The value of two-dimensional echocardiography and Doppler examination in the assessment of hypertensive patients: a pilot study

Focused cardiac ultrasound in preoperative assessment: the perioperative provider's new stethoscope?

Focused cardiac ultrasound (FoCUS)—a simplified, qualitative version of echocardiography—is a well-established tool in the armamentarium of critical care and emergency medicine. This review explores the extent to which FoCUS could also be used to enhance the preoperative physical examination to better utilise resources and identify those who would benefit most from detailed echocardiography prior to surgery. Among the range of pathologies that FoCUS can screen for, the conditions it provides the most utility in the preoperative setting are left ventricular systolic dysfunction (LVSD) and, in certain circumstances, significant aortic stenosis (AS). Thus, FoCUS could help answer two common preoperative diagnostic questions. First, in a patient with high cardiovascular risk who subjectively reports a good functional status, is there evidence of LVSD? Second, does an asymptomatic patient with a systolic murmur have significant aortic stenosis? Importantly, many cardiac pathologies of relevance to perioperative care fall outside the scope of FoCUS, including regional wall motion abnormalities, diastolic dysfunction, left ventricular outflow obstruction, and pulmonary hypertension. Current evidence suggests that after structured training in FoCUS and performance of 20–30 supervised examinations, clinicians can achieve competence in basic cardiac ultrasound image acquisition. However, it is not known precisely how many training exams are necessary to achieve competence in FoCUS image interpretation. Given the short history of FoCUS use in preoperative evaluation, further research is needed to determine what additional questions FoCUS is suited to answer in the pre-operative setting.

Cost-effectiveness of electrocardiography vs. electrocardiography plus limited echocardiography to diagnose LVH in young, newly identified, hypertensives

BACKGROUND

In the United States, screening for left ventricular hypertrophy (LVH) in a newly diagnosed hypertensive patient is typically performed using electrocardiography (ECG). Echocardiography (echo) is a more accurate but also more expensive procedure. However, the introduction of limited echo within the past decade has made sonographic imaging of the heart less expensive and more available for routine screening.

METHODS

The cost per additional correct diagnosis of LVH for ECG vs. ECG plus limited echo (with limited echo utilized in patients without ECG evidence of LVH) was analyzed using decision analytic modeling. A structured literature search was used to parameterize model probabilities, and costs are based on the 2008 Medicare Physician Fee Schedule. The study population consisted of black and white cohorts ~50 years of age with new diagnosis of hypertension. Outcomes included short-term results of LVH screening and diagnosis, and the study perspective was health system.

RESULTS

Base-case results indicate each additional correct LVH diagnosis by ECG plus limited echocardiography instead of ECG cost $655 in the black cohort and $829 in the white cohort. Results in both cohorts were most sensitive to the cost of echocardiography. Simulation-generated cost-effectiveness acceptability curves demonstrated costs per additional correct diagnosis have a 90% likelihood of being below $993 and $1,420 in the black and white cohorts, respectively.

CONCLUSIONS

LVH detection by ECG plus limited echocardiography may be an economically feasible alternative to ECG due to increased accuracy. However, final recommendations require analysis of long-term effects on morbidity, mortality, quality of life, and subsequent treatment costs between the diagnostic approaches.

Feasibility and potential clinical utility of goal-directed transthoracic echocardiography performed by noncardiologist intensivists using a small hand-carried device (SonoHeart) in critically ill patients

OBJECTIVE

This study was designed to assess the clinical applicability of a small, handheld, portable transthoracic echocardiography device by noncardiologist intensivists.

DESIGN

Prospective, observational study. After 10 one-hour tutorials, intensivists performed a limited transthoracic echocardiography (TTE) (2-4 views, without Doppler or M-mode) examination with the 5.6-lb SonoHeart Echo System (SonoSite, Bethell, WA) on critically ill patients admitted to the surgical intensive care unit. After initial cardiac clinical assessment in 90 patients, a limited TTE was performed by an intensivist to assess left ventricular (LV) function and LV volume status. Each study was immediately reviewed and repeated by an echocardiographer to determine the technical quality of the TTE and the accuracy of the intensivist's interpretation. Data were analyzed and presented in proportions using descriptive statistics.

SETTING

Surgical intensive care unit of an academic medical center.

PARTICIPANTS

Ninety critically ill adult patients.

INTERVENTIONS

After initial cardiac clinical assessment, a limited TTE was performed by an intensivist to assess LV size and function, to rule out significant pericardial effusions, and to estimate circulatory volume.

RESULTS

Intensivists successfully performed a diagnostic limited TTE in 94% of patients and interpreted their studies correctly in 84%. Limited TTE provided new cardiac information and changed management in 37% of patients. TTE added useful information in an additional 47% of patients but did not alter immediate management. The mean "goal-directed TTE" acquisition time was 10.5 +/- 4.2 minutes.

CONCLUSION

After a brief formal training in using this handheld echocardiographic system in intensive care unit patients, surgical intensivists successfully performed and correctly interpreted a limited TTE in critically ill patients. Limited TTE provided new information and altered management in a significant number of patients. This study supports incorporating bedside goal-directed, limited TTE into intensivists' training programs.

Feasibility of point-of-care echocardiography by internal medicine house staff

OBJECTIVE

To determine whether internal medicine house staff with limited training in echocardiography can use point-of-care echocardiography to make simple, clinically important diagnoses.

BACKGROUND

Availability of small, portable ultrasound devices could make point-of-care echocardiography widely available. The training required to perform point-of-care echocardiography has not been established.

METHODS

Medical house staff participated in a 3-hour point-of-care echocardiography training program. Patients scheduled for standard echocardiography as part of clinical care underwent point-of-care echocardiography within 24 hours to assess four common clinically important diagnoses. Each standard echocardiogram was interpreted twice. Agreement (kappa) was calculated between point-of-care and standard echocardiography by using standard echocardiography as the gold standard and between the two interpretations of standard echocardiography.

RESULTS

Agreement (kappa) between point-of-care echocardiography and standard echocardiography was 75% (0.51) for left ventricular dysfunction (ejection fraction <55%), 79% (0.31) for moderate or severe mitral regurgitation, 92% (0.32) for aortic valve thickening or immobility, and 98% (0.51) for moderate or large pericardial effusion. Agreement between the two interpretations of standard echocardiography was 83% (0.63) for left ventricular dysfunction, 92% (0.68) for moderate or severe mitral regurgitation, 95% (0.62) for aortic valve thickening or immobility, and 97% (0.53) for moderate or large pericardial effusion.

CONCLUSIONS

Medical house staff with limited training in echocardiography can use point-of-care echocardiography to assess left ventricular function and pericardial effusion with moderate accuracy that is lower than that of standard echocardiography. Assessment of valvular disease and other diagnoses likely requires more training and/or experience in echocardiography.

Clinical utility and cost effectiveness of a personal ultrasound imager for cardiac evaluation during consultation rounds in patients with suspected cardiac disease

OBJECTIVE

To assess the clinical utility and cost effectiveness of a personal ultrasound imager (PUI) during consultation rounds for cardiac evaluation of patients with suspected cardiac disease.

METHODS

107 unselected patients from non-cardiac departments (55% men) were enrolled in the study. After the physical examination the consultant cardiologist performed an echocardiographic study with a PUI. The final report was given instantly to the referring physician. All patients subsequently underwent a study with a standard echocardiographic device (SED). For each patient the consultant cardiologist noted whether the findings of the PUI were adequate for final diagnosis. The total cost when full echocardiography was used was compared with the cost when the PUI was used. The time interval from request to diagnosis was also compared.

RESULTS

In 84 (78.5%) patients no further examination with an SED was regarded as necessary. Twenty three patients (21.5%) required a further detailed examination with the SED because of the need for haemodynamic information. There was an excellent agreement for the detection of abnormalities between the two devices (96%). The total cost was euro;132 per patient with the SED and euro;75 per patient with the PUI. According to this study, the use of the PUI can lead to a 33.4% reduction of total cost. The mean time from request to diagnosis at the authors' institution was four days for the SED and instantly for the PUI, for additional potential cost savings.

CONCLUSIONS

Immediate echocardiographic assessment during consultation rounds can lead to significant cost savings and can shorten the time to diagnosis.

Limited cardiac ultrasound examination for cost-effective echocardiographic referral

BACKGROUND

Although a standard echocardiogram is frequently requested and requires significant resources, few data exist on methods to improve referral for this examination. Therefore, we sought to determine the diagnostic value of a limited echocardiographic examination and to predict the cost-effectiveness of a limited imaging strategy on echocardiographic referral.

METHODS

A limited echocardiographic examination was reviewed for abnormalities and compared with standard echocardiographic findings. Assuming an imaging strategy in which a normal limited echocardiographic examination would negate the need for standard echocardiography, we calculated the diagnostic yields, the number of full echocardiographic studies eliminated, and the number of abnormal cases missed. We also stratified data by patient age (< or > or = 65 years), inpatient versus outpatient status, gender, referral diagnosis, and referring physician subspecialty.

RESULTS

In 151 outpatients, overall diagnostic yield was 47% (95% CI [39%, 55%]), and was lower in those younger than 65 years, in women, and in noncardiologist referral. In 155 inpatients, yields were 75% (95% CI [67%, 83%]) and were also related to age, but not to gender, diagnosis, and physician subspecialty. Sensitivity, specificity, negative and positive predictive values, and accuracy for the limited echocardiographic examination was 77%, 72%, 67%, 81%, and 75%, respectively. The limited imaging strategy negated 70% of studies in the outpatient group younger than 65 years, with a less than 5% chance of missing a clinically significant finding.

CONCLUSION

A limited echocardiographic imaging strategy is most cost-effective when used in young outpatients, where it can result in a substantial reduction in referral for standard echocardiography while rarely missing findings.

Experience with an ultrasound stethoscope

BACKGROUND

To test the diagnostic potential of the SonoHeart, a battery-powered hand-held ultrasound imaging device, in an outpatient clinic setting.

METHODS

A total of 114 patients with a variety of cardiac diseases were examined by 2 independent cardiologists with the hand-held device using the standard echocardiographic system (SE) as a reference. Global right ventricular (RV) and left ventricular (LV) function (scored as normal, mildly to moderately, or severely reduced) and internal cavity dimensions were assessed. Regional wall motion of 6 segments using a 2-point score (1 = normal wall motion, 2 = abnormal wall motion) was evaluated in 34 patients on-line.

RESULTS

There was a good agreement between the 2 imaging devices for evaluation of global LV (93%) and RV function (99%), regional wall motion (90%), dimensions of the LV (99%) and the RV (99%), and the left (96%) and right atria (99%). Furthermore, SonoHeart identified hypertrophic cardiomyopathy, pericardial effusion, and abnormalities of valves.

CONCLUSION

The SonoHeart device allows rapid and accurate diagnosis, whenever needed in the outpatient clinic.

Screening cardiac ultrasonographic examination in patients with suspected cardiac disease in the emergency department

BACKGROUND/OBJECTIVE

Our purpose was to evaluate the utility of a brief screening cardiac ultrasonographic (SCU) examination. We prospectively compared the SCU with conventional clinical evaluation in 124 emergency department (ED) patients with suspected cardiac disease. Furthermore, we assessed the impact and quality of SCU examinations as obtained by briefly trained ED personnel (EP).

METHODS

Patients underwent clinical evaluation by an ED physician and SCU examination by a sonographer or cardiologist. Patient disposition, hospital stay length, and the number of full echo examinations were compared with the presence of significant findings on SCU. In patients who received a full echocardiogram during hospitalization, results of the initial clinical examination were compared with results of the SCU examination in the diagnosis of significant findings. A similar analysis, but with quality assessment, was performed on only those SCU examinations acquired by 4 EP.

RESULTS

Of the 124 patients enrolled in the main study, 40 of 124 (32%) had significant findings on SCU. Of patients with abnormal SCUs versus normal SCUs, 16 of 40 (40%) versus 18 of 84 (21%) had hospital stay lengths >2 days (P < or =.05). Using the 36 inpatient full echo studies obtained for standard indications during hospitalization as a gold standard, initial clinical examination identified only 7 of 30 (23%) significant findings and had 16 false-positive diagnoses, whereas SCU identified 22 of 30 (73%) with 8 false positives. Although similar study results occurred with interpretation of 68 SCUs obtained by EP, quality was achieved in only 55% ED personnel versus 97% of sonographer-obtained SCUs (P <.05).

CONCLUSIONS

An SCU examination detects significant findings misdiagnosed on initial clinical evaluation in the ED and provides prognostic data regarding length of hospital stay.

Indications for limited echocardiographic imaging: a mathematical model

BACKGROUND

Few data exist on the magnitude of potential time savings obtained by using a limited echocardiographic (echo) imaging strategy on a referral population.

METHODS

A mathematical model of a limited echo screening strategy was devised that used as variables the length of the limited examination and the probability of detecting the referral diagnosis or a significant incidental finding, and assumed that any abnormality would mandate a full study. Data from prior echo population studies were used in the model as examples.

RESULTS

The model demonstrated a direct relation in time savings for populations with a low prevalence of disease and incidental findings. The model predicted that a limited echo imaging strategy could result in significant time savings when applied to certain specific referral populations.

CONCLUSIONS

The time savings of a limited echo screening strategy can be modeled as a function of the length of the limited screen and the presence of significant findings. This model may provide the framework in which future prospective studies can confirm indications for limited echo.

Feasibility of "limited" echo imaging: characterization of incidental findings

To evaluate the feasibility of limiting the extent of the echocardiographic examination without omitting significant incidental findings, we reviewed consecutive reports from full echo studies performed in a tertiary medical center with the following referral questions: "rule-out pericardial effusion" (n = 40) and "rule-out source of embolus" (n = 132). Specific limited echo imaging protocols were formulated without unnecessary imaging (that is, unrelated to the diagnostic question) or use of Doppler. The percentage of full echo studies with significant incidental findings was determined, categorized by patient age, and then recalculated by whether the specific limited imaging protocol could potentially detect any or all of the incidental findings. The percentage of cases with significant incidental findings was 45% and 36% in the "rule-out" pericardial effusion and source of embolus groups, respectively. This percentage was dependent on age <65 years versus > or =65 years (22% vs 42%, p < 0.005). Limited imaging protocols could identify > or =85% of cases with significant incidental findings. These data suggest that limited echo imaging may be feasible in certain patient groups and referral diagnoses.