Chukwudi Obiagwu

Role of Vasodilator Testing in Pulmonary Hypertension.

Pulmonary hypertension is clinically defined by a mean pulmonary artery (PA) pressure of 25mm Hg or more at rest, as measured by right heart catheterization. To identify patients who are likely to have a beneficial response to calcium channel blockers (CCBs) and therefore a better prognosis, acute vasodilator testing should be performed in patients in certain subsets of pulmonary arterial hypertension (PAH). A near normalization of pulmonary hemodynamics is needed before patients can be considered for therapy with CCBs. Intravenous adenosine, intravenous epoprostenol, inhaled nitric oxide, or inhaled iloprost are the standard agents used for vasoreactivity testing in patients with idiopathic PAH. In this review we describe the various aspects of vasodilator testing including the rationale, pathophysiology and agents used in the procedure.

Nanomedicine in coronary artery disease

Nanomedicine is one of the most promising therapeutic modalities researchers are working on. It involves development of drugs and devices that work at the nanoscale (10–9 m). Coronary artery disease (CAD) is responsible for more than a third of all deaths in age group >35 years. With such a huge burden of mortality, CAD is one of the diseases where nanomedicine is being employed for preventive and therapeutic interventions. Nanomedicine can effectively deliver focused drug payload at sites of local plaque formation. Non-invasive strategies include thwarting angiogenesis, intra-arterial thrombosis and local inflammation. Invasive strategies following percutaneous coronary intervention (PCI) include anti-restenosis and healing enhancement. However, before practical application becomes widespread, many challenges need to be dealt with. These include manufacturing at the nanoscale, direct nanomaterial cellular toxicity and visualization.

Acute pulmonary edema secondary to hyperbaric oxygen therapy.

Hyperbaric oxygen therapy (HBOT) has been shown to be effective in the treatment of diabetic ulcers, air embolism, carbon monoxide poisoning and gas gangrene with minimal adverse effects. Very few cases of HBOT causing acute pulmonary edema (PE) has been described; with a study on dogs suggesting that a complication of this therapy could be PE. We describe the case of an 80-year-old man with a history of stable systolic heart failure and diabetes mellitus presenting with acute PE following treatment with HBOT for diabetic foot.

Severe Pulmonary Hypertension Due to Adult-Onset Still’s Disease

A 29-year-old female with adult-onset Still’s disease (AOSD) presented with progressive shortness of breath both on rest and on exertion, increased abdominal girth, and swelling in both legs. She was on oral prednisone and was recently started on canakinumab (interleukin-1 antagonist) for joint pain and rash of AOSD. Echocardiogram showed severely dilated right ventricle, dilated pulmonary artery, moderately reduced right ventricular systolic function, but with normal left ventricular systolic function. Computed tomography with contrast ruled out pulmonary embolism. Blood tests ruled out other rheumatologic diseases. The patient was diagnosed with right-sided heart failure likely secondary to AOSD. Right heart catheterization was needed but could not be performed because of severely dilated pulmonary artery. The patient was transferred to a higher center for further management and possible cardiopulmonary transplant.

Novel Oral Anticoagulants in Atrial Fibrillation: Update on Apixaban.

Almost 800,000 new or recurrent strokes occur every year. Atrial fibrillation, the most common cardiac arrhythmia, is a major risk factor for stroke, accounting for 15-20% of ischemic strokes. Apixaban is a direct inhibitor of Factor Xa that was approved in December 2012 by the US Food and Drug Administration (FDA) for the prevention of stroke in patients with non-valvular atrial fibrillation. It is part of a family of novel oral anticoagulants (NOACs) which has advantage over warfarin of less dosing variability, rapid onset of action and no INR monitoring required. Apixaban showed superiority to warfarin in both primary efficacy and primary safety outcomes by simultaneously showing both significantly lower rates of strokes and systemic embolism and a reduced risk of major clinical bleeding in clinical trials. Warfarin remains the anticoagulant of choice for patients with prosthetic heart valves and significant mitral stenosis. There are currently no head-to-head studies that directly compare the different NOACs with one another, but it is expected that there will be more trials in the future that will explore this comparison. Dabigatran is the only NOAC with an FDA approved reversal agent. However, a reversal agent for apixaban is being developed and was successful in recent clinical trials. This review summarizes the clinical trial data on apixaban for atrial fibrillation, compares apixaban to other NOACs and discusses apixaban use in clinical practice.

Unusual Sign from an Unusual Cause: Wellens’ Syndrome due to Myocardial Bridging

It is vital to recognize correctly, chest pain of cardiac etiology. Most commonly, it is because of blood supply-demand inequity in the myocardium. However, the phenomenon of myocardial bridging as a cause of cardiac chest pain has come to attention reasonably recently. Herein, a coronary artery with a normal epicardial orientation develops a transient myocardial course. If the cardiac muscle burden is substantial, the respective artery gets compressed during each cycle of systole, thereby impeding blood flow in the artery. Hence, myocardial bridging has been attributed to as a rare cause of angina. In this case report, the authors discuss a patient in whom myocardial bridging turned out to be an elusive cause of angina. We wish to underscore the importance of being clinically mindful of myocardial bridging when assessing a patient with angina.

Duration of Dual Antiplatelet Therapy Following Drug-Eluting Stent Implantation in Diabetic and Non-Diabetic Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND Diabetic patients account for an increasing number of patients undergoing percutaneous coronary intervention (PCI). However, diabetes mellitus (DM) is associated with increased residual platelet activity during dual antiplatelet treatment (DAPT) and DM patients have worse clinical outcomes after PCI as compared to non-DM. OBJECTIVE To evaluate efficacy and safety of short duration DAPT (S-DAPT) and long duration DAPT (L-DAPT) after drug eluting stent (DES) implantation in DM and non-DM patients. METHODS We searched Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) to identify randomized controlled trials (RCTs) assessing the effect of S-DAPT versus L-DAPT after DES implantation in DM and non-DM patients. Efficacy endpoints were all-cause mortality, cardiac mortality, myocardial infarction (MI), stent thrombosis (ST), target vessel revascularization (TVR), and composite end point of net adverse clinical events (NACE) (all-cause mortality, cardiac mortality, MI, ST, TVR, stroke, major bleeding). Safety endpoints were major bleeding and stroke. Event rates were compared using a forest plot of relative risk using a random effects model. RESULTS We included eight RCTs that randomized 28,318 patients to S-DAPT versus L-DAPT (8234 DM and 20,084 non-DM). S-DAPT was associated with an increased rate of ST in non-DM patients [3.67 (2.04, 6.59)]. There was no significant difference in the rate of all-cause mortality, cardiac mortality, ST, MI, TVR, major bleeding, stroke and NACE with S-DAPT and L-DAPT in DM patients [1.19 (0.72-1.95); 1.25 (0.69, 2.25); 1.52 (0.70, 3.29); 1.33 (0.88, 2.01); 1.39 (0.89, 2.17); 0.92 (0.19, 4.42); 0.98 (0.29, 3.28); and 0.94 (0.57, 1.54) respectively]. Further, there was no significant difference in the rate of all-cause mortality, cardiac mortality, MI, TVR, major bleeding, stroke and NACE with S-DAPT and L-DAPT in non-DM patients [0.93 (0.58, 1.48); 0.75 (0.42, 1.35); 1.52 (0.81, 2.83); 0.99 (0.71, 1.39); 0.72 (0.28, 1.84); 1.01 (0.40, 2.56); and 1.01 (0.77, 1.32) respectively]. CONCLUSION Compared to L-DAPT, S-DAPT was associated with significant increase in rate of ST in non-DM patients. Duration of DAPT had no significant impact on rates of all-cause mortality, cardiac mortality, MI, ST and TVR among DM patients.

Homan’s sign for deep vein thrombosis: A grain of salt?

Deep venous thrombosis (DVT) is a common medical problem with potentially fatal consequences. Development of thrombi in proximal or distal veins is a characteristic feature of DVT. Such emboli can travel from the lower limbs to the lungs resulting in pulmonary embolism. Symptoms of pulmonary embolism include tachypnea, chest pain and at times sudden death. Therefore it is essential that physicians have a high index of suspicion for the signs of DVT. Though DVT may be clinically silent, few clinical signs have been described to rule it out. Pain or discomfort in calf, development of edema and distension of limb veins preclude development of DVT. Perhaps for the diagnosis of DVT, no sign is more famous than the Homan’s Sign. Elicitation of the Homan’s sign involves forced dorsiflexion of the respective ankle in the suspected limb. However, the sign is not very reliable and often non-invasive diagnostic modalities are necessary to confirm the diagnosis of DVT. Such modalities include ultrasonography and venography of the affected limb. The utility and use of the Homan’s sign has gradually waned down over the course of time. Here we attempt to chronicle the history and the clinical significance of the Homan’s sign. The pathophysiology of the sign has been explained as follows. Passive, abrupt and forced ankle dorsiflexion in concert with superadded knee flexion causes mechanical traction on the posterior tibial vein. This traction stimulates the pain sensitive structures in the lower limb. Differential diagnosis of conditions that demonstrate a positive Homan’s sign include intervertebral disc herniation, ruptured Baker’s cyst, neurogenic claudication, gastrocnemius spasm, and cellulitis. Another interesting phenomenon is seen in women who after chronically wearing high heels start wearing flat shoes. In these women, sometimes due tomechanical traction in the lower limb, a positive Homan’s sign can be demonstrated. [32_TD

Acute Pulmonary Embolism Masquerading as Acute Inferior Myocardial Infarction

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