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Supraventricular rhythms
Published in Andrew R Houghton, Making Sense of the ECG, 2019
As the name suggests, sick sinus syndrome is a collection of impulse generation and conduction problems related to dysfunction of the sinus node. Any, or all, of the following problems may be seen in a patient with the syndrome: Sinus bradycardiaSinus tachycardiaSinus arrestSA block
Cardiovascular changes with aging
Published in Wilbert S. Aronow, Jerome L. Fleg, Michael W. Rich, Tresch and Aronow’s Cardiovascular Disease in the Elderly, 2019
The cardiac conduction system undergoes multiple changes with age that affect its electrical properties and, when exaggerated, cause clinical disease. A generalized increase in elastic and collagenous tissue commonly occurs. Fat accumulates around the sinoatrial node, sometimes creating partial or complete separation of the node from the atrial tissue. In extreme cases, this may contribute to the development of sick sinus syndrome. A pronounced decline in the number of pacemaker cells generally occurs after age 60; by age 75, less than 10% of the number seen in young adults remain. A variable degree of calcification of the left side of the cardiac skeleton, which includes the aortic and mitral annuli, the central fibrous body, and the summit of the interventricular system, is observed. Because of their proximity to these structures, the atrioventricular (AV) node, AV bifurcation, and proximal left and right bundle branches may be damaged or destroyed by this process, resulting in AV or intraventricular block.
Pharmacological treatment of bipolar affective disorder in old age
Published in Stephen Curran, John P Wattis, Practical Management of Affective Disorders in Older People, 2018
Polydipsia, polyuria, tremor, dry mouth and subjective memory impairment are the most frequent side-effects. In the longer term, hypothyroidism may occur and this may necessitate treatment with thyroxine. Nephrotoxicity is another long-term complication. A small proportion of patients develop irreversible reduction in urinary concentrating capacity after long-term treatment19 and renal changes may include interstitial fibrosis and tubular atrophy. There are reports of psoriasis being exacerbated. The sick sinus syndrome may occur in older adults with compromised sinus node function. In a cross-sectional study, Roose et al.20 reported that more than half of older patients treated with maintenance lithium had electrocardiogram abnormalities such as conduction defects.
Re-implantation after extraction of a cardiac implantable electronic device
Published in Acta Cardiologica, 2020
Koen De Schouwer, Ruben Vanhove, Christophe Garweg, Gabor Voros, Peter Haemers, Joris Ector, Rik Willems
We included both lead removals and lead extractions. According to the Heart Rhythm Society, the definition of an extraction of CIED leads is the removal of any lead implanted for more than one year, or a lead regardless of duration of implant requiring the assistance of specialised equipment that is not included as part of the typical implant package, and/or removal of a lead from a route other than via the implant vein [10]. Lead infections were defined as either localised or generalised. Localised infection was defined as an infection limited to the device pocket. Generalised infection was defined as endovascular infection with systemic inflammation (sepsis or endocarditis). We categorised indications for implantation of a PM as either symptomatic or possibly lifesaving. We defined sick sinus syndrome (SSS), atrial fibrillation with slow ventricular response and neurocardiogenic syncope as symptomatic indications for a PM. 2nd and 3rd degree AV blocks were defined as possibly lifesaving indications. For ICDs, we made a distinction between secondary prevention after cardiac arrest vs. any primary prevention indication for implantation of the defibrillator.
Disease modeling of cardiac arrhythmias using human induced pluripotent stem cells
Published in Expert Opinion on Biological Therapy, 2019
Wenbin Liang, Lilit Gasparyan, Wael AlQarawi, Darryl R. Davis
Impaired impulse generation in the sinoatrial node, or Sick Sinus Syndrome, manifests clinically as pauses between beats, abnormally slow heart rates or the inability to increase heart rate in response to exertional needs [61]. Sick Sinus Syndrome has a prevalence of ~535 cases per million in the general population but occurs in 1 of every 600 adults older than 65 years [62] and is responsible for almost half the electronic pacemaker implantations in Canada and the United States. Atrioventricular block refers to a partial or complete block of impulse conduction from the atria to the ventricles via the atrioventricular node and/or His-Purkinje system [62]. Although rare in the general population, atrioventricular block is more frequent in patients with diabetes (1.1%) [63] or hypertension (0.6%) [62] and, given the risk of mechanical standstill, evaluation for implantable pacemaker support is required.
The impact of chronic kidney disease on medication choice and pharmacologic management in patients with heart failure
Published in Expert Review of Clinical Pharmacology, 2018
Syed Raza Shah, David E Winchester
Ivabradine is one of the newer drugs used in patients with HF. These drugs act by inhibiting the sinoatrial node, hence reducing heart rate without lowering the blood pressure [88]. Recent trials have shown a significant reduction in hospitalization rates in patients using ivabradine (in addition to conventional treatment) compared to conventional treatment alone [89]. However, the cardiovascular mortality is not significantly decreased [89]. Besides, ivabradine is metabolized by the cytochrome P450 system; hence, it should be avoided in patients with hepatic impairment [90]. Also, patients with sick sinus syndrome or a heart block should not get this medication [90]. Hence, patients with stable systolic HF already on maximal medication therapy, adding ivabradine may reduce the number of hospitalizations related to HF but it does not reduce cardiovascular mortality. In addition, many patients will not tolerate the drug and will stop taking it. Patients should also be monitored for the development of bradycardia.