Multi-modality imaging assessment of microbubbles and cerebral emboli in left ventricular pulsed field ablation

BACKGROUND

Pulsed field ablation (PFA) may have a superior safety profile compared to other technologies, but it has the potential to cause gaseous microbubbles (MB), which may be associated with cerebral emboli. Limited relative safety data has been published regarding PFA in the left ventricle (LV).

METHODS

Healthy and chronic myocardial infarction (MI) swine underwent PFA (monopolar, biphasic, 25 Amps) in the LV using an irrigated focal catheter under intra-cardiac echocardiography (ICE) guidance for MB monitoring. Two control swine received air MBs through the lumen of the ablation catheter. Swine underwent brain MRI before and after PFA (or control air MB injection). Gross pathology and histology of brains with abnormal MRI findings were performed.

RESULTS

Four healthy and 5 chronic MI swine underwent 124 left ventricular PFA applications. No PFA-related MB formation was noted on ICE. Both control swine developed multiple acute emboli in the thalamus and caudate on DWI, ADC, and FLAIR brain MRI images in response to air MB injection. Of the 9 PFA swine, there were no abnormalities on ADC or FLAIR images. There was one hyperintense focus in the left putamen on the DWI trace image, but the absence of ADC or FLAIR affirmation suggested it was artifact. Gross pathology and histopathology of this region did not detect any abnormalities.

CONCLUSIONS

Focal monopolar biphasic PFA of both healthy and chronically infarcted left ventricular myocardium does not generate any MB or cerebral emboli observable on ICE and brain MRI.

Absence of (sub-)acute cerebral events or lesions after electroporation ablation in the left-sided canine heart

BACKGROUND

Irreversible electroporation (IRE) is a nonthermal ablation modality. A 200-J application can create deep myocardial lesions, but gas bubbles are created at the ablation electrode. Cerebral effects of these bubbles are unknown.

OBJECTIVE

The purpose of this study was to investigate gas microemboli-induced brain lesions after IRE and radiofrequency (RF) ablation to the left side of the canine heart, using magnetic resonance imaging (MRI) and histopathology.

METHODS

In 11 canines, baseline cerebral MRI scans were performed. In 9 animals, after retrograde femoral artery access, 12 ± 4 200-J IRE applications were administered in the ascending aorta. In 2 animals, 30 minutes of irrigated 30-W RF ablation using 10-30g of contact force was applied in the left ventricle. At days 1 and 5 after ablation, MRI was repeated. The brain tissue then was histopathologically examined.

RESULTS

All ablations and follow-up were uneventful. Intracardiac echography confirmed gas bubble formation after each IRE application. Neurologic examination was normal. MRI scans were normal in all animals at day 1 and were normal in 10 of 11 animals at day 5. In 1 animal, a single <2-mm-diameter lesion in the right temporal region could not be excluded as a small infarct or early hemorrhagic site. Histopathologic analysis of the same region showed no pathologic changes. In all other animals, gross and microscopic pathology were normal.

CONCLUSION

MRI images alone or in combination with histologic follow-up did not reveal treatment-related embolic events. Gross and microscopic pathology did not reveal evidence of treatment-related embolic events. IRE seems to be a safe ablation modality for the brain.

Mitral stenosis produced by infective endocarditis involving a previously anatomically normal valve

Described herein is a 63-year-old man who developed methicillin-sensitive Staphylococcus aureus endocarditis on a previously anatomically normal mitral valve. The resulting vegetations were so large that severe mitral stenosis resulted. The development of valve stenosis due exclusively to infective endocarditis is extremely rare.

Clinical presentation of multiple cerebral emboli and central retinal artery occlusion (CRAO) as signs of cardiac myxoma

Cardiac myxomas are benign tumors of endocardial origin that usually occur in the left atrium. Trans-thoracic echocardiography is the diagnostic method of choice, and early surgical removal is the preferred method of treatment. We present a patient whose history of cerebral emboli and central retinal artery occlusion (CRAO) led to a diagnosis of cardiac myxoma. Neuroimaging studies showed multiple infarcts in the region of the left middle and anterior cerebral arteries. Ophthalmic examination showed gross retinal pallor compatible with left central retinal artery occlusion (CRAO). The etiology of stroke was investigated by performing trans-thoracic echocardiography, which showed a mass in the left atrium compatible with cardiac myxoma. Complete removal of the cardiac tumor was performed by open-heart surgery. Fortunately, after a period of rehabilitation, the patient's hemiparesis almost completely resolved, but the loss of vision OS remained unchanged. Many cases of myxoma are accompanied by constitutional symptoms, such as anemia, fever and weight loss, which allow for a diagnosis to made before serious complications such as embolism occur. Unfortunately, in some patients, such as ours, the absence of signs and symptoms allows the myxoma to pass completely unnoticed until the first embolic event occurs.

Successful treatment of cerebral emboli with tissue plasminogen activator in a patient with takotsubo cardiomyopathy: A case report

Takotsubo cardiomyopathy is a cardiac syndrome characterized by reversible left ventricular wall motion abnormalities. It mimics the acute coronary syndrome; however, significant obstructive coronary artery disease is absent. The prognosis is relatively favorable in many cases, but complications may occur during the acute stage. Herein, we present a case of takotsubo cardiomyopathy in a 76-year-old woman. Three days after admission for persistent chest pains, the patient suddenly developed right hemiplegia, right homonymous hemianopsia, and aphasia. By diffusion-weighted magnetic resonance imaging and magnetic resonance angiography, we diagnosed acute-phase cerebral infarction caused by abrupt occlusion of the left middle cerebral artery by a thrombus, and treated it with intravenously administered tissue plasminogen activator. Three hours afterward, the patient's condition improved considerably. She was discharged 15 days after admission without any neurological sequelae. Thus, we show that takotsubo cardiomyopathy complicated by cerebral emboli can be successfully treated using tissue plasminogen activator. .

Septic Cerebral Embolisation in Fulminant Mitral Valve Infective Endocarditis

A 37-year-old male with known intravenous drug use was admitted with an acute onset of worsening confusion and speech impairment. His vitals and biochemical profile demonstrated severe sepsis, with a brain CT showing several lesions suspicious for cerebral emboli. He then went on to have a bedside transthoracic echocardiogram that was positive for vegetation on the mitral valve, with associated severe mitral regurgitation. Unfortunately, before he was stable enough to be transferred for valve surgery, he suffered an episode of acute pulmonary oedema requiring intubation and ventilation on intensive care unit.

Investigation of risks for cerebral embolism associated with the hemodynamics of cardiopulmonary bypass cannula: a numerical model

Cerebral emboli originating in the ascending aorta are a major cause of noncardiac complications following cardiac surgery. The hemodynamics of the aortic cannula has been proven to play a significant role in emboli generation and distribution. The aim of the current study was to perform a thorough numerical investigation in order to examine the effect of the design and orientation of the cannula used during cardiopulmonary bypass on the risk to develop cerebral embolism. Hemodynamic analyses compared numerical models of 27 cases consisting of six different cannula orientations, four aortic anatomies, and three cannula designs. The cannula designs included a straight-tip (ST) cannula, a moderately curved tip cannula (TIP1 ), and a sharp-angle curved cannula (TIP2 ). Outcome measures included hemodynamic parameters such as emanating jet velocity, jet velocity drop, maximal shear stress, aortic wall reaction, emboli pathlines and distribution between upper and lower vessels, and stagnation regions. Based on these parameters, the risks for hemolysis, atheroembolism, and cerebral embolism were evaluated and compared. On one hand, the jet emerging from the ST cannula generated large wall-shear stress at the aortic wall; this may have triggered the erosion and distribution of embolic atheromatous debris from the aortic arch. On the other hand, it diverted more emboli from the clamp region to the descending aorta and thus reduced the risk for cerebral embolism. The TIP1 cannula demonstrated less shear stress on the aortic wall and diverted more emboli from the clamp region toward the upper vessels. The TIP2 cannula exhibited a stronger emanating jet, higher shear stress inside the cannula, and highly disturbed flow, which was more stagnant near the clamp region. Current findings support the significant impact of the cannula design and orientation on emboli generation and distribution. Specifically, the straight tip cannula demonstrated a reduced risk of cerebral embolism, which may be pivotal in the clinical setting.