Although we often think of syncope caused by PE in the setting of right ventricular failure and shock, less serious PE can also cause syncope by triggering a vaso-vagal reflex as supported by several case reports (1). Further supporting the potential role of neurogenic cause of syncope in at least some cases of PE is a study demonstrating that patients with syncope as a presenting symptom of PE did not show a more serious clinical picture (e.g. shock) than those without syncope (1). In another study of the clinical presentation of acute PE, EKG signs of acute right ventricle overload was found in only 25% of patients with syncope (2). So we shouldn’t rule out PE as cause of syncope just because signs of hemodynamic compromise are absent.
1. Castelli R, Tarsia P, Tantardini G et al. Syncope in patients with pulmonary embolism: comparison between patients with syncope as the presenting symptom of pulmonary embolism and patients with pulmonary embolism without syncope. Vascular Medicine 2003;8:257-261.
2. Miniati M, Cenci, Monti S, et al. Clinical presentation of acute pulmonary embolism: survey of 800 cases. PloS One 2012;7:e30891.
Although marijuana is often not considered to have serious cardiovascular effects, in animal studies THC, the active ingredient in cannabis, has been found to affect cardiovascular activity through a number of mechanisms, including inhibition of adrenal catecholamine secretion and modulation of cardiac vagal tone through inhibition of norepinephrine release from sympathetic neurons (1). There have also been reports of temporal association between marijuana use and acute coronary syndrome, cardiac arrhythmias, cerebrovascular events, including TIA’s, strokes, and cerebral vasospasm, as well as peripheral vascular events, including arteritis, Raynaud’s phenomenon, and digital necrosis (2). In a recent comprehensive case series, about 2.0 % of all cannabis-associated adverse events were reported cardiovascular in nature, with 25% resulting in death (2). However, it is often difficult to determine the relative contribution of marijuana and other concurrent conditions or substances (e.g. alcohol and tobacco) when cardiovascular complications occur. More research in this area is needed.
1. Szabo B, Nordheim U, Niederhoffer N. Effects of cannabinoids on sympathetic and parasympathetic neuroeffector transmission in the rabbit heart. J Pharmacol ExpTher 2001; 297:819-826.
2. Jouanjus E, Lapeyre-Mestre M, Micallef J, et al. Cannabis use: signal of increasing risk of serious cardiovascular disorders. J Am Heart Assoc 2014; 3:e000638
Contributed by Pierre Ankomah, MD, Boston, MA
CF is caused by gene mutations that result in deficient or dysfunctional transmembrane conductance regulator (CFTR) protein, an anion channel that is normally present in the epithelial membrane. Two FDA- approved drugs may provide new options for at least some CF patients. Ivacaftor (Kalydeco) is a CFTR protein potentiator that increases the probability that the CFTR channels are open in vitro and improves clinical outcomes in patients ≥12 years of age with at least one copy of G551D mutation, present in ~5% of CF patients (1).
Orkambi is a combination of ivacaftor and lumacaftor – a drug that prevents intracellular destruction of CFTR –for patients with the Phe508del CFTR mutation, present in ~50% of CF patients. Its use has been associated with fewer pulmonary exacerbations and hospitalization in patients (≥ 6 years of age) homozygous for this gene (2). Ivacaftor and Orkambi are priced at over $300,000/year and $295,000/year, respectively (http://www.nytimes.com/2015/07/03/business/orkambi-a-new-cystic-fibrosis-drug-wins-fda-approval.html?_r=0).
1. Ramsey BW, Davies J, McElvaney NG, et al. A CFTR Potentiator in patients with cystic fibrosis and the G551D mutation. N Engl J Med 2011;365:1663-1672.
2. Wainwright CE, Elborn JS, Ramsey BW, et al. Lumacaftor-ivacaftor in patients with cystic fibrosis homozygous for Phe508del CFTR. N Engl J Med 2015;373:220-231.
Contributed by Cynthia M. Cooper, MD, Boston, MA
CSA-CSR is characterized by a crescendo-decrescendo pattern of 20-30 second hyperventilation followed by 10- 40 second hypopneas or apneas during exercise, wakefulness or stages 1 and 2 non-rapid eye movement sleep (1,2). CSA-CSR is associated with elevated pulmonary capillary wedge pressure, ventricular dilatation, atrial fibrillation, and increased central and peripheral chemosensitivity to arterial C02 levels (1).
In contrast to obstructive sleep apnea whose detrimental impact is widely accepted, CSA-CSA has not consistently been shown to be associated with higher mortality rates, with some even arguing for its beneficial effects in HF by providing intrinsic positive end-expiratory pressure (PEEP), augmented stroke volume, avoidance of hypercapnic acidosis, attenuated sympathetic activity, bronchodilation and cyclic respiratory muscle rest, akin to those seen with episodic CPAP (2). This is an interesting way of looking at CSA-CSR, underscoring the importance of addressing the underlying problem (e.g. HF) rather than the symptoms alone.
1. Rosen D, Roux FJ, Shah N. Sleep and breathing in congestive heart failure. Clin Chest Med 2014, 35: 521–534. https://www.ncbi.nlm.nih.gov/pubmed/25156768
2. Naughton MT. Cheyne-Stokes respiration: friend or foe. Thorax 2012;67:357-360. http://thorax.bmj.com/content/thoraxjnl/67/4/357.full.pdf
Ventricular conduction defects associated with a widened QRS complex—specifically, complete and incomplete bundle branch blocks—may artificially elongate the QT interval without reflecting an actual increase in myocardial repolarization time (1). In complete bundle branch block, the widened QRS complex may elongate the QTc interval by as much as 16% while having no effect on the JT index, defined as JT interval x (heart rate+ 100)/518), where an index >112ms is considered to be prolonged (2). Calculation of the JT index has been suggested for patients with incomplete bundle branch block, as well (2).
Put simply, in patients with ventricular conduction defects associated with a widened QRS complex, the JT index appears to be superior to the QTc interval for assessment of repolarization time.
1. Salik J, Muskin P. Consideration of the JT interval rather than the QT interval. Psychosomatics 2013; 54(5): 502.
2. Zhou SH, Wong S, Rautaharju PM, et al. Should the JT rather than the QT be used to detect prolongation of ventricular repolarization? An assessment in normal conduction and in ventricular conduction defects. J Electrocardiology 1992; 25 (Suppl): 131-6.
Contributed by Jonathan Salik, MD, Boston, MA
The short answer is “yes” when deep veins, such as brachial, axillary or subclavian are involved; cephalic and basilic veins are superficial. Although some have suggested that isolated brachial vein thrombosis may be considered at low risk of complication, this assumption has not been corroborated by objective research (1).
There are no randomized trials of AC therapy in patients with upper extremity deep vein thrombosis (UEDVT). However, the American College of Chest Physicians has recommended a 3-month course of AC therapy similar to that of leg DVT for several reasons (1,2):
- UEDVT has generally been reported to have complications and consequences comparable to that of leg DVT
- Several small cohort studies suggest lower rates of recurrent DVT, PE, and bleeding when UEDVT is treated similar to leg DVT
- Known demonstrated benefit of AC therapy in leg DVT
In addition, post-thrombotic syndrome is relatively common (~1 in 5) among patients with UEDVT (3)
1. Hingorani A, Ascher E, Marks N, et al. Morbidity and mortality associated with brachial vein thrombosis. Ann Vasc Surg 2006; 20:297-299. https://www.ncbi.nlm.nih.gov/pubmed/16779509
2. Kearon C, Akl EA, Comerato AJ, et al. Antithrombotic therapy for VTE disease: American College of Chest Physicians Antithrombotic Therapy and Prevention of Thrombosis Panel. Antithrombotic therapy for VTE disease: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012;141(suppl):419S-494S. https://www.ncbi.nlm.nih.gov/pubmed/22315268
3. Maynard G. Upper extremity deep vein thrombosis:A call to arms. JAMA Intern Med 2014;696-698. https://www.ncbi.nlm.nih.gov/pubmed/24638129