Percutaneous transluminal septal myocardial ablation markedly reduces energy loss in hypertrophic obstructive cardiomyopathy: a four-dimensional flow magnetic resonance imaging study

Background

Functional follow-up modalities of hypertrophic obstructive cardiomyopathy (HOCM) subjected to percutaneous transluminal septal myocardial ablation (PTSMA) are limited mainly to echocardiography and catheterization. Recent advancements in four-dimensional (4D) flow magnetic resonance imaging (MRI) have enabled us to assess patients from the perspective of fluid dynamics by visualising blood flow and calculating quantitative parameters such as wall shear stress and energy loss within cardiac chambers or blood vessels. Several reports have demonstrated that the intra-cardiac energy loss decreased along with improvement of cardiac function achieved by treatment of cardiac diseases. Whether changes in energy loss occur along with PTSMA in HOCM patients and the underlying mechanism remain unknown.

Purpose

This study sought to investigate the influence of PTSMA in patients with HOCM on energy loss in the left ventricle (LV) and aortic root measured by 4D flow MRI.

Methods

We retrospectively recruited HOCM patients who underwent PTSMA at a referral centre from May to November 2019. Patients who underwent 4D flow MRI both before and after PTSMA were included. We collected demographic and clinical data from electronic health records. MRI scans implemented two-dimensional phase-contrast imaging of the three-chamber plane with three-directional velocity, using a 1.5 T scanner. Furthermore, 4D blood flow analysis was performed on off-line saved data, using iTFlow version 1.9. We assessed energy loss in one cardiac cycle within the three-chamber plane of the LV and aortic root (area surrounded by the LV endocardium, sinotubular junction, and mitral annulus).

Results

This study finally included 12 patients, whose mean age was 66±12 years, and 5 (42%) of whom were men. The pressure gradient between the LV apex and ascending aorta was 81±32 mmHg before and 20±22 mmHg immediately after PTSMA (P<0.005, paired). Before PTSMA, 6 patients were in New York Heart Association functional class III and the other 6 in class II. However, after PTSMA, 10 patients improved to class I and 2 to class II. PTSMA reduced energy loss in one cardiac cycle within the three-chamber plane of the LV and aortic root, from 79±36 mJ/m to 55±19 mJ/m (P=0.001, paired).

Conclusions

PTSMA in patients with HOCM reduced energy loss within the LV and aortic root, indicating significant decrease with cardiac workload. Four-dimensional flow MRI of the three-chamber plane to assess energy loss within the LV and aortic root is a time-efficient and reproducible quantitative method to evaluate the effects of PTSMA. Given its non-invasive nature, it also enables to sequentially follow-up HOCM patients who underwent PTSMA.

Periprocedural changes of energy loss

Funding Acknowledgement

Type of funding source: None

The effect of underweight on mid-term outcome following transcatheter aortic valve implantation: an insight from multicenter registry

Background

Obesity has the adverse prognostic impact in the general population, whereas paradoxical effect of obesity has been reported in patients with heart failure. Several studies have suggested the same obesity paradox in patients undergoing transcatheter aortic valve implantation (TAVI), however, they included limited number of underweight patients.

Purpose

The aim of this study was to clarify the effect of underweight on outcome following TAVI.

Methods

We retrospectively analyzed consecutive 1,027 patients undergoing TAVI between April 2010 and June 2019. The patients were categorized according to body mass index (BMI) as follows: underweight (<18.5 kg/m2, n=150), normal weight (18.5 to 25 kg/m2, n=657), and overweight (>25 kg/m2, n=220). BMI was defined as body weight (kg) divided by the square of body height (m) measured at the hospital admission. We compared the short- and mid-term outcome after TAVI among three groups, and all clinical events were accordance with Valve Academic Research Consortium-2 criteria.

Results

Underweight patients were more often female, and had a higher prevalence of hypertension, dyslipidemia, peripheral artery disease, anemia, and hypoalbuminemia. They also presented lower ejection fraction, smaller aortic valve area, and higher surgical risk score. In procedural findings, device unsuccess and major vascular complication more occurred in underweight patients, but 30-day mortality was equivalent among three groups. The mid-term survival of the underweight was inferior to the other two groups (figure).In the multivariate analysis, female (hazard ratio [HR] 0.52, 95% confidence interval [CI] 0.37–0.73, P=0.0002), atrial fibrillation (HR 2.22, 95% CI 1.56–3.17, P<0.0001), albumin value (HR 0.37 per 1-g/dl increase, 95% CI 0.25–0.55, P<0.0001), Society of Thoracic Surgeons score (HR 1.06 per 1% increase, 95% CI 1.02–1.06, P=0.0039), 30-day combined endpoint (HR 2.12, 95% CI 1.33–3.38, P=0.0017), and underweight (HR 1.59, 95% CI 1.04–2.37, P=0.026) were associated with the survival after TAVI.

Conclusion

The underweight had a worse mid-term prognosis, representing the obesity paradox in the TAVI population.

Kaplan-Meier curves

Funding Acknowledgement

Type of funding source: None

Polyion complex micelles as vectors in gene therapy--pharmacokinetics and in vivo gene transfer

To establish non-viral gene delivery systems for intravenous administration, complexes of DNA and block copolymer consisting of poly-L-lysine and poly(ethylene glycol) were tested in in vivo turnover studies. The polyion complex micelles have self-assembling core-shell structures, yielding spherical nano-particles with small absolute values of zeta-potential. Southern blot analysis showed that supercoiled DNA was observed for 30 min and open circular or linear DNA was seen for 3 h after intravenous administration of PIC micelles having the charge ratios of 1:4 and PLL length of 48 mer. The PIC micelles with shorter PLL length showed lower stability in the blood stream suggesting that DNA is able to persist as an intact molecule in the blood stream using this system. Though having no ligands, PIC micelles with charge ratios of 1:2 and 1:4 transfected efficiently into HepG2 cells. Preincubation with free copolymer inhibited expression of the reporter gene, suggesting that adsorption of block copolymer to the cell surface blocked the interaction site of the PIC micelles. When the PIC micelles were injected via supramesenteric vein, expression of the gene was observed only in the liver and was sustained for 3 days. It was suggested that this gene delivery system is intrinsically efficient.

Comparative study of the sugar chains of gamma-glutamyltranspeptidases purified from human hepatocellular carcinoma and from human liver

The sugar chains of gamma-glutamyltranspeptidases, purified from human hepatoma and from normal human liver, were released quantitatively as oligosaccharides by hydrazinolysis. Comparative study of their structures revealed that the following structural alterations are induced by hepatocyte carcinogenesis: 1) high mannose type sugar chains are detected in the hepatoma enzyme but not in the normal liver enzyme; 2) abnormal biantennary sugar chains containing C-2,4 outer chain branches newly appeared; 3) the total amounts of tri- and tetraantennary sugar chains containing C-2,6 outer chain branches increased up to three times.

Comparison of drug-metabolizing activities in the livers of carcinogen-sensitive parent rats and carcinogen-resistant descendants

Donryu strain albino rats were maintained on a diet containing 0.06% 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) for nine successive generations. Some rats in the fourth to eighth generations showed marked resistance to the carcinogenic action of 3'-Me-DAB. In the liver where we found tumors, their size and number are smaller than in the corresponding original strain of rats fed on a diet containing 3'-Me-DAB. No significant differences were found in the total cytochrome P-450 contents or epoxide hydrolase activities of the livers of the resistant variant and the original strain, but the benzo(a)pyrene hydroxylase activity which is mainly attributed to cytochrome P-448 and glutathione S-transferase activity of the resistant variant were lower. The inductions of hepatic cytochrome P-488 and benzo(a)pyrene hydroxylase on administration of polychlorinated biphenyls or 3-methylcholanthrene were also lower in the resistant rats. In the mutagenicity test on Salmonella typhimurium TA 98 the liver 9000 X g supernatant fraction from 3'-Me-DAB-resistant F7 rats did not fully induce the mutagenicities of 3'-Me-DAB and several other carcinogens. Thus the resistance of F7 rats to the chemical carcinogen may be related to the lower activities of some drug-metabolizing enzymes and the poor inducibility of cytochrome P-448 in their liver, although selection of resistant rats should be continued for further generations before coming to a definite conclusion on biochemical basis of apparent resistance to 3'-Me-DAB.