An 82-year-old woman presented to the emergency department with chest pain after sustaining a transient ischemic attack 1 week prior to presentation. Electrocardiography revealed ST-segment elevation in leads I, II, aVF, and V3 through V6. Coronary angiography demonstrated nearly normal coronaries but left ventriculography showed apical akinesis and basal hyperkinesis. One month later her follow-up echocardiography showed no wall motion abnormalities. Several reports of tako-tsubo syndrome or transient left ventricular apical ballooning have been described, especially in Japan. We present a case with the typical features of the syndrome after a cerebrovascular accident.

Background Obesity and hypertension are two risk factors of left ventricular hypertrophy (LVH) in adults. We aimed to examine the impacts of body weight and blood pressure (BP) from childhood on adult LV geometric remodeling. Methods The study cohort consisted of 1256 adults aged 27–42 years who had 2–10 measurements of body mass index (BMI) and BP from childhood in 1987 to adulthood in 2010. We calculated the cumulative and incremental values of BMI and BP from childhood to adulthood. In adulthood, four LV geometric patterns were defined based on the values of left ventricular mass index (g/m2.7) and relative wall thickness: normal geometry, concentric remodeling (CR), eccentric hypertrophy (EH) and concentric hypertrophy (CH). Results The prevalence of abnormal LV geometric patterns in adults was 26.4% for CR, 2.0% for EH and 2.5% for CH. For childhood values, systolic BP (Odds Ratio [OR] = 1.26, 95% confidence interval [CI] = 1.08–1.47) but not BMI (OR = 1.06, 95%CI = 0.93-1.18) was associated with adult CR, whereas BMI (OR = 3.53, 95%CI = 2.09–5.98) but not systolic BP (OR = 1.04, 95%CI = 0.65–1.66) was associated with adult EH. Both childhood BMI (OR = 2.69, 95%CI = 1.77–4.09) and systolic BP (OR = 1.64, 95%CI = 1.07–2.51) were independently associated with adult CH. For adulthood, cumulative and incremental values, BMI and systolic BP were independently associated with adult CR, EH and CH. Conclusion Excessive body weight and elevated BP from childhood have independent influences on the development of adult LV geometric remodeling.

Background: Resistant hypertension (RH) is defined as blood pressure (BP) that remains elevated (>140/90mmHg) despite being treated with an antihypertensive regimen of 3 or more medications from different classes, including a long-acting calcium channel blocker, an angiotensin converting enzyme inhibitor or angiotension receptor blocker and a diuretic. The prevalence of RH in South Africa is currently unknown, however, clinical reports suggest that it is not rare. Patients with RH are significantly predisposed to cardiovascular (CV) diseases compared to patients with controlled BP. Consequences of RH include left ventricular hypertrophy, heart failure, ischaemic heart disease, chronic kidney disease leading to end-stage renal disease, stroke, vascular dementia, CV death and peripheral arterial disease. A proportion of patients with RH who never achieve BP control despite maximal medical treatment, represent a potentially novel and distinctive phenotype which is different from RH patients whose BP canbe controlled. Recognising and categorising such patients becomes the initial and crucial step in stratifying phenotypes and defining mechanisms of treatment resistance. Objectives: The aim of this study was to identify patients with resistant uncontrolled hypertension (RUH) and compare phenotypes in these patients to resistant controlled hypertensives (RCH). Methods: We enrolled 50 patients from the Groote Schuur Hospital Hypertension Clinic: a teriary referral hospital for RH. Patients on 4 or more antihypertensive medication including a diuretic, with BP< 140/90mmHg were considered RCH, and those with BP ≥ 140/90 considered RUH. Assessments included clinical examination, electrocardiography, echocardiography, applanation tonometry, serum biomarkers and cardiovascular magnetic resonance (CMR - which included biventricular volumes and function, myocardial strain, tissue characteristics and late gadolinium enhancement - LGE). Results: Thirty were diagnosed with RUH and twenty with RCH. Patients with RUH were more likely to have a longer duration since diagnosis of hypertension (10.5±10.7 vs. 3.6±3.4, p=0.02) and more likely to be on treatment that included an ACE-inhibitor (90% vs. 58%, p=0.01). As expected, patients with RUH had significantly higher systolic BP (155.6±21.6 vs. 137.8±16.5 mmHg, p< 0.001), diastolic BP (88.4±14.5 vs. 77.5±13.6 mmHg, p= 0.03), mean arterial BP (115.4±17.2 vs 101±15.3 mmHg, p= 0.004) and pulse pressure (67.3±14.2 vs. 60.1±12.4 mmHg, p=0.001). Further, RUH patients had significantly lower large artery elasticity (12.5±4 vs 14.7±3.8ml/mmHgx100, p=0.08) and lower small artery elasticity (4.1±2.1 vs. 6.9±3.6ml/mmHgx100, p< 0.001). RUH patients also had a higher systemic vascular resistance (1754±418.4 vs. 1363±371.5dyneXsecXcm-5, p=0.002). On CMR, RUH patients had lower right ventricular (RV) end-systolic and end-diastolic volumes (p=0.02), as well as higher indexed left ventricular mass (LVMI) (61.6±17.6 vs 52.9±13.9 g/m2 , p= 0.06). There were no differences in native T1, extracellular volume quantification and LGE volume fraction between RUH and RCH patients. Conclusions: Patients with RUH have a greater involvement and more severe CV phenotype, that is likely to result in increased CV morbidity and mortality, including greater target end organ damage as a result of vascular adaptations and concentric remodeling.

Left ventricular diastolic dysfunction (LVDD) is any abnormality in the filling of the left ventricle (LV).  Despite the prevalence of this disease, it remains difficult to diagnose, mainly due to inherent compensatory mechanisms and a limited physical understanding of the filling process.  LV filling can be non-invasively imaged using color m-mode echocardiography which provides a spatio-temporal map of inflow velocity.  These filling patterns, or waves, are conventionally used to qualitatively assess the filling pattern, however, this work aims to physically quantify the filling waves to improve understanding of diastole and develop robust, reliable, and quantitative parameters. This work reveals that LV filling waves in a normal ventricle act as dispersive waves and not only propagate along the length of the LV but also spread and disperse in the direction of the apex.  In certain diseased ventricles, this dispersion is limited due to changes in LV geometry and wall motion.  This improved understanding could aid LVDD diagnostics not only for determining health and disease, but also for distinguishing between progressing disease states. This work also identifies a limitation in a current LVDD parameter, intra ventricular pressure difference (IVPD), and presents a new methodology to address this limitation.  This methodology is also capable of synthesizing velocity information from a series of heartbeats to generating one representative heartbeat, addressing inaccuracies due to beat-to-beat variations.  This single beat gives a comprehensive picture of that specific patient's filling pattern.  Together, these methods improve the clinical utility of IVPD, making it more robust and limiting the chance for a misdiagnosis. / Master of Science

Cardiac arrest due to air embolism is an infrequent complication. Air embolism can be associated with procedures like endoscopic retrograde cholangiopancreatography, endoscopic variceal ligation, operative hysteroscopy, laparoscopic surgery, pacemaker placement, cardiac ablation, fiberoptic bronchoscopy, and decompression sickness. In rare cases, air embolus can be a catastrophic complication of computed tomography (CT) guided lung biopsy, which can lead to cardiac arrest. We present a case of a 67-year-old male chronic smoker with a left lower lobe pulmonary nodule who had a cardiac arrest due to air embolism as a consequence of CT guided biopsy of the pulmonary nodule found on a CT scan of the chest. He was successfully resuscitated and intubated for mechanical ventilation. He was managed conservatively and discharged home in a stable condition.

The Left Ventricular Assist Device (LVAD) is a rotary mechanical pump that is implanted in patients with congestive heart failure to help the left ventricle in pumping blood in the circulatory system. The rotary type pumps are controlled by varying the pump motor current to adjust the amount of blood flowing through the LVAD. One important challenge in using such a device is the desire to provide the patient with as close to a normal lifestyle as possible until a donor heart becomes available. The development of an appropriate feedback controller that is capable of automatically adjusting the pump current is therefore a crucial step in meeting this challenge. In addition to being able to adapt to changes in the patient's daily activities, the controller must be able to prevent the occurrence of excessive pumping of blood from the left ventricle (a phenomenon known as ventricular suction) that may cause collapse of the left ventricle and damage to the heart muscle and tissues. In this dissertation, we present a new suction detection system that can precisely classify pump flow patterns, based on a Lagrangian Support Vector Machine (LSVM) model that combines six suction indices extracted from the pump flow signal to make a decision about whether the pump is not in suction, approaching suction, or in suction. The proposed method has been tested using in vivo experimental data based on two different LVAD pumps. The results show that the system can produce superior performance in terms of classification accuracy, stability, learning speed, iv and good robustness compared to three other existing suction detection methods and the original SVM-based algorithm. The ability of the proposed algorithm to detect suction provides a reliable platform for the development of a feedback control system to control the current of the pump (input variable) while at the same time ensuring that suction is avoided. Based on the proposed suction detector, a new control system for the rotary LVAD was developed to automatically regulate the pump current of the device to avoid ventricular suction. The control system consists of an LSVM suction detector and a feedback controller. The LSVM suction detector is activated first so as to correctly classify the pump status as No Suction (NS) or Suction (S). When the detection is “No Suction”, the feedback controller is activated so as to automatically adjust the pump current in order that the blood flow requirements of the patient’s body at different physiological states are met according to the patient’s activity level. When the detection is “Suction”, the pump current is immediately decreased in order to drive the pump back to a normal No Suction operating condition. The performance of the control system was tested in simulations over a wide range of physiological conditions.

The aim of this retrospective study was to investigate whether there would be an association between periodontal disease parameters and positive bacterial findings at the driveline of patients with a left ventricular assist device (LVAD). Patients with an LVAD, who underwent a full oral and microbiological examination between 2016 and 2018, were included. During oral examination, periodontitis severity (stage and grade) and the periodontal inflamed surface area (PISA) were evaluated. A microbiological analysis was performed from swabs of the driveline, whereby different bacterial species were cultivated and analyzed. A total of 73 patients were included in the current study. The majority of participants (80.8%) had at least one positive bacterial finding during the study period. Most patients had a periodontitis stage of III-IV (80.9%). The determined PISA of the total group was 284.78 ± 352.29 mm2. No associations were found between the periodontal disease parameters and the bacterial findings in general, the bacterial findings on the day of oral examination or the bacterial findings 12 months prior to/after the oral examination (p > 0.05). Periodontitis is not associated with cultivated microbiological findings at the driveline of patients with an LVAD and thus appears not to be a risk indicator for driveline colonization. Nevertheless, the high periodontal burden in LVAD patients underlines the need for their improved periodontal care.

The rotary Left Ventricular Assist Device (LVAD) is a mechanical pump surgically implanted in patients with end-stage congestive heart failure to help maintain the flow of blood from the sick heart. The rotary type pumps are controlled by varying the impeller speed to control the amount of blood flowing through the LVAD. One important challenge in using these devices is to prevent the occurrence of excessive pumping of blood from the left ventricle (known as suction) that may cause it to collapse due to the high pump speed. The development of a proper feedback controller for the pump speed is therefore crucial to meet this challenge. In this thesis, some theoretical and practical issues related to the development of such a controller are discussed. First, a basic nonlinear, time-varying cardiovascular-LVAD circuit model that will be used to develop the controller is reviewed. Using this model, a suction index is tested to detect suction. Finally we propose a feedback controller that uses the pump flow signal to regulate the pump speed based on the suction index and an associated threshold. The objective of this controller is to continuously update the pump speed to adapt to the physiological changes of the patient while at the same time avoiding suction. Simulation results are presented under different conditions of the patient activities. Robustness of the controller to measurement noise is also discussed.

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