Profiling the Biomechanical Responses to Workload on the Human Myocyte to Explore the Concept of Myocardial Fatigue and Reversibility: Rationale and Design of the POWER Heart Failure Study

It remains unclear why some patients develop heart failure without evidence of structural damage. One theory relates to impaired myocardial energetics and ventricular-arterial decoupling as the heart works against adverse mechanical load. In this original study, we propose the novel concept of myocardial fatigue to capture this phenomenon and aim to investigate this using human cardiomyocytes subjected to a modern work-loop contractility model that closely mimics in vivo cardiac cycles. This proof-of-concept study (NCT04899635) will use human myocardial tissue samples from patients undergoing cardiac surgery to develop a reproducible protocol to isolate robust calcium-tolerant cardiomyocytes. Thereafter, work-loop contractility experiments will be performed over a range of preload, afterload and cycle frequency as a function of time to elicit any reversible reduction in contractile performance (i.e. fatigue). This will provide novel insight into mechanisms behind heart failure and myocardial recovery and serve as a valuable research platform in translational cardiovascular research.

Safety and feasibility of trans-venous cardiac device extraction using conscious sedation alone-Implications for the post-COVID-19 era

BACKGROUND

Transvenous lead extraction (TLE) for implantable cardiac-devices is traditionally performed under general anesthesia (GA). This can lead to greater risk of exposure to COVID-19, longer recovery-times and increased procedural-costs. We report the feasibility/safety of TLE using conscious-sedation alone with immediate GA/cardiac-surgery back-up if needed.

METHODS

Retrospective case-series of consecutive TLEs performed using conscious-sedation alone between March 2016 and December 2019. All were performed in the electrophysiology-laboratory using intravenous Fentanyl, Midazolam/Diazepam with a stepwise approach using locking-stylets/cutting-sheaths, including mechanical-sheaths. Baseline patient-characteristics, procedural-details and TLE outcomes (including procedure-related complications/death) were recorded.

RESULTS

A total of 130 leads were targeted in 54 patients, mean age ± SD 74.6 ± 11.8years, 47(87%) males; dual-chamber pacemakers (n = 26; 48%), cardiac resynchronization therapy-defibrillators (n = 17; 31%) and defibrillators (n = 8; 15%) were commonest extracted devices. Mean ± SD/median (range) lead-dwell times were 11.0 ± 8.8/8.3 (0.3-37) years, respectively. Extraction indications included systemic infection (n = 23; 43%) and lead/pulse-generator erosion (n = 27; 50%); mean 2.1 ± 2.0 leads were removed per procedure/mean procedure-time was 100 ± 54 min. Local anesthetic (LA) was used for all (mean-dose: 33 ± 8 ml 1% lidocaine), IV drug-doses used (mean ± SD) were: midazolam: 3.95 ± 2.44 mg, diazepam: 4.69 ± 0.89 mg and fentanyl: 57 ± 40 µg. Complete lead-extraction was achieved in 110 (85%) leads, partial lead-extraction (<4 cm-fragment remaining) in 5 (4%) leads. Sedation-related hypotension requiring IV fluids occurred in 2 (managed without adverse-consequences) and hypoxia requiring additional airway-management in none. No procedural deaths occurred, one patient required emergency cardiac surgery for localized ventricular perforation, nine had minor complications (transient hypotension/bradycardia/pericardial effusion not requiring intervention).

CONCLUSION

TLE undertaken using LA/conscious-sedation was safe/feasible in our series and associated with good clinical outcome/low procedural complications. Reduced risk of aerosolization of COVID-19 and quicker patient recovery/reduced anesthetic risk are potential benefits that warrant further study.

Aortic valve neocuspidization with autologous pericardium in adult patients: UK experience and meta-analytic comparison with other aortic valve substitutes

OBJECTIVES

We sought to provide further evidence on the safety and efficacy of aortic valve neocuspidization (AVNeo) using autologous pericardium in adult patients with aortic valve disease by reporting clinical and echocardiographic results from the first UK experience and performing a meta-analytic comparison with other biological valve substitutes.

METHODS

We reported clinical and echocardiographic outcomes of 55 patients (mean age 58 ± 15 years) undergoing AVNeo with autologous pericardium in 2 UK centres from 2018 to 2020. These results were included in a meta-analytic comparison between series on AVNeo (7 studies, 1205 patients, mean weighted follow-up 3.6 years) versus Trifecta (10 studies, 8705 patients, 3.8 years), Magna Ease (3 studies, 3137 patients, 4.1 years), Freedom Solo (4 studies, 1869 patients, 4.4 years), Freestyle (4 studies, 4307 patients, 7 years), Mitroflow (4 studies, 4760 patients, 4.1 years) and autograft aortic valve (7 papers, 3839 patients, 9.1 years).

RESULTS

In the present series no patients required intraoperative conversion. After mean follow-up of 12.5 ± 0.9 months, 3 patients presented with endocarditis and 1 required reintervention. The remaining patients had absent or mild aortic valve insufficiency with very low peak and mean transvalvular gradients (16 ± 3.7 and 9 ± 2.2 mmHg, respectively). Meta-analytic estimates showed non-significant difference between AVNeo and all but Magna Ease valves with regards to structural valve degeneration, reintervention and endocarditis. When compared Magna Ease valve, AVNeo and other valve substitutes showed an excess of valve-related events.

CONCLUSIONS

AVNeo is safe, associated with excellent haemodynamic profile. Its midterm risk of valve-related events is comparable to most biological valve substitutes. Magna Ease is potentially the best biological choice as far as risk of reintervention is concerned.

Large sinus of Valsalva aneurysm presenting as acute coronary syndrome

A sinus of Valsalva aneurysm is a rare defect that is usually asymptomatic. We report a sinus of Valsalva aneurysm arising from the left coronary sinus with compression of the left main coronary artery in a 56-year-old man who presented with worsening chest pain. Coronary imaging revealed a 4.6-cm sinus of Valsalva aneurysm with compression of the left main stem, left anterior descending, and proximal circumflex arteries. He underwent aortic root and ascending aortic replacement. Large sinus of Valsalva aneurysms can be life-threatening and can be managed safely surgically.

The utility of 18F-fluorodeoxyglucose positron emission tomography with computed tomography in Mycobacterium chimaera endocarditis: a case series

Background

Infective endocarditis secondary to Mycobacterium chimaera can present with classical constitutional symptoms of infective endocarditis but can be blood culture negative and without vegetations on transthoracic or transoesophageal echocardiogram. Patients with prosthetic valves are at particularly high risk.

Case summary

We present two patients who were diagnosed with infective endocarditis secondary to M. chimaera infection. They presented similarly with pyrexia of unknown origin and night sweats. Both patients had previously undergone aortic valve replacement; one with a tissue valve and the other with a metallic valve. New cardiac murmurs were evident on auscultation, but clinical examination showed no peripheral stigmata of endocarditis. Transoesophageal echo and transthoracic echo were both unremarkable, as were serial blood cultures. FDG PET CT scan was the key investigation, which showed increased uptake in the spleen beside other areas. Histopathology and mycobacterial cultures confirmed the diagnosis of M. chimaera infection in both cases. The first patient completed medical therapy and is now fit and well. However, the second patient unfortunately developed disseminated infection causing death.

Discussion

The management of M. chimaera infective endocarditis is challenging, often with delayed diagnosis and poor outcomes. In the context of negative blood cultures and inconclusive echocardiograms where there remains a high index of suspicion for endocarditis, FDG PET CT scanning can be a crucial diagnostic importance and should be considered early in patients with prosthetic valves.

Type B aortic dissection repair using a Thoraflex hybrid prosthesis in a setting of aberrant left vertebral artery

Type B aortic dissection (TBAD) is often managed conservatively with intervention reserved for complicated cases. Strategies for complicated and uncomplicated TBAD can involve optimal medical therapy, thoracic endovascular aortic replacement and open surgical repair of TBAD with replacement of the affected segment of aorta and reimplantation of aortic branches. The frozen elephant trunk technique has been reported to be a successful surgical strategy in patients with complicated TBAD, particularly in patients who possess unfavourable aortic arch anatomy for endovascular stenting or at increased risk of retrograde Type A aortic dissection. The Thoraflex is a commercially available aortic graft, manufactured by Vascutek®. We describe a successful case of addressing complicated TBAD with rare variant aortic anatomy using a Thoraflex hybrid frozen elephant trunk graft and reimplantation of the aberrant left vertebral artery to the perfusion limb of the Thoraflex graft.

Minimising the risk of Mycobacterium chimaera infection during cardiopulmonary bypass by the removal of heater-cooler units from the operating room

Introduction:

Mycobacterium chimaera ( M. chimaera) is a recently characterised bacterium that can cause life-threatening infections in small numbers of patients who undergo cardiopulmonary bypass during cardiac surgery. The likely mode of transmission is thought to occur through aerosolisation from contaminated water reservoirs. The airborne bacteria then contaminate the surgical field, leading to an infection months or even years later. The preferred practical solution to disrupt the transmission of these airborne bacteria to the patient is to remove the heater-cooler units (HCUs) from the operating room (OR). We describe a process of achieving this in order to provide information to guide other institutions who wish to do a similar thing.

Methods:

A multidisciplinary team was assembled to work on the project. The planning phase involved trialling different OR layouts and simulating the alterations in the HCU circuit function. The changes to the OR were made over a weekend to minimise disruption to the operating schedule.

Results:

The HCU was moved to the dirty utility room adjacent to the OR. Standard operating procedures (SOP) and risk assessments were made to enable this to be used for a dual purpose. One of the ORs was reconfigured to allow the cardiopulmonary bypass machine to be located close to the HCU in the dirty utility room. The total cost of the alterations was £6,158. Although we have provided a physical barrier to interrupt patient exposure to aerosolised M. chimaera from HCUs, we continue to perform cultures and decontamination as per the national recommendations. The SOP was designed to be auditable to ensure compliance with the protocols.

Conclusions:

We show a method by which the HCU can be removed from the OR in a relatively low-cost, straightforward and practical manner.

Left Ventricular Aneurysmectomy: Tailored Scar Excision and Linear Closure

Coronary artery bypass surgery with or without aneurysmectomy is used to treat patients with left ventricular aneurysm. There is debate about patient selection and the appropriate surgical technique. We analyzed the results of 102 consecutive patients who underwent left ventricular aneurysmectomy and reconstruction using a modified linear closure technique between 1992 and 2003. The mean age was 62 years, 81% of the patients were male, and 47% had an ejection fraction < 35%. The locations of the left ventricular aneurysms were anteroapical (75%), apical (21%), and posteroinferior (4%); 23% contained thrombi. Additional procedures included aortic valve replacement in 4, mitral valve repair in 1, and coronary bypass grafting in 98 patients; 3 underwent isolated repair of left ventricular aneurysm. Hospital mortality was 7% and long-term survival was 76% at a mean follow-up of 39 months. Most patients improved symptomatically postoperatively. Left ventricular aneurysm repair with tailored scar excision and a modified closure technique is associated with acceptable mortality and long-term survival.

Hiatal hernia causing extrapericardial tamponade after coronary bypass surgery

Cardiac tamponade is defined as compression of the heart due to accumulation of fluid in the pericardial sac, leading to raised pericardial pressures with haemodynamic compromise. We describe the case of a 76-year old female patient who underwent a routine off-pump coronary artery bypass graft operation and within 48 h developed classic signs of cardiac tamponade. The perioperative echocardiogram and operative findings at re-exploration revealed no clots or fluid collection. A giant hiatus hernia was found to be responsible for the tamponade through extrinsic compression. After insertion of a nasogastric tube and decompression of the stomach, there was a rapid improvement of the clinical picture. The remaining postoperative course was uneventful and the patient was discharged 5 days later, with referral to the general surgeon for further management. We conclude that, in cases of tamponade post-cardiac surgery, extrapericardial pathologies should be considered.

Primary Right Atrial Angiosarcoma

A rare case of right atrial angiosarcoma is described in a 55-year-old man who was admitted with acute chest pain. Electrocardiography, cardiac enzymes, and chest radiography were negative. His pain settled and he was discharged, but readmitted 15 days later with clinical features of cardiac tamponade. Computed tomography demonstrated a large pericardial effusion. Emergency surgery was performed to excise a right atrial tumor, which histology confirmed to be an angiosarcoma.

Aortic valve replacement with simultaneous chest wall reconstruction for radiation-induced sarcoma

Sarcomas, a rare complication of radiotherapy for breast carcinoma, have a poor prognosis. We describe a lady with previous mantle radiotherapy exposure, who developed a radiation-induced chest wall sarcoma. She underwent simultaneous aortic valve replacement (AVR) for severe aortic stenosis and excision of the sarcoma. Chest wall reconstruction was achieved with a composite marlex cement plate and a pedicled latissimus dorsi muscle flap.

Fatal early acute thrombosis of mechanical mitral prosthesis

OBJECTIVE

To report a rare case of fatal early acute thrombosis of mechanical mitral prosthesis.

METHODS

A 62-year-old lady, who underwent closed mitral valvotomy for rheumatic heart disease 19 years ago, presented with Canadian Cardiovascular Society Class II angina and New York Heart Association Class III dyspnoea. Investigations including echocardiogram and cardiac catheterisation revealed mixed mitral valve disease. She had severe pulmonary artery hypertension with pulmonary artery wedge pressure of 35 mm of mercury. Significant stenosis in the midportion of dominant right coronary artery was also demonstrated. She underwent mitral valve replacement using mechanical tilting disc prosthesis, DeVega tricuspid annuloplasty and saphenous vein bypass graft to the distal right coronary artery. After having made satisfactory early postoperative progress, she suffered an asystolic cardiac arrest about 26 h postoperatively.

RESULTS

The patient succumbed despite all resuscitative measures. Autopsy revealed an adherent thrombus occluding the atrial surface of the minor orifice of mechanical prosthesis, which prevented the valve from functioning.

CONCLUSION

To the best of our knowledge, this is the first case of prosthetic valve thrombosis (PVT) occurring on the first postoperative day in a patient with a mechanical valve prosthesis, without any circulatory assist device.

Isolated severe ischemic tricuspid regurgitation: successful surgical repair

Tricuspid regurgitation (TR) is a common association of left-sided valvular lesions that is occasionally seen with ischemic heart disease. However, isolated ischemic TR requiring surgical intervention is extremely rare, with very few reported cases. The case is presented of a 59-year-old woman who, after extensive non-cardiac investigations, was eventually diagnosed with severe functional TR due to chronic myocardial ischemia. The patient underwent successful surgical treatment.

Transfusion related acute lung injury in cardiac surgery

Transfusion related acute lung injury (TRALI) is an uncommon complication following administration of blood products. It is often difficult to differentiate from other commoner causes of cardio-respiratory instability. However, prompt diagnosis and management is associated with favorable outcome.

Saphenous vein patch plasty to correct saphenous graft and aortotomy mismatch

Mismatch of aortotomy and saphenous vein graft size occasionally occurs and can compromise the contour of the anastomosis thereby jeopardising its patency. We describe an alternative technique of saphenous vein patch plasty to overcome this complication by giving a more desirable hooded contour to the anastomosis. This results in improved graft patency, hemostasis and clinical outcome.

Heparin induced thrombocytopenia type II complicating coronary artery bypass surgery: a tale of caution

OBJECTIVE

To highlight an uncommon problem of heparin induced thrombocytopenia after coronary artery bypass operation.

METHODS

We report the case of a 59-year-old man who suffered severe type II heparin induced thrombocytopenia (HIT) after coronary artery bypass operation. He experienced extensive skin necrosis at sites of saphenous vein harvesting, which progressed to cause soft tissue necrosis of both feet. He also exhibited secondary clinical features arising from pulmonary, hepatic and renal dysfunction suggestive of extensive venous thrombosis. Primary treatment of the haematological disorder was achieved by discontinuation of all forms of heparin and the administration of a heparinoid intravenously. Secondary treatment included forefoot amputations and skin grafting.

RESULTS

Though the patient suffered a protracted period of recovery he was discharged home well.

CONCLUSION

We have reported this complex case in order to familiarise cardiothoracic surgeons with the extreme characteristics of type II HIT and to emphasise that early diagnosis and treatment will facilitate a successful outcome.