Dr. Usman's Cardiology Notes

  Hemodynamic formulas are fundamental tools in cardiology and critical care, allowing clinicians to quantify cardiac performance, vascular tone, and circulatory efficiency. Understanding these calculations helps in diagnosing shock states, guiding fluid therapy, titrating vasoactive drugs, and interpreting invasive hemodynamic monitoring. Cardiac Output (CO) and Cardiac Index (CI): Cardiac output represents the volume of blood pumped by the heart per minute and is calculated as stroke volume multiplied by heart rate (CO = SV × HR). Normal CO ranges from 4–8 L/min. Because CO varies with body size, cardiac index adjusts CO for body surface area (CI = CO/BSA), providing a more accurate assessment of cardiac performance. A normal CI is 2.2–4.0 L/min/m². Low CI suggests pump failure or hypovolemia, while high CI is seen in sepsis or hyperdynamic states. Stroke Volume (SV) and Stroke Volume Index (SVI): Stroke volume is the amount of blood ejected from the left ventricle with each hear...

Acute Pericarditis – A Complete Clinical Guide for Practice Definition Acute pericarditis is an inflammatory condition of the pericardium lasting less than 4–6 weeks. It is a common cause of acute chest pain and should always be differentiated from acute coronary syndromes. Epidemiology Acute pericarditis accounts for approximately 5% of emergency department visits for chest pain not related to myocardial infarction. It affects all age groups, with a slight male predominance. Etiology In most cases, acute pericarditis is idiopathic, presumed viral. Common causes include: • Viral: Coxsackievirus, echovirus, influenza, COVID-19 • Bacterial: Tuberculosis (important in endemic regions), staphylococci, streptococci • Post–myocardial injury: Early post-MI, Dressler syndrome • Autoimmune: SLE, rheumatoid arthritis • Metabolic: Uremia • Neoplastic: Lung, breast, lymphoma • Drug-induced and radiation-related Clinical Presentation Chest Pain • Sharp, pleuritic chest pain • Worse on inspiration a...

True mitral annular disjunction (MAD) is a genuine structural abnormality in which there is a real separation between the hinge point of the posterior mitral leaflet and the left ventricular myocardium. On echocardiography, especially in parasternal long-axis view during systole, the mitral annulus is seen displaced atrially with a clear gap between the annulus and the ventricular wall. This separation persists consistently, is best appreciated in systole, and is often associated with mitral valve prolapse, excessive annular motion, and sometimes ventricular arrhythmias. Pseudo mitral annular disjunction is an apparent or false impression of annular separation caused by imaging artifacts or altered cardiac geometry rather than a true anatomic defect. It may be seen due to oblique imaging planes, heavy mitral annular calcification, leaflet billowing, translational motion of the heart, or marked left atrial enlargement. In pseudo MAD, the apparent gap disappears with correct probe alignm...

Early Repolarization: Classic vs New Definitions Explained Early repolarization (ER) is a common ECG finding, long considered benign, but modern understanding has refined its definition and clinical relevance. This article explains the classic and newer definitions of early repolarization using ECG morphology, focusing on the J-point, J-wave, ST segment, and terminal QRS changes. Introduction Early repolarization refers to ECG patterns reflecting changes at the end of ventricular depolarization and the beginning of repolarization. Traditionally associated with ST elevation in young, healthy individuals, ER is now defined more precisely based on J-point morphology rather than ST elevation alone. Classic Definition of Early Repolarization The classic definition of early repolarization was centered on ST-segment elevation. Key ECG Features (Classic Definition) 1. J-point elevation The J-point is elevated above the baseline, typically ≥1 mm. 2. Concave upward ST elevation The ST segment sh...

Apixaban Dose Reduction: ABC Rule Explained (Age, Body Weight, Creatinine) Apixaban is a direct oral anticoagulant (DOAC) widely used for stroke prevention in non-valvular atrial fibrillation and for treatment and secondary prevention of venous thromboembolism. While the standard dose is 5 mg twice daily, dose reduction is crucial in selected patients to balance thromboembolic protection against bleeding risk. The ABC mnemonic offers a simple, bedside-friendly way to remember when dose reduction is indicated. Standard Apixaban Dose • 5 mg twice daily Reduced Apixaban Dose • 2.5 mg twice daily Key Rule Reduce the dose to 2.5 mg twice daily if the patient meets any two of the following three criteria (ABC). A – Age Age ≥ 80 years Advanced age is associated with reduced drug clearance, altered pharmacodynamics, and higher bleeding risk. Elderly patients often have frailty, comorbidities, and polypharmacy, all of which increase anticoagulant sensitivity. Clinical relevance • Higher peak pl...

  NOACs (DOACs) Dosing in DVT and Pulmonary Embolism Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is now routinely treated with non–vitamin K antagonist oral anticoagulants (NOACs), also known as DOACs. They are preferred over warfarin in most patients because of predictable pharmacokinetics, fewer interactions, and no need for routine INR monitoring. This post focuses purely on correct dosing, the most common area of confusion in real-world practice. Approved NOACs for DVT and PE Four NOACs are commonly used for treatment of acute DVT and PE. Not all follow the same initiation strategy, which is clinically important. 1. Rivaroxaban 2. Apixaban 3. Dabigatran 4. Edoxaban Rivaroxaban and apixaban can be started immediately as monotherapy. Dabigatran and edoxaban require initial parenteral anticoagulation. Rivaroxaban dosing in DVT and PE Rivaroxaban uses a high-dose lead-in phase followed by standard maintenance dosing. Initial ...

ECG Changes in Potassium Imbalance (Normokalemia, Hypokalemia, Hyperkalemia) Potassium plays a central role in cardiac electrophysiology. Even small deviations from normal serum potassium levels can produce characteristic and sometimes life-threatening ECG changes. Understanding these patterns helps clinicians detect electrolyte disturbances early, often before laboratory confirmation. This post explains ECG findings in normokalemia, hypokalemia, and hyperkalemia in a simple, clinically relevant, and bedside-oriented manner. Normokalemia: The Reference ECG A normal potassium level produces a balanced and stable cardiac electrical pattern. Key ECG features: Normal P wave with normal amplitude and duration Normal PR interval Narrow QRS complex Rounded, normal-sized T wave U wave may be absent or very shallow if present Clinical relevance: This ECG serves as the baseline for comparison. Any deviation from this pattern should raise suspicion of electrolyte or metabolic abnormalities. Hypok...