Cross-sectional imaging identifies flow-mediated vasodilatation more accurately compared with longitudinal imaging.

OBJECTIVES: The purpose of this study was to evaluate cross-sectional imaging to longitudinal plane imaging for measurement of flow-mediated dilatation (FMD). BACKGROUND: Accurate and reproducible assessment of FMD as a measure of endothelial function has important implications. Conventional imaging of the brachial artery is in a longitudinal plane. However, the changes in vasodilatation seen are subtle and minimal (10%-20%) in healthy states with an even smaller change in diseased states, thus, affecting interobserver and intraobserver variability and reproducibility. METHODS: Nine healthy volunteers (5 men, 4 women) between the ages of 25 and 65 years had baseline FMD measurements done using both longitudinal and cross-sectional imaging. Brachial artery was occluded by inflating the sphygmomanometer cuff on the arm at a pressure of 150 mm Hg for 5 minutes. The artery was imaged continuously for 5 minutes postdeflation. The images were recorded digitally on a computer and analyzed for area and diameter changes by user-guided semiautomated boundary detection method described by our group earlier. RESULTS: The baseline measurements were normalized to 1.00 for both longitudinal and cross-sectional images. After cuff deflation, the mean longitudinal diameter increased to 1.10 +/- 0.04 versus 1.30 +/- 0.17 (P = .007) for the cross-sectional method. The mean longitudinal measurements were 85.7 +/- 13.9 pixels at baseline that increased to 94.3 +/- 13.1 pixels for a mean change of 8.6 +/- 3.1 pixels after cuff deflation, compared with a mean of 8577.4 +/- 2950.8 pixels that increased to 11120.5 +/- 3989.4 pixels for a mean change of 2543 +/- 1552 pixels by the cross-sectional method (P < .001). CONCLUSIONS: Cross-sectional imaging produced a much larger change in area and pixels compared with longitudinal imaging. This translates into greater sensitivity in detecting small changes produced by FMD.

Effect of obstruction on longitudinal left ventricular shortening in hypertrophic cardiomyopathy.

OBJECTIVES: We investigated the cause of the midsystolic drop (MSD) in left ventricular (LV) ejection velocities that are observed with hypertrophic cardiomyopathy (HCM) and severe obstruction. BACKGROUND: Dynamic obstruction is an important determinant of symptoms and adverse outcome. The MSD in velocity and flow occurs in patients with gradients >60 mm Hg. The nadir velocity in the LV occurs simultaneously with peak gradient. METHODS: We studied 36 patients with obstructive HCM and an MSD and compared them with 15 patients with HCM and no obstruction and with 25 age-matched normal control subjects. We measured LV ejection velocity proximal and distal to LV obstruction as well as tissue Doppler velocities and time intervals. RESULTS: The duration of contraction of both the septum and lateral wall is shorter in obstructed patients with the MSD than in nonobstructed HCM patients: septal contraction 203 +/- 68 ms vs. 271 +/- 41 ms (p < 0.001). Parallel reduction in the length of shortening was noted: 1.2 +/- 0.6 cm vs. 1.9 +/- 0.4 cm (p < 0.001). The ejection velocity nadir follows the septal and lateral peak velocities by 100 ms and 60 ms, respectively. The velocity nadir occurs as both walls rapidly decelerate to their premature termination: septal deceleration 79 +/- 35 cm/s2 vs. 48 +/- 21 cm/s2 (p < 0.001). With medical abolition of obstruction the MSD disappears and the duration and length of contraction normalizes. CONCLUSIONS: These data indicate that the MSD is caused by premature termination of LV segmental shortening and is a manifestation of systolic dysfunction.

Tako tsubo cardiomyopathy (transient left ventricular apical ballooning): case report of a myocardial perfusion echocardiogram study.

We are reporting a case of Tako tsubo cardiomyopathy (transient left ventricular apical ballooning) in the Western population identified by a perfusion echocardiogram that demonstrated perfusion defect at baseline in the apical and adjacent walls that was incongruous to the wall-motion abnormality. The perfusion defect improved within 72 hours on a repeated study indicating that microvasculature disruption is a key feature of this enigmatic cardiomyopathy.

Comparative costs of home positive inotropic infusion versus in-hospital care in patients awaiting cardiac transplantation.

BACKGROUND: Outpatient positive inotropic support combined with implantation of an automatic implantable cardioverter defibrillator (AICD) may be used as a successful bridge to cardiac transplantation in patients with end-stage heart failure. A detailed comparative cost analysis of this outpatient strategy versus in-hospital care has not been previously reported. METHODS AND RESULTS: Twenty-one United Network for Organ Sharing 1B patients awaiting cardiac transplantation received continuous outpatient inotropic therapy for a total of 3070 patient-days. Daily costs for outpatient and in-hospital treatment were calculated. Nonparametric decision analysis was used to determine the strategy with greatest cost savings (immediate hospital discharge after AICD implantation versus in-hospital care). A threshold analysis was performed to test the robustness of the decision analysis model. The outpatient strategy realized an average savings of $71,300 to $120,500 per patient. Decision analysis showed that no fixed period of in-hospital monitoring was more cost-saving than immediate hospital discharge after AICD implantation. Threshold analysis revealed that AICD costs would need to exceed $82,000 (currently $62,000) or that the difference between the outpatient and the in-hospital costs would need to be < or = $475 per day for any other intermediate strategy to be considered cost-saving. CONCLUSION: Outpatient inotropic therapy combined with AICD implantation in selected patients awaiting cardiac transplantation is an effective cost-minimizing strategy.

Identifying patients with degenerative mitral regurgitation for mitral valve repair and replacement: a transesophageal echocardiographic study.

OBJECTIVE: We sought to preoperatively identify the suitability of patients with degenerative mitral valve (MV) regurgitation for MV repair (MVR) and MV replacement. BACKGROUND: MVR is the preferred method of treatment over MV replacement, if surgically feasible. MVR preserves left ventricular function and decreases risk of hemolysis, thromboembolism, and-in the absence of anticoagulation-hemorrhage. However, the ability to identify patients suitable for MVR preoperatively is somewhat limited. METHODS: In all, 76 patients underwent MV operation for severe symptomatic mitral regurgitation. The decision to operate was at the discretion of the referring physician in consultation with respective cardiothoracic surgeons at two separate, nonrelated institutions. All patients underwent preoperative and/or intraoperative transesophageal echocardiographic studies. RESULTS: In all, 35 patients (46%) underwent MVR and 41 (54%) underwent MV replacement. There was no difference in the percentage of MVRs between the two institutions: 17 cases (41%) at Hahnemann University Hospital, Philadelphia, Pa, versus 18 cases (53%) at Northwestern University Memorial Hospital, Chicago, Ill (P = not significant). Age was found to be a significant univariate predictor with older age favoring MV replacement. On average, patients who underwent MVR were 11 years younger then those who underwent MV replacement. Heart failure was also found to be a significant univariate predictor: as New York Heart Association functional class worsened, MV replacement was more likely. Echocardiographic variables favoring MVR included chordal length (>29 mm, P <.001), length of posterior mitral leaflet (>17 mm, P <.008), and length of anterior leaflet (>25 mm, P <.01). The only echocardiographic parameter favoring replacement was the presence of anterior mitral annular calcification. Using multivariate analysis, older age (>63 years) was again a significant predictor favoring MV replacement (P <.002; odds ratio [OR] 20). Longer chordal length (>29 mm) was the strongest predictor favoring MVR (P <.001; OR 11.2). Longer length of the posterior leaflet (>17 mm; OR 5.07) and mitral annulus size > 35 mm (OR 7.75) were also significant multivariate predictors favoring MVR. The presence of anterior mitral annular calcification favored MV replacement using multivariate analysis (OR 25). CONCLUSIONS: Patients suitable for MVR can be identified preoperatively using a combination of clinical and echocardiographic parameters.

Home continuous positive inotropic infusion as a bridge to cardiac transplantation in patients with end-stage heart failure.

BACKGROUND: The clinical use of positive inotropic therapy at home in patients awaiting cardiac transplantation has not been reported since United Network for Organ Sharing (UNOS) regulations were changed to allow home infusions in Status 1B patients. METHODS: We observed 21 consecutive patients with UNOS 1B status during positive inotropic therapy at home. We used hemodynamic monitoring at the initiation of therapy to optimize dosing. We selected for home therapy patients with stable clinical status and improved functional capacity during inotropic treatment. Implantable cardioverter defibrillators were placed in all but 1 patient before discharge. RESULTS: Initial positive inotropic therapy included dobutamine in 12 patients (mean dose, 4.5 mcg/kg/min; range, 2.5-7.5 mcg/kg/min), milrinone in 8 patients (mean dose, 0.44 mcg/kg/min; range, 0.375-0.55 mcg/kg/min), and dopamine at a dose of 3 mcg/kg/min in 1 patient. Patients had improved functional capacity (New York Heart Association Class 3.7 +/- 0.1 to 2.4 +/- 0.2, p < 0.01), improved renal function (serum creatinine, 1.5 +/- 0.1 to 1.3 +/- 0.1, p < 0.01), improved resting hemodynamics, and decreased number of hospitalizations during positive inotropic infusion therapy when compared with pre-treatment baseline. Implantable cardioverter defibrillator discharges were infrequent (0.19 per 100 patient days of follow-up). Actuarial survival to transplantation at 6 and 12 months was 84%. CONCLUSIONS: Continuous positive inotropic therapy at home was safe and was associated with decreased health care costs in selected patients awaiting cardiac transplantation.