Daniel Vanhercke

Eight years of left ventricle pacing due to inadvertent malposition of a transvenous pacemaker lead in the left ventricle

The inadvertent malposition of a pacemaker lead in the left ventricle is a rare and underdiagnosed pacemaker complication. A 78-year-old woman was admitted to our Emergency Department for progressive dyspnea, 8 years after transvenous pacemaker implantation. Routine 12-lead electrocardiography revealed a right bundle branch block on the paced beats, and lateral chest X-ray showed posterior deflection of the pacemaker lead, suggesting a pacemaker electrode in the left ventricle. Echocardiography confirmed that the pacing lead had migrated through the foramen ovale into the left ventricle. After review of the literature and taking into account the age and emboligenic-free history of the patient under platelet therapy, we decided to postpone the surgical removal of the malpositioned lead in the left ventricle until the need arose for cardiac surgery for additional reasons, such as valve and/or coronary illness. The general therapeutic strategy remained unchanged due to the risk of bleeding complications with anticoagulation in the patient. This case illustrates the prominent role of echocardiography in the diagnosis of unusual cardiac events.

Experimental analysis of the hemodynamics in punctured vascular access grafts

The hemodynamics in the vascular access graft are influenced by the flow aspirated and injected through the two needles during hemodialysis. For the first time, the impact of needle flow on vascular access performance, measured in an in vitro set up, is reported. A vascular access model, consisting of a loop polytetrafluoroethylene graft sewn to a compliant artery and vein, simulated the patient. The extracorporeal circuit was connected to the model. Three mean access flow rates (QG; 500, 1,000, and 1,500 ml/min) and five roller pump flow rates (QR; 0, 200, 300, 400, and 500 ml/min) were studied. Mean, systolic, and diastolic pressure and according pressure drops were derived at 14 loci. Systolic, diastolic, and mean pressures drop along the graft decreased with increasing QR and decreasing QG. At QR = 500 ml/min and QG = 500 ml/min, the mean pressure drop over the graft was negative (–10 mm Hg), indicating a reversed pressure profile, originating at the puncture site of the venous needle. Mean pressure in the venous outlet segment was about 100 mm Hg compared with only 75 mm Hg without needle flow. The combination of a low QG (500 ml/min) and high QR (>300 ml/min) must be avoided because venous pressures can rise to 100 mm Hg and load the venous system. The results of this in vitro setup indicate that high QR (>400 ml/min) should be avoided at QG up to 1,000 ml/min; however, in vivo tests have to be performed to prove this thesis. This study demonstrates the need for a well-functioning vascular access (QG > 600 ml/min) to perform adequate dialysis and to avoid venous system loading.

Innervation of the atrioventricular and semi-lunar heart valves: a review.

Heart valves were historically considered passive structures that function through the haemodynamic forces created by the contraction and relaxation of the myocardium. However, research into valvular structures has revealed that heart valves are very complex, specialized structures that contain both smooth muscle cells and nerve fibres. This is particularly true for the atrioventricular valves, which are by far the most well studied to date. The various heart valves have been shown to contract independently during different moments of the heart cycle, suggesting that compensatory adaptation mechanisms exist to mediate the timing and efficacy of heart valve closure.These adaptations occur via different mechanisms, including neural mechanisms that influence the heart valves. Accumulating evidence continues to improve our understanding of the nerve fibres in the heart (adrenergic, cholinergic, etc.). Future studies will no doubt add to this exciting picture. Here, we review the current morphological knowledge of human and animal heart valve innervation, including discussions of the chordae tendineae and the papillary muscles, as well as the differences between the atrioventricular (AV) valves and the semi-lunar (SL) valves.

Prevalence, determinants, and prognostic significance of pulmonary hypertension in elderly patients admitted with acute decompensated heart failure: a report from the BIO-HF Registry

Pulmonary hypertension (PHT) is a predictor of mortality and morbidity in patients with chronic heart failure (HF). However, the prevalence, determinants, and prognostic significance of PHT in elderly patients admitted with acute decompensated HF are unclear.

Non-invasive assessment of hemodynamics in adolescents with arterial tonometry and Doppler ultrasound during a conventional stress test

Aiming to improve early diagnosis of people at cardiovascular risk, we are developing a custom set-up to allow an adequate hemodynamic analysis of heart function and arterial circulation properties, based on non-invasive acquisition of pressure (arterial tonometry) and flow (Doppler ultrasound techniques) waveforms. In an experimental setting 15 healthy volunteers were examined on a custom made supine bicycle. Able to record usable data throughout the bicycle test and automatically analyse derived hemodynamic parameters such as compliance, peripheral resistance, etc., we also applied the set-up in a real clinical environment. This research contributes to a more complete cardiovascular examination without significant additional discomfort for the patient or prolongation of the test protocol.

Feasibility of Combined Doppler–ECG Assessment of Internal Jugular Veins

A standardized combined Doppler-electrocardiography technique was developed for measurement of the triphasic waveform characteristics in the internal jugular vein. Flow velocities at the A, X, V and Y peaks, the RR interval and the PA and RX times were measured. From these the venous impedance index ([X-A]/X) and the ratios PA/RR and RX/RR were calculated. Six measurements were performed at three different locations by two ultrasonographers in 21 randomly selected pregnant and non-pregnant women. Statistical models proved the feasibility and reproducibility of this technique, with the highest concordance correlation coefficients in the right distal internal vein. Bootstrapping revealed that repeating the measurements more than four times would not significantly enhance the precision of the estimated mean. Concordance correlation coefficients for the venous impedance index, PA time and PA/RR ratio were >0.63 for all three locations, proving their possible use in ongoing and future studies, analogous to previous studies in kidney and liver.

B1. Feasibility of combined Doppler-ECG assessment of internal jugular veins.

Abstract Introduction: Studying the venous compartment may add valuable information on background mechanisms and (patho)physiology of the cardiovascular system in normal pregnancies and pregnancies complicated by preeclampsia. Every component of the venous pulse wave is reflecting a specific stage of the cardiac cycle in the right atrium, and can be recognized in the neck veins, the hepatic and the renal veins. Previous studies have demonstrated the repeatability and reproducibility of venous Doppler sonography and venous pulse transit time in renal interlobar and hepatic veins. In this study we focus on the Doppler assessment of the triphasic pulse wave in the internal jugular vein, the easily accessible vein between brain and right atrium of the heart. Methods: A standardized combined Doppler-ECG technique was used for measurement of the triphasic waveform characteristics in the internal jugular vein. Similar to reported studies in renal interlobar and hepatic veins, the following parameters were measured: flow velocities at ‘‘A’’-, ‘‘X’’-, ‘‘V’’- and ‘‘Y’’-peak, the venous impedance index ([X – A]/X) and the time relation between the ‘‘P’’ (ECG) & ‘‘A’’ and the ‘‘R’’ (ECG) & ‘‘X’’. The examination was performed at three different locations: (1) the right proximal, (2) the right distal and (3) the left proximal internal jugular vein. At each location, six measurements were performed by two ultrasonographers in 23 randomly selected women (almost all pregnant). For the evaluation of inter and intra rater agreement a mixed model was used (Barnhart 2007). A bootstrap experiment was used to evaluate the stability of the averaged values. To illustrate this combined Doppler-ECG assessment of the internal jugular vein, a three-minute English spoken video sequence has been recorded. Results: The Concordance Correlation Coefficient was >0.6 for all the parameters at the three locations, with exception of the inter rater agreement of the ‘‘X’’-, ‘‘V’’- and ‘‘Y’’ peak in the right and left proximal internal jugular vein and the intra rater agreement of the ‘‘X’’-peak in the left proximal internal jugular vein of one of both raters (Table 1). The bootstrap experiment showed that four measurements are sufficient to obtain stable values (no further decrease of the standard deviation by additional measurements). Conclusion: Combined Doppler-ECG assessment is a simple, safe, easily accessible and noninvasive bed-side technique to measure the venous waveform characteristics in the internal jugular vein. Statistical models showed for most parameters an acceptable inter and intra rater agreement for averaged 4-point values at all three locations.

Assessment of the Tilting Properties of the Human Mitral Valve during Three Main Phases of the Heart Cycle: An Echocardiographic Study

Rationale and Objectives: In experimental models of the left heart, the mitral valve (MV) is commonly implanted perpendicular to a central axis of the apex/MV. To adapt this to a more correct anatomical model, as well as for further studies of the left ventricle, we created a database of implantation angles of the MV and annulus during three main phases of the heart cycle, based on standard cardiac ultrasound measurements. Materials and Methods: Twenty‐eight patients were studied with the standard cardiac ultrasound equipment. From the apical echo window, an anteroposterior (AP) plane and a perpendicular commisure‐commisure (CC) plane were generated during three critical moments in the heart cycle: systole (S); diastole early filling (E); and diastole late filling (A). In both planes, the angles between the annular plane and each mitral leaflet, as well as the angle between a theoretical longitudinal axis through the apex and center of the MV orifice and the mitral annulus plane, were measured with a custom‐made application of Matlab R14. Results: We observed an inclination of the angle mitral annulus/central left ventricle axis, with its lowest point in the direction of the aortic valve (AP plane) of 85°± 7° in systole (S), 88°± 8° in early diastole (E), and 88°± 7° in late diastole (A). In the CC plane, we observed an almost horizontal implantation of 91°± 5° in systole (S), 91°± 8° in early diastole (E), and 91°± 7° in late diastole (A).

Hemolab: a custom built diagnostic tool for non-invasive, synchronized recording and real-time monitoring of a Doppler spectrogram, an electrocardiogram and arterial tonometry

In clinical diagnostic practice, various medical devices are designed for specific investigations and have no margin for adding other input signals or profound post-processing. Although information obtained from these signals separately is useful, using them in a combined way allows for a more profound analysis of the cardiovascular system. Our goal was to build an affordable, compact and easy-to-use diagnostic tool enabling a synchronized acquisition of arterial pressure and flow waveforms, combined with an electrocardiogram (ecg), all in non-invasive way and to be used in a routine diagnostic setting without prolonging testing protocols or adding discomfort to the patient. The combination of the beat-to-beat pressure and velocity information allows to calculate hemodynamic parameters that can quantify mechanical characteristics of the arterial system such as compliance and resistance. In this study, we used an applanation tonometer, an ecg recorder and an ultrasound device. We built a handy diagnostic tool called Hemolab that can combine the output of several stand-alone medical monitoring devices. A synchronized acquisition of a Doppler spectrogram, an electrocardiogram and a continuous pressure signal could already be acquired non-invasively, monitored in real-time and saved for later processing. This work contributes to obtain diagnostic information from non-invasive hemodynamical parameter analysis.

Images in cardiology: coincidental diagnosis of a myxoma during abdominal ultrasound.

An 87-year-old woman was admitted to the hospital because of rib fractures. She had fallen three times during the last weeks, sometimes with loss of consciousness. On physical examination we suspected bladder retention. An abdominal ultrasound confirmed urinary retention. While scanning the upper abdomen the echographist noticed a mass in the left atrium (Fig. 1). Transthoracic echocardiography showed aortic sclerosis and a mild insufficiency of the aortic valve, a good left ventricular function and a semi-mobile mass, attached to the interatrial septum. Transoesophageal echocardiography confirmed a left atrial tumour arising from the interatrial septum at the foramen ovale.