Assessment of left ventricular mechanical dyssynchrony by phase analysis of ECG-gated SPECT myocardial perfusion imaging

Cardiac resynchronization therapy (CRT) has shown benefits in patients with severe heart failure. However, at least 30% of patients selected for CRT by use of traditional criteria (New York Heart Association class III or IV, depressed left ventricular [LV] ejection fraction, and prolonged QRS duration) do not respond to CRT. Recent studies with tissue Doppler imaging have shown that the presence of LV dyssynchrony is an important predictor of response to CRT. Phase analysis has been developed to allow assessment of LV dyssynchrony by gated single photon emission computed tomography myocardial perfusion imaging. This technique uses Fourier harmonic functions to approximate regional wall thickness changes over the cardiac cycle and to calculate the regional onset-of-mechanical contraction phase. Once the onset-of-mechanical contraction phases are obtained 3-dimensionally over the left ventricle, a phase distribution map is formed that represents the degree of LV dyssynchrony. This technique has been compared with other methods of measuring LV dyssynchrony and shown promising results in clinical evaluations. In this review the phase analysis methodology is described, and its up-to-date validations are summarized.     

Topical treatments of laparoscopic port sites can decrease the incidence of incision metastasis

BACKGROUND: Anecdotal reports of port site tumor recurrence have dampened the enthusiasm for laparoscopic colectomy for cancer. We developed a rat model that creates a high incidence of port site metastasis following laparoscopic intervention. Our goal was to assess the feasibility of minimizing implantations using port site irrigation prior to wound closure. METHODS: Colon cancer carcinomatosis was established in 46 female BD9 rats using intraperitoneal injections of 10(6) DHD-K12-TRb rat colon cancer cells. This preparation yielded an 81% incidence of port site metastasis in a control group. Laparoscopic sham surgery was performed using four ports and a CO(2) pneumoperitoneum. Four treatment groups were studied by irrigating each port site as follows: Group I, sterile water; group II, normal saline; group III, heparin; group IV, 5-fluorouracil (5-FU). The animals were killed at 4 weeks, and the port sites were examined for tumors. RESULTS: There were no differences in port site metastasis between controls and groups I, II, and III. The 5-FU group showed a significant decrease (30% vs 81%) in metastasis. CONCLUSIONS: Port site irrigation with 5-FU at the time of laparoscopy reduces the incidence of port site tumor implantation in a rat colon cancer model. This finding may have utility in patients at high risk of such metastasis who undergo laparoscopy for colon cancer.     

Feasibility of assessment of coronary stent patency using 16-slice computed tomography

Intracoronary stent implantation is a frequently performed procedure in the treatment of stenoses in coronary arteries, but in-stent restenosis occurs in approximately 10% to 15% of patients. A noninvasive diagnostic procedure to evaluate in-stent restenosis would therefore be of great benefit. We investigated the feasibility of assessing stent patency with 16-slice computed tomography. Multislice computed tomography (MSCT) was performed in 22 patients with previously implanted stents. For each stent, assessability was determined and related to stent type and diameter. Subsequently, the presence of significant restenosis was determined in the evaluable stents. In addition, peristent lumina (5 mm proximal and distal to the stent) were evaluated. Conventional angiography in combination with quantitative coronary angiography served as the standard of reference. MSCT was performed successfully in all but 1 patient. Of 65 stents, 50 (77%) were determined assessable. Uninterpretable stents tended to have a thicker strut and/or a smaller diameter. In the evaluable stents, 7 of 9 stenoses were detected and the absence of restenosis was correctly identified in all 41 patent stents, resulting in a sensitivity and specificity of 78% and 100%, respectively. Sensitivity and specificity for the detection of peristent stenosis were 75% and 96%, respectively. In conclusion, MSCT may be useful in the assessment of stent patency and may function as a gatekeeper before invasive diagnostic procedures.     

Benefit of combined resynchronization and defibrillator therapy in heart failure patients with and without ventricular arrhythmias.

OBJECTIVES: We attempted to assess the efficacy of combined cardiac resynchronization therapy-implantable cardioverter-defibrillator (CRT-ICD) in heart failure patients with and without ventricular arrhythmias. BACKGROUND: Because CRT and ICDs both lower all-cause mortality in patients with advanced heart failure, combination of both therapies in a single device is challenging. METHODS: A total of 191 consecutive patients with advanced heart failure, left ventricular ejection fraction <35%, and a QRS duration >120 ms received CRT-ICD. Seventy-one patients had a history of ventricular arrhythmias (secondary prevention); 120 patients did not have prior ventricular arrhythmias (primary prevention). During follow-up, ICD therapy rate, clinical improvement after 6 months, and mortality rate were evaluated. RESULTS: During follow-up (18 +/- 4 months), primary prevention patients experienced less appropriate ICD therapies than secondary prevention patients (21% vs. 35%, p < 0.05). Multivariate analysis revealed, however, no predictors of ICD therapy. Furthermore, a similar, significant, improvement in clinical parameters was observed at 6 months in both groups. Also, the mortality rate in the primary prevention group was lower than in the secondary prevention group (3% vs. 18%, p < 0.05). CONCLUSIONS: As 21% of the primary prevention patients and 35% of the secondary prevention patients experienced appropriate ICD therapy within 2 years after implant, and no predictors of ICD therapy could be identified, implantation of a CRT-ICD device should be considered in all patients eligible for CRT.     

Assessment of myocardial viability by nuclear imaging techniques

The assessment of myocardial viability has become important in the diagnostic and prognostic work up of patients with ischemic cardiomyopathy. Patients with viable myocardium may benefit from revascularization in terms of improvement of function, symptoms, and prognosis. In contrast, patients without viable myocardium do not benefit and should be treated conservatively. Various nuclear imaging techniques are available.     

Prediction of improvement of ventricular function after revascularization: 18F-fluorodeoxyglucose single-photon emission computed tomography vs low-dose dobutamine echocardiography

AIMS: To compare assessment of myocardial flow and glucose metabolismby single-photon emission computed tomography (SPECT) with low-dosedobutamine echocardiography in predicting improvement in regionaland global left ventricular function after coronary artery bypassgrafting. METHODS AND RESULTS: Thirty patients with regional wall motion abnormalities (meanejection fraction 32±19%) were studied with low-dosedobutamine echocardiography (5 and 10 µg . kg^–1.min^–1) and thallium-201/ ¹⁸F-fluorodeoxyglucose(FDG) SPECTprior to surgery. For comparative analysis, a 13-segment modelwas used. Postoperative improvement was predicted if the echocardiogramshowed that wall motion abnormalities were reversible duringthe dobutamine infusion and there was normal perfusion or relativelyincreased FDG uptake in perfusion defects (mismatch) in dyssynergicsegments on SPECT. After surgery, ventricular function was reassessed.An echocardiogram was taken at the 3 month follow-up with thepatient at rest. Regional wall motion had improved in 62/168(37%) revascularized segments. In predicting functional outcome,low-dose dobutamine echocardiography reached a sensitivity of89% and a specificity of 82%, with a positive predictive valueof 74% and a negative predictive value of 93%, whereas for thallium-201/FDGSPECT these values were 84%, 86%, 78% and 90%, respectively.In patients with more than two viable segments on either technique,the wall motion score index, a surrogate of global ventricularfunction, improved significantly. CONCLUSION: For the optimal prediction of functional out-come, combinedassessment of flow and FDG imaging is needed. Both thallium-201/FDGSPECT and low-dose dobutamine echocardiography appear comparableand similarly accurate in predicting improvement of left ventricularfunction after surgical revascularization.     

In-stent fractional flow reserve variations and related optical coherence tomography findings: the FFR–OCT co-registration study

We sought to assess in-stent variations in fractional flow reserve (FFR) in patients with previous percutaneous coronary intervention (PCI) and to associate any drop in FFR with findings by optical coherence tomography (OCT) imaging. Suboptimal post-PCI FFR values were previously associated with poor outcomes. It is not known to which extent in-stent pressure loss contributes to reduced FFR. In this single-arm observational study, 26 patients who previously underwent PCI with drug-eluting stent or scaffold implantation were enrolled. Motorized FFR pullback during continuous intravenous adenosine infusion and OCT assessments was performed. Post-PCI FFR?<?0.94 was defined as suboptimal. At a median of 63 days after PCI (interquartile range: 59–64 days), 18 out of 26 patients (72%) had suboptimal FFR. The in-stent drop in FFR was significantly higher in patients with suboptimal FFR vs. patients with optimal FFR (0.08?±?0.07 vs. 0.01?±?0.02, p?<?0.001). Receiver operating characteristic curve analysis showed that an in-stent FFR variation of >?0.03 was associated with suboptimal FFR. In patients with suboptimal FFR, the OCT analyses revealed higher mean neointimal area (respectively: 1.06?±?0.80 vs. 0.51?±?0.23 mm²; p?=?0.018) and higher neointimal thickness of covered struts (respectively 0.11?±?0.07 vs. 0.06?±?0.01 mm; p?=?0.021). Suboptimal FFR values following stent-implantation are mainly caused by significant in-stent pressure loss during hyperemia. This finding is associated to a larger neointimal proliferation.