Massive expansion and cryopreservation of functional human induced pluripotent stem cell-derived cardiomyocytes

Since the discovery of human induced pluripotent stem cells (hiPSCs), numerous strategies have been established to efficiently derive cardiomyocytes from hiPSCs (hiPSC-CMs). Here, we describe a cost-effective strategy for the subsequent massive expansion (>250-fold) of high-purity hiPSC-CMs relying on two aspects: removal of cell-cell contacts and small-molecule inhibition with CHIR99021. The protocol maintains CM functionality, allows cryopreservation, and the cells can be used in downstream assays such as disease modeling, drug and toxicity screening, and cell therapy. For complete details on the use and execution of this protocol, please refer to Buikema (2020)

The circadian clock remains intact, but with dampened hormonal output in heart failure

Background: Circadian (24-h) rhythms are important regulators in physiology and disease, but systemic disease may disrupt circadian rhythmicity. Heart failure (HF) is a systemic disease affecting hormonal regulation. We investigate whether HF affects the rhythmic expression of melatonin and cortisol, main endocrine products of the central clock, and cardiac-specific troponin in patients. We corroborate the functionality of the peripheral clock directly in the organs of translational models, inaccessible in human participants. Methods: We included 46 HF patients (71.7% male, median age of 60 years, NYHA class II (32.6%) or III (67.4%), ischemic cardiomyopathy (43.5%), comorbidities: diabetes 21.7%, atrial fibrillation 30.4%), and 24 matched controls. Blood was collected at seven time-points during a 24-h period (totalling 320 HF and 167 control samples) for melatonin, cortisol, and cardiac troponin T (cTnT) measurements after which circadian rhythms were assessed through cosinor analyses, both on the individual and the group level. Next, we analysed peripheral circadian clock functionality using cosinor analysis in male animal HF models: nocturnal mice and diurnal zebrafish, based on expression of core clock genes in heart, kidneys, and liver, every 4 h during a 24-h period in a light/darkness synchronised environment. Findings: Melatonin and cortisol concentrations followed a physiological 24-h pattern in both patients and controls. For melatonin, acrophase occurred during the night for both groups, with significantly decreased amplitude (median 5.2 vs 8.8, P = 0.0001) and circadian variation ([maximum]/[minimum]) in heart failure patients. For cortisol, mesor showed a significant increase for HF patients (mean 331.9 vs 275.1, P = 0.017) with a difference of 56.8 (95% CI 10.3–103.3) again resulting in a relatively lower variation: median 3.9 vs 6.3 (P = 0.0058). A nocturnal blood pressure dip was absent in 77.8% of HF patients. Clock gene expression profiles (Bmal, Clock, Per, Cry) were similar and with expected phase relations in animal HF models and controls, demonstrating preserved peripheral clock functionality in HF. Furthermore, oscillations in diurnal zebrafish were expectedly in opposite phases to those of nocturnal mice. Concordantly, cTnT concentrations in HF patients revealed significant circadian oscillations. Interpretation: Central clock output is dampened in HF patients while the molecular peripheral clock, as confirmed in animal models, remains intact. This emphasises the importance of taking timing into account in research and therapy for HF, setting the stage for another dimension of diagnostic, prognostic and therapeutic approaches. Funding: Hartstichting

Feasibility of Linear Irreversible Electroporation Ablation in the Coronary Sinus

Introduction: Previous studies demonstrated that the coronary sinus (CS) is an important target for ablation in persistent atrial fibrillation. However, radiofrequency ablation in the CS is associated with coronary vessel damage and tamponade. Animal data suggest irreversible electroporation (IRE) ablation can be a safe ablation modality in vicinity of coronary arteries. We investigated the feasibility of IRE in the CS in a porcine model. Methods: Ablation and pacing was performed in the CS in six pigs (weight 60–75 kg) using a modified 9-French steerable linear hexapolar Tip-Versatile Ablation Catheter. Pacing maneuvers were performed from distal to proximal segments of the CS to assess atrial capture thresholds before and after IRE application. IRE ablations were performed with 100 J IRE pulses. After 3-week survival animals were euthanized and histological sections from the CS were analyzed. Results: A total of 27 IRE applications in six animals were performed. Mean peak voltage was 1509 ± 36 V, with a mean peak current of 22.9 ± 1.0 A. No complications occurred during procedure and 3-week survival. At 30 min post ablation 100% isolation was achieved in all animals. At 3 weeks follow-up pacing thresholds were significant higher as compared to baseline. Histological analysis showed transmural ablation lesions in muscular sleeves surrounding the CS. Conclusion: IRE ablation of the musculature along the CS using a multi-electrode catheter is feasible in a porcine model

3D MR coronary angiography: Optimization of the technique and preliminary results

Objective: Current clinical full MR angiography with multiple breathhold multiple thin slab acquisition (MTS) is difficult and arduous. This study describes the optimisation of the whole heart free - breathing balanced turbo field echo (B-TFE) protocol. A high-resolution image of the whole heart is produced in less or comparable time to MTS acquisition and allows for reconstruction afterwards to visualise the individual coronary arteries. The scan is easily performed because the volume has to be targeted only once. Design and setting: Eighteen healthy adults without a history of cardiovascular disease underwent free-breathing 3D MR angiography with the B-TFE protocol. The whole-heart data set was reformatted in identical orientations in all subjects to visualise the major coronary arteries. Main outcome measures: Vessel length, signal and contrast to noise ratio were determined and compared for each vessel. Results: Mean visible vessel lengths were 116 mm for the right, 102 mm for the left main and left descending and 76 mm for the left circumflex coronary artery. The average signal to noise ratio was 7.5 and contrast to noise ratio was 4.9. Because of the need for synchronised cardiac and respiratory triggering the coronaries could not be judged in 25% of the subjects. Conclusions: The optimised B-TFE protocol had equal judgeability and vessels could be judged over longer contiguous distances compared to earlier implementations of the B-TFE protocol. We conclude whole heart free breathing navigator-gated and slice-tracked 3D coronary MR angiography with use of the adjusted B-TFE protocol is possible, but still suboptimal for clinical use

The concept of triple wavefront fusion during biventricular pacing : Using the EGM to produce the best acute hemodynamic improvement in CRT

Background: Previous reports suggest that biventricular pacing (BiVp) fused with intrinsic conduction (BiVp-fusion, triple wavefront fusion) is associated with improved resynchronization compared to pure-BiVp in cardiac resynchronization therapy (CRT). This study aimed to assess the association between acute hemodynamic benefit of CRT and signs of BiVp-fusion by using a novel electrogram (EGM)-based method. Methods: In 17 patients undergoing CRT implantation, 28 combinations of atrioventricular (AV) and interventricular (VV) delays were applied while invasively measuring acute hemodynamic response based on maximum rate of left ventricular (LV) pressure rise (LV dP/dtmax) to assess optimal BiVp settings. BiVp-fusion was noted if farfield signal (caused by first intrinsic ventricular depolarization) was seen prior to right ventricular (RV) pacing (RVp) artifact on integrated bipolar RV EGM, or QRS morphology changed compared to pure-BiVp (short AV-delay) as seen on electrocardiogram (ECG). Results: Mean optimal RVp timing was at 98 ± 17% of intrinsic right atrial (RA)-RVfarfield (interval from right atrial pace or sense to RV farfield signal) interval, while preactivating the LV at 50 ± 11% of RA-RVsense (interval from right atrial pace or sense to RV sense interval) interval. BiVp-fusion was noted in 16 of 17 (94%) patients on ECG during optimal BiVp. Eight of these patients showed intrinsic farfield signal prior to RVp artifact on RV EGM. In the remaining eight, the RVp was paced just within the RA-RVfarfield interval with a mean of 25 ± 14 ms prior to the onset; therefore, the intrinsic farfield was masked. Conclusion: Optimal hemodynamic BiVp facilitates triple wavefront fusion, by pacing the RV around the onset of intrinsic farfield signal on RV EGM, while preactivating the LV. Aiming at BiVp-fusion could be a target for noninvasive EGM-based CRT device setting optimization

Sudden Death Due to Coronary Artery Lesions Long-term After the Arterial Switch Operation: A Systematic Review.

Background The arterial switch operation (ASO) is the preferred procedure for children with dextrotransposition of the great arteries or Taussig-Bing anomaly. Short- as well as long-term outcome of ASO are excellent, but coronary artery stenoses are reported as a common long-term complication. It has been hypothesized that these might result in sudden cardiac death late after ASO. Methods A systematic search of PubMed and EMBASE was conducted to evaluate sudden cardiac death because of coronary complications late after ASO. Data on patients surviving ≥ 5 years post-ASO were collected from selected studies, corrected for duplicate data, and analyzed. Results After duplicate data correction 52 studies remained for data analysis. Among the 8798 survivors with follow-up, 27 patients died ≥ 5 years post-ASO (0.3%). Of these patients, 10 were known with relevant residual lesions. Five late deaths were sudden, possibly from a cardiac cause. None of the late sudden deaths were confirmed to be coronary-related. Conclusions Sudden cardiac death in asymptomatic patients as a result of coronary artery stenosis or occlusion is extremely rare, with 5 possible cases and no proven cases of coronary artery-related sudden cardiac death in 8798 patients with 66,450 patient follow-up years. Therefore, routine coronary imaging of asymptomatic, single-stage ASO patients is not justified

Postoperative Delirium in Individuals Undergoing Transcatheter Aortic Valve Replacement : A Systematic Review and Meta-Analysis

Objectives: To evaluate the incidence of in-hospital postoperative delirium (IHPOD) after transcatheter aortic valve replacement (TAVR). Design: Systematic review and meta-analysis. Setting: Elective procedures. Participants: Individuals undergoing TAVR. Measurements: A literature search was conducted in PubMed, Embase, BioMedCentral, Google Scholar, and the Cochrane Central Register of Controlled Trials (up to December 2017). All observational studies reporting the incidence of IHPOD after TAVR (sample size > 25) were included in our meta-analysis. The reported incidence rates were weighted to obtain a pooled estimate rate with 95% confidence interval (CI). Results: Of 96 potentially relevant articles, 31 with a total of 32,389 individuals who underwent TAVR were included in the meta-analysis. The crude incidence of IHPOD after TAVR ranged from 0% to 44.6% in included studies, with a pooled estimate rate of 8.1% (95% CI=6.7–9.4%); heterogeneity was high (Q = 449; I = 93%; p heterogeneity <.001). The pooled estimate rate of IHPOD was 7.2% (95% CI=5.4–9.1%) after transfemoral (TF) TAVR and 21.4% (95% CI=10.3–32.5%) after non-TF TAVR. Conclusion: Delirium occurs frequently after TAVR and is more common after non-TF than TF procedures. Recommendations are made with the aim of standardizing future research to reduce heterogeneity between studies on this important healthcare problem. J Am Geriatr Soc 66:2417–2424, 2018