting CAD are similar to that of thallium-201 SPECT with an exercise level > or =85% of the maximal predicted heart rate. However, in patients who cannot exercise adequately, DSE is more accurate than thallium SPECT. The agreement between DSE and thallium SPECT in detecting patients with CAD and identifying ischemia of individual vascular territories is also affected by the exercise level.

Localizing individual coronary artery obstructions with the dobutamine stress echocardiography

The diagnostic accuracy of detecting individual coronary artery lesions using dobutamine stress echocardiography was evaluated in 206 patients with clinical manifestations of agnina pectoris. The sensitivity, specificity, and accuracy in detecting individual coronary artery lesions was described. The sensitivity was higher in the single-vessel group than in the double- or triple-vessel group. Furthermore, the sensitivity of dobutamine stress echocardiography in localizing vascular territories was greater for proximal segment lesions than for distal segment lesions. The increment of total score and score index at peak dose did not reach statistical significance between the left main lesion and the double-vessel lesions of left anterior descending artery and left circumflex artery (4.88 +/- 1.44 vs. 3.79 +/- 0.39, nonsignificant; 0.83 +/- 0.25 vs. 0.54 +/- 0.06, nonsignificant). In conclusion, although dobutamine stress echocardiography is sensitive for diagnosing coronary artery disease, localizing individual coronary artery lesions is less sensitive for triple-vessel disease and distal lesions.

Inoue balloon deformity and rupture during percutaneous balloon valvuloplasty

In the management of mitral stenosis, similar long-term results can be obtained by using either an Inoue balloon catheter or a double-balloon technique for percutaneous balloon valvuloplasty. There have been few reports concerning any deformity of an Inoue balloon. From January 1988 to June 1995, 263 procedures of either mitral or tricuspid valvuloplasty have been performed in this center. The Inoue balloon catheter technique was used for 245 procedures. A deformity of the Inoue balloon catheter was noted in 4 (1.6%) and actual rupture of deformed balloon occurred in one (0.4%). All deformities were found at the distal portion of the Inoue balloon. Valvular insufficiency became more severe after valvuloplasty in two cases. Following rupture of the balloon, neither arterial embolization nor perforation of the cardiac chambers developed. In conclusion, a deformity of the Inoue balloon, although rare, can develop during percutaneous balloon valvuloplasty. The deformity may portend balloon rupture if additional maximal dilatations are undertaken.

Successful treatment of acute myocardial infarction by thrombolytic therapy in a patient with primary antiphospholipid antibody syndrome

A dilemma must be faced when deciding whether or not to use thrombolytic therapy in patients with acute myocardial infarction and circulating antiphospholipid antibody. This report is about a patient whose infarct-related coronary artery was successfully revascularized by recombinant tissue plasminogen activator without any major bleeding complications. The nature of the infarct-related artery was described by the use of intravascular ultrasonography.

Dobutamine stress echocardiography for detecting coronary artery disease

To assess the value of dobutamine stress echocardiography (DSE) to detect coronary artery disease (CAD) and to compare the diagnostic accuracy between DSE and treadmill exercise test (TXT), 104 patients (mean age 58 +/- 12 years) presenting for coronary angiography were prospectively studied. TXT was performed according to the Bruce protocol. Dobutamine (5-40 micrograms/kg/min) was infused in 3-min stages. Digital echocardiograms were recorded on-line at baseline, during low- and peak-dose dobutamine infusion, and at recovery. An echocardiogram positive for CAD was defined as the one showing a new wall motion abnormality (WMA) induced by dobutamine. There were no major complications during the study. Significant CAD (> or = 50% diameter stenosis) was present in 17 of 30 patients who had normal echocardiograms at baseline. The sensitivity for detecting CAD was 76% by TXT and 94% by DSE, and the specificity was only 38% by TXT and 92% by DSE, respectively. Seventy-four patients had localized rest WMAs. Twenty-four had no significant CAD or lesions only confined to regions with abnormal rest wall motion, and 50 had disease remote from these regions. The sensitivity for detection of remote disease was 60% by TXT and 76% by DSE, and the specificity was 75% by TXT and 96% by DSE, respectively. In conclusion, DSE is a safe and accurate diagnostic tool for identifying CAD and for predicting the extent of disease in those who have localized rest WMAs.

Flow pattern of four pulmonary veins in a case with prolapsing left atrial myxoma. A case report

The authors report the flow pattern of the four pulmonary veins in a case with prolapsing left atrial myxoma. The early systolic flow was reversed, midsystolic forward flow was diminished, and diastolic forward flow was augmented and decelerated rapidly in all four pulmonary veins. This phenomenon is attributed to the dynamic movement of the myxoma.

Dobutamine stress echocardiography predicts early wall motion improvement after elective percutaneous transluminal coronary angioplasty

In 24 patients with chronic coronary artery disease, dobutamine stress echocardiography (DSE) was performed within 2 days before and after successful elective percutaneous transluminal coronary angioplasty (PTCA) in a blinded fashion. Patients with ischemic response on DSE before PTCA had significant improvement in the global peak-dose DSE score index after PTCA (1.62 +/- 0.35 to 1.40 +/- 0.29, p < 0.001), whereas patients without ischemic response had no improvement. The positive and negative predictive values of pre-PTCA DSE on early myocardial ischemia relief after angioplasty were 93% and 80%, respectively. In patients showing contractility recruitment during low-dose dobutamine infusion in the DSE before PTCA, there was significant improvement in the global resting wall motion score index in the DSE after PTCA (1.48 +/- 0.43 to 1.34 +/- 0.33, p = 0.004), while patients without contractility recruitment showed no improvement. Again, the positive and negative predictive values of pre-PTCA DSE on early hibernation recovery following angioplasty were 80% and 89%, respectively. In conclusion, DSE in patients with chronic, stable coronary artery disease accurately predicts wall motion improvement after successful angioplasty, and the expected improvement is safely demonstrated early after the procedure.

Detection of flavivirus antigens in purified infected Vero cell plasma membranes

The types of Kunjin virus-specified proteins present in purified Vero cell plasma membrane were studied. Immunofluorescence of unfixed Kunjin virus-infected whole cell monolayers, indicated that two structural proteins (envelope and prM) and three non-structural proteins (NS1, 3 and 5) were found at the plasma membrane. There was no obvious progressive accumulation of the observed antigens over the time periods between 8 to 24 h p.i. Thus SDS-PAGE analysis was performed using purified radiolabelled Vero cell plasma membranes. From the protein profiles, all five antigens detected by immunofluorescent staining were also present. In addition, two smaller molecular weight non-structural proteins NS4B and NS2B were also observed. Generally, all the non-structural proteins found in the purified plasma membranes were of the same molecular weights as those found in infected whole cell lysate. Interestingly, both the structural proteins, i.e., envelope (E) and prM proteins in the plasma membrane sample were of higher molecular weights as compared to the counterparts in the infected whole cell lysate. The envelope protein of purified extracellular Kunjin virus was also lower in molecular weight compared to the same protein in the plasma membrane.

Screening of carcinogens with the prophage lambda cIts857 induction test

The prophage lambda cIts857 induction test with Escherichia coli K12 envA uvrB as the lysogen has been successfully applied to the screening of sparingly water-soluble carcinogens that have been dissolved in dimethyl sulfoxide and metabolically activated with liver enzymes induced either with Aroclor 1254 or phenobarbital. Growth of noninduced lysogenic cells during the test was suppressed with ampicillin, with resultant increase of sensitivity of the test. The maximum inducing activity observed was about 50% of the complete induction level attained with water-soluble carcinogens that did not require metabolic activation. High sensitivity was achieved with the use of the lambda cIts857 prophage strain. In several instances where the Ames Salmonella-microsome test has failed to confirm the carcinogenicity of the respective carcinogens, this induction test has provided a better correlation. Of the carcinogens tested, only one false negative, namely, cyclophosphamide, was encountered. In contrast, the use of the wild-type prophage lambda strain resulted in low sensitivity. The adoption of the endolysin assay technique for the assessment of induction has greatly simplified the procedures and has permitted the screening test to be performed quickly and economically.