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Surgical Steps In Pulmonary Thromboendarterectomy (PTE)

Patients with chronic thromboembolic pulmonary hypertension (CTEPH) present challenges from a surgical and anesthetic standpoint. They often have significant pulmonary collateral vessels to bypass obstructed pulmonary vessels. This, in turn, can increase bronchial vessel flow which can congest the pulmonary vessels even during bicaval venous cannulation. Additionally, large thromboembolic loads create large areas of dead space leading to V/Q mismatch with potential issues like hypoxemia and hypercarbia. This, in turn, can stress the right side of the heart leading to right ventricular pressure/volume overload, functional tricuspid regurgitation, elevated venous pressures, etc.

Pulmonary thromboendarterectomy

Pulmonary thromboendarterectomy (PTE) is the “gold standard” treatment for these patients. My anesthetic plan for PTE includes: general endotracheal anesthesia, arterial line (sometimes bilateral radial lines if anterograde cerebral perfusion is planned), central venous catheter with a PA catheter, inhaled pulmonary vasodilators (Veletri/Flolan) and intraoperative transesophageal echocardiography (TEE). In particular with TEE, I’m looking for signs of right ventricular failure, clots, an underfilled left ventricle, etc.

After a median sternotomy and systemic heparinization, the ascending aorta (arterial) and the SVC/IVC (bicaval venous) are cannulated in preparation for cardiopulmonary bypass (CPB). An aortic root vent is placed and CPB is initiated. At this point, a left atrial vent is placed via the right superior pulmonary vein (RSPV) and cooling for deep hypothermic circulatory arrest (DHCA) is initiated. The right pulmonary artery (RPA) is opened with an endarterectomy carried to the segmental branches. A mirror procedure is performed on the left pulmonary artery (LPA).

Once we reach ~ 18-20°C, circulatory arrest begins and the remainder of the RPA endarterectomy is completed. Perfusion is resumed while closing the RPA. A mirror procedure is again carried on the LPA. DHCA allows the surgeon to have a bloodless field to optimize their endarterectomy. After rewarming, protamine administration, and CPB decannulation, hemostasis is achieved and the chest is closed in anatomic layers.

Drop me a comment with questions! 🙂

Surgical Steps In Pulmonary Thromboendarterectomy (PTE)
Rishi

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Transcaval Transcatheter Aortic Valve Replacement (TAVR)

For patients with difficult arterial access (namely calcified/narrowed femoral and subclavian arteries), a transcaval approach offers another alternative. In this technique, interventional cardiologists guide a catheter through the femoral vein into the abdominal inferior vena cava (IVC). Using prior CT imaging and intraprocedural fluoroscopy, they electrify a venous guidewire from the IVC into the aorta where it’s essentially “caught” by a snare and advanced retrograde into the aortic root to perform the TAVR in the conventional manner.

Hybrid structural heart lab

Yes, there’s a hole between the IVC and abdominal aorta in the retroperitoneal space bridged by the TAVR delivery catheter. After the procedure is finished, the aorta is typically closed with an Amplatzer device while the hole in the inferior vena cava is left open. The thought is that the pressure within the retroperitoneal space (~20 mmHg) exceeds that of the venous pressure in the IVC (~10 mmHg). This pressure gradient suggests that blood should remain intravascular.

As an anesthesiologist, I still attempt my routine TAVR anesthestic; however, in addition to the considerations associated with TAVR (heart block, hypotension, loss of pacing, aortic root disruption, coronary artery occlusion, peripheral vascular injury, etc.), I must always consider the potential for retroperitoneal hemorrhage. You can hide a lot of volume in this space, and since our patients are supine for the procedure, physical signs such as bruising may not be apparent. Any form of hemodynamic lability refractory to conventional interventions should entertain the need for a stat CT or venogram to look for extravasation.

Transcaval Transcatheter Aortic Valve Replacement (TAVR)
Rishi

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The Denervated Heart

The concept of a denervated heart is a significant consideration in patients receiving orthotopic heart transplants. When these donor hearts are procured, there’s no way to preserve native autonomic regulation (ie, vagal input). After transplantation, it can take many months/years before some semblance of autonomic regulation is reestablished. We can also see a similar pattern in patients with autonomic neuropathy due to end-stage diabetes.

Donor heart

When we wean off cardiopulmonary bypass after a heart transplant, it’s important to start some sort of direct acting adrenergic agent like dobutamine or epinephrine coupled with epicardial pacing to maintain an adequate cardiac output. Of note, the Frank-Starling law is an instrinsic property of the myocardium independent of autonomic input. Optimizing preload for these patients to carefully balance acute right heart overloading with sufficient forward flow is often times difficult. I use TEE, bedside TTE, and monitors like PA catheters to help determine the appropriate interventions at the right time: diuresis, increasing inotropy, weaning vasopressors, administering volume, vasodilation, etc.

Drop me a comment below with questions!

The Denervated Heart
Rishi

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Surgical Steps In CentriMag Biventricular Assist Device (BiVAD) Placement

CentriMag devices are implanted for acute right and/or left-sided circulatory support but often times used for extended periods of time for patients with acute heart failure awaiting a heart transplant. With CentriMag devices, patients can ambulate and stay conditioned in preparation for their orthotopic heart transplant. These devices rely on MagLev technology whereby a free-floating rotor suspended within a constantly adjusted magnetic field delivers blood flow in an environment with minimal shear forces and stasis to reduce cell trauma and clots, respectively.

My anesthetic plan for CentriMag placement includes: general endotracheal anesthesia, arterial line, central venous catheter (often times with PA catheter) and intraoperative transesophageal echocardiography (TEE). So how are these devices placed for right and left ventricular support?

After a median sternotomy and systemic heparinization, a graft is sewn onto the ascending aorta with an aortic cannula placed within the graft prior to venous cannulation of the right atrium. Cardiopulmonary bypass (CPB) is initiated. The LVAD CentriMag drains blood from the left ventricular (LV) apex and returns it to the aortic graft. The RVAD CentriMag drains blood from the right atrium via a large venous cannula and returns it into the pulmonary artery (PA) via the right ventricle (RV). CPB is weaned, protamine is administered to reverse systemic heparinization, hemostasis is achieved, and the incision is closed in anatomic layers with sutures and stainless steel wires for the sternum.

In the post-operative x-ray above, you can see the CentriMag BiVAD cannulas with other things to note: right internal jugular introducer with PA catheter, pacemaker/ICD leads, endotracheal tube, orogastric tube, sternotomy wires, two mediastinal chest tubes, one left pleural chest tube, one right pleural chest tube.

Drop me a comment below with questions! 🙂

Surgical Steps In CentriMag Biventricular Assist Device (BiVAD) Placement
Rishi

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Surgical Steps In HeartMate 3 LVAD Placement

Left ventricular assist devices (LVADs) like the HeartMate 3 are routinely being implanted as a mechanical circulatory bridge-to-transplant (BTT) or destination therapy (DT). My anesthetic plan for LVAD placement includes: general endotracheal anesthesia, arterial line, central venous catheter (often times with PA catheter) and intraoperative transesophageal echocardiography (TEE). In particular with TEE, I’m looking for aortic insufficiency, clots, and intracardiac shunts like ASDs/PFOs (this is where a bubble study comes in handy!)

The operation starts off with a median sternotomy followed by arterial cannulation (ascending aorta) and venous cannulation (bicaval). After initiating cardiopulmonary bypass (CPB), the LVAD’s inflow cannula is sewn onto the left ventricle (LV) and the outflow cannula is sewn onto the ascending aorta in an end-to-side fashion. An outflow graft clip is placed with subsequent deairing of the LVAD system. CPB is weaned, protamine is administered to reverse systemic heparinization, hemostasis is achieved, and the incision is closed in anatomic layers with sutures and stainless steel wires for the sternum.

  • HeartMate 3
  • Post-operative chest x-ray
  • Post-operative chest x-ray

In the x-rays above, you can see the HeartMate 3 LVAD inflow adhered to the left ventricular apex. Other things to note on the x-ray: right internal jugular introducer with PA catheter, pacemaker/ICD leads, endotracheal tube, orogastric tube, sternotomy wires, two mediastinal chest tubes, one left pleural chest tube, one right pleural chest tube.

Drop me a comment below with questions! 🙂

Surgical Steps In HeartMate 3 LVAD Placement
Rishi

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Bubble Study On Transesophageal Echocardiography

A “bubble study” is often utilized to confirm the presence of shunting across the interatrial septum (IAS) via patent foremen ovale (PFO) or atrial septal defects (ASD). This study is used in combination with color flow doppler and simple 2-dimensional inspection of the IAS anatomy to determine if there indeed is a defect.

A Valsalva maneuver increases intrathoracic pressure and compresses the compliant, low-pressure superior and inferior vena cavas. This, in turn, transiently drops blood return to the right atrium creating low right atrial pressure. Once the Valsalva is relieved, blood rushes back into the right atrium generating a higher right atrial pressure than at baseline. This should cause the interatrial septum to bow into the left atrium. Identification and closure of any PFO/ASDs is imperative before surgeries like a left ventricular assist device (LVAD) implantation to prevent right-to-left shunting and hypoxemia.

Here’s a great video showing the process!

Detection of Patent Foramen Ovale Using Contrast Transesophageal Echocardiography - YouTube

Bubble Study On Transesophageal Echocardiography
Rishi

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Directly Link To Social Media User Profile In Swift Application

Here’s how I use UIButtons on EchoTools to link to my social media platforms. If a user has the specific app already installed (ie, Facebook or Instagram), my profile will launch within that app. Otherwise they will be routed to the web version of my profile.

There are plenty of resources showing how to use XCode to add a UIButton in your project. You’ll then need to add an IBAction associated with that UIButton in a Swift file. Replace “yourUSERNAME” with your relevant username for each social media scheme below.

Instagram
    @IBAction func igButtonClick(_ sender: Any)
    {
            let appURL = URL(string: "instagram://user?username=yourUSERNAME")!
            let application = UIApplication.shared
            
            if application.canOpenURL(appURL)
            {
                application.open(appURL)
            }
            else
            {
                let webURL = URL(string: "https://instagram.com/yourUSERNAME")!
                application.open(webURL)
            }
    }
Facebook
    @IBAction func fbButtonClick(_ sender: Any)
    {
        let appURL = URL(string: "fb://profile/yourUSERNAME")!
        let application = UIApplication.shared
        
        if application.canOpenURL(appURL)
        {
            application.open(appURL)
        }
        else
        {
            let webURL = URL(string: "https://www.facebook.com/yourUSERNAME")!
            application.open(webURL)
        }
    }
LinkedIn
    @IBAction func linkedinButtonClick(_ sender: Any)
    {
        let appURL = URL(string: "linkedin://profile/yourUSERNAME/")!
        let application = UIApplication.shared
        
        if application.canOpenURL(appURL)
        {
            application.open(appURL)
        }
        else
        {
            let webURL = URL(string: "https://www.linkedin.com/in/yourUSERNAME/")!
            application.open(webURL)
        }
    }
Twitter
    @IBAction func twitterButtonClicked(_ sender: Any)
    {
        let appURL = URL(string: "twitter://user?screen_name=yourUSERNAME")!
        let application = UIApplication.shared
        
        if application.canOpenURL(appURL)
        {
            application.open(appURL)
        }
        else
        {
            let webURL = URL(string: "https://twitter.com/yourUSERNAME")!
            application.open(webURL)
        }
    }

Let me know if this helps! 🙂

Directly Link To Social Media User Profile In Swift Application
Rishi

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Safely Drawing Up And Labeling Medications

Every day as an anesthesiologist, I reconstitute, draw up, and administer antibiotics, hypnotics, narcotics, paralytics, inotropes/pressors, blood products, fluids, vasodilators, and a myriad of other medications. Each year, the FDA receives over 100,000 reports associated with a suspected medication error causing hospitalization, life-threatening emergency, morbidity, and even death!

In light of the recent headlines regarding the fatal administration of vecuronium instead of midazolam (Versed), I wanted to see how you all promote safe medication administration practices. Here are two things I do with virtually every medication.

First, I pre-label my syringes both sideways and circumferentially. Next, whenever I draw medications out of a vial, I have the inverted medication label facing me and the syringe label. This way, I can ensure I’m filling the right syringe with the right medication at the expected concentration.

  • Syringe and vial label in line while drawing up medication
  • Rocuronium labeled horizontally and circumferentially


Whether it’s cross-checking certain medications with a licensed provider, separating medications which look and sound similar, using electronically generated labels from medication QR codes, or even simple “off-the-protocol” tips, drop me a comment with what you do regarding medication safety and a tag a friend who might be interested in seeing suggestions! We need to do better!

Safely Drawing Up And Labeling Medications
Rishi

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Phenobarbital For Alcohol Withdrawal

At the beginning of my medical training, I grew accustomed to benzodiazepines like lorazepam, chlordiazepoxide, and diazepam being used as the cornerstone of therapy for alcohol withdrawal based on symptoms and the Clinical Institute Withdrawal Assessment of Alcohol (CIWA) protocol. During my ICU fellowship, I transitioned over to using phenobarbital – a barbiturate with sedative and anticonvulsant properties that depresses cortical activities to also achieve hypnosis. Furthermore, the literature (and pharmacology) suggest less paradoxical reactions with barbiturates compared to benzodiazepines. Furthermore, barbiturates stimulate GABA (inhibition) while driving down glutaminergic (excitatory) activity. Win-win! 🙂

In patients with severe alcohol withdrawal histories (ie, withdrawal seizures, delirium tremens, prior ICU admissions for detoxification, benzodiazepine resistance/paradoxical reactions), phenobarbital therapy may be especially advantageous! However, if patients have a history of prior Stevens Johnson syndrome or toxic epidermal necrolysis (SJS/TEN) or acute intermittent porphyria (AIP), I tend to be wary.

So how does this actually work?

First, I try to stratify the risk for respiratory depression based on concomitant benzodiazepines/opioids, pulmonary reserve, age, etc. Then I’ll load phenobarbital over 30 minutes based on ideal body weight: 12-15 mg/kg for low risk, 8-12 mg/kg for medium risk, and 5-8 mg/kg for high risk. If the patient has active symptoms of withdrawal or recent alcohol use, then I’ll usually opt for a higher loading dose.

If active signs of withdrawal persist after the loading infusion (tremor, sweating, delirium, etc.), I’ll consider intravenous administration anywhere from 130 – 260 mg every 30-60 minutes as needed.

Once patients have stabilized and moved to a step-down or general medical-surgical floor bed, they can get oral phenobarbital (100-200 mg every hour) depending on the severity of their symptoms.

An important caveat is that other respiratory depressants should be used with extreme caution! Furthermore, other etiologies of delirium must be considered over the course of hospitalization if patients seem to remain refractory to therapy (ie, stroke, electrolyte abnormalities, polypharmacy, pain, sepsis, etc.)

Drop me a comment below with questions! 🙂

Phenobarbital For Alcohol Withdrawal
Rishi

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Farewell Targus – Enter The NOMATIC Messenger Bag

Its been over a decade since I purchased my Targus CityGear Atlanta messenger bag… a bag that has held a myriad of smartphones, laptops, sunglasses, interview suits (yes, for real), wallets, watches, chargers, folders, papers… and the list goes on and on. It traveled with me on every interview. I used it as a pre-med in college, as a medical student, as a resident, and throughout fellowship. Its been at my side throughout thick and thin. And now I’m making it sound like a spouse, lol.

Unfortunately, this bag finally starting getting tattered and torn to a point where I wanted to upgrade. Two weeks ago, I received my NOMATIC messenger bag, and thus far, have been incredibly pleased with its materials and clever compartments! It fits my 13″ MacBook, 11″ iPad Pro, Sony headphones, cables, HydroFlask, work-related gear (badges, scrub cap, pager), sunglasses, and a myriad of other things with incredibly efficiency! Check out the pictures below, and drop me a comment with what you think!

Farewell Targus – Enter The NOMATIC Messenger Bag
Rishi

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