Non-invasive assessment of left ventricular relaxation during atrial fibrillation using mitral flow propagation velocity

AIMS

To elucidate the usefulness of the early diastolic mitral flow propagation velocity (V(p)) obtained from colour M-mode Doppler for non-invasively assessing left-ventricular (LV) relaxation during atrial fibrillation (AF).

METHODS AND RESULTS

Ten healthy adult dogs were studied to correlate V(p) with the invasive minimum value of the first derivative of LV pressure decay (dP/dt(min)) and the time constant of isovolumic LV pressure decay (tau) at baseline, during rapid and slow AF, and during AF after inducing myocardial infarction. There were significant positive and negative curvilinear relationships between V(p) and dP/dt(min) and tau, respectively, during rapid AF. After slowing the ventricular rate, the average value of V(p) increased, while dP/dt(min) increased and tau decreased. After inducing myocardial infarction, the average value of V(p) decreased, while dP/dt(min) decreased and tau increased.

CONCLUSION

The non-invasively obtained V(p) evaluates LV relaxation even during AF regardless of ventricular rhythm or the presence of pathological changes.

Impact of left ventricular size on tissue Doppler and longitudinal strain by speckle tracking for assessing wall motion and mechanical dyssynchrony in candidates for cardiac resynchronization therapy

BACKGROUND

Myocardial dysfunction and left ventricular (LV) geometry deformation may reduce the accuracy of tissue Doppler imaging (TDI) in assessing myocardial contractility.

METHODS

In 92 patients with heart failure who underwent cardiac resynchronization therapy (CRT), we assessed the impact of LV end-diastolic volume on the accuracy of peak longitudinal velocity (TDI) and strain (epsilon(L) by speckle tracking) to assess regional wall motion and LV dyssynchrony.

RESULTS

Peak-epsilon correlated to normal (-13% +/- 6%, n = 259), hypokinetic (-10% +/- 5%, n = 347), and akinetic (-7% +/- 5%, n = 498, P < .0001) wall motion independent of LV size. In contrast, velocity failed to distinguish normal from dysfunctional segments in patients with severe LV dilatation (end-diastolic volume > 250 mL). The 12 standard deviation of time to peak systolic velocity and the opposing septal-lateral wall delay by strain and TDI failed to predict response to CRT, whereas the 12 segment standard deviation of time to peak epsilon correlated to end-systolic volume reduction (r = -0.39, P < .001).

CONCLUSION

Accuracy of TDI in assessing LV wall regional motion is limited in severely dilated ventricles and probably affects LV dyssynchrony measurement.

Safety of ultrasound contrast agents in stress echocardiography

Definity and Optison are perflutren-based ultrasound contrast agents used in echocardiography. United States Food and Drug Administration warnings regarding serious cardiopulmonary reactions and death after Definity administration highlighted the limited safety data in patients who undergo contrast stress echocardiography. From 1998 and 2007, 2,022 patients underwent dobutamine stress echocardiography and 2,764 underwent exercise stress echocardiography with contrast at the Cleveland Clinic. The echocardiographic database, patient records, and the Social Security Death Index were reviewed for the timing and cause of death, severe adverse events, arrhythmias, and symptoms. Complication rates for contrast dobutamine stress echocardiography and exercise stress echocardiography were compared with those in a control group of 5,012 patients matched for test year and type who did not receive contrast. Ninety-five percent of studies were performed in outpatients. There were no differences in the rates of severe adverse events (0.19% vs 0.17%, p = 0.7), death within 24 hours (0% vs 0.04%, p = 0.1), cardiac arrest (0.04% vs 0.04%, p = 0.96), and sustained ventricular tachycardia (0.2% vs 0.1%, p = 0.32) between patients receiving and not receiving intravenous contrast, respectively. In conclusion, severe adverse reactions to intravenous contrast agents during stress echocardiography are uncommon. Contrast use does not add to the baseline risk for severe adverse events in patients who undergo stress echocardiography.

The safety of deFinity and Optison for ultrasound image enhancement: a retrospective analysis of 78,383 administered contrast doses

BACKGROUND

The purpose of this retrospective analysis was to define the incidence of severe adverse events after exposure to ultrasound contrast agents.

METHODS

Data between January 1, 2001, and September 30, 2007, were collected using invited responses to an on-line web-based questionnaire from 1 general and 12 cardiac ultrasound laboratories. During a period of 4.5 +/- 2.4 years, a total of 66,164 doses of Definity (Lantheus Medical Imaging, North Billerica, MA) and 12,219 doses of Optison (GE Healthcare, Buckinghamshire, UK) were administered, reflecting contrast use in 5% of transthoracic and 28% of stress echocardiographic procedures. More than 10,000 doses were given to critically ill patients in intensive care unit settings or to patients with acute chest pain of suspected cardiac origin. The median age of patients who received an ultrasound contrast agent was 60 years, 49% were male, and the mean body mass index was 32 +/- 1.4 g/m(-2).

RESULTS

Severe reactions that were considered "probably" related to an ultrasound contrast agent developed in 8 patients (0.01%), all of whom were outpatients, and 4 (0.006%) of these were consistent with anaphylactoid reactions. There were no deaths reported. All patients recovered with treatment. No serious events were seen in inpatients.

CONCLUSION

This multicenter, retrospective analysis includes the largest number of doses of ultrasound contrast agents ever published and a large number of patients evaluated in a wide variety of settings, including the critically ill. It shows that these agents have a good safety profile in both cardiac and abdominal ultrasound applications. The incidence of severe adverse reactions to ultrasound contrast agents is no greater, and may be lower, than that reported for contrast agents commonly used in other cardiac imaging tests.

Longitudinal strain delay index by speckle tracking imaging: a new marker of response to cardiac resynchronization therapy

BACKGROUND

In heart failure patients with left ventricular dyssynchrony, contractility in delayed segments does not fully contribute to end-systolic function. We quantified this reserve of contraction related to mechanical dyssynchrony to predict response to cardiac resynchronization therapy by the strain delay index, which was defined as the sum of the difference between peak and end-systolic strain across 16 segments.

METHODS AND RESULTS

In 100 heart failure patients (ejection fraction=26+/-9%, QRS=154+/-29 ms, 94% in New York Heart Association class III), we studied left ventricular dyssynchrony before cardiac resynchronization therapy by the strain delay index using longitudinal strain by 2D speckle tracking and by the SD of time to peak myocardial velocity in 12 segments. The optimal cutoff value of the strain delay index to predict response to cardiac resynchronization therapy was determined in a retrospective group (n=65) and then confirmed in a validation group (n=35). Left ventricular end-systolic volume reduction at 3 months >15% (responder) occurred in 64 of 100 patients. In the retrospective group, the strain delay index but not the SD of time to peak myocardial velocity was greater in responders (n=42/65) than nonresponders (35+/-8% versus 19+/-7%, P<0.0001), and the optimal cutoff value to identify response to cardiac resynchronization therapy was 25%. In the validation group, strain delay index > or =25% identified 82% (18/22) of responders and 92% (12/13) of nonresponders. Among the entire population (n=100), strain delay index correlated with reverse remodeling in both the ischemic (r=-0.68, P<0.0001) and nonischemic (r=-0.68, P<0.0001) population.

CONCLUSIONS

Use of the strain delay index with longitudinal strain by speckle tracking has a strong predictive value for predicting response to cardiac resynchronization therapy in both ischemic and nonischemic patients.

Toward predictable repair of regurgitant aortic valves: a systematic morphology-directed approach to bicommissural repair

OBJECTIVES

Our purpose was to investigate a new approach to bicommissural repair of regurgitant aortic valves.

BACKGROUND

Repair of regurgitant aortic valves is not widely accepted, but interest is increasing, particularly for bicuspid valves. We hypothesize that a systematic, segmental approach to morphology and corresponding morphology-directed repair will improve decision making and success.

METHODS

From December 2001 to July 2007, a systematic surgical approach to valve analysis and bicommissural repair was applied prospectively to 63 consecutive patients with pure aortic valve regurgitation, mean age 40 +/- 12 years. Cusp, commissure, and root morphologies were analyzed sequentially by direct inspection. Each abnormality was corrected by corresponding morphology-directed repair procedures. Retrospectively, 2 echocardiographic indexes--of tissue pliability (change in systolic to diastolic area) and coaptation deficiency (conjoint and reference cusp heights vs. "annulus" diameter)--were developed to evaluate repairability.

RESULTS

Forty-two (67%) valves were repaired and 21 (33%) replaced. Regurgitation was related primarily to cusp (prolapse, restriction) and commissure (splaying) morphology; root pathology was less important. Morphology-directed repair included cusp maneuvers in all, commissural maneuvers in 71%, and root procedures in 33%. Restriction and cusp tissue deficiency limited repairability. Echocardiography reflected this in greater tissue pliability of successfully repaired valves compared with replaced ones (conjoint cusp 61 +/- 16% vs. 34 +/- 17%; reference cusp 65 +/- 16% vs. 42 +/- 16%; p = 0.0001) and less coaptation deficiency (1.06 +/- 0.24 for repaired and 1.27 +/- 0.19 for replaced valves; p = 0.002).

CONCLUSIONS

Systematic segmental analysis of morphology and a logical morphology-directed surgical approach facilitate aortic valve repair. Initial application of this paradigm suggests sufficient mobile cusp tissue is a key determinant of repairability.

Longitudinal rotation: an unrecognised motion pattern in patients with dilated cardiomyopathy

BACKGROUND

Heart failure patients who are candidates for CRT frequently display longitudinal rotation (LR) - a swinging motion of the heart when imaged in a horizontal long-axis plane.

OBJECTIVES

To identify the magnitude and predictors of LR in patients with ischaemic (ICM) and idiopathic dilated (DCM) cardiomyopathy, and to assess predictive value of LR in patients undergoing cardiac resynchronisation therapy (CRT).

DESIGN AND SETTING

A retrospective study in a tertiary heart care setting.

METHODS

Echocardiography was performed in 45 ICM and 41 DCM patients who were CRT candidates and 16 control subjects. Global LR, segmental strains and segmental LR were assessed from echocardiograms using speckle tracking. Repeat echocardiography >40 days after the beginning of CRT was performed in 64 patients.

RESULTS

While DCM patients with QRS duration of both <130 ms and > or =130 ms displayed significant clockwise LR (p<0.001 for both vs 0), ICM patients and control subjects had LR that did not differ from 0. The most significant LR predictor was end-diastolic volume (p<0.001) followed by the absence of ischaemia (p<0.001) and QRS duration (p = 0.05). DCM patients with prominent clockwise LR had lower septal but higher lateral strains than DCM patients with minimal LR, or ICM patients with counterclockwise LR. LR correlated with decrease of end-systolic volume in DCM (r = 0.49, p = 0.004), while no relationship was observed in ICM.

CONCLUSION

Clockwise LR is linked to presence of DCM, with the small impact of QRS duration. LR is a moderately strong predictor of end-systolic volume decrease during CRT in DCM.

Cardiac-resynchronization therapy in heart failure with narrow QRS complexes

BACKGROUND

Indications for cardiac-resynchronization therapy (CRT) in patients with heart failure include a prolonged QRS interval (> or =120 msec), in addition to other functional criteria. Some patients with narrow QRS complexes have echocardiographic evidence of left ventricular mechanical dyssynchrony and may also benefit from CRT.

METHODS

We enrolled 172 patients who had a standard indication for an implantable cardioverter-defibrillator. Patients received the CRT device and were randomly assigned to the CRT group or to a control group (no CRT) for 6 months. The primary end point was the proportion of patients with an increase in peak oxygen consumption of at least 1.0 ml per kilogram of body weight per minute during cardiopulmonary exercise testing at 6 months.

RESULTS

At 6 months, the CRT group and the control group did not differ significantly in the proportion of patients with the primary end point (46% and 41%, respectively). In a prespecified subgroup with a QRS interval of 120 msec or more, the peak oxygen consumption increased in the CRT group (P=0.02), but it was unchanged in a subgroup with a QRS interval of less than 120 msec (P=0.45). There were 24 heart-failure events requiring intravenous therapy in 14 patients in the CRT group (16.1%) and 41 events in 19 patients in the control group (22.3%), but the difference was not significant.

CONCLUSIONS

CRT did not improve peak oxygen consumption in patients with moderate-to-severe heart failure, providing evidence that patients with heart failure and narrow QRS intervals may not benefit from CRT. (ClinicalTrials.gov number, NCT00132977 [ClinicalTrials.gov].).

Using echocardiography in cardiac resynchronization therapy

Cardiac resynchronization therapy has become a therapeutic option for refractory heart failure. Several imaging techniques play an increasingly important role in patient selection during and after implantation. This manuscript reviews the current echocardiographic techniques available for guiding both patient selection and optimization of device programming following implantation.

Detection of pulmonary vein stenosis by transesophageal echocardiography: comparison with multidetector computed tomography

OBJECTIVE

The objective of this study is to compare the use of transesophageal echocardiography (TEE) vs multidetector computed tomography (MDCT) for detecting pulmonary vein stenosis.

BACKGROUND

Pulmonary vein isolation is increasingly used to treat atrial fibrillation. Pulmonary vein stenosis remains a potential complication of pulmonary vein isolation and ideal methods for detection of stenosis are still to be determined.

METHODS

Thirty-six subjects who underwent pulmonary vein isolation returned for follow-up MDCT and TEE. Percent diameter loss was reported for each pulmonary vein stenosis by MDCT. A 50% narrowing was considered as an indication of a stenosis. Pulsed-wave Doppler using TEE was used to measure peak velocities of all pulmonary veins.

RESULTS

Multidetector computed tomography and TEE were performed in all subjects (58 +/- 10 years) at 4 +/- 2 months after pulmonary vein isolation. Atrial fibrillation was present in 14% at time of follow-up. Multidetector computed tomography was able to evaluate all 4 (100%) pulmonary veins in 36 subjects, whereas full interrogation by TEE was possible in 138 (96%) of 144 veins. Pulmonary vein stenosis >50% by MDCT was present in 7 pulmonary veins. Analysis of the receiver operating curve for TEE showed that it had optimum detection of pulmonary vein stenosis at peak velocities approximately 100 cm/s with 86% sensitivity and 95% specificity. Area under the curve for TEE was 0.93. Clinically significant stenosis was observed in 2 subjects and was detected by both TEE and MDCT.

CONCLUSIONS

Transesophageal echocardiography was able to detect most pulmonary veins with good sensitivity and specificity in comparison to MDCT. Pulmonary veins may be visualized more frequently by MDCT; however, TEE provides additional data about the functional significance of a pulmonary vein stenosis.

Are Marfan Syndrome and Marfanoid Patients Distinguishable on Long-Term Follow-Up?

BACKGROUND

It is unclear whether late outcome differs for Marfan syndrome and marfanoid patients. Thus, we compared characteristics of Marfan versus marfanoid patients and their survival and requirement for reoperation.

METHODS

From 1978 to October 2003, 162 patients with a presumptive diagnosis of Marfan syndrome underwent operation. We recategorized them as confirmed Marfan (n = 122), marfanoid (n = 23), Ehlers-Danlos syndrome (n = 5), or other (n = 12). Patients categorized as marfanoid failed to meet the major criteria of Marfan syndrome. We compared characteristics of Marfan and marfanoid groups and assessed long-term survival and need for reoperation.

RESULTS

Marfan and marfanoid patients had similar demographics (women, 33% versus 39%; age, 39 +/- 13 versus 41 +/- 12 years; height, 186 +/- 12 cm versus 184 +/- 9.6 cm), valve pathophysiology (aortic regurgitation, 66% versus 58%; mitral regurgitation, 58% versus 62%), and aortic pathology (dilated, 40% versus 39%; dissected, 17% versus 13%). Overall hospital survival was 99.3% (144/145), and 10-year survival was similar at 82% in the Marfan and 100% in marfanoid groups (p = 0.13). Patients with aortic dissection (p = 0.001) and mitral valve replacement (p = 0.003) were at higher risk of death. Reoperation was more frequent after separate aortic valve-ascending aorta graft operations (p = 0.04), and among taller patients (p = 0.005). Of 24 Marfan patients with David root reimplantations, none has required reoperation.

CONCLUSIONS

Marfan and marfanoid patients have similar physical characteristics and postoperative survival, although reoperation was more frequent in Marfan patients. Surgery before occurrence of aortic dissection or mitral valve repair should reduce the risk of reoperation, but taller patients, irrespective of Marfan or gender, are more likely to require reoperation.

The Benefits of Biventricular Pacing in Heart Failure Patients with Narrow QRS, NYHA Class II and Right Ventricular Pacing

OBJECTIVE

To identify subgroups of heart failure patients who might benefit from biventricular pacing.

BACKGROUND

Cardiac resynchronization therapy (CRT) improves the quality of life, New York Heart Association (NYHA) functional class, and exercise capacity and decreases hospitalizations for heart failure for patients who have severe heart failure and a wide QRS. It is unclear if other populations of heart failure patients would benefit from CRT.

METHODS

One hundred forty-four consecutive heart failure patients who underwent CRT and completed 3 months of follow-up were reviewed. Demographic, echocardiographic, electrocardiographic, and clinical outcome data were analyzed to assess the relationship of functional class and QRS duration before device implantation to postimplant outcomes.

RESULTS

There were 20, 88, and 36 patients in NYHA functional class II, III, and IV, respectively. Thirty-four patients had right ventricular pacing and another 29 patients had a QRS duration < or = 150 ms. Patients who were in NYHA functional class II at baseline had significant improvement in left ventricular ejection fraction and indices of left ventricular remodeling after CRT. Similar significant findings were seen in the subgroup with right ventricular pacing at baseline after CRT. However, in the subgroup with a narrow QRS duration, there were no significant changes in the indices of left ventricular remodeling or in the NYHA functional class and there was a significant increase in the QRS duration. For the study cohort as a whole, an improvement in NYHA functional class after CRT correlated with a significant decrease in adverse clinical outcomes.

CONCLUSIONS

Heart failure patients who were in NYHA functional class II and those with right ventricular pacing appeared to benefit from CRT.