Minimally-invasive approaches have become increasingly important in cardiac valve surgery. Smaller incisions have become commonplace in many major centers. We reviewed the existing literature and present the current state-of-the-art of minimally-invasive valve operations in this paper.
OBJECTIVES: Recently, small calcifications have been associated with unstable plaques. Plaque calcifications are both in intravascular ultrasound (IVUS) and multi-slice computed tomography (MSCT) easily recognized. However, smaller calcifications might be missed on MSCT due to its lower resolution.
METHODS: Because it is unknown to which extent calcifications can be detected with MSCT, we compared calcification detection on contrast enhanced MSCT with IVUS. The coronary arteries of patients with myocardial infarction or unstable angina were imaged by 64-slice MSCT angiography and IVUS. The IVUS and MSCT images were registered and the arteries were inspected on the presence of calcifications on both modalities independently. We measured the length and the maximum circumferential angle of each calcification on IVUS.
RESULTS: In 31 arteries, we found 99 calcifications on IVUS, of which only 47 were also detected on MSCT. The calcifications missed on MSCT (n = 52) were significantly smaller in angle (27° ± 16° vs. 59° ± 31°) and length (1.4 ± 0.8 vs. 3.7 ± 2.2 mm) than those detected on MSCT. Calcifications could only be detected reliably on MSCT if they were larger than 2.1 mm in length or 36° in angle.
CONCLUSIONS: Half of the calcifications seen on the IVUS images cannot be detected on contrast enhanced 64-slice MSCT angiography images because of their size. The limited resolution of MSCT is the main reason for missing small calcifications.
PMID: 20602171
OBJECTIVES: The purpose of this study was to describe radiation exposure from cardiac imaging procedures over time in a general population. Cardiac imaging procedures frequently expose patients to ionizing radiation, but their contribution to effective doses of radiation in the general population is unknown.
METHODS: We used administrative claims to identify cardiac imaging procedures performed from 2005 to 2007 in 952,420 nonelderly insured adults in 5 U.S. health care markets. We estimated 3-year cumulative effective doses of radiation in millisieverts from these procedures We then calculated population-based annual rates of radiation exposure to effective doses 
3 mSv/year (background level ofradiation from natural sources), >3 to 20 mSv/year, or >20 mSv/year (upper annual limit for occupational exposure averaged over 5 years).
RESULTS: A total of 90,121 (9.5%) individuals underwent at least 1 cardiac imaging procedure using radiation. Among patients who underwent 
1 cardiac imaging procedures, the mean cumulative effective dose over 3 years was 16.4 mSv (range 1.5 to 189.5 mSv). Myocardial perfusion imaging accounted for 74% of the cumulative effective dose. Overall, 47.8% of cardiac imaging procedures were performed in physician offices; this proportion was higher for myocardial perfusion imaging (74.8%) and cardiac computed tomography studies (76.5%). The annual population-based rate of receiving an effective dose of >3 to 20 mSv/year was 89.0 per 1,000; and 3.3 per 1,000 for cumulative doses >20 mSv/year. Annual effective doses increased with age and were generally higher among men.
CONCLUSIONS: Cardiac imaging procedures lead to substantial radiation exposure and effective doses for many patients in the U.S.
OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is a new option for patients with severe aortic stenosis at high surgical risk. The standard retrograde approach through the femoral artery is contraindicated in case of unfavorable iliofemoral anatomy or extensive disease. In these patients, a trans-subclavian approach may be feasible.
METHODS: Between June 2007 and July 2009, TAVI with the CoreValve bioprosthesis (Medtronic, Minneapolis, Minn) was performed in 514 consecutive patients at 13 Italian hospitals, using the subclavian approach in 54 cases.
RESULTS: The median logistic EuroSCORE was significantly higher in the subclavian (19.4; interquartile range, 12.5 to 29.8) versus femoral group (25.3; interquartile range, 15.1 to 36.6) (P=0.03), as well as the rate of comorbidities. Procedural success was obtained in 100% versus 98.4% of the subclavian versus femoral groups, respectively (P=0.62), with intraprocedural mortality of 0% versus 0.9% (P=1.00). The most common in-hospital complications were a new left bundle-branch block (22.4%) and the need for pacemaker (16.3%). No specific complications for the subclavian access (vessel rupture, vertebral or internal mammary ischemia) were reported. The learning curve for the subclavian approach led to a wider use of local anesthesia. Thirty-day mortality was 0% versus 6.1% in the subclavian versus femoral groups, respectively (P=0.13). Six-month mortality rate was 9.4% versus 15.8% (P=0.44), whereas valve-related adverse events were 13.6% versus 13.9% (P=0.79). \
CONCLUSIONS: TAVI through the subclavian approach appeared feasible and safe, with excellent procedural success and low in-hospital complication rates. This new technique allows patients with contraindications to the femoral approach to be treated with TAVI.
PMID: 20606135
OBJECTIVES: We compared the annulus diameters measured by transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and dual-source computed tomography (DSCT) prior to transcatheter aortic valve implantation (TAVI). In TAVI correct evaluation of the aortic annulus is mandatory in order to choose the correct prosthesis type and size and to prevent complications. There is no gold standard for the assessment of aortic annulus diameters.
METHODS: Preoperative assessment of the aortic annulus with TTE, TEE and DSCT was performed in 187 consecutive patients referred for TAVI between 06/2007 and 05/2009.
RESULTS: The mean aortic annuli were 22.6+/-2.0mm measured with DSCT, 22.3+/-2.5mm with TTE and 22.9+/-2.2mm with TEE. Despite a strong correlation between the measurement techniques relevant statistical spread occurred with differences up to 3mm in all measurement methods. Inter- and intra-observer variability was good for TEE and less satisfactory for DSCT measurements. TEE measurements taken as decisive parameter for the implantation changed the implantation strategy in 15,5% of patients and did not show an increased rate of procedural complications.
CONCLUSION: Despite a strong correlation, the measurement techniques for the aortic annulus show relevant statistical spread, consequently one measurement technique cannot definitely predict another. TEE measurements show a more satisfactory intra- and inter-observer variability than DSCT. Taking TEE annulus measurements as decisive parameter for the implantation has an impact on the implantation strategy and is safe with a low rate of procedural complications.
PMID: 20518012
OBJECTIVES: The aim of this study was to investigate the relationship between intravascular ultrasound (IVUS)-derived measures of atherosclerosis and cardiovascular outcomes. IVUS has been used in clinical trials to evaluate the effect of medical therapies on coronary atheroma progression.
METHODS: Coronary plaque progression was evaluated in 4,137 patients in 6 clinical trials that used serial IVUS. The relationship between baseline and change in percent atheroma volume (PAV) and total atheroma volume with incident major adverse cardiovascular events (MACE) was investigated.
RESULTS: PAV increased by 0.3% (p < 0.001), and 19.9% of subjects experienced MACE (0.9% death, 1.8% myocardial infarction, 18.9% coronary revascularization). Greater baseline PAVs were observed in patients who experienced myocardial infarctions (42.2 +/- 9.6% vs. 38.6 +/- 9.1%, p = 0.001), coronary revascularization (41.2 +/- 9.3% vs. 38.1 +/- 9.0%, p < 0.001), or MACE (41.3 +/- 9.2% vs. 38.0 +/- 9.0%, p < 0.001). Each standard deviation increase in PAV was associated with a 1.32-fold (95% confidence interval: 1.22 to 1.42; p < 0.001) greater likelihood of experiencing a MACE. During follow-up (21.1 +/- 3.7 months), greater increases in PAV, but not total atheroma volume, were observed in subjects who experienced MACE compared with those who did not (0.95 +/- 0.19% vs. 0.46 +/- 0.16%, p < 0.001). Each standard deviation increase in PAV was associated with a 1.20-fold (95% confidence interval: 1.10 to 1.31; p < 0.001) greater risk for MACE. Multivariate analysis revealed that factors associated with MACE included baseline PAV (p < 0.0001), change in PAV (p = 0.002), smoking (p = 0.0002) and hypertension (p = 0.01).
CONCLUSIONS: A direct relationship was observed between the burden of coronary atherosclerosis, its progression, and adverse cardiovascular events. The relationship between disease progression and outcomes largely reflected the need for coronary revascularization. These data support the use of atherosclerosis imaging with IVUS in the evaluation of novel antiatherosclerotic therapies.
PMID: 20488313
OBJECTIVES: Intravascular ultrasound derived virtual histology (VH IVUS) is used increasingly in clinical research to assess composition and vulnerability of coronary atherosclerotic lesions. However, the ability of VH IVUS to quantify individual plaque components, in particular the size of the destabilizing necrotic core, has never been validated. We tested for correlation between VH IVUS necrotic core size and necrotic core size by histology in porcine coronary arteries with human-like coronary disease.
METHODS: In adult atherosclerosis-prone minipigs, 18 advanced coronary lesions were assessed by VH IVUS in vivo followed by postmortem microscopic examination (histology).
RESULTS: We found no correlation between the size of the necrotic core determined by VH IVUS and histology. VH IVUS displayed necrotic cores in lesions lacking cores by histology.
CONCLUSIONS: We found no correlation between necrotic core size determined by VH IVUS and real histology, questioning the ability of VH IVUS to detect rupture-prone plaques, so-called thin-cap fibroatheromas.
PMID: 20460496
OBJECTIVES: To summarize the results of all original cost-utility analyses (CUAs) in diagnostic cardiovascular imaging (CVI) and characterize those technologies by estimates of their cost-effectiveness.
METHODS: We systematically searched the literature for original CVI CUAs published between 2000 and 2008. Studies were classified according to several variables including anatomy of interest (e.g. cerebrovascular, aorta, peripheral) and imaging modality under study (e.g. angiography, ultrasound). The results of each study, expressed as cost of the intervention to number of quality-adjusted life years saved ratio (cost/QALY) were additionally classified as favorable or not using $20,000, $50,000, and $100,000 per QALY thresholds. The distribution of results was assessed with Chi Square or Fisher exact test, as indicated.
RESULTS: Sixty-nine percent of all cardiovascular imaging CUAs were published between 2000 and 2008. Thirty-two studies reporting 82 cost/QALY ratios were included in the final sample. The most common vascular areas studied were cerebrovascular (n = 9) and cardiac (n = 8). Sixty-six percent (21/32) of studies focused on sonography, followed by conventional angiography and CT (25%, n = 8, each). Twenty-nine (35.4%), 42 (51.2%), and 53 (64.6%) ratios were favorable at WTP $20,000/QALY, $50,000/QALY, and $100,000/QALY, respectively. Thirty (36.6%) ratios compared one imaging test versus medical or surgical interventions; 26 (31.7%) ratios compared imaging to a different imaging test and another 26 (31.7%) to no intervention. Imaging interventions were more likely (P < 0.01) to be favorable when compared to observation, medical treatment or non-intervention than when compared to a different imaging test at WTP $100,000/QALY.
CONCLUSIONS: The diagnostic cardiovascular imaging literature has growth substantially. The studies available have, in general, favorable cost-effectiveness profiles with major determinants relating to being compared against observation, medical or no intervention instead of other imaging tests.
PMID: 20446040
OBJECTIVES: We used virtual histology intravascular ultrasound (VH-IVUS) to investigate the natural history of coronary artery lesion morphology. Plaque stability is related to its histological composition.
METHODS: We performed serial (baseline and 12-month follow-up) VH-IVUS studies and examined 216 nonculprit lesions (plaque burden >40%) in 99 patients. Lesions were classified into pathological intimal thickening (PIT), VH-IVUS-derived thin-capped fibroatheroma (VH-TCFA), thick-capped fibroatheroma (ThCFA), fibrotic plaque, and fibrocalcific plaque.
RESULTS: At baseline, 20 lesions were VH-TCFAs; during follow-up, 15 (75%) VH-TCFAs “healed,” 13 became ThCFAs, 2 became fibrotic plaque, and 5 (25%) VH-TCFAs remained unchanged. Compared with VH-TCFAs that healed, VH-TCFAs that remained VH-TCFAs located more proximally (values are median [interquartile range]) (16 mm [15 to 18 mm] vs. 31 mm [22 to 47 mm], p = 0.013) and had larger lumen (9.1 mm(2) [8.2 to 10.7 mm(2)] vs. 6.9 mm(2) [6.0 to 8.2 mm(2)], p = 0.021), vessel (18.7 mm(2) [17.3 to 28.6 mm(2)] vs. 15.5 mm(2) [13.3 to 16.6 mm(2)]; p = 0.010), and plaque (9.7 mm(2) [9.6 to 15.7 mm(2)] vs. 8.4 mm(2) [7 to 9.7 mm(2)], p = 0.027) areas; however, baseline VH-IVUS plaque composition did not differ between VH-TCFAs that healed and VH-TCFAs that remained VH-TCFAs. Conversely, 12 new VH-TCFAs developed; 6 late-developing VH-TCFAs were PITs, and 6 were ThCFAs at baseline. In addition, plaque area at minimum lumen sites increased significantly in PITs (7.8 mm(2) [6.2 to 10.0 mm(2)] to 9.0 mm(2) [6.5 to 12.0 mm(2)], p < 0.001), VH-TCFAs (8.6 mm(2) [7.3 to 9.9 mm(2)] to 9.5 mm(2) [7.8 to 10.8 mm(2)], p = 0.024), and ThCFAs (8.6 mm(2) [6.8 to 10.2 mm(2)] to 8.8 mm(2) [7.1 to 11.4 mm(2)], p < 0.001) with a corresponding decrease lumen areas, but not in fibrous or fibrocalcific plaque.
CONCLUSIONS: Most VH-TCFAs healed during 12-month follow-up, whereas new VH-TCFAs also developed. PITs, VH-TCFAs, and ThCFAs showed significant plaque progression compared with fibrous and fibrocalcific plaque.
PMID: 20378076
OBJECTIVES: Identification of patients at risk for primary and secondary manifestations of atherosclerotic disease progression is based mainly on established risk factors. The atherosclerotic plaque composition is thought to be an important determinant of acute cardiovascular events, but no prospective studies have been performed. The objective of the present study was to investigate whether atherosclerotic plaque composition is associated with the occurrence of future vascular events.
METHODS: Atherosclerotic carotid lesions were collected from patients who underwent carotid endarterectomy and were subjected to histological examination. Patients underwent clinical follow-up yearly, up to 3 years after carotid endarterectomy. The primary outcome was defined as the composite of a vascular event (vascular death, nonfatal stroke, nonfatal myocardial infarction) and vascular intervention. The cumulative event rate at 1-, 2-, and 3-year follow-up was expressed by Kaplan–Meier estimates, and Cox proportional hazards regression analyses were performed to assess the independence of histological characteristics from general cardiovascular risk factors.
RESULTS: During a mean follow-up of 2.3 years, 196 of 818 patients (24%) reached the primary outcome. Patients whose excised carotid plaque revealed plaque hemorrhage or marked intraplaque vessel formation demonstrated an increased risk of primary outcome (risk difference=30.6% versus 17.2%; hazard ratio [HR] with [95% confidence interval]=1.7 [1.2 to 2.5]; and risk difference=30.0% versus 23.8%; HR=1.4 [1.1 to 1.9], respectively). Macrophage infiltration (HR=1.1 [0.8 to 1.5]), large lipid core (HR=1.1 [0.7 to 1.6]), calcifications (HR=1.1 [0.8 to 1.5]), collagen (HR=0.9 [0.7 to 1.3]), and smooth muscle cell infiltration (HR=1.3 [0.9 to 1.8]) were not associated with clinical outcome. Local plaque hemorrhage and increased intraplaque vessel formation were independently related to clinical outcome and were independent of clinical risk factors and medication use.
CONCLUSIONS: The local atherosclerotic plaque composition in patients undergoing carotid endarterectomy is an independent predictor of futurecardiovascular events.
OBJECTIVES: The majority of prosthetic heart valves currently implanted are tissue valves that can be expected to degenerate with time and eventually fail. Repeat cardiac surgery to replace these valves is associated with significant morbidity and mortality. Transcatheter heart valve implantation within a failed bioprosthesis, a “valve-in-valve” procedure, may offer a less invasive alternative.
METHODS: Valve-in-valve implantations were performed in 24 high-risk patients.
RESULTS: Failed valves were aortic (n=10), mitral (n=7), pulmonary (n=6), or tricuspid (n=1) bioprostheses. Implantation was successful with immediate restoration of satisfactory valve function in all but 1 patient. No patient had more than mild regurgitation after implantation. No patients died during the procedure. Thirty-day mortality was 4.2%. Mortality was related primarily to learning-curve issues early in this high-risk experience. At baseline, 88% of patients were in New York Heart Association functional class III or IV; at the last follow-up, 88% of patients were in class I or II. At a median follow-up of 135 days (interquartile range, 46 to 254 days) and a maximum follow-up of 1045 days, 91.7% of patients remained alive with satisfactory valve function.
CONCLUSIONS: Transcatheter valve-in-valve implantation is a reproducible option for the management of bioprosthetic valve failure. Aortic, pulmonary, mitral, and tricuspid tissue valves were amenable to this approach. This finding may have important implications with regard to valve replacement in high-risk patients.
OBJECTIVES: The aim of this study was prospective investigation of silent and clinically apparent cerebral embolic events and neurological impairment after transfemoral aortic valve implantation (TAVI). Transfemoral aortic valve implantation is a novel therapeutic approach for multimorbid patients with severe aortic stenosis. We investigated peri-interventional cerebral embolism with diffusion-weighted magnetic resonance imaging (DW-MRI) and its relationship to clinical and serologic parameters of brain injury.
METHODS: Cerebral DW-MRI was performed before, directly and 3 months after TAVI with the current third-generation self-expanding Corevalve (Medtronic, Minneapolis, Minnesota) prosthesis. At the timepoints of the serial MRI studies, focal neurological impairment was assessed according to the National Institutes of Health Stroke Scale (NIHSS), and serum concentration of neuron-specific enolase (NSE), a marker of the volume of brain tissue involved in an ischemic event, were determined.
RESULTS: Thirty patients were enrolled; 22 completed the imaging protocol. Three patients (10%) had new neurological findings after TAVI, of whom only 1 (3.6%) had a permanent neurological impairment. Of the 22 TAVI patients with complete imaging data, 16 (72.7%) had 75 new cerebral lesions after TAVI presumed to be embolic. The NIHSS and NSE were not correlated with DW-MRI lesions.
CONCLUSIONS: The incidence of clinically silent peri-interventional cerebral embolic lesions after TAVI is high. However, in this cohort of 30 patients, the incidence of persistent neurological impairment was low. (Incidence and Severity of Silent and Apparent Cerebral Embolism After Conventional and Minimal-invasive Transfemoral Aortic Valve Replacement; NCT00883285).
PMID: 20188503
OBJECTIVES: To evaluate the outcome of transapical aortic valve implantation (TA-AVI) in comparison to conventional surgery.
METHODS: One hundred consecutive high-risk patients with symptomatic aortic valve stenosis received TA-AVI using the Edwards SAPIEN™ pericardial xenograft between February 2006 and January 2008. Patient age was 82.7 ± 5 years, 77 were females, logistic EuroSCORE predicted risk of mortality was 29.4 ± 13% and Society Thoracic Surgeons score risk for mortality was 15.2 ± 8.3%. Propensity score analysis was used to identify a control group of patients that underwent conventional aortic valve replacement (C-AVR).
RESULTS: Transapical aortic valve implantation was performed successfully in 97 patients, whereas three patients required early conversion. There were no new onset neurological events in the TA-AVI group and early extubation was performed in 82 patients. Echocardiography revealed good valve function with low transvalvular gradients in all patients. Thirty-day survival was 90 ± 3 vs. 85 ± 4% for TA-AVI vs. C-AVR, and 1-year survival was 73 ± 4 vs. 69 ± 5% (P = 0.55).
CONCLUSIONS: Transapical aortic valve implantation is a safe, minimally invasive, and off-pump technique to treat high-risk patients with aortic stenosis. Results of the initial 100 patients are good and compare favourably to conventional surgery.
PMID: 20233788
OBJECTIVIES: There are few data on adding left atrial volume index (LAVi) or pulmonary artery systolic pressure (PAP) to the ratio of early mitral inflow to mitral annular velocity (E/e’) for the estimation of left ventricular (LV) filling pressure in patients with preserved LV ejection fractions (LVEFs) (>50%).
METHODS: Patients underwent echocardiography within 20 minutes of cardiac catheterization. Echocardiographic variables were compared with invasively measured LV preatrial contraction pressure (pre-A).
RESULTS: Of the 122 patients studied (mean age, 55 +/- 9 years; mean LVEF, 61 +/- 6%), 67 (55%) were women, 108 (88%) had hypertension, and 79 (65%) had significant coronary artery disease at catheterization. E/e’ was significantly correlated with pre-A (R = 0.63, P < .0001) compared with LAVi (R = 0.49, P < .001) and PAP (R = 0.48, P < .001). E/e’ > 13 had sensitivity of 70% and specificity of 93% (area under the curve [AUC], 0.82; P < .0001), LAVi > 31 mL/m2 had sensitivity of 78% and specificity of 76% (AUC, 0.80, P < .001), and PAP > 28 mm Hg had sensitivity of 80% and specificity of 64% for pre-A > 15 mm Hg (AUC, 0.77, P < .001). Adding LAVi >31 mL/m2 for E/e’ = 8 to 13 significantly increased the accuracy of E/e’ > 13 alone (sensitivity, 87%; specificity, 88%; AUC, 0.89; P = .01 for comparison). However, adding PAP > 28 mm Hg for E/e’ = 8 to 13 did not significantly increase the accuracy of E/e’ > 13 alone (AUC, 0.82; sensitivity, 82%; specificity, 72%; P = NS for comparison).
CONCLUSIONS: In patients with preserved LVEFs, adding LAVi > 31 mL/m2 to E/e’ (when E/e’ was in the gray zone, but not when E/e’ was >13) significantly increased the accuracy of E/e’ alone for the estimation of LV filling pressure. These data support the notion of using several, rather than any single, Doppler echocardiographic parameter for the accurate assessment of LV diastolic function.
PMID: 20152696
OBJECTIVES: We developed and tested a novel transcatheter circumferential annuloplasty technique to reduce mitral regurgitation in porcine ischemic cardiomyopathy. Catheter-based annuloplasty for secondary mitral regurgitation exploits the proximity of the coronary sinus to the mitral annulus, but is limited by anatomic variants and coronary artery entrapment.
METHODS: The procedure, “cerclage annuloplasty,” is guided by magnetic resonance imaging (MRI) roadmaps fused with live X-ray. A coronary sinus guidewire traverses a short segment of the basal septal myocardium to re-enter the right heart where it is exchanged for a suture. Tension is applied interactively during imaging and secured with a locking device.
RESULTS: We found 2 feasible suture pathways from the great cardiac vein across the interventricular septum to create cerclage. Right ventricular septal re-entry required shorter fluoroscopy times than right atrial re-entry, which entailed a longer intramyocardial traversal but did not cross the tricuspid valve. Graded tension progressively reduced septal-lateral annular diameter, but not end-systolic elastance or regional myocardial function. A simple arch-like device protected entrapped coronary arteries from compression even during supratherapeutic tension. Cerclage reduced mitral regurgitation fraction (from 22.8 +/- 12.7% to 7.2 +/- 4.4%, p = 0.04) by slice tracking velocity-encoded MRI. Flexible cerclage reduced annular size but preserved annular motion. Cerclage also displaced the posterior annulus toward the papillary muscles. Cerclage introduced reciprocal constraint to the left ventricular outflow tract and mitral annulus that enhanced leaflet coaptation. A sample of human coronary venograms and computed tomography angiograms suggested that most have suitable venous anatomy for cerclage.
CONCLUSIONS: Transcatheter mitral cerclage annuloplasty acutely reduces mitral regurgitation in porcine ischemic cardiomyopathy. Entrapped coronary arteries can be protected. MRI provided insight into the mechanism of cerclage action.
PMID: 19660696
