Andrew Yoon

New options in noninvasive assessment of left ventricular torsion

The complex, intricate 3D pattern of ventricular torsion has both fascinated and perplexed scientists for centuries. The identity of the underlying anatomic myocardial unit responsible for this pattern of contraction continues to be an arena of debate. While the complicated wringing motions involved in torsion are difficult to quantify, several techniques have been demonstrated to be effective in the noninvasive assessment of left ventricular (LV) torsion. Magnetic resonance tissue-tagging with dynamic MRI is the gold standard for the noninvasive quantitative evaluation of torsion with high spatial and temporal resolution. However, this is a technically involved and potentially time-consuming process. Echocardiography is another alternative noninvasive method. Both tissue Doppler imaging and speckle-tracking imaging have been shown to be sufficiently accurate and reliable alternatives to MRI in the noninvasive assessment of LV torsion. While the potential applications of these techniques to assess LV torsion appears boundless, further studies are needed to validate measures of LV torsion by the additional, but most important, test of demonstrating its clinical utility as a predictor of prognosis.

Left Ventricular Torsional Mechanics in Uncomplicated Pregnancy

Alterations in left ventricular (LV) twist (torsion) and untwist have been described for a variety of physiologic and pathologic conditions. Little information is available regarding changes in these parameters during normal pregnancy.

Assessment of segmental myocardial blood flow and myocardial perfusion reserve by adenosine-stress myocardial arterial spin labeling perfusion imaging.

To determine the feasibility of measuring increases in myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) on a per‐segment basis using arterial spin labeled (ASL) magnetic resonance imaging (MRI) with adenosine vasodilator stress in normal human myocardium.

Noninvasive measurement and clinical relevance of myocardial twist and torsion

Left ventricular (LV) torsion (twisting) and untwisting results in equalization of wall stress and augmentation of pressure generated for a given shortening of sarcomere during the systolic contraction and aids early diastolic relaxation. This is attributed to the dynamic interaction of epicardial and endocardial helical myocardial fibers. Recent advances in noninvasive imaging techniques have enabled us to quantify torsion accurately and reliably in health and disease. LV torsional mechanics are altered in range of clinical conditions from those that cause minimal cardiac architectural changes as seen in hypertension, diabetes mellitus or older age to advanced cardiac remodeling as seen dilated or hypertrophic cardiomyopathy. Therefore, assessment of LV rotational mechanics may be a potentially sensitive marker of cardiac dysfunction and may provide important insights into the pathophysiology of heart failure.

Double-gated myocardial ASL perfusion imaging is robust to heart rate variation

Cardiac motion is a dominant source of physiological noise (PN) in myocardial arterial spin labeled (ASL) perfusion imaging. This study investigates the sensitivity to heart rate variation (HRV) of double‐gated myocardial ASL compared with the more widely used single‐gated method.

Arterial spin labeling CMR perfusion imaging is capable of continuously monitoring myocardial blood flow during stress

Background Myocardial arterial spin labeling (ASL) is a non-invasive non-contrast CMR perfusion imaging technique [Zun et al., ‘09] that is compatible with adenosine stress testing [Zun et al., ‘11]. Here, we demonstrate its ability to continuously monitor MBF during stress, which has a variety of potential applications including interventional CMR and the study of endothelial function. We used mild sustained isometric handgrip stress.

Churg-Strauss Syndrome Presenting As Acute Necrotizing Eosinophilic Myocarditis. Concise review of the literature.

BACKGROUND Acute eosinophilic myocarditis (EM) is a rare form of heart failure that is characterized by myocardial eosinophilic infiltration usually in association with peripheral eosinophilia. The underlying cause is variable and can include allergic reactions, parasitic infection, idiopathic hypereosinophilic syndrome, malignancy, Loefflers syndrome, Churg-Strauss syndrome (CSS), early giant cell myocarditis and malignancy. The course is potentially fatal, and early diagnosis and treatment with steroids is essential. CONCLUSION Here, we present an illustrative case of eosinophilic myocarditis secondary to CSS followed by a brief review of epidemiology, pathogenesis, diagnosis and treatment of both disease entities.

Patent foramen ovale and neurologic events in patients undergoing liver transplantation

BACKGROUND Patent foramen ovale (PFO) is present in approximately 20% of individuals. During liver transplantation (LT), intra-operative transesophageal echocardiography can observe transient intra-cardiac shunting of atheromatous debris via a PFO. Closure of PFOs prior to LT has thus been suggested as a potential treatment to reduce peri-operative cerebral vascular accident (CVA). The objective of this study was to assess if the presence of PFO is associated with CVA in patients undergoing LT. METHODS Three hundred fifty-eight patients undergoing LT at a single academic institution were included. All patients underwent standardized cardiac evaluation including a detailed cardiovascular history and physical examination, electrocardiogram and transthoracic echocardiogram. Five patients were excluded because of poor transthoracic echocardiographic image quality, and three patients were excluded because of PFO closure prior to LT, yielding a study population of 350 patients. Medical records were reviewed to determine demographics, echocardiographic findings and outcome following LT. Major adverse cardiovascular events, myocardial infarction, CVA and death were collected. RESULTS Mean age was 53.4 ± 10.2 years; 61% male and 5% of patients had a prior history of CVA. Alcohol and hepatitis C were the most common etiologies for liver disease. Forty-six patients (13.1%) were diagnosed with PFO prior to LT. In-hospital CVA occurred in 6 patients (1.7%). The prevalence of a CVA was not significantly higher in patients with PFO compared to patients without PFO, 2.2% vs 1.6%, p = 0.57. In-hospital mortality was similar in patients with PFO compared to patients without PFO, 4.4% and 5.3%, p = 1.0. CONCLUSIONS The presence of a PFO in patients undergoing LT is not associated with postoperative CVA. Prophylactic closure of PFOs, in the absence of other indications, does not appear to be warranted in patients undergoing LT.

Effects of pressure variation and atrial fibrillation on CardioMEMS™ HF measured pulmonary artery diastolic pressure: comparison of device-averaged and visually inspected waveforms

OBJECTIVE Heart failure (HF) management guided by implantable hemodynamic monitoring reduces hospitalization rates. Hemodynamic data from the CardioMEMS™ HF system includes device-averaged pulmonary artery pressures (PAP) and heart rate. Agreement of device-averaged values compared to the standard method of visual inspection of pressure waveforms at end-expiration is unknown. We evaluated the agreement between device-averaged and visually inspected end-expiratory PAP. APPROACH Twenty-one patients implanted with the CardioMEMS™ HF system were evaluated. Eight-hundred twenty-three PAP waveforms from the Merlin remote monitoring website were visually inspected and pulmonary artery systolic pressure (PASP) and pulmonary artery diastolic pressure (PADP) at end-expiration were recorded. Waveforms were evaluated for pressure variation (PV), defined as the difference between highest and lowest PASP measurement of  ⩾20 mmHg. Bland-Altman analysis quantified differences between device-averaged and visually inspected waveforms. MAIN RESULTS All patients were NYHA functional class III, mean age was 67  ±  15 years and 15 (71%) had AF. Bland-Altman analysis of all waveforms revealed a mean-difference in PADP of  -1.4 mmHg, indicating that visually inspected values were higher than device-averaged values. For PV  ⩾20 mmHg, this value increased to  -2.8 mmHg. The mean-difference comparing waveforms from patients with or without AF was  -1.3 and  -1.6 mmHg, respectively. The 95% limits of agreement were  >50% wider for waveforms from patients with versus without AF (10.3 versus 6.7 mmHg). SIGNIFICANCE There is good agreement between device-averaged and visually inspected waveforms when pressure variation is  <20 mmHg and for patients without atrial fibrillation.

Echocardiographic Imaging in Adult Congenital Heart Disease

Echocardiography (echo) remains the primary imaging modality for the anatomical and basic functional assessment of the heart with congenital defects. As with many techniques shared between adult and pediatric cardiology, echo imaging has been adapted to imaging pediatric subjects and concentrates heavily on the structural delineation of cardiac anatomy, both normal and abnormal. Adult echo imaging, alternatively, concentrates primarily on the functional characterization of cardiac structures owing largely to the fact that the majority of adult hearts are structurally normal to begin with. The application of echo imaging to adult congenital heart disease (ACHD) patients requires a strong integration of both approaches to and applications of echo imaging.