Subcutaneous Defibrillator
- The implantable cardioverter-defibrillator (ICD) has evolved from devices through epicardial patch electrodes introduced by thoracotomy to transvenous leads advanced to the right ventricle
- Transvenous ICD (T-ICD) reduced the morbidity associated w/thoracotomy implants, however involves potential complications including: hemopericardium, hemothorax, pneumothorax, lead dislodgement, lead malfunction, device-related infection, and venous occlusion
- Subcutaneous ICD (S-ICD) offers the advantage of eliminating the need for intravenous & intracardiac leads. Clinical trials have proven its effectiveness in detecting and treating ventricular fibrillation/tachycardia; however its major disadvantage is its inability to provide bradycardia rate support and anti-tachycardia pacing to terminate ventricular tachycardia
- No study has directly compared the T-ICD & the S-ICD, however clinical data suggests that its use be considered in relatively younger patients (i.e., age <40 years), those at increased risk for bacteremia, patients with indwelling intravascular hardware at risk for endovascular infection, or in patients with compromised venous access
Optimal out of hospital cardiac arrest (OHCA) airway management strategies remain unclear. In the US, 80% of OHCA patients receive prehospital airway management, most commonly endotracheal intubation (ETI). There is growing enthusiasm for use of supra-glottic airways (SGA) by EMS because of ease of insertion, and the thought that use of SGA reduces interruptions in chest compressions. More recently, studies have suggested improved survival without the insertion of any advanced airway device at all.
A recent secondary analysis of OHCA outcomes in the Cardiac Arrest Registry to Enhance Survival (CARES) compared patients receiving endotracheal intubation (ETI) versus supra-glottic airway (SGA), and also patients receiving [ETI or SGA] with those receiving no advanced airway.
Of 10,691 OHCA, 5591 received ETI, 3110 SGA, and 1929 had no advanced airway. Unadjusted neurologically-intact survival was: ETI 5.4%, SGA 5.2%, no advanced airway 18.6%. Compared with SGA, ETI achieved higher sustained ROSC, survival to hospital admission, hospital survival, and hospital discharge with good neurologic outcome. Moreover, compared with [ETI or SGA], patients who received no advanced airway attained higher survival to hospital admission, hospital survival, and hospital discharge with good neurologic outcome.
Conclusion: In CARES, patients receiving no advanced airway exhibited superior outcomes than those receiving ETI or SGA. When an advanced airway was used, ETI was associated with improved outcomes compared to SGA.
Perinatally Infected HIV & Cardiovascular Disease
*Perinatally HIV-infected adolescents are susceptible to aggregate atherosclerotic cardiovascular disease risk, but few studies have quantified risk or developed a scoring system
*A recent study of perinatally HIV-infected adolescents calculated coronary artery and abdominal aorta PDAY (Pathobiological Determinants of Atherosclerosis in Youth) scores using modifiable risk factors: HTN, HLD, smoking, obesity and hyperglycemia
*Significant predictors of a high coronary arteries and abdominal aorta scores include: male sex, Hx AIDS-defining condition, long duration of ritonavir-boosted protease inhibitor, and no prior use of tenofovir
*PDAY scores may be useful in identifying high-risk youth who may benefit from early lifestyle or clinical interventions given their trend of increased aggregate atherosclerotic cardiovascular disease risk factor burden
The number of patients with left ventricular assist devices (LVADs) is increasing and development of optimal resuscitative strategies is becoming increasingly important. Despite a lack of evidence, many device manufacturers and hospitals have recommended against performing chest compressions because of fear of cannula dislodgment or damage to the outflow conduit.
A recent retrospective analysis of outcomes in LVAD patients who received chest compressions for cardiac arrest did not support the theory that LVADs would be harmed by conventional resuscitation algorithms.
The study was a limited case series of only 8 LVAD patients over a 4 year period. All patients received compressions and device integrity was subsequently assessed by blood flow data from the LVAD control monitor or by examination on autopsy. Although more research is necessary to determine the utility and effectiveness of compressions in this population, none of the patients in this study had cannula dislodgment and half of the patients had return of neurologic function.
The HEART Score
Acute coronary syndrome defines a spectrum of diseases (unstable angina, NSTEMI, STEMI), without clear ECG abnormalities the diagnosis and disposition can be challenging
Several scoring systems have attempted to risk stratify patients: TIMI, PURSUIT, and GRACE
The TIMI & PURSUIT scores were designed to identify higher-risk patients and long-term mortality
A pilot/observational study has utilized a novel scoring system to risk stratify low to intermediate risk patients
The HEART (History, ECG, Age, Risk factors and Troponin) score:
This scoring system is limited given the small study size and requires further study/validation, but may be an easy, quick, and reliable predictor of outcome in chest pain patients
Early diagnosis and surgical consultation for dissection of the ascending aorta can be life saving. Emergency physicians are increasingly using focused cardiac ultrasound to assess chest pain patients in the ED.
The suprasternal notch view (SSNV), may provide additional information in the assessment of thoracic aortic pathology. A recently performed pilot study aimed to determine the accuracy of using the SSNV, in addition to the more traditional parasternal long axis view in assessing aortic dimensions as well as pathology compared to CTA of the chest.
Using a maximal normal thoracic aortic diameter of 40 mm, diagnostic accuracy in detecting dilation of the aorta was 100%. The study showed that the SSNV is feasible and demonstrates high agreement with measurements made on CTA of the chest.
Pulseless Electrical Activity (PEA)
ACLS algorithm for PEA focuses on memorizing the “ H's & T's" without a systematic approach on how to evaluate & treat the possible etiologies
A modified approach to PEA focuses on “cause-specific” interventions utilizing two simple tools: ECG and Bedside Ultrasound (US)
Simplified PEA Algorithm
♦1st obtain the ECG and assess the QRS-complex length (narrow vs. wide)
♦ A narrow QRS-complex suggests a mechanical problem: RV inflow or outflow obstruction
Utilize bedside US to assess for RV collapsibility vs. dilation
A collapsed RV suggests tamponade, tension PTX or mechanical hyperinflation
A dilated RV suggests PE
The above listed etiologies all have a preserved/hyperdynamic LV Tx begins w/aggressive IVF’s followed by “cause-specific” therapy: pericardiocentesis, needle decompression, forced expiration/vent management, and thrombolysis respectively
♦ A wide QRS-complex suggests a metabolic (hyperK/acidosis/toxins), ischemic, or LV problem
Utilize bedside US to assess for LV hypokinesis/akinesis
For metabolic/toxic etiologies treat w/calcium chloride and sodium bicarbonate +/- vasopressors
For ischemia and LV failure treat w/cardiac cath. vs. thrombolysis +/- vasopressors/inotropes
♦Trauma and several other etiologies of PEA that are seldom forgotten in any critically ill patient (hypothermia, hypoxia, and hypoglycemia) are not included in this algorithm.
Early Atherosclerosis Detection
50 middle-aged asymptomatic subjects free of vascular disease underwent carotid ultrasound (CUS) for risk stratification were also invited to undergo coronary computed tomography angiography (CCTA) or coronary artery calcium score (CAC) to identify which of the 3 imaging modalities was best at identification of early atherosclerosis
Atherosclerosis was observed in 28%, 78%, and 90% of subjects using CAC, CCTA, and CUS, respectively
36 patients with a CAC score = 0, 69% and 86% had atherosclerosis on CCTA and CUS, respectively
Concordance between modalities was highly variable
CUS and CCTA detection of plaque were significantly more sensitive than CAC
Considering the prevalence of subclinical disease on CUS and CCTA, the threshold at which to treat warrants further research
The importance of new ST-segment depressions (STD) and/or T wave inversions (TWI) in lead aVL have not been emphasized or well recognized across specialties. Computer-assisted ECG readings typically report these findings as normal or nonspecific.
There is growing evidence that changes in lead aVL are abnormal, and that paying attention to that lead can be clinically useful. Reciprocal changes presenting as STD or TWI in lead aVL may be indicative of a significant coronary artery lesion and can sometimes be the only ECG manifestation of acute MI.
STD in lead aVL is considered a sensitive marker for early inferior STEMI, and has been shown to help differentiate STEMI from pericarditis. Another recent retrospective study suggests that TWI in aVL might be associated with significant LAD lesions.
Bottom Line: Paying close attention to subtle changes and abnormalities in lead aVL may help in early identification and initiation of therapy for patients who are having an acute MI.
Myocardial Infarction in Women After Childbirth
World Health Organization reports that obesity is the 5th leading cause of global death with the highest impact on women <65 years of age
The association of obesity and cardiovascular risk in young women is currently being researched
A recent nationwide cohort looking at obesity and future cardiovascular risk looked at Danish women giving birth (2004-2009) and followed them a median time of 4.5 years
This study grouped women via pre-pregnancy body mass index (BMI)
1. Underweight (BMI <18.5)
2. Normal weight (BMI <25)
3. Overweight (BMI <30)
4. Obese (BMI >30)
Data revealed that healthy women of fertile age, pre-pregnancy obesity alone was associated with increased risk of myocardial infarction in the years after childbirth
A 48 year old woman has acute chest pain and palpitations over the past several hours. She has felt similar palpitations in the past but never sought medical attention. She arrives to your ED alert and anxious. HR = 270, BP=130/100. ECG is below. What’s the diagnosis and treatment?
Pacing Atrioventricular Block
- Atrioventricular (AV) block is classically treated with restoration of heart rate via right ventricular pacing, however high rates of right ventricular pacing is associated w/ left ventricular systolic dysfunction
- A recent multi-center randomized control trial (RCT) assessed the efficacy of right vs biventricular pacing in heart failure w/ AV block [BLOCK HF Trial]
- Primary outcomes of: morbidity, mortality, and adverse left ventricular remodeling were shown to be significantly lower in biventricular vs right ventricular pacing
- In patients with a high rate of pacing and/or an abnormally low left ventricular ejection fraction biventricular pacing may be more advantageous than conventional right ventricular pacing
Differentiation between right and left ventricular origin of premature beats can be useful clinically.
PVCs arising from the right ventricle have a left bundle branch block morphology (dominant S wave in V1)
PVCs arising from the left ventricle have a right bundle branch block morphology (dominant R wave in V1)
Left Ventricular premature beats are more often associated with heart disease and may precipitate ventricular fibrillation, whereas right ventricular premature beats are commonly seen in individuals with normal hearts.
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Assessment of Intermediate Coronary Lesions
- Coronary angiography alone to assess CAD is fraught with subjectivity
- Fractional flow reserve (FFR) has become the standard to assess/quantify obstructive CAD; it determines the myocardial flow in the presence of stenosis identifying the lesion responsible for ischemia
- FFR assesses focal stenosis, but does not consider diffuse atherosclerotic narrowing or microcirculatory dysfunction as contributors of ischemic heart disease
- An index of microcirculatory resistance (IMR) can be concomitantly measured with FFR during cardiac catheterization to specifically evaluate the microvasculature
- Coronary flow reserve (CFR) was the 1st proposed method for assessment of intermediate coronary lesion, but proved suboptimal because of its variability especially in patients with microvascular dysfunction (diabetes, prior MI, etc.)
- Utilization of FFR, IMR, and CFR together support the existence of differentiated patterns of ischemic heart disease & may help to determine future ischemic events
There is debate and confusion regarding where and how to measure ST elevation (STE). Do you measure the STE at the J-point? Or at 40 msec after the J-point? And how much STE is considered significant? The current guidelines have clarified this issue.
- STE should be measured at the J-point.
- STEMI is defined by STE ≥ 1 mm in at least 2 contiguous leads, with the exception of leads V2-V3.
- STEMI is defined by STE ≥ 2 mm in leads V2-V3 in men.
- STEMI is defined by STE ≥ 1.5 mm in leads V2-V3 in women.
For more cardiology pearls from the 2013 literature , check out Amal Mattu's Articles You've Gotta Know!
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Metoprolol Usage Cardioprotective
Bottom-line: The HEART score can help to objectively risk stratify ED patients with chest pain into low, intermediate, and high risk groups. Using the HEART score can also facilitate more efficient and effective communication with colleagues.
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International_Journal_of_Cardiology_2013_Backus.pdf (371 Kb)
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ECG Following Cardiac Transplant
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