Contralateral transvenous left ventricular lead placement of implantable devices with pre-sternal tunnelling in chronically obstructed subclavian veins.

Cardiac resynchronisation therapy (CRT) is a recognised therapy for the management of severe left ventricular dysfunction, advanced congestive cardiac failure (NYHA III or IV), ventricular dyssynchrony (either broad LBBB or mechanical dyssynchrony on echocardiography) and failure of optimal medical therapy to achieve improvement in clinical status. Upgrading right ventricular pacemakers or defibrillators to biventricular devices is common and we describe here, 2 such cases of biventricular upgrade with blocked venous access on the ipsilateral side and successful placement of left ventricular leads following pre-sternal tunnelling from the contralateral side.

Massive pulmonary embolus and a precariously positioned thrombus: teetering on a knife edge!

Pulmonary embolism (PE) is a common condition seen regularly by emergency physicians. The authors describe a patient who presented with shortness of breath and syncope. He also experienced drowsy, clammy and sweaty episodes. He was tachycardic, tachypnoeic and saturating at 92% on air. A chest X-ray was normal but an ECG showed S1Q3T3. A CT pulmonary angiography performed showed bilateral pulmonary emboli with a large inferior vena cava (IVC) thrombus. Echocardiography revealed severely dilated right ventricle and atrium, severe right ventricular impairment, pulmonary hypertension, large mobile friable clots seen extending into the tricuspid valve. A multidisciplinary team decided the safest management approach was intravenous heparin. The patient recovered and repeat echocardiography 5 days later showed significantly smaller clots. The extension of an IVC thrombus into the heart and prolapsing into the tricuspid valve is an extremely rare presentation. Furthermore this case demonstrates the importance of echocardiography when diagnosing and generating bespoke management plans for PE.

Characterisation and reproducibility of a human ex vivo model of thrombosis.

BACKGROUND: The Badimon chamber is a clinical ex vivo model of thrombosis that mimics flow conditions within the coronary circulation of man. The aims of this study were to characterise thrombus formation in the chamber and evaluate its reproducibility. METHODS: Using blood from 24 healthy human volunteers, thrombus formation was assessed at low and high shear rates with porcine aortic tunica media as the thrombogenic substrate. Thrombus area was measured histomorphometrically. Reproducibility was assessed by paired measurements made both within and between days. Platelet activation was assessed before and at selected points within the extracorporeal circuit using flow cytometry, and fibrin content and distribution within the thrombus were assessed by immunohistochemistry. RESULTS: Total thrombus area was highly reproducible within and between days in the low shear ([mean thrombus area, mean difference ± SEM] 8,018µm(2), 58±204µm(2) and 8,177µm(2), -154±168µm(2) respectively) and high shear chambers (11,802µm(2), -52±175µm(2) and 11,877µm(2), 220±181µm(2) respectively). Total thrombus area was greater in the high compared to the low shear chamber (11,970±285µm(2)versus 7,892±298µm(2); P<0.0001). Transit through the extracorporeal circuit did not result in platelet activation which was only detected after blood passed across the perfusion chambers (P=0.02 for platelet-monocyte aggregate formation and P=0.05 for P-selectin expression). Thrombus in the low shear chamber contained a greater proportion of fibrin (25.0±6.0% versus 8.3±1.6%, P<0.001). CONCLUSIONS: The Badimon chamber provides a highly reproducible technique for the assessment of ex vivo platelet-rich thrombus formation in man.

Independent and incremental value of stress echocardiography over clinical and stress electrocardiographic parameters for the prediction of hard cardiac events in new-onset suspected angina with no history of coronary artery disease.

AIMS: Recent data have shown that exercise electrocardiogram (ECG) has no incremental prognostic value over clinical and rest ECG parameters in chest pain patients without a history of coronary artery disease (CAD). The incremental prognostic value of stress echocardiography (SE) in this population is unknown. METHODS AND RESULTS: Accordingly, 547 consecutive patients (68 ± 4.9 years) with chest pain but no previous history of CAD, referred for SE (exercise and dobutamine), were identified. Patients were followed up for death and acute myocardial infarction (AMI). At a median follow-up period of 28 months, there were a total of 35 hard cardiac events (5 deaths and 30 non-fatal AMI). Among the prognostic clinical, resting/stress ECG, and SE data, univariate predictors were the Framingham risk score (P = 0.025), diabetes (P = 0.06), hypercholesterolaemia (P = 0.06), stress ECG ischaemia (P = 0.044), stress heart rate (P = 0.019), and SE-determined ischaemic burden (stress-rest wall thickening score index; P < 0.001). In a multivariate model, ischaemic burden was the only independent predictor of events (P < 0.001). SE also showed incremental prognostic value over and above clinical (Framingham's risk score) and stress ECG changes in a global χ(2) model. This was true also for patients undergoing only exercise SE (n = 347). CONCLUSION: SE provides both independent and incremental prognostic value for the prediction of hard cardiac events in chest pain patients without a previous history of CAD-over and above clinical, ECG, and stress ECG data.

Myocardial contrast echocardiography versus single photon emission computed tomography for assessment of hibernating myocardium in ischemic cardiomyopathy: preliminary qualitative and quantitative results.

BACKGROUND: Single photon-emission computed tomography (SPECT) is widely used for the assessment of hibernating myocardium (HM). The aim of this study was to test the hypothesis that myocardial contrast echocardiography (MCE), because of its better spatial and temporal resolution, would be superior to SPECT for the detection of HM. METHODS: Thirty-nine consecutive patients with symptomatic ischemic cardiomyopathy underwent rest and vasodilator SPECT and MCE. Of these, 23 survived to undergo assessment 3 months after revascularization for the recovery of left ventricular (LV) function (spontaneous recovery or dobutamine induced), which is the definition of HM. RESULTS: Of the 214 dysfunctional segments, 156 segments demonstrated HM in the 23 patients, of whom 16 showed significant improvement in LV function. Logistic regression analysis showed that both qualitative and quantitative MCE were independent predictors for the detection of HM (P < .0001 vs P = .06 for qualitative MCE vs qualitative SPECT, respectively, and P < .01 vs P = .25 for all quantitative myocardial contrast echocardiographic parameters vs quantitative SPECT, respectively). Using clinical and LV functional data, SPECT, and MCE for predicting the recovery of LV function, MCE was the only independent predictor (P = .03). CONCLUSION: MCE was superior to SPECT for the assessment of HM in ischemic cardiomyopathy.

Resting myocardial blood flow, coronary flow reserve, and contractile reserve in hibernating myocardium: implications for using resting myocardial contrast echocardiography vs. dobutamine echocardiography for the detection of hibernating myocardium.

AIMS: Controversy exists regarding the relative status of resting myocardial blood flow (MBF), coronary flow reserve (CFR), and contractile reserve (CR) in hibernating myocardium (HM). We hypothesized that CFR is more profoundly affected than resting MBF parameters in HM. Thus, resting MBF assessed by myocardial contrast echocardiography (MCE) will be more sensitive than CR elicited by dobutamine stress echocardiography (DSE) for the detection of HM. METHODS AND RESULTS: Accordingly 27 patients with ischaemic cardiomyopathy underwent resting MCE and DSE prior to revascularisation, of which 23 patients underwent follow-up echocardiography at 179 ± 66 days after revascularization. Qualitative and quantitative MCE [contrast intensity (A, dB)], MBF (represented by blood velocity ß, dB/s), and CFR (vasodilator ß/rest ß, ß reserve) were obtained. CR was obtained during DSE. Resting contrast intensity (7.2 ± 2.3 dB) and ß (0.67 ± 0.47 dB/s) were significantly (P < 0.005 and <0.01, respectively) reduced in HM vs. remote normal myocardium but significantly higher compared with non-viable segments (4.4 ± 2.3 dB and 0.43 ± 0.32 dB/s, respectively). However, CFR was significantly (0.82 ± 3.2 (P = 0.01)) lower in HM compared with normal (1.8 ± 1.02) but not significantly reduced when compared with non-viable myocardium (1.1 ± 3.3). Sensitivity for the detection of HM with qualitative and quantitative MCE were 82 and 87%, respectively, compared with 67% (P < 0.0001) by DSE with similar specificity of 55 and 67%, respectively, compared with 63% with DSE. CONCLUSION: Resting MBF but not CFR distinguished HM from non-viable myocardium. Resting MCE and not DSE was more accurate for the prediction of HM.

Pathological and physiological left ventricular hypertrophy: echocardiography for differentiation.

Distinguishing physiological left ventricular hypertrophy of an athlete's heart from that of pathological left ventricular (hypertrophic cardiomyopathy) can be difficult despite the advent of new imaging techniques. Nevertheless, the final diagnosis is of utmost importance as it will have a profound impact on an individual's life. A diagnosis of hypertrophic cardiomyopathy essentially excludes an individual from sport and strenuous exertion and necessitates the need for further tests and treatment, as well as the screening of family members. Hypertrophic cardiomyopathy remains the most common cause of a pathologically hypertrophied heart in young athletes, with a prevalence of one in 500. The issue of sudden death in athletes due to pathological left ventricular hypertrophy and hypertrophic cardiomyopathy has recently gained recognition owing to the death of several word class athletes during sporting participation. What compounds this further is the fact that a proportion of athletes fall into the 'grey zone' (ventricular wall thickness of 13-16 mm) where the increase in cardiac size overlaps with the phenotypic variation of hypertrophic cardiomyopathy - making echocardiographic differentiation of the two entities challenging. This review discusses the echocardiographic differentiation of the athlete's heart, including physiological left ventricular hypertrophy from pathological left ventricular hypertrophy. Although several of the cardiomyopathies cause pathological left ventricular hypertrophy, focus will be given to hypertrophic cardiomyopathy, for reasons mentioned above. Discussion will also focus on the newer and emerging echocardiographic techniques for this purpose. The term 'hypertrophic cardiomyopathy' is used to describe the nonobstuctive form of hypertrophic cardiomyopathy as this review article focuses on distinguishing the 'mild' form of hypertrophic cardiomyopathy from an athlete's heart. When the more severe obstructive form is being described, the term 'hypertrophic obstructive cardiomyopathy' is used.

Safety of contrast in stress echocardiography in stable patients and in patients with suspected acute coronary syndrome but negative 12-hour troponin.

Limited studies are available demonstrating the safety of contrast agents in patients undergoing stress echocardiography and none in patients with suspected acute coronary syndrome (ACS). Therefore, we sought to assess the safety profile of contrast agents in patients with stable chest pain and in those with suspected ACS (nondiagnostic electrocardiogram and negative initial 12-hour cardiac troponin test results). During a 4-year period, 3,704 patients underwent stress echocardiography (exercise or dobutamine), of whom, 929 (25%) had suspected ACS. Contrast agents (SonoVue 46%, Luminity 54%) were used in 1,150 patients (31%). No patients died with or without contrast administration. No nonfatal acute myocardial infarction occurred in patients administered contrast agents compared with 3 cases of acute myocardial infarction in the noncontrast group (p = 0.24). Two cases of sustained ventricular tachycardia developed, one in each group (p = 0.98). Compared with those who did not receive contrast, patients in both the stable chest pain and the suspected ACS groups had a greater burden of cardiovascular risk factors. The left ventricular function at rest was significantly worse in the patients who received contrast than in those who did not in the suspected ACS group. Also, a greater ischemic burden was present in those receiving contrast than in those not receiving it in both the stable chest pain and the suspected ACS groups. In conclusion, despite the presence of greater risk features compared with patients undergoing unenhanced stress echocardiography, the administration of ultrasound contrast agents (SonoVue and Luminity) in those with stable chest pain and those with suspected ACS was not associated with excess adverse events.

Contrast echocardiography: an update.

Despite the advent of tissue harmonic imaging, echocardiography fails to produce diagnostically useful images in a significant proportion of patients. This often leads to inaccurate assessment of left ventricular function, necessitating the use of other, more expensive and laborious imaging techniques, purely for diagnostic purposes. This has facilitated the development of microbubbles, which together with ultrasound, produce opacification of the left ventricular cavity, thus enabling clear visualization and accurate quantification of left ventricular function. Contrast agents have also facilitated the development of myocardial contrast echocardiography. This allows assessment of cardiac anatomy, function, and perfusion, all in one sitting, by the bedside. Contrast ultrasound imaging also has now been applied to newer techniques (eg, real-time three-dimensional echocardiography) and is also showing promise in other cardiovascular scans (eg, carotid ultrasound for intima-media thickness). Thus, contrast agents play a pivotal role in noninvasive cardiovascular imaging and its use worldwide is likely to increase.