Tag Archives: Cardiology

Rebuilding heart muscle: The hypoxic bubble

Check out the recent Nature publication by Dr. Hesham Sadek‘s group in which they identify and characterize cycling cardiomyocytes in a novel transgenic mouse model. Their work was recently highlighted on KERA and highlights the role of hypoxia signalling and HIF1-alpha in maintaining cardiomyocyte proliferative capacity. This research suggests that adult mammals are capable of cardiac regeneration following ischemic injury and is an important step toward the ultimate goal: cellular therapies for human coronary ischemia!

Figure reprinted with permission by Nature Publishing Group

#GetFit: Cardiorespiratory Fitness and Long-Term Survival in “Low-Risk” Adults

You are young and healthy, meaning that you must be “low-risk,” right? But what does this mean in terms of long-term survival?

In a 2012 study in the Journal of the American Heart Association, a group of authors, including our own Jarret Barry, sought to answer this question. They sought to establish whether cardiorespiratory fitness had important implications for long-term cardiovascular risk among individuals classified as low risk by the Framingham Risk Score (10-year coronary heart disease risk <10%).

The study population was composed of men and women, 30 to 50 years of age in our own city of Dallas, Texas. Eligible individuals were defined as being at low risk for coronary heart disease by Framingham Risk Score at the time of study entry and had no history of diabetes (n=11 190). Cardiorespiratory fitness was determined by maximum graded exercise treadmill tests. Over an average 27±2-year period, 15% of low-fit (quintile 1) compared to 6% of high-fit (quintile 5) individuals died (P<0.001).

The study noted that a 1–metabolic equivalent level increase in baseline fitness was associated with an 11% reduction in all-cause deaths and an 18% reduction in deaths due to cardiovascular disease (CVD) after adjustment for age, sex, body mass index, systolic blood pressure, total cholesterol, blood glucose levels, smoking, and early family history of coronary disease. There was an incremental decrease in CVD risk with increasing fitness quintile, such that the high fit had the lowest adjusted 30-year CVD mortality rate compared to the low fit.

Cardiorespiratory fitness is associated with a significant reduction in long-term CVD among individuals identified as low risk by Framingham Risk Score. These data suggest that preventive lifestyle interventions geared to optimize cardiorespiratory fitness, even among a “low-risk” subset, should be considered to improve CVD-free survival.

See you on the Katy Trail!

Continue reading #GetFit: Cardiorespiratory Fitness and Long-Term Survival in “Low-Risk” Adults

PCSK9 Inhibitors…Closer to Approval?

This week the FDA Endocrinologic and Metabolic Drugs Advisory Committee will discuss the safety and efficacy of two PCSK9 inhibitor drugs (Praluent and Repatha) and may recommend approval of these drugs to lower cholesterol. Recently published research in NEJM showed reduced cardiovascular outcomes with these inhibitors and has sparked guarded optimism from the medical community. UT Southwestern cardiologist, Dr. Amit Khera, was recently quoted in Medscape regarding these powerful cholesterol lowering medications, “If you’re a cardiologist, you must not have a pulse if you’re not excited.” Click on the link below to read more from The Washington Post!

Could these New Cholesterol Drugs Save Many Americans from Heart Attacks?


The FDA panel today recommended approval of the cholesterol drug, alirocumab, in a 13-3 vote. Click on the link below to read a summary from today’s developments from The New York Times.

Federal Panel Recommends Approving New Cholesterol Drug

Get Fit Week! Ideal Cardiovascular Fitness

Get Fit Week

As our year comes to a close, we would like to present our last themed series of posts, a part of GET FIT WEEK. These posts will focus on the scientific evidence and guidelines for obtaining and mantaining physical fitness, with a focus on health benefits and tools for achieving these goals.

Ideal Cardiovascular Fitness

It makes sense to start with ideal cardiovascular fitness! The American Heart Association 2020 Strategic Goals include this idea. It is defined as optimal levels of three cardiovascular risk factors (blood pressure, fasting glucose, cholersterol) and 4 lifestyle behaviors (BMI, smoking, physical activity, and diet). In a cohort study of ~5800 young adults (age range of 29 to 39 years) from the United States, Finland, and Australia, investigators compared the presence of these 7 measures of ideal cardiovascular fitness with carotid intima-media thickness. The ideal numbers for each metric is as follows: BP 120/80, total cholesterol < 5.17 mmol/L, fasting glucose < 5.6 mmol/L, BMI < 25 kg/m2, and no history of smoking (or quit > 1 year ago). Ideal physical activity was defined as >150 min/week of moderate exertion or > 75 min/week of vigorous exertion. The concept of the ideal diet was most complicated, requiring 4 of the following 5 components: > 4.5 cups of fruits or vegetables per day, > two 3.5 oz servings of fish per week, > three 1 oz servings of whole grains per day, < 1500 mg sodium per day, and < 450 kcal from sugary drinks per week. One of the most notable aspects of this study was that only 1% of the participants had all 7 ideal CV health metrics! The findings of the study indicated that, with the presence of each additional “ideal” measure (i.e. well-controlled BP, recommended levels of physical activity, etc.), carotid intima-media thickness was significantly lower. Essentially, this suggests that physical fitness, as defined by the above measures of blood pressure, cholesterol, BMI, smoking, etc., not only makes you feel great, (and need less medications!), it appears to have a significant impact on the burden of atherosclerotic disease. The authors note that “this finding and the fact that complete ideal CV health was very rare among this large sample of young adults strengthen the need for early evaluation of CV risk factors and for development of effective intervention strategies for behavioral change.” The next question is, does this translate into a mortality benefit. To read the full study, click here.

Continue reading Get Fit Week! Ideal Cardiovascular Fitness

Myocardial Infarction Complicated by Heart Block

  • Acute coronary syndrome (ACS) involves rupture or erosion of a coronary plaque with exposure of the subendothelial matrix to circulating blood and subsequent platelet adhesion, platelet activation, and platelet aggregation
  • A thrombus forms, resulting in partial or complete occlusion of the lumen of the coronary artery
  • The initial ECG is nondiagnostic in up to 50% of patients presenting with chest pain, but remains a critical part of the evaluation
  • Complete heart block (CHB) may be associated with an anterior or inferior wall MI
  • High degree AV block is associated with an increase in mortality in patients with an inferior or anterior myocardial infarction
  • Complete heart block with inferior MI generally results from an intranodal lesion and isassociated with a narrow QRS complex and develops in a progressive fashion from 1st to 2nd to 3rd degree block
  • Patients with inferior MI and CHB may be resistant to atropine and its use during active ischemia may cause ventricular fibrillation!
  • Temporary transvenous pacing is recommended
  • Patients with inferior MI and CHB typically don’t need permanent pacing as the rhythm is transient and resolves within 5-7 days

Click on the link below to see an ECG of inferior MI with complete heart block!

ECG (courtesy of Life in the Fast Lane)

A Practical Guide to the Novel Anticoagulants

This morning, Dr. Craig Malloy, Richard A. Lange, M.D. Chair in Cardiology, gave an amazing update for internists on New Therapies fo Atrial Fibrillation. One of the most important topics covered was the noval anticoagulants, or NOACS. Here is a quick review for use in the clinic or hospital!

Dabigatran, rivaroxaban and apixaban are three new drugs that have different mechanisms of action, daily doses, and metabolic and elimination profiles.

Dabigatran (Pradaxa) is a direct thrombin inhibitor (it inhibits factor II) that has a half-life of about 12-14 hours and needs to be administered twice daily. It partially binds plasma proteins and can therefore be partially dialysed. Pradaxa is only eliminated renally: it is therefore contraindicated in patients whose creatinine clearance is

Rivaroxaban (Xarelto) is a direct factor X inhibitor with a half-life of 5-13 hours, but completely binds plasma proteins. It is administered once daily with evening meal in NVAF patients, and twice daily in those with DVT or PE. It is eliminated by the kidney and liver, and can be used at a lower dose if creatinine clearance is15 mL/min in NVAF patients; its use should be avoided in DVT/PE patients whose creatinine clearance is

Apixaban (Eliquis) is a direct factor X inhibitor with a half-life of 9-14 hours, but completely binds plasma proteins. It is administered twice daily and eliminated by kidney and liver. It should not be used if creatinine clearance is

NOAC trial comparisons

Turiel M, Galaverna S, Colombo C, Gianturco L, Stella D (2015) Practical Guide to the New Oral Anticoagulants. J Gen Pract 3:194. doi: 10.4172/2329-9126.1000I194

Internal Medicine Journal Watch – April 2015

STRAIGHT FROM THE HOUSESTAFF – the April 2015 UT Southwestern Internal Medicine Journal Watch! They have summarized important issues in clinical practice, from alcoholic hepatitis to which medications to use for stroke prevention in afib. Make sure to take the EKG challenge at the end! You will have to view this post on our website to access the PDF.  There is a quick run down of the topics below:


  • Corticosteroids in severe alcoholic hepatitis after recent upper GI bleed. Dr. Jan Petrasek reviewing Rudler et al., J Hepatol. 2015 Apr;62(4):816-21. 10.1016/j.jhep.2014.11.003. Epub 2014 Nov 11.
  • Serum ammonia level for the evaluation of hepatic encephalopathy. Dr. Jan Petrasek reviewing Ge et al., JAMA. 2014 Aug 13;312(6):643-4.


  • Extended report: Prediction of cardiovascular risk in rheumatoid arthritis: performance of original and adapted SCORE algorithms. Dr. Brian Skaug reviewing Arts, et al. Ann Rheum Dis. 2015 Feb 17. pii: annrheumdis-2014-206879. doi: 10.1136/annrheumdis-2014-206879

Pulmonary/Critical Care

  • Trial of Early, Goal-Directed Resuscitation for Septic Shock [The Protocolised Management in Sepsis (ProMISe) Trial]. Dr. James Galloway reviewing Mouncey PR et al. N Engl J Med. 2015;372(14):1301-11.
  • A Randomized Trial of Icatibant in ACE-Inhibitor-Induced Angioedema. Dr. James Galloway reviewing Bas M, et al. N Engl J Med. 2015;372(5):418-25.


  • High-Sensitivity Troponin T and N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) and Risk of Incident Heart Failure in Patients with CKD: The Chronic Renal Insufficiency Cohort (CRIC) Study. Dr. Natalia Rocha reviewing Bansal N, et al. JASN 2015; 26:946-956
  • Preoperative renin–angiotensin system inhibitors use linked to reduced acute kidney injury: a systematic review and meta-analysis. Dr. Natalia Rocha reviewing Cheungpasitporn W, et al. Nephrol. Dial. Transplant. 2015; doi: 10.1093/ndt/gfv023


  • Which drug should we use for stroke prevention in atrial fibrillation? Dr. Douglas Darden reviewing Lau, Yee C.; Lip, Gregory Y.H. Current Opinion in Cardiology. 2014 July 29 (4): 293-300.
  • EKG CHALLENGE: Contributed by Dr. Jeanney Lew

Screen Shot 2015-04-29 at 10.49.07 PM

All of the work above comes from the IMJW Editorial Board: Jan Petrasek, Brian Skaug, Ben Galloway, Natalia Rocha, Doug Darden, and Jeanney Lew!

Digoxin Toxicity – A Practical Review


  • Acute digoxin toxicity
    • Time course: initial toxic effects of nausea and vomiting occur at 2-4 hours, peak serum levels at 6 hours and life-threatening cardiovascular complications  at 8-12h
    • GI: anorexia, nausea, vomiting, diarrhoea, abdominal pain
    • Metabolic: hyperkalaemia (early sign of significant toxicity)
    • CVS: enhanced automaticity (atrial tachycardias (e.g. flutter, AF) with AV block, VF, VT, ventricular ectopic beats), bradyarrhythmias (Conduction delays / blocks, slow or regularised AF), hypotension, shock
    • CNS: lethargy, confusion
  • Chronic digoxin toxicity
    • Typically occurs  in the context of intercurrent illness, especially with impaired renal function
    • Clinical features are a combination of toxicity and the intercurrent illness
    • Symptoms may have an insidious onset over days to weeks
    • Features include those of acute digoxin toxicity as well as visual disturbances (e.g. reduced acuity, yellow halos (xanthopsia) and altered color perception (chromatopsia))


  • Urgent K level, creatinine
  • Serum digoxin level –  a steady state level 6 or more hours after the last dose; levels can be misleading as levels near the therapeutic range (0.6-1.3 nmol/L) correlate poorly with severity of intoxication
  • ECG


    • Digoxin-induced cardiotoxicity is refractory to standard measures
      • Bradyarrhythmias
        • Digibind is the definitive treatment
        • Atropine
        • Epinephrine (but may aggravate cardiac irritability)
        • Pacing (rarely effective)
      • Tachyarrhythmias
        • Digibind is the definitive treatment
        • MgSO4as an adjunctive measure
        • Often refractory to cardioversion
    • Hyperkalemia: Insulin and glucose, bicarbonate Calciumis traditionally contra-indicated due to the risk of precipitating a ‘stone heart’.
    • Activated charcoal if the patient presents <1h post-ingestion and not vomiting (unlikely to prevent severe toxicity in large ingestions)
    • Resuscitation as for acute digoxin toxicity
    • Renal replacement therapy may be indicated in the context of renal failure and hyperkalemia
    • Digibind!