Cardiac Resynchronisation Therapy: The Role of Echocardiography in Patient Selection and Follow-up

Resynchronisation of segmental left ventricular mechanics as well as re-coordination of both atrioventricular and interventricular mechanics are potential mechanisms for the clinical improvement observed in patients undergoing cardiac resynchronisation therapy (CRT) for heart failure. Resynchronisation therapy is approved in patients with refractory heart failure symptoms despite optimal medical therapy. The presence of a prolonged QRS duration has been the main criterion used to identify ventricular dyssynchrony. However, based on the current selection criteria, about 20% to 30% of patients do not improve after biventricular pacing. Using echocardiography, dyssynchrony may be absent in some heart failure patients with a wide QRS, or present in those with a normal QRS interval. Echocardiography, and especially the more sophisticated techniques based on Tissue Doppler Imaging, may improve patient selection by identifying inter- and intra-ventricular dyssynchrony. Echocardiography can also be used to optimise lead placement. Following pacemaker implantation, various echocardiographic techniques can be used to ensure optimal cardiac resynchronisation and to monitor improvements in left ventricular function and hemodynamics. In this review, the different echocardiographic approaches to predict patient response to CRT are discussed. In addition, the use of echocardiography to guide lead positioning and to optimise pacemaker settings following pacemaker implantation is discussed

Sad hearts in heart failure patients

Heart failure is a common clinical entity. Because patients with heart failure face high rates of debilitation and mortality, the study of depression characteristics in this population is a critical research area in the pursuit of improved quantity and quality of their lives. Studies have shown that depression is common in heart failure and, interestingly, that both conditions share similar pathobiological mechanisms. Depression in heart failure is a serious co-morbidity. It is a strong predictor of short-term worsening of heart failure symptoms, a decline in health status, mortality and re-hospitalization, independent of baseline ventricular function and severity of cardiovascular disease. Depression remains poorly recognized and under-treated in heart failure. The presence of depression is not random. It is disproportionately diagnosed amongst patients who are female, those suffering more advanced disease, those who are socially isolated and those of low socioeconomic status. Patients should be screened regularly for symptoms of depression. Although effective treatment is available, no studies have been done to show that treatment of depression has a positive impact on heart failure outcome

Geology of the South-Eastern Richtersveld

In their recent study or the geology of the, Richtersveld, de villiers and. Sohnge (1959) _have shown that ' the south-eastern ·part or this area is geologically complex, and contains numerous problems that can only be solved by detailed study. 'The .present investigation is an attempt - to find solutions ·to contoured geological -problems, as possible and thus increase our knowledge of the geology _of the lt1ehtersveld an area that forms a link between· the geology of the- western Cape and southwest Africa. During _ the present investigation a. contoured geological map of the south-eastern Richtersveld on a scale of 1:25,000, was constructed. 'Four hundred and graphic modal analyses ·were .made; and twenty-five chemical analyses were used, fourteen were new, and the remaining eleven were taken from the Richtersveld Memoi

Excessive vasoconstriction in rheumatic mitral stenosis with modestly reduced ejection fraction

AbstractObjectives. The primary hypothesis examined was that underfilling due to inflow obstruction accounts for modestly depressed ejection performance in mitral stenosis, Having found little evidence to support this hypothesis, we sought to determine other factors that might differentiate patients with different levels of ejection performance.Methods. Ventricular load and performance were compared in two groups of patients before and immediately after successful balloon valvuloplasty that was not complicated by mitral regurgitation: those in whom prevalvuloplasty ejection fraction was ≥0.55 (group I, n = 10) and those in whom it was <0.55 (group II, n =11).Results. Before valvuloplasty, mitral valve area was less in group II (0.65 cm2) than in group I (0.84 cm2, p = 0.02), but end-diastolic pressure (12 vs. 12 mm Hg in group I), end-diastolic wall stress (46 vs. 44 kdynes/cm2in group I) and end-diastolic volume (152 vs. 150 ml in group I) were not less in group II, nor were these variables significantly reduced compared with those of a normal control group. In group II, end-systolic volume was larger (77 vs. 55 ml in group I, p = 0.001) and cardiac output was less (3.1 vs. 3.6 liters/min in group I, p = 0.03), possibly owing to higher systemic vascular resistance (2,438 vs. 1,921 dynes·s·cm−5in group I, p = 0.05) and end-systolic wall stress (273 vs. 226 kdynes/cm2in group I, p = 0.06), although mean arterial pressure in the two groups was similar (91 vs. 84 mm Hg in group I, p = 0.22). Group II patients also had higher values for pulmonary vascular resistance (712 vs. 269 dynes·s·cm−5in group I, p = 0.03) and mean pulmonary artery pressure (47 vs. 29 mm Hg in group I, p = 0.02) despite similar values for mean left atrial pressure (20 vs. 18 mm Hg in group I, p = 0.35). After valvuloplasty, mitral valve area increased by 2.5- and 3-fold, respeditely, in group I (to 2.1 cm2and group II (to 2.0 cm2). Modest increases in left ventricular end-diastolic pressure, end-diastolic stress and end-diastolic volume (+9%) after valvuloplasty were statistically significant only for group II. End-systolic wall stress did not decline in either group II (281 kdynes/cm2) or group I (230 kdynes/cm2), and ejection fraction failed to increase significantly (0.49 to 0.51 for group II and 0.62 to 0.61 for group I) after valvuloplasty. Contractile performance estimated with a preload-corrected ejection fraction-afterload relation was within or near normal limits in all 19 patients in whom it was assessed.Conclusions. Excessive vasoconstriction may account for the higher afterload, lower ejection performance and tower cardiac output observed in a subset of patients with mitral stenosis because contractile dysfunction could not be detected and left ventricular filling—which was not subnormal despite severe inflow obstruction—improved only modestly after valvuloplasty

Effect of abrupt mitral regurgitation after balloon valvuloplasty on myocardial load and performance

AbstractThe concept that mitral regurgitation masks myocardial dysfunction by reducing afterload and augmenting ejection performance has not been well established in humans. The effect of abruptly produced mitral regurgitation on left ventricular loading and performance was therefore evaluated in five patients who developed this complication after an otherwise successful percutaneous balloon mitral valvuloplasty. Mitral valve area by Gorlin formula calculated with forward flow increased from 0.92 ± 0.14 to 2.75 ± 0.82 cm2. Mean left atrial pressure did not decrease (19 ± 4 to 19 ± 6 mm Hg). The size of the left atrial Vwave relative to mean left atrial pressure (peak V— mean left atrial pressure) increased from 7 ± 4 to 19 ± 6 mm Hg. Angiographic mitral regurgitation increased from 0+ or 1 + to >3+ in each patient and regurgitant fraction increased from 0.23 ± 0.11 to 0.55 ± 0.99 (p < 0.01).End-diastolic volume increased modestly from 148 ± 15 to 159 ± 15 ml (p = NS). Heart rate increased from 54 ± 5 to 71 ± 8 heats/min (p < 0.05), which may have prevented further increases in preload by shortening the filling period. End-systolic stress decreased by 32% from 277 ± 34 to 188 ± 52 kdyn/cm2(p < 0.01) as a result of a 25% decrease in end-systolic pressure from 121 ± 8 to 91 ± 7 mm Hg and a 16% decrease in end-systolic volume from 67 ± 13 to 56 ± 8 ml (p = NS). Contractility estimated from the preload-corrected ejection fraction-afterload relation decreased in one of the five patients and did not increase in the others despite an increase in heart rate, possibly as a result of myocardial depression from the balloon procedure itself. Nevertheless, the decrease in end-systolic volume could not be attributed to a net increase in contractility. The result of the changes in loading was an increase in ejection fraction from 0.55 ± 0.05 to 0.65 ± 0.04 (p < 0.05).Thus, abruptly produced mitral regurgitation increases ejection performance by reducing afterload without increasing contractility. This should be taken into consideration when anticipating the results of valve replacement for acute or subacute mitral regurgitation

New constraints on the Cretaceous geodynamics of paleo-Pacific plate subduction: Insights from the Xiaojiang–Beizhang granitoids, Zhejiang Province, southeast China

The relationship between the evolution of Cretaceous magmatism along the southeastern margin of Eurasia and subduction of the paleo-Pacific plate remains controversial. Here we investigate the petrogenesis of the Xiaojiang–Beizhang ferroan and magnesian granitoids, melanocratic microgranular enclaves (MME) that are found within the granitoids, and an associated mafic dyke exposed in southeast China to provide new constraints on the geodynamics of paleo-Pacific plate subduction. Zircon U–Pb ages indicate that the ferroan and magnesian granitoids were emplaced in the Cretaceous (ca. 120 and 110 Ma, respectively), and that the MME and mafic dyke are coeval with their host granitoids. Geochemical characteristics imply that the granitoids were produced by partial melting of crustal rocks and mixed with mantle-derived magmas. The MME are derivatives of the mafic magmas that intruded the silicic magmas. Two phases of mafic magmatism are evident. Stage 1 mafic rocks (the ca. 120 Ma MME) were derived mainly from the subcontinental lithospheric mantle (SCLM) with some contribution from asthenospheric mantle. The parental mafic magmas for Stage 2 (the ca. 110 Ma MME and mafic dykes) were derived from interaction and metasomatism of the SCLM and asthenosphere with slab-derived fluids. Iron enrichment or depletion in the granitoids was controlled mainly by oxygen fugacity and pressure. Our new data, combined with previously published data from Cretaceous igneous rocks in southeastern China, reveal major geochemical changes at 136 and 118 Ma, respectively. The 132–119 Ma igneous rocks record the minimal addition of slab-derived components to their source, and provide strong evidence for an abrupt change in the direction of motion of the paleo-Pacific plate from southwest to northwest at ca. 125–122 Ma

Evaluating the importance of metamorphism in the foundering of continental crust

The metamorphic conditions and mechanisms required to induce foundering in deep arc crust are assessed using an example of representative lower crust in SW New Zealand. Composite plutons of Cretaceous monzodiorite and gabbro were emplaced at ~1.2 and 1.8 GPa are parts of the Western Fiordland Orthogneiss (WFO); examples of the plutons are tectonically juxtaposed along a structure that excised ~25 km of crust. The 1.8 GPa Breaksea Orthogneiss includes suitably dense minor components (e.g. eclogite) capable of foundering at peak conditions. As the eclogite facies boundary has a positive dP/dT, cooling from supra-solidus conditions (T > 950 ºC) at high-P should be accompanied by omphacite and garnet growth. However, a high monzodioritic proportion and inefficient metamorphism in the Breaksea Orthogneiss resulted in its positive buoyancy and preservation. Metamorphic inefficiency and compositional relationships in the 1.2 GPa Malaspina Pluton meant it was never likely to have developed densities sufficiently high to founder. These relationships suggest that the deep arc crust must have primarily involved significant igneous accumulation of garnet–clinopyroxene (in proportions >75%). Crustal dismemberment with or without the development of extensional shear zones is proposed to have induced foundering of excised cumulate material at P > 1.2 GPa

The chemically zoned 1949 eruption on La Palma (Canary Islands): Petrologic evolution and magma supply dynamics of a rift zone eruption

The 1949 rift zone eruption along the Cumbre Vieja ridge on La Palma involved three eruptive centers, 3 km spaced apart, and was chemically and mineralogically zoned. Duraznero crater erupted tephrite for 14 days and shut down upon the opening of Llano del Banco, a fissure that issued first tephrite and, after 3 days, basanite. Hoyo Negro crater opened 4 days later and erupted basanite, tephrite, and phonotephrite, while Llano del Banco continued to issue basanite. The eruption ended with Duraznero erupting basanite with abundant crustal and mantle xenoliths. The tephrites and basanites from Duraznero and Llano del Banco show narrow compositional ranges and define a bimodal suite. Each batch ascended and evolved separately without significant intermixing, as did the Hoyo Negro basanite, which formed at lower degrees of melting. The magmas fractionated clinopyroxene +olivine±kaersutite±Ti-magnetite at 600–800 MPa and possibly 800–1100 MPa. Abundant reversely zoned phenocrysts reflect mixing with evolved melts at mantle depths. Probably as early as 1936, Hoyo Negro basanite entered the deep rift system at 200–350 MPa. Some shallower pockets of this basanite evolved to phonotephrite through differentiation and assimilation of wall rock. A few months prior to eruption, a mixing event in the mantle may have triggered the final ascent of the magmas. Most of the erupted tephrite and basanite ascended from mantle depths within hours to days without prolonged storage in crustal reservoirs. The Cumbre Vieja rift zone differs from the rift zones of Kilauea volcano (Hawaii) in lacking a summit caldera or a summit reservoir feeding the rift system and in being smaller and less active with most of the rift magma solidifying between eruptions